Rules for Classification and Construction III Naval Ship Technology

1 Surface Ships

2 Propulsion Plants

Edition 2012

The following Rules come into force on 1 May 2012.

Alterations to the preceding Edition are marked by beams at the text margin.

Germanischer Lloyd SE

Head Office Brooktorkai 18, 20457 Hamburg, Germany Phone: +49 40 36149-0 Fax: +49 40 36149-200 [email protected]

www.gl-group.com

"General Terms and Conditions" of the respective latest edition will be applicable (see Rules for Classification and Construction, I - Ship Technology, Part 0 - Classification and Surveys).

Reproduction by printing or photostatic means is only permissible with the consent of Germanischer Lloyd SE.

Published by: Germanischer Lloyd SE, Hamburg III - Part 1 Table of Contents Chapter 2 GL 2012 Page 3

Table of Contents

Section 1 General Rules and Instructions A. General ...... 1- 1 B. Definitions ...... 1- 2 C. Documents for Approval ...... 1- 3 D. Ambient Conditions ...... 1- 4 E. Materials ...... 1- 10 F. Fuels and Consumables for Operation ...... 1- 10 G. Safety Equipment and Protective Measures ...... 1- 11 H. Survivability ...... 1- 12

Section 2 Design and Construction of the Machinery Installation A. General ...... 2- 1 B. Dimensions of Components ...... 2- 1 C. Availability of Machinery ...... 2- 2 D. Control and Regulating ...... 2- 2 E. Propulsion Plant ...... 2- 2 F. Turning Appliances ...... 2- 6 G. Operating and Maintenance Instructions ...... 2- 6 H. Markings, Identification ...... 2- 6 I. Engine Room Equipment ...... 2- 6 J. Communication and Signalling Equipment ...... 2- 7 K. Redundant Systems ...... 2- 7

Section 3 Internal Combustion Engines A. General ...... 3- 1 B. Documents for Approval ...... 3- 2 C. Crankshaft Calculation ...... 3- 4 D. Materials ...... 3- 4 E. Tests and Trials ...... 3- 7 F. Safety Devices ...... 3- 12 G. Auxiliary Systems ...... 3- 16 H. Control Equipment ...... 3- 18 I. Alarms ...... 3- 19 J. Engine Alignment/Seating ...... 3- 19 K. Exhaust Gas Cleaning Systems ...... 3- 19

Section 4a Thermal Turbomachinery/Gas Turbines A. General ...... 4a- 1 B. Materials ...... 4a- 3 C. Design and Construction ...... 4a- 3 D. Control and Monitoring ...... 4a- 6 E. Arrangement and Installation ...... 4a- 9 F. Tests and Trials ...... 4a- 9 Chapter 2 Table of Contents III - Part 1 Page 4 GL 2012

Section 4b Thermal Turbomachinery/ Exhaust Gas Turbochargers A. General ...... 4b- 1 B. Design and Installation ...... 4b- 1 C. Tests ...... 4b- 2 D. Shop Approvals ...... 4b- 4

Section 5 Main Shafting A. General ...... 5- 1 B. Materials ...... 5- 1 C. Shaft Dimensioning ...... 5- 2 D. Design ...... 5- 4 E. Balancing and Testing ...... 5- 9 F. Special Requirements for Fibre Laminate Shafts ...... 5- 9

Section 6 Gears, Couplings A. General ...... 6- 1 B. Materials ...... 6- 1 C. Calculation of the Load-Bearing Capacity of Gear Theeth ...... 6- 1 D. Gear Shafts ...... 6- 6 E. Equipment ...... 6- 7 F. Balancing and Testing ...... 6- 8 G. Design and Construction of Couplings ...... 6- 9

Section 7a Propulsors A. General ...... 7a- 1 B. Materials ...... 7a- 2 C. Design and Dimensioning of Propellers ...... 7a- 3 D. Controllable Pitch Propellers ...... 7a- 7 E. Propeller Mounting ...... 7a- 8 F. Balancing and Testing ...... 7a- 10 G. Lateral Thrust Units ...... 7a- 10 H. Special Forms of Propulsion Systems ...... 7a- 11 I. Dynamic Positioning Systems (DP Systems) ...... 7a- 12 J. Cavitation Noise of Propellers ...... 7a- 14

Section 7b Azimuthing Propulsors A. General ...... 7b- 1 B. Materials ...... 7b- 2 C. Design of Azimuthing Propulsors ...... 7b- 3 D. Design of Steering Device ...... 7b- 5 E. Auxiliary Equipment ...... 7b- 8 F. Hydraulic Systems ...... 7b- 9 G. Electrical Installations ...... 7b- 10 H. Testing and Trials ...... 7b- 12 III - Part 1 Table of Contents Chapter 2 GL 2012 Page 5

Section 8 Torsional Vibrations

A. General ...... 8- 1 B. Calculation of Torsional Vibrations ...... 8- 1 C. Permissible Torsional Vibration Stresses ...... 8- 2 D. Torsional Vibration Measurements ...... 8- 5 E. Prohibited Ranges of Operation ...... 8- 6 F. Auxiliary Machinery ...... 8- 6

Section 9 Machinery for Ships with Ice Classes

A. General ...... 9- 1 B. Requirements for Notation E ...... 9- 1

Section 10 Spare Parts

A. General ...... 10- 1 B. Volume of Spare Parts ...... 10- 1

Section 11 Special Requirements of the Naval Ship Code

A. General ...... 11- 1 B. Performance Requirements of Chapter IV ...... 11- 1

III - Part 1 Index Chapter 2 GL 2012 Page 7

Index

A Accessibility ...... 2-6 diesel engines ...... 3-1 Air blow-out device ...... 7a-1 inlet system ...... 4a-9 Alarm ...... 2-7, 3-19, 4a-8, 7b-10 Alignment ...... 4a-9, 5-8 Ambient conditions ...... 1-4, 3-1 Application factors ...... 6-6 Arrangement of shaft bearings ...... 5-6 Auxiliary ...... 4a-1 engines ...... 3-19, 10-3 machinery ...... 8-6 systems ...... 2-8, 3-16, 7b-8 Availability of machinery ...... 2-2 Azimuthing propulsors ...... 2-9, 7b-1

B Balancing ...... 4a-10, 4b-3, 5-9, 7a-10 gear wheels, pinions, shafts, gear couplings ...... 6-8 Bearing ...... 4a-4, 5-6, 5-7, 7b-3, 7b-7 intermediate ...... 5-7 lubrication ...... 4b-2 Blade sections ...... 7a-6 strength ...... 4a-4 thickness ...... 7a-6 Block diagrams ...... 2-7 Bolts ...... 5-6, 7a-8, 7b-8 Bow thruster ...... 8-6 Bulkheads ...... 2-10

C Calculation ...... 7a-6, 8-1 Cavitation noise of propellers ...... 7a-14 Chapter 2 Index III - Part 1 Page 8 GL 2012

Certification ...... 3-5, 3-20, 4a-3, 7b-12

Characteristic values Cw ...... 7a-3 Charge air ...... 3-18 Clutches ...... 6-10, 6-11, 7b-4 Communication and signalling equipment ...... 2-7 Compartment separation ...... 2-10 Components ...... 2-1, 3-2, 3-10, 7b-2, 7b-7 Compressors, spare parts ...... 10-4 Concept of Operations Statement (ConOps) ...... 11-1 Connection lines ...... 2-9 Consumables ...... 1-10 Control ...... 2-2, 3-18, 4a-6, 7a-7, 7a-12, 7b-6 systems ...... 2-8, 2-9 Controllable pitch propellers ...... 7a-7 Cooling water system ...... 3-18 Corrosion protection ...... 2-2, 7a-2 Couplings ...... 3-4, 5-5, 6-1, 6-9 Crankcase airing ...... 3-14 safety devices ...... 3-14 venting ...... 3-14 Crankshafts ...... 3-4, 8-2 Cycloidal propellers ...... 7a-11

D Definitions ...... 1-2, 4a-1, 4b-1 Diesel engine, spare parts ...... 10-1 Documents for approval ...... 1-3, 2-7, 3-2, 3-3, 3-4, 3-20, 4a-2, 4b-1, 5-1, 6-1, 7a-1, 7a-10, 7a-13, 7b-1 Dynamic load factor ...... 7a-6 Dynamic positioning ...... 7a-12

E Earthing ...... 3-12 Electric propeller drive ...... 2-9, 7b-3, 9-3 Emergency exits ...... 2-10 operation ...... 3-8, 4a-6, 4a-12 Enclosure, gasturbines ...... 4a-5 III - Part 1 Index Chapter 2 GL 2012 Page 9

Engine alignment ...... 3-19 telegraph ...... 2-7 Environmental conditions ...... 1-4 Essential equipment ...... 1-2 Exhaust gas cleaning systems ...... 3-19 outlet system ...... 3-18, 4a-9 turbocharger ...... 4b-1

F Failure Mode and Effect Analysis (FMEA) ...... 2-8, 4a-6, 7a-13 Fibre laminate shafts ...... 5-9 Fire resistance ...... 2-10 Flange connections ...... 7a-9 Flexible couplings ...... 6-9, 8-3 Form factors ...... 8-5 Fuel ...... 1-10, 3-1, 4a-6 lines, return lines, shielding ...... 3-16 systems ...... 2-9

G Gas turbines ...... 4a-1, 10-4 Gears ...... 7b-3, 7b-7, 8-3, 9-3 casings ...... 6-8 couplings ...... 6-1 equipment ...... 6-7 input data ...... 6-5 shafts ...... 6-6 Generator sets ...... 4a-12, 6-1 Generators ...... 3-12, 8-6 Governors ...... 3-13

H Hydraulic ...... 7a-12, 7b-6, 7b-9, 10-5 couplings ...... 6-11

I Ice class ...... 9-1 reinforcement factor ...... 9-3 Chapter 2 Index III - Part 1 Page 10 GL 2012

strengthening factor ...... 9-1 Inclinations and movements of the ship ...... 1-4 Indicators actual setting of blades, c.p. propellers ...... 7a-8 azimuthing propulsors ...... 7b-10 internal combustion engines ...... 3-20 Inspection covers ...... 6-8 Interconnection feeder ...... 2-9 Internal combustion engines ...... 3-1

L Lateral thrust units ...... 7a-10 Lighting ...... 2-7 Load-bearing capacity ...... 6-1 Lubrication ...... 2-8, 3-17, 4a-5, 6-7, 7b-3

M Machinery control centre ...... 2-7 installation ...... 2-1 Maintenance ...... 4a-4, 7b-2 instructions ...... 2-6 Manoeuvrability ...... 2-8 Manoeuvring ...... 2-3, 7a-12, 11-2 qualities ...... 2-8 Manufacturing under license agreement ...... 3-2, 4b-4 Markings ...... 2-6 Materials ...... 1-10, 2-1, 3-4, 3-21, 4a-3, 4b-2, 5-1, 6-1, 7a-2, 7a-9, 7a-10, 7b-2 Minimum speed ...... 2-8 Model tests ...... 2-8 Monitoring equipment ...... 2-6, 4a-6 Multi-engine systems ...... 2-3 Multiple-shaft systems ...... 2-3

N Naval Ship Code (NSC) ...... 1-1, 11-1 NBC protection ...... 4a-5 Noise ...... 2-7, 7a-1 III - Part 1 Index Chapter 2 GL 2012 Page 11

O Oil mist detection ...... 3-15 One failure principle ...... 1-2 Operating ...... 2-6 conditions ...... 1-4 instructions ...... 2-6 Operational information ...... 11-1

P Partition ...... 2-10 bulkhead ...... 2-9 Percentage area of contact - gear teeth ...... 6-9 Pitch control mechanism ...... 7a-8 Podded drives ...... 7b-1, 7b-4, 7b-6, 7b-11 Polar class ...... 9-1 Power diagram ...... 3-1, 3-9 Preheating ...... 2-9 Pressure control ...... 6-7 gauges ...... 2-6 tests ...... 3-7, 7b-12 Prohibited ranges of operation ...... 8-6 Propellers ...... 7a-3, 7b-3 ice class ...... 9-2 mounting ...... 7a-8, 9-2 partially submerged ...... 7a-11 shaft protection ...... 5-5 shafts ...... 9-1 singing ...... 7a-1 Propulsion ...... 2-2, 4a-12, 7a-1, 11-1 Propulsors ...... 7a-1 Protective measures ...... 1-11 Pumps ...... 7a-7, 7a-8, 10-4

Q Quality classes of propellers ...... 7a-10

R Rated power ...... 3-1 Chapter 2 Index III - Part 1 Page 12 GL 2012

Redundant propulsion ...... 2-7 Resistance to seawater ...... 7a-2 Restricted service area ...... 10-1 Rudders ...... 2-9 position indicators ...... 2-9

S Safety devices ...... 3-12, 4a-7 crankcase ...... 3-14 lubricating oil system ...... 3-16 starting air system ...... 3-16 Safety equipment ...... 1-11 Screw connections ...... 2-1 Sea trials ...... 2-2, 2-8, 2-10, 4a-13, 6-8, 7b-14 Seawater supply ...... 2-9 Shaft alignment ...... 4a-9, 5-8 dimensions ...... 5-1, 5-2 earthing ...... 5-9 liners ...... 5-5 locking ...... 5-9, 7b-4 made of pipes ...... 5-3 revolution indicator ...... 2-7 tapers and propeller nut threads ...... 5-4 Shaft-driven generators ...... 8-3 Shafting ...... 5-1, 7b-3, 8-2 Shielding ...... 3-16 Shipboard trials ...... 3-11, 3-21, 7a-11 Shock ...... 5-4 Shop approvals, turbochargers ...... 4b-4 Shrink joints, built-up crankshaft ...... 3-4 Shrunk joints ...... 9-1

Sigman – CTh - diagram ...... 7a-15 Size factor ...... 7a-6 Spare parts ...... 4b-4, 10-1 Speed control - diesel engine ...... 3-12 Split crankshafts ...... 3-4 Standby units ...... 2-8 III - Part 1 Index Chapter 2 GL 2012 Page 13

Starting air supply systems ...... 2-8 equipment ...... 3-18, 4a-5, 4a-7 Steering gear ...... 7b-5, 9-3 systems ...... 2-9 Stern tube bearings ...... 5-7 cast resin mounting ...... 5-8 connections ...... 5-8 Supercavitating propellers ...... 7a-11 Survivability ...... 1-2, 1-12

T Tapered mounting ...... 7a-8 Tests ...... 2-2, 2-8, 2-10, 3-5, 3-7, 4a-9, 4b-2, 5-9, 6-1, 6-8, 6-10, 6-12, 7a-10, 7a-11, 7a-14, 7b-12 Tooth couplings ...... 6-9 Torque converters ...... 6-11 Torsional vibration stresses ...... 8-4 alternating torque ...... 8-1 measurements ...... 8-5 permissible ...... 8-2 Turning appliances ...... 2-6 gear ...... 4a-6 Type approvals/tests ...... 3-7, 3-10, 4a-11, 4b-1, 4b-4, 6-9

U Uninterrupted power supply systems (UPS) ...... 2-9

V Values, for various profile shapes ...... 7a-4 Ventilation ...... 2-7, 2-10 Vibrations ...... 1-4, 3-21, 4a-5, 4a-9, 4a-13 Voice communication ...... 2-7

W Water cooling systems ...... 2-9 Water jets ...... 7a-11 Chapter 2 Index III - Part 1 Page 14 GL 2012

Watertight bulkheads ...... 2-10 doors ...... 2-10 Weather conditions ...... 2-8 Welding ...... 2-1 Works trials ...... 3-10

III - Part 1 Section 1 A General Rules and Instructions Chapter 2 GL 2012 Page 1–1

Section 1

General Rules and Instructions

A. General 6. In addition to these Rules, GL reserves the right to impose further requirements in respect of all 1. These Rules apply to the propulsion plant of types of machinery where this is unavoidable due to seagoing surface ships and craft intended for naval new findings or operational experience, or GL may activities. permit deviations from the Rules where these are specially warranted. The following types of propulsion plants are not in- cluded in these Rules: 7. Reference to further regulations and stan- – nuclear power plants dards 1 – plants with fuel cell technology 7.1 If the requirements for propulsion plants and – steam boilers for main propulsion operating agents are not defined in these Rules, the application of other regulations and standards has to – steam turbines be defined as far as necessary. – low speed diesel engines with crossheads 7.2 The regulations of the "International Conven- – reversible two-stroke diesel engines tion for the Safety of Life at Sea 1974/1978" (SOLAS), as amended are considered in these Rules – plants for operation with heavy fuel oil and its as far as they appear to be applicable to naval surface pre-treatment combat ships. The definite scope of application has to – thermal oil systems be defined in the building specification by the Naval Administration and the shipyard. However, on application, plants of a type listed above may be included in a design review and classification These Rules are also in compliance with the provi- procedure, where relevant for the overall concept of a sions of the "International Convention for the Preven- naval project. tion of Pollution from Ships" of 1973 and the relevant Protocol of 1978 (MARPOL 73/78). 2. Apart from machinery and equipment de- tailed below, these Rules are also applicable individu- 7.3 For ships of NATO states the Nato Agree- ally to other machinery and equipment where this is ment for Standardisation (STANAG) may be consid- necessary for the safety of the ship and its crew. ered besides Classification by GL. NATO and Partners for Peace Navies may adopt in 3. Designs which deviate from these Rules may addition the Naval Ship Code which provides a be approved, provided that such designs have been framework for a naval surface ship safety management recognized as equivalent. system. On request GL is prepared to check if this Code is applied for the naval ship to be classified and 4. Machinery installations which have been to assign the Class Notation NSC (Chapter) in case of developed on novel principles and/or which have not successful examination of the requirements of the yet been sufficiently tested in shipboard service re- defined Chapter(s). The detailed requirements relevant quire special GL approval. for this Chapter are summarized in Section 11. In such cases GL is entitled to require additional documentation to be submitted and special trials to be 7.4 Besides of these Rules national regulations, carried out. Such machinery may be marked by the international standards and special definitions in the Notation EXP affixed to the Character of Classifica- building specification respectively in the mission tion. statement of the actual ship have to be considered. The application of such regulations is not affected by the 5. In the instances mentioned in 3. and 4. GL is GL Rules. entitled to require additional documentation to be submitted and special trials to be carried out. 8. Design The design of the propulsion plant has to fulfil the –––––––––––––– following conditions: 1 For auxiliary power to be produced with fuel cell technology see GL Guidelines for the Use of Fuel Cell Systems on Board of Ships and Boats (VI-3-11) – Guidelines for the Use of Fuel 8.1 The operation of the naval ship and the habit- Cell Systems on Board of Ships and Boats. ual conditions provided on board as well as the func- Chapter 2 Section 1 B General Rules and Instructions III - Part 1 Page 1–2 GL 2012

tioning of all systems under the operational conditions 3. Dead ship condition of combat, wartime cruising, peacetime cruising and "Dead ship" condition means that the complete ma- in-port readiness are to be ensured at all times. chinery plant including the main source of electrical 8.2 The power distribution network shall be de- power are out of operation and auxiliary energy as signed to ensure operability in case of network failure. compressed air, starting current from batteries, etc. are not available for the restoration of the main power 8.3 The operation of certain systems and equip- supply, for the restart of the auxiliaries and for the ment, which are necessary for safety, is to be guaran- start-up of the propulsion plant. It is however assumed teed under defined emergency conditions. that special mobile or fixed equipment for start-up will be available on board of a naval ship. 8.4 The risks for crew and ship from operation of the propulsion plant shall be minimized. 4. Draught T The draught T is the vertical distance at the middle of 8.5 High working reliability shall be achieved by the length L, from base line to the deepest design simple and clearly arranged operation processes as water line, as estimated for the lifetime of the ship. well as by application of type-approved products. 5. Essential equipment 8.6 The requirements concerning design, ar- rangement, installation and operation which are de- 5.1 Essential for ship operation are all main pro- fined in the GL Rules for Classification and Surveys pulsion plants. (III-0), Electrical Installations (III-1-3a), Automation (III-1-3b) and Ship Operation Installations and Auxil- 5.2 Essential (operationally important) are the iary Systems (III-1-4), shall be fulfilled. following auxiliary machinery and plants, which: 8.7 A high degree of survivability of the ship – are necessary for propulsion and manoeuvrabil- should be achieved by redundancies in the design and ity of the ship functioning of essential equipment. – are required for maintaining ship safety 8.8 The principles of ergonomic design of ma- – are required to maintain the safety of human life chinery and equipment have to be considered. at sea as well as 8.9 Where in a class of naval ships, originally planned to be identical, deviations become necessary, – equipment according to special Characters of GL shall be duly informed and changes properly Classification and Class Notations documented. 5.3 Essential auxiliary machinery and plants are 8.10 One failure principle comprising e.g.: The single failure concept assumes that only one (sin- – generator units gle) failure is the initiating event for an undesired – steering gear plant occurrence. The simultaneous occurrence of inde- – fuel oil supply units pendent failures is not considered. – lubricating oil pumps – cooling water/cooling media pumps – starting and control-air compressor B. Definitions – starting installations for auxiliary and main engines 1. Auxiliary electrical power – charging air blowers The auxiliary electrical power [kVA] is defined as the – exhaust gas turbochargers continuous electrical power at continuous speed v0, which is not directly used for propulsion of the ship, – controllable pitch propeller installation but for driving all kinds of auxiliary devices and – azimuth drives equipment. The degree of redundancy shall be defined – engine room ventilation fans in the building specification. – steam, hot and warm water generation plants 2. Black-out condition – oil firing equipment Black-out condition means that the complete machin- – pressure vessels and heat exchangers in essential ery plant including the main source of electrical power systems are out of operation, but auxiliary energy as com- – hydraulic pumps pressed air, starting current from batteries, etc. are still available for restoration of power supply. – fuel oil treatment units III - Part 1 Section 1 C General Rules and Instructions Chapter 2 GL 2012 Page 1–3

– fuel oil transfer pumps able driving power is acting at its technically possible – lubrication oil treatment units minimum power output. – bilge and ballast pumps – heeling compensation systems – fire pumps and fire fighting equipment C. Documents for Approval

– anchor windlasses and capstans 1. All documents have to be submitted for ap- – transverse thrusters proval to GL in German or English language. – ventilation fans for hazardous areas 2. The survey of the ship's construction will be – turning gears for main engines carried out on the basis of approved documents. The – bow and stern ramps as well as shell openings, if drawings shall contain all data necessary for approval. applicable Where necessary, calculations and descriptions of the ship's elements are to be submitted. Any non-standard – bulkhead door closing equipment symbols used are to be explained in a key list. All – weapon systems (effectors) documents have to indicate the number of the project – equipment considered necessary to maintain and the name of the Naval Administration and/or endangered spaces in a safe condition shipyard. – NBC fans and passage heaters The drawings and documents have to give sufficient evidence for proving that the requirements set out in – decontamination equipment this Chapter have been complied with. – parts of the shipboard aircraft installations 3. Calculations 5.4 For ships with equipment according to spe- cial Characters of Classification and Notations certain 3.1 The supporting calculations shall contain all type-specific plants may be classed as essential equip- necessary information concerning reference docu- ment ments. Literature used for the calculations has to be cited, important but not commonly known sources 6. Rated driving power P shall be added in copy. The rated driving power [kW] is defined as continuous 3.2 The choice of computer programs according power to be delivered by the propulsion machinery to the "State of the Art" is free. The programs may be when running at rated speed v . 0 checked by GL through comparative calculations with predefined test examples. A generally valid approval 7. Ship speeds for a computer program is, however, not given by GL.

7.1 Rated speed v0 3.3 The calculations have to be compiled in a way which allows identifying and checking all steps Expected maximum, continuous ahead speed v [kn] 0 of the calculation in an easy way. Hand written, easily of the ship in calm water at the draught T, when the readable documents are acceptable. total available rated driving power is exclusively used for propulsion purposes. Comprehensive quantities of output data shall be pre- sented in graphic form. A written comment to the 7.2 Maximum speed vmax main conclusions resulting from the calculations has to be provided. Expected maximum ahead speed vmax [kn] of the ship in calm water at the draught T, when the total avail- 4. A summary of the required documents is able maximum driving power is exclusively used for contained in the GL Rules for Classification and Sur- propulsion devices. This speed is related to an over- veys (III-0), Section 4, Table 4.1. Further details are load condition, permissible only for a defined, rela- defined in the following Sections of this Chapter. tively short time period. 5. GL reserves the right to demand additional 7.3 Cruising speed v M documentation if that submitted is insufficient for an Expected economic, continuous ahead cruising speed assessment of the naval ship. This may especially be vM [kn] of the ship, which provides the maximum the case for plants and equipment related to new de- radius of action. velopments and/or which are not tested on board to a sufficient extent. 7.4 Minimum speed vmin 6. Design drawings are to be submitted to GL Expected minimum ahead speed vmin [kn] of the ship for approval. The drawings are required to contain all in calm water at the draught T, when the total avail- the details necessary to carry out an examination in Chapter 2 Section 1 D General Rules and Instructions III - Part 1 Page 1–4 GL 2012

accordance with the following requirements. To facili- The effects of elastic deformation of the ship's hull on tate a smooth and efficient approval process they the machinery installation have to be considered. should be submitted electronically via GLOBE 2. In specific cases and following prior agreement with GL 1.3 Environmental conditions they can also be submitted in paper form in triplicate. The design environmental conditions of a naval ship and the requirements for Class Notation AC1 are 7. Once the documents submitted have been defined in Table 1.2. approved by GL they are binding for the execution of the work. Subsequent modifications and extensions 2. Vibrations require the approval of GL before being put into ef- fect. 2.1 General

8. At the commissioning of the naval ship or 2.1.1 Machinery, equipment and hull structures are after considerable changes or extensions of the propul- normally subject to vibration stresses. Design, con- sion plant, the documentation for approval as defined struction and installation shall in every case take ac- in the different Sections, showing the final condition of count of these stresses. the systems, has to be given on board. All documents have to indicate the name of the ship, the newbuilding The fault-free long-term service of individual compo- number of the shipyard and the date of execution. nents shall not be endangered by vibration stresses. The operating and maintenance instruction, warning If a naval ship is designed to create only a limited signs, etc. have to be prepared in English or German influence of vibrations on the fatigue of the hull struc- language. If the user's language is different, a transla- tures, the mast mounted electronic equipment, etc. and tion into the user language has to be provided and be the habitability of the crew the Class Notation VIBR carried also on board. may be assigned. For details see GL Rules for Hull Structures and Ship Equipment (III-1-1), Section 16, C. 2.1.2 Where a machine or a piece of equipment D. Ambient Conditions generates vibrations when in operation, the intensity of the vibration shall not exceed defined limits. The 1. General operating conditions purpose is to protect the vibration generators, the connected assemblies, peripheral equipment and hull 1.1 The selection, layout and arrangement of the components from additional, excessive vibration ship's structure and all shipboard machinery shall be stresses liable to cause premature failures or malfunc- such as to ensure faultless continuous operation under tions. defined standard ambient conditions. 2.1.3 The following provisions relate to vibrations More stringent requirements are to be observed for in the frequency range from 2 to 300 Hz. The underly- Class Notation AC1 (see GL Rules for Classification ing assumption is that vibrations with oscillation fre- and Surveys (III-0), Section 2, C.). quencies below 2 Hz can be regarded as rigid-body For the Class Notation ACS variable requirements for vibrations while vibrations with oscillation frequen- unusual types and/or tasks of naval ships can be dis- cies above 300 Hz normally occur only locally and cussed case by case, but shall not be less than the may be interpreted as structure-borne noise. Where, in standard requirements. special cases, these assumptions are not valid (e.g. where the vibration is generated by a gear pump with Components in the machinery spaces or in other a tooth meshing frequency in the range above 300 Hz) spaces which comply with the conditions for the Nota- the following provisions are to be applied in analo- tions AC1 or ACS are to be approved by GL. gous manner. 1.2 Inclinations and movements of the ship 2.1.4 Attention has to be paid to vibration stresses The design conditions for static and dynamic inclina- over the whole relevant operating range of the vibra- tions of a naval ship have to be assumed independ- tion exciter. ently from each other. The standard requirements and Where the vibration is generated by an engine, consid- the requirements for Class Notation AC1 are defined eration is to be extended to the whole available work- in Table 1.1. ing speed range and, where appropriate, to the whole GL may consider deviations from the angles of incli- power range. nation defined in Table 1.1 taking into consideration type, size and service conditions of the naval ship. 2.1.5 The procedure described below is largely standardized. Basically, a substitution quantity is formed for the vibration stress or the intensity of the –––––––––––––– exciter spectrum (cf. 2.2.1). This quantity is then com- 2 Detailed information about GLOBE submission can be found pared with permissible or guaranteed values to check on GL’s website www.gl-group.com/globe. that it is admissible. III - Part 1 Section 1 D General Rules and Instructions Chapter 2 GL 2012 Page 1–5

Table 1.1 Design conditions for ship inclinations and movements

Design conditions Type of inclination and Type of movement affected equipment Standard requirements Notation AC1

Inclination athwartships: 1

Main and auxiliary machinery 15° 25°

Other installations 2 22,5° 25°

No uncontrolled switches or 45° 45° functional changes Static condition Ship's structure acc. to stability requirements acc. to stability requirements

Inclinations fore and aft: 1

Main and auxiliary machinery 5° 5°

Other installations 2 10° 10°

Ship's structure acc. to stability requirements acc. to stability requirements

Rolling: 1

Main and auxiliary machinery 22,5° 30°

Other installations 2 22,5° 30°

Pitching: 1

Main and auxiliary machinery 7,5° 10°

Other installations 2 10° 10°

Accelerations: Dynamic condition pitch: 32 °/s2 3 Vertical (pitch and heave) az [g] heave: 1,0 g

Transverse roll: 48 °/s2 3 (roll, yaw and sway) ay [g] yaw: 2 °/s2

sway: ay [g] a [g] 3 Longitudinal (surge) x a [g] 4 Combined acceleration x acceleration ellipse 3 direct calculation

1 athwartships and fore and aft inclinations may occur simultaneously 2 ship's safety equipment, switch gear and electric/electronic equipment 3 defined in the GL Rules for Hull Structures and Ship Equipment (III-1-1), Section 5, B. 4 to be defined by direct calculation

Chapter 2 Section 1 D General Rules and Instructions III - Part 1 Page 1–6 GL 2012

Table 1.2 Design environmental conditions

Design conditions Environmental area Parameters Standard requirements Notation AC1 Temperature – 25 °C to + 45 °C 1 – 30 °C to + 55 °C 1 For partially open spaces ––– – 10 °C to + 50 °C 1 Temperatures related to: – atmospheric pressure 1000 mbar 900 mbar to 1100 mbar – max. relative humidity 60 % 2 100 % 3 3 Outside the ship/ 1 mg/m 1 mg/m Salt content air withstand salt-laden spray withstand salt-laden spray Dust/sand to be considered filters to be provided Wind velocity 43 kn 3 90 kn (systems in operation) Wind velocity 86 kn 3 100 kn (systems out of operation) Temperature 4 – 2 °C to + 32 °C – 2 °C to + 35 °C Outside the ship/ Density acc. to salt content 1,025 t/m3 1,025 t/m3 seawater Flooding withstand temporarily withstand temporarily Outside the ship/ Icing on ship's surfaces up see Chapter 1, see Chapter 1, icing of surface to 20 m above waterline Section 2, B.3.4 Section 2, B.3.4 Outside the ship/ drift ice in mouth of rivers drift ice in mouth of rivers Ice class E navigation in ice and coastal regions and coastal regions

Entrance to the ship/ Air temperature – 15 °C to + 35 °C – 15 °C to + 35 °C for design of heating/ Max. heat content of the air 100 kJ/kg 100 kJ/kg cooling systems Seawater temperature – 2 °C to + 32 °C – 2 °C to + 35 °C Air temperature 0 °C to + 45 °C 0 °C to + 45 °C Atmospheric pressure 1000 mbar 1000 mbar Inside the ship/ Max. relative humidity up to 100 % (+ 45 °C) 100 % all spaces 5 Salt content 1 mg/m3 1 mg/m3 Oil vapour withstand withstand Condensation to be considered to be considered Air temperature 0 °C to + 40 °C 0 °C to + 40 °C Max. relative humidity 80 % 100 % Inside the ship/ air-conditioned areas Recommended ideal climate air temperature for manned computer spaces ––– + 20 °C to + 22 °C at 60 % rel. humidity Inside the ship/ Air temperature 0 °C to + 55 °C 0 °C to + 55 °C in electrical devices with higher degree of Max. relative humidity 100 % 100 % heat dissipation

1 higher temperatures due to radiation and absorption heat have to be considered 2 100 % for layout of electrical installations 3 for lifting devices according to the GL Guidelines for the Construction and Survey of Lifting Appliances (VI-2-2), Section 2 4 GL may approve lower limit water temperatures for ships operating only in special geographical areas 5 for recommended climatic conditions in the ship’s spaces see also GL Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 11, F.

III - Part 1 Section 1 D General Rules and Instructions Chapter 2 GL 2012 Page 1–7

in which 2.1.6 The procedure mentioned in 2.1.5 takes the physical facts into account only incompletely. The aim s = vibration displacement amplitude is to evaluate the true alternating stresses or alternat- ing forces. No simple relationship exists between the v = vibration velocity amplitude actual load and the substitution quantities: vibration amplitude, vibration velocity and vibration accelera- veff = effective value of vibration velocity tion at the external parts of the frame. Nevertheless, this procedure is adopted since at present, it appears to â = vibration acceleration amplitude be the only one which can be implemented in a rea- sonable way. For these reasons it is expressly pointed ω = angular velocity of vibration out that the magnitude of the substitution quantities applied in relation to the relevant limits enables no For any periodic oscillation with individual harmonic conclusion to be drawn concerning the reliability or components 1, 2,...n, the effective value of the vibra- load of components as far as these limits are not ex- tion velocity can be calculated by the formula: ceeded. It is, in particular, inadmissible to compare the load of components of different reciprocating ma- chines by comparing the substitution quantities meas- 22 2 veff=+++ v eff v eff ... v eff (2) ured at the engine frame. i12 n

2.1.7 For reciprocating machinery, the following in which v is the effective value of the vibration effi statements are only applicable for outputs over velocity of the i-th harmonic component. Using for- -1 100 kW and speeds below 3 000 min . mula (1), the individual values of v are to be calcu- effi 2.1.8 The special rules concerning torsional vibra- lated for each harmonic. tions according to Section 8 have to be considered. Depending on the prevailing conditions, the effective value of the vibration velocity is given by formula (1) Note for purely sinusoidal oscillations or by formula (2) for GL is prepared to carry out on request the following any periodic oscillation. calculations within the additional marine advisory services: 2.2.2 The assessment of vibration loads is gener- ally based on areas A, B and C, which are enclosed by Calculation of free vibrations with the FE-method as the boundary curves shown in Fig. 1.1. The boundary well as forced vibrations due to harmonic or shock curves of areas A, B, and C are indicated in Table 1.3. excitation. A number of pre- and post processing pro- If the vibration to be assessed comprises several har- grams is available here as well for effective analyses: monic components, the effective value according to – calculation of engine excitation forces/moments 2.2.1 is to be applied. The assessment of this value shall take account of all important harmonic compo- – calculation of propeller excitation forces (pres- nents in the range from 2 to 300 Hz. sure fluctuations and shaft bearing reactions) – calculation of hydrodynamic masses 2.2.3 Area A can be used for the assessment of all machines, equipment and appliances. Machines, – graphic evaluation of amplitude level as per ISO equipment and appliances for use on board a ship shall 6954 recommendations or as per any other stan- as a minimum requirement be designed to withstand a dard vibration load corresponding to the boundary curve of – noise predictions area A.

2.2 Assessment Otherwise, with GL's consent, steps must be taken (vibration damping, etc.) to reduce the actual vibration 2.2.1 In assessing the vibration stresses imposed on load to the permissible level. machinery, equipment and hull structures, the vibra- 2.2.4 Because they act as vibration exciters, recip- tion velocity v is generally used as a criterion for the rocating machines are to be separately considered, prevailing vibration stress. The same criterion is used because they act as vibration exciters. Both the vibra- to evaluate the intensity of the vibration spectrum tion generated by reciprocating machines and the produced by a vibration exciter (cf. 2.1.2). stresses consequently imparted to directly connected peripheral equipment (e.g. governors, exhaust gas In the case of a purely sinusoidal oscillation, the effec- turbochargers and lubricating oil pumps) and adjacent tive value of the vibration velocity veff can be calcu- machines or apparatus (e.g. generators, transmission lated by the formula: systems and pipes) can, for the purpose of these Rules and with due regard to the limitations stated in 2.1.6, 1 1 1 aˆ veff = ⋅ sˆ ⋅ ω = ⋅ vˆ = ⋅ (1) be assessed using the substitution quantities presented 2 2 2 ω in 2.2.1. Chapter 2 Section 1 D General Rules and Instructions III - Part 1 Page 1–8 GL 2012

100 Veff = 45

50 Area C Veff = 28 4 g Area B Veff = 25 B' 2,6 g ^ Area A Veff = 14 1,6 g A' 10 1,3 g Velocity v [mm/s] Velocity

0,7 g 5 Upper boundaries of areas A, B, C Upper boundaries of Area A', B'

1 2 5 10 50 100 300

Frequency [Hz]

Fig. 1.1 Areas for assessment of vibration loads

Table 1.3 Numerical definition of the area boundaries shown in Fig. 1.1

Areas A B C A' B' s [mm] < 1 < 1 < 1 < 1 < 1 v [mm/s] < 20 < 35 < 63 < 20 < 40

veff [mm/s] < 14 < 25 < 45 < 14 < 28 â [g] < 0,7 < 1,6 < 4 < 1,3 < 2,6

2.2.4.1 In every case the manufacturer of reciprocat- If the permissible vibration loads of individual directly ing machines has to guarantee permissible vibration connected peripheral appliances in accordance with loads for the important directly connected peripheral 2.2.4.1 lie below the boundary curve of area B, per- equipment. The manufacturer of the reciprocating missibility shall be proved by measurement of the machine is responsible to GL for proving that the vibration load which actually occurs. vibration loads are within the permissible limits in accordance with 2.3. 2.2.4.3 If the vibration loads of reciprocating ma- chines lie outside area A' but are still within area B', it shall be proved by measurement that directly con- 2.2.4.2 Where the vibration loads of reciprocating nected peripheral appliances are not loaded above the machines lie within the A' area, separate consideration limits for area C. or verifications relating to the directly connected pe- ripheral equipment (cf. 2.2.4) are not required. The In these circumstances directly connected peripheral same applies to machines and apparatus located in appliances shall in every case be designed for at least close proximity to the vibration exciter (2.2.4). the limit loads of area C, and machines located nearby for the limit loads of area B. In these circumstances directly connected peripheral Proof is required that machines and appliances located appliances shall in every case be designed for at least in close proximity to the main exciter are not subject the limit loads of area B', and machines located nearby to higher loads than those defined by the boundary for the limit loads of area B. curve of area B. III - Part 1 Section 1 D General Rules and Instructions Chapter 2 GL 2012 Page 1–9

If the permissible vibration loads of individual, di- which may be required concerning the level of the rectly connected peripheral appliances or machines in vibration spectrum generated by the reciprocating accordance with 2.2.4.1 lie below the stated values, machine. admissibility shall be proved by measurement of vi- bration load which actually occurs. 2.4 Measurement 2.2.4.4 If the vibration loads of reciprocating ma- chines lie outside area B' but are still within area C, it is necessary to ensure that the vibration loads on the 2.4.1 Proof based on measurements is normally directly connected peripheral appliances still remain required only for reciprocating machines with an out- within area C. If this condition cannot be met, the put of more than 100 kW, provided that the other important peripheral appliances are to be in accor- conditions set out in 2.2.4.2 – 2.2.4.4 are met. Where dance with 2.3 demonstrably designed for the higher circumstances warrant this, GL may also require loads. proofs based on measurements for smaller outputs. Suitable measures (vibration damping, etc.) are to be taken to ensure reliable prevention of excessive vibra- 2.4.2 Measurements are to be performed in every tion loads on adjacent machines and appliances. The case under realistic service conditions at the point of permissible loads stated in 2.2.4.3 (area B or a lower installation. During verification, the output supplied value specified by the manufacturer) continue to apply by the reciprocating machine shall be not less than to these units. 80 % of the rated value. The measurement shall cover the entire available speed range in order to facilitate 2.2.4.5 For directly connected peripheral appliances, the detection of any resonance phenomena. GL may approve higher values than those specified in 2.2.4.2, 2.2.4.3 and 2.2.4.4, if these are guaranteed by 2.4.3 GL may accept proofs based on measure- the manufacturer of the reciprocating machine in ac- ments which have not been performed at the point of cordance with 2.2.4.1 and are proved in accordance installation (e.g. test bed runs), but under different with 2.3. mounting conditions, provided that the transferability Analogously, the same applies to adjacent machines of the results can be proved. and appliances, if the relevant manufacturer guaran- tees higher values and provides proof of these in ac- The results are normally regarded as transferable in cordance with 2.3. the case of flexibly mounted reciprocating machines of customary design. 2.2.5 For appliances, equipment and components which, because of their installation in steering gear If the reciprocating machine is not flexibly mounted, compartments or bow thruster compartments, are the transferability of the results may still be acknowl- exposed to higher vibration stresses, the admissibility edged if the essential conditions for this (similar bed of the vibration load may, notwithstanding 2.2.3, be construction, similar installation and pipe routing, etc.) assessed according to the limits of area B. The design are satisfied. of such equipment shall allow for the above men- tioned increased loads. 2.4.4 For assessment of the vibration stresses af- 2.3 Proofs fecting or generated by reciprocating machines nor- mally the location in which the vibration loads are 2.3.1 Where in accordance with 2.2.4.1, 2.2.4.4 and greatest. Fig. 1.2 indicates the points of measurement 2.2.4.5 GL is asked to approve higher vibration load which are normally required for an inline piston en- values, all that is normally required for this is the gine. The measurement has to be performed in all binding guarantee of the admissible values by the three directions. In justified cases exceptions can be manufacturer or the supplier. made to the inclusion of all the measuring points. 2.3.2 GL reserves the right to call for detailed proofs (calculations, design documents, measurements 2.4.5 The measurements can be performed with etc.) in cases where this is warranted. mechanical manually-operated instruments provided that the instrument setting is appropriate to the meas- 2.3.3 Type approval in accordance with the GL ured values bearing in mind the measuring accuracy. Guidelines for Test Requirements for Electrical / Elec- tronic Equipment and Systems (VI-7-2), are regarded Directionally selective, linear sensors with a frequency as proof of admissibility of the tested vibration load. range of at least 2 to 300 Hz should normally be used. Non-linear sensors can also be used provided that the 2.3.4 GL may recognize long-term trouble free measurements take account of the response character- operation as sufficient proof of the required reliability istic. and operational dependability. 2.4.6 The records of the measurements for the 2.3.5 The manufacturer of the reciprocating ma- points at which the maximum loads occur are to be chine is in every case responsible to GL for any proof submitted to GL together with a tabular evaluation. Chapter 2 Section 1 F General Rules and Instructions III - Part 1 Page 1–10 GL 2012

III

II

I

3

2 1 KS 0 R L Z

Y

X

Side for L left side looking towards measurement coupling flange R right side looking towards coupling flange

Measuring 0 bed height 1 base 2 crankshaft height 3 frame top

Measuring I coupling side (KS) point over II engine centre engine III opposite side to coupling length (KGS)

Fig. 1.2 Schematic representation of in-line piston engine

3. Shock The approved materials for the different systems are defined in the following Sections. Naval ships may also be exposed to shock forces cre- ated by air or underwater explosions from conven- 1.2 Materials deviating from the defined quality tional or nuclear weapons. requirements may only be used with special approval For naval ships with special ability to withstand shock of GL. The suitability of the materials has to be loads Class Notation SHOCK may be assigned. De- proven. tails for shock requirements are described in the GL Rules for Hull Structures and Ship Equipment (III-1- 1), Section 16. F. Fuels and Consumables for Operation

E. Materials 1. All fuels and consumables used for the opera- tion of propulsion plants are to be in accordance with the requirements of the manufacturers. 1. Approved Materials The use of heavy fuel oil is not considered in these 1.1 The materials used for propulsion plants have Naval Rules. If required in exceptional cases the re- to fulfil the quality requirements defined in the GL quirements of the GL Rules for Machinery Installa- Rules for Metallic Materials (II-1) and Welding (II-3). tions (I-1-2) have to be applied. III - Part 1 Section 1 G General Rules and Instructions Chapter 2 GL 2012 Page 1–11

2. The flash point 3 of liquid fuels for the opera- 2.1 No skin contact is possible with elements tion of boilers and diesel engines may not be lower warmed up under operating conditions to surface than 60°. temperature above 70 °C.

3. In exceptional cases, for ships intended for 2.2 Components, which may be used without operation in limited geographical areas or where spe- body protection, e.g. protective gloves and with a cial precautions subject to GL approval are taken, contact time up to 5 s, are to have no higher surface fuels with flash points between 43 °C and 60 °C may temperature than 60 °C. also be used. This is conditional upon the requirement that the temperatures of the spaces in which fuels are 2.3 Components made of materials with high stored or used shall invariably be 10 °C below the thermal conductivity, which may be used without flash point. body protection and a contact time of more than 5 s are not to achieve a surface temperature above 45 °C. 4. The fuel has to be filterable. 2.4 Exhaust gas lines and other apparatus and 5. The fresh cooling water for internal combus- lines transporting hot media have to be insulated ef- tion engines has to be treated from freshwater and fectively. Insulation material has to be non-combus- corrosion protection agent. tible. Locations where inflammable liquids or mois- ture may penetrate into the insulation are to be pro- Fresh water has to comply with the requirements of tected in a suitable way by coverings, etc. the engine manufacturer with respect to: – water hardness [dGH] 3. When using hand cranks for starting internal combustion engines, steps are to be taken to ensure – pH value (at 20 °C) that the crank disengages automatically when the – chloride content [mg/l] engine starts. 6. The storage of fuel and consumables for Dead-Man's circuits are to be provided for rotating operation has to follow the requirements of the GL equipment. Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 7. 4. Blowdown and drainage facilities are to be designed in such a way that the discharged medium can be safely drained off.

G. Safety Equipment and Protective 5. In operating spaces, anti-skid floor plates and Measures floor coverings are to be used.

Machinery is to be installed and safeguarded in such a 6. Service gangways, operating platforms, way that the risk of accidents is largely ruled out. stairways and other areas open to access during opera- Besides of national regulations particular attention is tion are to be safeguarded by guard rails. The outside to be paid to the following: edges of platforms and floor areas are to be fitted with It has to be ensured that physical arrangements for coamings unless some other means is adopted to pre- machinery and equipment do not pose a risk to per- vent persons and objects from sliding off. sonnel. 7. Glass water level gauges for auxiliary steam 1. Moving parts, flywheels, chain and belt boilers are to be equipped with protection devices. drives, linkages and other components which could Devices for blowing through water level gauges shall constitute an accident hazard for the operating person- be capable of safe operation and observation. nel are to be fitted with guards to prevent contact. The same applies to hot machine parts, pipes and walls for 8. Safety valves and shutoffs are to be capable which no thermal insulation is provided, e.g. pressure of safe operation. Fixed steps, stairs or platforms are lines to air compressors. to be fitted where necessary.

2. The design and installation of all systems and 9. Safety valves are to be installed to prevent equipment has to ensure that elements, which have to the occurrence of excessive operating pressures. be used during normal operation of the ship by the crew and where no thermal insulation is provided, are 10. Steam and feedwater lines, exhaust gas ducts, kept within the following restrictions concerning acci- auxiliary boilers and other equipment and pipelines dental contact of hot surfaces. carrying steam or hot water are to be effectively insu- lated. Insulating materials are to be incombustible. –––––––––––––– Points at which combustible liquids or moisture can 3 Based, up to 60 °C, on determination of the flash point in a penetrate into the insulation are to be suitably pro- closed crucible (cup test). tected, e.g. by means of shielding. Chapter 2 Section 1 H General Rules and Instructions III - Part 1 Page 1–12 GL 2012

11. For machinery which is operated in hazard- – direct destruction of machinery, equipment or ous areas, provisions are to be established to avoid the control systems risk of ignition. These might be design measures, monitoring of criterial parameters and/or bring the – direct destruction of weapons and sensors machinery in a safe condition. – threat to the crew

2. Measures for improved survivability H. Survivability The design of a ship which is classed as naval ship has to consider a series of possible measures to improve 1. Definition survivability. These GL Rules for naval surface ships offer in the different Chapters various measures and Survivability of a naval ship is to be regarded as the Class Notations to achieve improved survivability. degree of ability to withstand a defined weapon threat The degree of including such measures in an actual and to maintain at least a basic degree of safety and project has to be defined by the Naval Administration. operability of the ship.

It is obvious that survivability is an important charac- 3. Measures for the propulsion plant teristic of a naval ship which may be endangered by: In this Chapter the following main measure to im- – loss of global strength of the hull structure prove survivability is included. – loss of buoyancy and/or stability 3.1 Redundant propulsion – loss of manoeuvrability The requirements for the Class Notations RP1 x% to – fire in the ship and ineffective fire protection or RP3 x% concerning redundant propulsion and ma- fire fighting capability noeuvrability are defined in Section 2, K. III - Part 1 Section 2 B Design and Construction of the Machinery Installation Chapter 2 GL 2012 Page 2–1

Section 2

Design and Construction of the Machinery Installation

A. General 2. Materials All components subject to these Rules shall comply 1. As far as necessary for function and safe with GL Rules II – Materials and Welding. operation, the design of the propulsion plant has to consider the size and experience of the crew according 3. Welding to the mission statement of the actual naval ship. The fabrication of welded components, the approval 2. Normally it can be assumed, that: of companies and the testing of welders are subject to GL Rules for Welding, (II-3-1) to (II-3-3). – no personnel is permanently present in machin- ery rooms 4. Screw connections – in machinery rooms inspection patrols will be made in regular time intervals 4.1 Screws are to be designed according to proven and acknowledged principles. – the machinery control centre (MCC) is perma- nently manned 4.2 The design of screw connections between equipment and foundations has to avoid shear forces 3. The operating and maintenance instructions, or bending moments in the screws, only tensional warning signs, etc. have to be prepared in English and forces in axial direction are allowed. Therefore, the in the user's language. flanges where the screw forces are acting have to be stiffened with a suitable number of brackets to avoid flange bending, which would create bending moments to the screws.

B. Dimensions of Components 4.3 Only closed holes in flanges shall be pro- vided for screws, because under shock influence 1. General screws might slip out of a hole in form of a half open slot. In addition friction connections are not safe under shock influence. 1.1 All parts are to be capable of withstanding the stresses and loads peculiar to shipboard service, Note e.g. those due to movements of the ship, vibrations, intensified corrosive attack, temperature changes and If expansion screws are used, the peak stresses at the wave impact, and shall be dimensioned in accordance core of the thread are reduced, because the maximum with the requirements set out in the present Chapter. stress will occur at the location of the reduced shaft section. If such screws are long enough, they will be The ambient conditions acc. to Section 1, D. and the able to protect the mounted equipment from shock GL Rules for Classification and Surveys (III-0), loads to some extent, because the elongation of the Electrical Installations (III-1-3a), Automation (III-1- shaft reduces acceleration peaks. 3b) and Ship Operation Installations and Auxiliary It is also recommendable to use cap nuts together with Systems (III-1-4), have to be considered. expansion screws for connections. With this form of In the absence of rules governing the dimensions of nut the load on the different turns of the thread is parts, the recognized rules of engineering practice are nearly the same, which helps to avoid excessive local to be applied. stresses. If a normal screw is fitted into a threaded hole, the 1.2 Where connections exist between systems or breaking of the screw because of the severe transverse plant items which are designed for different forces, dynamic shock loads will be evident at the first turn of pressures and temperatures (stresses), safety devices the thread coming out of the hole. This is the case are to be fitted which prevent the over-stressing of the because of the adding up of the bending stress to the system or plant item designed for the lower design maximum axial stress which occurs at this turn. The parameters. To preclude damage, such systems are to problem can be solved by a flat necking of the shaft be fitted with devices affording protection against above the last turn of the thread or by a special form excessive pressures and temperatures and/or against of shaft and hole. The bolt is in the latter case pro- overflow. vided with a small collar fitting in the upper part of Chapter 2 Section 2 E Design and Construction of the Machinery Installation III - Part 1 Page 2–2 GL 2012

the hole. Thus the biggest part of the bending stress ensured that the electrical power for emergency ser- will be transmitted at the collar and is separated from vices is available at all times. the axial stress at the thread. 2. In case of "dead ship" condition it is to be 5. Tests ensured that it will be possible for the propulsion system and all necessary auxiliary machinery to be 5.1 Machinery and its component parts are sub- restarted within a period of 30 minutes, see the GL ject to constructional and material tests, pressure and Rules for Ship Operation Installations and Auxiliary leakage tests, and trials. All the tests prescribed in the Systems (III-1-4), Section 6, A.4. following Sections are to be conducted under supervi- sion of GL. In case of parts produced in series, other methods of D. Control and Regulating testing may be agreed with GL instead of the tests prescribed, provided that the former are recognized as equivalent by GL. 1. Machinery is to be so equipped that it can be controlled in accordance with operating requirements in such a way that the service conditions prescribed by 5.2 GL reserves the right, where necessary, to the manufacturer can be met. increase the scope of tests and also to subject to test- ing those parts which are not expressly required to be tested according to the Rules. 1.1 For the control equipment of main engines and systems essential for operation see the GL Rules for Electrical Installations (III-1-3a), Automation (III- 5.3 Components subject to mandatory testing are 1-3b) and Ship Operation Installations and Auxiliary to be replaced by tested parts. Systems (III-1-4). 5.4 After installation on board of the main and 2. In the event of failure or fluctuations of the auxiliary machinery, operational functioning of the supply of electrical, pneumatic or hydraulic power to machinery including associated ancillary equipment is to be verified. All safety equipment is to be tested, regulating and control systems, or in case of a break in unless adequate testing has already been performed at a regulating or control circuit, steps are to be taken to ensure that: the manufacturer's works in the presence of the GL Representative. – the appliances remain at their present opera- tional setting or, if necessary, are changed to a In addition, the entire machinery installation is to be setting which will have the minimum adverse tested during sea trials, as far as possible under the effect on operation (fail-safe conditions) intended service conditions. – the power output or engine speed of the machin- 6. Corrosion protection ery being controlled or governed is not in- creased Parts which are exposed to corrosion are to be safe- – no unintentional start-up sequences are initiated guarded by being manufactured of corrosion-resistant materials or provided with effective corrosion protec- 3. Each driving machinery has to be provided tion. with an emergency stopping device.

4. Manual operation C. Availability of Machinery Every essential automatically or remote controlled system shall also be capable of manual operation, see 1. Ship's machinery is to be so arranged and also the requirements in the GL Rules for Automation equipped that it can be brought into operation from the (III-1-3b). "dead ship" condition with the means available on board. A manual emergency stopping device has to be pro- vided. The "dead ship" condition means that the entire ma- chinery installation including the electrical power supply is out of operation and auxiliary sources of energy such as starting air, battery-supplied starting E. Propulsion Plant current etc. are not available for restoring the ship's electrical system, restarting auxiliary operation and bringing the propulsion installation back into opera- 1. General tion. 1.1 All devices forming a part of the propulsion To overcome the "dead ship" condition use may be plant have to be provided with peripheral components made of an emergency generator set provided that it is which ensure a faultless handling as well as a simple III - Part 1 Section 2 E Design and Construction of the Machinery Installation Chapter 2 GL 2012 Page 2–3

and safe operation and control, even if they are not 2.1.5 COGOG specified in detail. COGOG is the abbreviation for COmbined Gas tur- 1.2 All auxiliary machinery and the control units bine Or Gas turbine. In this configuration a propulsion directly needed for the operation of the propulsion shaft can be driven alternatively by one or the other plant are to be located as near as possible to the driv- gas turbine, see Fig. 2.5. ing machinery. 2.1.6 CODELAG 1.3 Manoeuvring equipment CODELAG is the abbreviation for COmbined Diesel Every engine control stand is to be equipped in such a ELectric And Gasturbine. In this configuration a pro- way that: peller shaft can be driven alternatively by one or two electric motors, only by the gas turbine or by electric – the propulsion plant can be adjusted to any set- motor and gas turbine together. The electric drive will ting be chosen if the radiated noise has to be minimized – the direction of propulsion can be reversed and for cruising speed νM. The combination of electric – the propulsion unit or the propeller shaft can be motors and gas turbine has to be applied for maximum stopped speed vmax, see Fig. 2.6.

1.4 If required in the building specification, the 2.1.7 IEP driving machinery has to be designed and equipped for operation in a sound protection capsule. IEP is the abbreviation for Integrated Electric Propul- sion. In this configuration the electric power is gener- Using sound protection capsules the relative move- ated by several diesel gen sets and/or gas turbine gen ment between the driving machinery and the shipside sets. According to the actual speed requirements the piping system has to be compensated by flexible con- required power for propulsion will be delivered to the nections. If applicable, the elastic mounting of the electric propulsion motor of each propeller shaft, see driving machinery has to be taken into account. Fig. 2.7. 1.5 For connected pumps no electrically driven 2.1.8 AZP stand by pumps are to be provided if the propulsion is AZP is the abbreviation for AZimuthing Propulsion. ensured by several driving machines. In this configuration the electric power is generated by 1.6 The remote control of the propulsion plant several diesel gen sets and/or gas turbine gen sets. The from the bridge is subject to the GL Rules for Auto- drive of the propulsors is done directly by electric mation (III-1-3b). motors in the azimuthing pods (without transmitting shaft), see Fig. 2.8. 2. Multiple-shaft and multi-engine systems 2.2 If a ship is equipped with several propulsion machines, it shall be possible to disengage the different 2.1 Definitions propulsion engines from the power transmitting unit. 2.1.1 CODAD At manual or automatic emergency stops of an engine, the relevant clutch has to disconnect automatically. CODAD is the abbreviation for COmbined Diesel engine And Diesel engine. In this configuration a 2.3 Steps are to be taken to ensure that in the propulsion shaft can be driven alternatively by one event of a failure of a propulsion engine, operation can diesel engine or several diesel engines, see Fig. 2.1. be maintained with remaining engines, where appro- priate by a simple change-over system. 2.1.2 CODAG CODAG is the abbreviation for COmbined Diesel 2.4 Multiple shaft systems engine And Gas turbine. In this configuration a pro- A space separation between driving engines and driv- pulsion shaft can be driven alternatively by a diesel ing gear shall be provided, if possible. engine or by a gas turbine or by both, see Fig. 2.2. All necessary provisions have to be made, that: 2.1.3 CODOG – only one propulsion shaft can be used and no CODOG is the abbreviation for COmbined Diesel overloading occurs engine Or Gas turbine. In this configuration a propul- – starting and operation is possible with every sion shaft can be driven alternatively by a diesel en- driving engine intended to drive a propulsion gine or a gas turbine, see Fig. 2.3. shaft, independently from the other propulsion shafts 2.1.4 COGAG For Class Notation redundant propulsion (RP) see K. COGAG is the abbreviation for COmbined Gas tur- bine And Gas turbine. In this configuration a propul- For multiple-shaft systems, each shaft is to be pro- sion shaft can be driven alternatively by one gas tur- vided with a locking device which prevents dragging bine or by several gas turbines, see Fig. 2.4. of the shaft. Chapter 2 Section 2 E Design and Construction of the Machinery Installation III - Part 1 Page 2–4 GL 2012

Fig. 2.1 Principle arrangement for CODAD propulsion plants

Fig. 2.2 Principle arrangement for CODAG propulsion plants

Fig. 2.3 Principle arrangement for CODOG propulsion plants

Fig. 2.4 Principle arrangement for COGAG propulsion plants III - Part 1 Section 2 E Design and Construction of the Machinery Installation Chapter 2 GL 2012 Page 2–5

Fig. 2.5 Principle arrangement for COGOG propulsion plants

M G

G M

Fig. 2.6 Principle arrangement for CODELAG plants

M G G

G G M

Fig. 2.7 Principle arrangement for Integrated Electric Propulsion (IEP)

M G G

G G M

Fig. 2.8 Principle arrangement for Azimuthing Propulsors (AZP) Chapter 2 Section 2 I Design and Construction of the Machinery Installation III - Part 1 Page 2–6 GL 2012

Explanation of symbols used in Figures 2.1 to 2.8 I. Engine Room Equipment

1. Operating and monitoring equipment Diesel engine 1.1 Instruments, warning and indicating systems and operating appliances are to be clearly displayed gas turbine and conveniently sited. Absence of dazzle, particularly on the bridge, is to be ensured. electric generator G Operating and monitoring equipment is to be grouped in such a way as to facilitate easy supervision and M electric motor control of all important parts of the installation. The following requirements are to be observed when clutch installing systems and equipment: – protection against humidity and the effects of dirt bulkhead penetration of shafts – avoidance of excessive temperature variations – adequate ventilation In consoles and cabinets containing electrical or hy- draulic equipment or lines carrying steam or water the F. Turning Appliances electrical gear is to be protected from damage due to leakage. 1. Machinery is to be equipped with suitable and adequately dimensioned turning appliances. Redundant ventilation systems are to be provided for air-conditioned machinery and control rooms. 2. The turning appliances are to be of self- locking type. Electric motors are to be fitted with 1.2 Pressure gauges suitable retaining brakes. The scales of pressure gauges are to be dimensioned up to the specified test pressure. The maximum per- 3. An automatic interlocking device is to be mitted operating pressures are to be marked on the provided to ensure that the propulsion and auxiliary pressure gauges for boilers, pressure vessels and in prime movers cannot start up while the turning gear is systems protected by safety valves engaged. In case of manual turning installations warn- ing devices may be provided alternatively. Pressure gauges are to be installed in such a way that they can be isolated. Lines leading to pressure gauges are to be installed in such a way that the readings cannot be affected by G. Operating and Maintenance Instructions liquid heads and hydraulic hammer.

Manufacturers of machinery, boilers and auxiliary 2. Accessibility of machinery and boilers equipment shall supply a sufficient number of operat- ing and maintenance notices and manuals together 2.1 Machinery and boiler installations, appara- with the equipment. tuses, control and operating devices are to be easily accessible and visible for operation and maintenance. In addition, an easily legible board is to be mounted National regulations have to be observed. on boiler operating platforms giving the most impor- tant operating instructions for boilers and oil-firing 2.2 In the layout of machinery spaces (design of equipment. foundation structures, laying of pipelines and cable conduits, etc.) and for the design of machinery and equipment (mountings for filters, coolers, etc.) 2.1 is to be complied with. H. Markings, Identification For the installation and the dismantling of the propul- sion machinery, openings of sufficient size have to be In order to avoid unnecessary operating and switching provided; for all other parts of the equipment installa- errors, all parts of the machinery whose function is not tion and dismantling routes have to be planned. immediately apparent are to be adequately marked and labelled. Fixtures for transport devices have to be provided. III - Part 1 Section 2 K Design and Construction of the Machinery Installation Chapter 2 GL 2012 Page 2–7

The installation of components within the installation Local control stations are to be equipped with an routes has to be avoided or the components are to be emergency telegraph. dismountable. 4. Shaft revolution indicator 3. Machinery control centre The speed and direction of rotation of the propeller Machinery control centres (MCC) are to be provided shafts are to be indicated on the bridge, in the engine with at least two exits, one of which can also be used room respectively in all control stations. In the case of as an escape route. small propulsion units, the indicator may be dispensed with. 4. Lighting Barred speed ranges are to be marked on the shaft All operating spaces are to be adequately lit to ensure revolution indicators. that control and monitoring instruments can be easily read. In this connection see the rules defined in the GL 5. Design of communication and signalling Rules for Electrical Installation (III-1-3a), Section 11. equipment Reversing, command transmission and operating con- 5. Bilge wells/ bilges trols, etc. are to be grouped together at a convenient See rules defined in the GL Rules for Ship Operation point at the control stations. Installations and Auxiliary Systems (III-1-4), Section The current status, "Ahead" or "Astern", of the revers- 8. ing control is to be clearly indicated on the propulsion plant at the control stations. 6. Ventilation Signalling devices are to be clearly perceptible from The design and construction of ventilation systems all parts of the engine room when the machinery is in are subject to the requirements defined in the GL full operation. Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 11. For details of the design of electrically operated com- mand transmission, signalling and alarm systems, see 7. Noise abatement GL Rules for Electrical Installations (III-1-3a) and Automation (III-1-3b). In compliance with the relevant national regulations, care is to be taken to ensure that operation of the ship is not unacceptably impaired by engine noise, e.g. by means of shielding. K. Redundant Systems

1. General

J. Communication and Signalling Equipment 1.1 The GL Rules concerning Redundant Propul- sion and Steering Systems (I-1-14) apply to ships, 1. Voice communication which are classified by GL and are to receive the No- Means of voice communication are to be provided tation RP1 x%, RP2 x% or RP3 x% affixed to the between the ship's manoeuvring station, the engine Character of Classification. room and the steering gear compartment, and these In the following an overview for general information means shall allow fully satisfactory intercommunica- about these Rules shall be given. tion independent from the shipboard power supply under all operating conditions (see also GL Rules for 1.2 The Rules for redundant propulsion and Electrical Installations (III-1-3a), Section 9). steering systems stipulate the level of redundancy for the propulsion and steering systems. It is characterised 2. Duty alarm system by the appropriate Notation to be affixed to the Charac- ter of Classification as defined in the GL Rules for From the engine room or the machinery control centre Classification and Surveys (III-0), Section 3, C. a duty alarm system for the engineer officers has to be established for the off-duty period. See also GL Rules 1.3 The Rules are based on the single-failure for Electrical Installations (III-1-3a), Section 9, C.5. concept.

3. Engine telegraph 1.4 Documents for approval Machinery operated from the engine room is to be 1.4.1 Compliance in accordance with the Notation equipped with a telegraph. applied for is to be demonstrated by block diagrams, In the case of multiple-shaft installations, a telegraph schematic drawings, descriptions of system functions is to be provided for each unit. and operation, calculations and arrangement plans. Chapter 2 Section 2 K Design and Construction of the Machinery Installation III - Part 1 Page 2–8 GL 2012

Model tests or calculations shall be used to show the weather conditions 2 has to be at least 7 knots or half speed and manoeuvring qualities that have to be at- the speed v0 (the lower value may be applied), tained during sea trials in order to demonstrate com- pliance with the requirements set out in 2. 2.3 the requirements stated in 2.1 and 2.2 can be met for a minimum period of 72 hours 3. 1.4.2 A failure mode and effects analysis (FMEA) or an equivalent analysis is to be conducted for the propulsion and steering systems, and for the auxiliary 2.4 the requirements stated in 2.1, 2.2 and 2.3 can systems and control systems needed to operate them. be met irrespective of the ship's loading condition, The analysis shall demonstrate that a single failure 2.5 the redundant propulsion systems and steer- cannot lead to any loss in propulsion and/or in steering ing systems are ready for operation at any time and ability in accordance with the requirements set out in 2. can be activated on demand, The analysis shall further demonstrate that measures are in place for failure detection and control of possi- 2.6 the redundant propulsion system is capable of ble effects and that these measures are adequate to taking up operation from a still standing propulsion ensure in particular that the propulsion and steering of plant. the ship can be rapidly restored. Compliance with the above requirements is to be dem- In addition, the analysis has to deal with the identifica- onstrated by calculations and/or model tests and veri- tion of possible failure conditions, which have a com- fied in a suitable manner during sea trials. mon cause. The identification of technical elements and/or operational procedures, which could undermine 3. Requirements for auxiliary systems the redundancy concept, shall also be accounted for. 3.1 Auxiliary systems for redundant propulsion For the Notation RP1 x%, the FMEA only has to be systems whose function have a direct effect on the performed for the redundant propulsion machines and propulsion system, for example fuel, lubrication oil, their requisite auxiliary systems. The events of water cooling water, control air and uninterrupted power ingress or fire in a machinery compartment, and a supply systems, are to be provided for each propulsion failure of any of the common elements of the propul- system independently of each other. sion train related to this Notation do not have to be considered. Where standby units are specified for these systems in accordance with GL Rules, these shall be provided for For the Notation RP2 x%, the FMEA has to be per- each of the systems in question. formed for the redundant propulsion and steering systems and their requisite auxiliary systems. The 3.2 Auxiliary systems for redundant propulsion events of water ingress or fire in a machinery com- systems which failure do not have a direct effect on partment and water ingress in a steering gear com- the propulsion system, such as fuel treatment, starting partment do not have to be considered. air supply systems, etc. are to be designed to be sepa- rate from each other. For these systems no additional 1.4.3 A programme of tests to be conducted during standby units have to be provided if interconnection sea trials is to be submitted for approval. lines are provided between the systems and if the units are designed so that the propulsion systems can be 2. General requirements supplied with power simultaneously without restric- tion. In the connection lines shut-off valves are to be In accordance with the requirements set out in these provided which have to be kept closed during normal Rules, it shall be ensured that when a failure in a pro- operation. pulsion or steering system occurs, On ships with Class Notation RP3 x%, a shut-off 2.1 the manoeuvrability of the ship can be main- valve is to be fitted on either side of the partition bulk- tained so that even under unfavourable weather condi- head between the machinery compartments. tions 1 the ship can be manoeuvred into a position of less resistance to the weather and can be maintained in this position,

2.2 a minimum speed can be maintained to keep the ship under control and ensure that it is able to make speed over the ground in waters where there is a –––––––––––––– strong current. The minimum speed under normal 2 Normal weather conditions are regarded as being a wind speed of up to and including 11 m/s (5 on the Beaufort scale) and a –––––––––––––– significant wave height of 2,8 m with an average wave period of 6,7 s. 1 Within the context of these Rules, unfavourable weather conditions are regarded as being a wind speed of up to and in- 3 For ships, which normally spend less than 72 hours cruising at cluding 21 m/s (8 on the Beaufort scale) and a significant wave sea, the period specified may be limited to the maximum time height of 5,4 m with an average wave period of 8,3 s. of a voyage. III - Part 1 Section 2 K Design and Construction of the Machinery Installation Chapter 2 GL 2012 Page 2–9

3.3 In fuel oil systems, the heating facilities for All equipment, which is primary essential for opera- preheating the fuel oil are to be designed so that if one tion, shall be connected to at least two switchboards of propulsion system fails, the required preheating of the electrical power generating plants. fuel oil for the redundant propulsion system can be The two switchboards shall be capable of being con- ensured. trolled and monitored independently of each other. It is not necessary to provide a redundant heating Transitional power supplies necessary for this purpose facility if diesel oil storage tanks are provided which have to be of redundant design. allow unrestricted operation for the redundant propul- Where power management systems are required to sion system for the period of time specified in 2.3. provide a reliable power supply to the propulsion systems, these shall also be of redundant design. 3.4 Supply lines from fuel oil service tanks of redundant propulsion systems shall be provided with an interconnection fitted between service tank and 4. Control and monitoring systems pump of each system. The interconnection is to be provided with a shut-off device, which is to be kept 4.1 Controls closed during normal operation. 4.1.1 The redundant propulsion system is to be On ships with Class Notation RP3 x%, a shut-off capable of being controlled by means of a simple valve has to be fitted on either side of the partition control from the ship’s bridge. A local control shall bulkhead between the machinery compartments. also be provided for emergency operation.

3.5 The seawater supply of redundant propulsion 4.1.2 Common controls, e.g. joystick controls that systems may be achieved via a common sea chest operate redundant propulsion systems are to be de- connection by means of a pump assigned to each pro- signed so that a single failure does not affect an intact pulsion system. The systems shall be capable of being system, and the control remains possible without re- isolated by means of a shut-off valve in the connection striction by means of another method of control (indi- line. vidual control or emergency control).

On ships with Class Notation RP3 x% the sea chests 4.1.3 In the case of multiple propulsion systems, a are to be installed in separate compartments in accor- central emergency control facility is to be provided, dance with 6.1. The shut-off valve in the connection for example from the machinery control room, at line is to be fitted to the partition bulkhead and be which it is possible to adjust the speed and direction of capable of being operated either from both machinery rotation of the propulsion machines centrally. compartments or from a position outside the machin- ery compartments. 4.2 Monitoring devices 3.6 On ships with Class Notation RP3 x% it The redundant propulsion machines and their auxiliary shall be possible to operate the redundant propulsion systems are to be monitored by independent alarms. system when one of the seawater cooling systems Alarms and status indicators are to be provided. fails, in accordance with the compartment separation requirements specified in 6.1. 5. Requirements for steering systems

3.7 Electric propulsion 5.1 Rudders

3.7.1 In electric propulsion systems the main and Every redundant steering system shall consist of a excitation converter systems, and where appropriate, main and an auxiliary steering gear, each with inde- their supply transformers, their protection and control pendent control. facilities and the corresponding Uninterrupted power The rudder position is to be indicated by means of supply systems (UPS) is to be designed in such a way electrically independent rudder position indicators. that the redundant propulsion power of the ship re- mains available when a single failure occurs. Auxil- The ship's steering capability is to be ensured even iary systems (e.g. re-cooling devices and auxiliary when the rudder is blocked at maximum deflection. If power supplies) are to be designed so that they are the steering ability is impaired to the extent that the separate from one another. requirements set out in 2. cannot be met, it shall be possible to move and lock the failed rudder into the midships position. 3.8 Redundant electric propulsion systems of naval ships shall be supplied from the switchboards of 5.2 Azimuthing propulsor units as steering at least two electrical power generation plants, which systems are linked by an interconnection feeder. If one of the switchboard fails, the remaining one shall supply the Where ship steering is exclusively performed by azi- propulsion system and its auxiliary power supplies, muthing propulsor systems, at least two azimuth pro- compare the GL Rules for Electrical Installations (III- pulsion systems are to be provided, each with inde- 1-3a), Section 4, H. pendent controls. Chapter 2 Section 2 K Design and Construction of the Machinery Installation III - Part 1 Page 2–10 GL 2012

6.1.4 Watertight doors may be permitted in accor- The position of the individual azimuthing propulsor dance with SOLAS II-1 / Reg. 18 or Reg. 15 respec- systems shall be indicated by electrically independent tively. These have to be equipped with an open/closed indicators. status indication and a remote control facility on the If the ship's steering ability is impaired, even when a bridge. defective azimuthing propulsor is disconnected, to the extent that the requirements stated in 2. cannot be met, Watertight doors are not to be regarded as emergency it shall be possible to move and to lock the defective exits for machinery compartments. propulsor into the midships position. 6.2 Ventilation For all further details see Section 7b. Machinery compartments are to be fitted with inde- 6. Compartment separation requirements for pendent ventilation systems. RP3 x% 7. Tests 6.1 Bulkheads and partitions Tests are to be performed during sea trials in accor- 6.1.1 Redundant propulsion systems and steering dance with an approved sea trial program. The tests systems are to be separated from each other by water- are designed to prove that: tight bulkheads. – the ship is able to meet the requirements defined

6.1.2 Partitions between machinery compartments – the propulsion and steering systems have the containing redundant propulsion systems have to com- necessary redundancy in line with the Notation ply with a fire resistance, the level of which depends applied for on the fire potential of the machinery compartments. – the conclusions drawn in the FMEA regarding The partitions have to keep their structural integrity in the effects of failure conditions and measures to case of fire for at least 60 minutes. Fire insulation detect and control these failure conditions are shall be provided if the function of essential machin- correct and adequate ery and equipment could be adversely affected. 8. Full information 6.1.3 Partition walls of machinery compartments, which are isolated from each other by tanks, coffer- The full and binding requirements concerning redun- dams or other void spaces, have to keep their struc- dant systems are defined in the GL Rules for tural integrity in case of fire for at least 60 minutes. Redundant Propulsion and Steering Systems (I-1-14). III - Part 1 Section 3 A Internal Combustion Engines Chapter 2 GL 2012 Page 3–1

Section 3

Internal Combustion Engines

A. General after installation on board overload power cannot be given delivered. The limitation of the fuel delivery 1. Scope system has to be secured permanently.

The Rules contained in this Section are valid for inter- 3.6 Subject to the prescribed conditions, diesel nal combustion engines as main and auxiliary drives. engines driving electric generators are to be capable of Internal combustion engines in the sense of these overload operation even after installation on board. Rules are four-stroke diesel engines with trunk piston. 3.7 Subject to the approval by GL, diesel engines 2. Ambient conditions may be designed for a continuous power (fuel stop power) which cannot be exceeded. For all engines, which are used on ships with unre- stricted range of service, the definition of the perform- 3.8 For main engines, a power diagram (Fig. 3.1) ance has to be based on the ambient conditions ac- is to be prepared showing the power ranges within cording to Section 1, D. which the engine is able to operate continuously and The defined seawater temperature has especially to be for short periods under service conditions. considered as inlet temperature to coolers for charge air coolant operating with seawater. Overload power Nominal propeller 3. Rated power 3 curve Rated 3.1 Diesel engines are to be designed such that (continuous) their rated power when running at rated speed accord- power ing to the definitions of the engine manufacturer at 2 1 ambient conditions as defined in Section 1, D. can be Ranges: delivered as continuous power. Diesel engines are to 1 = for continuous be capable of continuous operation within power operation Power [%] or [kW] range c in Fig. 3.1 and intermittently in power 2 = for short-period range d. The extent of the power ranges are to be operation stated by the engine manufacturer. Engine speed [%] or [min-1] 3 = for exceptional operation 3.2 Continuous power is to be understood as the standard service power which an engine is capable of delivering continuously, provided that the mainte- Fig. 3.1 Example of a power diagram nance prescribed by the engine manufacturer is carried out, between the maintenance intervals stated by the 4. Fuels engine manufacturer.

3.3 To verify that an engine is rated at its con- 4.1 The use of liquid fuels is subject to the re- tinuous power, it is to be demonstrated that the engine quirements contained in Section 1, F. can run at an overload power corresponding to 110 % of its rated power at corresponding speed for an unin- 4.2 For fuel treatment and supply, see the GL terrupted period of 1 hour. Deviations from the over- Rules for Ship Operation Installations and Auxiliary load power value require the agreement of GL. Systems (III-1-4), Section 7, B. and Section 8, G.

3.4 Engines, which have to meet the require- 5. Accessibility of engines ments of a permanent low-load operation according to the mission statement of the naval ship, have to be Engines are to be so arranged in the engine room that designed with regard to bad combustion and low tem- all the assembly holes and inspection ports provided peratures. Relevant measures and additional equip- by the engine manufacturer for inspections and main- ment have to be approved by GL. tenance are accessible. A change of components, as far as practicable on board, shall be possible. Re- 3.5 After running on the test bed, the fuel deliv- quirements related to space and construction have to ery system of main engines is to be so adjusted that be considered for the installation of the engines. Chapter 2 Section 3 B Internal Combustion Engines III - Part 1 Page 3–2 GL 2012

6. Electronic components and systems cases and following prior agreement with GL they can also be submitted in paper form in triplicate. 6.1 For electronic components and systems which are necessary for the control of internal com- Where considered necessary, GL may request further bustion engines the following items have to be ob- documents to be submitted. This also applies to the served: documentation of design changes according to 4.

6.1.1 Electronic components and systems have to 2. Engines manufactured under license be type approved according to the GL Rules for Test Requirements for Electrical / Electronic Equipment For each engine type manufactured under licence, the and Systems (VI-7-2). licensee shall submit to GL Head Office, as a mini- mum requirement, the following documents: 6.1.2 For computer system the GL Rules for Electrical Installations (III-1-3a), Section 10 have to – comparison of all the drawings and documents be observed. as per Table 3.1 - where applicable - indicating the relevant drawings used by the licensee and 6.1.3 For main propulsion engines one failure of an the licensor electronic control system shall not result in a total loss or sudden change of the propulsion power. In individ- – all drawings of modified components, if avail- ual cases, GL may approve other failure conditions, able, as per Table 3.1 together with the licen- whereby it is ensured that no increase in ship's speed sor's declaration of consent to the modifications occurs. – a complete set of drawings at the disposal of the 6.1.4 The non-critical behaviour in case of a failure local inspection office of GL as a basis for the of an electronic control system has to be proven by a performance of tests and inspections structured analysis (e.g. FMEA), which has to be provided by the system's manufacturer. This investiga- 3. Definition of a Diesel engine type tion shall include the effects on persons, environment and technical condition. The type specification of an internal combustion en- gine is defined by the following data: 6.1.5 Where the electronic control system incorpo- rates a speed control, F.2.3 of this Section and – manufacturer's type designation Electrical Installations (III-1-3a), Section 9 have to be – cylinder bore observed. – stroke 6.2 Local control station – method of injection 6.2.1 For the local control station, H. has to be – fuels which can be used observed. – working cycle (4-stroke) 6.2.2 The indicators named in H. shall be realised in such a way that one failure can only affect a single – method of gas exchange (naturally aspirated or indicator. Where these indicators are an integral part supercharged) of an electronic control system, means shall be taken – rated power per cylinder at rated speed as well to maintain these indications in case of failure of such as mean effective pressure, mean indicated pres- a system. sure and maximum firing pressure 6.2.3 Where these indicators are realised electri- – method of pressure charging (pulsating pressure cally, the power supply of the instruments and of the system or constant-pressure system) electronic system has to be realised in such way to – charge air cooling system ensure the behaviour stated in 6.2.2. – cylinder arrangement (in-line, vee)

4. Design modifications B. Documents for Approval Following initial approval of an engine type by GL, 1. For each engine type the drawings and docu- only those documents listed in Table 3.1 require to be ments listed in Table 3.1 shall, wherever applicable, resubmitted for examination which embody important be submitted by the engine manufacturer to GL for design modifications. approval (A) or information (R). To facilitate a smooth and efficient approval process they shall be submitted electronically via GLOBE 1. In specific 5. Approval of engine components –––––––––––––– The approval of exhaust gas turbochargers, heat ex- 1 Detailed information about GLOBE submission can be found changers, engine-driven pumps, etc. is to be requested on GL’s website www.gl-group.com/globe. from GL by the respective manufacturer. III - Part 1 Section 3 B Internal Combustion Engines Chapter 2 GL 2012 Page 3–3

Table 3.1 Documents for approval Seria A/R Description Quantit Remarks lNo. y (see below) Details required on GL forms F 144 and F 144/1 when applying for 1 R 3 approval of an internal combustion engine 2 R Engine transverse cross-section 3 3 R Engine longitudinal section 3 Bedplate or crankcase 4 R – cast 1 A – welded, with welding details and instructions 3 9 5 A Thrust bearing assembly 3 3 Thrust bearing base plate: 6 R – cast 1 A – welded, with welding details and instructions 3 9 Frame/framebox 7 R – cast 1 1 A – welded, with welding details and instructions 3 1, 9 8 R Tie rod 1 9 R Cylinder cover/head, assembly 1 10 R Cylinder liner 1 Crankshaft for each number of cylinders, with data sheets for calculation 11 A 3 of crankshafts 12 A Crankshaft assembly, for each number of cylinders 3 13 A Thrust shaft or intermediate shaft (if integral with engine) 3 14 A Shaft coupling bolts 3 15 A Counterweights including fastening bolts 3 16 R Connecting rod, details 3 17 R Connecting rod, assembly 3 18 R Piston assembly 1 19 R Camshaft drive, assembly 1 Material specifications of main parts with information on non- 20 A 3 8 destructive material tests and pressure tests 21 A Arrangement of foundation bolts (for main engines only) 3 22 A Schematic layout or other equivalent documents of starting air system 3 6 23 A Schematic layout or other equivalent documents of fuel oil system 3 6 Schematic layout or other equivalent documents of lubricating oil 24 A 3 6 system 25 A Schematic layout or other equivalent documents of cooling water system 3 6 26 A Schematic diagram of engine control and safety system 3 6 27 A Schematic diagram of electronic components and systems 28 R Shielding and insulation of exhaust pipes, assembly 1 29 A Shielding of high-pressure fuel pipes, assembly 3 4 30 A Arrangement of crankcase explosion relief valves 3 5 31 R Additional equipment for continuous low load operation 7 32 R Operation and service manuals 1 7 Schematic layout or other equivalent documents of hydraulic system on 33 A 3 the engine 34 A Type test program and type test report 1 35 A High pressure parts for fuel oil injection system 3 10 36 A Oil mist detection, monitoring and alarm system 3 Schematic layout or other equivalent documents of exhaust and charging 37 A 3 6 air system Chapter 2 Section 3 D Internal Combustion Engines III - Part 1 Page 3–4 GL 2012

Table 3.1 Documents for approval (continued)

A for approval R for reference

1 only for one cylinder 2 only necessary if sufficient details are not shown on the transverse cross section and longitudinal section 3 if integral with engine and not integrated in the bedplate 4 for all engines 5 only for engines with a bore > 200 mm, or a crankcase volume ≥ 0,6 m3 6 and the system, where this is supplied by the engine manufacturer. If engines incorporate electronic control systems a failure mode and effect analysis (FMEA) is to be submitted to demonstrate that failure of an electronic control system will not result in the loss of essential services for the operation of the engine and that operation of the engines will not be lost or degraded beyond acceptable performance criteria of the engine. 7 operation and service manuals are to contain maintenance requirements (servicing and repair) including details of any special tools and gauges that are to be used with their fittings/settings together with any test requirements on completion of maintenance. 8 for comparison with GL requirements for material, NDT and pressure testing as applicable 9 The weld procedure specification is to include details of pre and post weld heat treatment, welding consumables and fit-up conditions. 10 The documentation has to contain specifications of pressures, pipe dimensions and materials.

C. Crankshaft Calculation 3.2 Power-end flange couplings The bolts used to connect power-end flange couplings 1. Design methods are normally to be designed as fitted bolts in accor- dance with Section 5, D.4. 1.1 Crankshafts shall be designed to withstand If the use of fitted bolts is not feasible, GL may agree the stresses occurring when the engine runs at rated to the use of an equivalent frictional resistance trans- power. Calculations are to be based on the GL mission. In these cases the corresponding calculations Guidelines for the Calculation of Crankshafts for In- are to be submitted for approval. ternal Combustion Engines (VI-4-2). Engines, as amended. Other methods of calculation may be used 4. Torsional vibrations, critical speeds Section 8 provided that they do not result in crankshaft dimen- applies. sions smaller than those obtained by applying the aforementioned regulations. The documentation has to be submitted for approval. D. Materials

1.2 Outside the end bearings, crankshafts de- 1. Approved materials signed according to the requirements specified in 1.1 1.1 The mechanical characteristics of materials may be adapted to the diameter of the adjoining shaft used for the components of Diesel engines shall con- by a generous fillet (r ≥ 0,06 ⋅ d) or a taper. form to GL Rules for Steel and Iron Materials (II-1-2). The materials approved for the various components 1.3 Design methods for application to crank- are shown in Table 3.3 together with their minimum shafts of special construction and to the crankshafts of required characteristics and material Certificates. engines of special type are to be agreed with GL. 1.2 Materials with properties deviating from those specified may be used only with GL's special 2. Shrink joints of built-up crankshafts approval. GL requires proof of the suitability of such materials. The shrink joints of built-up crankshafts are to be designed in accordance with the GL Guidelines as 1.3 If shock loads gain great importance for the defined in 1.1 naval ship, cast iron with lamellar graphit (GG) is not recommendable for components exposed to such loads. It may only be used if it is proven that the shock 3. Screw joints loads are sufficiently reduced by adequate mountings.

2. Testing of materials 3.1 Split crankshafts 2.1 In the case of individually produced engines, Only fitted bolts may be used for assembling split the following parts are to be subjected to material tests crankshafts. in the presence of the GL representative. III - Part 1 Section 3 D Internal Combustion Engines Chapter 2 GL 2012 Page 3–5

1. Crankshaft – cylinder covers 2. Crankshaft coupling flange for main power – main bearings transmission (if not forged to crankshaft) – connecting rod bearings 3. Crankshaft coupling bolts 14. Camshaft drive gear wheels and chain wheels 4. Pistons or piston crowns made of steel, cast steel made of steel or cast steel. or nodular cast iron 2.1.1 Materials tests are to be performed in accor- 5 Connecting rod dance with Table 3.2. 6. Cylinder liners made of steel or cast steel 7. Cylinder covers made of steel or cast steel Table 3.2 Material tests 8. Welded bedplates: Parts to be tested – plates and bearing transverse girders made of (numbered according Cylinder bore forged or cast steel to the list under 9. Welded frames and crankcases D.2.1 above) 10. Welded entablatures ≤ 300 mm 1 – 5 - 8 – 9 – 10 – 11 11. Tie rods 1 – 5 -6 – 7 – 8 – 9 – 10 > 300 ≤ 400 mm 12. Exhaust gas turbocharger, see Section 4b –11 – 13 13. Bolts and studs for: > 400 mm all parts

Table 3.3 Approved materials and type of test certificate ** Test certificate GL Rules * Components A B C Section 3, C. Crankshafts × – –

Forged steel: Section 3, B. Connecting rods × – – 2 Rm ≥ 360 N/mm Pistons and piston crowns × 3 × 4 – Cylinder covers/heads × – – Camshaft drive wheels × 3 × 4 – Rolled or forged steel rounds: Tie rods × – – 2 Section 3, B. 1 2 Rm ≥ 360 N/mm Bolts and studs × × – Special grade cast steel: 2 Section 4, C. Rm ≥ 440 N/mm Throws and webs of built- × – – Special grade forged steel: up crankshafts 2 Section 3, C. Rm ≥ 440 N/mm Bearing transverse girders × – – (weldable) Cast steel Section 4, B. Pistons and piston crowns × 3 × 4 – Cylinder covers/heads × 1 × 2 – Camshaft drive wheels × 3 × 4 – Engine blocks – × 1 – Bedplates – × 1 – Nodular cast iron, preferably Cylinder blocks – × 1 – ferritic grades: Section 5, B. Pistons and piston crowns × 3 × 4 – 2 Rm ≥ 370 N/mm Cylinder covers/heads – × 1 – Flywheels – × 1 – Valve bodies – × 1 – Engine blocks – – × Bedplates – – × Lamellar cast iron: Cylinder blocks – – × 2 Section 5, C. Rm ≥ 200 N/mm Cylinder liners – – × Cylinder covers/heads – – × Flywheels – – ×

Chapter 2 Section 3 D Internal Combustion Engines III - Part 1 Page 3–6 GL 2012

Table 3.3 Approved materials and type of test certificate (continued)

** Test certificate GL Rules * Components A B C Shipbuilding steel, all GL grades for plates ≤ 35 mm in thickness Section 1, B. Welded bedplates × – – Shipbuilding steel, GL grade B Welded frames × – – for plates > 35 mm in thickness Welded housings × – – Structural steel, unalloyed, for Section 1, C. welded assemblies * all details refer to GL Rules for Steel and Iron Materials (II-1-2) ** Test Certificates according to GL Rules for Principles and Test Procedures (II-1-1), Section 1, H. with the following abbreviations: 1 only for cylinder bores > 300 mm A : GL Material Certificate 2 for cylinder bores ≤ 300 mm B : Manufacturer Inspection Certificate 3 only for cylinder bores > 400 mm C : Manufacturer Test Report 4 for cylinder bores ≤ 400 mm

2.1.2 In addition, material tests are to be carried points, to be agreed between the GL Surveyor and the out on pipes and parts of the starting air system and manufacturer, where experience shows that defects other pressure systems forming part of the engine, see are liable to occur. the GL Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 8. 2.2.2 Ultrasonic tests are to be carried out by the manufacturer in accordance with Table 3.5, and the 2.1.3 Materials for charge air coolers are to be corresponding signed manufacturer's Certificates are supplied with Manufacturer Test Report. to be submitted.

2.2 In the case of individually manufactured 2.2.3 Welded seams of important engine compo- engines, non-destructive material tests are to be per- nents may be required to be subjected to approved formed on the parts listed below in accordance with methods of testing. Tables 3.4 and 3.5: 2.2.4 Where there is reason to doubt the faultless 1. Steel castings for bedplates, e.g. bearing trans- quality of any engine component, non-destructive verse girders, including their welded joints testing by approved methods may be required in addition to the tests mentioned above. 2. Solid forged crankshafts 2.3 Crankshafts welded together from forged or 3. Cast, rolled or forged parts of fully built crank- shafts cast parts are subject to GL special approval. Both the manufacturers and the welding process shall be ap- 4. Cast or forged parts of semi-built crankshafts proved. The materials and the welds are to be tested. 5. Connecting rods Table 3.4 Magnetic particle tests 6. Piston crowns of steel or cast steel Parts to be tested 7. Tie rods (at each thread over a distance corre- Cylinder bore (numbered according to sponding to twice the threaded length) the list under D.2.2) 8. Bolts which are subjected to alternating ≤ 400 mm 1 – 2 – 3 – 4 – 5 loads, e.g.: > 400 mm all parts – main bearing bolts

– connecting rod bolts Table 3.5 Ultrasonic tests – cylinder cover bolts 9. Cylinder covers made of steel or cast steel Parts to be tested Cylinder bore (numbered according to 10. Camshaft drive gear wheels made of steel or the list under D.2.2) cast steel ≤ 400 mm 1 – 2 – 3 – 4 – 6 - 9 2.2.1 Magnetic particle or dye penetrant tests are > 400 mm 1 – 2 – 3 – 4 – 5 –6 – 9 – 10 to be performed in accordance with Table 3.4 at those III - Part 1 Section 3 E Internal Combustion Engines Chapter 2 GL 2012 Page 3–7

E. Tests and Trials 2. Manufacturing inspections

1. Approval of engine manufacturer’s work- 2.1 In general, the manufacture of engines with shops GL Classification is subject to supervision by GL. The scope of supervision should be agreed between 1.1 Every workshop where engines are assem- manufacturer and GL. bled and tested has to be approved by GL when: 2.2 Where engine manufacturers have been – the workshop is newly set up, approved by GL as "Suppliers of Mass Produced – a new production line is started, Engines", these engines are to be tested in accordance with the GL Guidelines for Mass Produced Engines – a new engine type is introduced, or (VI-4-1) – a new production process is implemented. 3. Pressure tests

1.2 Requirements for approval of engine manu- The individual components of internal combustion facturer’s workshops: engines are to be subjected to pressure tests at the pressures specified in Table 3.6. GL Certificates are – The manufacturer’s works are to be audited by to be issued for the results of the pressure tests. GL.

– Manufacturer’s works have to have suitable 4. Type approval testing (TAT) production and testing facilities, competent staff and a quality management system, which ensures a uniform production quality of the 4.1 General products according to the specification. Engines for installation on board ship shall have been type tested by GL. For this purpose a type approval Note test in accordance with 4.1.2 is to be performed.

– Manufacturing plants shall be equipped in such 4.1.1 Preconditions for type approval testing a way that all materials and components can be machined and manufactured to a specified Preconditions for type approval testing are that: standard. Production facilities and assembly lines, including machining units, welding proc- – the engine to be tested conforms to the specific esses, special tools, special devices, assembly requirements for the series and has been suita- and testing rigs as well as lifting and transpor- bly optimized tation devices shall be suitable for the type and size of engine, its components, and the purpose – the inspections and measurements necessary for intended. Materials and components shall be reliable continuous operation have been per- manufactured in compliance with all produc- formed during works tests carried out by the tion and quality instructions specified by the engine manufacturer and GL has been informed manufacturer and recognised by GL. of the results of the major inspections

– Suitable test bed facilities for load tests have to – GL has issued the necessary approval of draw- be provided, if required also for dynamic re- ings on the basis of the documents to be sub- sponse testing. All liquids used for testing pur- mitted in accordance with B. poses such as fuel oil, lubrication oil and cool- ing water shall be suitable for the purpose in- 4.1.2 Scope of type approval testing tended, e.g. they shall be clean, preheated if necessary and cause no harm to engine parts. The type approval test is subdivided into three stages, namely: – Trained personnel shall be available for pro- duction of parts, assembly, testing and partly – Stage A - Internal tests dismantling for shipping, if applicable. Functional tests and collection of operating – Storage, reassembly and testing processes for values including test hours during the internal diesel engines at shipyards shall be such that tests, which are to be presented to GL during the risk of damage to the engine or its parts is the type test. minimized. – Stage B - Type test – Engine manufacturer’s workshops shall have in place a Quality Management System recog- This test is to be performed in the presence of nized by GL. the GL’s representative. Chapter 2 Section 3 E Internal Combustion Engines III - Part 1 Page 3–8 GL 2012

Table 3.6 Pressure tests 1

2 Component Test pressure, pp [bar]

Cylinder cover, cooling water space 3 7 Cylinder liner, over whole length of cooling water space 5 7 2 Cylinder jacket, cooling water space 4, at least 1,5 ⋅ pe,zul

Exhaust valve, cooling water space 4, at least 1,5 ⋅ pe,zul

Pump body, pressure side 1,5 ⋅ pe,zul or pe,zul + 300 (whichever is less)

Fuel injection system Valves 1,5 ⋅ pe,zul or pe,zul + 300 (whichever is less)

Pipes 1,5 ⋅ pe,zul or pe,zul + 300 (whichever is less) Hydraulic system High pressure piping for hydraulic drive of exhaust gas 1,5 ⋅ pe,zul valves

Exhaust gas turbocharger, cooling water space 4, at least 1,5 ⋅ pe,zul

Exhaust gas line, cooling water space 4, at least 1,5 ⋅ pe,zul 4 Coolers, both sides 4, at least 1,5 ⋅ pe,zul

Engine-driven pumps (oil, water, fuel and bilge pumps) 4, at least 1,5 ⋅ pe,zul

Starting and control air system before installation 1,5 ⋅ pe,zul

1 In general, items are to be tested by hydraulic pressure. Where design or testing features may require modification of these test requirements, special arrangements may be agreed. 2 pe, zul [bar] = maximum working pressure in the part concerned 3 For forged steel cylinder covers test methods other than pressure testing may be accepted, e.g. suitable non-destructive examination and dimensional control properly recorded. 4 Charge air coolers need only be tested on the water side. 5 For centrifugally cast cylinder liners, the pressure test can be replaced by a crack test.

– Stage C – Component inspection The limit points of the permissible operating range as defined by the engine manufacturer are to be tested. After conclusion of the tests, major components are to be presented for inspection 4.2.2 Emergency operation situations The operating hours of the engine components For turbocharged engines the achievable output in which are presented for inspection after type case of turbocharger damage is to be determined as testing in accordance with 4.4 are to be stated. follows: 4.2 Stage A - Internal tests – for engines with one turbocharger, when rotor is blocked or removed Functional tests and the collection of operating data are to be performed during the internal tests. The – for engines with two or more turbochargers, engine is to be operated at the load points important when the damaged turbocharger is shut-off for the engine manufacturer and the pertaining oper- ating values are to be recorded. The load points are to Note be selected according to the range of application of The engine manufacturer is to state whether the the engine. achievable output is continuous. If there is a time 4.2.1 Normal operating conditions limit, the permissible operating time is to be indi- This includes the load points 25 %, 50 %, 75 %, cated. 100 % and 110 % of the rated power: 4.3 Stage B - Type test a) along the nominal (theoretical) propeller curve and/or at constant speed for propulsion engines During the type test all the tests listed under 4.3.1 to b) at rated speed with constant governor setting 4.3.3 are to be carried out in the presence of GL’s for generator drive representative. The results achieved are to be re- III - Part 1 Section 3 E Internal Combustion Engines Chapter 2 GL 2012 Page 3–9

corded and signed by GL’s representative. Deviations ure of its independent cylinder lubrication, proof of from this program, if any, require the agreement of this shall be included in the type test. GL. 4.3.1.1 Rated power (continuous power) 4.3.1 Load points The rated power is defined as 100 % output at 100 % Load points at which the engine is to be operated are torque and 100 % speed (rated speed) corresponding to conform to the power/speed diagram in Fig. 3.2. to load point 1. 4.3.1.2 100 % power Overload power 110 105,8 The operation point 100 % output at maximum al-

110 3 3a 100 lowable speed corresponding to load point 2 has to be Rated power performed. (continuous power) 100 3 90 4.3.1.3 Maximum permissible torque 12 The maximum permissible torque normally results at 4 90 110 % output at 100 % speed corresponding to load 80 point 3 or at maximum permissible power (normally 110 %) at a speed according to the nominal propeller 80 5 6 70 curve corresponding to load point 3a. 9 4.3.1.4 Minimum permissible speed for intermit- 70 2 60 tent operation The minimum permissible speed for intermittent 60

operation has to be adjusted: Power [%] 50 [%] Torque Nominal propeller curve 7 1 – at 100 % torque corresponding to load point 4 50 10 – at 90 % torque corresponding to load point 5 40 40 4.3.1.5 Part-load operation For part-load operation the operation points 75 %, 30 30 50 %, 25 % of the rated power at speeds according to the nominal propeller curve at load points 6, 7 and 8 8 11 and proceeding from the nominal speed at constant governor setting has to be adjusted corresponding to Speed [%] 100 103,2 load points 9, 10 and 11. 1 = Range of continuous operation 4.3.1.6 Continuous low-load operation 2 = Range of intermittent operation

3 = Range of short-time overload operation It has to be proven that the requirements of A.3.4 are in special applications fulfilled. The type and the scope of tests as specified by the manufacturer have to be approved by GL. Fig. 3.2 Power/speed diagram 4.3.2 Emergency operation The data to be measured and recorded when testing The maximum achievable power when operating in the engine at various load points must include all the accordance with 4.2.2 has to be performed: parameters necessary for an assessment. – at speed conforming to nominal propeller curve The operating time per load point depends on the engine size and on the time for collection of the oper- – with constant governor setting for rated speed ating values. The measurements shall in every case only be performed after achievement of steady-state 4.3.3 Functional tests condition. Functional tests to be carried out as follows: Normally, an operating time of 0,5 hour can be as- – ascertainment of lowest engine speed according sumed per load point. to the nominal propeller curve At 100 % output (rated power) in accordance with – starting tests 4.3.1.1 an operating time of 2 hours is required. At least two sets of readings are to be taken at an inter- – governor test val of 1 hour in each case. – test of the safety system particularly for over- If an engine can continue to operate without its op- speed, oil mist and failure of the lubricating oil erational safety being affected in the event of a fail- pressure Chapter 2 Section 3 E Internal Combustion Engines III - Part 1 Page 3–10 GL 2012

– test of electronic components and systems 4.8 Power increase according to the test program approved by GL If the rated power (continuous power) of a type tested – for electronically controlled diesel engines and operationally proven engine is increased by more integration tests to demonstrate that the re- than 10 %, a new type test is required. Approval of sponse of the complete mechanical, hydraulic the power increase includes examination of the rele- and electronic system is as predicted for all in- vant drawings. tended operational modes. The scope of these tests shall be proposed by the manufac- 5. Works trials turer/licensor based on the FMEA required in Table 3.1 and agreed by GL. 5.1 Application

4.4 Stage C – Component inspection In general, engines are to be subjected to trials on the test bed at the manufacturer's works and under GL Immediately after the test run the components of one supervision. The scope of these trials shall be as cylinder for in-line engines and two cylinders for V- specified below. Exceptions to this require the engines are to be presented for inspection as follows: agreement of GL. – piston, removed and dismantled 5.2 Scope of works trials – crank bearing and main bearing, removed During the trials the operating values corresponding – cylinder liner in the installed condition to each load point are to be measured and recorded by the engine manufacturer. All the results are to be – cylinder cover/head, valves disassembled compiled in an acceptance protocol to be issued by the engine manufacturer. – camshaft, camshaft drive and crankcase with opened covers In each case all measurements conducted at the vari- ous load points shall be carried out under steady Note operating conditions. The readings for 100 % power (rated power at rated speed) are to be taken twice at If deemed necessary by the GL’s representative, an interval of at least 30 minutes. further dismantling of the engine may be required. 5.2.1 Main engines for electrical propeller drive 4.5 Type approval test report The test is to be performed at rated speed with a con- The results of the type approval test are to be incor- stant governor setting under conditions of: porated in a report which is to be handed to GL. a) 100 % power (rated power): 4.6 Type approval Certificate for at least 60 minutes after reaching the steady- state condition After successful conclusion of the test and appraisal of the required documents GL issues a Type Ap- b) 110 % power: proval Certificate. for 30 minutes after reaching the steady-state condition This Type Approval Certificate is valid for a period of 5 years. Note Validity may be renewed on application by the en- After the test bed trials the output of engines driving gine designer. generators is to be so adjusted that overload (110 %) power can be supplied in service after installation on board in such a way that the governing characteris- 4.7 Type test of mass produced engines tics and the requirements of the generator protection devices can be fulfilled at all times (see A.3.6). 4.7.1 For engines with cylinder bores ≤ 300 mm which are to be manufactured in series and for which c) 75 %, 50 % and 25 % power and idle run Approval as Mass Produced Engines is sought, the d) start-up tests, see the GL Rules for Ship Opera- type test shall be carried out in accordance with the tion Installations and Auxiliary Systems (III-1- GL Guidelines for Mass Produced Engines (VI-4-1). 4), Section 6, A.2.4 4.7.2 For the performance of the type test, the e) test of governor and independent overspeed engine is to be fitted with all the prescribed items of protection device equipment. If the engine, when on the test bed, can- f) test of engine shut-down devices not be fully equipped in accordance with the re- quirements, the equipment may be demonstrated on g) test of oil mist detection or alternative system, another engine of the same series. if available III - Part 1 Section 3 E Internal Combustion Engines Chapter 2 GL 2012 Page 3–11

5.2.2 Auxiliary driving engines and engines f) in reverse direction of propeller rotation at a driving electric generators minimum speed of 70 % rated engine speed: The tests have to be performed according to 4.2.2. 10 minutes For testing of diesel generator sets, see also the GL g) testing of the monitoring and safety systems Rules for Electrical Installations (III-1-3a), Section 17, D.3.2. 6.1.2 Main propulsion engines driving control- lable pitch propellers or reversing gears 5.3 Depending on the type of plant concerned, GL reserves the right to call for a special test sched- 6.1.1 applies as appropriate. ule. Controllable pitch propellers are to be tested with various propeller pitches. Where provision is made 5.4 In the case of engines driving electric gen- for combinator operation, the combinator curves are erators the rated electrical power as specified by the to be plotted and verified by measurements. manufacturer is to be verified as minimum power. 6.1.3 Main engines driving generators for pro- 5.5 Integration tests pulsion For electronically controlled diesel engines integra- The tests are to be performed at rated speed with a tion tests shall be conducted to demonstrate that the constant governor setting under conditions of response of the complete mechanical, hydraulic and electronic system is as predicted for all intended a) 100 % power (rated propulsion power): operational modes. The scope of these tests shall be for at least 4 hours proposed by the manufacturer/licensor based on the and FMEA required in Table 3.1 and agreed by GL. at normal continuous cruise power 5.6 Component inspection for at least 2 hours After the testrun randomly selected components shall be presented for inspection. b) 110 % power: The crankshaft web deflection is to be checked. for at least 30 minutes c) in reverse direction of propeller rotation at a 6. Shipboard trials (dock and sea trials) minimum speed of 70 % of the nominal propel- ler speed After the conclusion of the running-in programme prescribed by the engine manufacturer engines are to for 10 minutes undergo the trials specified below. See also the GL Guidelines for Sea Trials of Motor Vessels (VI-11-3). d) starting manoeuvres, see the GL Rules for Ship Operation Installations and Auxiliary Systems 6.1 Scope of sea trials (III-1-4), Section 6, A.2.4 e) testing of the monitoring and safety systems 6.1.1 Main propulsion engines driving fixed propellers Note The tests have to be carried out as follows: Tests are to be based on the rated powers of the a) at rated engine speed: driven generators. for at least 4 hours 6.1.4 Engines driving auxiliaries and electrical and generators at engine speed corresponding to normal cruise These engines are to be subjected to an operational power: test for at least four hours. During the test the set concerned is required to operate at its rated power for for at least 2 hours an extended period. b) at 103 % rated engine speed: It is to be demonstrated that the engine is capable of for 30 minutes supplying 110 % of its rated power, and in the case of where the engine adjustment permits (see shipboard generating sets account shall be taken of A.3.5) the times needed to actuate the generator's overload protection system. c) determination of the minimum on-load speed. d) continuous low load operation, if applicable 6.2 The suitability of main and auxiliary engines to burn special fuels is to be demonstrated if the ma- e) starting and reversing manoeuvres chinery installation is designed to burn such fuels. Chapter 2 Section 3 F Internal Combustion Engines III - Part 1 Page 3–12 GL 2012

6.3 The scope of the shipboard trials may be shall be equipped with an overspeed protection de- extended in consideration of special operating condi- vice independent of the normal governor which pre- tions such as low-load operation, towing, etc. vents the engine speed from exceeding the rated speed by more than 15 %. 6.4 Earthing 2.2.3 The diesel engine shall be suitable and de- It is necessary to ensure that the limits specified for signed for the special requirements of the ship's elec- main engines by the engine manufacturers for the trical system. difference in electrical potential (Voltage) between the crankshaft/shafting and the hull are not exceeded Where two stage load application is required, the in service. Appropriate earthing devices including following procedure is to be applied: Sudden loading limit value monitoring of the permitted voltage po- from no-load to 50 %, followed by the remaining tential are to be provided. 50 % of the rated generator power, duly observing the requirements of 2.2.1 and 2.2.4. Application of the load in more than two steps, see Fig. 3.3, is acceptable on condition that: F. Safety Devices – the design of the ship's electrical system en- 1. General ables the use of such generator sets The Rules of Electrical Installations (III-1-3a) have to – load application in more than two steps is pro- be observed. For automated propulsion plants the vided in the design of the ship's electrical sys- Rules of Automation (III-1-3b) have to be considered tem and is approved when the drawings are re- additionally. viewed – during shipboard trials the functional tests are 2. Speed control and engine protection against overspeed carried out without objections. Here the loading of the ship’s electrical net while sequentially connecting essential equipment after break- 2.1 Main and auxiliary engines down and during recovery of the net is to be 2.1.1 Each diesel engine not used to drive an elec- taken into account. tric generator shall be equipped with a speed gover- – the safety of the ship's electrical system in the nor or regulator so adjusted that the engine speed event of parallel generator operation and failure cannot exceed the rated speed by more than 15 %. of a generator is to be demonstrated 2.1.2 In addition to the normal governor, each 2.2.4 Speed shall be stabilized and in steady-state main engine with a rated power of 220 kW or over condition within five seconds, inside the permissible which can be declutched in service or which drives a range for the permanent speed variation δr. variable-pitch propeller shall be fitted with an inde- The steady-state condition is considered to have been pendent overspeed protection device so adjusted that reached when the permanent speed variation does not the engine speed cannot exceed the rated speed by exceed ± 1 % of the speed associated with the set more than 20 %. power. Equivalent equipment may be approved by GL. 2.2.5 The characteristic curves of the governors of 2.2 Engines driving electric generators diesel engines of generator sets operating in parallel shall not exhibit deviations larger than those specified 2.2.1 Each diesel engine used to drive an electric in the GL Rules for Electrical Installations (III-1-3a), main or emergency generator shall be fitted with a Section 1, F.1. governor which will prevent transient frequency variations in the electrical network in excess of 2.2.6 Generator sets which are installed to serve ± 10 % of the rated frequency with a recovery time to stand-by circuits are to satisfy the corresponding steady state conditions not exceeding 5 seconds when requirements even when the engine is cold. It is as- the maximum electrical step load is switched on or sumed that the start-up and loading sequence is to be off. completed in about 30 seconds. In the case when a step load equivalent to the rated 2.2.7 Emergency generator sets shall satisfy the output of the generator is switched off, a transient above governor conditions also unlimited with the speed variation in excess of 10 % of the rated speed start-up and loading sequence having to be concluded may be acceptable, provided this does not cause the in about 45 seconds. intervention of the overspeed device as required by 2.1.1. 2.2.8 The governors of the engines mentioned in 2.2 shall enable the rated speed to be adjusted over 2.2.2 In addition to the normal governor, each the entire power range with a maximum deviation of diesel engine with a rated power of 220 kW or over 5 %. III - Part 1 Section 3 F Internal Combustion Engines Chapter 2 GL 2012 Page 3–13

100

90

80 limiting curve for 3rd load step 70 60 limiting curve for 50 2nd load step

40 limiting curve for 30 1st load step 20

10 Load increase referred to rated power [%] 0 6 8 10 12 14 16 18 20 22 24

Mean eff. working pressure pe,e [bar] at rated power of diesel engine

Fig. 3.3 Limiting curves for loading of diesel engines step by step from no load to rated power as function of the brake mean effective pressure

2.2.9 The rate of speed variation of the adjusting The regulating conditions required for each individ- mechanisms shall permit satisfactory synchronization ual application as described in 2.1 and 2.2 are to be in a sufficiently short time. The speed characteristic satisfied by the governor system. should be as linear as possible over the whole power range. The permanent deviation from the theoretical Electronic governors and the associated actuators are linearity of the speed characteristic may, in the case subject to type testing. of generating sets intended for parallel operation, in For the power supply, see the GL Rules for Electrical no range exceed 1 % of the rated speed. Installations (III-1-3a).

Notes relating to 2.1 and 2.2: 2.3.2 Requirements applying to main engines For single engine plants it has to be ensured that in a) The rated power and the corresponding rated case of a failure of the governor or actuator the con- speed relate to the conditions under which the trol of the engine can be taken over by another con- engines are operated in the system concerned. trol device. To ensure continuous speed control or immediate resumption of control after a fault, at least b) An independent overspeed protection device one of the following requirements is to be satisfied: means a system all of whose component parts, a) the governor system has an independent back- including the drive, work independently of the up system normal governor. b) there is a redundant governor assembly for man- ual change-over with a separately protected 2.3 Use of electrical/electronic governors power supply c) the engine has a manually operated fuel admis- sion control system suitable for manoeuvring 2.3.1 The governor and the associated actuator shall, for controlling the respective engine, be suit- For multiple engine propulsion plants requirements in able for the operating conditions laid down in the Section 2, E.2. are to be observed. Construction Rules and for the requirements specified by the engine manufacturer. For single propulsion In the event of a fault in the governor system, the drives it has to be ensured that in case of a failure of operating condition of the engine shall not become the governor or actuator the control of the engine can dangerous, that is, the engine speed and power shall be taken over by another control device. not increase. Chapter 2 Section 3 F Internal Combustion Engines III - Part 1 Page 3–14 GL 2012

Alarms to indicate faults in the governor system are lation arrangements that will be used on an engine to be fitted. according to the requirements defined in the GL Guidelines for Test Requirements for Components 2.3.3 Requirements applying to auxiliary en- and Systems of Mechanical Engineering and Off- gines for driving generators shore Technology (VI-7-8). Each auxiliary engine shall be equipped with its own governor system. 5.1.2 Safety valves to safeguard against overpres- sure in the crankcase are to be fitted to all engines In the event of a fault of components or functions with a cylinder bore of > 200 mm and/or a crankcase which are essential for the speed control in the gov- volume of ≥ 0,6 m3. ernor system, the speed demand output shall be set to “0” (i.e. the fuel admission in the injection pumps All separated spaces within the crankcase, e.g. gear shall be set to "0"). Alarms to indicate faults in the or chain casings for camshafts or similar drives, are governor system are to be fitted. to be equipped with additional safety devices if the volume of these spaces exceeds 0,6 m3. 2.3.4 The special conditions necessary to start operation from the dead ship condition are to be ob- 5.1.3 Engines with a cylinder bore of > 200 mm served, see the GL Rules for Ship Operation Installa- and ≤ 250 mm are to be equipped with at least one tions and Auxiliary Systems (III-1-4), Section 6, A.4. relief valve at each end of the crankcase. If the crank- shaft has more than 8 throws, an additional relief 3. Cylinder overpressure warning device valve is to be fitted near the middle of the crankcase. Engines with a cylinder bore of > 250 mm and 3.1 All the cylinders of engines with a cylinder bore of > 230 mm are to be fitted with cylinder over- ≤ 300 mm are to have at least one safety valve close pressure warning devices. The response threshold of to every second crank throw, subject to a minimum these warning devices shall be set at not more than number of two. 40 % above the combustion pressure at the rated Engines with a cylinder bore of > 300 mm are to have power. at least one safety valve close to each crank throw.

3.2 A warning device may be dispensed with if 5.1.4 Each safety valve shall have a free cross- it is ensured by an appropriate engine design or by sectional area of at least 45 cm2. control functions that an increased cylinder pressure cannot create danger. The total relief area of the safety valves fitted to an engine to safeguard against overpressure in the crank- 4. Crankcase airing and venting case shall not be less than 115 cm2/m3 of crankcase volume. 4.1 Crankcase airing Notes relating to 5.1.2 and 5.1.3 The airing of crankcases and any arrangement which could produce air intake within the crankcase is not a) In estimating the gross volume of the crankcase, allowed. the volume of the fixed parts which it contains may be deducted. 4.2 Crankcase venting b) A space communicating with the crankcase via a 4.2.1 Where crankcase venting systems are pro- total free cross-sectional area of > 115 cm2/m3 of vided their clear opening is to be dimensioned as volume need not be considered as a separate small as possible. space.

4.2.2 Where provision has been made for extract- c) Each relief valve required may be replaced by not ing the lubricating oil mist, e.g. for monitoring the oil more than two relief valves of smaller cross- mist concentration, the vacuum in the crankcase may sectional area provided that the free cross- not exceed 2,5 mbar. sectional area of each safety valve is not less than 45 cm2. 4.2.3 The vent pipes and oil drain pipes of two or more engines shall not be combined. Exemptions 5.1.5 The safety devices are to be quick acting and may be approved if an interaction of the combined self closing devices to relief a crankcase of pressure systems is inhibited by suitable means. at a crankcase explosion. In service they shall be oiltight when closed and have to prevent air inrush 5. Crankcase safety devices into the crankcase. The gas flow caused by the re- sponse of the safety device shall be deflected, e. g. by 5.1 Relief valves means of a baffle plate, in such a way as not to en- danger persons standing nearby. It has to be demon- 5.1.1 Crankcase safety devices have to be type strated that the baffle plate does not adversely affect approved in a configuration that represents the instal- the operational effectiveness of the device. III - Part 1 Section 3 F Internal Combustion Engines Chapter 2 GL 2012 Page 3–15

For relief valves the discs are to be made of ductile Guidelines for Test Requirements for Components material capable of withstanding the shock load at the and Systems of Mechanical Engineering and Off- full open position of the valve. shore Technology (VI-7-8), the electrical part hast to be type approved according to the GL Guidelines for Relief valves shall be fully opened at a differential Test Requirements for Electrical / Electronic Equip- pressure in the crankcase not greater than 0,2 bar. ment and Systems (VI-7-2). 5.1.6 The relief valves are to be provided with a flame arrester that permits crankcase pressure relief 5.3.4 The oil mist detector is to be installed in and prevents passage of flame following a crankcase accordance with the engine designer’s and the system explosion. manufacturer’s instructions and recommendations.

5.1.7 Safety devices are to be provided with suit- 5.3.5 Function tests are to be performed on the able markings that include the following information: engine test bed at manufacturer’s workshop and on board under the conditions of "engine at standstill" – name and address of manufacturer and "engine running at normal operating conditions" – designation and size in accordance with test procedures to be agreed with GL. – relief area – month/year of manufacture 5.3.6 Alarms and shut-downs for the detector are to be in accordance with Table 3.7. – approved installation orientation 5.3.7 Functional failures at the devices and equip- 5.1.8 Safety devices are to be provided with a ment are to be alarmed. manufacturer’s installation and maintenance manual that is pertinent to the size and type of device as well as on the installation on the engine. A copy of this 5.3.8 The oil mist detector has to indicate that the manual is to be kept on board of the ship. installed lens, which is used in determination of the oil mist concentration has been partly obscured to a 5.1.9 Plans showing details and arrangements of degree that will affect the reliability of the informa- safety devices are to be submitted for approval. tion and alarm indication.

5.2 Crankcase doors and sight holes 5.3.9 Where the detector includes the use of pro- grammable electronic systems, the arrangements are 5.2.1 Crankcase doors and their fittings shall be so in accordance with the requirements of the GL Rules dimensioned as not to suffer permanent deformation for Electrical Installations (III-1-3a), Section 10. due to the overpressure occurring during the response of the safety equipment. 5.3.10 Where sequential oil mist detection/moni- toring arrangements are provided, the sampling fre- 5.2.2 Crankcase doors and hinged inspection ports quency and time are to be as short as reasonably are to be equipped with appropriate latches to effec- practicable. tively prevent unintended closing. 5.3.11 Plans of showing details and arrangements 5.2.3 A warning notice is to be fitted either on the of the oil mist detector are to be submitted for ap- control stand or, preferably, on a crankcase door on proval. The following particulars are to be included each side of the engine. The warning notice is to in the documentation: specify that the crankcase doors or sight holes are not to be opened before a reasonable time, sufficient to – Schematic layout of engine oil mist detector permit adequate cooling after stopping the engine. showing location of engine crankcase sample points and piping arrangement together with 5.3 Oil mist detection/monitoring and alarm pipe dimensions to detector/monitor. system (Oil mist detector) – Evidence of study to justify the selected loca- 5.3.1 Engines with a cylinder diameter > 300 mm tion of sample points and sample extraction rate or a rated power of 2250 kW and above are to be (if applicable) in consideration of the crankcase fitted with crankcase oil mist detectors or alternative arrangements and geometry and the predicted systems. crankcase atmosphere where oil mist can ac- cumulate. 5.3.2 For multiple engine installations each engine is to be provided with a separate oil mist detector and – maintenance and test manuals a dedicated alarm. – information about type approval of the detec- 5.3.3 Oil mist detectors are to be type approved. tion/monitoring system or functional tests at the The mechanical requirements are defined in the GL particular engine Chapter 2 Section 3 G Internal Combustion Engines III - Part 1 Page 3–16 GL 2012

5.3.12 A copy of the documentation supplied with down the engine in the event of failure of the lubri- the system such as maintenance and test manuals are cating oil supply. Exceptions to this rule are engines to be provided on board ship. driving emergency generator sets and emergency fire pumps. For these engines an alarm has to be pro- 5.3.13 The readings and the alarm information from vided. the oil mist detector are to be capable of being read from a safe location away from the engine.

5.3.14 Where alternative methods are provided for G. Auxiliary Systems the prevention of build-up a potentially explosive condition within the crankcase (independent of the 1. General reason, e.g. oil mist, gas, hot spots, etc.), details are to be submitted for consideration of GL. The following For peripheral piping systems and accessory filter information is to be included in the details to be sub- arrangements see the GL Rules for Ship Operation mitted for approval: Installations and Auxiliary Systems (III-1-4), Section 8. – engine particulars - type, power, speed, stroke, bore and crankcase volume 2. Fuel oil system – details of arrangements preventing the build-up of potentially explosive conditions within the 2.1 General crankcase, e.g. bearing temperature monitoring, oil splash temperature, crankcase pressure 2.1.1 Only pipe connections with metal sealing monitoring, recirculation arrangements, crank- surfaces or equivalent pipe connections of approved case atmosphere monitoring design may be used for fuel injection lines. – evidence that the arrangements are effective in 2.1.2 Feed and return lines are to be designed in preventing the build-up of potentially explosive such a way that no unacceptable pressure surges conditions together with details of in service occur in the fuel supply system. Where necessary, the experience engines are to be fitted with surge dampers approved – operating instructions and maintenance and test by GL. instructions 2.1.3 All components of the fuel system are to be 5.4 Active safety measures designed to withstand the maximum peak pressures which will be expected in the system. Where it is proposed to use alternative active tech- nologies to minimise the risk for a potential crank- 2.1.4 If fuel oil reservoirs or dampers with a lim- case explosion, details of the arrangement and the ited life cycle are fitted in the fuel oil system the life function description are to be submitted to GL for cycle together with overhaul instructions is to be approval. specified by the engine manufacturer in the corre- sponding manuals. 6. Safety devices in the starting air system 2.1.5 Oil fuel lines are not to be located immedi- The following equipment is to be fitted to safeguard ately above or near units of high temperature steam the starting air system against explosions due to fail- pipelines, exhaust manifolds, silencers or other ure of starting valves: equipment required to be insulated according to 7.1 6.1 An isolation non-return valve is to be fitted As far as practicable, oil fuel lines are to be arranged to the starting air line serving each engine. far apart from hot surfaces, electrical installations or other potential sources of ignition and are to be 6.2 Engines with cylinder bores of > 230 mm screened or otherwise suitably protected to avoid oil are to be equipped with flame arrestors as follows: spray or oil leakage onto the sources of ignition. The number of joints in such piping systems are to be kept a) on directly reversible engines immediately in to a minimum. front of the start-up valve of each cylinder 2.2 Shielding b) on non-reversible engines, immediately in front of the intake of the main starting air line to 2.2.1 Regardless of the intended use and location each engine of internal combustion engines, all external fuel in- jection lines (high pressure lines between injection 6.3 Equivalent safety devices may be approved pumps and injection valves) are to be shielded by by GL. jacket pipes in such a way that any leaking fuel is: 7. Safety devices in the lubricating oil system – safely collected Each engine with a rated power of 220 kW or over is – drained away unpressurized to be fitted with devices which automatically shut – efficiently monitored and alarmed III - Part 1 Section 3 G Internal Combustion Engines Chapter 2 GL 2012 Page 3–17

2.2.2 If pressure variations of > 20 bar occur in 3.6 Oil filters fitted parallel for the purpose of fuel feed and return lines, these lines are also to be enabling cleaning without disturbing oil supply to shielded. engines (e.g. duplex filters) are to be provided with arrangements that will minimize the possibility of a 2.2.3 The high pressure fuel pipe and the outer filter under pressure being opened by mistake. Fil- jacket pipe have to be of permanent assembly. ters/filter chambers shall be provided with suitable means for: 2.2.4 Where pipe sheaths in the form of hoses are provided as shielding, the hoses must be demonstra- – venting when put into operation bly suitable for this purpose and approved by GL. – depressurizing before being opened 2.3 Fuel leak drainage Valves or cocks with drain pipes led to a safe location Appropriate design measures are to be introduced to shall be used for this purpose. ensure generally that leaking fuel is drained effi- ciently and cannot enter into the engine lube oil sys- tem. 4. Lubricating oil system 2.4 Heat tracing, thermal insulation, re-circulation 4.1 General requirements relating to lubricating oil systems and to the cleaning, cooling, etc. of the Fuel lines, including fuel injection lines, to engines lubricating oil are contained in the GL Rules for Ship which are operated with preheated fuel are to be Operation Installations and Auxiliary Systems (III-1- insulated against heat losses and, as far as necessary, 4), Section 8, I. For piping arrangement 2.1.5 is to be provided with heating. applied. Means of fuel circulation are also to be provided. 4.1.1 Engines which sumps serve as oil reservoirs 2.5 Filter oil emulsions shall be so equipped that the oil level can be estab- lished and, if necessary, topped up during operation. For engines operated on emulsions of fuel oil and Means shall be provided for completely draining the other liquids it has to be ensured that engine opera- oil sump. tion can be resumed after failures to the fuel oil treatment system. 4.1.2 The combination of the oil drainage lines from the crankcases of two or more engines is not 3. Filter arrangements for fuel oil and lubri- allowed. cating oil systems

3.1 The requirements for the fuel and lubricating 4.1.3 The outlet ends of the drain lines from the oil filter equipment of motors are defined in the GL engine sump shall be below the oil level in the drain Rules for Ship Operation Installations and Auxiliary tank. Systems (III-1-4), Section 8. 4.2 The equipment of engines fitted with lubri- 3.2 Fuel and lubricating oil filters which are to cating oil pumps is subject to the GL Rules for Ship be mounted directly on the engine are not to be lo- Operation Installations and Auxiliary Systems (III-1- cated above rotating parts or in the immediate prox- 4), Section 8, I. imity of hot components. 4.2.1 Main lubricating oil pumps driven by the 3.3 Where the arrangement stated in 3.2 is not engine are to be designed to maintain the supply of feasible, the rotating parts and the hot components lubricating oil over the entire operating range. are to be sufficiently shielded.

3.4 Filters have to be so arranged that fluid resi- 4.2.2 Main engines which drive main lubricating dues can be collected by adequate means. The same oil pumps are to be equipped with independently applies to lubricating oil filters if oil can escape when driven stand-by pumps. the filter is opened. 4.2.3 In installations comprising more than one 3.5 Change-over filters with two or more cham- main engine and with separate lubricating oil systems bers are to be equipped with means enabling a safe approval may be given for the carriage on board of pressure release before opening and a proper venting reserve pumps ready for mounting provided that the before re-starting of any chamber. Normally, shut-off arrangement of the main lubricating oil pumps en- devices are to be used. It shall be clearly visible, ables the change to be made with the means available which chamber is in and which is out of operation. on board. Chapter 2 Section 3 H Internal Combustion Engines III - Part 1 Page 3–18 GL 2012

4.2.4 Lubricating oil systems for cylinder lubrica- 6.1.4 Even at low engine speeds, main engines tion which are necessary for the operation of the shall be supplied with charge air in a manner to en- engine and which are equipped with electronic dosing sure reliable operating. units have to be approved by GL. 6.1.5 If, in the lower speed range or when used for manoeuvring, an engine can be operated only with a 5. Cooling system charge air blower driven independently of the engine, a stand-by charge air blower is to be installed or an 5.1 For the equipment of engines with cooling equivalent device of approved design. water pumps and for the design of cooling water systems, see the GL Rules for Ship Operation Instal- 6.1.6 With main engines emergency operation is lations and Auxiliary Systems (III-1-4), Section 8, J. to be possible in the event of a turbocharger failure. and K. 6.2 Charge air cooling

5.1.1 Main cooling water pumps driven by the 6.2.1 The construction and testing of charge air engine are to be designed to maintain the supply of coolers are subject to the GL Rules for Ship Opera- cooling water over the entire operating range. tion Installations and Auxiliary Systems (III-1-4), Section 16. 5.1.2 Main engines which drive main cooling water pumps are to be equipped with independently 6.2.2 Means are to be provided for regulating the driven stand-by pumps or with means for connecting temperature of the charge air within the temperature the cooling water system to independently driven range specified by the engine manufacturer. stand-by pumps. 6.2.3 The charge air lines of engines with charge air coolers are to be provided with sufficient means 5.1.3 In multi-engine installations having separate of drainage. fresh cooling water systems approval may be given for the carriage on board of reserve pumps ready for mounting provided that the arrangement of the main 7. Exhaust gas lines fresh cooling water pumps enables the change to be made with the means available on board. Shut-off 7.1 Exhaust gas lines are to be insulated and/or valves shall be provided enabling the main pumps to cooled in such a way that the surface temperature be isolated from the fresh cooling water system. cannot exceed 220 °C at any point. 7.2 General rules relating to exhaust gas lines 5.2 If cooling air is drawn from the engine are contained in the GL Rules for Ship Operation room, the design of the cooling system is to be based Installations and Auxiliary Systems (III-1-4), Section on a room temperature of at least 45 °C. 8, M. The exhaust air of air-cooled engines may not cause any unacceptable heating of the spaces in which the 8. Starting equipment plant is installed. The exhaust air is normally to be The relevant equipment is defined in the GL Rules led to the open air through special ducts. for Ship Operation Installations and Auxiliary Sys- tems (III-1-4), Section 6. 5.3 Where engines are installed in spaces in which oil-firing equipment is operated, GL Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 17, A.6. is also to be complied with. H. Control Equipment

6. Charge air system 1. General For unmanned machinery installations, GL Rules for 6.1 Exhaust gas turbochargers Automation (III-1-3b) are to be observed in addition to the following requirements. 6.1.1 The construction and testing of exhaust gas turbochargers are subject to Section 4b. 2. Main engines

6.1.2 Exhaust gas turbochargers may exhibit no 2.1 Local control station critical speed ranges over the entire operating range To provide emergency operation of the propulsion of the engine. plant a local control station is to be installed from which the plant can be operated and monitored. 6.1.3 The lubricating oil supply shall also be en- sured during start-up and run-down of the exhaust gas 2.1.1 Indicators according to Table 3.7 are to be turbochargers. clearly sited on the local main engine control station. III - Part 1 Section 3 K Internal Combustion Engines Chapter 2 GL 2012 Page 3–19

2.1.2 Temperature indicators are to be provided on 1.3 The GL Rules for Automation (III-1-3b) are the local control station or directly on the engine. to be observed for the layout of alarm and safety systems. 2.1.3 In the case of gear and controllable pitch propeller systems, the local control indicators and 2. Scope of alarms control equipment required for emergency operation are to be installed at the main engines local control Alarms have to be provided for main, auxiliary and station. emergency engines according to Table 3.7.

2.1.4 Critical speed ranges are to be marked in red on the tachometers. J. Engine Alignment/Seating 2.2 Machinery control centre 1. Engines are to be mounted and secured to If the naval ship has a control station for the propul- their foundations in conformity with the GL sion system with remote operation or control, the Guidelines for the Seating of Propulsion Plants and control indicators listed in Table 3.7 are to be in- Auxiliary Machinery (VI-4-3). stalled in this centre. 2. The crankshaft alignment is to be checked 2.3 Bridge/navigation centre every time an engine has been aligned on its founda- tion by measurement of the crank web deflection 2.3.1 The essential operating parameters for the and/or other suitable means. propulsion system are to be provided in the control station area. For the purpose of subsequent alignments, note is to be taken of: 2.3.2 The following stand-alone control equip- – the draught/load condition of the ship ment is to be installed showing: – the condition of the engine - cold/preheated/hot – speed/direction of rotation of main engine 3. Where the engine manufacturer has not – speed/direction of rotation of shafting specified values for the permissible crank web deflec- tion, assessment is to be based on GL's reference – propeller pitch (controllable pitch propeller) values.

– starting air pressure 4. Reference values for crank web deflection can be found in the GL Rules for Machinery Installa- – control air pressure tions (I-1-2), Section 2, K. Another scope of control equipment may be agreed between Naval Administration, shipyard and GL. 2.3.3 In the case of engine installations up to a K. Exhaust Gas Cleaning Systems total output of 600 kW, simplifications can be agreed with GL. 1. General If naval ships shall be equipped with exhaust gas 3. Auxiliary engines cleaning systems these should comply with the appli- For auxiliary engines and emergency application cable statutory requirements like the MARPOL Con- engines the controls according to Table 3.7 are to be vention. In case of wet exhaust gas cleaning systems provided as a minimum. (scrubber systems) IMO Resolution MEPC.184(59) applies.

1.1 Application I. Alarms The following requirements apply to exhaust gas cleaning systems which reduce the amount of nitro- 1. General gen oxides (NOx), sulphur oxides (SOx) or particu- late matter from the exhaust gases of internal com- 1.1 The following requirements apply to ma- bustion engines, incinerators or auxiliary steam boil- chinery installations which have been designed for ers. conventional operation without any degree of auto- mation. 2. Approval 1.2 Within the context of these requirements the Where an exhaust gas cleaning system is installed word alarm is understood to mean the visual and details of the arrangement and a description of the audible warning of abnormal operating parameters. function are to be submitted to GL for approval. Chapter 2 Section 3 K Internal Combustion Engines III - Part 1 Page 3–20 GL 2012

Table 3.7 Alarms and indicators

Auxiliary Description Propulsion engines Emergency engines engines Speed/Direction of rotation I Engine overspeed 4 A, S A, S A, S Lubricating oil pressure at engine inlet I, L 8, S I, L 8, S I, L 8 Lubricating oil temperature at engine inlet I, H I 4, H 4 I 4, H 4 Fuel oil pressure at engine inlet I I Fuel oil leakage from high pressure pipes A A A Cooling cylinder water pressure at engine inlet I, L I 3, L 3 I 3, L 3 Cooling cylinder water temperature at engine I, H I, H I, H outlet Charge air pressure at cylinder inlet I Charge air temperature at charge air cooler inlet I Charge air temperature at charge air cooler outlet I, H Starting air pressure, if applicable I, L Control air pressure I, L Exhaust gas temperature 1 I, H 2 Oil mist concentration in crankcase or alternative I, H I, H I, H monitoring system 5, 6 , 7

1 where ever the dimensions permit, at each cylinder outlet and at turbocharger inlet and outlet 2 at turbocharger outlet only 3 cooling water pressure or flow I : Indicator 4 only for an engine output ≥ 200 kW A : Alarm 5 for engines having an output limit > 2250 kW or a cylinder bore 300 mm H : Alarm for upper limit 6 alternative methods of monitoring may be approved by GL L : Alarm for lower limit 7 an engine shut-down may be provided where necessary S : Shut-down 8 only for an engine output > 37 kW

2.1 Documents for approval served. Thermal expansion of the system and its mechanical connections to both the ship’s structure For approval, drawings showing the main dimensions and the exhaust pipes has to be considered. The re- of the systems shall be submitted including documen- quirements for exhaust gas lines set out in the GL tation concerning installation requirements and op- Rules for Ship Operation Installations and Auxiliary erational features. An operating manual shall include Systems (III-1-4), Section 8, M. shall be taken into instructions for emergency operation, if applicable. account. The aftertreatment system is to be equipped with at least one inspection port. 2.2 Approval Certificate Exhaust gas cleaning systems are to be accessible for After successful appraisal of the required documents inspection and maintenance. A change or removal of and successful conclusion of the shipboard test in internal components shall be possible, where applica- presence of a Surveyor GL issues an Approval Cer- ble. tificate. 3.2 Bypass 3. Layout Where an exhaust gas cleaning system is installed 3.1 System layout and installation with a single main propulsion engine a bypass, con- trolled by flap valves or other suitable cut-off de- Exhaust gas cleaning systems shall be independent vices, is required in order to allow unrestricted engine for each combustion engine or combustion plant. operation in case of system failure. The bypass shall General requirements on the use of combustible ma- be designed for the maximum exhaust gas mass flow terials and on structural fire protection are to be ob- at full engine load. III - Part 1 Section 3 K Internal Combustion Engines Chapter 2 GL 2012 Page 3–21

In case of an exhaust gas cleaning system installed on minimum, the following operating parameters shall an engine of a multi engine plant a bypass system be monitored: may be dispensed with. – gas temperature upstream of the exhaust gas cleaning system 3.3 Additional pressure loss – gas temperature downstream of the exhaust gas The total pressure loss in the exhaust gas system, cleaning system including the additional pressure loss from the ex- haust gas cleaning system, shall not exceed the – pressure drop across the exhaust gas cleaning maximum allowable exhaust gas back pressure as system specified by the engine manufacturer at any load – engine exhaust gas back pressure condition. – position of flap valves 3.4 Maximum gas pressure 4. Materials The maximum pressure in the system of the exhaust pipes as specified by the manufacturer shall not be All materials of the exhaust gas cleaning system, exceeded. Care is to be taken in particular where the connecting pipes and chemically reactive agent dos- exhaust gas cleaning system is located upstream of ing units shall be non-combustible. The requirements the turbocharger of the combustion engine. relating to exhaust gas lines as contained in the GL Rules for Ship Operation Installations and Auxiliary 3.5 Oscillation characteristics of the exhaust Systems (III-1-4), Section 8, M. are to be observed, gas column as applicable.

The installation and operation of the exhaust gas 5. Chemically reactive agents cleaning system shall not have an adverse effect on the oscillation characteristics of a combustion en- 5.1 Reducing agent gine’s exhaust gas column in order to avoid unsafe engine operation. For Selective Catalytic Reduction (SCR) type exhaust gas cleaning systems the reducing agent (Ammonia, 3.6 Deposition of soot dissolved Ammonia, Urea or the like) has to be stored and pumped in tanks and pipes made of approved The deposition of soot within or in the proximity of materials for these types of agents, see the GL Rules the exhaust gas cleaning system should be avoided. for Ship Operation Installations and Auxiliary Sys- Where this may lead to additional fire hazards the tems (III-1-4), Section 8, M. deposition of soot is not acceptable. 5.2 Ammonia slip 3.7 Vibrations in piping system Where Selective Catalytic Reduction (SCR) type The design and installation of the exhaust gas clean- exhaust gas cleaning systems are applied, excessive ing system including the exhaust gas piping system slip of ammonia has to be prevented. shall account for vibrations induced by the ship’s machinery, the pulsation of the exhaust gas or vibra- 5.3 Washwater criteria tions transmitted through the ship’s structure in order to prevent mechanical damage to the piping system. Where the exhaust gases are washed with water, Consideration should be given to the installation of discharged wash water has to comply with criteria as damping systems and/or compensators. specified in IMO Resolution MEPC.184(59).

3.8 Monitoring of the operating parameters 6. Shipboard testing The main operating parameters of the exhaust gas The exhaust gas cleaning and bypass system is sub- cleaning system have to be monitored and should ject to inspection and functional tests in each case in serve as indicators for possible abnormalities. As a the presence of a Surveyor.

III - Part 1 Section 4a A Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–1

Section 4a

Thermal Turbomachinery/Gas Turbines

A. General submitted, so far project related and therefore not covered up by the type approval (see 3.3 and 3.4). 1. Application Responsible for submission of the installation draw- ings on the ship is the contractual partner of GL dur- 1.1 Gas turbines on naval ships for the applica- ing the building phase. tions – essential main propulsion 2. Definitions – non-essential propulsion The following definitions are to be applied: – driving of auxiliaries 2.1 Essential main propulsion as defined in 2. are subject to these Rules. According to the special purpose of the type of naval ship, they The gas turbine serves as exclusive drive for the are to be designed, constructed, tested, certified and propulsion elements and is essential for the safety and installed on board in accordance with the require- manoeuvrability of the ship. ments of this Section.

1.2 Gas turbines installed on GL classed ships 2.2 Non-essential propulsion and not fulfilling purposes as described under 1.1 are not subjected to the rules of this Section. They have Other propulsion drives, e.g. internal combustion nevertheless to fulfil all requirements related to pas- engines or other gas turbines, secure the safety and sive safety (fire protection, containment, safety de- manoeuvrability of the ship and the gas turbine in vices for rendering to a safe state after malfunction or question is only temporarily used as booster to failure of components). achieve maximum ahead speed.

1.3 Gas turbines with a power less than 500 kW 2.3 Driving of auxiliaries are not required to comply with the rules of this Sec- tion, but have to be designed, constructed and The gas turbine is not directly involved in the propul- equipped in accordance to good practice for marine sion of the ship, but drives a generator or other auxil- applications. iary units of the machinery systems.

1.4 Acceptance is based on test bed results for a 2.4 Maximum permissible power (type re- prototype (manufacturer´s documentation) and suc- lated) cessful performance test after installation in presence of a surveyor. Further documentation may be re- The maximum permissible power is the maximum quested for appraisal purposes upon agreement be- power of the applied type of gas turbine in the actual tween GL, manufacturer and shipyard. upgrade version, independent of project dedicated application. This is the base for design calculations 1.5 Subject to approval is the complete gas tur- and type approval procedure. bine plant including foundation, piping, fuel, lubrica- tion, cooling as well as safety, control, monitoring and alarm systems. The rules of this Section, espe- 2.5 Maximum continuous rating (project cially for plants as described under 1.1, apply for the related) gas turbine unit itself, as well as for the complete installation. Typically the gas turbine unit with mani- Maximum continuous rating means 100 % gas tur- fold integrated feeding systems, internal clutches, bine power (MCR condition). The gas turbine is to be combustion chambers, etc. is subject to type ap- limited to the specified maximum continuous rating proval, the installation, connection and foundation of after performance test in the manufacturer’s facilities the complete manifold on the ship´s side are project and/or onboard after installation. specific. This rating is the relevant power for dimensioning of So far the gas turbine type/version has been subjected the driven devices, such as gear box, shaftings, etc. to a type approval, the relevant drawings are to be for a specific application. Chapter 2 Section 4a A Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–2 GL 2012

3. Documents for approval menclature (Schematic indication of gas turbine unit with all connections to the feeding / con- 3.1 General trolling systems) Design drawings of gas turbines are to be submitted – arrangement within engine room with fire and to GL for approval. The drawings shall contain all the safety details (location of doors, fans, fire details necessary to carry out an examination in ac- dampers, materials and insulation, location of cordance with the following requirements. To facili- electrical and control panels) tate a smooth and efficient approval process they 1 – documentation of starting system with ar- should be submitted electronically via GLOBE . In rangement drawings, capacity data, a proof of specific cases and following prior agreement with GL capability to perform the required start at- they can also be submitted in paper form in triplicate. tempts, starting logic and set points 3.2 Gas turbine unit (manifold) – drawings of the fuel system including piping, instrumentation diagrams, purification and fil- The following drawings are to be supplied by the gas tering equipment, specification of fuel as re- turbine manufacturer within the type approval proce- quired by the turbine manufacturer dure: – specification of the fuel metering valve includ- – general arrangement drawing of complete ing material specification, flow rates, control manifold with manufacturer´s term definitions parameter and instrumentation, calibrating – assembly and sectional drawings process – rotor assembly drawings including general – shielding of fuel oil system piping dimensions and materials – lubrication system in form of schematic piping – detailed drawings of rotating parts (turbine and diagrams, including pumps, valves, tanks, indi- compressor, discs, shaftings, blades for gas cators, filtering equipment, etc. generator and power turbine, including dimen- – drawings shall indicate maximum and mini- sions, materials and treatment (coating, heat mum pressure and temperature in the system treatment, etc.) (idling and MCR values) – casings – type of recommended lubricating oil and ap- – containment calculations for the failure mode proved list of lubricants "blade loss", so far available. This may be re- – maximum permissible amount of water in the placed by documented experimental data for a oil prototype of the gas turbine. Instead also ex- perimental verification of integrity at higher – control oil system speeds than 115 % * nrated may be accepted (for – air-intake and exhaust gas system (including existing and proven designs). filtration and silencer system) – bearings, thrust bearing arrangement – bleed / cooling / seal air system – sealing system – heat balance and design of the cooling air sys- – combustion chambers including burners with tem to be documented on a separate drawing dimensions and materials indicating the maximal/minimal flow rates, the corresponding pressures of cooling air and de- – foundation and fastening (frames) sign temperatures at rated power / speed of the – material specifications including their mechani- power turbine. cal and chemical properties for the rotating – water wash system – blade cleaning system parts, combustor and casing. – appended manifolds including gears, clutches, 3.3 Gas turbine systems (partly manifold couplings integrated, partly project specific) – fire protection system. Complete documenta- The majority of the following documents are to be tion of fire safety procedures e.g. type and ca- adapted to the needs of the specific project and may pacity of fire extinguishing medium, location be not part of the type approval hold by the gas tur- and specification of fire (flame) detection, bine manufacturer. specification of control system action se- quences – general arrangement drawing of complete sys- tem with block indication and technical no- – foundation and fastening (frames to the ship´s structures, resilient mountings if applicable) –––––––––––––– – electrical installations, instrumentation, alarms, 1 Detailed information about GLOBE submission can be found safety system on GL’s website www.gl-group.com/globe. III - Part 1 Section 4a C Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–3

– governor arrangement/system 5. Certification – Failure Mode and Effect Analysis (FMEA) for If the requirements of this Section are met and the the control system (extent to be agreed upon type tests defined in F.2.3 were carried out success- individually between manufacturer and GL) fully, a Type Approval Certificate will be issued. For further gas turbines of the same type and applications 3.4 Design data for a specific project mentioned under A.1. work’s tests (FAT) as defined in F.2.4 shall be carried out and a Certificate will be For each specific project related application of gas issued. turbines the following basic design data has to be specified: – maximum continuous power, corresponding speed for gas generator and power turbine (pro- B. Materials ject related) – maximum permissible rates (limitation for 1. Gas turbine materials have to fulfil the re- project, but in any case lower than maximum quirements specified by the operating conditions for permissible power as per type approval) the individual engine component. In the choice of materials the effects of creep, thermal fatigue, oxida- – rated power turbine inlet temperature (and tion and corrosion, to which the different components limit) of the gas turbine unit are exposed, have to be con- sidered. – rated compressor discharge temperature (and limit) permissible (tolerable) combustor outlet 2. For materials the information about suitabil- temperature deviation ity of mechanical properties such as chemical compo- – maximum intake air temperature at which rated sition, yield strength, elongation, fatigue properties as power can be achieved (to be not less than well as the applied heat treatment is required. Where 15 °C) composite material is used, their manufacturing pro- cedures are to be specified. – balancing data sheet (minimum requirements) For the turbine blades only corrosion and heat- – scheme with moment of inertias and stiffnesses, resistant materials are to be applied. so far applicable, of rotating parts – schedule and description of the intended per- 3. The production procedures including weld- formance test (FAT = Factory Acceptance ing are to be qualified according to a recognised Test) with list of parameters to be registered standard or the relevant Rules of GL. and documented. 4. For welding seams full details as filler metal 3.5 Maintenance particulars, heat treatment after welding and NDT for A plan is to be submitted to GL specifying the time high stress seams are required and welding procedure intervals and extent of works for planned mainte- specifications shall be included in the submitted, nance. relevant drawings. In case of Continuous Machinery Survey agreement 5. For the air pipes steel or another equivalent the maintenance scheme shall be adapted accord- material has to be used. Flexible connections / hoses ingly. have to be non-flammable.

4. References to further Rules 6. As material for exhaust gas pipes heat- resistant steel has to be used. The choice of the steel 4.1 GL Rules type has to consider the operation temperatures and the corrosion resistance, see also DIN 86009. The latest issue of the following GL Rules have to be observed: 7. Pipes and fittings are to be manufactured – Materials and Welding (II) from stainless steel.

4.2 Other rules and regulations

– DIN ISO 1940: Mechanical vibration – Balance C. Design and Construction quality requirements for rotors in a constant (rigid) state 1. General – ISO 2314: Gas turbines – Acceptance tests The gas turbine design shall be suitable for marine – DIN 86009: Exhaust gas lines on ships; steel application and enable the full manoeuvrability of the tubes ship. Chapter 2 Section 4a C Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–4 GL 2012

Gas turbines shall be designed to permit fast start-up Regarding burners the following parameters are to be from cold conditions. Further possibilities are to be observed: provided enabling manual re-start despite control system constraints after acknowledgement of the – maximum/minimum temperature and supply cause of tripping or start failure. pressure of fuel Gas turbines shall be designed for minimum times – maximum mass flow rate of the fuel and the between overhauls (TBO) of > 1000 running hours. expected air flow (fuel/air ratio) So far classified as unique main propulsion unit, the The burner lifetime shall be specified as well as the gas turbine is expected to operate without major recommended replacement / maintenance intervals. interruptions. The machinery class intervals, if rele- vant, shall be adapted in such case to the required 5.2 The combustor shall have a dual ignition planned maintenance scheme of the propulsion sys- system. During operation the igniters shall not be tem. exposed to the high temperatures of the primary combustion zone. 2. Blades A blade strength calculation for the maximum per- 5.3 Optical and/or thermal flame sensors shall missible output/speed shall be submitted by means of enable inspection of the flame during operation. finite element analysis (FEM) or other sound engi- neering methods for review. The following loads 6. Adjustable vanes shall be taken into account: centrifugal and axial forces, gas pressure as well as thermal loads. The 6.1 So far the compressor air flow is controlled calculations may contain the design equivalent full by means of variable guide vanes (VGV), inlet guide load operation hours or (if applicable) the assumed vanes (IGV) or/ and variable stator vanes (VSV) the load profile. corresponding mass flow charts over the guide vane Cleaning equipment is to be provided during gas angle / travel have to be indicated in the form of a turbine operation for removal of blade deposits from chart or table. compressor and turbine. 6.2 The actuator is to be designed in a way to be capable to operate the adjusting mechanism of the 3. Rotor Assembly vanes under all conditions. Corresponding charts / tables shall be available on request. Each shaft as well as the complete rotating assembly of compressor and turbine has to be individually dynamically balanced in accordance with the ap- 7. Internal air cooling system proved quality control procedure. The balancing The design shall be such to enable an adequate air specification and the results of the balancing proce- flow capacity to keep the temperature in the power dure are subject of the documentation in accordance turbine safely within the design limits under full load to A.3.4. The requirements as set out in DIN ISO conditions. 1940 apply, specifically class G2.5 or equivalent standards. 8. Bleed valves 4. Casing 8.1 The arrangement of bleed valves shall be documented in a drawing, indicating their position 4.1 A blade or impeller loss may not result in and size. The associated (maximal) power loss of the casing penetration and consequential loss of other turbine shall be specified for the maximal flow rates components, injury or other hazardous conditions for of the bleed valves. the ship. Casing integrity has to be maintained in case of blade 8.2 In case that bleed air is used for anti-icing loss at the most critical speed but not higher than purposes, this system and its associated technical 115 % of the rated speed, which is to be demon- parameters such as flow rate, supply pressure, maxi- strated by containment calculations or other methods. mum air temperature and simplified heat balance, shall be submitted for information purposes. 4.2 The casing shall have sufficient openings to enable boroscope inspection of the combustor as well 9. Bearings as for the compressor´s and turbine´s individual stages. 9.1 Bearings are generally to be designed in accordance to the manufacturer's standards for loads 5. Burners and combustors resulting from the turbine's full output operation for an adequate life time (compare 1.). They are to be 5.1 Fuel nozzles are to be removable without equipped with adequate, replaceable sealing devices disassembly of the combustor system. and shall be reliably lubricated to withstand also short III - Part 1 Section 4a C Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–5

time operation under normal or exceptional transient 11.4 Purging of all internal gas turbine parts is conditions, such as shut-down due to trip, blackout, required in order to discharge liquid or gaseous fuel etc. before ignition. Purging shall be automatically initi- ated for an adequate time before ignition signal is 9.2 Vibration monitoring for the bearing condi- released. tion may be required by GL, depending on the appli- cation. 11.5 Where surface temperatures exceed 220 °C, insulation of oil non-absorbent material has to be applied. In case that the insulation material may be 10. Gas turbine enclosure penetrated by fuel, it is to be additionally shielded by 10.1 The enclosure shall include a system for fire sheet steel or equivalent. detection and automatic fire extinguishing. 12. Starting systems 10.2 The enclosure ventilation or cooling air of the gas turbine shall be supplied from redundant fans 12.1 The starting system, electrically, pneumati- with separated electrical power supply. cally or hydraulically driven, shall have redundancy regarding technical design and physical arrangement. The distribution of ventilation air shall ensure that an A redundancy of starting system is not required if acceptable temperature profile of the gas turbine is redundant propulsion gas turbines are available each maintained, and that any local accumulation of com- one with its own starting systems. The same applies bustible gas mixtures is prohibited. for turbines installed in plants in combination with In case of emergency, closing of the ventilation ducts other power units for back up, such as diesel engines of the plant shall be feasable in a controlled way and or electric motors. within short time, avoiding further damages due to 12.2 The capacity of the starting system is to be local overheating. designed in order to enable six (6) consecutive starts 10.3 The enclosure shall be equipped with at least of gas turbines for essential main propulsion duties two exits, arranged on opposite sides of the enclo- (controllable pitch propellers or other device enabling sure. The exits shall provide an easy escape from all the start without opposite torque) respectively three relevant positions inside the enclosure. (3) consecutive starts of gas turbines for non-essential propulsion and driving of auxiliaries. The recovery Interlocks on doors shall be provided to ensure that time of the starting system depends on minimum time fire extinguishing medium hazardous to personnel is available between start attempts based on starting and not released, when personnel are inside the enclosure. control cycles.

A gas turbine start is to be interlocked when person- 12.3 Prior to ignition process, automatic purging nel are inside the enclosure and the enclosure doors is required for all starts and restarts. The purge phase are open. During operation the doors have to be is to be of sufficient duration in order to remove all locked. the accumulated fuel.

10.4 If NBC protection of the machinery rooms is 12.4 The starting control system is to be fitted required the air pressure in the enclosure should be with ignition detection devices. If light-off will not be kept lower by not less than 0,5 hPa (0,5 mbar) than achieved within a preset time, the control system has the pressure in the machinery room. to abort the ignition automatically, shut-off the main fuel valve and release a purge cycle. 11. Fire safety 12.5 The start system shall have its own protec- 11.1 In addition to the machinery room fire fight- tive system to ensure prevention of damage due to ing system, an approved automatic fire extinguishing overspeed or failure to reach ignition speed. system is to be provided for each gas turbine enclo- sure. The starting system is to be protected prior to me- chanical and electrical overload. Enclosure ventilation ducts are to be automatically closed when a confirmed fire is detected. 13. Lubricating oil system 11.2 Inside of enclosure four flame detectors shall be arranged at different locations. A type approval is 13.1 For multiple gas turbine arrangements each required for flame detectors. turbine shall be supplied by a separate and independ- ent lubrication oil system. Detected fire in enclosure or engine room has to release an alarm and automatic cut off of the fuel 13.2 Bearing lubrication may not be impaired by supply. hot gases or by adjacent hot components.

11.3 The accumulation of flammable fluid inside 13.3 The lubricating oil system has to be of enclosure bottom has to be prevented by draining. equipped with sufficient means for filtering, heat Chapter 2 Section 4a D Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–6 GL 2012

exchange, magnetic chip detection and water separa- 16. Emergency operation tion in accordance to usual marine practice. 16.1 In multi-shaft installations, further operation The lubrication equipment of a gas turbine is to be of at least one propulsion train has to be feasible in arranged and protected in a way, that in case of leak- the case that one train is unavailable. age the lubricating oil will not be spoiled over sur- faces with a temperature of above 220 °C and will not reach any rotating parts. 16.2 In single-shaft installations with two or more essential main gas turbine driving units, care is to be The lubricating oil system has to be equipped with a taken to enable further propulsion on a reduced filter device, for which cleaning is possible without power level , in the event of failure or unavailability interruption of operation of the turbine. For redundant of one of the gas turbines. Each gas turbine is to be plants and other applications as described under 12.1 designed in a way to be able to drive the shaft on a double filters are not required. The condition of the reduced power level, still enabling at least secure filter (s) is to be monitored by indication of the pres- manoeuvring of the ship. sure difference or other adequate means. Tanks are to be equipped with oil stand indications combined with 16.3 In the case of single-shaft installations with a low level alarm. Re-filling of oil shall be possible only one essential main gas turbine, special provi- without interrupting the operation. Means for taking sions are to be met in agreement with GL to ensure of representative samples for analysis purposes are to additional adequate redundancy on the level of com- be provided. ponents / systems.

13.4 Especially in case of application of synthetic lubricants attention shall be given to the compatibility to the materials of sealing arrangements and heat D. Control and Monitoring exchangers. Leakages within heat exchangers should not lead rapidly to a total contamination of the lubri- 1. Control logic cation oil. 1.1 Gas turbines are to be installed with a type 14. Fuel oil systems approved control and monitoring system. Gaseous fuel or combined gas / liquid fuel is ex- cluded for the scope of these Rules. 1.2 The control logic shall include the follow- ing: 14.1 Fuel nozzles are to be replaceable as com- – monitoring of relevant operational parameters plete units without requirement of major adjustments for control purposes, such as vibration, tem- works after replacement. perature, speed, etc. including limits and set points 14.2 The system is to be equipped with suitable – normal and emergency stop and start sequence drain facilities for the fuel manifold and fuel nozzle to safely handle excessive fuel originating from shut- – load control down (normal and emergency) of the engine fuel – fuel control for normal running system. – fuel control for shut-down 14.3 The combustors are to be equipped with a – alarms and shut-down separate drainage system, preventing accumulation of fuel after a failed start. – automatic purge cycle – other systems (auxiliary supply systems and 14.4 The day tank for the fuel supply of the gas safety systems) turbine shall have adequate capacity referenced to the ship´s destination and the purpose of installation of a – override functions gas turbine for essential main propulsion. The day 1.3 A Failure Mode and Effect Analysis tank has to contain fuel in accordance to the specifi- (FMEA) is required for the verification of the logical cations of the gas turbine maker adequately condi- interconnections within the control system of gas tioned for immediate use. turbines for essential main propulsion. Single failure of any system or control during operation at any 15. Turning gear mode shall not lead to loss of control of safety related Essential main propulsion turbines are to be equipped properties of the ship, e.g. loss of control of propul- with turning gear both for the gas generator as well as sion, manoeuvrability for propulsion units, loss of for the power turbine. electrical supply for auxiliary turbines, etc. Safe op- eration of the ship is to be demonstrated within the The rotors of turbines for driving of auxiliaries shall FMEA after partly or complete failure or malfunction at least be capable of being turned by hand. of a gas turbine unit, subjected to these rules. III - Part 1 Section 4a D Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–7

2. Operation characteristics 2.4 The safety system has to work independently from the gas turbine control. In the case of activation 2.1 Automation of a safety device, the gas turbine has to be blocked against a new start, before manual acknowledgement. Automation shall be used to simplify operation and The devices for de-blocking have to be arranged in a control and exclude operational mistakes by an auto- way enabling a quick re-start attempt of the gas tur- matic initiation of procedures operationally con- bine. nected to each other. In addition automation shall enable a centralised handling and control of the pro- 3. Control stations pulsion plant. The equipment for local manual hand- ling and control has to exist to a full extent independ- 3.1 The operation of the gas turbine shall be ently from the degree of automation. possible by remote control from the machinery con- The procedures to prepare the ship for sea shall not trol centre (MCC). The wiring for control purposes be included in the automation. shall be independent and free of cross-connections to other systems. 2.2 Starting 3.2 An additional manual control is to be pro- Start-up shall take place automatically in a defined vided directly at the gas turbine´s enclosure and shall sequence. Interlocks are to be provided to ensure that include a shut-down release. This shall interrupt the this sequence (attainment of ignition speed, ignition, fuel supply instantaneously. flame monitoring) is followed. Suitable operating devices have to be provided at a Starting sequence is to be disconnected and main fuel good accessible position. valve to be closed within a pre-determined time, when ignition has failed. 3.3 The operation of the gas turbine control system shall be independent of the common ship The purging mode is to be integrated in the control control system. system both for normal start-up as well as after start failure. The duration of required purging should nor- 4. Power supply mally be sufficient to displace the exhaust system volume three times before attempting re-start. The control system is to be equipped with an uninter- ruptible power supply designed to maintain supply 2.3 Speed control also under blackout conditions. Total loss of control system power shall lead to a controlled and safe tur- 2.3.1 Gas turbines within the scope of these Rules bine shutdown. are to be fitted with a speed governor which, in the event of a sudden load drop, prevents the revolutions 5. Monitoring from increasing to the trip speed. An instrumentation list showing sensor, type, set point and measuring limit for essential main propul- 2.3.2 The speed increase of gas turbines driving sion gas turbines is required according to Table 4a.1 electric generators subsequent to a load drop from for approval. 100 % to idling may not exceed 10 % of the nominal speed and shall return to the steady state with a 6. Further requirements maximal deviation of 5 % of the nominal value within 2 s. The transient increase shall in any case For all equipment of control, operating and watch remain safely within the overspeed margin. stands and centres the requirements of the GL Rules for Automation (III-1-3b), especially Section 1 have 2.3.3 Gas turbine control systems are to be pro- to be applied. If an extended scope of the operating vided with overspeed protection preventing the tur- and control equipment is required by the Naval Ad- bine speed from exceeding 115 % of the maximum ministration, it has to be defined in the building continuous speed (project related speed). specification. Chapter 2 Section 4a D Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–8 GL 2012

Table 4a.1 Alarms and indicators for essential main propulsion gas turbines

Signal F = Fault Individual Group L = Low limit Alarm Alarm Shut-down H = High limit Indication Indication S = Shut-down Fuel temperature H Fuel oil supply pressure L Fuel filter, differential pressure 2 H Level in lubrication oil sump L H Lubrication oil pressure L L S Lubrication oil temperature inlet H Lubrication oil filter, differential pressure H Cooling water temperature H Cooling water pressure L Compressor inlet pressure H S H L or air intake filter, differential pressure L S Anti-icing system failure F Power turbine overspeed, speed sensor H H S Failure to reach idle speed 2 F Failure to ignite F F S Flame out detection F F S Power turbine inlet temperature 1 L Exhaust temperature (power turbine outlet) H H S Bearing temperature H Thrust bearing temperature H Vibration, vibration sensor (for each bearing) 3 H H S Axial displacement of power turbine, H H S thrust bearing value Power loss of monitoring system F Power loss of control system F Loss of cooling air supply (pressure or flow) L Starting system failure F Fire detection inside gas turbine enclosure F F S

1 Not less than 6 temperature sensors per turbine 2 Not required for generator driving turbines 3 details in accordance with monitoring concept of the gas turbine manufacturer

For non-essential propulsion gas turbines and gas turbines driving auxiliaries the extent of alarms and indicators has to be agreed upon with GL considering the save operation of these units. III - Part 1 Section 4a F Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–9

E. Arrangement and Installation 2. Air inlet and exhaust gas outlet system

1. Alignment and mounting 2.1 The air inlet shall be equipped with air filters in order to avoid the ingestion of dirt or harmful particles including sea salt deposits to the gas turbine. 1.1 Shaft alignment calculations of the complete The pressure drop across air filter shall be monitored drive train are to be submitted for approval. Both hot and indicated in relation to the maximal permissible and cold conditions are to be included in the calcula- value. tion. The shaft alignment calculation for propulsion purposes as required by GL is limited to the part Air filter icing is to be prevented by an anti-icing between gear box and propeller. The internal align- system, so far required by the specific application. ment of the turbine is to be carried out in accordance The suction of air intakes is to be arranged and de- to the manufacturer´s recommendations. signed in a way to limit intrusion of spraying water to a minimum. The air inlet shall be equipped with 1.2 In general the gas turbine foundation in means to enable drainage of water. combination with the resilient mountings and the frames shall be designed in a way, that ship deflec- 2.2 Air intakes and exhaust outlet are to be ar- tions do not cause distortions within the integral gas ranged in a way that re-ingestion of exhaust gases is turbine manifold. Design inherent deflections be- minimised. tween gas turbine unit and gear box are to be com- 2.3 Multi engine installations shall be equipped pensated by a suitable flexible element, such as elas- with separate inlets and outlets for each gas turbine. tic, tooth, reinforced plastic membrane, steel plate coupling, etc. 2.4 Inlet and exhaust silencers are to be fitted, if needed, in order to limit the sound power level. The 1.3 Further calculations, which may also be maximal sound power at a distance of one meter from required for naval ships, are not subject to the basic the gas turbine system shall not exceed 110 dB for classification procedure. Such calculations are: unmanned machinery spaces (typically in the gas – extreme loads due to given profiles of accelera- turbine's enclosure) or 80 dB for manned machinery tions control centres (MCC). – forces transferred to foundation structure due to 3. Vibration analysis deflection of the ship structure 3.1 For propulsion systems driving a propeller – application of specific external acceleration or water jet a torsional vibration of the complete loads transferred via the foundation to the tur- system including gas turbine and propulsion train is bine to be submitted for approval. As main excitation for – crash stop loads the system the periodical forces of the propeller / impeller may be regarded (1st and 2nd blade excita- – forces caused from blade loss due to blade tion). fracture – any other operational load significant for the 3.2 Excitations generated by the power turbine individual application may be neglected, unless specifically given by the manufacturer. Excitations exceeding 100 Hz can be Such calculations may be reviewed or carried out by neglected for the scope of torsional vibration calcula- GL on special request and in accordance with given tions. specifications. 3.3 Further vibration analyses such as bending vibrations may be required by the manufacturer of the 1.4 The gas turbine (power part) shall be con- gas turbine. The recommendations of the manufac- nected to any consumers, propulsion train or gear box turer in this respect shall be applied. by flexible couplings fulfilling also safety functions. Additional separating devices (clutches) are to be provided when more than one gas turbine is driving a common gear box or no controllable pitch propeller is F. Tests and Trials installed. 1. Material tests 1.5 Applied resilient mountings, elastic or other compensating couplings and clutches shall be pref- 1.1 Material certificates for the components as erably type approved. Due to the specific require- listed in Table 4a.2 are to be supplied on request. ments for the connecting components of turbine units Special agreements related to the manufacturing (high revolutions, major displacements) a case by procedures and suppliers have to be met on a case by case dedicated design/approval taking into account case base. The extent of tests shall at least comply the recommendations of the manufacturer shall be with the approved quality scheme of the manufac- considered. turer. Chapter 2 Section 4a F Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–10 GL 2012

Table 4a.2 Type of Material Certificate required for essential components

Component: Material Certificate 1 Blades Impellers Shafts Disks Tie bolts GL Material Certificate or Manufacturer Inspection Certificate to be decided case by case by GL dependent on the installed quality assurance Combustors system of the manufacturer Fuel nozzles Gas generator casing Turbine generator casing Labyrinth seals Manufacturer Inspection Certificate Bearings, hydrodynamic

1 Test Certificates issued according to the GL Rules for Principles and Test Procedures (II-1-1), Section 1, H.

1.2 Non-destructive examination 2.1.2 Rotor balancing Before final installation all completed rotors including Non-destructive examination shall be applied for the mounted discs shall be dynamically balanced. The rotors, blades, disks and welded joints of rotating balance procedure as well as the results before and parts. An other production control process may be after balancing shall be documented. For assessment accepted as equivalent for welded joints. The exami- DIN ISO 1940 or comparable regulations may be nation shall be performed by the manufacturer and the used. results together with details of the test method are to be evaluated according to recognised criteria of ac- 2.1.3 Cold overspeed test ceptability and documented in an acceptance protocol. Turbine and compressor wheels are to be tested at a speed at least 15 % above the rated speed for not less 2. Tests during construction at the manufac- than three minutes. turer’s works GL may accept mathematical proof of the stresses in the rotating parts at overspeed as a substitute for the 2.1 Tests on components overspeed test itself provided that the design is such that reliable calculations are possible and the rotating parts have been subjected to thorough non-destructive The following component tests have to be performed testing to ascertain their freedom from defects. for every gas turbine: 2.2 General requirements for testing of gas 2.1.1 Pressure and tightness test turbines

Turbine casings are to be tested with 1,5 times the 2.2.1 The planned procedures for the type test, design pressure. Design pressure is the highest ex- work's test as well as sea trials of complete gas turbine pected pressure within the casing under nominal oper- units are to be submitted for approval. The tests shall ating conditions (at least 1,25 times maximum allow- be be witnessed by a GL Surveyor. able working pressure under nominal conditions). 2.2.2 Type test is referring to one specific type of engine (new or upgraded design) and does not cover a The tightness test of the turbine casing may be re- range of substantial design variations. The maximum placed, so far not practicable, by other alternative speed of compressor and power turbine, firing tem- means with the agreement of GL. perature, turbine inlet temperature, exhaust tempera- ture, mass flow rates and power are typically fixed Further pressure vessels, such as coolers, heat ex- design values for a type of turbine. Such a list of char- changers, etc. are to undergo a pressure test with 1,5 acteristic parameters will be listed for reference pur- times of their design pressure. poses in the type approval Certificate. III - Part 1 Section 4a F Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–11

2.2.3 Every gas turbine, besides the extensively manufacturer, and attended by another independent type tested prototype, shall undergo, before delivery body or recognized Classification Society may be the work’s tests (Factory Acceptance Test) according accepted by GL after thorough review of the docu- to 2.4 and the sea trials according to 4., witnessed by a mentation. GL Surveyor and documented accordingly. 2.3.2 Scope of tests 2.2.4 Besides the characteristic gas turbine parame- The type test has to include: ters as listed in A.3., additionally the following pa- rameters indicating performance and consumption – start test under deviating ambient condition parameters shall be recorded: – emergency shutdown test – ambient air temperature – performance test – ambient air pressure – emergency operation test – relative humidity The test procedure is to be approved by GL prior test- ing. – lower heating value for liquid or gaseous fuel The following tests shall be carried out preferably – torque measured by absorption dynamometer or with the actual control system installed and fully ac- shaft torque meter tive. It is recommended to check the control system provisionally during type test and work´s test, but The measured ambient parameters as listed above additionally in combination with the finally installed shall be used in combination with the reference condi- system on the ship before or during the sea trials. tions as listed in Table 4a.3 for calculation of refer- enced values for specific fuel consumption, so far 2.3.3 Start test required by the Naval Administration. There has to be at least one false engine start simula- Table 4a.3 Standard reference conditions accord- tion, followed by the manufacturer’s specified mini- ing to ISO 2314 mum fuel drainage time before attempting a normal start. Temperature: 15 °C Three normal restarts after an emergency shutdown are to be performed. Humidity: 60 % relative 2.3.4 Emergency shut-down down test Barometric Pressure: 1013 mbar Emergency shutdown may be caused by: 2.2.5 The monitoring and control system used – hot shut-down, at full load; restart is to be during FAT (manufacturer test bed facilities) of the achieved before lockout and within 30 minutes. gas turbine manifold has to deliver equivalent and comparable parameter lists to the system´s, which will – failure to ignite, resulting in aborted start se- be applied on the ship or during containerization of the quence manifold. Latter systems are to be approved by the – flame out manufacturer of the gas turbine and have to be type approved by GL. During this test the gas turbine is to accelerate to the overspeed limit (115 %) in order to verify the function 2.2.6 After running on the test bed, the fuel deliv- of the overspeed shut-down. ery system of gas turbines for propulsion is normally to be adjusted and limited to 100 % power. The fuel 2.3.5 Performance test (type test) system for gas turbines driving generators may be 2.3.5.1 Test sequence limited to a higher value, but not higher than 110 % output. power. The limit value shall not exceed the The test sequence is as follows: "maximum permissible power" as defined under A.2. – 100 hours total at different part loads and time increments between maximum continuous tur- 2.3 Testing within type test procedure (FAT bine rotational speed and minimum idle speed Prototype) for propulsion applications (Propeller curve) or synchronous speed and different loads for gen- 2.3.1 General erator applications (Load Variation). For details Type approval of gas turbines includes an extended see 2.3.5.2 and 2.3.5.3 . type test for the first gas turbine of a family. The type – thereof at least 1 hour total at rated maximum test is to be carried out at the manufacturer’s facilities continuous power (100 % output at 100 % and is normally to be attended by a GL Surveyor. For torque and 100 % speed). already existing and proven design a well documented and complete type test procedure performed by the – 30 min. with 110 % power. Chapter 2 Section 4a F Thermal Turbomachinery/Gas Turbines III - Part 1 Page 4a–12 GL 2012

The performance test as roughly described herein and 2.4 Testing within work’s test procedure (FAT in 2.4 represents minimal requirements. It is taken for individual gas turbine) granted that the manufacturer has performed long term running trials for the first engine, which are docu- 2.4.1 General mented and available on request. Every gas turbine of a type approved type, subject to certification in accordance to A.5., shall undergo a In case that the gas turbine shall be offered for both propulsion and generator purposes, the performance work´s test in the facilities of the manufacturer before certification and delivery for installation. test shall include both load variation at variable speed (propeller curve) as well as constant speed. The type The work’s test procedure is to be approved by GL approval then covers up both applications, so far suc- prior testing. cessfully contacted. 2.4.2 Scope of tests 2.3.5.2 Propulsion plants The work’s test has to include: The performance test takes mainly reference to the – start test according to 2.3.3 100 % and 110 % output. Further investigation points – emergency shut-down test according to 2.3.4 under steady conditions shall be required in accor- dance to the available facilities. Commonly the 90 %, – performance work’s test according to 2.4.3 75 %, 50 %, 25 % output point at variable speed cor- – emergency operation test according to 2.3.6 responding to the propeller curve shall be demon- strated and documented. 2.4.3 Performance work’s test The test sequence has to be as follows: 2.3.5.3 Generator plants – 1 hour total at rated maximum continuous For generator plants further tests concerning load drop power, 100 % output at 100 % torque and 100 % and load raise as well as part load running will be speed required. This will be done on individual base, when approving the proposed test procedure, in order to take – 30 min. with 110 % power into account the special conditions of the specific – further operation at part load (totally 1h) with turbine resp. manufacturer. variable speed (for the case of essential main propulsion turbine) or at synchronous speed (for In general for generator plants, load drop from 100 % generator applications). to 0%, load increase from 0 % to 100 % and other load variations due to power demand, are not to result in a For special applications such as naval craft further or transient variation in rpm higher than +/- 10 %. The "in lieu of" testing may be required and will be agreed permanent speed fluctuation under stationary condi- upon between GL Headquarter and the manufacturer. tions shall not exceed +1 % of the rated speed. This depends on the special requirements of the Naval Administration. 2.3.6 Emergency operation test For further details see 2.3.5.

For emergency operating situation, the following tests 3. Boroscope inspection are to be performed: – quick start 3.1 A boroscope inspection is to be conducted after the type test according to 2.3 and the work's tests – override functions according to 2.4. After the type test normally the turbine unit will be The manufacturer has to demonstrate by proven ex- disassembled and the major components will be perience or design calculations that this emergency checked thoroughly. If such a procedure is applied, a operation will not cause malfunctions or damages to boroscope inspection is not necessary. the gas turbine. A boroscope inspection may be required also after sea 2.3.7 Type test report trials, on specific demand of an involved party or if irregularities are detected. The gas turbine manufacturer's records including all Boroscope inspection shall be conducted or witnessed monitored performance data shall be documented in a by an attending GL Surveyor, if required by GL. type test report, which is to be submitted for approval. In case that, irregularities, such as failures of compo- 3.2 Boroscope inspection of the following parts nents, seizing of parts, etc., occur, the cause has to be is to be conducted, if inspection ports are available: analysed and eliminated. The report on the dam- age/irregularities and the introduced countermeasures – compressor (blades and nozzles) has to be part of the report. – combustor III - Part 1 Section 4a F Thermal Turbomachinery/Gas Turbines Chapter 2 GL 2012 Page 4a–13

– fuel burners – at least 4 hours at rated speed

– high pressure turbine (blades and nozzles) – at least 2 hours at engine speed corresponding to – power turbine (blades and nozzles) normal continuous ahead cruising speed vM

3.3 In general no cracks or major wear shall be For special purpose gas turbines such as for non- seen in rotating parts after testing of a new gas turbine. essential propulsion and special considerations in Minor cracks, indents or tears in uncritical parts may accordance with specifications of the Naval Admini- be accepted based on documented acceptance criteria. stration may be applicable.

4. Sea trials 4.4 Special tests Crash-stop conditions shall be tested from full speed. 4.1 Trial procedure This is to be performed in the fastest time permitted by the controls of the gas turbine. The sea trials have to simulate the conditions in which the engine is expected to operate in service on board There shall be at least one simulation of a false turbine of the naval ship, including typical start-stop cycles, start with the following purging time before attempt- idling, acceleration, deceleration. ing a normal start. Minimum time required for restart The sea trial procedure is to be approved by GL prior of the turbine is to be checked in order to verify that to testing. start can be achieved before thermal interlock occurs.

4.2 No load running, adjustments 4.5 Vibration measurements

Prior to the start of the sea trials, the engine and the Vibration measurements are to be recorded during sea control and monitoring system are to demonstrate trials. The vibration signals are to be recorded for trouble free running at no load for 20 minutes. conditions taking into consideration the possible op- eration modii of the propulsion plant, e.g. controllable For generator gas turbines testing and adjustment of pitch propeller and constant turbine speed or fixed the load sharing characteristics, as far as applicable, pitch propeller and variable turbine speed. Clutch-in are to be carried out. Such test adjustments may also procedures, starting and stopping, etc. shall be investi- be carried out in the facilities of the Generator Set gated on request separately. Maker or during containerization.

4.3 Performance test 4.6 Final inspection As a minimum the engine is to be run for at least 6 Boroscope inspection according to 3. may be required hours as follows: by GL after sea trials.

III - Part 1 Section 4b B Thermal Turbomachinery/ Exhaust Gas Turbochargers Chapter 2 GL 2012 Page 4b–1

Section 4b

Thermal Turbomachinery/ Exhaust Gas Turbochargers

A. General d) material specifications including the mechanical and chemical properties for the rotating parts 1. Scope (shaft, turbine wheel, compressor wheel, blades) and the casing including welding details and The following Rules apply to the requirements for welding procedures for the rotating parts exhaust gas turbochargers fitted on diesel engines and describe the required procedures for drawing approval, e) technical specification for the turbocharger in- testing and shop approval. cluding maximum continuous operating condi- tions (maximum permissible values for the rota- 2. Definitions tional speed, exhaust gas and ambient tempera- ture as well as the permissible values regarding Regarding turbocharger speed conditions, the follow- vibration excited by the engine). The maximum ing definitions are to be applied: permissible values have to be defined by the – maximum permissible speed: manufacturer for a certain turbocharger type but maximum turbocharger speed, independent of shall be not less than the 110 % MCR values for application. the specific application. – maximum operational speed: f) operation and maintenance manuals speed at 110 % diesel engine output. g) details (name and address) of the subcontractors – operational speed: for rotating parts and casings speed at 100 % diesel engine output h) details (name and address) of the licensees, if representing MCR (maximum continuous rat- applicable, who are authorised by the licensor to ing) condition produce and deliver turbochargers of a certain The maximum operational speed and maximum per- type missible speed may be equal. i) type test report carried out in accordance with C.8. 3. Type approval j) test report or verification by calculation of the 3.1 In general turbochargers are type approved. A containment test, carried out in accordance with Type Certificate valid for 5 years will be issued in C.7. accordance with 3.2.

3.2 Documents for approval

The documents listed in the following are to be sub- B. Design and Installation mitted to GL. To facilitate a smooth and efficient approval process they shall be submitted electronically 1. General via GLOBE 1. In specific cases and following prior agreement with GL they can also be submitted in Turbochargers are to be designed to operate at least paper form in triplicate. under the ambient conditions given in Section 1, D. For every turbo charger type, the documents listed under a) to j) are to be submitted: 2. Basic design considerations a) cross-sectional drawings with main dimensions Basis of acceptance and subsequent certification of a b) drawings of rotating parts (shaft, turbine wheel, turbocharger is the drawing approval and the docu- compressor wheel, blades) and details of blade mented type test as well as the verification of the con- fixing tainment integrity. c) arrangement and flow diagram of lubrication The turbocharger rotors need to be designed according system to the criteria for natural burst speed. In general the burst speed of the turbine shall be lower than the burst –––––––––––––– speed of the compressor in order to avoid an excessive 1 Detailed information about GLOBE submission can be found turbine overspeed after compressor burst due to loss of on GL’s website www.gl-group.com/globe. energy absorption in the compressor. Chapter 2 Section 4b C Thermal Turbomachinery/ Exhaust Gas Turbochargers III - Part 1 Page 4b–2 GL 2012

3. Air inlet presentation of the work's own test results as well as by expertises of independent testing bodies. The air inlet of the turbocharger is to be fitted with a filter in order to minimise the entrance of dirt or water. The turbocharger casings are to be from ductile mate- rials (minimum 90 % ferritic structure) and properly 4. Hot surfaces heat-treated in order to achieve the required micro- structure and ductility as well as to remove residual 4.1 Parts with surface temperatures above 220 °C stresses. Deviations from the standard heat-treatment are to be properly insulated in order to minimise the have to be approved separately by GL. risk of fire if flammable oils, lubrication oils, or fuel come into contact with these surfaces. 1.2 Condition of supply and heat treatment

4.2 Pipe connections have to be located or Materials are to be supplied in the prescribed heat- shielded with collars in such a way that either spraying treated condition. Where the final heat treatment is to or dripping leak oil may not come into contact with be performed by the supplier, the actual condition in hot surfaces of more than 220 °C. which the material is supplied shall be clearly stated in the relevant Certificate. The final verification of mate- 4.3 Hot components in range of passageways or rial properties for components needs to be adapted and within the working area of turbochargers shall be coordinated according to production procedure. De- insulated or protected so that touching does not cause viations from the heat treatment procedures have to be burns. approved by GL separately. 1.3 Chemical composition and mechanical 5. Bearing lubrication properties 5.1 Bearing lubrication shall not be impaired by Materials and products have to satisfy the require- exhaust gases or by adjacent hot components. ments relating to chemical composition and mechani- cal properties specified in the GL Rules for Metallic 5.2 Leakage oil and oil vapours are to be evacu- Materials (II-1) or, where applicable, in the relevant ated in such a way that they do not come into contact manufacturer's specifications approved for the type in with parts at temperatures equal or above their self- each case. ignition temperature. 1.4 Non-destructive testing 5.3 For turbochargers which share a common lubrication system with the diesel engine and which Non-destructive testing shall be applied for the have got an electrical lubrication oil pump supply, it is wheels, blades and welded joints of rotating parts. recommended to install an emergency lubrication oil Another equal production control may be accepted for tank. welded joints. The testing shall be performed by the manufacturer and the results together with details of 5.4 A gas flow from turbocharger to adjacent the test method are to be evaluated according to rec- components containing explosive gases, e.g. crank- ognized quality criteria and documented in a Certifi- shaft casing shall be prevented by an adequate venti- cate. lating system. 1.5 Material Certificates Material Certificates shall contain at least the follow- ing information: C. Tests – quantity, type of product, dimensions where 1. Material tests applicable, types of material, supply condition and weight 1.1 General – name of supplier together with order and job numbers, if applicable Material testing is required for casings, shaft, com- pressor and turbine wheel, including the blades. The – construction number, where known materials used for the components of exhaust gas – manufacturing process turbochargers shall be suitable for the intended pur- – heat numbers and chemical composition pose and shall satisfy the minimum requirements of – supply condition with details of heat treatment the approved manufacturer's specification. – identifying marks All materials shall be manufactured by sufficiently – results of mechanical property tests carried out proven techniques according to state of the art, on material at ambient temperature whereby it is ensured that the required properties are achieved. Where new technologies are applied, a pre- Depending on the produced component material Cer- liminary proof of their suitability is to be submitted to tificates are to be issued by GL respectively the manu- GL. According to the decision of GL, this may be facturer. The required Certificates are summarized in done in terms of special tests for procedures and/or by Table 4b.1. III - Part 1 Section 4b C Thermal Turbomachinery/ Exhaust Gas Turbochargers Chapter 2 GL 2012 Page 4b–3

Table 4b.1 Material Certificates control procedure. For assessment of the balancing conditions the DIN ISO 1940 standard or comparable Components Type of Certificate 1 regulations may be referred to. Shaft GL Material Certificate 6. Bench test Rotors (compressor GL Material Certificate and turbine) 6.1 Each turbocharger has to pass a test run. The test run is to be carried out during 20 minutes with an Blades GL Material Certificate overload (110 % of the rated diesel engine output) on Casing Manufacturer Test Report the engine for which the turbocharger is intended. 1 Test Certificates are to be issued in accordance with GL This test run may be replaced by a separate test run of Rules for Principles and Test Procedures (II-1-1), Section 1, the turbocharger unit for 20 minutes at maximum H. operational speed and working temperature. The materials are to conform to specifications ap- 6.2 In case of sufficient verification of the turbo- proved in connection with the approval of the type in charger’s performance during the test, a subsequent each case. dismantling is required only in case of abnormalities If the manufacturer is approved according to D.2. as such as high vibrations or excessive noise or other manufacturer of mass produced exhaust gas turbo- deviations of operational parameters such as tempera- chargers fitted on diesel engines having a cylinder tures, speed, pressures to the expected operational bore ≤ 300 mm, the material properties of these parts data. may be covered by Manufacturer Inspection Certifi- On the other hand turbochargers shall be presented to cates and need not to be verified by a GL Surveyor. the GL Surveyor for inspection based upon an agreed spot check basis. 2. Testing of components The following tests as outlined in 3. – 5. may be car- 6.3 If the manufacturer is approved as a manufac- ried out and certified by the manufacturer for all ex- turer of mass produced turbochargers according to haust gas turbochargers. The identification of compo- D.2., the bench test can be carried out on an agreed nents subject to testing has to be ensured. On request, sample basis. In this case the Surveyor’s attendance at the documentation of the tests, including those of the test is not required. subcontractors' tests, are to be provided to the GL Surveyor for examination. 7. Containment test The tests as specified in 6. – 8. are to be performed in 7.1 The turbocharger has to fulfil containment presence of a GL Surveyor. requirements in case of rotor burst. GL reserves the right to review the proper perform- This requires that at rotor burst no part may penetrate ance and the results of the tests at any time to the the casing of the turbocharger. satisfaction of the Surveyor. The following requirements are applicable for an 3. Pressure tests approval of the type of turbochargers. Cooling water spaces as well as the emergency lubri- 7.2 The minimum speeds for the containment test cation oil system for gas inlet and gas outlet casings are defined as follows: are to be subjected to a hydrostatic pressure test of Compressor: ≥ 120 % of its maximum permissible pp = 4 bar, but not less than pp = 1,5 ⋅ pc (pp = test speed pressure; pc = design pressure). Turbine: ≥ 140 % of its maximum permissible 4. Overspeed test speed or the natural burst speed (which- All wheels (compressor and turbine) have to undergo ever is lower) an overspeed test for 3 minutes at 20 % over the The containment test has to be performed at working maximum operational speed at room temperature, or temperature. 10 % over the maximum permissible speed at maxi- The theoretical (design) natural burst speeds of com- mum permissible working temperature. If each wheel is individually checked by a GL approved non- pressor and turbine have to be submitted for informa- destructive testing method no overspeed test is re- tion. quired. 7.3 A numerical prove of sufficient containment Deviations are to be approved separately by GL. integrity of the casing based on calculations by means of a simulation model may be accepted, provided that: 5. Dynamic balancing – the numerical simulation model has been tested Each shaft and bladed wheel as well as the complete and it’s applicability/accuracy has been proven rotating assembly has to be dynamically balanced by direct comparison between calculation results individually in accordance with the approved quality and practical containment test for a reference Chapter 2 Section 4b D Thermal Turbomachinery/ Exhaust Gas Turbochargers III - Part 1 Page 4b–4 GL 2012

application (reference containment test). This manufacturing exhaust gas turbochargers fitted on GL proof has to be provided once by the manufac- approved mass produced diesel engines having a cyl- turer who wants to apply for acceptance of nu- inder bore of ≤ 300 mm may apply for the shop ap- merical simulation proval by GL Head Office. – the corresponding numerical simulation for the containment is performed for the same speeds, The shop approval is valid for 3 years with annual as specified for the containment test (see above) follow up audits. – the design of the turbocharger regarding the geometry and kinematics is similar to that of one 2.2 Upon satisfactory shop approval, the material turbocharger which has passed the containment tests according to C.1. for these parts may be covered test. In general totally new designs will call for by a Manufacturer Inspection Certificate and need not new containment tests to be verified by a Surveyor. – the application of the simulation model may give hints that containment speeds lower as In addition the bench test according to C.6. may be above specified may be more critical for the cas- carried out on a sample basis and need not to be veri- ing’s integrity, due to special design features fied by a GL Surveyor. and different kinematic behaviour. In such cases the integrity properties of containment for the casing shall be proven for the worst case 2.3 No GL Certificate will be issued for mass- produced turbochargers. Mass-produced turbochargers 7.4 In general a GL Surveyor or the Head Office will be mentioned with the serial number in the final has to be involved for the containment test. The Certificate intended for the diesel engine. documentation of the physical containment test as well as the report of the simulation results are to be submit- ted to GL within the scope of the approval procedure. 3. Manufacturing of exhaust gas turbocharg- ers under license agreement 8. Type test

8.1 The type test is to be carried out on a stan- 3.1 Manufacturers who are manufacturing ex- dard turbocharger. Normally the type test is a one hour haust gas turbochargers under a license agreement hot running test at maximum permissible speed and shall have a shop recognition of GL Head Office. maximum permissible temperature. After the test the turbocharger is to be dismantled and examined. The shop recognition can be issued in addition to a valid license agreement if the following requirements 8.2 Manufacturers who have facilities to test the are fulfilled: turbocharger on a diesel engine for which the turbo- charger is to be approved, may consider to substitute – The manufactured turbochargers have a valid the hot running test by a one hour test run at overload GL approval of the type for the licensor. (110 % of the rated diesel engine output).

9. Spare parts – The drawings and the material specification as well as the working procedures comply with the The rotating assembly parts (rotor, wheels and blades) drawings and specifications approved in connec- as well as turbocharger casings have to be replaced by tion with the turbocharger approval of the type spare parts which are manufactured by GL approved for the licensor. manufacturers according to the previously approved drawings and material specifications. The manufac- turer is to be recognized by the holder of the original 3.2 Upon satisfactory assessment in combination type approval. with a bench test carried out on a sample basis with GL Surveyor's attendance, the drawing approval and tests according to C.7. and C.8. are not required. The scope of the testing for materials and components has D. Shop Approvals to be fulfilled unchanged according to C.1. to C.6. 1. Materials and production 3.3 The shop recognition is valid for three years The manufacturers of the material as well as the pro- with annual follow up audits and can be granted, if duction procedures for the rotating parts and casings required in combination with an approval as manufac- have to be approved by GL. turer of mass-produced turbochargers. 2. Mass produced exhaust gas turbochargers The shop recognition becomes invalid if the licence 2.1 Manufacturers of mass-produced turbocharg- agreement expires. The licensor is obliged to inform ers who operate a quality management system and are the GL Head Office about the date of expiry. III - Part 1 Section 5 B Main Shafting Chapter 2 GL 2012 Page 5–1

Section 5

Main Shafting

A. General – calculation of torsional vibrations, compare Section 8 1. Scope – in special cases separate bending and axial vi- 1.1 The following Rules apply to standard and bration calculations may be required established types of shafting for main and auxiliary – for cast resin foundation of shaft components propulsion as well as lateral thrusters. Deviating de- arrangement and design of the adapting pieces signs require special approval by GL. and bolts, for details see D.5.7 1.2 For difficult or special operating conditions The submitted documentation shall contain all data adequate reinforcements have to be provided. necessary to enable the stresses to be evaluated. 1.3 GL reserves the right to call for propeller shaft dimensions in excess of those specified in this Section if the propeller arrangement results in in- creased bending stresses. B. Materials

1.4 In case of ships with ice classes, the strength- 1. Approved materials ening factors given in Section 9 are to be complied with. 1.1 Propeller, intermediate and thrust shafts to- gether with flange and clamp couplings are to be made 2. Documents for approval of forged steel; as far as applicable, couplings may be made of cast steel. Rolled round steel may be used for The following drawings are to be submitted to GL. To plain, flangeless shafts. facilitate a smooth and efficient approval process they shall be submitted electronically via GLOBE 1. In In general, the tensile strength of steels used for shaft- specific cases and following prior agreement with GL ing (shafts, flange couplings, bolts/fitted bolts) shall they can also be submitted in paper form in triplicate. be between 400 N/mm2 and 800 N/mm2. For dynami- GLOBE transmission is the preferred one: cally loaded parts of the shafting, designed in accor- dance to the formulas as given under C. and D., and – arrangement of the entire shafting, from the explicitly for the shafts themselves as well as for con- main engine coupling flange to the propeller necting / fitted bolts for flanged connections in general – detailed drawings and material data for all quenched and tempered steels shall be used with a 2 torque transmitting components, especially tensile strength of more than 500 N/mm . shafts, couplings and other component parts However, the value of Rm used for the calculation of – arrangement of the shaft bearings the material factor Cw in accordance with formula (2) – arrangement and detail drawings of the stern shall not exceed tube as well as bush bearings including stern – 600 N/mm2 for propeller shafts made of unal- tube sealing and the corresponding lubricating loyed steels oil system. 2 – calculation of the shaft alignment, including – 800 N/mm for all other applications alignment instruction, considering all static and Where materials with higher specified or actual tensile dynamic external forces acting on the shaft dur- strengths than the limitations given above are used, the ing operation (e.g. weight of couplings, propel- shaft dimensions derived from formulae (1) and (2) ler weight and propeller forces, toothing forces are not to be reduced accordingly. of gears, etc.). With consent of GL for shafting with intermediate shaft diameter < 200 mm the 1.2 Where in special cases wrought copper alloys alignment calculation may be waived. resistant to seawater are to be used for the shafting, consent of GL shall be obtained.

–––––––––––––– 1.3 For shafts made of fibre reinforced plastics 1 Detailed information about GLOBE submission can be found the GL Rules for Fibre Reinforced Plastics and Bond- on GL’s website www.gl-group.com/globe. ing (II-2-1), are applicable. Chapter 2 Section 5 C Main Shafting III - Part 1 Page 5–2 GL 2012

2. Testing of materials 2. Alternative calculation

2.1 All component parts of the shafting which are GL may accept alternative shaft calculations, e.g. transmitting the torque from the ship's propulsion are according to DIN 743. In such cases complete calcula- subject to the GL Rules for Materials and Welding (II- tions based on the applied standard are to be submitted 1), and are to be tested. This requirement is also appli- to GL for approval. cable for metal propeller shaft liners. Any alternative calculation has to include all relevant 2.2 Where propeller shafts running in seawater dynamic loads on the complete shafting system under are to be protected against seawater penetration not by all permissible operating conditions. Consideration a metal liner, but by plastic coatings, the coating tech- has to be given to the dimensions and arrangements of nique used is to be approved by GL. all shaft connections. Moreover, an alternative calcu- lation has to take into account design criteria for con- tinuous and transient operating loads (dimensioning for fatigue strength) and for peak operating loads C. Shaft Dimensioning (dimensioning for yield strength). The fatigue strength analysis may be carried out separately for different load assumptions, for example: 1. General 4 1.1 The following requirements apply to propul- − Low cycle fatigue criterion (typically < 10 ), i.e. sion shafts such as intermediate and propeller shafts of the primary cycles represented by zero to full traditional straight forged design and which are driven load and back, including reversing torque if ap- by rotating machines such as diesel engines, turbines plicable. This is addressed by formula (1) or electric motors. − High cycle fatigue criterion (typically > 107), i.e. 1.2 For shafts that are integral to equipment, such torsional vibration stresses permitted for con- as for gear boxes (see Section 6), podded drives, elec- tinuous operation as well as reverse bending trical motors and/or generators, thrusters, turbines and stresses. The limits for torsional vibration which in general incorporate particular design fea- stresses are given in Section 8. The influence of tures, additional criteria in relation to acceptable di- reverse bending stresses is addressed by the mensions have to be taken into account. For the shafts safety margins inherent in formula (1). in such equipment, the following requirements may only be applied for shafts subject mainly to torsion − The accumulated fatigue due to torsional vibra- and having traditional design features. Other limita- tion when passing through barred speed ranges tions, such as design for stiffness, high temperature, or other transient operational conditions with etc. are to be considered additionally. stresses beyond the permitted limits for continu- ous operation is addressed by the criterion for 1.3 Explicitly it will be emphasized that the fol- transient stresses in Section 8. lowing applications are not covered by the require- ments in this Section: 3. Minimum diameter − additional strengthening for shafts in ships, which are strengthened for navigation in ice (see The minimum shaft diameter is to be determined by Section 9) applying formula (1). − gearing shafts (see Section 6) Pw da ≥ d ≥ F ⋅ k ⋅ ⋅ Cw (1) − electric motor and generator rotor shafts 4 3 ⎡ ⎛ d ⎞ ⎤ − turbine rotor shafts (see Section 4a) n ⋅⎢1−⎜ i ⎟ ⎥ ⎢ ⎜ d ⎟ ⎥ ⎣ ⎝ a ⎠ ⎦ − crankshafts for internal combustion engines (see Section 3) d = minimum required outer diameter of shaft Additionally, all parts of the shafting are to be de- [mm] signed to comply with the requirements relating to torsional vibrations set out in Section 8. da = actual outer diameter of shaft [mm]

1.4 In general dimensioning of the shafting shall d = actual diameter of shaft bore [mm]. If the be based on the total rated installed power. i bore in the shaft is ≤ 0,4 ⋅ da, the expression 1.5 Where the geometry of a part is such that it 4 cannot be dimensioned in accordance with these for- ⎛ d ⎞ ⎜ i ⎟ mulae, special evidence of the mechanical strength of 1 − ⎜ ⎟ may be taken as 1,0 the part concerned is to be furnished to GL. ⎝ d a ⎠ III - Part 1 Section 5 C Main Shafting Chapter 2 GL 2012 Page 5–3

Pw = rated power of propulsion motor [kW], gear- − slot width e up to 0,1 ⋅ da box and bearing losses are not to be sub- tracted − end rounding at least 0,5 ⋅ e n = shaft speed at rated power [min–1] − 1 slot or 2 slots at 180° or 3 slots at 120° F = factor for the type of propulsion installation [–] Slots beyond these limitations require a) Propeller shafts a special strength consideration. = 100 for all types of installations b) Thrust shafts b) Intermediate and thrust shafts = 1,10 for thrust shafts external to engines = 95 for turbine installations, diesel near the plain bearings on both sides engine installations with hydrau- of the thrust collar, or near the axial lic slip couplings and electric bearings where a roller bearing design propulsion installations is applied = 100 for all other propulsion installa- c) Propeller shafts tions = 1,22 for propeller shafts with flange Cw = material factor [–] mounted or keyless taper fitted propel- lers, applicable to the shaft part be- 560 = (2) tween the forward edge of the after- R m + 160 most shaft bearing and the forward face of the propeller hub or shaft Rm = specified minimum tensile strength of the flange, but not less than 2,5 ⋅ d, 2 shaft material (see also B.1.) [N/mm ] for keyless, taper fitting, the method k = factor for the type of shaft [–] of connection has to be approved by GL a) Intermediate shafts = 1,26 for propeller shafts in the area speci- = 1,00 for plain sections of intermediate fied for k = 1,22 if the propeller is shafts with integral forged flanges or keyed to the tapered propeller shaft with shrink-fitted keyless coupling flanges. For shafts with high vibratory = 1,40 for propeller shafts in the area speci- torques, the diameter in way of shrink fied for k = 1,22 if the shaft inside the fitted couplings should be slightly in- stern tube is lubricated with grease creased, e.g. by 1 or 2 %. = 1,15 for propeller shafts between forward = 1,10 for intermediate shafts where the cou- end of aftermost bearing and forward pling flanges are mounted on the ends end of fore stern tube seal. The portion of the shaft with the aid of keys. At a of the propeller shaft located forward of the stern tube seal can gradually be distance of at least 0,2 ⋅ d from the end reduced to the size of the intermediate of the keyway, such shafts can be re- shaft duced to a diameter corresponding to k = 1,0 4. An approval of a shaft diameter lower than = 1,10 for intermediate shafts with radial calculated according to formula (1) is possible under holes with a diameter of no more than the following conditions: 0,3 ⋅ d . Intersections between radial a – the fatigue strength values of the used material and eccentric axial holes require a spe- in the operating medium have to be submitted cial strength consideration. – an advanced calculation method (such as men- = 1,15 for intermediate shafts designed as tioned in 2.) has to be applied multi-splined shafts where d is the outside diameter of the splined shaft. 5. Shafts made of pipes Outside the splined section, the shafts can be reduced to a diameter corre- For pipe shafts with relative thick walls the problem of sponding to k = 1,0 buckling needs generally not to be investigated. For thin wall and large diameter shafts buckling behaviour = 1,20 for intermediate shafts with longitudi- must be checked additionally. For isotropic materials nal slots within the following limita- the following formula for the critical torque applies: tions: 0,272⋅ E ⋅ 2⋅ r 0,5 ⋅ t 2,5 ⋅ π − slot length up to 0,8 ⋅ da m Mtcrit = C ⋅ [Nm] (2a) (1−ν 2 ) 0,75 − inner diameter up to 0,8 ⋅ da Chapter 2 Section 5 D Main Shafting III - Part 1 Page 5–4 GL 2012

C = factor for special conditions For intermediate and thrust shafts, the radius at forged = 1,0 generally flanges is to be at least 8 % of the calculated minimum diameter for a full shaft at the relevant location. The E = modulus of elasticity [N/mm2] radius at the aft propeller shaft flange shall be at least ν = Poisson's ratio 12,5 % of the calculated minimum diameter for a full shaft at the relevant location. t = thickness of pipe wall The surface quality of the shaft has to be chosen ac- = (d – d ) ⋅ 0,5 [mm] a i cording to the type of loads and the notch sensitivity rm = average radius of the pipe [mm] of the material. In the areas between the bearings a minimum quality of the arithmetic mean roughness of = 0,25 (da + di) Ra = 10 − 16 μm, at bearing running surfaces and The design criterion is: transition zones a value of Ra = 1,6 − 2,5 μm will be in general required. 3,5⋅≤ Mttcrit M (2b) 2. Shaft tapers and propeller nut threads Mt = nominal torque at maximum continuous rat- ing [Nm] 2.1 Keyways in the shaft taper for the propeller are to be designed in a way that the forward end of the 6. Consideration of shock loads groove makes a gradual transition to the full shaft If the Class Notation SHOCK shall be assigned to the section. In addition, the forward end of the keyway naval ship, the influence of the additional accelera- shall be spoonshaped. The edges of the keyway at the tions caused by shock loads (shock spectra), are to be surface of the shaft taper for the propeller are not to be defined by the Naval Administration. sharp. The forward end of the rounded keyway has to lie well within the seating of the propeller boss. Threaded holes for securing screws for propeller keys shall be located only in the aft half of the keyway (see D. Design Fig. 5.1).

1. General 2.2 In general, tapers for securing flange cou- plings which are jointed with keys shall have a conic- The design of the shafts should aim to achieve smooth ity of between 1 : 12 and 1 : 20. See Section 7a for stress distribution avoiding high stress concentration details of propeller shaft tapers on the propeller side. spots. Changes in diameter are to be effected by tapering or 2.3 The outside diameter of the threaded end for ample radiusing. Radii are to be at least equal to the the propeller retaining nut shall not be less than 60 % change in diameter. of the calculated bigger taper diameter.

X r6 ~ 0,5 b

d Section E - E

A B C D

E E r1 < r2 < r3 < r4

Standard values of r b 5 r r r r d r 1 2 3 4 5 r5 r5 r5 r5 up to 150 3 up to 250 4 up to 450 5 A B C D from 450 6 Sections: A - A B - B C - C D - D a ( a ~ b ) Detail X Fig. 5.1 Design of keyway in propeller shaft III - Part 1 Section 5 D Main Shafting Chapter 2 GL 2012 Page 5–5

3. Propeller shaft protection 4. Coupling connections

3.1 Sealing 4.1 Definitions In the formulae (4), (5), (6) and (7), the following At the stern tube ends propeller shafts with oil or symbols are used: grease lubrication are to be fitted with seals of proven efficiency and approved by GL, see also the require- A = effective area of shrink-fit seating [mm2] ments applicable to the external sealing of the stern tube in the context of the propeller shaft survey pre- cA = coefficient for shrink-fitted joints [–], de- scribed in the Classification and Surveys (III-0), pending on the kind of driving unit Section 3. = 1,0 for geared diesel engine and turbine The securing at stern tube, shaft line or propeller (e.g. drives chrome steel liner) shall guarantee a permanent tight- = 1,2 for direct coupled diesel engine drives ness. C = conicity of shaft ends [–] GL reserves the right to demand corresponding veri- fications. difference in taper diameters = length of cone For protection of the sealing a rope guard shall be provided. d = shaft diameter in area of clamp type cou- pling [mm] The propeller boss seating is to be effectively pro- tected against the ingress of seawater. This seal can ds = diameters of fitted bolts [mm] be dispensed with if the propeller shaft is made of corrosion-resistant material. dk = inner throat diameter of necked-down bolts [mm] In the case of Class Notation IW, the seal is to be fitted with a device by means of which the bearing D = diameter of pitch circle of bolts [mm] clearance can be measured when the vessel is afloat. f = coefficient for shrink-fitted joints [–]

3.2 Shaft liners Q = peripheral force at the mean joint diameter of a shrink fit [N] 3.2.1 Propeller shafts which are not made of cor- n = shaft speed [min–1] rosion-resistant material and which run in seawater 2 are to be protected against ingress with seawater by p = interface pressure of shrink fits [N/mm ] seawater-resistant metal liners or other liners ap- P = rated power of the driving motor [kW] proved by GL and by proven seals at the propeller. w sfl = flange thickness in area of bolt pitch circle 3.2.2 Metal liners in accordance with 3.2.1, which [mm] run in seawater, are to be made in a single piece. Only with the expressed consent of GL the liner may S = safety factor against slipping of shrink fits in consist of two or more parts, provided that the abut- the shafting [–] ting edges of the parts are additionally sealed and = 3,0 between motor and gear protected, after fitting, by a method approved by GL to guarantee water-tightness. Such a possibility are = 2,5 for all other applications special coatings. Such joints will be subject of special tests to prove their effectiveness. T = propeller thrust respectively axial force [N] z = number of fitted or necked-down bolts [–] 3.2.3 Minimum wall thickness of shaft liners Rm = tensile strength of fitted or necked-down bolt The minimum wall thickness s [mm] of metal shaft material [N/mm2] liners in accordance with 3.2.1 is to be determined using the following formula: µo = coefficient of static friction [–] = 0,15 for hydraulic shrink fits s = 0,03 ⋅ d + 7,5 (3) = 0,18 for dry shrink fits d = shaft diameter under the liner [mm] Θ = half conicity of shaft ends [–]

In the case of continuous liners, the wall thickness = C between the bearings may be reduced to 0,75 ⋅ s. 2 Chapter 2 Section 5 D Main Shafting III - Part 1 Page 5–6 GL 2012

4.2 Coupling flanges difference between the lowest respectively highest diameter for the bore and the shaft according to the The thickness of coupling flanges on the intermediate manufacturing drawings. The contact pressure and thrust shafts as well as on the forward end of the 2 propeller shaft is to be equal to at least 20 % of the p [N/mm ] in the shrunk-on joint to achieve the re- quired safety margin may be determined by applying calculated minimum diameter of a solid shaft at the formulae (6) and (7). relevant location. Where propellers are connected by means of a forged 22 22 2 flange with the propeller shaft, the thickness of this Θ ⋅+⋅TfcQT( A ⋅+) −Θ⋅ T flange shall be at least 25 % of the calculated mini- p = (6) mum diameter of a solid shaft at the relevant location. Af⋅ The thickness of mentioned flanges shall not be less T has to be introduced as positive value if the propel- than the Rule diameter of the fitted bolts, as far as ler thrust increases the surface pressure at the taper. their calculation is based on the same material tensile Change of direction of propeller thrust is to be ne- strength as applied for the shaft material. glected as far as power and thrust are essentially less.

4.3 Bolts T has to be introduced as negative value if the propel- ler thrust reduces the surface pressure at the taper, 4.3.1 The bolts used to connect flange couplings e.g. for tractor propellers. are normally to be designed as fitted bolts. The mini- mum diameter d of fitted bolts at the coupling flange 2 s ⎛ μ o ⎞ 2 faces is to be determined by applying the formula: f = ⎜ ⎟ − Θ (7) ⎝ S ⎠

6 10 ⋅ Pw d s = 16 ⋅ (4) 5. Shafting bearings n ⋅ D ⋅ z ⋅ R m 5.1 Arrangement of shaft bearings The coupling bolts shall be tightened so that flange contact will not be lost under both shaft bending Drawings showing all shaft bearings, like stern tube moment and astern thrust. bearings, intermediate bearings and thrust bearings shall be submitted for approval separately, if the 4.3.2 Where, in special circumstances, the use of design details are not visible at the shafting arrange- fitted bolts is not feasible, GL may agree to the use of ment drawings. The permissible bearing loads are to an application of an equivalent frictional transmis- be indicated. The lowest permissible shaft speed also sion. has to be considered.

4.3.3 The minimum thread root diameter dk of the Shaft bearings both inside and outside the stern tube connecting bolts used for clamp-type couplings is to are to be so arranged that each bearing is subjected to be determined using the formula: positive reaction forces, irrespective of the ship’s loading when the plant is at operating state tempera- 6 ture. 10⋅ Pw d12k =⋅ (5) nd⋅⋅⋅ z Rm By appropriate spacing of the bearings and by the alignment of the shafting in relation to the coupling flange at the engine or gearing, care is to be taken to 4.3.4 The shaft of necked-down bolts shall not be ensure that no undue shear forces or bending mo- less than 0,9 times the thread root diameter. If, be- ments are excerted to the crankshaft or gear shafts sides the torque, the bolted connection has to transmit when the plant is at operating state temperature. By considerable additional forces, the bolts shall be spacing the bearings sufficiently far apart, steps are reinforced accordingly. also to be taken to ensure that the reaction forces of line or gear shaft bearings are not significantly af- 4.4 Shrink-fitted couplings fected should the alignment of one or more bearings Where shafts are connected by keyless shrink fitted be altered by hull deflections or by displacement or couplings (flange or sleeve type), the dimensioning of wear of the bearings themselves. these shrink fits shall be chosen in a way that the Guide values for the maximum permissible distance maximum von Mises equivalent stress in all parts will not exceed 80 % of the yield strength of the specific between bearings Amax [mm] can be determined using materials during operation and 95 % during mounting formula (8): and dismounting. For the calculation of the safety margin of the con- A max = K1 ⋅ d (8) nection against slippage, the maximal clearance will be applied. This clearance has to be derived as the d = diameter of shaft between bearings [mm] III - Part 1 Section 5 D Main Shafting Chapter 2 GL 2012 Page 5–7

K1 = 450 for oil-lubricated white metal 5.2.3 Where the propeller shaft inside the stern bearings tube runs in bearings made of lignum vitae, rubber or plastic approved for use in water-lubricated stern tube = 280 for grey cast iron, grease-lubri- bearings, the length of the after stern tube bearing cated stern tube bearings should be approximately 4 ⋅ da and that of the for- ward stern tube bearing approximately 1,5 ⋅ d . = 280 – 350 for water-lubricated rubber a bearings in stern tubes and shaft A reduction of the bearing length may be approved if brackets (upper values for spe- the bearing is shown by means of bench tests to have cial designs only) sufficient load-bearing capacity.

Where the shaft speed exceeds 350 min–1 it is re- 5.2.4 Where the propeller shaft runs in grease- commended that the maximum bearing spacing is lubricated, grey cast iron bushes the lengths of the determined in accordance with formula (9) in order to after and forward stern tube bearings should be ap- avoid excessive loads due to bending vibrations. In proximately 2,5 ⋅ da and 1,0 ⋅ da respectively. limiting cases a bending vibration analysis for the shafting system is recommended. The peripheral speed of propeller shafts shall not exceed: d – 2,5 to maximum 3 m/s for grease-lubricated A = K ⋅ (9) grey cast iron bearings max 2 n – 6 m/s for water-lubricated rubber bearings n = shaft speed [min-1] – 3 to maximal 4 m/s for water lubricated lignum vitae bearings K2 = 8 400 for oil-lubricated white metal bearings 5.2.5 If roller bearings are provided, the require- ments of 5.3.2 have to be considered = 5 200 for grease-lubricated, grey cast iron bearings and for rubber bear- 5.3 Intermediate bearings ings inside stern tubes and tail shaft brackets 5.3.1 Plain bearings For intermediate bearings shorter bearing lengths or In general, the distance between bearings should not higher specific loads as defined in 5.2 may be agreed be less than 60 % of the maximum permissible dis- with GL. tance as calculated using formula (8) or (9) respec- tively. 5.3.2 Roller bearings For the case of application of roller bearings for shaft 5.2 Stern tube bearings lines the design is to be adequate for the specific requirements. For shaft lines significant deflections 5.2.1 Inside the stern tube the propeller shaft shall and inclinations have to be taken into account. Those normally be supported by two bearing points. In short shall not have adverse consequences. stern tubes the forward bearing may be dispensed with. In such cases generally at least one free- For application of roller bearings the required mini- standing journal shaft bearing should be provided. mum loads as specified by the manufacturer are to be observed.

5.2.2 Where the propeller shaft inside the stern The minimum L10a (acc. ISO 281) lifetime has to be tube runs in oil-lubricated white metal bearings or in suitable with regard to the specified overhaul inter- synthetic rubber or reinforced resin or plastic materi- vals. als approved for use in oil-lubricated stern tube bear- ings, the lengths of the after and forward stern tube 5.4 Bearing lubrication bearings shall be approximately 2 ⋅ da and 0,8 ⋅ da respectively. 5.4.1 Lubrication and matching of materials of the plain and roller bearings for the shafting have to meet The length of the after stern tube bearing may be the operational demands of seagoing ships. reduced to 1,5 ⋅ d provided that the contact load, a 5.4.2 Lubricating oil or grease is to be introduced which is calculated from the static load and allowing into the stern tube in such a way as to ensure a reli- for the weight of the propeller is less than 0,8 MPa able supply of oil or grease to the forward and after for white metal bearings and less than 0,6 MPa for stern tube bearing. bearings made of synthetic materials. With grease lubrication, the forward and after bear- For approved materials higher surface pressure values ings are each to be provided with a grease connec- may be applied. tion. Wherever possible, a grease gun driven by the Chapter 2 Section 5 D Main Shafting III - Part 1 Page 5–8 GL 2012

shaft is to be used to secure a continuous supply of − If roller bearings are provided, additional vibra- grease. Where the shaft runs in oil inside the stern tion measurements have to be carried out regu- tube, a header tank is to be fitted at a sufficient height larly and to be documented. The scope of the above the ship's load line. It shall be possible to measurements and of the documentation has to check the filling of the tank at any time. be agreed with GL specifically for the plant.

The temperature of the after stern tube bearing (in 5.6.2 The requirements for the initial survey of general near the lower aft edge of the bearing) is to this system as well as for the checks at the occasion be indicated. Alternatively, with propeller shafts less of annual and Class Renewal surveys are defined in than 400 mm in diameter the stern tube oil tempera- the relevant CM-PS Record File (Form F233 AE). ture may be indicated. In this case the temperature sensor is to be located in the vicinity of the after stern 5.6.3 If the requirements according to 5.6.1 and tube bearing. 5.6.2 are fulfilled, the Class Notation CM-PS may be assigned. 5.4.3 In the case of ships with automated machin- ery, GL Rules for Automation (III-1-3b) have to be complied with. 5.7 Cast resin mounting

5.5 Stern tube connections 5.7.1 The mounting of stern tubes and stern tube bearings made of cast resin and also the seating of

intermediate shaft bearings on cast resin parts is to be Oil-lubricated stern tubes are to be fitted with filling, carried out by GL-approved companies in the pres- testing and drainage connections as well as with a ence of a GL Surveyor. vent pipe. Only GL-approved cast resins may be used for seat- Where the propeller shaft runs in seawater, a flushing ings. line is to be fitted in front of the forward stern tube bearing instead of the filling connection. If required, The installation instructions issued by the manufac- this flushing line shall also act as forced water lubri- turer of the cast resin have to be observed. cation. 5.7.2 For further details see GL Guidelines for the 5.6 Condition monitoring of propeller shaft at Seating of Propulsion Plants and Auxiliary Machin- stern tube ery (VI-4-3) and GL Guidelines for the Approval of Reaction Plastics and Composite Materials for the 5.6.1 Where the propeller shaft runs within the Seating and Repair of Components (VI-9-5). stern tube in oil the possibility exists to prolong the intervals between shaft withdrawals. For this purpose 5.8 Shaft alignment the following design measures have to be provided: 5.8.1 It has to be verified by alignment calculation − a device for measurement of the temperature of that the requirements for shaft-, gearbox- and engine the stern tube bearings and the sea water tem- bearings are fulfilled in all relevant working condi- perature (and regular documentation of meas- tions of the propulsion plant. At this all essential ured values), compare 5.4.2 static, dynamic and thermal effects have to be taken − a possibility to determine the oil consumption into account. within the stern tube (and regular documenta- The calculation reports to be submitted are to include tion) the complete scope of used input data and have to − an arrangement to measure the wear down of disclose the resulting shaft deflection, bending stress the aft bearing and bearing loads and have to document the compli- ance with the specific requirements of the component − a system to take representative oil samples at manufacturer. the rear end of the stern tube under running conditions for analysis of oil quality (aging ef- 5.8.2 For the execution of the alignment on board fects and content of H2O, iron, copper, tin, sili- an instruction has to be created which lists the per- con, bearing metal, etc.) and suitable recepta- missible gap and sag values for open flange connec- cles to send samples to accredited laboratories. tions respectively the "Jack-up" loads for measuring (The samples shall be taken at least every six the bearing loads. months.) 5.8.3 Before the installation of the propeller shaft − a written description of the right procedure to the correct alignment of the stern tube bearings is to take the oil samples be checked. − a test device to evaluate the water content in the The final alignment on board has to be checked by lubricating oil on board (to be used once a suitable methods in afloat condition in presence of month) the GL Surveyor. III - Part 1 Section 5 F Main Shafting Chapter 2 GL 2012 Page 5–9

5.9 Shaft locking devices Dimensioning to be performed against nominal torque with a safety of 3. 5.9.1 A locking device acc. to Section 2, E.2.4 has to be provided at each shaftline of multiple-shaft – failure due to fatigue (high cycle) systems. As far as the shaft is not exposed to bending stresses fatigue analysis may be carried out for 5.9.2 The locking device is at least to be designed nominal torque plus 30 % torsional vibration to prevent the locked shaft from rotating while the torque. ship is operating with the remaining shafts at reduced power. This reduced power has to ensure a ship speed – buckling failure mode that maintains the manoeuvring capability of the ship Dimensioning may be estimated for a load of 3 in full scope, in general not less than 8 kn. times the nominal torque and in accordance to the formulas in 2. 5.9.3 If the locking device is not designed for the full power/speed of the remaining shafts, this opera- For the strength analysis the nominal strength of the tional restriction has to be recognizable for the opera- material has to be reduced by the factor 0,7 in order tor by adequate signs. to compensate random influence factors such as geometrical and production inaccuracies as well as 5.10 Shaft earthing environmental factors (moisture, temperature).

The calculation of the stress may be performed on the Shaft earthing has to be provided according to basis of accepted analytical methods such as CLT Section 3, E.6.4. (Classical Laminate Theory) or FEM models. With these stresses as input a set of failure modi in relation to fibre and interfibre failure shall be checked. This set of failure modi has to be coherent, i.e. a complete E. Balancing and Testing and accepted theory 3.

1. The imbalance of the shafts, e.g. because of 2. Buckling failure eccentric drilling hole of hollow shafts has to be within the quality range G 16 according to ISO 1940- For shafts made of anisotropic materials, such as 1 2, as far as applicable. winded shafts of fibre laminate, buckling strength can be checked for the critical torque by the following 2. Shaft liners formula: 5/8 3 5/4 9/4 3/8 Prior to fitting, shaft liners are to be subjected to a π rtE⋅⋅ ⎛⎞Ey MC=⋅ ⋅mx ⋅⎜⎟ [Nm] tcrit s ⎜⎟ hydraulic tightness test at 2 bar pressure in the finish- 6000 0,5⎝⎠ 1 −νxy ⋅ν yz machined condition. 3. Stern tubes Cs = factor depending on boundary conditions of support Prior to fitting cast stern tube parts are to be subjected to a hydraulic tightness test at 2 bar pressure in the = 0,800 for free ends finish-machined condition. A further tightness test is = 0,925 ends simply supported to be carried out after fitting. 2 For stern tubes fabricated from welded steel plates, it Ex = modulus of elasticity in x-direction [N/mm ] is sufficient to test for tightness during the pressure Ey = modulus of elasticity in transverse direction tests applied to the hull spaces passed by the stern [N/mm2] tube. A = unsupported length of shaft [mm]

rm, t = see C.5. F. Special Requirements for Fibre Laminate Shafts νxy = Poisson's ratio of the laminate in longitudi- nal direction 1. Theoretical strength calculation νyx = Poisson's ratio of the laminate in peripheral direction The strength calculation must at least cover the fol- lowing failure modi in conjunction with the given The design criteria is: corresponding load cases: – statical failure 3,5 ⋅ Mt ≤ Mtcrit –––––––––––––– 2 "Mechanical vibration; Balance quality requirements of rigid –––––––––––––– rotors; Determination of permissible residual unbalance". 3 VDI calculation scheme under preparation. Chapter 2 Section 5 F Main Shafting III - Part 1 Page 5–10 GL 2012

Mt = nominal torque at maximum continuous 4. Fire protection rating [Nm] If fire protection requirements are relevant for com- posite shafting, specifically in the cases of penetra- 3. Experimental strength investigation tion of fire protection bulkheads and/or redundant Experimental strength investigation has to be pro- propulsion, appropriate provisions shall be taken to vided on request. Specifically: ensure the required properties in consent with GL. – testing of samples, if necessary for verification of material data 5. Final documentation – prototype testing/process checking for verifica- After finalising manufacturing of the components an tion of the theoretical analysis in presence of a updated documentation in the form of a list of all GL Surveyor definitive valid analyses and documents is to be sub- – after a year or 3000 operating hours, whichever mitted to GL. The documentation shall refer to the is reached earlier, a visual examination and op- status quo and take into account all alterations or tionally a crack or delamination check of the optimisations introduced during designing and manu- fibre laminate components is to be carried out facturing process as well as the achieved and meas- by a GL Surveyor ured properties. III - Part 1 Section 6 C Gears, Couplings Chapter 2 GL 2012 Page 6–1

Section 6

Gears, Couplings

A. General 1.2 Couplings in the main propulsion plant shall be made of steel, cast steel or nodular cast iron with a 1. Scope mostly ferritic matrix. Grey cast iron or suitable cast aluminium alloys may also be permitted for lightly 1.1 These Rules apply to spur, planetary and stressed external components of couplings and the bevel gears and to all types of couplings for incorpora- rotors and casings of hydraulic slip couplings. tion in the main propulsion plant or essential auxiliary machinery as specified in Section 1, B.4. The design 1.3 The gears of essential auxiliary machinery requirements laid down here may also be applied to according to Section 1, B.4. are subject to the same gears and couplings of auxiliary machinery other than requirements as those specified in 1.1 as regards the mentioned in Section 1, B.4. materials used. For gears intended for auxiliary ma- chinery other than that mentioned in Section 1, B.4. 1.2 Application of these requirements to the other materials may also be permitted. auxiliary machinery couplings mentioned in 1.1 may normally be limited to a general approval of the par- 1.4 Flexible coupling bodies for essential auxil- ticular coupling type by GL. Regarding the design of iary machinery according to Section 1, B.4. may gen- elastic couplings for use in generator sets, reference is erally be made of grey cast iron, and for the outer made to G.4.4.6. coupling bodies a suitable aluminium alloy may also be used. However, for generator sets use shall only be 1.3 For the dimensional design of gears and cou- made of coupling bodies preferably made of nodular plings with ice class, see Section 9. cast iron with a mostly ferritic matrix, of steel or of cast steel, to ensure that the couplings are well able to 2. Documents for approval withstand the shock torques occasioned by short- circuits. GL reserves the right to impose similar re- Assembly and sectional drawings together with the quirements on the couplings of particular auxiliary necessary detail drawings and parts lists are to be drive units. submitted to GL. To facilitate a smooth and efficient approval process they shall be submitted electronically 2. Testing of materials via GLOBE 1. In specific cases and following prior agreement with GL they can also be submitted in All gear and coupling components which are involved paper form in triplicate. in the transmission of torque and which will be in- stalled in the main propulsion plant have to be tested under surveillance of GL in accordance with the GL Rules for Metallic Materials (II-1) and a GL Material B. Materials Certificate has to be provided. The same applies to the materials used for gear components with major torque 1. Approved materials transmission function of gears and couplings in gen- erator drives. 1.1 Shafts, pinions, wheels and wheel rims of gears in the main propulsion plant are preferably to be Suitable proof is to be submitted for the materials used made of forged steel. Rolled steel bar may also be for the major components of the couplings and gears used for plain, flangeless shafts. Gear wheel bodies of all other functionally essential auxiliary machines in accordance with Section 1, B.4. This proof may may be made of grey cast iron 2 , nodular cast iron or take place by a Manufacturer Inspection Certificate of may be fabricated from welded steel plate with steel or the steelmaker. cast steel hubs. For the material of the gearings the requirements according to ISO 6336, Part 5 are to be considered. C. Calculation of the Load-Bearing Capacity of Gear Teeth

–––––––––––––– 1. General 1 Detailed information about GLOBE submission can be found on GL’s website www.gl-group.com/globe. 1.1 Components of the gearing system are: 2 The peripheral speed of cast iron gear wheels shall generally – gear not exceed 60 m/s, that of cast iron coupling clamps or bowls, 40 m/s. – equipment for the gear lubrication and control oil Chapter 2 Section 6 C Gears, Couplings III - Part 1 Page 6–2 GL 2012

– cooling water equipment 2.1.2 For gears in the main propulsion plant proof – system for engaging/disengaging of the sufficient mechanical strength of the roots and flanks of gear teeth in accordance with the formulae 1.2 Gears have to be designed to meet the sound contained in this Section is linked to the requirement level defined in the building specification. The follow- that the accuracy of the teeth ensures sufficiently ing design principles for low-noise gears are to be smooth gear operation combined with satisfactory considered: exploitation of the dynamic loading capacity of the teeth. – elastic mounting of the gear directly on the ship structure – fixed mounting of gear and drive unit on an For this purpose, the magnitude of the individual pitch intermediate framing which is elastically error fp and of the total profile error Ff for peripheral mounted on the ship structure speeds at the pitch circle up to 25 m/s shall generally – flexible couplings to the drive unit and to the conform to at least quality 5 as defined in DIN 3962 or propeller shaft 4 to ISO 1328, and in the case of higher peripheral – use of low-noise types of toothing, such as dou- speeds generally to at least quality 4 as defined in ble helical gearing DIN 3962 or 3 to ISO 1328. The total error of the tooth trace f should conform at least to quality 5 to – installation of low-noise components, e.g. rotary Hß DIN 3962, while the parallelism of axis shall at least screw pumps, etc. for the gear lubrication. In- meet the requirements of quality 5 according to stallation of pumps with small suction height to DIN 3964 or 4 according to ISO 1328 respectively. avoid cavitation noise

2. Calculation of load capacity for spur and Prior to running-in the surface roughness Rz of the bevel gears tooth flanks of gears made by milling or by shaping 2.1 General shall generally not exceed 10 µm. In the case where the tooth profile is achieved by e.g. grinding or lap- 2.1.1 The sufficient load capacity of the gear-tooth ping, the surface roughness should generally not ex- system of main and auxiliary gears in ship propulsion ceed 4 μm. The tooth root radius ρao on the tool refer- systems is to be demonstrated by load capacity calcu- ence profile is to be at least 0,25 · mn. lations according to the international standards ISO 6336, ISO 9083 or DIN 3990 for spur gears respec- tively ISO 10300 or DIN 3991 for bevel gears while GL reserves the right to call for proof of the manufac- maintaining the safety margins stated in Table 6.1 for turing accuracy of the gear-cutting machines used and flank and root stresses. for testing of the method used to harden the gear teeth.

Table 6.1 Minimum safety margins for flank and root stress

Case Application Boundary conditions SH SF 1.1 Modulus mn ≤ 16 1,3 1,8 1.2 Modulus mn > 16 0,024 mn + 0,916 0,02 mn + 1,48 1.3 Gearing in ship propulsion In the case of two systems and generator drive mutually independent 1,2 1,55 systems main propulsion systems up to an input torque of 8000 Nm 2.1 Gears in auxiliary drive system which are subjected 1,2 1,4 to dynamic load 2.2 Gears in auxiliary drive systems used for dynamic 1,3 1,8 positioning (Class Notation DP) 2.3 Gears in auxiliary drive 4 systems which are subjected NL ≤ 10 1,0 1,0 to static load Note If the fatigue bending stress of the tooth roots is increased by special technique approved by GL, e.g. by shot peening, for case-hardened toothing with modulus mn ≤ 10 the minimum safety margin SF may be reduced up to 15 % with consent of GL.

III - Part 1 Section 6 C Gears, Couplings Chapter 2 GL 2012 Page 6–3

3. Symbols, terms and summary of input Ra = arithmetic mean roughness [μm] data RzF = mean peak to valley roughness of root 3.1 Indices [μm] 1 = pinion RzH = mean peak to valley roughness of flank 2 = wheel [μm] m = in the mid of the face width SF = safety factor against tooth breakage [–] 2 n = normal plane SFG = tooth root stress limit [N/mm ] t = transverse plane SH = safety factor against pittings [–] 0 = tool T = torque [Nm] u = gear ratio [–] 3.2 Parameters x = addendum modification coefficient [–] a = centre distance [mm] b = face width [mm] xhm = mean addendum modification coefficient [–] beh = effective face width (bevel gears) [mm] xsm = thickness modification coefficient (bevel Bzo = measure for shift of datum line gears) [–] d = standard pitch diameter [mm] YF = tooth form factor (root) [–] da = tip diameter [mm] YNT = live factor (root) [–] df = root diameter [mm] Yδ rel T = relative notch sensitivity factor [–] Ft = circular force at reference circle [N] YR rel T = relative surface condition factor [–] F = initial equivalent misalignment [μm] βx YS = stress correction factor [–] f = normal pitch error [μm] pe YST = stress correction factor for reference test ff = profile form error [μm] gears [–] * YX = size factor for tooth root stress [–] ha0 = addendum coefficient of tool [–] * Yβ = helix angle factor for tooth root stress [–] hf0 = dedendum coefficient of tool [–] * z = number of teeth [–] hFfP0 = utilized dedendum coefficient of tool [–] ZE = elasticity factor [–] KA = application factor [–] ZH = zone factor (contact stress) [–] KFα = transverse load distribution factor (root stress) [–] ZL = lubricant factor [–]

KFß = face load distribution factor (root stress) ZNT = live factor (contact stress) [–] [–] Zv = speed factor [–] K = transverse load distribution factor (contact Hα ZR = roughness factor [–] stress) [–] ZW = work-hardening factor [–] KHß = face load distribution factor (contact stress) [–] ZX = size factor (contact stress) [–] Z = helix angle factor (contact stress) [–] KHß-be = bearing factor (bevel gears) [–] β Zε = contact ratio factor (contact stress) [–] Kv = dynamic factor [–] α = normal pressure angle [°] Kγ = load distribution factor [–] n mn = normal modul [mm] αpr = protuberance angle [°] mnm = mean normal modul (bevel gear) [mm] β = helix angle [°] n = number of revolutions [min-1] βm = mean helix angle (bevel gears) [°]

NL = number of load cycles [–] ϑoil = oil temperature [°C] P = transmitted power [kW] ν40 = kinematic viscosity of the oil at 40 °C pr = protuberance at tool [mm] [mm2/s]

Q = toothing quality, acc. to DIN [–] ν100 = kinematic viscosity of the oil at 100 °C q = machining allowance [mm] [mm2/s] Chapter 2 Section 6 C Gears, Couplings III - Part 1 Page 6–4 GL 2012

* ρa0 = coefficient of tip radius of tool [–] 4.4 Face load distribution factors KHß and K Σ = shaft angle (bevel gears) [°] Fß The face load distribution factors take into account σ = root bending stress [N/mm2] F the effects of uneven load distribution over the tooth 2 σFE = root stress [N/mm ] flank on the contact stress (KHß) and on the root 2 stress (KFß). σFG = root stress limit [N/mm ] 2 In the case of flank corrections which have been de- σF0 = nominal root stress [N/mm ] termined by recognized calculation methods, the KHß σF lim = endurance limit for bending stress and KFß values can be preset. Hereby the special [N/mm2] influence of ship operation on the load distribution 2 has to be taken into account. σFP = permissible root stress [N/mm ] 2 σH = calculated contact stress [N/mm ] 4.5 Transverse load distribution factors KHα and K 2 Fα σHG = modified contact stress limit [N/mm ] The transverse load distribution factors K and K σ = endurance limit for contact stress [N/mm2] Hα Fα H lim take into account the effects of an uneven distribution 2 σHP = permissible contact stress [N/mm ] of force of several tooth pairs engaging at the same time. 2 σH0 = nominal contact stress [N/mm ] In the case of gears in main propulsion systems with a gear toothing quality described in 2.1.2. 3.3 The input data required to carry out load- bearing capacity calculations are summarized in KHα = KFα = 1,0 Table 6.2. can be applied. For other gears the transverse load distribution factors are to be calculated in accordance 4. Influence factors for load calculations with DIN/ISO explicitly quoted under 2.1.1 and 4.1 Rated torque 2.1.2.

The calculation of the rated torque has to be based on 5. Contact stress the planned maximum continuous rating.

5.1 The calculated contact stress σH shall not 4.2 Application factor KA exceed the permitted flank stress σHP (Hertzian flank The application factor KA takes into account the stress). increase in rated torque caused by superimposed σ =σ ⋅KKKK ⋅ γ ⋅⋅ ⋅ K ≤σ (1) dynamical or impact loads. KA is determined for HH0A vHHβα HP main and auxiliary systems in accordance with Table 6.3. Ft u1+ σH0 = σ=ZZZZ ⋅ ⋅⋅⋅ ⋅ H0 H E εβ db⋅ u 4.3 Load distribution factor Kγ 1

The load distribution factor Kγ takes into account 5.2 The permissible contact stress σHP shall deviations in load distribution, e.g. in gears with dual include a safety margin S as given in Table 6.1 or multiple load distribution or planetary gearing with H more than three planet wheels. against the contact stress limit σHG which is deter- mined from the material-dependent endurance limit The following values apply for planetary gearing: 3 σH lim as shown in Table 6.4 allowing for the influ- Gear with: ence factors ZNT, ZL, ZV, ZR, ZW, ZX. σ – up to 3 planet wheels Kγ = 1,0 HG σ=HP (2) SH – 4 planet wheels Kγ = 1,2 σHG = σHlim⋅⋅⋅⋅⋅⋅ZZZZZZ NT L V R W X – 5 planet wheels Kγ = 1,3

– 6 planet wheels Kγ = 1,6

In gears which have no load distribution Kγ = 1,0 is applied. –––––––––––––– The application of different factors Kγ may be agreed 3 With consent of GL for case hardened steel with proven if adequate evidence is submitted to GL. quality higher endurance limits may be accepted. III - Part 1 Section 6 C Gears, Couplings Chapter 2 GL 2012 Page 6–5

Table 6.2 List of input data for evaluating load-bearing capacity

Yard / Newbld No. Reg. No. Manufacturer Type Application Cylindrical gear Bevel gear 1 Nominal rated power P kW Ice class – No. of revolutions n1 1/min No. of planets – Application factor KA – Dynamic factor Kv – Load distribution K – K – Face load Hβ factor γ distribution K 1 – K – factors Hβ−be Transverse load Hα KFβ – distribution factors KFα – Geometrical data Pinion Wheel Tool data Pinion Wheel

Addendum 1 z – – x/xhm – Number of teeth modification coeff.

1 Normal modul mn/mnm mm – Thickness Mean normal modul m 1 mm 1 nm modification coeff. xsm – ° Coefficient of tool Normal press. angle α ρ * – n tip radius a0 Addendum coefficient Centre distance a mm h * – of tool a0 ° Dedendum coefficient Shaft angle 1 h * – ∑ of tool f0 Relative effective face Utilized dedendum b /b 1 – h * width eh coefficient of tool FfP0 – Helix angle β ° Protuberance pr mm 1 Mean helix angle β/β m ° Protuberance angle αpr ° Facewidth b mm Machining allowance q mm

Tip diameter da mm Measure at tool Bzo mm Backlash Root diameter dfe mm allowance/tolerance – Lubrication data Quality 2 kin. viscosity 40 °C ν40 mm /s Quality acc. to DIN Q – Mean peak to valley 2 R kin. viscosity 100 °C ν100 mm /s roughness of flank zH μm Mean peak to valley R μm Oil temperature ϑOil °C roughness of root zF Initial equivalent F μm FZG load stage – misalignment βx Material data Normal pitch error fpe μm Material type Profile form error ff μm Endurance limit for N/mm2 contact stress σH lim Date: Endurance limit for σ N/mm2 bending stress F lim

Surface hardness HV Signature: Core hardness HV Heat treatment – method 1 declaration for bevel gear

Chapter 2 Section 6 D Gears, Couplings III - Part 1 Page 6–6 GL 2012

Table 6.3 Application factors Table 6.5 Endurance limits 3 for tooth root bending stress σFE = σF lim ⋅ YST with YST = 2 System type KA * σFE = σF lim ⋅ YST Main system: Material [N/mm2] Turbines and electric drive sys- Case-hardened steels, case- 1,1 860 – 920 tems hardened Diesel engine drive systems with Nitriding steels, gas nitrided 850 fluid clutch between engine and 1,1 Alloyed heat treatable steel, bath 740 gears or gas nitrided Alloyed heat treatable steel, Diesel engine drive systems with 700 highly flexible coupling between 1,3 induction hardened engine and gears Alloyed heat treatable steels 0,8 HV10 + 400 Diesel engine drive systems with Unalloyed heat treatable steel 0,6 HV10 + 320 no flexible coupling between en- 1,5 Structural steel 0,8 HB + 180 Cast steel, cast iron with nodular gine and gears 0,8 HB + 140 Generator drives 1,5 graphite Auxiliary system: Note For alternating stressed toothing only 70 % of these Thruster with electric drive 1,1 (20 000 h) 1 values are permissible.

Thruster drives with diesel en- 1,3 (20 000 h) 1 gines 6. Tooth root bending stress 0,6 (300 h) 1 Windlasses 1 2,0 (20 h) 6.1 The calculated maximum root bending stress Combined anchor and mooring 0,6 (1000 h) 1 σF of the teeth shall not exceed the permissible root winches 2,0 (20 h) 2 stress σFP of the teeth. Note The tooth root stress is to be calculated separately for 1 Assumed operating hours pinion and wheel. 2 Assumed maximum load of windlasses For other types of system K is to be stipulated A σF = σF0 ⋅ KA ⋅ Kv ⋅ Kγ ⋅ KFβ ⋅ KFα ≤ σFP (3) separately.

Ft σF0 = ⋅ YYYFS⋅⋅β bm⋅ n Table 6.4 Endurance limits 4 for contact stress σH lim 6.2 The permissible root bending stress σFP shall have a safety margin SF as indicated in 2 Material σH lim [N/mm ] Table 6.1 against the root stress limit σFG which is determined from the material-dependent fatigue Case-hardening steels, case- 3 strength σFE or σF lim in accordance with Table 6.5 , hardened 1500 allowing for the stress correction factors YST, YNT, Nitriding steels, gas nitrided 1250 Yδ rel T, YR rel T, YX. Alloyed heat treatable steels, bath 850 – 1000 or gas nitrided σFG σ=FP (4) Alloyed heat treatable steels, 0,7 HV10 + 800 SF induction hardened Alloyed heat treatable steel 1,3 HV10 + 350 σFG = σFlim⋅⋅YY ST NT ⋅ Yδ relT ⋅ Y RrelT ⋅ Y X Unalloyed heat treatable steel 0,9 HV10 + 370 Structural steel 1,0 HB + 200 Cast steel, cast iron and nodular 1,0 HB + 150 cast graphite D. Gear Shafts

1. Minimum diameter –––––––––––––– The dimensions of shafts of reversing and reduction 4 With consent of GL for case hardened steel with or over proven quality application of higher values for fatigue gears are to be calculated by applying the following strength may be accepted. formula: III - Part 1 Section 6 E Gears, Couplings Chapter 2 GL 2012 Page 6–7

P E. Equipment dFk≥⋅ ⋅ Cw (5) ⎡⎤4 3 ⎛⎞di 1. Gear lubrication n1⋅−⎢⎥⎜⎟ ⎢⎥⎝⎠da ⎣⎦ 1.1 General The gear system has to be designed to enable a start d with a lubrication oil temperature from 0 °C upwards for i ≤ 0, 4 the expression without restrictions. da For engageable couplings the guidelines according to 4 ⎡⎤⎛⎞d G.5. are valid. ⎢⎥1 − ⎜⎟i may be set to 1,0 ⎢⎥d Suitable equipment has to be provided, which limits ⎣⎦⎝⎠a the water content in the gear lubricant and the humid- ity within the gear in a way to exclude corrosion in d = required outside diameter of shaft [mm] the gear.

1.2 Oil level indicator di = diameter of shaft bore for hollow shafts [mm] For monitoring the lubricating oil level in main and auxiliary gears, equipment is to be fitted to enable the oil level to be determined. da = actual shaft diameter [mm] 1.3 Pressure and temperature control P = driving power of shaft [kW] Temperature and pressure gauges are to be fitted to n = shaft speed [min-1] monitor the lubricating oil pressure and the lubricat- ing oil temperature at the oil-cooler outlet before it enters the gears. F = factor for the type of drive [–] Plain journal bearings are also to be fitted with tem- = 95 for turbine plants, electrical drives and perature indicators. engines with slip couplings Where gears are fitted with anti-friction bearings, a temperature indicator is to be mounted at a suitable = 100 for all other types of drive. GL reserves point. For gears rated up to 2 000 kW, special ar- the right to specify higher F values if this rangements may be agreed with GL. appears necessary in view of the loading of the plant. Where ships are equipped with automated machinery, the requirements of the GL Rules for Automation (III-1-3b) are to be complied with. Cw = material factor 1.4 Lubricating oil pumps 500 = Lubricating oil pumps driven by the gearing are to be Rm + 160 mounted in such a way that they are accessible and can be replaced easily by using common board avail- able tools. Rm = tensile strength of the shaft material The supply of lubricating oil has to be ensured by a For wheel shafts no higher value than 800 main pump and an independent stand by pump. If a N/mm2 shall be used. For pinion shafts the reduction gear is approved for sufficient self lubrica- actual tensile strength may generally be sub- tion at 75 % of the driving torque, the stand by pump stituted for Rm. may be abolished up to a performance relation P/n1 [kW/min-1] ≤ 3,0. k = 1,10 in general For the pumps to be assigned see the GL Rules for Ship Operation Installations and Auxiliary Systems = 1,15 in the area of the pinion or wheel body (III-1-4), Section 8, I.3 if this is keyed to the shaft and for multiple- spline shafts 2. Equipment for operation, control and safety Higher values of k may be specified by GL where increased bending stresses in the shaft Equipment for operation and control has to enable a are expected because of the bearing ar- safe operation of the gear by remote control as well rangement, the casing design, the tooth pres- as directly at the gear. All parameters which are im- sure, etc. portant for a regular operation are to be indicated Chapter 2 Section 6 F Gears, Couplings III - Part 1 Page 6–8 GL 2012

directly at the gear. These indicating instruments shall 2. Testing be put together in an auxiliary control stand, as far as possible. 2.1 Testing in the manufacturer's works When the testing of materials and component tests 3. Gear casings have been carried out, gearing systems for the main propulsion plant and for essential auxiliaries in ac- The casings of gears belonging to the main propul- cordance with Section 1, B.4. are to be presented to sion plant and to essential auxiliaries are to be fitted GL for final inspection and operational testing in the with removable inspection covers to enable the tooth- manufacturer's works. For the inspection of welded ing to be inspected, the thrust bearing clearance to be gear casings, see the GL Rules for Welding in the measured and the oil sump to be cleaned. Various Fields of Application (II-3-3).

4. Seating of gears The final inspection is to be combined with a trial run lasting several hours under part or full-load condi- It has to be taken care that no inadmissible forces tions, on which occasion the tooth clearance and caused by deformation of the foundation as part of contact pattern are to be checked. In the case of a trial the hull structure are transferred to the toothing. at full-load, any necessary running-in of the gears must have been completed beforehand. Where no test The seating of gears on steel or cast resin chocks is to facilities are available for the operational and on-load conform to the GL Guidelines for the Seating of testing of large gear trains, these tests may also be Propulsion Plants and Auxiliary Machinery (VI-4-3). performed on board ship on the occasion of the dock trials. For the seating of gears on casting resin chocks the thrust has to be absorbed by means of stoppers. The Tightness tests are to be performed on those compo- same applies for casting resin foundations of separate nents to which such testing is appropriate. thrust bearings. Reductions in the scope of the tests require the con- sent of GL.

2.2 Tests during sea trials F. Balancing and Testing 2.2.1 Prior to the start of sea trials, the teeth of the 1. Balancing quality gears belonging to the main propulsion plant are to be coloured with suitable dye to enable the check of the contact pattern. During the sea trials, the gears are to 1.1 Gear wheels, pinions, shafts, couplings and, be checked at all forward and reverse speeds to estab- where applicable, high-speed flexible couplings are lish their operational efficiency and smooth running to be assembled in a properly balanced condition. as well as the bearing temperatures and the pureness of the lubricating oil. At the latest on conclusion of 1.2 The generally permissible residual imbal- the sea trials, the gearing is to be examined via the ance U per balancing plane of gears for which static inspection openings and the contact pattern checked. or dynamic balancing is rendered necessary by the If possible the contact pattern should be checked after method of manufacture and by the operating and conclusion of every load step. Assessment of the loading conditions can be determined by applying the contact pattern is to be based on the guide values for formula the proportional area of contact in the axial and radial directions of the teeth given in Table 6.6 and shall 9,6⋅⋅ O G take account of the running time and loading of the U[kgmm]= ( 6 ) ()zn⋅ gears during the sea trial.

G = mass of component to be balanced [kg] 2.2.2 In the case of multistage gear trains and planetary gears manufactured to a proven high degree n = operating speed of component to be balanced of accuracy and if an appropriate check at the manu- -1 facturer’s workshop was successful, checking of the [min ] contact pattern after sea trials may, with the consent z = number of balancing planes [–] of GL, be reduced in scope. Q = degree of balance [–] 2.2.3 For checking of gears of Z-drives, e.g. rud- – 6,3 for gear shafts, pinion and coupling der propellers and azimuth propulsors, as main pro- members for engine gears pulsion see Section 7b, D.8.

– 2,5 for torsion shafts and gear couplings, 2.2.4 Further requirements for the sea trials are pinions and gear wheels belonging to tur- contained in the GL Guidelines for Sea Trials of bine transmissions Motor Vessels (VI-11-3) III - Part 1 Section 6 G Gears, Couplings Chapter 2 GL 2012 Page 6–9

Table 6.6 Percentage area of contact n = speed in rev/min [min–1] 2 Material, Working tooth Width of tooth pzul = 0,7 . ReH for ductile steels [N/mm ] manufacturing 2 depth (without (without end pzul = 0,7 . Rm for brittle steels [N/mm ] of toothing tip relief) relief) σ = permissible Hertzian stress [N/mm2] heat-treated, HP milled, 33 % average Where methods of calculation recognized by GL are shaped 70 % used for determining the Hertzian stress on the flanks of tooth couplings with convex tooth flanks, the per- surface- missible Hertzian stresses are equal to 75 % of the hardened, 80 % values of σ shown in C.5.2 with influence factors grinded, 40 % average HP scarped ZNT to ZX set to 1,0: 2 pzul = 400 – 600 N/mm 2.3 Acoustic properties to be proven in compli- for tooth systems of quenched and tempered ance with the GL Rules for Hull Structures and Ship steel; the higher values apply to high tensile Equipment (III-1-1), Section 16, B.3. steels with superior tooth manufacturing and surface finish quality = 800 – 1000 N/mm2 G. Design and Construction of Couplings for toothing made of hardened steel (case or nitrogen). Higher values apply for superior 1. It shall be possible to disengage respectively tooth manufacturing and surface finish qual- to install and dismantle all couplings outside of gears ity using the tooling on board without displacing of major system's components such as gear, thrust bear- 3.3 The coupling teeth are to be effectively ing, engine, etc. lubricated. For this purpose a permanent oil or grease lubrication in the coupling may generally be regarded as adequate where 2. Flange and clamp-type couplings In the dimensional design of the coupling bodies, d ⋅ n2 < 6 ⋅ 109 [mm/min2] (8) flanges and bolts of flange and clamp-type couplings, the Rules specified in Section 5 are to be complied For higher values of d ⋅ n2, couplings in main propul- with. sion plants are to be provided with a circulating lu- brication oil system. 3. Tooth couplings 3.4 For the dimensional design of the sleeves, 3.1 Torsionally stiff couplings, such as multi- flanges and bolts of gear couplings the formulae tooth couplings may be used to compensate devia- given in Section 5 are to be applied. tions in radial and axial direction. 4. Flexible couplings 3.2 Adequate loading capacity of the tooth flanks of straight-flanked tooth couplings requires 4.1 Scope that the following conditions are satisfied: Flexible couplings shall be approved for the loads 2,55⋅⋅⋅ 107 P K specified by the manufacturer and for use in main p =≤A p (7) bhdzn⋅⋅⋅⋅ zul propulsion plants and essential auxiliary machinery. In general flexible couplings shall be type-approved. p = actual contact pressure of the tooth flanks Detailed requirements for type approvals of flexible [N/mm2] couplings are defined in the GL Guidelines Test Requirements for Components and Systems of Me- P = driving power at coupling [kW] chanical Engineering and Offshore Technology (VI- d = standard pitch diameter [mm] 7-8), Section 3.

KA = application factor in accordance with C.4.2 4.2 Documentation [–] The documentation to be submitted shall include: h = working depth of toothing [mm] – assembly drawings b = load-bearing tooth width [mm] – detailed drawings including material character- z = number of teeth [–] istics Chapter 2 Section 6 G Gears, Couplings III - Part 1 Page 6–10 GL 2012

– definition of main parameters Table 6.7 Limits of shear stress – rubber Shore hardness Shore hardness Limit of shear stress [ – ] [N/mm2] – nominal torque TKN 40 0,4 – permissible torque TKmax1 for normal tran- 50 0,5 sient conditions like starts/stops, passing 60 0,6 through resonances, electrical or mechani- 70 0,7

cal engagements, ice impacts, etc.

– permissible torque TKmax2 for abnormal For special materials, e.g. silicon, corresponding limit impact loads like short circuits, emergency values shall be derived by experiments and experi- stops, etc. ences.

– permissible vibratory torque ± TKW for 4.4.4 Flexible couplings in the main propulsion continuous operation plant and in power-generating plants shall be so di- mensioned that they are able to withstand for a rea- – permissible power loss P due to heat KV sonable time operation with any one engine cylinder dissipation out of service, see Section 8, C.4.2. Additional dy- – permissible rotational speed nmax namic loads for ships with ice class are to be taken into account according to Section 9. – dynamic torsional stiffness cTdyn, radial stiffness crdyn 4.4.5 If a flexible coupling is so designed that it exerts an axial thrust on the coupled members of the – relative damping ψ respectively damping driving mechanism, provision shall be made for the characteristics absorption of this thrust. – permissible axial, radial and angular dis- If torsional limit devices are applicable, the function- placement ality shall be verified. – permissible permanent twist 4.4.6 Flexible couplings for diesel generator sets – design calculations shall be capable of absorbing impact moments due to electrical short circuits up to a value of 6 times the – test reports nominal torque of the plant. 4.3 Tests 5. Clutches The specifications mentioned in 4.2 are to be proven and documented by adequate measurements at test 5.1 General establishments. The test requirements are included in the GL Guidelines Test Requirements for Compo- 5.1.1 Definition and application nents and Systems of Mechanical Engineering and Offshore Technology (VI-7-8), Section 3. Clutches are couplings which can be engaged and disengaged mechanically, hydraulically or pneumati- For single approvals the scope of tests may be re- cally. The following requirements apply for their use duced by agreement with GL. in shaft lines and as integrated part of gear boxes. Clutches intended for trolling operation are subject to 4.4 Design special consideration.

4.4.1 With regard to casings, flanges and bolts the 5.1.2 Documentation requirements specified in Section 5, D. are to be For all new types of clutches a complete documenta- complied with. tion has to be submitted to GL for approval in tripli- 4.4.2 The flexible element of rubber couplings cate. This documentation has to include e.g.: shall be so designed that the average shear stress in – assembly drawings the rubber/metal bonding surface relating to TKN does not exceed a value of 0,5 N/mm2. – detail drawings of torque transmitting compo- nents including material properties 4.4.3 For the shear stress within the rubber ele- – documentation of the related system for engag- ment due to TKN it is recommended not to exceed a ing/disengaging value subjected to the Shore hardness according to Table 6.7. – definition of the following main technical pa- rameters Higher values can be accepted if appropriate strengths of rubber materials have been documented – maximum and minimum working pressure by means of relevant tests and calculations. for hydraulic or pneumatic systems [bar] III - Part 1 Section 6 G Gears, Couplings Chapter 2 GL 2012 Page 6–11

– static and dynamic friction torque [kNm] 5.3.5 Controls and alarms – time diagram for clutching procedure Local operation of remotely controlled clutches for the propulsion plants shall be possible. – operating manual with definition of the The pressure of the clutch activating medium has to permissible switching frequency be indicated locally. Alarms according to the GL – for special cases calculation of heat balance, if Rules for Automation (III-1-3b), Section 9, E. have to requested by GL be provided.

5.4 Tests 5.2 Materials The mechanical characteristics of materials used for 5.4.1 Tests at the manufacturer’s works the elements of the clutch shall conform to the GL Magnetic particle or dye penetrant inspection shall be Rules II – Materials and Welding. applied for crack detection at surface hardened zones with increased stress level as well as at shrinkage 5.3 Design requirements surfaces. The manufacturer shall issue a Manufac- turer Inspection Certificate. 5.3.1 Safety factors Clutches for ship propulsion plants, for generator sets and transverse thrusters are to be presented to GL for For the connections to the shafts on both sides of the final inspection and, where appropriate, for the per- clutch and all torque transmitting parts the require- formance of functional and tightness tests. ments of Section 5 have to be considered. If a type approval is requested the requirements will The mechanical part of the clutch may be of multiple be defined on a case by case basis by GL Head Of- disc type. The multiple disc package shall be kept fice. free of external axial forces. All components shall be designed for static loads with a friction safety factor 5.4.2 Tests on board between 1,8 and 2,5 in relation to the nominal torque of the driving plant. As part of the sea trials the installed clutches will be tested for correct functioning on board in presence of A dynamic switchable torque during engaging of 1,3 a GL Surveyor, see also the GL Guidelines for Sea times the nominal torque of the driving plant has Trials of Motor Vessels (VI-11-3). generally to be considered. In case of combined mul- tiple engine plants the actual torque requirements will 6. Hydraulic couplings/Torque converters be specially considered. The torque characteristic of the hydraulic coupling has to be adjusted to the operating conditions. As 5.3.2 Ice class hydraulic oil the lubricating oil required for the diesel For clutches used for the propulsion of ships with ice engines or the gears shall be used. class the reinforcements according to Section 9 have A timely unlimited operation of the drive machines to be considered. with empty coupling is to be guaranteed for the whole speed range. The actual operation condition 5.3.3 Measures for a controlled switching of the has to be indicated (for this see also Section 2). coupling and an adequate cooling in all working conditions have to be provided. 7. Mechanical clutches for multi-engine synchronization 5.3.4 Auxiliary systems for engaging/ disengag- ing 7.1 Basic description If hydraulic or pneumatic systems are used to engage/ For propulsion plants driven by multiple power disengage a clutch within the propulsion system of a sources of different type (such as diesel engines and ship with a single propulsion plant an emergency turbines) generally a switching over to alternative operation shall be possible. This may be done by a operational modes without intermediate shut-down or redundant power system for engagement/ disengage- reduction of the speed of the driving engine may be ment or in a mechanical way, e.g. by installing con- required. For such purposes a synchronisation of the necting bolts. For built-in clutches this would mean speed of the engines in duty and the idling engine that normally the connecting bolts shall be installed should take place before introduction of mechanical on the side of the driving plant equipped with turning clutch in procedure. facilities. The synchronisation aims to minimise the clutch in The procedure to establish emergency service has to shock and induced peak torques, but also to enable an be described in the operating manual of the clutch undisturbed and smooth continuous operation while and has to be executed in a reasonable time. changing the operational mode. The speed difference Chapter 2 Section 6 G Gears, Couplings III - Part 1 Page 6–12 GL 2012

before introduction of clutch in procedure should not should be set in a way that the slip point is reached be more than 10 %, or depending on the moment of for torque values between 150 % and 250 % of the inertias of the driving and driven parts the transient nominal torque, depending on the requirements of the speed drop or increase after clutch in should be less manufacturer. than 5 %. Additional functions, like lock-in/lock-out control or position indication may be required depending on the 7.2 Design requirements overall design of the propulsion plant. The mechanical part of the clutch may be of multiple disc or mechanical teeth type. All components shall 8. Testing be designed for the nominal transmitted torque with a Couplings for ship propulsion plants and couplings safety factor of 2,5. In case that the speed is not syn- for generator sets and transverse thrusters are to be chronised in accordance to 7.1 a safety factor of 3,5 presented to GL for final inspection and, where ap- must be reckoned with. In case that multiple disc propriate, for the performance of functional and plates or other frictional devices are applied, they tightness tests. III - Part 1 Section 7a A Propulsors Chapter 2 GL 2012 Page 7a–1

Section 7a

Propulsors

A. General requirements in the building specification, e.g. mini- mum circumferential speed, etc. Nominal speed ahead 1. Scope and propeller diameter are to be selected for a maxi- mum ship speed without cavitation. The limit curve These Rules apply to screw propellers (controllable for cavitation noise in the SIGMAn - CTh diagram in J. and fixed pitch) as well as miscellaneous propulsion may be used. The noise emission from the propeller systems. See Section 9 for information on propeller shall be estimated already in the concept phase. sizes and materials for ships navigating in ice. 3.3 Noise behaviour 2. Documents for approval 3.3.1 Cavitation noise 2.1 Design drawings of propellers in main pro- pulsion systems having an engine output in excess of The propeller has to be designed to develop low noise, 300 kW and in transverse thrust systems of over especially at the nominal acoustic operation point. 500 kW, are to be submitted to GL for approval. The Cavitation noise has to be avoided. drawings are required to contain all the details neces- sary to carry out an examination in accordance with Note the following requirements. To facilitate a smooth and efficient approval process they should be submitted Guiding values for cavitation avoidance are contained electronically via GLOBE 1. In specific cases and in J. following prior agreement with GL they can also be submitted in paper form in triplicate. 3.3.2 Singing behaviour By calculating the natural frequencies of the propeller 2.2 In the case of controllable pitch propeller and by a comparison with the hydrodynamic excita- systems, general and sectional drawings of the com- tion at the trailing edges the risk of singing of the plete controllable pitch propeller system are to be propeller has to be estimated and minimised. If sing- submitted in addition to the design drawings for blade, ing is observed during trials, relevant counter meas- boss and pitch control mechanisms. Control and hy- ures have to be applied. draulic diagrams are to be submitted. In the case of new designs or controllable pitch propeller systems Note which are being installed for the first time on a ship with GL Class, a description of the controllable pitch The singing of a propeller is a strong peak tone in the propeller system has also to be submitted. noise spectrum. It is created by the excitation of natu- ral frequencies as a consequence of vortex shedding at 3. Design the trailing edge.

3.1 Propellers are to be designed in a way that 3.3.3 Air blow-out device their power consumption lies within the family of 3.3.3.1 Blow-out devices for air may be considered characteristics of the driving machinery. for naval ships for which low-noise operation is re- – The propeller of controllable pitch plants shall quired in velocity ranges with cavitating propeller. If absorb the continuous rating of the driving ma- an air blow-out device is required in the building chinery at nominal speed. specification, the system has to be agreed with the Naval Administration and GL. The details of the de- – A fixed pitch propeller shall reach the absorbed sign have to be included in the building specification. power/speed relation defined in the building specification. 3.3.3.2 The exits of the blown-out air have to be arranged in a way that a compact air veil covers the 3.2 For determination of the propeller parameters blade surface. The feed of the air into the propulsion well known and established methods may be used. system should be done at the front end of the propeller The lay out of the propeller has to consider the noise shaft. The air temperature at the shaft entrance should not be higher than 40 °C. By special measures in the –––––––––––––– construction it has to be secured that no air penetrates 1 Detailed information about GLOBE submission can be found into the hydraulic system. On the other hand no oil or on GL’s website www.gl-group.com/globe. water shall get into the air system. Chapter 2 Section 7a B Propulsors III - Part 1 Page 7a–2 GL 2012

3.3.3.3 For the creation of an effective air veil at the their parameters may be taken from the GL Rules for propeller blade the required air volume is depending Metallic Materials (II-1). on the propeller speed. Therefore speed regulated air compressors have to be provided. Metallic propellers are to be made of sea-water- resistant copper cast alloys or steel cast alloys with a 2 3.3.3.4 All components and pipes of the air system minimum tensile strength Rm of 440 N/mm . have to be made of stainless steel. For the purpose of the following design Rules govern- 3.3.3.5 For ships with NBC protection the air should ing the thickness of the propeller blades, the requisite be sucked from outside of the citadel. Ventilation and resistance to seawater of a cast copper alloy or cast drainage pipes shall be conducted in closed form to steel alloy is considered to be achieved if the alloy can the outside. withstand a fatigue test under alternating bending stresses comprising 108 load cycles amounting to 3.3.4 Measurements of water-borne noise about 20 % of the minimum tensile strength and car- ried out in a 3 % NaCl solution, and provided that the 3.3.4.1 The measurements of water-borne noise have fatigue strength under alternating bending stresses in to be executed in deep and shallow water according to natural seawater can be proven to be not less than the building specification. about 65 % of the values established in 3 % NaCl solution. Sufficient fatigue strength under alternating 3.3.4.2 For the assessment of cavitation noise the bending stresses has to be proven by a method recog- following test criteria will be applied simultaneously: nized by GL. – recording audible noise in the frequency range 30 Hz – 20 kHz 2. Components for controllable pitch and assembled fixed pitch propellers – comparative evaluation of the relevant third filter analyses. Checking if a clear increase of The materials of the major components of the pitch noise level in the complete frequency range control mechanism and also the blade and boss retain- above 1 kHz is to be observed or if with in- ing bolts have to comply with the GL Rules for Metal- creased speed a transfer of the noise peak to the lic Materials (II-1). range of 100 Hz is happening The blade retaining bolts of assembled fixed pitch – creation of a DEMON ("Demolition of Envelop propellers or controllable pitch propellers are to be Modulation on Noise") spectrum made of seawater-resistant materials so far they are not protected against contact with seawater. – measurement of the target level with a linear antenna 3. Material parameters 3.3.4.3 The execution of the measurements and the documentation of results has to be coordinated with The material has to be documented according to the GL. GL Rules for Materials for Propeller Fabrication (II-1- 5), Section 1, K. 3.4 Corrosion protection If materials shall be used which are not corresponding to the GL grades, the following parameters have to be The propeller has to be protected against electro- delivered to GL: chemical corrosion according to the GL Rules for Hull Structures (I-1-1), Section 35. – designation of the material (acronym) – chemical composition 4. Designation – tensile strength, yield stress and elongation of a Each propeller and the essential components for material sample (serves especially for the identi- torque transmission and for blade adjustment of con- fication of the material) trollable pitch propellers respectively have to be defi- nitely marked with the appropriate steel-stamp. The – impact energy, if required markings have to be executed by steel-stamp numbers – bending fatigue strength in sea water spray fog with rounded edges to avoid notch effects. (serves as limit value for the strength calcula- tions) – density of material, modulus of elasticity, ther- mal expansion coefficient B. Materials – magnetic characteristics, if applicable 1. Propellers and propeller hubs – information concerning repairing ability (weld- ability, heat treatment) The material for the propulsion device has to be se- lected according to the actual functional requirements. – information concerning resistance against corro- Special materials are not prescribed. Materials and sion and erosion III - Part 1 Section 7a C Propulsors Chapter 2 GL 2012 Page 7a–3

4. Novel materials Table 7a.1 Characteristic values Cw

Where propeller materials with not sufficient experi- Material Description 1 C ence for their reliability are applied, the suitability has w to be proven particularly to GL. Cu 1 Cast manganese brass 440 Cu 2 Cast manganese nickel brass 440 5. Material testing Cu 3 Cast nickel aluminium bronze 590 The material of propellers, propeller bosses and all Cast manganese aluminium essential components involved in the transmission of Cu 4 630 torque and pitch setting is to be tested in accordance bronze with the GL Rules for Metallic Materials (II-1). This Martensitic cast chrome also applies to components which are used to control Fe 3 660 steel 13/1-6 the blades and also to propellers in main propulsion systems smaller than 300 kW power and transverse Martensitic-austenitic cast Fe 4 600 thrust systems of less than 500 kW power. steel 17/4 Fe 5 Ferritic-austenitic cast steel 600 24/8

C. Design and Dimensioning of Propellers Fe 6 Austenitic cast steel 17/8-11 500 1 for the chemical composition of the alloys, see GL Rules Alternative design methods which guarantee the same II –Materials and Welding sufficient safety may be submitted to GL for approval.

1. Symbols and terms CTh = thrust load coefficient

A = effective area of a shrink fit [mm2] T = 0,5⋅ρ⋅ v2 ⋅ A 2 AD AD = propeller plane area [m ] d = pitch circle diameter of blade or propeller- B = developed blade width of cylindrical sec- fastening bolts [mm] tions at radii 0,25 R, 0,35 R and 0,6 R [mm] in an expanded view di = diameter of shaft bore [mm]

dk = root diameter of blade or propellerfastening cA = coefficient for shrunk joints [–] bolts [mm]

= 1,0 for geared diesel engine and turbine D = diameter of propeller [mm] plants as well as for electric motor drives = 2 ⋅ R = 1,2 for direct diesel engine drives dm = mean taper diameter [mm] CG = size factor in accordance with formula (2) [–] DN = mean outer diameter of propeller hub [mm] e = blade rake acc. Fig. 7a.1 [mm] CDyn = dynamic factor in accordance with formula (3) [–] = R ⋅ tan ε

Cw = characteristic value for propeller material EN = modulus of elasticity for hub material 2 as shown in Table 7a.1 corresponds to the [N/mm ] minimum tensile strength Rm of the propel- EW = modulus of elasticity for shaft material ler material where sufficient fatigue [N/mm2] strength under alternating bending stresses according to B.1. is proven [-] ET = thrust stimulating factor in accordance with formula (5) [–] C = conicity of shaft ends [–] f, f1, f2 = factors in formulae (2), (4) and (11) [–] difference in taper diameter = H = pressure side pitch of propeller blade at length of taper radii 0,25 R, 0,35 R and 0,6 R [mm] Chapter 2 Section 7a C Propulsors III - Part 1 Page 7a–4 GL 2012

Hm = mean effective pressure side pitch for pitch pL = local pressure at the propeller blade varying with the radius [mm] surface [N/mm2]

∑⋅⋅(R B H) pS = static pressure at propeller axis of rota- = 2 ∑⋅(R B) tion [N/mm ] 2 R, B and H are the corresponding measures pV = vapour pressure [N/mm ] of the various sections PW = nominal power of driving engine at k = coefficient for various profile shapes in MCR [kW] accordance with Table 7a.2 [–] Q = peripheral force at mean taper diameter [N] Table 7a.2 Values of k for examples of various profile shapes Rp 0,2 = 0,2 % proof stress of propeller material [N/mm2] Values of k Profile shape ReH = minimum nominal upper yield strength 0,25 R 0,35 R 0,6 R [N/mm2] Segmental profiles 2 73 62 44 Rm = tensile strength [N/mm ] with circular arced suction side r = fillet radius [mm] S = margin of safety against propeller slip- ping on cone Segmental profiles 77 66 47 with parabolic = 2,8 [–] suction side SIGMAn = cavitation inception number [–]

t = maximum blade thickness of developed cylindrical section at radii 0,25 R Blade profiles as (t0,25), 0,35 R (t0,35), 0,6 R (t0,6) and for Wageningen B 80 66 44 1,0 R (t1,0) [mm] Series propellers T = propeller thrust [N]

TM = impact moment [Nm]

vA = average water velocity to the propeller [m/s]

vS = speed of ship at MCR [kn] w = wake fraction [–] KN = diameter ratio of hub [–] = dm/DN W = section modulus of cylindrical blade K = diameter ratio of shaft [–] = d /d 0,35R W i m section at radius 0,35 R [mm3] L = pull-up length of propeller on cone [mm] W0,60R = section modulus of cylindrical blade 3 Lact = chosen pull-up distance [mm] section at radius 0,60 R [mm ]

LM = ⅔ of the leading-edge part of the blade Wx = section modulus of cylindrical section width at 0,9 R, but at least ¼ of the total at the radius x [mm3] blade width at 0,9 R for propellers with high skew blades [mm] Z = total number of bolts used to retain one blade or propeller [–] L = pull-up length [mm] at t = 35 °C mech z = number of blades [–] L = temperature-related portion of pull-up temp α = pitch angle of profile at radii 0,25 R, length [mm] at t < 35 °C 0,35 R and 0,6 R [–] n2 = rotational speed of propeller at MCR 1, 27⋅ H [min-1] = α=arc tan 0,25 D p = surface pressure in the shrink joint between 0,91⋅ H propeller and shaft [N/mm2] = α=arc tan 0,35 D pact = surface pressure in the shrink joint at Lact 0,53⋅ H [N/mm2] = α=arc tan 0,6 D III - Part 1 Section 7a C Propulsors Chapter 2 GL 2012 Page 7a–5

αA = tightening factor for retaining bolts de- C = pending on the method of tightening used 2 (see VDI 2230 or equivalent standards [–] µo = coefficient of static friction [–] Guidance values: = 0,13 for hydraulic oil shrunk joints = 1,2 for angle control = 0,15 for dry fitted shrink joints = 1,3 for bolt elongation control bronze/steel = 0,18 for dry shrunk joints steel/steel = 1,6 for torque control νN = Poisson’s ratio of hub material [–] αN = coefficient of linear thermal expansion of hub material [1/°C] νW = Poisson’s ratio of shaft material [–] ψ = skew angle acc. to Fig. 7a.1 [°] αW = coefficient of linear thermal expansion of shaft material [1/°C] ρ = density of water [kg/m3]

ε = angle between lines of face generatrix and σmax/σm = ratio of maximum to mean stress at normal [–] pressure side of blades [–] 2 Θ = half-conicity of shaft ends [–] σV = von Mises equivalent stress [N/mm ]

e max. t 1,0 1,0 R thickness line

(+) (-) 0,9 R

0,8 R mid chord line

curve of 0,7 R swept area t 0,6 0,6 R

B0,6 0,5 R y 0,4 R D

t 0,25 r 0,25 R r 0,2 R B0,25

trailing edge leading edge

Blade-sections according to e Wageningen B-series

Fig. 7a.1 Illustration of blade geometry Chapter 2 Section 7a C Propulsors III - Part 1 Page 7a–6 GL 2012

2. Calculation of blade thickness 3 −9 vn(1w)DS2⋅⋅−⋅ ET ≈ 4,3⋅ 10 (5) T 2.1 At radii 0,25 R (t0,25) and 0,6 R (t0,6), the blade thicknesses of solid propellers have at least to f2 = 0,4 − 0,6 for single-screw ships, the lower comply with the formula (1): value applies to stern shapes with a big pro- peller tip clearance and no rudder heel, the t = Ko ⋅ k ⋅ K1 ⋅ CG ⋅ CDyn (1) larger value to sterns with small clearance and with rudder heel. Intermediate values are ecos⋅αn2 to be selected accordingly Ko = 1 ++ H 15000 = 0,2 for twin-screw ships k = as in Table 7a.2 = k' for other profiles as defined in Table 7a.2 2.2 The blade thicknesses of controllable pitch propellers are to be determined at radii 0,35 ⋅ R and β k' = k ⋅ x 0,6 ⋅ R by applying formula (1). βx ' For ships other than tugs, trawlers, etc. the diame-

βx = factor for the section modulus of the cylin- ter/pitch ratio D/Hm applicable to open-water naviga- drical section related to the pitch line of the tion at maximum engine power (MCR = Maximum blade for profile shapes defined in Table Continuous Rating) can be used in formula (1). 7a.2 2.3 The blade thicknesses calculated by apply- βx' = factor for the section modulus of the cylin- ing formula (1) represent the lowest acceptable val- drical section related to the pitch line of the ues for the finish-machined propellers. blade for profile shapes other than defined in Table 7a.2 2.4 The fillet radii at the transition from the W pressure and suction side of the blades to the propel- = x 2 ler boss shall correspond, in the case of three and tB⋅ four-bladed propellers, to about 3,5 % of the propel- ler diameter. For propellers with a larger number of ⎛⎞D blades the maximum possible fillet radii allowed by P102⋅⋅⋅5 ⋅α+α cossin w ⎜⎟the propeller design shall be aimed at, but these shall ⎝⎠Hm K = not be chosen less than 40 % of the blade root thick- 1 2 nBzCcos2w⋅⋅⋅⋅ε ness.

C = size factor [–] Variable fillet radii which are aiming at a uniform G stress distribution, may be applied if an adequate proof of stress is given case by case. The resulting D f1 + calculated maximum stress shall not exceed the val- = 1,1≥≥1000 0, 85 (2) ues occurring from a design with constant fillet radius 12,2 in accordance with the first paragraph of 2.4. f1 = 7,2 for solid propellers 2.5 For special designs such as propellers with = 6,2 for separately casted blades of variable skew angle ψ ≥ 25°, tip fin propellers, special profiles pitch or built-up propellers etc, a special mechanical strength calculation is to be submitted to GL. C = dynamic load factor [–] Dyn For re-calculation of the blade stress of these special propeller designs a blade geometry data file and de- ()σ / σ − 0,8 = max m ≥ 1,0 (3) tails on the measured wake field are to be submitted 0,7 to GL e-mail: [email protected], together with the design documentation. This file should be sent in plain text format. Supplementary information on the σmax for > 1, 5 , otherwise CDyn = 1,0 Classification of special designs can be requested by σm GL. σ /σ is generally to be taken from the detailed max m 2.6 If the propeller is subjected to an essential calculation according to 2.5. If, in exceptional cases, wear, e.g. by abrasion in tidal flats or rivers, a wear no such calculation exists, the stress ratio may be addition has to be provided to the thickness deter- calculated approximately according to formula (4). mined under 2.1 to achieve an equivalent life time. If the actual thickness in service drops below 50 % at σmax = f2 ⋅ ET + 1 with (4) the blade tip or 90 % at other radii of the rule thick- σm ness obtained from 2.1, effective counter measures III - Part 1 Section 7a D Propulsors Chapter 2 GL 2012 Page 7a–7

have to be taken. For unconventional blade geome- 3. Emergency control tries as defined in 2.5, the design thickness as shown on the approved drawings replaces the thickness 3.1 Controllable pitch propeller plants are to be requested according to 2.1. equipped with means for emergency control to main- tain the function of the controllable pitch propeller in case of failure of the remote control system. It is recommended to provide a device enabling the pro- peller blades to be locked in the “ahead” setting posi- D. Controllable Pitch Propellers tion.

1. General This pitch has to be selected in a way that a start of the propulsion system is possible with the weakest For multi-shaft propulsion plants separated hydraulic driving machinery and at a standstill of the ship. systems have to be provided for each controllable Afterwards it shall be possible to operate the system pitch propeller. like a fixed pitch propeller.

2. Design 3.2 Suitable devices have to prevent that an alteration of the blade pitch setting can lead to an For the design of the components, the following as- overload or stall of the propulsion engine. pects have to be considered. It has to be ensured that, in the event of failure of the 2.1 The adjustment of the controllable pitch control system, the setting of the blades propeller has to be done in a way that at a position – does not change, or "zero" of the operating lever and minimum operation – drifts to a final position slowly enough to allow speed, zero thrust is developed. If deviations because the emergency control system to be put into of adjustment tolerances are occurring, only thrust operation ahead shall be created. 4. Hydraulic control equipment Note The maximum adjustable pitch ahead should be at 4.1 Where the pitch-control mechanism is oper- least 108 % of the design pitch [mm], the maximum ated hydraulically, two mutually independent, power pitch astern should be at least 70 % of the design driven pump sets are to be installed. For propulsion pitch [mm]. plants up to 200 kW, one power-driven pump set is sufficient provided that, in addition, a hand-operated 2.2 The construction of controllable pitch pro- pump is provided, capable to control the blade pitch peller plants has to be flood safe, if required in the and being able to move the blades from ahead to the building specification. astern position in a sufficiently short time for save manoeuvring. 2.3 The installation and the dismantling of the The selection and arrangement of filters has to ensure controllable pitch propellers shall be possible without an uninterrupted supply with filtered oil, also during axial displacement of the shafts. The leading edge of filter cleaning or exchange. In general, main filters the blade shall lead without overhang to the blade are to be arranged on the pressure side directly after root disc. the pump. An additional coarse filtration of the hy- draulic oil at the suction side, before the pump, 2.4 The hub shall be tightened reliably. The should be provided. space before the blade gaskets shall stay under con- For all operating conditions the adjusting time be- stant pressure to avoid pressure and volume varia- tween design pitch and maximum astern pitch shall tions at the gaskets during pitch variation. A device be defined in building specification. Guidance values has to be provided which allows flushing of the hub are: content at the floating ship. The blade position for this procedure has to be marked at a flange of the – 22 s maximum for propellers with a diameter propeller shaft in the hull with "P" (purging). D ≤ 3,0 m – 30 s maximum for propellers with a diameter 2.5 The following blade positions of each blade D > 3,0 m have to be marked permanently at the hub: 4.2 The lay-out of the hydraulic system shall – maximum pitch ahead ensure that the electrically driven pumps are activated – design pitch in case that: – the mechanically driven pump fails – zero thrust position – parallel operation with the mechanically driven – maximum pitch ahead and astern pump in the lower speed range is required Chapter 2 Section 7a E Propulsors III - Part 1 Page 7a–8 GL 2012

– short adjustment times are necessary, e.g. at For nearly elliptically sections at the root area of the manoeuvring operation blade the following formula may be used instead: 2 W0,35R = 0,10 ⋅ (B ⋅ t )0,35R (9) 4.3 Each pump for the control oil has to be de- signed for a suitable angle velocity for blade adjust- 6.2 The blade retaining bolts are to be tightened ment. A guide value is 2,5° per second. This velocity in a controlled way so that the tension on the bolts is is valid for: about 60 – 70 % of their yield strength. – operation with the electrically driven pump for The shank of blade retaining bolts may be reduced to the complete speed range a minimum diameter equal to 0,9 times the root di- – operation with the mechanically driven pump at ameter of the threaded part. nominal speed of the propeller 6.3 Blade retaining bolts are to be secured against unintentional loosening. 4.4 For hydraulic pipes and pumps in the GL Rules for Ship Operation Installations and Auxiliary 7. Indicators Systems (III-1-4), Section 8 has to be applied. 7.1 Controllable pitch propeller systems are to 5. Pitch control mechanism be provided with a direct acting indicator inside the engine room showing the actual setting of the blades. For the pitch control mechanism proof is to be fur- Further blade position indicators are to be mounted nished that the individual components when sub- on the bridge and in the machinery control centre (see jected to impact loads still have a safety factor of 1,5 also GL Rules for Automation (III-1-3b), Section 4 against the yield strength of the materials used. The and Electrical Installations (III-1-3a), Section 9, B.). impact moment TM has to be calculated according to formula (6) and the resulting equivalent stresses at 7.2 Hydraulic pitch control systems are to be the different components are to be compared with provided with means to monitor the oil level. A pres- their yield strength. sure gauge for the pitch control oil pressure is to be fitted. A suitable indicator for filter clogging shall be RW⋅ p0,2 0,6R −3 provided. An oil temperature indicator is to be fitted T1,5M =⋅ 10 (6) 2 at a suitable position. ⎛⎞0,15⋅ D + 0,75 ⎜⎟ Where ships are equipped with automated machinery, ⎝⎠LM the requirements of GL Rules for Automation (III-1- 3b) are to be complied with. W0,6R can be calculated by applying the formula (7).

2 W0,6R = 0,11 B⋅ t (7) ( )0,6R E. Propeller Mounting The components have to be designed fatigue-resistant for the maximum pressure. 1. Tapered mountings for fixed propellers

6. Blade retaining bolts 1.1 Where the cone connection between the shaft and the propeller is fitted with a key, the propel- ler is to be mounted on the tapered shaft in such a 6.1 The blade retaining bolts shall be designed way that approximately 120 % of the mean torque in such a way as to safely withstand the forces in- can be transmitted from the shaft to the propeller by duced in the event of plastic deformation of the blade friction. at 0,35 R caused by a force acting on the blade at 0,9 R. At this occasion the bolt material shall have a Keyed connections are in general not to be used in safety margin of 1,5 against the yield strength. installations with a barred speed range.

The thread core diameter of the blade retaining bolts 1.2 Where the connection between propeller shall not be less than shaft cone and propeller is realised by the hydraulic oil technique without the use of a key, the necessary M ⋅α pull-up distance L on the tapered shaft is to be deter- d = 2,6 ⋅ 0,35R A (8) k mined according to formula (10). Where appropriate, dZR⋅⋅eH allowance is also to be made for surface smoothing when calculating L. . M0,35 R = W0,35R Rp0,2 LL=+mech L temp (10)

W0,35R may be calculated analogously to formula (7) where Lmech is determined according to the formulae or (9). of elasticity theory applied to shrunk joints for a III - Part 1 Section 7a E Propulsors Chapter 2 GL 2012 Page 7a–9

specific pressure p [N/mm2] at the mean taper diame- Table 7a.3 Material values ter found by applying formula (11) and for a water temperature of 35 °C . Material Modulus Poisson’s Coefficient of ratio of linear 22 2 2 2 Θ⋅TfcQT + ⋅( A ⋅ +) −Θ⋅ T elasticity thermal p = (11) E expansion Af⋅ [N/mm²] ν[-] α [1/°C] -6 T has to be introduced as positive value if the propel- Steel 205000 0,29 12,0 . 10 ler thrust increases the surface pressure at the taper. Copper based Change of direction of propeller thrust is to be ne- alloys CU1 105000 0,33 17,5 . 10-6 glected as far as absorbed power and thrust are essen- and CU2 tial less. Copper based T has to be introduced as negative value if the propel- alloys CU3 115000 0,33 17,5 . 10-6 ler thrust reduces the surface pressure at the taper, and CU4 e.g. for tractor propellers. Note 2 ⎛⎞μo 2 For austenitic stainless steel see manufacturer’s f = ⎜⎟−Θ (11a) ⎝⎠S specification

d L35t=⋅α−α⋅−m ()() (12) tempC N W 1.4 The von Mises' equivalent stress resulting from the maximum surface pressure p and the tangen- t = temperature at which the propeller is tial stress in the bore of the propeller hub shall not mounted [°C] exceed 75 % of the 0,2 % proof stress or yield Values for α and α can be taken from Table 7a.3. strength of the propeller material in the installed N W condition and 90 % during mounting and dismount- At least the temperature range between 0 °C and ing. 35 °C has to be considered.

1.3 For keyless propeller fittings without inter- 1.5 The cones of propellers which are mounted mediate sleeve, the required pull-up distance and on the propeller shaft by means of the hydraulic oil related stresses in the propeller hub and shaft can be technique should not be more than 1 : 15 and not be calculated as follows. less than 1 : 25. For keyed connections the cone shall not be steeper than 1:10. Joint stiffness factor:

d ⎡⎤11⎛⎞⎛⎞1K++22 1K 1.6 The propeller nut shall be strongly secured K =⋅m ⎢⎥ ⋅⎜⎟⎜⎟NW ++νν ⋅ − elCE⎜⎟⎜⎟22 N E W to the propeller shaft. ⎣⎦⎢⎥NW⎝⎠⎝⎠1K−−NW 1K

Values for EN, EW, νN and νW can be taken from 2. Flange connections Table 7a.3. Minimum required pull-up distance at mounting 2.1 Flanged propellers and the hubs of control- temperature 35 °C: lable pitch propellers are to be connected by means of fitted pins and retaining bolts (preferably necked Lmech = p ⋅ Kel down bolts). Minimum required pull-up distance at mounting temperature t [°C]: 2.2 The diameter of the fitted pins is to be calcu- lated by applying formula (4) given in Section 5, L = L + L mech temp D.4.3. Surface pressure at the mean taper diameter at chosen pull-up distance Lact [mm]: 2.3 The propeller retaining bolts are to be de- signed according to D.6., however the thread core pact = Lact / Kel diameter shall not be less than Related von Mises’ equivalent stresses: M ⋅ α pact 4 0,35R A σ = ⋅+3K (hub) d4,4k =⋅ V 2 N dZR⋅⋅ 1K− N eH

σV = pact (solid shaft) 2.4 The propeller retaining bolts have to be 2 σV = pact ⋅ 2 / (1 – KW ) (hollow shaft) secured against unintentional loosening. Chapter 2 Section 7a G Propulsors III - Part 1 Page 7a–10 GL 2012

F. Balancing and Testing elements from the control station to the lateral thrust unit. 1. Balancing 1.2 Documents for approval Monobloc propellers ready for mounting as well as the blades of controllable and built up fixed pitch Assembly and sectional drawings for lateral thrust propellers are required to undergo static balancing. units with an input power of 100 kW and more to- Thereby the mass difference between blades of con- gether with detail drawings of the gear mechanism trollable or built-up fixed pitch propellers has to be and propeller containing all the data necessary for not more than 1,5 %. checking are each to be submitted to GL for approval. For propellers, this only applies to an input power 2. Testing exceeding 500 kW.

2.1 Fixed pitch propellers, controllable pitch 2. Materials propellers and controllable pitch propeller systems are to be presented to GL for final inspection and Materials are subject, as appropriate, to the provi- verification of the dimensions. sions of Section 6, B. G. applies analogously to the materials and the material testing of propellers. GL reserves the right to require non-destructive tests to be conducted to detect surface cracks or casting defects. 3. Dimensioning and design In addition, controllable pitch propeller systems shall 3.1 General requirements undergo pressure, tightness and functional tests. The dimensional design of the driving mechanisms of 2.2 Casted propeller boss caps, which also serve lateral thrust units is governed by Section 5 and 6, as corrosion protection, have to be tested for tightness that of the propellers by C. at the manufacturer’s workshop. GL reserves the The pipe connections of hydraulic drive systems are right to require a tightness test of the aft propeller subject to the applicable requirements contained in boss sealing in assembled condition. Section 7b, F. 2.3 If the propeller is mounted onto the shaft by Lateral thrust units are to be capable of being oper- a hydraulic shrink fit connection, a blue print test ated independently of other connected systems. showing at least a 70 % contact area has to be dem- onstrated to the Surveyor. The blue print pattern shall Windmilling of the propeller during sea passages has not show any larger areas of contact, especially not at to be taken into account as an additional load case. the forward cone end. The proof has to be demon- Otherwise effective countermeasures have to be in- strated using the original components. troduced to avoid windmilling, e.g. a shaft brake. If alternatively a male/female calibre system is used, In the propeller area, the thruster tunnel is to be pro- between the calibres a contact area of at least 80 % of tected against damages caused by cavitation erosion the cone area has to be demonstrated and certified. by effective measures, such as stainless steel plating. After ten applications or five years the blue print For monitoring the lubricating oil level, equipment proof has to be renewed. shall be fitted to enable the oil level to be determined. 3. Quality classes of propellers For the electrical equipment of lateral thrust units, see the GL Rules for Electrical Installations (III-1-3a), 3.1 The requirements for the quality classes are Section 7, B. given in the international standards ISO 484/1 and 484/2. 3.2 Additional requirements for lateral thrust units for dynamic positioning 3.2 The quality of manufacturing and the accu- racy of the dimensions of propellers shall be adequate Bearings, sealings, lubrication, hydraulic system and to their use. all other aspects of the design are to be suitable for continuous, uninterrupted operation. Gears shall comply with the safety margins for DP as specified in Section 6, Table 6.1. The lubrication G. Lateral Thrust Units system for the gearbox shall comply with Section 6, E. 1. General For units with controllable pitch propellers, the hy- draulic system has to comply with D.7.2. The selec- 1.1 Scope tion and arrangement of filters has to ensure an unin- The requirements contained in G. apply to the lateral terrupted supply with filtered oil, also during filter thrust unit, the control station and all the transmission cleaning and exchange. III - Part 1 Section 7a H Propulsors Chapter 2 GL 2012 Page 7a–11

Where ships are equipped with automated machinery, – the size of the device with a minimum circum- the thruster unit has to comply with the requirements ferential speed of the wheel body at the nomi- for main gears and main propellers in the GL Rules nal acoustic lay-out point has to be chosen for Automation (III-1-3b). – an operation mode has to be used where the adjustment of the thrust is achieved by adjust- 4. Tests in the manufacturer's works ing the number of revolutions Section 7b, H. is applicable as appropriate. – the arrangement in the hull shall enable a dis- tance to the sonar system which is as big as For hydraulic pumps and motors with a drive power possible (stern arrangement) of 100 kW or more, the tests are to be conducted in the presence of a GL Surveyor. – for the reduction of the intake speed a low- noise gear has to be provided For lateral thrust units with an input power of less – the connection of the housing to the ship foun- than 100 kW final inspection and function tests may dation shall be established by an elastic mount- be carried out by the manufacturer, who will then ing. The foundation as part of the hull structure issue the relevant Manufacturer Inspection Certifi- shall be of appropriate stiffness cate. – the surface of the wheel body at the same level as the ship's bottom has to be coated with 5. Shipboard trials antidrumming material Testing is to be carried out during sea trials during which the operating times are to be established. 2.3 If a low magnetic signature is required, a high content of non-magnetizable materials has to be provided, for reference see the GL Rules for Special 6. Casting defects Materials for Naval Ships (II-1-6). Propellers shall be free of cracks. The correction of defects has to be executed for copper cast alloys 3. Supercavitating propellers according to the GL Rules for Materials for Propeller The blades of supercavitating propellers are to be Fabrication (II-1-5), Section 1 and for stainless steel designed to achieve a stable cavitation layer over the according to Section 2. complete blade surface at the nominal lay-out point. Lay-out and design have to observe the foreseen operation characteristics and the demanded reversing and steering ability. H. Special Forms of Propulsion Systems 4. Partially submerged propellers 1. General Partially submerged propellers are designed for an 1.1 The investigation for a propulsion system arrangement at the ship where the propeller blades most suitable for an actual naval ship should include break through the water surface. special forms of propulsion. Lay-out and arrangement Because of the high transverse forces this type of of these propulsion systems have to be coordinated propulsion is only applicable for multi-shaft propul- closely with the manufacturer of the system. sion systems. The degree of submerging has to be chosen to achieve a stable ventilation at the suction 1.2 Requirements for design and manufacturing side. have to be specified in the building specification. Concerning strength and model tests the rules for propellers have to be applied accordingly. Model 5. Water jet propulsion system tests have to be performed in order to proof the reli- ability and check special performance characteristics. 5.1 Scope These requirements apply to all devices producing a 1.3 In the following the design characteristics of thrust by jet. This includes pump jets as well as water several propulsion systems are defined. The scope jets and comparable drives. does not fulfil the demand for entirety. 5.2 Design 2. Cycloidal propellers 5.2.1 The lay-out data have to be coordinated with 2.1 Cycloidal propellers are propulsion devices the manufacturer of the water jet propulsion aggre- with blades rotating around a vertical axis and are gate. At all operating conditions no cavitation shall able to change the thrust in size and direction. occur in the pump which can lead to damage of the components. To achieve this already in the design 2.2 If low noise emission is required, the follow- phase, the manufacturer has to indicate the areas of ing principles should be observed: erosive cavitation danger. Chapter 2 Section 7a I Propulsors III - Part 1 Page 7a–12 GL 2012

5.2.2 Requirements for the manoeuvring abilities 5.6 Hydraulic system have to be specified in the building specification. 5.6.1 In case of multi-shaft propulsion each pro- 5.2.3 If it is not planned to equip all propulsion pulsion unit has to be equipped with its own, inde- units of a multi-shaft ship with manoeuvring devices, pendently working hydraulic system. it has to be ensured in the building specification that all requirements concerning rudder effect, stopping 5.6.2 Control oil pumps time, survivability and redundancy are defined and The lay-out of the control oil pumps shall follow D.4. can be met.

5.3 Arrangement

Pump shaft and entrance duct have to be arranged I. Dynamic Positioning Systems (DP Sys- parallel to the longitudinal midship plane of the ship. tems) The pump shaft shall be parallel to the waterline in the trimmed condition of the ship. The pump is to be 1. General arranged in a height that a quick start of the system is ensured for the minimum draught of the ship. 1.1 Scope The GL Rules concerning Dynamic Positioning Sys- 5.4 Construction requirements tems (I-1-15) apply to ships, which are classified by GL and are to receive the Class Notation DP 0 to DP 5.4.1 The pump has to be integrated in the hull 3 affixed to the Character of Classification. structure in a way that the maximum longitudinal and transverse forces occurring during acceleration or In the following an overview for general information crash-stop operation and during manoeuvres with the about these Rules shall be given. jet in the maximum steering position are safely with- stood. The Rules are based on the single failure concept. Detachable connections to the ship's hull shall enable 1.2 Definitions an easy installation and dismounting of the pump Control mode unit. Possible control modes of a DP control system may 5.4.2 The form of the entrance duct has to be be: coordinated with the manufacturer of the water jet – automatic mode (automatic position and head- unit. The stream towards the pump has to be continu- ing control) ous and cavitation shall be avoided in the complete inlet area. The entrance duct has to be arranged to – joystick mode (manual position control with exclude the possibility of air ingress. selectable automatic or manual heading con- trol) 5.4.3 To protect the pump from flotsam a protec- – auto track mode (considered as a variant of tion grid has to be arranged at a suitable location of automatic position control, with programmed the entrance duct. Before this grid an inspection port movement of the reference point) has to be provided. It shall be possible to open this port and have access to it at floating ship. It shall be – manual mode (individual control of pitch and possible to clean the intake protection grid by revers- speed, azimuth, start and stop of each thruster) ing the flow direction. DP-system 5.5 Manoeuvring facilities A DP system consists of components and systems acting together to achieve sufficiently reliable posi- 5.5.1 Steering nozzle tion keeping capability. The adjusting angle of the steering nozzle shall reach The complete installation comprises the sub-systems: 30° to each side. If no time for adjusting is defined in – power system the building specification a value less than 8 s has to – thruster system and be assumed for the complete range of 60°. – control system 5.5.2 Thrust reversing device The requirements of the DP system configuration for If no time for adjusting is defined in the building the different Class Notations are shown in Table 7a.4. specification a value of not more than 10 s has to be Position keeping assumed for the adjusting from "full ahead" to "full astern". The neutral position of the thrust reversing Maintaining a desired position and heading or follow- system (zero thrust position) has to be marked at the ing a predefined track within the critical excursions control device. or otherwise the specified excursions as specified in III - Part 1 Section 7a I Propulsors Chapter 2 GL 2012 Page 7a–13

the DP operation manual of the DP system and under dancy requirements according to Table 7a.4 are to be the defined environmental conditions. fulfilled. Single failure 2.2.3 For Class Notation DP 2, a loss of position The single failure concept assumes that only one may not occur in the event of a single fault in any (single) failure is the initiating event for an undesired active component or system. Static components will occurrence. The simultaneous occurrence of inde- not be considered to fail where adequate protection pendent failures is not considered. However, common from damage is demonstrated and reliability is mode failures are to be examined. deemed acceptable by GL. WCF – Worst Case Failure 2.2.4 For Class Notation DP 3, a loss of position The identified single failure mode in the DP system may not occur in the event of a single fault in any resulting in maximum effect on DP capability as active or static component or system. determined through FMEA study. This applies also for the total failure of one compart- This worst case failure may be used in a consequence ment due to fire or flooding. analysis. 2.2.5 For Class Notations DP 2 and DP 3, a single 1.3 Documents for approval inadvertent action shall be considered as a single fault, if such an action is reasonably probable. 1.3.1 The documents and drawings specified be- low are to be submitted for approval electronically 2.2.6 If the DP control system is tested with a via GLOBE 1 (see A.2.) or in paper form in triplicate, special “hardware-in-the-loop” test (during FAT and maintenance manuals in a single set: on board) a respective entry in the Technical File of – general description of the system the Class Certificate is possible. – test programs for factory acceptance test and DP control trial 2.2.7 DP systems which exceed the requirements for Class Notation DP 2 or DP 3 (e.g. separate fuel, – documentation for control, safety and alarm cooling water system for each diesel engine) a re- systems including test program spective entry in the Technical File of the Class Cer- – thruster documentation tificate is possible. – electric power system documentation 3. Functional requirements 1.3.1 Failure Mode and Effect Analysis (FMEA) 3.1 Ships with Class Notation DP 0 are able to A failure mode and effect analysis (FMEA) concern- keep their position at least in automatic mode. ing availability of the DP system after a single failure shall be provided for Class Notation DP 2 and DP 3. 3.2 Ships with Class Notation DP 1 are able to keep their position at least in automatic mode and 2. Requirements for Class Notations joystick mode.

2.1 Reliability 3.3 Ships with Class Notation DP 2 fulfil the The necessary reliability is determined by the conse- requirements of DP 1 and are able to keep their posi- quence of a loss of position keeping capability. The tion after a single failure in an active component. larger the consequence, the more reliable the DP system shall be. 3.4 Ships with class notation DP 3 fulfil the Consequently the requirements have been grouped requirements of DP 2 and are able to keep their posi- into five Class Notations. For each Class Notation the tion after a single failure in an active or static compo- associated single failure criteria shall be defined. nent. This applies also for the total loss of the equip- ment in one compartment due to fire or flooding. The Class Notation of the ship required for a particu- lar operation is based on a risk analysis of the conse- 3.5 In order to meet the single failure criteria quence of a loss of position. redundancy of components will normally be neces- sary as follows: 2.2 Class Notations − For class notation DP 2, redundancy of all 2.2.1 For Class Notation DP 0, loss of position active components. may occur in the event of a single fault. − For class notation DP 3, redundancy of all 2.2.2 For Class Notation DP 1, a loss of position active and static components and physical sepa- may occur in the event of a single fault. The redun- ration of DP relevant systems. Chapter 2 Section 7a J Propulsors III - Part 1 Page 7a–14 GL 2012

4. Tests 5. Full information The full and binding requirements concerning dy- 4.1 Factory acceptance test (FAT) namic positioning are defined in the GL Rules for Dynamic Positioning Systems (I-1-15). Before a new installation is surveyed and tested fac- tory acceptance tests shall be carried out at the manu- facturer’s work. These tests are to be based on an J. Cavitation Noise of Propellers approved program and shall demonstrate full compli- Fig. 7a.2 shows the probable and unprobable ranges ance with the redundancy concept, if applicable. for cavitation depending on the thrust load coeffi- cient. 4.2 Newbuilding survey Cavitation inception number: pp− SIGMA = SV 4.2.1 Newbuilding survey, which shall include a n 2 complete survey of the DP system to ensure full com- 0,5⋅ρ ( π⋅ D ⋅ n2 / 60) pliance with the rules. D has to be inserted in metres Thrust load coefficient: 4.2.2 This survey includes a complete test of all T C = DP relevant systems and components (DP control Th 2 trial). For details see GL Rules according to 5. 0,5⋅ρ⋅ vAD ⋅ A

Table 7a.4 Minimum requirements for DP systems Minimum requirements for Class Notation Subsystem or component DP 0 DP 1 DP 2 DP 3 redundant, separate Generators and prime mover -- redundant compartments 2 Main switchboard 1 2 in separate compartments Power Bus-tie breaker -- 2 NO 1 2 NO system redundant, through Distribution system -- redundant separate compartments redundant, separate Power management -- redundant compartments UPS for DP control system -- 1 2 2 + 1 in separate compartments redundant, separate Thruster Arrangement of thrusters -- redundant compartments, provided WFC system is not exceeded redundant, separate DP relevant auxiliary systems -- redundant 2 compartments 2 + 1 no. of computer systems 1 2 DP- in separate compartments Control independent joystick with auto system -- 1 1 1 heading 3 Position reference systems 1 2 3 whereof 1 connected to back- up control system Sensors Wind 1 2 2 one of each Ship's VRS 1 2 2 connected to sensors back-up control Gyro 1 3 3 system redundant, Essential non-DP systems -- redundant separate compartments Printer Yes yes yes

1 NC bus-tie breakers may be accepted depending on the findings of the FMEA and additional testing (NO = nominally open, NC = nominally closed) 2 when active components are used 3 see GL Rules for Dynamic Positioning Systems (I-1-15), Section 2, B.6. for essential non-DP systems

III - Part 1 Section 7a J Propulsors Chapter 2 GL 2012 Page 7a–15

1,0

0,7 cavitation unprobable

0,5 n

0,4

0,3

cavitation probable 0,2 Cavitation inception number SIGMA Cavitation inception number SIGMA

0,1 0,1 0,2 0,3 0,5 1,0 2,0 Thrust load coefficient C Th

Fig. 7a.2 SIGMAn - CTh - diagram for cavitation noise of propellers

III - Part 1 Section 7b A Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–1

Section 7b

Azimuthing Propulsors

A. General 2. Documents for approval

2.1 General 1. Scope Design drawings of azimuth propulsors in main pro- 1.1 Types of propulsors pulsion systems are to be submitted to GL for ap- proval. The drawings are required to contain all the Azimuthing propulsors cover all steerable devices details necessary to carry out an examination in accor- with geared torque transmission (rudder propeller) and dance with the following requirements. To facilitate a main propulsion motor in an underwater gondola smooth and efficient approval process they should be (podded drives). Fixed podded drives (booster) have submitted electronically via GLOBE 1. In specific to comply with this Section as far as applicable. cases and following prior agreement with GL they can also be submitted in paper form in triplicate. The requirements of this Section are valid for azi- muthing devices as main propulsion systems. The Project specific documents shall always clearly de- ship's manoeuvring station and all transmission ele- scribe the design which is to be realised (no descrip- ments from the manoeuvring station to the azimuthing tion of possible serial variations and possibilities). propulsor are specified in the GL Rules for Electrical Drawings shall contain necessary dimensions and Installations (III-1-3a), Section 13. material specification / mechanical properties. A general brief functional description including defi- They have to be complied with, as far as they are nition of load cases as a basis for strength calculation applicable for the respective individual design. for the individual components, limitations and capa- bilities of the azimuthing propulsor should demon- 1.2 Operating conditions strate the adequate design to the specified special requirements of the respective ship application. A faultless continuous operation under the specified ambient and operational conditions is required. Com- The following drawings and documents are to be ponents which can not easily be changed without dry- submitted for approval: docking the ship and without going out of service or having enough redundancies have to be designed for a 2.2 Overall system life- and/or service time cycle of 5 respectively 6 years – arrangement drawing of the complete azi- minimum. If this period cannot be guaranteed, GL has muthing propulsor and definition of forces act- to be informed about the respective faultless continu- ing on the hull ous service time already at the time of class applica- tion. – sectional drawing of the entire azimuthing pro- pulsor Azimuthing propulsors serve as driving and steering – protection concept including list of sensors and device. As long as they are used for steering, a certain their initial limits (document) fraction of the thrust is not available for driving in forward direction. The concept of the ship, created by – complete list of measuring points, type of sensor the Naval Administration and shipyard, has to take safety and alarm system, incl. detailed descrip- into account, that even under severe weather condi- tion (drawing and document) tions while keeping the course, the remaining thrust – fire protection (document) podded drives only fraction for driving the ship forward is sufficient. This has to be fulfilled for all loading conditions. GL re- – ventilation system (drawing) podded drives only serves the right to request for an appropriate demon- stration. – heat balance and cooling system (document and drawing) podded drives only The spaces, where the azimuthing propulsors are – description of test procedures at different as- mounted, are regarded as steering gear room. The sembly stages, quay and sea trial (document) respective environmental conditions apply.

For the design of podded drives, it has to be taken into –––––––––––––– account that most of the components are not accessi- 1 Detailed information about GLOBE submission can be found ble. on GL’s website www.gl-group.com/globe. Chapter 2 Section 7b B Azimuthing Propulsors III - Part 1 Page 7b–2 GL 2012

– quality assurance and inspection plan (docu- – functional description for podded drives ment) podded drives only only and other new designs

– definition of overall control system 2.5 Electrical components – Failure Mode and Effects Analysis podded The documentation of electrical components is speci- drives only (where required) fied in the GL Rules for Electrical Installations (III-1- 3a), Section 13. 2.3 Structural components – scantling of structural parts of the housing, 2.6 Maintenance steering pipe/strut and well (drawings) (podded drives only and propulsors above 2500 kW) – loading cases to represent highest loads in nor- mal sailing, manoeuvring and emergency condi- – maintenance plan (expected life time) tions (document) – inspection arrangement (underwater, inside pod) – stress calculation esp. ratio calculated/permiss- – clearance of slewing bearing, normal and critical ible (document) – condition monitoring arrangement, upper and – fatigue analyses, as far as requested (calcula- lower bounds tion) – foundation and connection with ship structure 3. Reference to further Rules (drawing ) 3.1 GL Rules 2.4 Mechanical components – Ship Operation Installations and Auxiliary Sys- – propeller (drawings) tems (III-1-4) – shafting (drawings) – Electrical Installations (III-1-3a) – shaft roller bearings (life time calculation) – Automation (III-1-3b) – connecting elements as bolts, couplings, – Guidelines for the Seating of Propulsion Plants clutches, etc. (drawings and calculation) and Auxiliary Machinery (VI-4-3) – slewing and slip ring bearings – Propulsors (III-1-2), Section 7a – lubrication and hydraulic systems (diagram) 3.2 Other Rules and regulations – seals, sealing systems including emergency seal system (if applicable) (drawings and functional – IEC 60092: Electrical Installations in Ships, Part description) 501: Special features – Electric propulsion plant, Podded Drives – torsional vibration calculations as required (see Section 8), additionally for the load case: – blade loss case B. Materials – shaft locking device (drawing and calculation): – calculation of brake moment, description of 1. Approved materials locking procedure The selection of materials is subject, as and where – bilge system for drainage, podded drives only applicable, to the provisions for approved materials (diagram) defined in the GL Rules for Ship Operation Installa- tions and Auxiliary Systems (III-1-4), Section 2, B.2.1 – steering gear: and to those of Sections 5, 6 and 7a. – assembly and detailed drawings of all im- portant load and torque transmitting single Materials have to comply with the GL of Rules Mate- components rials and Welding (II). Special requirements are con- tained in the respective Chapter. – gear calculation – hydraulic diagram for steering 2. Testing of materials – hydraulic power pack (or equivalent for All important components of the azimuthing propulsor azimuth rotation) involved in the transmission of torque, thrust, bending moment or hydraulic pressure are to be tested under – mechanical key on slewing bearing, lock- the supervision of GL in accordance with the GL ing device (drawing) Rules of Metallic Materials (II-1). III - Part 1 Section 7b C Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–3

C. Design of Azimuthing Propulsors 5. Gears and couplings

1. Number of azimuthing propulsors 5.1 Gear design Each ship shall be equipped with at least two azi- 5.1.1 Gears or toothed connections have to comply muthing propulsors. Both units are to be capable of with the requirements defined in Section 6. being operated independently of the other. The failure of one azimuthing propulsor or its control system, In case of electrically driven azimuthing propulsors, a converter or motor shall not cause the failure of other safety of SF = 1,35 and SH = 1,15 respectively against devices (see IEC standard 60092-501, 4.1.4). This has static load (less than 1000 load cycles) of 1,6 M nomi- to be demonstrated by a FMEA. nal has to be demonstrated for the tooth root and flank.

2. Load cases for scantling 5.1.2 Curved tooth couplings have to be dimen- For scantling of components the respective worst case sioned according to the Rules of Section 6, G.3. for has to be considered, except for life time calculations. tooth couplings. The maximum attainable torque at respective rpm has to be considered. The following load cases should be 5.2 Lubrication taken into account at minimum: The lubricating and/or cooling oil supply is to be en- – full ahead (maximum torque including possible sured by a main pump and an independent standby overload of an electric motor) pump. – bollard ahead and astern, if applicable In the case of separate lubricating systems in which the main lubricating oil pumps can be replaced by – loss-off one propeller blade at 0,35 radius (un- means available on board, the standby pump may be balance at full rpm; bending moment replaced by a complete spare pump. This spare pump – maximum steering at full speed (sailing into is to be carried on board and is to be ready for mount- turning circle) ing. – maximum steering at maximum manoeuvring Oil level indicators and filters are subject to the provi- speed sions of F.4. and F.5. wherever relevant. – crash stop The oil temperature has to be measured. A heat ex- Additionally for electric main propulsion motor (IEC changer has to be provided, if higher than allowable 60092-501, 4.3): temperatures can be expected under unfavourable environmental conditions. – highest steady state torque in three phase short- circuit of the motor, if exceeding crash stop val- 6. Shafting ues – highest oscillating torque during two phase 6.1 Shaft short-circuit of the motor, if exceeding crash stop values 6.1.1 For the dimensioning of the propeller shaft between propeller and gear wheel, see Section 5. For If the naval ship is assigned an ice class, additional the dimensioning of the remaining part of this shaft requirements are defined in Section 9. and all other gear shafts see Section 6.

3. Screw propeller 6.1.2 In case that the propeller shaft coincides with Screw propellers have to comply with the require- the electric motor shaft, it has to be ensured that in hot ments defined in Section 7a. and cold condition and while acting all reasonable forces, the shaft is stiff enough to guarantee an appro- For propeller shrink fit calculation the thrust has to be priate gap between rotor and stator of the motor. taken into account with a negative sign in case of pulling propellers. 6.2 Shaft bearings

4. Electric propulsion motor 6.2.1 Shaft bearings are normally of roller type. They have to be so arranged that a sufficient load in The requirements of the electric propulsion motor are all operational conditions is applied. The oil tempera- specified in the GL Rules for Electrical Installations ture has to be measured. (III-1-3a), Section 13. The required supervision of construction has to be extended to the respective power supply systems. 6.2.2 The expected lifetime has to be given and proven by a lifetime calculation. Instructions for main- The air humidity of electric motors, operating in a tenance have to be provided. An inspection of the closed ventilation loop, has to be monitored. bearings, e.g. by endoscope has to be enabled. Chapter 2 Section 7b C Azimuthing Propulsors III - Part 1 Page 7b–4 GL 2012

6.2.3 For podded drives the wear of bearings has to 6.4 Locking device be monitored, if they are not accessible. It shall be possible to take an oil sample. 6.4.1 Each azimuthing propulsor is to be provided with locking devices to prevent the unintentional rota- 6.2.4 For podded drives the thermal expansion of tion of the propeller shaft in case of a failure (see also the shaft and housing has to be taken into account. IEC 60092-501, 13.2.3). The locking device of the The temperature of the bearing has to be monitored propeller shaft is to be designed to securely lock the redundantly and independent from the alarm system non-operated propeller while operating the ship with and a two stage alarm has to be delivered. In excep- the maximum power of the remaining propulsors, tional cases where a sufficiently forced lubricating oil however at a ship speed of at least 8 kn. flow is applied, the oil temperature can be measured instead of. Sufficient redundancy of forced lubrication 6.4.2 Clutch / Brake has to be ensured, e.g. by a second pump (see also IEC Where a clutch /brake is introduced to serve as a lock- 60092-501, 12.2.1) and the flow has to be monitored. ing device, an unintentional operation has to be Switching over to the redundant system shall be per- avoided. In case the clutch / brake is not dimensioned formed automatically and shall be alarmed. according to the maximum motor torque, a preventive measure has to be introduced to avoid an overloading 6.2.5 For podded drives, a continuous control of of the device. An engaged clutch / brake has to be the lubrication has to be provided redundantly and indicated at the control station. independent from the alarm system (see IEC 60092- 501, 13.2,2). A two stage alarm has to be delivered. 7. Bilge system (for podded drives only) In case of oil lubricated bearings, the maximum and minimum level has to be monitored. The monitoring 7.1 The gondola and other separately closed of the minimum level shall be operable under all nor- rooms, e.g. for the electric propulsion motor, of the mal operational conditions. podded drive have to be equipped with an effective bilge system in order to prevent liquid ingress into the 6.2.6 For podded drives, measures should be taken motor or other functionally essential components. The to prevent the circulation of electrical current between gondola bilge has to be large enough in order to col- the shaft and the bearings. lect the liquid safely if a seal element fails and has to ensure that the pipe(s) gets the liquid reliably out of 6.3 Shaft sealing the gondola. The system has to be dimensioned so that a sufficient suction capacity of at minimum 5 6.3.1 For podded drives, the shaft seal has to pro- times the maximum allowable leakage rate of all seals tect the motor and other functionally essential compo- feeding the bilge system is continuously guaranteed. nents against a liquid ingress with a sufficient safety and redundancy. In case of malfunction of one of the The suction pipe is to be positioned in such a way that tightening parts of the seal, measures have to be taken due to a failure at the highest level the flushing of the to get the leakage information as an alarm into the fluid inside the pipe does not cause any harm for the ships information system. The seal has still to protect motor or other equipment. the functionally essential components safely. A main and auxiliary bilge system has to be provided 6.3.2 The shaft seal has to cope with the axial ex- for the bilges protecting the propulsion motor. pansion and movements of the shaft. 7.2 The bilge level shall be monitored by at 6.3.3 The header tank has to be equipped with a minimum two independent sensors. Any abnormal minimum level sensor. A maximum level sensor is leakage has to be indicated with an alarm. A two stage highly recommended. The piping system with header alarm level is required, indicating “high” and “high tank, position and kind of level sensors has to be sub- high” level. mitted for approval. If the seal is type approved a schematic sketch with piping is sufficient, otherwise The bilge in the gondola has to be equipped with an full drawings have to be submitted. analogous sensor, monitoring the bilge level and its change. If the pipe(s) cannot empty the bilge, the high 6.3.4 The seal has to protect the sea water against high level alarm has to indicate the possible flooding pollution if there is an oil leakage. The oil leakage has of the gondola and a shut-down of the motor should be also to be indicated as soon as a specified maximum requested. An automatic shut-down is allowed. permissible leakage is exceeded. 8. Ship foundation, support pipe and gondola 6.3.5 For podded drives, an emergency sealing device, suitable to seal the propeller shaft while the 8.1 The design of the support pipe and gondola shaft locking device is active, has to be provided (see and their attachment to each other and the ship's hull IEC 60092-501, 13.2.3). The operability of the system has to take account of the loads due to the propeller shall be indicated and shall be checked on a regular and nozzle thrust including the dynamic components basis. Any failure of the system has to be alarmed. and due to steering. For load case scenarios see 2. III - Part 1 Section 7b D Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–5

8.2 Additionally the ships foundation and propul- vices. No single fault and ship speed and steering sor casing has to be stiff enough to limit the deflec- position should prevent the remaining steering devices tions at the connecting points to rotating mechanical from fulfilling the SOLAS requirements (see 3. and parts in order to enable a reliable operation under 4.) relevant thermal and mechanical load conditions. 2. Overload protection and steering angle limitation 2.1 Power-operated steering device systems are D. Design of Steering Device to be fitted with overload protection (slip coupling, The following paragraphs are applicable, so far no relief valve or comparable) to ensure that the steering other means are installed to enable the ship's steering device is not harmed by e.g. accidental thruster azi- capabilities, as required by SOLAS Chapter II-1, 29. muthing. The overload protection device is to be se- cured to prevent later adjustment by unauthorized For podded drives see also IEC 60092-501, 13.7. persons. Means shall be provided for checking the Azimuthing propulsors absorbing 2500 kW or more setting while the ship is in service. installed on one ship are regarded as steering devices 2.2 The steering angle in normal operation (sea having a rudder stock diameter in excess of 250 mm in mode) has to be limited to the declared steering angle, order to comply with SOLAS Reg. 29. e.g. by limit switches. Since azimuthing propulsors are In case of a sudden inoperability of all steering de- intended to turn 360°, any mechanical stoppers, re- vices (e.g. black out) the steering angle has to be kept quired for normal rudders, have to be replaced by under all weather and sea conditions until an emer- adequate alternative means. Those alternative means gency steering is possible. have to be independent from the declared steering angle limit switches. 1. Number of steering devices This limitation can be switched off (harbour mode), as Each azimuthing propulsor has to be equipped with at soon as means are active (e.g. speed, power limitation) least one main and one auxiliary steering device. Both to avoid manoeuvring which endangers the ships steering devices are to be independent of each other safety. and, wherever possible, act separately upon the pro- If any unintentional use of the steering device at the pulsor (slewing bearing). A fault in one steering de- most unfavourable ships condition (e.g. maximum vice shall not influence the remaining one(s). GL may speed) does not endanger the ship (which has to be agree to components being used jointly by the main demonstrated at the sea trial), a limitation of the steer- and auxiliary steering device. A comparison of con- ing angle may be dispensed from. ventional rudder components and the respective parts of an azimuthing propulsor is given in the Table 7b.1. How to operate the steering module, the range of op- eration and all related constraints, e.g. power reduc- For podded propulsors it has to be demonstrated by a tion if steering angle exceeds the declared steering comprehensive FMEA that no single fault in one angle, as well as the crash stop procedure have to be steering device leads to an inoperability of both de- described and submitted.

Table 7b.1 Comparison between conventional steering gear and azimuthing propulsor

Required redundancy Conventional steering gear Azimuthing propulsor No Rudder stock Slewing ring, housing (support cone) Contact area of gear connection No Hub of tiller (teeth/teeth) 1 Pinion wheels and shafts (and Yes Tiller arms, chamber walls (wings) reduction gears, if present) Hydraulic cylinders; chambers of Yes Hydraulic / electric motors rotary gear Hydraulic piping / electric power Yes Hydraulic piping supply Yes Hydraulic power unit Hydraulic power unit / converters

1 With respect of redundancy as recommended by SOLAS, main and auxiliary steering system should act autonomously on the rudder stock. This is guaranteed if there are more than one actuating hydraulic / electric motor without inline hydraulic / electric power supply / electric motor, they can be separated and disengaged (prevention of blocking).

Chapter 2 Section 7b D Azimuthing Propulsors III - Part 1 Page 7b–6 GL 2012

2.3 If SOLAS shall be applied in the sense of The requirements of electrically driven auxiliary required manoeuvrability for a ship a "declared steer- steering devices have to be realised accordingly. ing angle" 2 is introduced. The maximum angle at which the azimuth propulsor can be oriented on each 5. Locking mechanism side when the ship navigates at its maximum speed (sea mode) is to be specified by the Naval Admini- A locking mechanism has to be provided in order to stration. Such maximum angle is generally to be less fix the azimuthing propulsor in a desired position. than 35° on each side. The mechanism has to withstand all the loads which may occur during operating the unit with the maxi- 2.4 Helm angle in excess of the declared steer- mum power. It has to be shown that the application of ing angle may be used below a certain ship speed the locking device can be done within a reasonable (manoeuvring mode) as soon as the ships safety is not time, independent from weather and sea condition. endangered, while the steering device is unintention- ally used. A power limitation may be required so that 6. Power unit the safety of the ship is not endangered. 6.1 Hydraulic device 2.5 Manoeuvres possibly conflicting with design features of the azimuthing propulsor or the ship have 6.1.1 Where power operated hydraulic main steer- to be blocked by automatic control. ing gears are equipped with two or more identical power units, no auxiliary steering gear needs to be 3. Main steering device installed provided that the following conditions are fulfilled:. The main steering device has to be capable to turn the azimuthing propulsor from one side at the declared – two independent and separate power actuating steering angle to the opposite side at the declared systems (power unit(s), hydraulic pipes, power steering angle with a speed of 2,5 s/° at maximum actuator), each capable of meeting the require- ship service speed. ments as set out in 3. and 4. or For electric propulsion motors, the main steering – at least two identical power actuating systems device should be fed from the same switchboard part which, acting simultaneously in normal opera- as the motor. tion, are to be capable of meeting the require- ments as set out in 3. and 4. 4. Auxiliary steering device (podded drives only) 6.1.2 In the event of failure of a single component Auxiliary steering devices shall, with the azimuthing of the main steering gear including the piping, ex- propulsor fully immersed in calm water, be capable cluding the slewing bearing means are to be provided of putting the propulsor from 15° port to 15° star- for quickly regaining control of one steering system board or vice versa within 60 seconds at 50 % of the (podded drives only). ship's maximum speed, subject to a minimum of eight knots. Hydraulically operated auxiliary steering de- 6.1.3 In the event of a loss of hydraulic oil, it has vices shall be fitted with their own piping system to be possible to isolate the damaged system in such a independent of that of the main steering device. The way that the second steering system remains fully pipe or hose connections of steering devices shall be operable. capable of being shut-off directly at the pressurized 6.1.4 At least one electrically driven hydraulic casings. pump has to be fed from an other switchboard. In case of a failure of the main steering system the auxiliary steering device is at least to be capable of 6.2 Electric device moving the azimuthing propulsor to midship position, where the unit can be locked. Manual operation is The requirements of the GL Rules for Electrical In- acceptable as an emergency solution, if the auxiliary stallations (III-1-3a), Section 7, A. have to be ful- steering device is out of operation. filled. The auxiliary steering device has to be capable to The electrical main steering device has to be fed from keep the propulsor at the current position, if the main the switchboard of an electrical power generating steering device fails, even the ship is sailing at full plant. At least one (auxiliary) steering device has to speed. be fed from an other switchboard. The electric device has to be protected against over- current and short-circuit. –––––––––––––– 7. Control and monitoring 2 Declared steering angle is at minimum the helm angle at which the vessel shows a comparable manoeuvring behaviour as it would show, when equipped with a conventional rudder 7.1 Both the propeller drive and the steering at 35° helm angle with maximum steering force. device of each azimuthing propulsor are to be con- III - Part 1 Section 7b D Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–7

trolled from a manoeuvring station on the navigating cally or hydraulically, the steering angle is to be bridge. indicated by a device (local steering device position indicator) which is mechanically actuated either by The controls of each individual azimuthing propulsor the steering device itself or by parts which are rigidly are to be mutually independent and so designed that connected to it. In case of time-dependent control of the azimuthing propulsor cannot be turned uninten- the main and auxiliary steering device, the midship tionally. position of the steering device is to be indicated on An additional combined control for all azimuthing the bridge by some additional means (signal lamp or propulsors is permitted. similar). In general, this indicator is still to be fitted even if the second control system is a manually oper- 7.2 Failures of single control components (e.g. ated hydraulic system. See also the GL Rules for control system for variable displacement pump or Electrical Installations (III-1-3a), Section 9, C. flow control valve) which may lead to loss of steering The steering position of the azimuthing propulsor at shall be monitored by an audible and visible alarm on any moment is also to be indicated at the steering the navigating bridge, if loss of steering cannot be device itself. prevented by other measures. It is recommended that an additional steering angle 7.3 Means have to be provided, fulfilling the indicator has to be fitted at the machinery control same purpose as the steering angle limitation to the centre. declared steering angle on both sides in normal ser- vice (sea mode). Those means shall limit the steering 8. Dimensioning of components angle effectively and may trigger a power reduction of the propulsion motor. These may be dispensed 8.1 Scantling of steering torque transmitting with by GL in cases where no danger for the ship is components caused by unintentional slewing of the azimuthing propulsors at full power and ship speed to any angle. The most severe loads on the components of the A safety system has to be realised according to the steering device determined from the load cases de- GL Rules for Electrical Installations (III-1-3a), Sec- fined in C.2. are not to exceed the yield point of the tion 9, C. for cases, where the steering angle limita- materials used. Additionally a torque of 2,5 times the tion fails. The failure of the steering angle limitation maximum operational torque (corresponds to the has to be alarmed. rudder stock yielding torque) has to be used for scant- ling with a safety factor of 1,3 against yield strength. It shall be possible in the sea mode that the limita- The design of parts of the steering device with over- tions can be overruled by an emergency crash stop load protection is to be based on the loads corre- manoeuvre. sponding to the response threshold of the overload protection with a safety factor of 1,3. 7.4 The failure of a single element within the control and hydraulic / electrical azimuthing system It is assumed that the most severe loads occur sel- of one unit shall not lead to a failure of another unit. dom. If they occur more frequently, their influence on the fatigue has to be taken into account. 7.5 Where the hydraulic / electric systems of more than one azimuthing propulsors are combined, 8.2 Slewing Bearing it is to be possible in case of a loss of hydraulic oil or electrical fault to isolate the damaged system in such 8.2.1 A lifetime calculation and a calculation of a way that the other control system(s) remain fully the safety factor for static load have to be provided. operational. The lifetime calculation should show a sufficient dimensioning to obtain a lifetime period of 40000 h. 7.6 Local control A safety factor of 1,8 at minimum has to be obtained from static load calculation. Means are also to be provided for exercising control from the propulsor machinery compartment. The 8.2.2 At least one inspection opening has to be transmission system is to be independent of that serv- provided in order to inspect the tooth contact pattern ing the main control station. Requirements for the and lubrication situation. local control station are defined in the GL Rules for Electrical Installations (III-1-3a), Section 13, H. 8.2.3 Seals have to be provided to protect the It shall be possible to move the azimuthing propulsor slewing bearing from sea water ingress and from any into a favourable position and to start the main pro- oil / grease leakage. If the sealing is grease lubri- pulsion motor again, e.g. after a black out. cated, a sufficient space has to be provided to ac- commodate the old grease of one docking period. 7.7 Steering angle indication 8.3 Slewing gear The position of the azimuthing propulsor is to be clearly indicated at the bridge and at all steering sta- The slewing gears are in general to be designed as tions. Where the steering device is operated electri- cylindrical, bevel or worm gears, applying a steering Chapter 2 Section 7b E Azimuthing Propulsors III - Part 1 Page 7b–8 GL 2012

moment until safety valve or overload protection The calculation of necessary diameter for mounting device operates. the propeller blades see Section 7a, D.6., for the hub and flange couplings see Section 7a, E.2. For all other 8.3.1 Scantling screws, except foundations, a safety factor of 1,5 against yielding has to be demonstrated for the most The scantlings of slewing gears have to follow the severe load case. For the dimensions of foundation calculation procedure as described in Section. 6. bolts see the GL Guidelines for the Seating of Pro- pulsion Plants and Auxiliary Machinery (VI-4-3). The application factor KA has to be calculated for the submitted load spectrum according to ISO 6336, Part Washers are normally not permitted. 6. Screws have to be secured against unintentional loos- The manufacturer has to submit the maximum torque ening. at which either the safety valves open or the safety The material requirements for screws have to be clutch is disengaged. fulfilled, see the GL Rules for Steel and Iron Materi- als (II-1-2), Section 6, C. Depending on the application a respective load spec- trum has to be submitted and its suitability to be 1.3 Fitted bolts and shear pins demonstrated. A three step load spectrum has to be used for scantling and its suitability to be demon- Wherever torque or shear forces have to be transmit- strated. ted safely by bolt/pin connections, fitted bolts/pins should be applied. A torque/shear transmission by For the resulting equivalent load a safety of SF = 1,8 friction created by screws of the same connection, and SH = 1,3 has to be demonstrated for unlimited may be taken into consideration at the discretion of load cycles. GL. Dimensions of fitted bolts/pins can be calculated for connections of propeller blade according to Sec- In case of a worm gear the minimum life cycle is not tion 7a, D.6., for hub and flange couplings according to be less than one class period with a minimum wear to Section 7a, E.2. Fitted bolts/pins can be replaced safety SW = 1,3. The lubrication of the worm has to by stoppers in suitable applications, as e.g. for ma- be performed by an individual separate circulation. chinery foundations, see the GL Guidelines for the Seating of Propulsion Plants and Auxiliary Machin- 8.3.2 Operation ery (VI-4-3), Section 1, B. For all other fitted bolts/pins a safety factor of 1,5 against yielding ap- A sufficient lubrication has to be ensured and a pos- plying the most severe load has to be demonstrated. sibility to check lubrication at reasonable time inter- vals has to be realised. Fitted bolts have to be secured against unintentional loosening. An opening for a visual tooth inspection has to be The material requirements for forgings have to be provided (inspection cover). fulfilled, see the GL Rules for Steel and Iron Materi- als (II-1-2), Section 3, D.

2. Fitting systems E. Auxiliary Equipment 2.1 Shrink fit 1. Bolts and screws A shrink fit calculation has to be submitted for all shrunk joints for torque transmission, for fluid-tight 1.1 General connections or for the safety relevant or functionally essential components. A contact area of more than GL may dispense from the submission of detailed 70% with equally distributed contact has to be en- drawings as defined in A.2.4 in case of using stan- sured. dardised screws. GL may also dispense from delivery of a 3.2 material certificate, if the screw size is below The safety factor against slippage has to be chosen M 39 and is manufactured in a well supervised mass according to the respective application, using the production. following minimum guide values: – propellers: 2,8 1.2 Screws – couplings between propeller and gear box: 2,5 Where necessary, a sufficient lengthening of the – within gear box: 3,0 screw by applying a torque, which usually generates – between gear box and motor: 3,0 a stress of up to 90 % of yield point, has to be dem- onstrated by calculation for essential connections, The safety factor against yielding has to be chosen transmitting propulsion torque, thrust and bending according to the respective component (due to ge- moments. The female thread strength has also to be ometry and production process), using the following considered. minimum guide values: III - Part 1 Section 7b F Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–9

– propeller 1,33 for service (75 % At points where they are exposed to danger, copper of yield strength) pipes for control lines are to be provided with protec- tive shielding and are to be safeguarded against hard- 1,11 for mounting and ening due to vibration by the use of suitable fasten- dismantling (90 % of yield ings. strength) 1.3 GL reserves the right to permit short hoses – coupling 1,25 for service (80 % or metallic compensators (flexible pipes) instead of of yield strength) pipes in case of connections to moving parts or com- 1,05 for mounting and parable situations. dismantling (95 % of yield strength) 1.4 Connections to other hydraulic systems are not permitted. 2.2 Keyed shaft connections 2. Dimensioning Requirements as set out in Section 7a for propulsors and Section 5 for main shafting have to be applied. For the design and dimensions of pipes, valves, fit- tings, etc., see the GL Rules for Ship Operation In- 3. Cooling systems stallations and Auxiliary Systems (III-1-4), Section 8 and for pressure vessels Section 16.

3.1 The cooling system of the motor or oil has to For the determination of the maximum allowable be dimensioned according to the most critical condi- working pressure the frictional losses in the steering tions: gear including piping are to be considered. The relief valves are to be set at this pressure value. – full power

– highest ambient temperatures 3. Application for steering device

– lowest possible ship speed 3.1 If hydraulic power is used for the steering gear of the azimuthing propulsor it shall not be in 3.2 In general the most difficult situation can be direct connection with other hydraulic systems. described by maximum water and air temperature (see Section 1, D.) and the propulsor running at maxi- 3.2 The pipes of hydraulic steering devices are mum shaft speed. to be made of seamless or longitudinally welded steel tubes. The use of cold-drawn, unannealed tubes is not 3.3 If the cooling system does not allow to de- permitted. liver the maximum power under the described condi- tions, the maximum attainable power has to be con- 3.3 The pipes of hydraulic steering devices are sidered to fulfil A.1.2. The above described situation to be installed in a way ensuring maximum protection has to be reflected in the heat balance, which has to while remaining readily accessible. be submitted for approval on request of GL.

For the cooling system of podded drive motors see 4. Filters also IEC 60092-501, 7.3 and 12.3. Filters for cleaning the operating fluid are to be lo- cated in the piping system. It shall be possible to change oil cleaning filters without interruption of oil supply. F. Hydraulic Systems 5. Tanks 1. Piping Tanks forming part of the hydraulic system are to be 1.1 The design and setting of safety valves shall fitted with oil level indicators. be such that their response threshold does not allow The lowest permissible oil level is to be monitored. the maximum allowable working pressure to be ex- Audible and visual alarms shall be given on the navi- ceeded by more than 10 %. gating bridge and in the machinery space. The alarms on the navigating bridge shall be individual alarms. 1.2 Pipes are to be installed at a sufficient dis- tance from the ship's shell. As far as possible, pipes In power-operated hydraulic steering systems, an should not pass through cargo spaces. Pipe flange additional permanently installed storage tank is to be connections are not permitted in the vicinity of elec- fitted which has a capacity sufficient to refill at least trical equipment or connections. one of the control systems including the service tank. Chapter 2 Section 7b G Azimuthing Propulsors III - Part 1 Page 7b–10 GL 2012

This storage tank is to be permanently connected by Sensors, essential for the operation and mounted in pipes to the control systems so that the latter can be non-accessible areas, have to be designed as double recharged from a position inside the steering com- sensors and are to be independently redundant. The partment. independent redundancy is fulfilled, if another sensor measures a different but directly dependent parame- ters for measurement. A check of plausible signals has to be realised,, Illogical signals have to be G. Electrical Installations alarmed. 1. Sensors and automation 1.1 Sensors have to be of type approved design 1.2 Alarms and indicators are summarized in and self checking, as far as applicable. Table 7b.2. Level sensors should give a signal independent from The following table summarises the necessary sen- the kind of liquid, which is involved in the respective sors and alarms as given in the text above. The table system. Sensors showing levels of certain liquids is in addition to necessary sensors and alarms, which only are not allowed, except, where explicitly re- have normally to be applied, see also the GL Rules quested. Level sensors should give a signal safely in for Ship Operation and Auxiliary Systems (III-1-3b) both directions. and IEC 60092-501.

Table 7b.2 Alarms and indicators

Description Applicable for Parameter Kind of Information L = Low pods only information transfer I = Indication H = High S = Shut-down HH = High High A = Alarm Propulsion motor: Electromotor with closed air system X Humidity I Display (C.4.) Closed circuit cooling X Temperature H (E.3.) Flow I Gears: Lubrication oil Temperature H (C.5.2) Pressure L Lubrication oil tank Min + max level L H (C.5.2) Shafting: (Wear) Accelerations I Metal particles Shaft bearings X detection (C.6.2) I (oil samples or online sensor) Temperature H Alarm, two stage Lubrication of shafting: Redundant lubrication oil pump Flow I in two stages Display (C.6.2.3) X Switching over I Display Temperature H Alarm Lubrication oil L-Alarm / H- (C.6.2.3) Min + max level L + H Display

III - Part 1 Section 7b G Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–11

Table 7b.2 Alarms and indicators (continued)

Description Applicable for Parameter Kind of Information L = Low pods only information transfer I = Indication H = High S = Shut-down HH = High High A = Alarm Shaft sealing: (C.6.3) Header tank Min + max level L + H Alarm Any leakage Leakage H Alarm Emergency sealing device X operability I Alarm (if fault) Shaft movement: Locking device for propeller shaft Engagement I Display (C.6.4.1) Clutch for power transmission Engagement I Display (C.6.4.2) Bilge system: (C.7.2) Liquid in gondola X Bilge level H HH Alarm, two stage Bilge level Liquid in gondola X L HH Alarm, S monitoring Alarm, two Liquid in motor X Bilge level H HH stage, S Steering device: Control components Failure I Alarm (D.7.2) Steering angle limitation Failure I Display (D.7.3) Hydraulic systems: Permissible oil level in tanks Level L H Display (F.5.) Electrical systems: Comparing of redundant parameters Missing for measurement I Display plausibility (G.1.1) Data transmission Signal fault I Display (G.1.4) Critical situations X Occurrence I Display (G.1.5) Fire alarm X Smoke detected I Display (G.2.2)

1.3 Safety systems stallations (III-1-3a), Section 9, B. have to be com- plied with analogously.

All signals leading to or requesting a shut-down or an essential emergency action shall be produced and 1.4 Data transmission (podded drives only) transferred independently from the operation and the alarm system. Within the approval process of the slip ring unit, a check of the data transmitting system has to be in- cluded. Special emphasis shall be put on the influ- The requirements of the GL Rules for Electrical In- ence of the special electromagnetic environment. Chapter 2 Section 7b H Azimuthing Propulsors III - Part 1 Page 7b–12 GL 2012

If signals are transferred via components of the slip 2.2 Testing of power units for propulsion or ring unit, those components have to be realised re- steering dundantly. A fault in a signal line has to be alarmed. 1.5 If for podded drives critical situations may 2.2.1 The power units are required to undergo occur, they have to be indicated by a two stage alarm. tests on a test stand in the manufacturer's works. The crew shall be enabled to identify the problem and to take actions. For diesel engines see Section 3.

2. Further requirements For electric motors see GL Rules for Electrical Instal- 2.1 For further requirements of the electrical lations (III-1-3a), Section 14. installations see the GL Rules for Electrical Installa- tions (III-1-3a), Section 13. 2.2.2 For hydraulic pumps and motors, the GL Guidelines for the Design, Construction and Testing 2.2 Fire alarm (podded drives only) of Pumps (VI-5-1), are to be applied analogously. The area above the slip ring unit and accessible areas Where the drive power is 50 kW or more, this testing have to be equipped with smoke detectors. is to be carried out in the presence of a GL Surveyor. 2.3 Accessible areas Accessible areas, normally used for maintenance 2.3 Pressure and tightness tests work, have to be equipped with sufficient illumina- tion and ventilation. The access has to be locked to Pressure components are to undergo a pressure test. avoid any hazard to the staff.

The test pressure pp is

H. Testing and Trials pp = 1,5 ⋅ pe,zul

1. Quality assurance and inspection plan pe,zul = is the maximum allowable working pressure Testing and supervision have to be performed accord- [bar] = the pressure at which the relief ing to the quality assurance and inspection plan ap- valves open. However, for working pres- proved by GL. sures above 200 bar the test pressure need not exceed p + 100 bar 2. Testing and supervision during construc- tion For pressure testing of pipes, their valves and fittings, see the GL Rules for Ship Operation Installations and 2.1 Material certification and approval of Auxiliary Systems (III-1-4), Section 8. components The certification of the material for essential compo- Tightness tests are to be performed on components to nents and their inspection and testing are summarized which this is appropriate (e.g. gondola of a podded in Table 7b.3. drive).

Table 7b.3 Certification and approval of components

Certificate 2 1 Component, Assembly group Component, Special approval tests Material Final Steering foundation plate B B Ultrasonic test, true running test, Slewing bearing B A bearing tolerances Planetary gear for slewing motor B A Final testing and inspection Slewing gear A A Contact pattern, visual inspection Pipes and hoses see GL Rules for Hydraulic power pack Machinery Installations (I-1-2), – for steering motors A A Section 14, A. – C. – for CPP Function test, pressure test See GL Rules for Machinery Hydraulic motor Installations (I-1-2), Section 14, A. – A A Azimuthing drive C. Function test, pressure test

III - Part 1 Section 7b H Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–13

Table 7b.3 Certification and approval of components (continued)

Certificate 2 1 Component, Assembly group Component, Special approval tests Material Final Converter and power transmission See GL Rules for Electrical A A for azimuthing motor Installations (III-1-3a), Section 2, C. Electrical motor See GL Rules for Electrical A A Azimuthing drive Installations (III-1-3a), Section 14, B. Final inspection and functional test Azimuthing locking device B B GL Cone, well section and major housing Final inspection after heat treatment A metal plate A parts transmitting thrust and sand blasting: Pod cone complete with electrical A Final inspection by GL, FAT and hydraulic installation Visual inspection, pressure and raw casting: ultrasonic test Pod casing (gondola) A A After machining surface crack detection test and dimension protocol Slewing seal B A Same as stern tube seal Supervision during construction by GL, inspections to be agreed based on Electric propulsion motor, complete A A QA plan of maker, see GL Rules for Electrical Installations (III-1-3a), Section 14, B. Supervision construction by GL, Propulsor electric, inspections to be agreed based on QA transmission system, A A plan of maker, see GL Rules for slip ring (podded drive) Electric Installations (III-1-3a), Section 13 Gear parts, transmitting propulsion A A See Section 6 torque See GL Rules for Propulsion Plants Propeller shaft A A (III-1-2), Section 5 Shaft coupling A A Supervision of mounting by GL Manufacturer Inspection Certificate, Propeller shaft locking device B B functional test by GL Shaft (roller-)bearing + housing, etc. B B Manufacturer Inspection Certificate Propeller shaft seal B A Pressure test Propeller, controllable, build-up A A See Section 7a fixed pitch or monoblock Complete azimuthing propulsor A Functional and tightness test Auxiliary equipment See GL Rules for Ship Operation Pressure vessels A A Installations and Auxiliary Systems (III-1-4), Section 16 Emergency propeller shaft sealing See GL Rules for Propulsion Plant B A device (III-1-2), Section 5 Pipes and hoses see GL Rules for Machinery Installations (I-1-2), Hydraulic pipes and hoses B / A A Section 14, A. – C. Pressure test

Chapter 2 Section 7b H Azimuthing Propulsors III - Part 1 Page 7b–14 GL 2012

Table 7b.3 Certification and approval of components (continued)

Certificate 2 1 Component, Assembly group Component, Special approval tests Material Final Physical functional test in mounted Sensors Type approved condition (FAT) by GL Further components are to be tested and inspected as specified in the relevant GL Rules and to the satisfaction of the GL Surveyor!

1 as far as applicable for actual of azimuthing propulsor 2 according to the GL Rules for Principles and Test Procedures (II-1-1), Section 1, H. A: GL Material / Inspection Certificate, B: Manufacturer Material / Inspection Certificate

2.4 Final inspection and operational test 3.2 The faultless operation, smooth running and bearing temperatures of the gears and control system 2.4.1 After inspection of the individual compo- are to be checked during the sea trials under all nents and completion of assembly, azimuthing pro- steaming conditions. pulsors are to undergo a final inspection and opera- tional test at the manufacturer’s premises. The final 3.3 After the conclusion of the sea trials, the inspection is to be combined with a trial run lasting toothing is to be examined through the inspection several hours under part or full-load conditions. A openings and the contact pattern is to be checked. check of the tooth clearance and of the tooth contact The tooth contact pattern is to be assessed on the pattern is to be carried out, as far as applicable. basis of the reference values for the percentage area of contact given in Section 6, Table 6.6. 2.4.2 If no suitable test bed is available for the The scope of the check on contact pattern following operational and load testing of azimuthing propul- the sea trials may be limited with the Surveyor's sors, the tests can be carried out on the occasion of agreement provided that the checks on contact pattern the dock test or sea trials. called for in 2.4.1 and 2.4.2 have been satisfactory.

2.4.3 Limitations on the scope of the tests require 3.4 After successful sea trials the final motor GL's consent. parameters and all other relevant data of the podded drives have to be stamped on the podded drive poster. 3. Sea trials The power has to be calculated for the highest water and engine room temperature, based on the sea trial 3.1 The scope of sea trials for azimuthing and data. The calculation has to be submitted to GL for podded propulsors is defined in Table 7b.4. approval.

Table 7b.4 Scope of sea trials Test group/test Sub-test Test remarks 1. Slewing mechanism a) Testing of sensor for angle measurement in sea/ harbour mode b) Testing of switch over from sea to harbour mode Ship speed, rpm, steering and vice versa angle, etc. to be checked c) Testing of steering angle limitation (sea / Reductions: power, rpm harbour mode) and associated reductions d) Testing whether extreme, but possible Verification or correction of manoeuvres could endanger the ship or not limitations e) Testing of locking of steering drive and

emergency positioning Check of auxiliary drive, f) Testing of steering drive failure brake and overload clutch g) Wear down measurement of the slewing bearing As basic measurement

III - Part 1 Section 7b H Azimuthing Propulsors Chapter 2 GL 2012 Page 7b–15

Table 7b.4 Scope of sea trials (continued)

Test group/test Sub-test Test remarks 2. Steering manoeuvres Steering manoeuvres acc. to GL Rules for Ship Compare also SOLAS II-1, Operation Installations and Auxiliary Systems (III- Reg. 29 1-4), Section 2, B. 3. Run out test Check of ships course stability and down to which speed an inactive azimuthing propulsor can influence the course of the ship 4. Propeller shaft lock 5. Loss of propulsion of one pod 6. Crash stop a) Testing to fulfil requirements acc. to SOLAS b) Testing under adverse conditions Manual operation c) Testing of the automated procedure Only as far as applicable 7. Endurance test 8. Test of motor reversing 9. Manoeuvring tests GL Guidelines for Sea Trials according to GL Rules of Motor Vessels (VI-11-3) 10. Test of local control stations 11. Test of operational a) Measured and monitored data have to be Power, bearing temperature, condition monitoring recorded during the complete sea trials vibrations, etc. to be measured b) Quality of electrical current GL Rules for Electrical Installations (III-1-3a) c) Envelope of bearing vibrations Podded drives only

III - Part 1 Section 8 B Torsional Vibrations Chapter 2 GL 2012 Page 8–1

Section 8

Torsional Vibrations

A. General engine in form of tangential coefficients (for new/unconventional types of engines) 1. Scope – vibration damper The requirements of this Section apply to the compo- type, damping coefficient, moments of inertia, nents of the main shafting system and to essential dynamic stiffness equipment, compare Section 1, B.5. – elastic couplings These rules may be applied analogously for rudder type, damping coefficient, moments of inertia, propeller units driven by internal combustion engines. dynamic stiffness They are not applicable for electrically driven azi- muthing propulsors (fixed or turnable). – reduction/power intake off (PTO) gears type, moment of inertia for wheels and pinions, 2. Definitions individual gear’s ratios per mesh, effective stiff- ness 2.1 For the purposes of these Rules, torsional – shafting vibration stresses are additional loads due to torsional shaft diameter of crankshafts, intermediate vibrations. They result from the alternating torque shafts, gear shafts, thrust shafts and propeller which is superimposed on the mean torque. shafts 2.2 The speed range in which the plant can be – propeller operated continuously is the service speed range. It type, diameter, number of blades, pitch and covers the range between nmin (minimum speed) and expanded area ratio, moment of inertia in air, 1,05 nN (nominal speed). moment of inertia of entrained water (for Zero and full pitch for CP propellers) Output data/results: B. Calculation of Torsional Vibrations – natural frequencies

1. A torsional vibration analysis covering the with their relevant vibration forms (modes) torsional vibration stresses to be expected in the main shafting system including its branches is to be submit- – forced vibratory loads (torques or stresses) ted to GL for approval. To facilitate a smooth and estimated torsional vibration torques/shear efficient approval process they should be submitted stresses in all important elements of the system electronically via GLOBE 1. In specific cases and with particular reference to clearly defined reso- following prior agreement with GL they can also be nance speeds for the whole operating speed submitted in paper form in triplicate. range. The results shall include the synthesised values (vectorial sum over all harmonics) for the The following data shall be included in the analysis: torques/stresses. Input data: 2. The calculations are to be performed both for – equivalent torsional vibration system normal operation (uniform pressure distribution over comprising moments of inertia and inertialess all cylinders or small deviations in the pressure distri- torsional elasticities/stiffnesses for the complete bution e.g. ± 5 %) and misfiring operation (one cylin- system der without ignition, compression of the cylinder still – prime mover existing). engine type, rated power, rated speed, cycles per revolution, design (in line, V-type, etc.), number 3. Where the installation allows various opera- of cylinders, firing order, cylinder diameter, tion modes, the torsional vibration characteristics are stroke, stroke to connecting rod ratio, oscillating to be investigated for all possible modes, e.g. in instal- mass of one crank gear, excitation spectrum of lations fitted with controllable pitch propellers for zero and full pitch, with power take off gear integrated in –––––––––––––– the main gear or at the forward crankshaft end for 1 Detailed information about GLOBE submission can be found loaded and idling generator, with clutches for engaged on GL’s website www.gl-group.com/globe. and disengaged branches. Chapter 2 Section 8 C Torsional Vibrations III - Part 1 Page 8–2 GL 2012

4. The calculation of torsional vibrations shall where 0,9 ≤ λ ≤ 1,05 also include the stresses/torques resulting from the superimposition of several harmonics (synthesised τ1 2 τ2 = ± 1,7 ⋅ 6,0 ⋅ [N/mm ] (3a) values) so far relevant for the overall assessment of cK ⋅ cW the system, see also 1., output data. Alternatively and depending on the material and de- 5. If modifications are introduced into the sys- sign the following formula may be used instead (3a) tem which have a substantial effect on the torsional τ1 vibration characteristics, the calculation of the tor- τ=±2 1, 7 ⋅ (3b) sional vibrations is to be repeated and re-submitted for cK approval. d = shaft diameter [mm] 6. Where an electrical machine, e.g. static con- λ = speed ratio [–] verter controlled motors, can generate periodic excita- = n/n tion leading to relevant torsional vibration stresses in o the system as a whole, this is to be taken into account n = speed [min–1] in the calculation of the forced torsional vibration. The manufacturer of the electrical machine is responsible no = nominal speed [min–1] for defining the excitation spectrum in a suitable man- R = tensile strength of shaft material [N/mm2] ner for performing forced torsional vibration calcula- m tions. cw = material factor [–] R160+ = m (4) 18 C. Permissible Torsional Vibration Stresses For the purpose of the formulas (1), (2), (3a), (3b) the tensile strength calculation value applied shall not Note: exceed the following limits: 2 Naval ships are commonly equipped with geared pro- Rm = 600 N/mm pulsion plants. For such plants the stresses in the – for propeller shafts in general shafting are in general irrelevant for design purposes. – for other shafts particularly intermediate The evaluation of the torsional behaviour should con- shafts, made of forged, low alloy carbon centrate on the torsional loading of crankshaft, gears or carbon manganese steel and flexible couplings. 2 Rm = 800 N/mm 1. Shafting – for all shafts except propeller shafts made of forged high alloy steels. Formula (3a) In no part of the shafting may the alternating torsional should be applied in conjunction with vibration stresses exceed the following values of τ for 1 such steels and special design features continuous operation or of τ2 under transient condi- only. tions. Fig. 8.1 indicates the τ1 and τ2 limits as a refer- ence for intermediate and propeller shafts of common cD = size factor [–] design and for the location deemed to be most se- = 0,35 + 0,93 · d–0,2 verely stressed (cK = 0,55 or cK = 0,45 for propeller c = form factor [–] shafts, and cK = 1,0 and cK = 0,8 for intermediate K shafts). The limits depend on the design and the loca- for intermediate and propeller shafts depend- tion considered and may in particular cases lie outside ing on details of design and construction of the indicated ranges according to Fig. 8.1. They are to applied mechanical joints in the shaft line. be determined in accordance with equations (1) - (4) The value of cK is given in Table 8.1. and Table 8.1.

Speed ranges in the n/no ≤ 0,8 area, in which the per- 2. Crankshafts missible values of τ1 for continuous operation are exceeded shall be crossed through quickly (barred 2.1 Crankshafts applied for engines for ships speed ranges for continuous operation), provided that classed by GL shall be approved on the basis of the the limit for transient operation τ2 is not exceeded. GL Calculation of Crankshafts for Internal Combus- tion Engines (VI-4-2). For application of this guide- 2 2 τ1 = ± cW ⋅ cK ⋅ cD ⋅ (3 − 2 ⋅ λ ) [N/mm ] (1) line a gas pressure distribution in the cylinder over the crank angle is submitted by the maker of the engine. for speed ration values λ < 0,9 The maker of the engine also applies for approval of a 2 maximal additional (vibratory) shear stress, which is τ1 = ± cW ⋅ cK ⋅ cD ⋅1,38 [N/mm ] (2) referred to the crank with the highest load due to mean III - Part 1 Section 8 C Torsional Vibrations Chapter 2 GL 2012 Page 8–3

torque and bending forces. Normally this approved This requirement does not apply to gear stages which additional shear stress may be applied for first evalua- run without load ( e.g. the idling stage of a reversing tion of the calculated vibratory stresses in the crank- gear or the idling gears of an unloaded shaft-driven shaft via the torsional vibration model. Common val- generator). These are covered by the provisions in ues are between 30 and 90 N/mm2 for medium and accordance to 3.4. high speed engines; but special confirmation of the value considered for judgement by GL is necessary. 3.4 In installations where parts of the gear train run without load, the torsional vibration torque in For further details see also Section 3, C.1. continuous operation shall not exceed 20 % of the nominal torque in order to avoid unacceptable stresses 2.2 When the generally approved limit for the due to gear hammering. This applies not only to gear vibratory stresses for the crankshaft of the engine as stages but also to parts which are particularly subject defined under 2.1 is exceeded, special considerations to torsional vibrations (e.g. multiple-disc clutch carri- may be applied to define a higher limit for the special ers). For loaded parts of the gear system the provisions investigated case. For this detailed system calculations in accordance to 3.1 apply. (combined axial / torsional model) and application of the actual calculated data within the model in accor- Higher alternating torques may be approved by GL if dance to the GL Guidelines for the Calculation of proof is submitted that measures have been introduced Crankshafts for Internal Combustion Engines (VI-4- considering these higher loadings see 3.1. 2), as quoted under 2.1 are necessary. 4. Flexible couplings 2.3 Torsional vibration dampers which are aim- ing to reduce the stresses in the crankshaft shall be 4.1 Flexible couplings shall be designed to with- suitable for use for diesel engines. GL reserve the stand the torsional vibration loads which occur in the right to call for proof of this, compare also F. operation of the ship. In this context, the total load Torsional vibration dampers shall be capable of being resulting, in accordance with B.4., from the superim- checked for performance ability in the assembled position of several orders is to be taken into account, condition or shall be capable of being dismounted see also Section 6. with reasonable ease for checking purposes. This requirement does not apply for small medium or high 4.2 Flexible couplings shall be capable to take in speed engines, so far the exchange of the damper is a higher alternating torque which can occur during de- part of the regular service of the engine and a fixed viation from normal operation according to B.2, dur- exchange interval is part of the engine’s crankshaft ing continuous operation within the service speed approval. range. Speed ranges within which, under abnormal operating 3. Gears conditions, continuous operation is not allowed shall be indicated in accordance with E.2. 3.1 In the service speed range 0,9 ≤ λ ≤ 1,05, no alternating torque higher than 30 % of the mean nomi- 5. Shaft-driven generators nal torque for this stage shall normally occur in any loaded gear’s mesh. In general the value for the 5.1 In installations with generators directly cou- maximum mean torque transmitted by the gear stage pled to the engine (free crankshaft end) it is necessary has to be applied for evaluation purposes as the mean to ensure that the accelerations do not exceed the nominal torque. values prescribed by the manufacturer in any part of If the gearing is demonstrably designed for a higher the generator. power, then, in agreement with GL, 30 % of the de- The applicable criterion in such cases shall be the sign torque of the concerned gear’s mesh may be tangential acceleration, which is the product of the applied as admissible. angular acceleration and the effective radius. The angular acceleration is determined by means of forced 3.2 When passing through resonant speeds below torsional vibrations calculations and is to be regarded the operational speed range during starting and stop- as the synthesised value of all major orders. However, ping of the plant, the alternating torque in the gear for marked points of resonance the value of the indi- shall not exceed twice the nominal mean torque for vidual harmonics may be used instead for assessment. which the gear has been designed.

3.3 Load reversal due to alternating torques is 5.2 The torsional vibration amplitude (angle) of normally permitted only while passing through the shaft-driven generators shall normally not exceed an lower speed range up to λ ≤ 0,35. electrical value of ± 5°. The electrical vibration ampli- tude is obtained by multiplying the mechanical vibra- If, in special cases, gear hammering within the opera- tion amplitude by the number of pole pairs. Whether tional speed range, is unavoidable, a barred speed GL is able to permit higher values depends on the range in accordance with E.1. is to due to be specified. configuration of the ship's electrical system. Fig. 8.1 Permissible torsional vibration stresses in shafting systems in accordance with formulas (1) – (3) (3) – (1) formulas with inaccordance systems shafting in stresses vibration torsional Permissible 8.1 Fig. Page 8–4 Chapter 2

2 2 t1, t2 [N/mm ] t1, t2 [N/mm ] 100 120 140 100 20 40 60 80 20 40 60 80 0 0 for shaft materials with atensile strength of450N/mm , , , , , 1,2 1,0 0,8 0,6 0,4 0,2 0 , , , , , 1,2 1,0 0,8 0,6 0,4 0,2 0 Section 8 Torsional Vibrations Vibrations Torsional 8 Section c d =700mm K =0,80 c d =700mm K =0,45 c d =700mm K C =0,45 t 1 c d =700mm K t =0,80 2 t 2 t 1 d =100mm c K =0,55 Speed ratio Speed ratio d =100mm c K =1,0 l l d =100mm c d =100mm c K K =0,55

=1,0

[-] [ -] 2

Propeller shafts Intermediate shafts III - Part 1 Part III - GL 2012

III - Part 1 Section 8 D Torsional Vibrations Chapter 2 GL 2012 Page 8–5

Table 8.1 Form factor cK for intermediate, thrust and propeller shafts

cK Shaft type/design

Intermediate shafts 1,00 with integral forged flanges and/or hydraulic oil mounted shrink fit couplings Intermediate shafts 0,60 with keyway/key flange connection (in general not to be used for plants with barred speed ranges) Intermediate shafts 0,50 with radial holes of standard design 1 (for example oil distribution (OD) shaft of CD plants) Intermediate shafts 0,30 with longitudinal slots of standard design 2 (for example for OD shaft of CP plants) Thrust shafts 0,85 transmitting thrust, additionally to the torque, by means of a collar (bending) Propeller shafts 0,80 in the fwd. propeller shaft area 3 within the stern tube Propeller shafts 0,55 with forged or hydraulic shrink fit flange and keyless propeller fit within the aft 4 propeller shaft area Propeller shafts 0,45 with key fitted propellers (in general not to be used for plants with barred speed ranges) and oil lubrication in the stern tube within the aft 4 propeller shaft area Propeller shafts 0,40 with grease lubrication in the stern tube in the aft 4 propeller shaft area

The part of propeller shafts outside the stern tube (engine room area) is subject to the same cK factors as the intermediate shaft. 1 The ck factor as given above covers the stress concentration for bores with good manufacturing quality and adequately smoothened up in the transitions for hole diameters not exceeding 30 % of the shaft's outer diameter. For other special designs individual stress concentration factors may be applied based on special considerations to be approved by GL. 2 The ck factor as given above covers the stress concentration for slots with good manufacturing quality and adequately smoothened up in the transitions for slots with axial extension less than 80 % of the shaft's outer diameter, width of the slot less than 10 % of the shaft's outer diameter and a rounding at the ends not less than the width of the slot (half circle). For other special designs or arrangements with more than one slot individual stress concentration factors may be applied based on special considerations to be approved by GL. 3 The fwd. propeller shaft area is the area inside the stem tube (up to the fwd. stern tube seal) next to the after bearing position as defined under 4. For designs with shaft bossings, the fwd. area is that adjoining and lying forward of the position of the aft bossing bearing. 4 The aft propeller shaft area is the area inside the stem tube extending from the aft stem tube bearing to the forward supporting edge of the propeller hub. For designs with shaft bossings, it is the area between the aft bossing bearing and the fwd. supporting edge of the propeller hub. The aft propeller shaft area is defined for an axial extent of at least 2,5 ⋅ d.

6. Connected units 6.2 In special critical cases, the calculations of forced torsional vibrations, including those for dis- 6.1 If further units, e.g. power turbines or com- turbed operation (dismounted unit), as stated in B.1. pressors, are coupled positively or non-positively to will be required to be submitted to GL. In such cases the main propulsion system, due attention is to be GL reserves the right to stipulate the performance of paid to these when establishing the torsional vibration confirmatory measurements, see D., including such loadings. as related to disturbed operation.

In the assessment of their dynamic loads, the limits defined by the respective makers are to be considered in addition to the criteria as stated in 1. If these limits D. Torsional Vibration Measurements are exceeded, the units concerned are to be disen- gaged or prohibited ranges of operation in accordance 1. During the ship's sea trials, the torsional with E.1. are to be declared. Disengaging of these vibrations of the propulsion plant are to be measured units shall generally not lead to substantial overload- over the whole operating range. Measuring investiga- ing of the main system in terms of exceeding the τ2 tions shall cover the normal as well as the misfiring limit for shafting systems, the maximum torque for condition. Speed ranges, which have been declared as flexible couplings or similar low cycle criteria for barred speed ranges in accordance with E.1. for mis- other components. firing operation shall not be investigated by meas- Chapter 2 Section 8 F Torsional Vibrations III - Part 1 Page 8–6 GL 2012

urements, as far as these ranges are finally declared F. Auxiliary Machinery as "barred" on the base of reliable and approved cal- culations and adequately documented. 1. Essential auxiliary machinery such as diesel generators, bow thrusters and other units driven by Measurements are required by GL for all plants with internal combustion engines shall be designed in a a nominal torque exceeding 40 kNm. For other plants way that the service speed range is free of unaccept- not meeting this condition, GL reserve the right to able stresses due to torsional vibrations in accordance ask for measurements depending on the calculation with C. results. The requirement for measurements will be communicated to the yard/engine supplier with the 2. Generators approval letter for the torsional vibration calculation. Where measurements of identical propulsion plants 2.1 For diesel generator sets with a mechanical (specifically sister ships) are available, further tor- output of more than 150 kW torsional vibration cal- sional vibration measurements for repeat ships may, culations shall be submitted to GL for approval. The with the consent of GL, be dispensed with. investigations shall include natural frequencies as In case that the measuring results are not conclusive well as forced vibration calculations. The speed range enough in respect to the calculations, GL reserves the 90 % to 105 % of the nominal speed shall be investi- right to ask for further investigations or new approval gated under full load conditions (nominal excitation). of a revised and adapted calculation model. 2.2 For rigidly coupled generators (without 2. Where existing propulsion plants are modi- elastic coupling) the vibratory torque in the input part fied, GL reserves the right to require a renewed in- of the generator's shaft shall not exceed 250 % of the vestigation of the torsional vibration characteristics. nominal torque. For the purposes of these Rules nominal torque is the torque which can be calculated by applying the actual data of the diesel engine (nominal output / nominal speed).

E. Prohibited Ranges of Operation The compliance of the limit of 250 % within the speed range 90 % to 105 % of the nominal speed 1. Operating ranges, which due to the magni- shall be proven. The calculation for this speed range tude of the torsional vibration stresses and/or torques shall be carried out by using the excitation corre- may only be passed through quickly (transient opera- sponding to the nominal torque of the engine. tion), are to be indicated as prohibited ranges of op- Exceeding the limit of 250 % may be considered in eration by red marks on the tachometer or in some exceptional cases, provided that the generator's other suitable manner at the operating station. manufacturer has designed the generator for a higher dynamical torque. But also in such cases a highest In normal operation the speed range λ ≥ 0,8 is to be value of 300 % of the actual nominal torque of the set kept free of prohibited ranges of operation. as defined above shall not be exceeded. In specifying prohibited ranges of operation it has to be observed that the navigating and manoeuvring 3. Bow thruster functions are not severely restricted. The width of the barred speed range(s) is (are) to be selected in a way 3.1 For bow thrusters as well as for further es- that the stresses in the shafting do not exceed the sential auxiliary machinery driven by diesel engines permissible τ1 limit for continuous operation with an with a mechanical output higher than 150 kW, natural adequate allowance considering the inaccuracies of as well as forced torsional vibration calculations shall the tachometers and the speed setting devices. For be submitted to GL for approval. The torsional vibra- geared plants the barred speed ranges, if any, refer to tion calculation shall focus on the real load profile of the gear meshes and elastic couplings and are to be the set. determined in the same way with reference to the permissible vibratory torques or permissible power 3.2 For bow thrusters as well as for further es- loss for these components (see also C.4. and C.5.). santial auxiliary machinery driven by electrical motor the supplier shall take care that relevant excitation 2. Measures necessary to avoid overloading of forces (e.g. propeller blade frequency or similar), the propulsion plant under abnormal operating condi- may not lead to unacceptable torsional vibration tions are to be displayed on instruction plates to be loadings. In special cases GL may require the sub- affixed to all engine control stations. mission of corresponding calculations. III - Part 1 Section 9 B Machinery for Ships with Ice Classes Chapter 2 GL 2012 Page 9–1

Section 9

Machinery for Ships with Ice Classes

A. General lae and factors specified in Section 5, C.3., apply to the area of the aft stern tube bearing or shaft bracket 1. Notation E affixed to the Character of bearing from the forward end of the propeller cone or Classification the aft propeller shaft coupling flange subject to a minimum axial area of 2,5 ⋅ d. The machinery of naval ships strengthened for naviga- tion in drift ice in the mouth of rivers and in coastal The diameter of the adjoining part of the propeller regions is designated after the Character of Classifica- shaft to the point where it leaves the stern tube may be tion by the additional Notation E, provided that the designed with an ice class reinforcement factor 15 % rules in B. are satisfied. less than that calculated by formula (2). The portion of the propeller shaft located forward of 2. Measures for other conditions of naviga- the stern tube can be regarded as an intermediate shaft. tion in ice Intermediate and thrust shafts do not need to be strengthened. 2.1 The requirements for ice classes E1, E2, E3 and E4 are equivalent to the relevant Finnish-Swedish 2.2 Reinforcements ice classes IC, IB, IA and IA super and are defined in the GL Rules for Machinery Installations (I-1-2), dE = CEW ⋅ d (1) Section 13. dE = increased diameter of propeller shaft [mm] 2.2 Class Notations PC1 to PC7 for polar class d = shaft diameter [mm] according to Section 5, ships may be assigned if the requirements which are C.3. defined in the GL Guidelines for the Construction of Polar Class Ships (I-1-22) are fulfilled. CEW = ice class strengthening factor [–]

85 ⋅ m 2.3 The additional requirements for special deck = c ⋅ 3 1 + ≥ 1,0 (2) and machinery equipment necessary for operation in 0,6 0,2 Pw ⋅ n 2 ice are defined in the GL Rules for Ship Operation Installations and Auxiliary Systems (III-1-4), Section 19. Ships meeting these requirements may be assigned PW = main engine power [kW] the Class Notation ICEOPS affixed to their Character n = propeller shaft speed [min-1] of Classification. 2

mice = ice class factor [–] according to Table 9.1 2.4 Measures for conditions of navigation in ice, different from the conditions relevant for 1., and 2.1 to c = 0,7 for shrink fits in gears [–] 2.3 may be agreed with GL case by case. = 0,71 for the propeller shafts of fixed-pitch propellers = 0,78 for the propeller shafts of controllable B. Requirements for Notation E pitch propellers 1. Necessary Propulsion Power In the case of ducted propellers, the values of c can be reduced by 10 %. The rated output of the main engines in accordance with Section 3, A.3. shall be such to cover the power Table 9.1 Value of ice class factor m demand of the propulsion plant for the ice class condi- ice tions under consideration and for continuous service. Ice class E

2. Propeller shafts, intermediate shafts, mice 8 thrust shafts

2.1 General 3. Shrunk joints The necessary propeller shaft reinforcements in accor- When designing shrink fits in the shafting system and dance with formula (1), in conjunction with the formu- in gearboxes, the necessary pressure per unit area Chapter 2 Section 9 B Machinery for Ships with Ice Classes III - Part 1 Page 9–2 GL 2012

2 pE [N/mm ] is to be calculated in accordance with the In case of ducted propellers, the values of f may be following formula (3). reduced by 15 %. z = number of blades [–] 22 2 6 22 Θ⋅Tfc + ⋅( Ae ⋅ c ⋅ QT +) −Θ⋅ T P = (3) mice, PW, n2 see 2.2. E Af⋅ CDyn = dynamic factor [–] in accordance with Sec- T has to be introduced as positive value, if the propel- tion 7a, formula (3) ler thrust increases the surface pressure at the taper. Change of direction of the axial force is to be ne- 4.2.2 Blade tips glected as far as performance and thrust are essentially less. 500 t1,0E = ⋅⋅+()0,002 D t ' (8) T has to be introduced as negative value, if the axial Cw force reduces the surface pressure of the taper, e.g. for tractor propellers. t1,0E = strengthened blade tip [mm]

⎛⎞μ0 2 t' = increase in thickness [mm] f[]=−θ−⎜⎟ (4) ⎝⎠S = 10 for ice class E cA = see Section 5 D = propeller diameter [mm] 2 ce = 0,89 ⋅ CEW ≥ 1,0 (5) Cw = material factor [N/mm ] in accordance with Section 7a, C.1., Table 7a.1 CEW = to be calculated according to 2.2 the higher value of the connected shaft ends has to be In case of ducted propellers, the thickness of the blade taken for the coupling tips may be reduced by 15 %. Other symbols in accordance with Section 5, D.4. 4.2.3 Leading and trailing edges

4. Propellers For ice class E the thickness of the leading and trailing edges of solid propellers and the thickness of the lead- 4.1 General ing edge of controllable pitch propellers shall be equal to at least 35 % of the blade tip t1,0E when measured at The propellers of ships with ice class E shall be made a distance of 1,25 ⋅ t from the edge of the blade. of the cast copper alloys or cast steel alloys specified 1,0E in Section 7a. For ducted propellers, the strengthening at the leading and trailing edges has to be based on the non-reduced 4.2 Strengthening tip thickness according to formula (8).

4.2.1 Blade sections 4.2.4 Blade wear

tCtEEP=⋅ (6) If the actual thickness in service is below 50 % at the blade tip or 90 % at other radii of the values obtained tE = increased thickness of blade section [mm] from 4.2.1 and 4.2.2, respective counter measures t = blade section thickness [mm] in accordance have to be taken. Ice strengthening factors according with Section 7a, C.2. to 4.2.1 and 4.2.2 will not be influenced by an addi- tional allowance for abrasion. If CCEP≤ Dyn then Note tE = t If the propeller is subjected to substantial wear, e.g. If CEP > CDyn then abrasion in tidal flats, a wear allowance should be added to the blade thickness determined in order to CEP achieve an adequate service time with respect to blade ttE =⋅ CDyn wear.

CEP = ice class strengthening factor [–] 4.2.5 Propeller mounting Where the propeller is mounted on the propeller shaft 21⋅⋅ z m = f1⋅+ice ≥ 1,0 (7) by the oil injection method, the necessary pressure per 0,6 0,2 2 Pnw ⋅ 2 unit area pE [N/mm ] in the area of the mean taper diameter is to be determined by formula (9). f = 0,62 for solid propellers Θ22⋅ Tf(ccQT)+⋅222 ⋅ 6 ⋅ + −⋅ Θ T = 0,72 for controllable pitch propellers P = Ae (9) E Af⋅ III - Part 1 Section 9 B Machinery for Ships with Ice Classes Chapter 2 GL 2012 Page 9–3

T has to be introduced as positive value, if the propel- CEW = ice class reinforcement factor in accordance ler thrust increases the surface pressure at the taper. with formula (2) [–] Change of direction of the axial force is to be ne- glected as far as performance and thrust are essentially 5. Gears less. T has to be introduced as negative value, if the propel- 5.1 General ler thrust reduces the surface pressure of the taper, e.g. for tractor propellers. Gears in the main propulsion plant of ships with ice class E are not to be strengthened. ⎛⎞μ0 2 f[]=−θ−⎜⎟ (10) ⎝⎠S 6. Sea chests and discharge valves ce = ice class reinforcement factor [–] in accor- Sea chests and discharge valves are to be designed in dance with formula (5) accordance with GL Rules for Ship Operation Installa- tions and Auxiliary Systems (III-1-4), Section 8. Other symbols in accordance with Section 7a, C.1. In the case of flanged propellers, the required diameter 7. Steering gear dsE of the alignment pin is to be determined by apply- ing formula (11). The dimensional design of steering gear components is to take account of the rudderstock diameter speci- d = C 1,5 ⋅ d (11) fied in GL Rules for Hull Structures and Ship Equip- sE EW s ment (III-1-1), Section 12. dsE = reinforced root diameter of alignment pin [mm] 8. Electric propeller drive ds = diameter of alignment pin for attaching the Where electric propeller drives are used, the condi- propeller [mm] in accordance with Section 5, tions set out in GL Rules for Electrical Installations D.4.3. (III-1-3a), Section 13 are to be fulfilled.

III - Part 1 Section 10 B Spare Parts Chapter 2 GL 2012 Page 10–1

Section 10

Spare Parts

A. General Iceland, Spitsbergen and the Azores is ex- empted. 1. In order to be able to restore engine opera- tion and manoeuvring capacity to the ship in the RSA (50) (Coastal Service) event of damage at sea spare parts for the main drive This range of service is limited, in general, and the essential equipment (see Section 1, B.5.) are to trade along the coasts, provided that the to be carried on board every ship, together with the distance to the nearest port of refuge and the necessary tools. offshore distance do not exceed 50 nautical These requirements are considered to be complied miles. This applies also to trade within en- with if the range of spare parts corresponds to the closed seas, such as the Baltic Sea and wa- following Tables considering the extent of the actu- ters with similar seaway conditions. ally installed systems and components at the time of RSA (SW) (Sheltered Water Service) commissioning. This range of service is limited to trade in 2. Depending on the design and arrangement of shoals, bays, haffs and firths or similar wa- the engine plant, the intended service and operation ters where heavy seas do not occur. of the ship, and also the manufacturer's recommenda- tions, a different volume of spare parts may be agreed 1. Internal combustion engines between the Naval Administration and GL. For internal combustion engines, see Section 3, the Where the volume of spare parts is based on special volume of spare parts is defined in Tables 10.1 to arrangements between the Naval Administration and 10.3. GL, technical documentation is to be provided. 2. Gas turbines A list of the relevant spare parts is to be carried on board. For gas turbines see Section 4a, the volume of spare parts is defined in Table 10.4. 3. In the case of propulsion systems and essen- tial equipment which are not included in the follow- 3. Gears and thrust bearings ing tables, the requisite range of spare parts is to be For gears and thrust bearings in propulsion plants see established in each individual case between Naval Section 6, the volume of spare parts is defined in Administration, shipyard and GL. Table 10.5.

4. Air compressors for essential services B. Volume of Spare Parts For air compressors see the GL Rules for Ship Opera- tion Installations and Auxiliary Systems (III-1-4), The volume of spare parts in accordance with the Section 6, 12 and 18, the volume of spare parts is tables below is classified according to different defined in Table 10.6. ranges of service: 5. Pumps A = Unlimited range of service and RSA (200) For pumps see the GL Rules for Ship Operation In- B = All other ranges of service stallations and Auxiliary Systems (III-1-4), Section 8, the volume of spare parts is defined in Table 10.7. Explanations: RSA (200) (Restricted International Service) 6. Hydraulic systems For hydraulic systems see the GL Rules for Ship This range of service is limited, in general, Operation Installations and Auxiliary Systems (III-1- to trade along the coast, provided that the 4), Section 14, the volume of spare parts is defined in distance to the nearest port of refuge and the Table 10.8. offshore distance do not exceed 200 nautical miles. This applies also to trade in the North 7. Other spare parts Sea and within enclosed seas, such as the Mediterranean, the Black Sea and waters For other spare parts for main and auxiliary engines with similar seaway conditions. Trade to the volume is defined in. Table 10.9. Chapter 2 Section 10 B Spare Parts III - Part 1 Page 10–2 GL 2012

Table 10.1 Spare parts for main engines 1, 4, 5, 6 Range of spare parts A B Main bearings or shells for one bearing of each size and type fitted, Main bearings 1 complete with shims, bolts and nuts Main thrust block Pads for “ahead” face of Michell type thrust block, or complete 1 set 1 set (integral) white metal thrust shoe of solid ring type 1 1 Bottom end bearings or shell of each size and type fitted, complete 1 set − with shims, bolts and nuts, for one cylinders Connecting rod bearings Trunk piston type: Gudgeon pin complete with bush/bearing shells and securing rings 1 set − for one cylinder Cylinder liner, complete, fully equipped and ready for installation Cylinder liner 1 − incl. gaskets Cylinder cover, complete, fully equipped and ready for installation, 1 − Cylinder cover including gaskets Cylinder cover bolts and nuts, for one cylinder ¼ set − Exhaust valves, with full equipment and ready for installation, for 1 set 1 set one cylinder Inlet valves, with full equipment and ready for installation, for one 1 set 1 set cylinder Valves Starting air valve, with full equipment and ready for installation 1 1 Overpressure control valve, complete 1 1 Fuel injection valves of each type, ready for installation, for one 1 set ¼ set engine 2 Hydraulic valve High-pressure pipe/hose of each type 1 − drive Piston: Piston of each type, ready for fitting, with piston rings, gudgeon 1 − Trunk piston type pin, connecting rod, bolts and nuts Piston rings Piston rings for one cylinder 1 set − Piston cooling Articulated or telescopic cooling pipes and fittings for one cylinder 1 set − Scope of spare parts to be defined with regard to lubricator design Cylinder lubricator 1 − and subject to approval Fuel injection pump complete or, when replacement of individual Fuel injection components at sea is practicable, complete pump element with 1 − pumps associated valves, seals, springs, etc. or higher pressure fuel pump High pressure fuel pipe of each size and shape fitted, complete with Fuel injections pipes 1 − couplings Auxiliary blower, complete including drive 1 − Exhaust-gas turbocharger: rotor complete with bearings, nozzle Charge air system 3 1 set − rings and attached lube oil pump Suction and pressure valves of each type for one cylinder 1 set − Gaskets and Special gaskets and packings of each type for cylinder covers and − 1 set packings cylinder liners, for one cylinder Exhaust gas system Compensator of each type 1 − (engine-related)

III - Part 1 Section 10 B Spare Parts Chapter 2 GL 2012 Page 10–3

Tabelle 10.1 Spare parts for main engines 1, 4, 5, 6 (continued)

1 in the case of multi-engine installations, the minimum required spares are only necessary for one engine 2 a) engines with one or two fuel-injection valves per cylinder: one set of fuel valves, complete b) engines with more than two fuel injection valves per cylinder: two valves complete per cylinder plus a corresponding number of valve parts (excluding the valve bodies) which make it possible to form a complete spare set by re-using the operational parts of the dismantled valves 3 spare parts for exhaust-gas turbocharger and auxiliary blower may be omitted if emergency operation of the main engine after failure is demonstrably possible The requisite blanking, bypass and blocking arrangements for the emergency operation of the main engine are to be available on board. 4 the necessary tools and equipment for fitting the required spare parts are to be available on board 5 spare parts are to be replaced immediately as soon as they are “used-up” 6 For electronically controlled engines spare parts as recommended by the engine manufacturer are to be provided.

Table 10.2 Spare parts for auxiliary engines driving electric generators for essential equipment

Range of spare parts A Bearings or shells for one bearing of each size and type fitted, complete with Main bearings 1 shims, bolts and nuts Exhaust valves, complete with casings, seats, springs and other fittings for one 2 sets cylinder Inlet valves, complete with casings, seats, springs and other fittings for one cylin- 1 set Valves der Starting air valve, complete with casing, seat, springs and other fittings 1 Overpressure control valve, complete 1 Fuel valves of each size and type fitted, complete, with all fittings, for one engine 1/4 set Connecting rod Bottom end bearings or shells of each type, complete with all fittings 1 bearings Gudgeon pin with bush for one cylinder 1 Piston rings Piston rings, for one cylinder 1 set Fuel injection pump complete or, when replacement of individual components at Fuel injection sea is practicable, complete pump element with associated valves, seals, springs, 1 pumps etc. or equivalent high pressure fuel pump Fuel injection High pressure fuel pipe of each size and shape fitted, complete with fittings 1 pipes Gasket and Special gaskets and packings of each size and type fitted, for cylinder covers and 1 set packings cylinder liners for one cylinder Note 1. Where the number of generating sets (including stand-by units) is greater than called for by the Rules, no spares are required for the auxiliary engines. 2. Where several diesel engines of the same type are installed by way of generator drive spare parts are re- quired for one engine only. 3. No spares are required for the engines driving emergency generator sets 4. For electronically controlled engines sp0are parts recommended by the engine manufacturer are to be pro- vided.

Chapter 2 Section 10 B Spare Parts III - Part 1 Page 10–4 GL 2012

Table 10.3 Spare parts for prime movers of essential equipment other than generators

Range of spare parts The range of spare parts required for auxiliary drive machinery for essential consumers is to be specified in accordance with Table 10.2 Note Where an additional unit is provided for the same purpose no spare parts are required.

Table 10.4 Spare parts for gas turbines

Range of spare parts For essential main propulsion: For each gas turbine a complete set of wear and tear parts, which can be changed on board by a crew without considerable maintenance expertise. For non-essential propulsion: No spare parts prescribed by GL. If applicable, to be defined by manufacturer. For driving of auxiliaries: For two gas turbines each one set of wear and tear parts, which can be changed on board by a crew without considerable maintenance expertise.

Table 10.5 Spare parts for gears and thrust bearings in propulsion plants

Range of spare parts A B

Wearing parts of gear-driven pump supplying lubricating oil to gears or one complete 1 set − lubricating oil pump if no stand-by pump is available 1 Thrust pads for ahead side of thrust bearings 1 set 1 set

Table 10.6 Spare parts for air compressors for essential services

Range of spare parts A B Piston ring of each type and type fitted for one piston 1 set 1 set Suction and delivery valves complete of each size and type ½ set ½ set Note For spare parts for refrigerant compressors, see Chapter 4, Section 12, K.

Table 10.7 Spare parts for pumps

Range of spare parts A B Valve with seats and springs each size fitted 1 set 1 set

Piston rings each type and size for one piston 1 set 1 set Piston pumps Bearing of each type and size 1 1 Centrifugal Rotor sealings of each type and size 1 1 pumps Gear and screw Bearings of each type and size 1 1 type pumps Rotor sealings of each type and size 1 1 Note Where, for a system a stand-by pump of sufficient capacity is available, the spare parts may be dispensed.

III - Part 1 Section 10 B Spare Parts Chapter 2 GL 2012 Page 10–5

Table 10.8 Spare parts for hydraulic systems

Range of spare parts A B Pressure hoses and flexible pipes, at least one of each size 20 % 20 % Seals, gaskets 1 set 1 set Note For seals, this requirement is applicable only to the extent that these parts can be changed with the means available on board. Where a hydraulic system comprises two mutually independent sub-systems, spare parts need to be supplied for one sub-system only.

Table 10.9 Other spare parts

Range of spare parts A B Safety valve or one valve cone and spring of each type for pressure vessels 1 1 Hoses and compensators 20 % 20 % Testing device for fuel injection valves 1 1 Note For carrying out maintenance and repair work, a sufficient number of suitable tools and special tools according to the size of the machinery installation is to be available on board.

III - Part 1 Section 11 B Special Requirements of the Naval Ship Code Chapter 2 GL 2012 Page 11–1

Section 11

Special Requirements of the Naval Ship Code

A. General 1.2 Performance requirement The performance requirements 2 – 14 are met in a 1. An Introduction to the Naval Ship Code very wide extent if the requirements in all the Chap- (NSC) is contained in the GL Rules Classification and ters and Sections of the GL Naval Rules are strictly Surveys (III-0), Section 8. considered.

2. The performance requirements of Chapter IV 2. Concept of Operations – Engineering Systems of the Naval Ship Code and (Regulation IV, 2) the adequate technical solutions of Germanischer Lloyd (GL) are summarized in the following. The Concept of Operations Statement (ConOps) is specified in the GL Rules for Classification and Surveys (III-0), Section 8, E. where also the required forms are included as Annex A to this Section. B. Performance Requirements of Chapter IV 3. Provision of Operational Information For the subject of this Chapter the main requirements (Regulation IV, 3) of Chapter IV – Engineering Systems of the Naval Ship Code concerning main propulsion can be summa- 3.1 Operators shall be provided with adequate rized as follows: information and instructions for the safe operation and maintenance of all machinery and systems. 0. Goal The general aspects of the documents which have to (Regulation IV, 0) be submitted for approval by GL are defined in The Engineering Systems shall be designed, con- Section 1, C. The detailed scope of documents is given structed, operated and maintained to: in the different Sections of this Chapter.

0.1 Minimise danger to embarked personnel in 4. Propulsion all foreseeable operating conditions. (Regulation IV, 4)

0.2 Provide high availability and minimise risk of 4.1 The propulsion machinery shall enable the mal-operation in all foreseeable operating conditions. ship to manoeuvre as and when required by the com- mand but still remain within the designed or imposed 0.3 Ensure the watertight and weathertight integ- limitations. rity of the hull. Main engines and essential equipment shall be pro- 0.4 Enable the restarting of shut-down systems vided with effective means of control. The require- and equipment necessary to provide essential safety ments for such machinery control and monitoring functions (“dead ship” starting) without external aid. installations are defined in the GL Rules for Electrical Installations (III-1-3a), Section 9, B. 0.5 Provide support to the embarked personnel and provide essential safety functions in the event of 4.2 To enable the ship to manoeuvre, this regula- all foreseeable damage at least until the crew have tion shall be applied with Regulation 5, Manoeuvring. reached a place of safety or the threat has receded. See 5. These goals are met by numerous detailed measures defined in this Chapter. 4.3 Redundancy of propulsion equipment shall be provided. The Naval Administration shall give consid- 1. General eration of the reliability of single essential propulsion (Regulation IV, 1) components on application.

1.1 Definitions In general naval ships shall be equipped with two propulsors, compare Section 7b, C.1. If, in exceptional As far as possible a part of the definitions have to be cases, the application of only one propulsor is in- incorporated to the GL Naval Rules, e.g. designation tended, proof of sufficient redundancy has to be deliv- of lighting. ered by a Failure Mode and Effect Analysis (FMEA). Chapter 2 Section 11 B Special Requirements of the Naval Ship Code III - Part 1 Page 11–2 GL 2012

For special requirements on redundant propulsion the this Chapter. Details of the design of electrically oper- conditions of the Class Notation RP1, RP2 or RP3 ated transmission, signalling and alarm systems are may be introduced in the design, compare Section 2, specified in the GL Rules for Electrical Installations K. (III-1-3a), Section 9, C.

4.4 The propulsion equipment and systems shall 4.9 Means shall be provided whereby normal be designed, constructed and maintained to minimise operation of propulsion machinery can be sustained danger to personnel aboard in all foreseeable operat- or restored even though an auxiliary system of an ing conditions. essential safety function becomes inoperative. In all Sections of this Chapter a very great number of All essential safety functions are designed redun- detailed measures to ensure personal safety is speci- dantly; compare the different Sections of Chapters 3a, fied. 3b and 4.

4.5 Essential safety functions shall be continu- 4.10 Means shall be provided to ensure that the ously available or recoverable without compromising propulsion machinery can be brought into operation the safety of the ship following a single operational from the dead ship condition without external aid. action or system/equipment fault. For the unlikely situation that a dead ship condition The one failure principle is a basic design assumption occurs for naval ships with several electrical power for GL Naval Rules, see Section 1, A.8.10. generation plants, the ship has to be equipped with mobile units to generate a basic electrical energy 4.6 The design, construction, installation and and/or compressed air demand for starting auxiliary operation of propulsion equipment shall not cause machinery. For detailed requirements see the GL interference or excessive forces that could lead to its Rules for Ship Operation Installations and Auxiliary failure or failure of other equipment and systems. Systems (III-1-4), Section 6, A.4. The rudder angle in normal service is to be limited by If the naval ship has the Class Notation NSC (IV) devices fitted to the steering gear to a rudder angle of assigned and shall be equipped with an emergency 35° at both sides, compare the GL Rules for Ship generator unit it can be used for starting first auxiliary Operation Installations and Auxiliary Systems (III-1- machinery and secondary the main engines. The re- 4), Section 2, B.3.5. Deviations are only permitted quirements for such a system are specified in the GL with consent of GL. Rules for Electrical Installations (III-1-3a), Section 19, B.4. See also 4.8. Power operated steering device systems are to be fitted with overload protection. Manoeuvres possibly 4.11 Fuel supply arrangements are to be such that conflicting with the design features of the propulsor or adequate reserve of fuel is available without continu- the ship have to be blocked by automatic control, ous transfer of fuel and that means are provided to compare Section 7b, D.2. ensure that this reserve is of a suitable quality for use. The Naval Administration may impose additional The size of fuel service tanks depends on the assigned requirements for the reduction of vibration for opera- Class Notation for Automation and the defined time tional reasons. period in which the machinery space is left unat- In Section 1, D.2. it is defined how vibrations for tended, compare the GL Rules for Automation (III-1- machinery, equipment and hull structures are to be 3b), Section 2. The Naval Administration may decide taken into account by calculation proofs and meas- if during this period automatic topping up of these urements. The areas of assessment of vibration load tanks shall be arranged or not. In any way a reserve are specified in Section 1, Fig. 1.1. capacity of 15 % is required by GL. The fuel has to pass filters – and if necessary a purifier 4.7 The requirements for manoeuvrability as – in the delivery lines of the fuel pumps as defined in required by Chapter III Regulation 5 Safety of Em- the GL Rules for Ship Operation Installations and barked Persons, paragraph 10, 11 and 12 apply in Auxiliary Systems (III-1-4), Section 8, G.7 and G.8. addition to the requirements. See GL Rules for Hull Structures and Ship Equipment 5. Manoeuvring (III-1-1), Section 24, C.5. controllability and the com- (Regulation IV, 5) ments specified there. 5.1 The manoeuvring equipment shall enable the 4.8 Effective means of communicating orders ship to manoeuvre as and when required by the com- from the normal and emergency conning positions to mand but still remain within the designed or imposed any position from which the speed and direction of limitations. thrust of the propellers can be controlled shall be provided. Manoeuvring equipment shall be provided with effec- tive means of control. The requirements for such ma- The required communication and signalling equipment chinery control and monitoring installations are de- for the propulsion plant is defined in Section 2, J. of fined in the GL Rules for Electrical Installations (III- III - Part 1 Section 11 B Special Requirements of the Naval Ship Code Chapter 2 GL 2012 Page 11–3

1-3a), Section 9, B. For rudders stoppers at the end 5.7 The manoeuvring equipment control system positions of tillers and quadrants are to be provided, shall exhibit sufficient redundancy to cope with single respectively for hydraulic steering gears also limiting failures of components and electrical supply. devices to be fitted within the rudder actuator, com- pare the GL Rules for Ship Operation Installations and Open loop control for speed and power of internal Auxiliary Systems (III-1-4), Section 2, B.3.6. For combustion engines are subject to mandatory type azimuthing propulsors the failure of the steering angle approval. limitation has to be alarmed. For further details see Section 7b, D.7. 5.8 Effective means of communicating orders 5.2 Machinery and systems required for manoeu- from the normal and emergency conning positions to vring shall meet the relevant requirements of Chapter any position from which the speed and direction of III Regulation 5 Safety of Embarked Persons. thrust of the propellers can be controlled shall be provided. See GL Rules for Hull Structures and Ship Equipment (III-1-1), Section 24, C.5 A voice communication system is to be provided be- tween bridge, radio room, machinery control centre, 5.3 The manoeuvring equipment system shall machinery rooms, steering gear compartment, combat exhibit sufficient redundancy to cope with single fail- information centre and damage control centre. This ures without the loss of manoeuvring capability. system shall also be operable in the event of the fail- Every naval ship has to be provided with at least one ure of the main power supply. For details see the GL main steering and one auxiliary steering gear. Both Rules for Electrical Installations (III-1-3a), Section 9, steering gears are to be independent of each other and, C.5. wherever possible, act separately on the rudder stock. For the detailed requirements concerning rudders see 5.9 The motive power supply shall exhibit a level the GL Rules for Ship Operation Installations and of redundancy, diversity and capacity to ensure that Auxiliary Systems (III-1-4), Section 2, B., concerning the manoeuvring equipment remains operational and azimuthing propulsors see Section 7b, D.7. shall exhibit a level of continuity to ensure continuous operation. 5.4 The possibility of mechanical locking due to a single failure shall be considered and accommodated. In general naval combat ships have at least two elec- Steering gear systems are to be equipped with a lock- trical power generation plants situated as far from ing system effective in all rudder positions, see the GL each other as possible for an actual ship design. From Rules for Ship Operation Installations and Auxiliary these plants a power distribution with interconnecting Systems (III-1-4), Section 2, B.3.7. For azimuthing feeder via main groups, groups and sub-groups is to be propulsors two steering devices are to be provided. In established and ensures a wide variety of redundant case of failure of the main steering device, the auxil- power supply to all kinds of essential systems and iary steering device has at least to be capable of mov- equipment. For details see the GL Rules for Electrical ing the propulsor to midship position, where the pro- Installations (III-1-3a), Section 4, H. pulsor can be locked by the locking mechanism. See Section 7b, D.5. If the Naval Administration wishes a design with an emergency generator and the Class Notation NSC 5.5 It shall be possible to operate the manoeu- (IV) is assigned, the requirements for such a system vring equipment from a number of locations to be are specified in the GL Rules for Electrical Installa- agreed with the Naval Administration. tions (III-1-3a), Section 19, B.4. Where controls are possible from several control sta- tions strict requirements for interlocks, taking over of This is to include provision of supplies and control in commands, etc. are to be observed, compare the GL the event of damage to the ship. Rules for Electrical Installations (III-1-3a), Section 9, B.3. The electrical power generating plants with several generator units have their own switchboard and are 5.6 The operational status of the manoeuvring located in different watertight compartments resp. equipment shall be clearly visible at each control different fire control zones. In case of an emergency station. generator the location of machinery room, switch- board room and fuel tank will be as high as possible Indicators for propeller shaft speed, direction of rota- above the watertight main deck to be available as long tion and propeller pitch, if applicable, are to provided as possible if the ship is damaged. at the bridge, compare the GL Rules for Automation (III-1-3b), Section 5, A.2. Also the rudder position has to be clearly indicated at the bridge and at all steering 5.10 Sufficient electrical protection measures shall stations, see GL Rules for Ship Operation Installations be provided to prevent machinery and control system and Auxiliary Systems (III-1-4), Section 2, B.3.11. damage. Chapter 2 Section 11 B Special Requirements of the Naval Ship Code III - Part 1 Page 11–4 GL 2012

All electrical systems have to include protective meas- Normally naval ships should have at least two azi- ures against foreign bodies and water, electric shock muthing propulsors. For azimuthing propulsors it is (direct and indirect contact), explosion, lightning and specified that a failure of a single element within con- electromagnetic energy. The detailed requirements for trol, and hydraulic/electrical systems of one propulsor such measures are defined in the GL Rules for unit shall not lead to a failure of another unit, compare Electrical Installations (III-1-3a), Section 1, J. Section 7b, D.7.

5.11 The manoeuvring equipment shall be fail safe and exhibit alternative modes of operation to fulfil the 5.12 Clear system diagrams and instructions shall manoeuvring requirements during a failure condition. be provided detailing the change over procedures andthe actions to be completed in the event of machin- Power operated steering gears are to be equipped with ery breakdown. two or more identical power units. In the event of failure of a single component means are to be pro- vided for quickly regaining control of one steering For all elements and systems of the propulsion and system, for details see the GL Rules for Ship Opera- manoeuvring plant a comprehensive documentation is tion Installations and Auxiliary Systems (III-1-4), to be submitted to GL as defined in the different Sec- Section 2, B. tions of this and the other Chapters of these Rules.