DNV-DS-E403: Standard for Surface Diving Systems
STANDARD DNV-DS-E403
Standard for Surface Diving Systems
JULY 2012
The electronic pdf version of this document found through http://www.dnv.com is the officially binding version
DET NORSKE VERITAS AS FOREWORD DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life, property and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification and consultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, and carries out research in relation to these functions. DNV service documents consist of among others the following types of documents: — Service Specifications. Procedural requirements. — Standards. Technical requirements. — Recommended Practices. Guidance. The Standards and Recommended Practices are offered within the following areas: A) Qualification, Quality and Safety Methodology B) Materials Technology C) Structures D) Systems E) Special Facilities F) Pipelines and Risers G) Asset Operation H) Marine Operations J) Cleaner Energy O) Subsea Systems
© Det Norske Veritas AS July 2012
Any comments may be sent by e-mail to [email protected]
This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document, and is believed to reflect the best of contemporary technology. The use of this document by others than DNV is at the user's sole risk. DNV does not accept any liability or responsibility for loss or damages resulting from any use of this document. DNV Standard DNV-DS-E403, July 2012 Changes – Page 3
CHANGES
General This is a new document, incorporating requirements previously found in DNV-OS-E402.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Contents – Page 4
CONTENTS
Sec. 1 General ...... 9 A. Introduction...... 9 A 100 Objectives ...... 9 A 200 Scope...... 9 A 300 Application...... 9 A 400 Relation to other DNV rules and other codes and standards ...... 10 A 500 Procedural ...... 10 A 600 Documentation...... 10 A 700 Survey and testing requirements during and after manufacture and assembly...... 10 A 800 Survey and testing requirements during and after installation...... 10 A 900 Marking and signboards...... 10 A 1000 Materials ...... 10 B. References...... 10 B 100 Normative references...... 10 B 200 Informative references ...... 12 B 300 Terminology and definitions...... 12 B 400 Terminology and definitions (continued) ...... 17 B 500 Abbreviations and symbols (guidance)...... 19 C. Procedural Requirements ...... 20 C 100 Certification and approval requirements...... 20 Sec. 2 Design Philosophy and Premises – SURFACE Diving Systems...... 21 A. Introduction...... 21 A 100 Objectives ...... 21 A 200 Scope...... 21 A 300 Application...... 21 A 400 References...... 21 A 500 Procedural requirements, approval & certification...... 21 A 600 Documentation...... 21 A 700 Survey and testing requirements during and after manufacturing and assembly ...... 21 A 800 Survey and testing requirements during and after installation...... 21 A 900 Marking and signboards...... 22 A 1000 Materials ...... 22 B. Documentation...... 22 B 100 General...... 22 B 200 Documentation of arrangement...... 22 B 300 Documentation of installation...... 22 B 400 Documentation for systems in operation ...... 23 B 500 Documentation for systems in demobilisation...... 23 B 600 Filing of documentation...... 23 C. Safety Philosophy ...... 24 C 100 General...... 24 C 200 Safety objective...... 24 C 300 Systematic review ...... 24 C 400 Quality management systems ...... 24 C 500 Inspection and test plans ...... 24 D. SURFACE Diving System Philosophy...... 25 D 100 General...... 25 D 200 System integrity ...... 25 D 300 Essential services ...... 25 D 400 Emergency services ...... 25 D 500 Non-important services...... 26 D 600 Layout and arrangement of the SURFACE diving system...... 26 D 700 Wet-bell – if installed ...... 26 E. External and Internal Environmental Conditions...... 26 E 100 General...... 26 E 200 External operational conditions ...... 26 E 300 Internal operational conditions (Inner area)...... 27 E 400 Submerged components...... 28 F. Installation of diving system on support vessel or fixed structure...... 28 F 100 Location ...... 28
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F 200 Physical protection...... 29 F 300 Ventilation and lighting ...... 29 F 400 Electrical power supplies to the installed diving system ...... 29 F 500 Structural fire protection...... 29 Sec. 3 Pressure Vessels for Human Occupancy, Gas Storage and other Purposes...... 30 A. Introduction...... 30 A 100 Objectives ...... 30 A 200 Scope...... 30 A 300 Application...... 30 A 400 References...... 30 A 500 Procedural requirements, approval and certification ...... 31 A 600 Documentation...... 31 A 700 Survey and testing requirements during and after manufacture ...... 32 A 800 Survey and testing requirements during and after assembly ...... 32 A 900 Marking and signboards...... 32 A 1000 Materials ...... 33 B. General Principles for Design of Chambers ...... 33 B 100 General...... 33 B 200 Design loads...... 34 B 300 Foundations for pressure vessels for human occupancy and for gas storage ...... 34 B 400 Doors, hatches, windows, branches etc...... 34 C. Welded Pressure Vessels, Materials, Fabrication and Strength...... 36 C 100 Materials ...... 36 C 200 Fabrication ...... 36 C 300 Fabrication tolerances ...... 36 C 400 Structural analysis to determine strength...... 36 C 500 Strength of vessels subjected to external pressure...... 36 C 600 Flanges for windows...... 36 D. Gas Cylinders...... 37 D 100 General...... 37 D 200 Heat treatment...... 37 D 300 Tolerances and surface conditions...... 37 E. Acrylic Plastic Windows...... 37 E 100 General...... 37 E 200 Materials ...... 37 E 300 Manufacturers of cast material...... 37 E 400 Certification of cast material...... 37 E 500 Certification of windows ...... 38 E 600 Geometry and thickness...... 38 E 700 Fabrication ...... 38 E 800 In service inspection ...... 38 Sec. 4 Life Support Systems including PIPING, Hoses, Valves, Fittings, Compressors and Umbilicals ...... 39 A. Introduction...... 39 A 100 Objectives ...... 39 A 200 Scope...... 39 A 300 Application...... 39 A 400 References...... 39 A 500 Procedural requirements, approval and certification ...... 39 A 600 Documentation requirements...... 39 A 700 Survey and testing requirements during and after manufacture ...... 40 A 800 Survey and testing requirements during and after assembly ...... 41 A 900 Survey and testing requirements during and after installation...... 41 A 1000 Materials, including components for gases containing elevated oxygen levels ...... 41 B. Gas Storage ...... 42 B 100 Capacity ...... 42 B 200 Shut-off, pressure relief and drainage...... 42 C. Gas Distribution and Control System ...... 43 C 100 General...... 43 C 200 Control stands ...... 43 C 300 Basket and wet-bell (if wet-bell is employed) ...... 43 C 400 Chambers ...... 44 C 500 Stand-by diver at surface ...... 44 C 600 Nitrogen/oxygen mixing systems for direct supply for breathing ...... 44
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D. Diver’s Heating and Environmental Conditioning in Chambers...... 44 D 100 General...... 44 D 200 Heating of divers in the water...... 44 D 300 Heating and cooling of chambers ...... 45 D 400 Noise reduction...... 45 D 500 Gas circulation systems for chambers...... 45 D 600 Removal of carbon dioxide...... 45 E. Piping Systems...... 45 E 100 General...... 45 F. Hoses...... 46 F 100 General...... 46 G. Valves...... 46 G 100 Valve design ...... 46 G 200 Chamber valves...... 46 H. Fittings and Pipe Connections...... 47 H 100 Detachable connections ...... 47 I. Pressure Regulators...... 47 I 100 General...... 47 J. Compressors...... 47 J 100 General...... 47 K. Umbilicals ...... 47 K 100 General...... 47 K 200 Hoses...... 47 K 300 Electrical cables ...... 47 K 400 Sheathing ...... 47 K 500 Strength members ...... 47 Sec. 5 Electrical Systems...... 48 A. Introduction...... 48 A 100 Objectives ...... 48 A 200 Scope...... 48 A 300 Application...... 48 A 400 References...... 48 A 500 Procedural requirements, approval and certification ...... 48 A 600 Documentation...... 48 A 700 Survey and testing requirements during and after manufacture ...... 49 A 800 Survey and testing requirements during and after assembly ...... 49 A 900 Survey and testing requirements during and after installation...... 49 A 1000 Markings and signboards ...... 49 A 1100 Materials ...... 49 B. System Design...... 49 B 100 Design principles ...... 49 B 200 System voltages ...... 49 B 300 Main electric power supply system...... 50 B 400 System functionality and design...... 50 B 500 Emergency power supply system...... 50 B 600 Transitional source...... 51 B 700 Battery systems ...... 51 B 800 Electric power distribution...... 51 B 900 Lighting...... 51 B 1000 Vessel arrangement...... 51 C. Equipment in general ...... 51 C 100 General requirements...... 51 C 200 Environmental requirements...... 52 C 300 Termination and cable penetrations...... 52 C 400 Earthing...... 52 C 500 Insulation ...... 52 D. Miscellaneous Equipment...... 52 D 100 General...... 52 D 200 Lighting equipment – inner area...... 53 E. Cables...... 53 E 100 Application...... 53
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Sec. 6 Fire Prevention, Detection and Extinction...... 54 A. Introduction...... 54 A 100 Objective...... 54 A 200 Scope...... 54 A 300 Application...... 54 A 400 References...... 54 A 500 Procedural requirements, approval and certification ...... 54 A 600 Documentation requirements...... 54 A 700 Survey and testing requirements during and after manufacture ...... 54 A 800 Survey and testing requirements during and after assembly ...... 54 A 900 Survey and testing requirements during and after installation...... 54 A 1000 Markings and signboards ...... 55 A 1100 Materials ...... 55 B. Fire Protection...... 55 B 100 Arrangement ...... 55 C. Fire Detection and Alarm System...... 55 C 100 “Outer area” ...... 55 C 200 “Inner area”...... 55 C 300 Fault detection...... 56 D. Fire Extinguishing...... 56 D 100 “Outer area” ...... 56 D 200 “Inner area”...... 56 E. Miscellaneous Equipment...... 56 E 100 Breathing apparatus and fire-fighter's outfit ...... 56 E 200 Portable fire extinguishers ...... 57 Sec. 7 Launch and Recovery Systems (LARS) ...... 58 A. Introduction...... 58 A 100 Objectives ...... 58 A 200 Scope...... 58 A 300 Application...... 58 A 400 References...... 58 A 500 Procedural requirements, approval and certification ...... 58 A 600 Documentation...... 58 A 700 Survey and testing requirements during and after manufacture ...... 59 A 800 Survey and testing requirements during and after assembly ...... 59 A 900 Survey and testing requirements during and after installation...... 59 A 1000 Marking and signposts ...... 59 A 1100 Materials ...... 59 B. Design Principles ...... 59 B 100 General...... 59 B 200 Divers basket and wet-bell (when installed)...... 60 B 300 Function ...... 60 B 400 Recovery ...... 61 B 500 Power ...... 61 B 600 Umbilical ...... 62 C. Strength ...... 62 C 100 Design loads...... 62 C 200 Dimensions ...... 63 C 300 Foundations for launch and recovery systems and lifting appliances...... 63 Sec. 8 Instrumentation and Communication...... 64 A. Introduction...... 64 A 100 Objective...... 64 A 200 Scope...... 64 A 300 Application...... 64 A 400 References...... 64 A 500 Procedural requirements, approval and certification ...... 64 A 600 Documentation...... 64 A 700 Survey and testing requirements during and after manufacture ...... 64 A 800 Survey and testing requirements during and after assembly ...... 64 A 900 Survey and testing requirements during and after installation...... 64 A 1000 Markings and signboards ...... 65 A 1100 Materials ...... 65
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B. Instrumentation ...... 65 B 100 General...... 65 B 200 Power supply to control and monitoring systems...... 65 B 300 Monitoring and inspection during operation ...... 65 B 400 Pressure control system ...... 65 B 500 Control stands ...... 66 B 600 Pressure indicators in wet-bell and chambers...... 67 B 700 Oxygen and carbon dioxide analysing systems in wet-bell and chambers...... 67 B 800 Other gases...... 67 B 900 Automatic environmental control systems (if employed)...... 67 C. Communication...... 68 C 100 General...... 68 C 200 Visual observation of divers ...... 68 C 300 Voice communication systems ...... 68 Sec. 9 Evacuation Systems...... 69 A. Introduction...... 69 A 100 Objectives ...... 69 A 200 Scope...... 69 A 300 Application...... 69 A 400 References...... 69 A 500 Procedural requirements, approval and certification ...... 69 A 600 Documentation...... 69 A 700 Survey and testing requirements during and after manufacture ...... 69 A 800 Survey and testing requirements during and after assembly ...... 69 A 900 Survey and testing requirements during and after installation...... 69 A 1000 Marking and signboards...... 69 A 1100 Materials ...... 69 App. A Selection of Safety Objective ...... 70
A. Introduction...... 70 A 100 General principles (informative)...... 70 B. Trigger Questions...... 70 B 100 Overall safety objective ...... 70 B 200 Assessment of risk ...... 70 B 300 Technical innovation...... 71 B 400 Contractors’ experience ...... 71 B 500 Quality management systems ...... 71 C. Systematic Review/Analysis ...... 71 C 100 What to do and how? (informative)...... 71
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SECTION 1 GENERAL
A. Introduction A 100 Objectives 101 The objectives of this standard are to give criteria and guidance on design, fabrication, installation, testing and commissioning of SURFACE diving systems employing air or NITROX breathing medium. Procedural requirements for operation, maintenance, and re-qualification of diving systems are normally specified in the Classification rules but the technical requirements in this DNV standard do generally apply. 102 Further objectives of this standard are to: a) provide an internationally acceptable standard of safety for SURFACE diving systems by defining minimum requirements for the design, materials, fabrication, installation, testing, commissioning, operation, repair, and re-qualification b) serve as a technical reference document for classification and verification services c) serve as a technical reference document in contractual matters between purchaser and contractor d) serve as a guideline for designers, purchaser, and contractors. 103 The objectives of this section are to outline the functionality of the standard and the related codes, standards and recommended practices. 104 General guidance is provided as to the use and interpretation of the standard and text from IMO Code of Safety for Diving Systems, 1995 Resolution A.831 (19) is included for reference. In the IMO text, this code is referred to as “the Code”. 105 The text from IMO Code of Safety for Diving Systems, 1995 Resolution A.831 (19) is included as normative reference. A 200 Scope 201 The scope is defined in each section for the various disciplines and may refer to standards that apply to the discipline in general, such as for electrical systems. In these cases this DNV Standard (DS) only contains requirements that are particular to SURFACE diving systems, whereas the generic requirements are given in the referred rules, standard or code. The combined requirements shall then constitute the scope. 202 Requirements for the support vessels are given in DNV Rules for Classification of Ships Pt.5 Ch.16, such as the requirements for floatation and positioning ability. 203 Where the Code requires that a particular fitting, material, appliance, apparatus, item or type of equipment should be fitted or carried in a system, or that any particular provision should be made, or any procedure or arrangement complied with, the Administration may allow alternative arrangements in that system, provided that the Administration is satisfied that such alternatives are at least as effective as the requirements of the Code. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.5 Equivalents) The design of arrangements, systems and individual components may alternatively or supplementary to the Standard be based on recognized standards, codes, national regulations and other methods of safety and strength evaluation than specified in the Standard. The basis shall be equivalent to the requirements given in this Standard. 204 This section bears impact on all other sections. A 300 Application
301 DSV-SURFACE is normally restricted to dmax (= maximum depth) < 60 msw (= metres sea water) and Top (= operating time) < 8 hours. 302 This standard applies to SURFACE diving systems for any location. The SURFACE diving system may thus be located on and operated from a ship, barge, mobile offshore platform, fixed offshore installation or an onshore site, in the latter case for training, research purposes and such. However, the standard primarily applies to SURFACE diving systems used in the petroleum and natural gas industries. For application in other industries, special considerations may need to be agreed by the parties to the contract and or involved statutory regulators. 303 The SURFACE diving systems may be categorised as: a) SURFACE diving systems with deck decompression chambers and a ladder or basket for deployment of divers
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.1 – Page 10 b) for ‘wet-bell’ deployment of divers 304 This standard is not applicable to SCUBA diving, closed bell operations utilising submersible decompression chambers, Saturation diving systems, submersibles including atmospheric diving suits, submarines or submarine rescue systems. A 400 Relation to other DNV rules and other codes and standards 401 The requirements in this standard are based on requirements given in DNV Rules for Classification of Ships, and principles outlined in DNV Standards (see B). 402 Where reference is made to codes other than DNV documents, the valid revision shall be taken as the revision that was current at the date of issue of this standard. 403 In case of conflict between requirements of this standard and a reference document, the requirements of this standard shall prevail. 404 This standard is intended to comply, as far as reasonably possible, with the requirements given in IMO Code of Safety for Diving Systems, 1995 Resolution A.831 (19). 405 There are no known major deviations to the IMO Code of Safety for Diving Systems, 1995 Resolution A.831 (19) except those marked as non-applicable text. Guidance note: Additional requirements for the SURFACE diving system may be applicable due to the statutory requirements given in certain geographic areas, or onboard ships flying certain flags.
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A 500 Procedural 501 Procedural requirements are given under A500 in each relevant section. A 600 Documentation 601 Documentation requirements are given under A600 in each relevant section. A 700 Survey and testing requirements during and after manufacture and assembly 701 Survey and testing requirements during and after manufacture and assembly are given under A700 in each relevant section and in DNV-RP-E401 Survey of Diving Systems. A 800 Survey and testing requirements during and after installation 801 Survey and testing requirements during and after installation are given under A800 in each relevant section and in DNV-RP-E401 Survey of Diving Systems. A 900 Marking and signboards 901 Marking and signboard requirements are given under A900 in each relevant section. A 1000 Materials 1001 Material specifications and requirements are given under A1000 in each relevant section.
B. References B 100 Normative references 101 The latest revisions of the following Rules apply:
Table B1 DNV Rules Title DNV Rules for Classification of Ships 102 The latest revisions of the following DNV Service specifications apply:
Table B2 DNV Service Specifications Reference Title DNV-DSS-105 Rules for Certification and Verification of Diving Systems
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103 The latest revisions of the following DNV Standards apply:
Table B3 DNV Standards Reference Title DNV-OS-A101 Safety Principles and Arrangements 104 The latest revisions of the following DNV Recommended practices apply:
Table B4 DNV Recommended Practices Reference Title DNV-RP-A201 Plan Approval Documentation Types – Definitions 105 The latest revisions of the following DNV Standards for Certification and Classification notes apply:
Table B5 DNV Standards for Certification and Classification notes Title Standard for Certification No. 2.22 Lifting Appliances 106 The latest revisions of the following DNV Guidelines apply: (Empty) 107 The latest revisions of the following other references apply:
Table B6 Other normative references Reference Title ASME VIII Div.1 or Div. 2 1 ASME Boiler and Pressure Vessel Code ASME PVHO-1 Safety Standard for Pressure Vessels for Human Occupancy ASME PVHO-2 Safety Standard for Pressure Vessels for Human Occupancy in Service Guidelines for PVHO Acrylic Windows. ASTM G93 Standard Practice for Cleaning Methods and Cleanliness Levels for Materials and Equipment Used in Oxygen-Enriched Environments API Codes for hoses BS 5355 Specification for filling ratios and developed pressures for liquefiable and permanent gases. EN 738-1, -2 and -3 Pressure regulators for use with medical gases EN-1964-1 1 Transportable gas cylinders (part 1:1999, part 2:2001 or part 3:2000) EN 1968 Periodic Inspection and testing of Seamless gas cylinders EN ISO 11120 1 Gas cylinders - Refillable seamless steel tubes for compressed gas transport, of water capacity between 150 l and 3000 l - Design construction and testing (ISO 11120:1999): EN 13445 1 Unfired pressure vessels EN 1708-1 Welding - Basic weld joint details in steel IMO Code of Safety for Diving Systems, 1995 Resolution A.831(19), IMO MSC/Circ.645 of 6 June 1994 Guidelines for Vessels with dynamic positioning systems IMO Resolution A.809(19) In reference to SOLAS Regulation III/6.2.1 and III/6.2.2. IMO res. MSC.61(67) (FTP Code) IMO resolution A.468 (XII) Code on noise levels onboard ships. IEC No.79-10 International Electrotechnical Commission's Publication No.79-10, and IMO (MODU) Code chapter 6, ISO 6385 Ergonomic Principles in the Design of Work Systems ISO 9000 Guidance on the selection and use of quality systems, and ISO 10013 Guidance on developing quality manuals. ISO 10 380, BS6501 Flexible metallic hoses ISO 10474 Steel and Steel Products - Inspection Documents /EN 10204 Metallic Products - Types of Inspection Documents ISO 13628-5 “Petroleum and natural gas industries – Design and operation of subsea production systems – Part 5: Subsea control umbilicals” (NFPA) Codes National Fire Protection Agency
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Table B6 Other normative references (Continued) Reference Title PD5500 1 Specification for Unfired Fusion Welded Pressure Vessels SAE J 517, DIN EN 853, 856, 857 Rubber Hoses and Hose Assemblies SOLAS 1974 with latest amendments 2 (International Convention for the Safety of Life at Sea). 1) Alternative codes and standards that shall be specified at the start of the project. 2) Relevant reference given in the text. Guidance note: The latest revision of the DNV documents may be found in the publication list at the DNV website www.dnv.com. For other sources see DNV-DSS-105 Appendix C.
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B 200 Informative references
Table B7 Informative references Reference Title DNV-OS-D201 Electrical Systems and Equipment DNV-OS-D202 Instrumentation and Telecommunication systems DNV-OS-D301 Fire Protection DNV-RP-A201 Plan Approval Documentation Types - Definitions NORSOK Standard U-100 Manned Underwater Operations EN 849 1 Transportable Gas Cylinders - Cylinder Valves - Specification and Type Testing EN ISO 11114-3 2 Transportable Gas Cylinders - Compatibility of Cylinder and Valve Materials with Gas Contents - Part 3: Autogenous Ignition Test in Oxygen Atmosphere EN ISO 2503 2 Gas Welding Equipment - Pressure Regulators for Gas Cylinders used in Welding, Cutting and Allied Processes up to 300 bar ILO Convention 133 Accommodation of crews 1) Alternative codes and standards that shall be specified at the start of the project. 2) Relevant reference given in the text. B 300 Terminology and definitions 301 The Society signifies Det Norske Veritas AS. 302 The EC signifies the Executive Committee of the Society. 303 Auxiliary Verbal forms are given as follows: 304 “Shall/shall not”: is used to indicate requirements strictly to be followed in order to conform to the document and from which no deviation is permitted. In the cases where text from the IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey is used, the IMO use of “should” shall be interpreted as “shall”. 305 “Should”: shall be used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. 306 “May/need not”: shall be used to indicate a course of action permissible within the limits of the document. 307 “Agreement”, “by agreement”: Unless otherwise indicated, this means agreed in writing between the society, manufacturers, builder and owner. 308 “Administration” means the Government of the State whose flag a ship or floating structure which carries a diving system is entitled to fly or in which the ship or floating structure is registered. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.1) 309 As-built survey: Survey of the installed and completed diving system, which is performed to verify that the completed installation work meets the specified requirements, and to document deviations from the original design, if any. 310 Basket: A divers basket (sometimes known as a stage) is a frame and mesh construction designed to accommodate divers whilst they are lifted in and out of the water. 311 Bell: A diving bell is a frame incorporating a dome, and including appendages, for transfer of divers between the underwater work site and the deck or the surface chamber (TUP or DDC). In the context of this standard, “bell” is defined as an open bell/wet-bell. (See Open Bell, Closed Bell and Wet bell)
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312 “Bottle” means a pressure container for the storage and transport of gases under pressure. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.2) 313 “Breathing gas/breathing mixture” means all gases/mixtures of gases which are used for breathing during diving operations. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.3) 314 Builder: In the context of these rules, signifies the party contracted to build a diving system in compliance with the Society's rules. 315 Built In Breathing System (BIBS): A system of gas delivery to masks, located in the decompression chambers, baskets and wet-bells. This system facilitates breathing in the event of a contaminated atmosphere, and allows for the use of therapeutic gases during decompression. (See Sec.4). BIBS may in rare cases be closed circuit breathing systems (see CCBS definition) but are normally open circuit systems where the exhaled gas is dumped to atmosphere. 316 Case by case: When the case by case approval procedure is used, documentation of the design shall be submitted for approval for each application as required in the applicable chapters of the rules. When the case by case survey procedure is used, the survey shall be performed on the basis of approved design documentation for the actual application and as required in the applicable sections of the rules. Compliance with the approved design documentation and applicable requirements will be documented by certificates as required in the applicable sections of the rules. 317 “Category A machinery spaces” are those spaces and trunks to such spaces as defined in the International Convention for the Safety of Life at Sea, 1974, as amended. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.20) 318 Certificate: A document confirming compliance with the Society's rules or with other rules and regulations for which the Society has been authorized to act. 319 Certification: A service confirming compliance with applicable requirements on the date that the survey was completed. Materials and components in DNV Classified SURFACE diving systems shall be certified according to the level of certification given in DNV-DSS-105. 320 Chamber: Surface decompression, pressure or compression chambers (see also DDC), hereafter called the chambers, and are pressure vessels for human occupancy. 321 Class: In the context of these rules, Class is assigned to and will be retained by the diving system complying with applicable requirements of the Society's rules. 322 Classification: In the context of these rules, a service which comprises the development of independent technical standards for diving systems - and verifies compliance with the rules throughout the vessels' life. 323 Closed bell: A sealed submersible diving chamber (SDC) that locks on and off the chamber where the divers decompress (DDC). Pressure differentials are retained by way of a closed door sealing the divers in at pressures, elevated or lowered compared to the surrounding pressure. Closed bells are not covered by this standard. See DNV-DS-E402. (Note: currently under development, meanwhile use DNV-OS-E402). 324 Closed Circuit Breathing System (CCBS) ‘: A system for supply of breathing gas to the diver and saving of his exhaled gases for re-circulation after scrubbing and replenishing. (see Sec.4) 325 Commissioning: In relation to diving systems, refers to activities which take place after installation and prior to operation, comprising the tests and trials outlined in Sec.2 J. 326 Compact umbilical: Umbilical consisting of composite bundles of hoses, cables and strength members in a braiding or sheathing. (See Sec.4) 327 Compartment: Part(s) of a chamber sufficiently large to contain at least one person and which may have an internal pressure different from adjacent compartments. (see Sec.3) 328 Construction phase: All phases during construction, including fabrication, installation, testing and commissioning, up until the installation or system is safe and operable for intended use. In relation to diving systems, this includes manufacture, assembly, testing, commissioning and repair. 329 Contractor: A party contractually appointed by the Purchaser to fulfil all, or any of, the activities associated with design, construction and operation. 330 Control stations normally as defined in regulation 3 and referred to in regulation 20, chapter II-2 of the International Convention for the Safety of Life at Sea. Control stand or Control station is a control station in which one or more of the following control and indicator functions are centralized: a) Indication and operation of all vital life support conditions, including pressure control b) Visual observation, communication systems including telephones, audio-recording and microphones to public address systems c) Disconnection of all electrical installations and Insulation monitoring d) Provisions for calibration of and comparison between gas analysing
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.1 – Page 14 e) Indication of temperature and humidity in the inner area f) Alarms for abnormal conditions of environmental control systems g) Fixed fire detection and fire alarm systems h) Ventilation fans i) Automatic sprinkler, fire detection and fire alarm systems j) Launch and recovery systems, including interlock safety functions k) Operation and control of the hyperbaric evacuation system 331 Corrosion allowance: Extra wall thickness added during design to compensate for any reduction in wall thickness by corrosion (internally and externally) during operation. 332 Customer: Signifies the party who has requested the Society's service. 333 Deck Decompression Chamber (DDC): Deck mounted Pressure Vessel for Human Occupancy (PVHO) used for decompression. (See Sec.3) 334 “Depth” means the water depth or equivalent pressure to which the diver is exposed at any time during a dive or inside a surface compression chamber or a diving bell. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.6) 335 Design: All related engineering to design the diving system, including both structural as well as material and corrosion. 336 Design life: The initially planned time period from initial installation or use until permanent decommissioning of the equipment or system. The original design life may be extended after a re-qualification. 337 Design load: For PVHOs see Sec.3 B300/400 and for LARS see Sec.7 C100. 338 Design temperature, maximum: The highest possible temperature to which the equipment or system may be exposed to during installation and operation. Environmental as well as operational temperatures shall be considered. Design temperature, minimum: The lowest possible temperature to which the equipment or system may be exposed to during installation and operation, irrespective of the pressure. Environmental as well as operational temperatures shall be considered. Guidance note: For LARS, the design temperature is defined in Standard for Certification 2.22 - Lifting Appliances.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 339 Designer: Signifies a party who creates documentation submitted to the Society for approval or information. 340 Diver heating: A system for actively heating the divers in the water or in the inner area. 341 Divers: Personnel subjected to higher ambient pressure than one atmosphere. 342 “Diving bell” means a submersible compression chamber, including its fitted equipment, for transfer of diving personnel under pressure between the work location and the surface compression chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.7) 343 “Diving system” means the whole plant and equipment necessary for the conduct of diving operations. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.8) Diving system (in DNV terms): The whole plant and equipment necessary for safe conduct of diving operations where compression and decompression of divers are taking place. For classification purposes, SURFACE diving operations are categorized as dmax< 60 msw and Top< 8 hours where msw is metres of sea water 344 dmax: Maximum operating depth of the SURFACE diving system. This is the depth corresponding to the maximum pressure for pressurizing divers. (For Classified systems this may be specified in the certificate and Data Sheet). 345 DSV: Class Notation in DNV representing ‘Diving Support Vessel'. 346 ECU: Environmental Control Unit. Maintains Temperature, reduces humidity and may include removal of carbon dioxide. (see Sec.4) 347 Enriched air: Nitrogen oxygen mixtures with elevated oxygen content. (See NITROX) 348 Equipment lock: A pressure tight independent lock mounted on the shell of the chamber providing the means for locking in equipment necessary for the divers and the operation of the system. (See also Medical lock) 349 “Evacuation system” means a system whereby divers under pressure can be safely evacuated from a ship or floating structure to a position where decompression can be carried out. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.9) 350 Fabrication: Activities related to the assembly of objects with a defined purpose. In relation to diving systems, fabrication refers to e.g. deck decompression chambers, wet-bells, and pressure vessels for gas storage, environmental control systems, launch and recovery systems etc.
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351 Fabricator: The party performing the fabrication (in this context, normally of windows for PVHOs). 352 Failure: An event affecting a component or system and causing one or both of the following effects: — loss of component or system function — deterioration of functional capability to such an extent that the safety of the installation, personnel or environment is significantly reduced 353 Fatigue: Cyclic loading causing degradation of the material. 354 Flag administration: The maritime administration of a vessel's country of registry. 355 Gas: In the context of this standard, gas includes air, oxygen and Enriched air/NITROX. 356 Gas containers: Cylinders, bottles and pressure vessels for storage of pressurized gas. (see Sec.3 and 4) 357 Guidance notes: Contain advice which is not mandatory for the assignment or retention of class, but with which the Society, in light of general experience, advises compliance. 358 “Handling system” means the plant and equipment necessary for raising, lowering and transporting the diving bell between the work location and the surface compression chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.10) (See Launch and recovery System-LARS) 359 “Hazardous areas” are those locations in which an explosive gas-air mixture is continuously present, or present for long periods (zone O); in which an explosive gas-air mixture is likely to occur in normal operation (zone 1); in which an explosive gas-air mixture it not likely to occur, and if it does it will only exist for a short time (zone 2). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.11) 360 HAZOP (HAZard and OPerability study): The application of a formal systematic critical examination to the process and engineering intentions of new or existing facilities to assess the hazard potential of inadvertent operation or malfunction of individual items of equipment and their consequential effects on the facility as a whole (Chemical Industries Association HAZOP Guide). 361 Hydro-test or Hydrostatic test: See Pressure test 362 Hyperbaric Evacuation System (HES): System for evacuating divers under pressure. This includes the Hyperbaric Evacuation Unit (HEU), the launch and recovery and control systems. (See Sec.9) 363 Hyperbaric Rescue Vessel (HRV): IMO uses the term Hyperbaric Evacuation Unit (HEU). See above. 364 IACS: The International Association of Classification Societies. 365 IMO: Signifies the International Maritime Organization. 366 Inner area: The areas which are inside the chambers. Interconnecting trunks are considered part of the inner area when the door is opened into the chamber. 367 Inspection: Activities such as measuring, examination, testing, gauging one or more characteristics of a product or service and comparing the results with specified requirements for determine conformity. 368 Installation (activity): The operations related to installing the equipment, diving system or support structure, e.g. mounting chambers, gas cylinders, ECUs, panels, interconnecting piping, launch and recovery systems etc., including final testing and preparation for operation. 369 Installation Manual (IM): A document prepared by the Contractor to describe and demonstrate that the installation method and equipment used by the Contractor will meet the specified requirements and that the results can be verified. 370 ISO: Signifies the International Organisation for Standardization. 371 Launch and recovery system (LARS): The system and equipment necessary to launch and recover the divers, the diver’s basket or wet-bell to the chambers as well as transport the divers between the surface support unit and the underwater working site, including any guide rope systems and cursor systems. (See Sec.7) 372 Lay-up: A terminology used for diving systems that are out of commission. In this state the diving system may be installed on board or permanently stored on shore. 373 “Life support system” means the gas supply, breathing gas system, decompression equipment, environmental control system and equipment required to provide a safe environment for the diving crew in the diving bell and the surface compression chamber under all ranges of pressure and conditions they may be exposed to during diving operations. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.12) Life support systems (in DNV terms): The systems comprising gas supply systems, breathing gas systems, pressure regulating systems, environmental control systems, and systems required to provide a safe habitat for the divers, in the basket, the wet-bell and the chamber compartments under normal conditions during SURFACE diving operation. (See Sec.4) 374 “Living compartment” means the part of the surface compression chamber which is intended to be used
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.1 – Page 16 as the main habitation for the divers during diving operations and which is equipped for such purpose. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.13) Living compartment (in DNV terms): A compartment which is intended to be used as the main habitation for the divers and which is equipped as such. 375 Load: Any action causing stress, strain, deformation, displacement, motion, etc. to the equipment or system. 376 Load effect: Effect of a single load or combination of loads on the equipment or system, such as stress, strain, deformation, displacement, motion, etc. 377 Load effect factor: The partial safety factor by which the characteristic load effect is multiplied to obtain the design load effect. 378 Lot: A number of components from the same batch. E.g. same heat, the same heat treatment batch and with the same dimensions. 379 “Main components” of a diving system include the surface compression chamber, diving bell, handling system and fixed gas storage facilities. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.14) 380 Manufacture: Making of articles or materials, often in large volumes. In relation to diving systems, refers to activities for the production of pressure vessels, panel, and life support systems etc., performed under contracts from one or more Contractors. 381 Manufacturer: Signifies the entity that manufactures the material or product, or carries out part production that determines the quality of the material or product, or does the final assembly of the product. 382 “Mating device” means the equipment necessary for the connection and a disconnection of a diving bell to a surface compression chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.15) 383 “Maximum operating depth” of the diving system is the depth in metres or feet of seawater equivalent to the maximum pressure for which the diving system is designed to operate. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.16) 384 Medical lock: A pressure tight independent lock mounted on the shell of the chamber providing the means for locking in provisions, medicine and equipment necessary for the divers and the operation of the system. (See also Equipment lock) 385 NDE level: The extent and acceptance criteria for the NDE of the components. 386 NITROX: Nitrogen oxygen mixtures with elevated oxygen content. (See Enriched air) 387 Nominal outside diameter: The specified outside diameter. This shall mean the actual outside diameter. 388 Nominal wall thickness: The specified non-corroded wall thickness, which is equal to the minimum steel wall thickness plus the manufacturing tolerance. 389 Normal cubic meters: (Nm3) is taken as cubic meters of gas at standard conditions of 0°C and 1.013 bar. 390 Open bell (also known as Wet bell): A suspended canopy chamber, open at the bottom like a moon pool structure that is lowered underwater to operate as a stage for the divers with the advantage of providing an air pocket for refuge and a space for communication outside the mask/helmet. 391 Operation, Incidental: Conditions that are not part of normal operation of the equipment or system. In relation to diving systems, incidental conditions may lead to incidental pressures. 392 Operation, Normal: Conditions that arise from the intended use and application of equipment or system, including associated condition and integrity monitoring, maintenance, repairs etc. In relation to diving systems, this should include, start and finish of dives (pre- and post-dive checks), treatment of decompression-related incidents, gas transfer and changing out of consumables. 393 “Organization” means the International Maritime Organization (IMO). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.17) 394 Out of roundness: The deviation of the perimeter from a circle. This can be stated as ovalisation (%), or as local out of roundness, e.g. flattening, (mm). 395 Outer area: Those areas of the diving system that are exposed to atmospheric conditions during operation, i.e. outside the inner system and the room or area that surrounds or contains the diving system. 396 Ovalisation: The deviation of the perimeter from a circle. This has the form of an elliptic cross section. 397 Owner: Signifies the registered owner or manager of the diving system or any other organization or person who has assumed the responsibility for operation of the diving system and who on assuming such responsibility has agreed to take over all the duties and responsibilities. 398 Oxygen systems: Systems intended for a gas with a higher oxygen percentage than 25%. 399 Personal diving equipment: Equipment carried by the diver on his person including his tools, diving suit, diving helmet and self-contained breathing apparatus with gas bottles. This is normally not included in the SURFACE diving system specified in this standard.
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B 400 Terminology and definitions (continued) 401 Plan approval: Signifies a systematic and independent examination of drawings, design documents or records in order to verify compliance with the rules or statutory requirements. Plan approval will be carried out at the discretion of the Society, which also decides the extent and method of examination. 402 Planned Maintenance System (PMS): A system for planning and recording of maintenance activities. 403 Pressure control system: In relation to diving systems, this is the system for control of the pressure in the various systems, comprising the pressure regulating system, pressure safety system and associated instrument and alarm systems. 404 Pressure regulating system: In relation to diving systems, this is the system which ensures that, irrespective of the upstream pressure, a set pressure is maintained downstream (at a given reference point) for the component. 405 Pressure safety system: The system which, independent of the pressure regulating system, ensures that the allowable set pressure is not exceeded. 406 Pressure test: The hydrostatic pressure test initially performed at the manufacturer of the pressure vessel in accordance with requirements in the design code. 407 Pressure, Collapse: Characteristic resistance against external over-pressure. 408 Pressure, Design: In relation to diving system assemblies, this is the maximum internal pressure during normal operation, referred to a specified reference point, to which the component or system section shall be designed. The design pressure must take account of the various pressurised components in the adjoining systems, and their relative design pressures. 409 Pressure, System test: In relation to diving systems, this is the internal pressure applied to the component or system during testing on completion of installation work to test the diving system for tightness (normally performed as hydrostatic testing). 410 “Pressure vessel” means a container capable of withstanding an internal maximum working pressure greater than or equal to 1 bar. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1 3.18) 411 Purchaser: The owner or another party acting on his behalf, who is responsible for procuring materials, components or services intended for the design, construction, installation or modification of a SURFACE diving system. 412 Quality Assurance (QA): Planned and systematic actions necessary to provide adequate confidence that a product or service will satisfy given requirements for quality. 413 Quality Plan (QP): The document setting out the specific quality practices, resources and sequence of activities relevant to a particular product, project or contract. A quality plan usually makes reference to the part of the quality manual applicable to the specific case. 414 Quality system: Signifies both the quality management system and established production and control procedures. 415 Reliability: The probability that a component or system will perform its required function without failure, under stated conditions of operation and maintenance and during a specified time interval. 416 Re-qualification: The re-assessment of a design due to modified design premises and or sustained damage. 417 Resistance: The capability of a structure, or part of a structure, to resist load effects. 418 Risk: The qualitative or quantitative likelihood of an accidental or unplanned event occurring, considered in conjunction with the potential consequences of such a failure. In quantitative terms, risk is the quantified probability of a defined failure mode times its quantified consequence. 419 Rules: All requirements adopted by the EC as the basis for classification. 420 Saturation diving: Once a diver becomes saturated with the gases that make decompression necessary, the diver does not need additional decompression. When the blood and tissues have absorbed all the gas they can hold at that depth, the time required for decompression becomes constant. As long as the depth is not increased, additional time on the bottom is free of any additional decompression. Saturation diving equipment is not covered in this standard. Reference is given to DNV-DS-E402. (Note: currently under development, meanwhile use DNV-OS-E402). 421 Self Propelled Hyperbaric Lifeboat (SPHL): (see HEU and DNV-DS-E402 (Note: currently under development, meanwhile use DNV-OS-E402).) 422 Significant wave height: When selecting the third of the number of waves with the highest wave height, the significant wave height is calculated as the mean of the selection. 423 Specified Minimum Tensile Strength: The minimum tensile strength prescribed by the specification or standard under which the material is purchased. 424 Specified Minimum Yield Stress: The minimum yield stress prescribed by the specification or standard under which the material is purchased.
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425 Submersible Decompression Chamber (SDC): Closed bell. (Not applicable to this standard. See DNV- DS-E402. Note: under development, meanwhile use DNV-OS-E402). 426 Suitable breathing gas: A gas or gas mixture that is breathable to divers for the pressure and duration they are exposed to it. In the context of this standard, suitable breathing gases include air, oxygen and Enriched air/NITROX. NB. Pure Oxygen is NOT considered suitable for breathing in water. 427 Supplementary requirements: Requirements for material properties of component that are additional to the basic requirements, and that are intended to apply to components used for specific applications. 428 “Surface compression chamber” means a pressure vessel for human occupancy with means of controlling the pressure inside the chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.5) 429 Survey: Signifies a systematic and independent examination of a diving system, materials, components or systems in order to verify compliance with the rules and/or statutory requirements. Surveys will be carried out on the vessel, at the construction or repair site as well as at sub-suppliers and other locations at the discretion of the Society, which also decides the extent and method of control. 430 Tentative rules: Provisional requirements and/or guidelines to which the Society reserves the right to make adjustments in order to obtain the intention reflected in the rules.
431 Top: Maximum operation time, i.e. the time from start of pressurization of the diver, until the diver is back to atmospheric conditions. 432 Transfer compartment: Compartment that is intended to be used for a lock-in or -out operation of divers between other compartments or outer area. Also known as TUP (Transfer Under Pressure) The diving system should be capable of allowing the safe transfer of a person under pressure from the diving bell to the surface compression chamber (and vice versa). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.2.7) 433 Transferable diving system: A diving system designed to be easily transferable in one or more units and which may be installed on-board a ship, barge or offshore platform for a short period of time not exceeding one year. A transferable diving system may be assembled from different units into a particular configuration suitable for a specific working operation. 434 Trunk: In the context of pressure vessels for human occupancy, trunk denotes the cylindrical spool-piece connecting separate chambers. The maximum length of these cylindrical trunks is considered to be 1400 mm. In the context of separation of fire resistant enclosures to Category A machinery spaces, a trunk is a small enclosed room defined in SOLAS Ch.II-2 Reg.9.2 Thermal and structural boundaries. 435 Type approval: is a procedure for plan approval. Type approval can be applied to products, groups of products, systems or retention survey. This procedure should normally be used for approval of standard designs. The type approval procedure may consist of the following elements: plan approval, initial survey, type testing and issue of a type approval certificate. The type approval procedure used by DNV is described in DNV Standard for Certification No. 1.2. 436 Ultimate Tensile Strength (UTS): The measured ultimate tensile strength. 437 “Umbilical” means the link between the diving support unit and the diving bell and may contain surveillance, communication and power supply cables, breathing gas and hot water hoses. The hoisting and lowering strength member may be part of the umbilical. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 1.3.19) Umbilical (in DNV terms): A link between support vessel and the divers, or the diving wet-bell, which may contain gas hoses, hot water hose, power supply cables and communication cables. (See Sec.4) 438 Verification: A service that signifies a confirmation through the provision of objective evidence (analysis, observation, measurement, test, records or other evidence) that specified requirements has been met. 439 Wet bell = Open bell 440 Witnessing: Signifies attending tests or measurements where the surveyors verify compliance with agreed test or measurement procedures. 441 Work: All activities to be performed within relevant contract(s) issued by Owner, Builder or Manufacturer. 442 Working weight: of the basket or wet-bell shall be taken as the maximum weight of the fully equipped basket or wet-bell, including each fully equipped diver of 200 kg. The load from this weight applies to: a) launch and recovery in air, and b) launch and recovery submerged, combining the maximum negative buoyancy of the wire rope, umbilical and basket or wet-bell at maximum operating depth 443 Yield Stress: The measured yield tensile stress.
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B 500 Abbreviations and symbols (guidance)
API American Petroleum Institute ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials AUT Automatic Ultrasonic Testing BIBS Built In Breathing System BS* British Standard (Note: Now PD – Public document) CCBS Closed Circuit Breathing System CE Conformité Européenne (European Conformity) C-Mn Carbon Manganese CRA Corrosion Resistant Alloy DDC Deck Decompression Chamber DNV Det Norske Veritas DP Dynamic Positioning DSV Diving Support Vessel ECU Environmental Control Unit EBW Electronic Beam Welded FMEA Failure Mode Effect Analysis HAZ Heat Affected Zone HAZOP Hazard and Operability Study HES Hyperbaric Evacuation System HEU Hyperbaric Evacuation Unit HFW High Frequency Welding HPIC Hydrogen Pressure Induced Cracking HRC Hyperbaric Rescue Chamber HRV Hyperbaric Rescue Vessel IM Installation Manual IMO International Maritime Organisation ISO International Organisation for Standardisation KV Charpy value LARS Launch and Recovery System LBW Laser Beam Welded MPQT Manufacturing Procedure Qualification Test MPS Manufacturing Procedure Specification MSA Manufacturing Survey Arrangement NACE National Association of Corrosion Engineers NDE Non-Destructive Examination NDT (Non-Destructive Testing) see NDE NPD Norwegian Petroleum Directorate (now PSA) P Production PMS Planned Maintenance System PSA Petroleum Safety Authority Q Qualification QA Quality Assurance QC Quality Control QP Quality Plan QRA Quantitative Risk Analysis ROV Remotely Operated Vehicle SDC Submersible Decompression Chamber TUP Transfer Under Pressure UTS Ultimate Tensile Strength WPS Welding Procedure Specification YS Yield Stress
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501 Symbols
A = Cross section area D = Nominal outside diameter Dmax = Greatest measured inside or outside diameter Dmin = Smallest measured inside or outside diameter Di = D - 2 tnom = Nominal internal diameter E = Young’s Modulus
f0 =
H = Wave height Hs = Significant wave height ID = Nominal inside diameter O = Out of roundness, Dmax - Dmin OD = Nominal outside diameter T = Operating temperature Tmax = Maximum design temperature T min = Minimum design temperature T nom = Nominal thickness
C. Procedural Requirements C 100 Certification and approval requirements 101 For Classification of SURFACE diving systems by DNV the certification of materials, components and systems will be documented with certification requirements given in DNV-DSS-105. 102 In accordance with the DNV Rules for Classification of Ships Pt.1 Ch.1 Sec.4 B, the following types of documents apply: a) Det Norske Veritas Certificate (NV): A document validated and signed by a surveyor of the Society stating: i) conformity with rule requirements ii) that tests are carried out on the certified product itself and/or iii) that tests are made on samples taken from the certified product itself iv) that tests are performed in presence of the surveyor or in accordance with special agreements b) Works Certificate (W): A document signed by the manufacturer stating: i) conformity with rule requirements ii) that tests are carried out on the certified product itself and/or iii) that tests are made on samples taken from the certified product itself iv) that tests are witnessed and signed by a qualified department of the manufacturers c) Test Report (TR): A document signed by the manufacturer stating: i) conformity with rule requirements ii) that tests are carried out on samples from the current production 103 The applicable chapters and sections of the rules specify which of the above mentioned documents are required. 104 Where the rules require works certificate or test report, the surveyor may at any time require the tests to be carried out in his presence and/or that the surveyor check elements of the production control.
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SECTION 2 DESIGN PHILOSOPHY AND PREMISES – SURFACE DIVING SYSTEMS
A. Introduction A 100 Objectives 101 The objectives of this section are to present the safety philosophy applied in this standard, to identify and provide a basis for definition of relevant system design characteristics. These are, key issues required for design, construction, operation and re-qualification of SURFACE diving systems. 102 This section also refers to minimum requirements for documentation for design, manufacture, installation and some operational aspects. A 200 Scope 201 The scope of this section is to outline the requirements for planning and documenting system philosophy, safety philosophy and the management of quality. A 300 Application 301 This section applies to all SURFACE diving systems, which shall be built in accordance with this standard. 302 This section bears impact upon all other sections in this standard. A 400 References 401 Reference to normative rules, codes and standards are given under A400 in each relevant section. A 500 Procedural requirements, approval & certification 501 Approval and Certification requirements are given in DNV-DSS-105 Appendix A. A 600 Documentation 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. 602 Specific document requirement lists are given in A600 under each section. 603 For general requirements, see B. A 700 Survey and testing requirements during and after manufacturing and assembly 701 The tests to be carried out are stated in A700 under each relevant section in this standard and in DNV- RP-E401. Additional tests may, however, be required. 702 When a diving system is built according to this standard, an inspector or surveyor shall verify that: a) the design and scantlings comply with the approved plans and the requirements in this standard and other specified recognized standards, codes, and national regulations b) that the materials and components are certified according to this standard and the terms of delivery c) that the work is carried out in accordance with the specified fabrication tolerances and required quality of welds etc. d) that all required tests are carried out 703 The inspection shall be carried out at the manufacturers and/or builder, during or after the manufacture/ assembly. The extent and method of examination shall be agreed in the terms of delivery and the specifications. 704 Testing shall be in compliance with approved programmes. A 800 Survey and testing requirements during and after installation 801 The tests to be carried out are stated in A800 under each relevant section in this standard and in DNV- RP-E401. Additional tests may, however, be required. 802 The diving system shall be tested at sea trials on-board according to an approved programme. 803 During the sea trials the normal launch and recovery system will be tested to the maximum depth. For SURFACE diving systems employing a “wet-bell” the bell shall be checked for leakage at depth, including gas cylinders, piping and hoses. 804 Drills should be held to assure adequate access for the divers, and the ability to transfer an injured diver, to the chamber, and to compress the chamber, within the time frame stipulated by the applied decompression tables.
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A 900 Marking and signboards 901 Marking and signboard requirements are given under A900 in each relevant section. 902 Labels (nameplates) of flame retardant material bearing clear and indelible markings shall be placed so that all equipment necessary for operation (valves, detachable connections, switches, warning lights etc.) can be easily identified. The labels are to be permanently fixed. A 1000 Materials 1001 Material specifications and requirements are given under A1000 in each relevant section.
B. Documentation B 100 General 101 For installation of diving systems on board, or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. 102 This section specifies the general requirements for documentation during diving system design, manufacturing, fabrication, installation, commissioning and operation.Specific document requirement lists are given in A600 under each section. General requirements are given in DNV Rules for Classification of Ships Pt.0 Ch.3 Sec.1. 103 In accordance with quality system requirements, such as those outlined in ISO 9001:2008-4.4 (especially 4.4.5) and 4.5 (especially 4.5.2), design output shall be documented and expressed in terms that can be verified and validated against design input requirements. The supplier shall establish and maintain documented procedures to control all documents and data. 104 All documentation requirements shall be reflected in a document register. The documentation shall cover design, manufacturing, fabrication, installation and commissioning. As a minimum, the register shall reflect activities from the start of design to operation of the diving system. 105 The documentation shall be submitted to the relevant parties for acceptance, verification or information as agreed in ample time before start of fabrication. Documentation pertaining to the system philosophy, concept and manufacturing procedure specification, shall be submitted for approval and information at the start of the project to enable systematic review. 106 Verified documentation shall be available at the work site before manufacturing commences. B 200 Documentation of arrangement 201 List and information stating the following particulars for the diving system shall be included in the Manufacturing Procedure Specification that shall be submitted at the start of the project: a) Maximum operating depth dmax b) Maximum operation time Top c) Maximum number of divers in the basket(s) or wet-bell(s) d) Maximum number of divers in the chamber(s) e) Maximum operational sea-state f) Extract from the operation manual, stating the operational procedures, which are to be the basis for the design. Plans showing general arrangement of the diving system, location and supporting arrangement g) Plans showing the lay-out of control stand(s) h) Proposed program for tests and trials of systems for normal operation and for emergency use B 300 Documentation of installation 301 Detailed plans, drawings and procedures shall be prepared for all installation activities. The following shall as a minimum be covered: a) diving system location overview (planned or existing) b) other vessel (or fixed location) functions and operations c) list of diving system installation activities d) alignment rectification e) installation of supporting structure f) installation of interconnecting services g) installation of protective devices h) hook-up to support systems
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.2 – Page 23 i) as-built survey j) final testing and preparation for operation B 400 Documentation for systems in operation 401 Plans for diving system operation, inspection, maintenance and repair shall be prepared in a Survey Planning Document prior to start of operation. (See DNV-RP-E401) All operational aspects shall be considered when selecting the diving system concept. 402 The diving system operational planning shall as a minimum cover: a) organisation and management b) start-up and shut-down (pre- and post-dive) c) operational limitations d) emergency operations e) maintenance f) corrosion control, inspection and monitoring g) general inspection h) special activities 403 In order to carry out periodical surveys, the minimum documentation shall include: a) personnel responsible for the operation of diving system b) history of diving system operation with reference to events which may have significance to design and safety c) a log of the total number of dives and hours of operation in the periods between annual surveys d) records of new equipment installed and old equipment removed e) the originally approved viewports for the system shall be included in the operational documentation f) installation condition data as necessary for understanding diving system design and configuration, e.g. previous survey reports, as-built installation drawings and test reports g) inspection, testing and maintenance schedules and their records 404 In case of mechanical damage or other abnormalities that might impair the safety, reliability, strength and stability of the diving system, the following documentation shall, as a minimum, be prepared prior to start- up of the diving system: a) description of the damage to the diving system, its sub-systems or components with due reference to location, type, extent of damage and temporary measures, if any b) plans and full particulars of repairs, modifications and replacements, including contingency measures c) further documentation with respect to particular repair, modification and replacement, as agreed upon in line with those for the manufacturing or installation phase B 500 Documentation for systems in demobilisation 501 Demobilisation shall be planned and prepared and the evaluation shall include the following aspects: a) safety aspects, during and after demobilisation b) environmental aspects, e.g. pollution c) impact on other structures d) possible reuse of equipment at a later stage (re-qualification and certification) Guidance note: For diving systems that are transferred between vessels, the advantage of retaining Class in lay-up is found in the ease of mobilising on a new location.
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B 600 Filing of documentation 601 Maintenance of complete files of all relevant documentation during the life of the diving system is the responsibility of the owner. 602 The engineering documentation shall be filed by the owner or by the engineering contractor for the lifetime of the system. 603 Design basis and key data for the diving system shall be filed for the lifetime of the system. This includes
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.2 – Page 24 documentation from design to start-up and also documentation from possible major repair or modification of the diving system. 604 Files to be kept from the operational and maintenance phases of the diving system shall, as a minimum, include final in-service inspection reports from start-up, periodical and special inspections, condition monitoring records, and final reports of maintenance and repair.
C. Safety Philosophy C 100 General 101 The integrity of a SURFACE diving system constructed to this standard shall be ensured through a safety philosophy integrating the different parts. The objective of this standard is that the design, materials, fabrication, installation, commissioning, operation, repair, and re-qualification, of diving systems are safe and conducted with due regard to public safety and the protection of the environment. C 200 Safety objective 201 The purchaser/owner shall define an overall safety objective; planned, established and implemented, covering all phases from conceptual development until demobilisation and scrapping. The safety objective shall address the main safety goals as well as establishing acceptance criteria for the level of risk acceptable to the owner. C 300 Systematic review 301 All work associated with the design, construction and operation of the diving system shall be such that it ensures that the requirements in the safety philosophy are met. As a minimum, it shall ensure that no single failure shall lead to life-threatening situations for any person or to unacceptable damage to the facilities or the environment. 302 A systematic review or analysis shall be carried out at all phases in order to identify and evaluate the consequences of single failures and series of failures in the diving system, such that necessary remedial measures can be taken. The extent of the review or analysis shall reflect the criticality of the diving system, the criticality of a planned operation and previous experience with similar systems or operations. This review shall identify the risk to the operation of the diving system and to the health and safety of personnel associated with it or in its vicinity. The scope of the review should be agreed upon. 303 Once the risks have been identified their extent can be reduced to a level as low as reasonably practicable by means of one or both of: a) reduction in the probability of failure b) mitigation of the consequences of failure The result of the systematic review of these risks is measured against the safety objectives. 304 Special attention shall be given to the risk of fire and launch and recovery operations. C 400 Quality management systems 401 Adequate quality management systems shall be implemented according to requirements in DNV Rules for Classification of Ships Pt.2 Ch.3 Sec.2B to ensure that gross errors in the work for diving system design, construction and operations are limited. C 500 Inspection and test plans 501 The tabular description of the inspections and tests to be carried out during the work is frequently known as the inspection and test plan (ITP).The following items shall be checked for inclusion within the Inspection and Test Plan: a) each inspection and test point and its relative location in the production cycle shall be shown b) the characteristics to be inspected and tested at each point shall be identified c) the use of sub-contractors shall be indicated and details of how the verification of sub-contractor’s quality shall be carried out shall be shown d) hold points established by the constructor, the operator or a third party, where witness or review of the selected inspection or test is required, shall be shown
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D. SURFACE Diving System Philosophy D 100 General 101 As far as reasonable and practicable, a diving system should be designed to minimize human error and constructed so that the failure of any single component (determined, if necessary, by an appropriate risk assessment) should not lead to a dangerous situation. (IMO Code of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.1.1) Guidance note: Whereas this is a general requirement for the systems, it is recognised that certain components cannot fulfil this requirement in and of themselves. A typical example of this is the Pressure Vessel for Human Occupancy with acrylic windows and the umbilicals. In these cases the applicable standards will specify stringent safety factors. For other cases a formal safety assessment may be required.
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D 200 System integrity 201 All components in a diving system should be designed, constructed and tested in accordance with international or national standards * recognized by the Administration or proprietary specifications acceptable to the Administration. * Such as those of a recognized classification society which has rules for diving systems acceptable to the Administration. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.4) 202 SURFACE diving systems shall be designed, constructed and operated in such a manner that they: a) fulfil the specified operational requirements b) fulfil the defined safety objective and have the required support capabilities during planned operational conditions c) have sufficient safety margin against accidental loads or unplanned operational conditions d) consider the possibility of changes in the operating conditions and criteria during the lifetime of the system 203 Any re-qualification deemed necessary due to changes in the design conditions shall take place in accordance with provisions set out in each section of the standard. D 300 Essential services 301 Essential services are herein defined as those services that need to be in continuous operation for maintaining the diving system's functionality with regard to sustaining the safety, health and environment of the divers in a hyperbaric environment. This includes services required by the crew monitoring the divers. 302 Essential services shall be maintained for the period required by safely terminating the SURFACE diving operation, including time for decompression of the divers. 303 For services supporting divers in the water, all services are essential. 20 minutes is considered to be the minimum time required ensuring that the divers are safely recovered to the wet-bell, or to the surface. 304 For services supporting divers in a wet-bell, all services are essential. 20 minutes is considered to be the minimum time required ensuring that the divers are safely recovered into the decompression chambers or to the surface. 305 For services supporting divers in the decompression chambers, all required services are essential. The specified maximum decompression schedule is considered to be the minimum time required ensuring that the divers are safely brought to the surface. D 400 Emergency services 401 Emergency services are herein defined as those services that are essential for safety in an emergency condition. Examples of equipment and systems for emergency services include: a) emergency lighting, including external strobe lighting on basket/wet-bell b) emergency communication c) emergency life support systems involving pressure containment, oxygen supplies and CO2 scrubbing d) emergency heating/cooling systems e) condition monitoring of emergency batteries f) alarm systems for the above emergency services g) emergency launch and recovery of the wet-bell(s)/basket(s)/diver(s) (if electrical)
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402 For services supporting divers in the water, all the above services may be considered emergency services and 20 minutes is considered to be the minimum time required to ensure that the divers are safely recovered in the wet-bell or basket or to the surface. 403 For services supporting divers in a wet-bell, all the above services may be considered emergency services and 20 minutes is considered to be the minimum time required to ensure that the divers are safely recovered in the decompression chambers or to the surface. 404 For services supporting divers in the decompression chambers, all the above services may be considered emergency services with the exception of launch and recovery systems. 405 Services supporting hyperbaric evacuation system are considered statutory scope and therefore reviewed on a case by case basis according to instructions from the applicable Administration. D 500 Non-important services 501 Non-important services are those which are not essential/emergency according to the above. D 600 Layout and arrangement of the SURFACE diving system 601 All components in a diving system should be so designed, constructed and arranged as to permit easy cleaning, disinfection, inspection and maintenance. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.6) 602 The layout of the diving system shall ensure protection from accidental damage and accessibility for safe operation, maintenance and inspection. The diving system shall be so designed that the divers and assisting personnel are provided with safe and comfortable operating conditions. Ergonomic principles shall be applied in the design of working systems. (i.e. in accordance with DNV-OS-D202 Ch.2 Sec.5 and ISO 6385.) 603 The elements of the SURFACE diving system shall be configured in such a way as to ensure that a clear access route is available from the LARS to the decompression chamber, with a distance as short as practicable and not more than that which provides enough time according to the maximum allowable surface interval stipulated in the applied decompression tables. D 700 Wet-bell – if installed 701 Wet-bells are not mandatory for the classification of SURFACE diving systems. However, if wet-bells are employed, they shall meet the requirements for bells given in his standard. 702 A diving bell should provide a suitable environment and facilities for the persons who use it, having regard to the type and duration of the diving operation. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.3.3) 703 Diving bells should be so designed as to provide adequate space for the number of occupants envisaged, together with the equipment. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.3.5)
E. External and Internal Environmental Conditions E 100 General 101 Diving systems and components thereof should be designed for the conditions under which they are certificated to operate. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.2) 102 Systems and components shall be designed for the environmental conditions given in the diving system specifications. Bells and baskets shall meet the environmental requirements for surface and submerged components. The specifications shall state the limitations on roll, maximum current etc. in order to avoid the basket/bell impacting the ships side or getting trapped under bilge keel. 103 Environmental phenomena that might impair proper functioning of the system or cause a reduction of the reliability and safety of the system shall be considered in the MPS (including fixed and land-based installations) as follows: a) Wind and Tide b) Waves and Currents c) Air and sea temperatures and Ice E 200 External operational conditions 201 Materials for diving system components should be suitable for their intended use. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.3)
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202 Design inclinations shall be assumed according to Table E1 unless otherwise specified in the system specifications.
Table E1 Design inclinations Location Roll Permanent list Pitch Trim
Chambers and other surface installations: On a ship +/-22.5° +/-15° +/-10° +/-5°
On a mobile offshore unit +/-15° +/-15°
Components in a basket or wet-bell +/-45° +/-22.5°
Guidance note: For launch and recovery systems the operational design sea-state is given in Sec.7.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 203 Range of ambient temperature: -10°C to 55°C, unless otherwise specified. For greater temperature ranges, temperature protection shall be provided. 204 Humidity: 100%. 205 Atmosphere contaminated by salt (NaCl): Up to 1 mg salt per 1 m3 of air, at all relevant temperatures and humidity conditions. E 300 Internal operational conditions (Inner area) 301 Range of ambient pressure is given by the design code or as a minimum range of 1 bar to 1.3 times the pressure corresponding to dmax with pressurisation and depressurisation rates as specified in Sec.4 C100, whichever is the greater range. This shall be applicable to materials and components installed in the Pressure Vessels for Human Occupancy. 302 Range of ambient temperature: 5°C to 55°C, unless otherwise specified. Guidance note: Ambient pressure and temperature is here understood to be the pressure and temperature of the environment surrounding the equipment or components utilised in the diving system.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 303 Relative humidity: Up to 100%. 304 Atmosphere contaminated by salt (NaCl): Up to 1 mg salt per 1 m3 of air, at relevant temperatures and humidity conditions. 305 There shall be a limitation on maximum oxygen atmosphere content of 23.5% in manned diving chambers to ensure that the effects from fire-extinguishing systems / extinguishers have the intended effect. 306 A description of the internal conditions during storage, construction, installation, pressure testing and commissioning shall be prepared. The duration of exposure to seawater or humid air, and the need for using measures to control corrosion shall be considered. When choosing materials, paints etc. the potential for emission of hazardous compounds shall be considered. 307 Statutory requirements apply for determination of exposure limits such as: a) American Conference of Governmental Industrial Hygienists, Documentation of the Threshold Limit Values and Biological Exposure b) European Commission Directive on Occupational Exposure Limit Values c) Health and Safety Executive Occupational Exposure Limits d) NASA. Spacecraft maximum allowable concentrations for airborne contaminants (SMAC), 1999. e) ACGIH. TLVs and BEIs. Ohio: American Conference of Governmental Industrial Hygienists. f) Segadal K, Djurhuus R, Roseth I. Implementation of a standard procedure for routine surveillance of chemical contamination of diving atmosphere during diving operations in 1995. Bergen: Norwegian Underwater Technology Centre AS, 1995; NUTEC report no. 27-95. g) Djurhuus R, Jakobsen K, Sundland H, Lindrup AG, Solheim E. Procedure for testing for off gassing from materials used in diving systems. (In Norwegian). Bergen: Norwegian Underwater Technology Centre AS, 1994; NUTEC report no. 5-94. h) Ahlen C. Cleaning and Disinfection of Operational Saturation Diving Systems. Recommendations for an Industrial Standard. (In Norwegian). Trondheim: SINTEF, 1999; STF78 A99123.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.2 – Page 28 i) Ahlen C, Zahlsen K. FUDT-Bacteriology 1991. Disinfecting in hyperbaric environments. (In Norwegian). Trondheim: SINTEF, 1992; STF23 F92015. Note that the exposure limits need to be translated into a form relative to the depth exposure and atmosphere. 308 In order to assess the need for internal corrosion control, including corrosion allowance and provision for inspection and monitoring, the following conditions shall be considered: a) maximum and average operating temperature and pressure profiles of the components, and expected variations during the design life b) expected content of dissolved salts in fluids, residual oxygen and active chlorine in sea water c) chemical additions and provisions for periodic cleaning d) provision for inspection of corrosion damage and expected capabilities of inspection tools (i.e. detection limits and sizing capabilities for relevant forms of corrosion damage) e) the possibility of wear and tear, galvanic effects and effects in still water pools shall be considered E 400 Submerged components 401 Range of ambient temperature: -2°C to 30°C. Guidance note: Ambient temperature may in this case fall outside the range stipulated. This shall be agreed on a case-by-case basis and stated in the certificates.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 402 Range of ambient pressure: 1 bar to 1.3 times the pressure corresponding to maximum operating depth. Environmental requirements apply to submerged materials and components. 403 Salinity of ambient water: 35 parts per thousand. 404 The pressure equivalent to depth of seawater at 0°C with 3.5% salinity may be taken as 1.006 bar per 10 msw (meter seawater), as a mean value. For saltwater, the density may be taken to vary as follows: — 0.05% increase for each 100 m of depth increase — 0.4% increase for an increase in salinity from 3.5% to 4.0% — 0.3% decrease for an increase in temperature from 10°C to 20°C 405 For the selection and detailed design for external corrosion control, the conditions relating to the environment shall be defined.
F. Installation of diving system on support vessel or fixed structure F 100 Location 101 Requirements for installation of diving systems on diving support vessels are given in DNV Rules for Classification of Ships Pt.5 Ch.16. When some essential requirements are repeated here, it is in recognition of the possible mobilisation at locations not covered by the DNV Rules for Classification of Ships. Guidance note: For containerised systems, the 2012 edition of DNV Standard for Certification 2.7.2 “Offshore Service Containers” may be used.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 102 Provision should be made to ensure that the diving system and auxiliary equipment are securely fastened to the ship or floating structure and that adjacent equipment is similarly secured. Consideration should be given to the relative movement between the components of the system. In addition, the fastening arrangements should be able to meet any required survival conditions of the ship or floating structure. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.8.3) 103 The diving system and breathing gas storage facilities should not be sited in machinery spaces if the machinery is not associated with the diving system. Where, due to the requirements of diving operations, systems are sited in hazardous areas, the electrical equipment should comply with the requirements for such equipment in hazardous areas. Diving systems should not be permitted in hazardous areas designated as zone O. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.6.6) 104 Piping systems carrying mixed gas or oxygen under high pressure should not be arranged inside accommodation spaces, engine rooms or similar compartments. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.11)
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105 Oxygen bottles should not be stored near flammable substances. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.5) F 200 Physical protection 201 When any part of the diving system is sited on deck, particular consideration should be given to providing reasonable protection from the sea, icing or any damage which may result from other activities on board the ship or floating structure. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.8.2) 202 The diving system shall be so located that surface diving operations shall not be affected by propellers, thrusters or anchors. Information clearly indicating thruster positions, and permissible umbilical lengths, over the operating depth range of the system, shall be posted in Dive Control. Guidance note: Some national regulations will limit the length of umbilicals so that the diver, or his umbilical, cannot be drawn into the propellers or thrusters. Requirements to the use of 'wet-bell' may also apply in some regions. It is assumed that the Operator provides, and follows, an effective umbilical management procedure whenever carrying out surface demand diving operations from a DP vessel.
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F 300 Ventilation and lighting 301 The diving system and breathing gas facilities should be arranged in spaces or locations which are adequately ventilated and provided with suitable electric lighting. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.8.1) Outer area situated in enclosed spaces shall be fitted with separate mechanical ventilation with minimum 8 air changes per hour. 302 Oxygen bottles should be installed in a well-ventilated location. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.4) Containers for oxygen shall be stored in open air or in rooms exclusively intended for oxygen. The rooms shall be separated from adjacent spaces and ventilated according to requirements in Sec.6 and shall be fitted with an audio-visible oxygen alarm, at a manned control station. 303 For SURFACE diving systems installed on support vessels classed as FiFi I, gas storage shall be protected from overheating in the event of fire fighting close to heat radiation. Vessel Class Notation FiFi shall be suspended during diving operations, unless extraordinary measures are implemented. F 400 Electrical power supplies to the installed diving system 401 Equipment in the power supply to essential and emergency consumers, as defined in D300 and D400, see also Sec.5 B500, shall normally be located above the uppermost continuous deck and accessible from open deck. F 500 Structural fire protection 501 Spaces in the interior of ships or floating structures in which the diving system or its auxiliary equipment is carried should be provided with structural fire protection in a way similar to control stations * bounding main zones. * “Control stations” as defined in regulation 3 and referred to in regulation 20, chapter II-2 of the International Convention for the Safety of Life at Sea, 1974. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.9.2) 502 Compliance shall be based on the defined zones as given in the applicable fire integrity table in SOLAS Reg. II-2/9. 503 Vessel Class Notation FiFi shall be suspended during diving operations, unless extraordinary measures are implemented.
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SECTION 3 PRESSURE VESSELS FOR HUMAN OCCUPANCY, GAS STORAGE AND OTHER PURPOSES
A. Introduction A 100 Objectives 101 Pressure vessels are designed and manufactured to internationally recognised codes and standards. The objectives of this section are to give additional requirements that relate to the function of these pressure vessels in a diving system. A 200 Scope 201 The following scope of work is included in the requirements of this section: a) conceptual and detailed design of pressure vessels for human occupancy, for gas storage and for other purposes b) manufacturing of such pressure vessels c) quality control during manufacturing and fabrication of such pressure vessels including documentation requirements d) load conditions e) interlock arrangements for doors and hatches 202 ASME PVHO-1 “Safety Standard for Pressure Vessels for Human Occupancy” shall be used for design of acrylic plastic windows, regardless of which standard is used for the design of the pressure vessel. 203 Welding of pressure vessels and general workmanship requirements are given in the relevant rules, codes and standards. 204 Installation of pressure vessels is specified as general requirements found in Sec.2 F. Further requirements for installation are given in DNV Rules for Classification of Ships Pt.5 Ch.16. A 300 Application 301 This section applies to all pressure vessels in SURFACE diving systems designed to comply with this standard. Note that in addition to this standard, and the applied design standards, further national requirements may apply. 302 “Closed” bells are not required for SURFACE diving systems and consequently not included in the application of this standard. If closed bells are employed, the complete diving system shall comply with the relevant requirements given in DNV-DS-E402. (Note: currently under development, meanwhile use DNV-OS- E402). 303 This section has impact upon Sec.9, insofar as it provides the basis for design of the pressure vessels in the hyperbaric evacuation system. A 400 References 401 For quantitative design parameters and functional requirements, reference is made to relevant standards and guidelines, including normative references given in Sec.1B and DNV Rules for Classification of Ships. 402 All pressure vessels for human occupancy shall be designed, constructed and tested according to one of the following codes and standards: a) EN 13445 “Unfired pressure vessels”. b) ASME PVHO-1, referencing ASME VIII Div.1 or 2 “Boiler and Pressure Vessel Code” 403 Pressure vessels for human occupancy shall be classified in the highest category in the applied code or standard. 404 Other codes and standards may be evaluated and accepted on a case by case basis. 405 All pressure vessels for human occupancy shall be certified, as required in A500. 406 All windows in pressure vessels for human occupancy shall be certified in accordance with ASME- PVHO-1. 407 Gas cylinders shall be designed, constructed and tested according to one of the following standards, norms or directives: a) EN-1964-1 Transportable gas cylinders (part 1:1999, part 2:2001 or part 3:2000)
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.3 – Page 31 b) EN ISO 11120 Gas cylinders - Refillable seamless steel tubes for compressed gas transport, of water capacity between 150 l and 3000 l - Design construction and testing 408 Other codes and standards may be evaluated and accepted on a case by case basis. Guidance note: For permanent installations within EU, the directives apply as regulations. (ref. EU directive 1999/36/EEC.)
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A 500 Procedural requirements, approval and certification 501 Approval and Certification requirements are given in DNV-DSS-105 Appendix A. 502 Pressure vessels shall be produced by manufacturers approved for such production and certified when: where: p = design pressure in bar V =volume in m3 503 Smaller pressure vessels shall be certified if they provide an essential function in the system. Guidance note: Cylinders on-line in a system providing breathing gas to the divers will be considered essential.
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A 600 Documentation 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. Further references with regards to general requirements are given in Sec.2 of this standard. 602 Pressure vessels shall be documented as follows: Plans showing structural arrangement, dimensions, welding seams, attachments and foundations of the chamber and other pressure vessels, with details of doors, locks (medical locks and equipment locks), view ports, penetrations, flanged and welded connections. Plans showing expansion allowances under working conditions for interconnected multi-vessel systems – if applicable. Documents stating: a) Grade of material b) Welding methods, type and size of filler metal c) Design pressure d) Particulars of heat treatment e) Fabrication tolerances f) Extent and type of non-destructive testing of welded connections g) Type of thermal insulation materials and particulars, i.e.: flammability and specific heat conductivity h) Drawings and specifications of all windows with detailed drawings and specifications of the penetration which the appropriate window is to fit. It shall be determined that the tolerances are sufficient including gaskets, O-rings and retainer rings i) Calculations of thicknesses and or stresses j) Fatigue evaluation and if necessary fatigue analysis For seamless steel gas cylinders and vessels: a) Plans showing proposed dimensions and details such as valves and safety devices shall be made for each type and size of vessel. Details shall include: a) Production method b) Heat treatment Material specifications for the completed vessel with information on the following: a) Chemical composition b) Tensile strength
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.3 – Page 32 c) Yield strength d) Elongation e) Impact test values f) Brinell hardness The following particulars shall be provided for information: a) Type of gas b) Filling pressure at 15°C c) Safety Relief Valve setting d) Weight of empty vessel and volumetric capacity e) Material protection A 700 Survey and testing requirements during and after manufacture 701 Requirements and guidance on inspection and monitoring associated with the production of pressure vessels can be found in the applied standard and DNV-RP-E401. 702 For welded pressure vessels the following tests have to be carried out in addition to the tests specified in the applied design code or standard: a) all butt welds in diving chambers shall be radiographed over their full length b) branches and reinforcement of openings, including all weld connections to the shell, shall be subjected to 100% magnetic particle testing 703 When the applied code or standard for welded pressure vessels requires heat treatment of dished ends after hot or cold forming, mechanical testing may be required after the final heat treatment. 704 The details between intermediate heads and cylindrical shells of chambers may be done in accordance with requirements given in, a) EN 1708-1:1999 Welding - Basic weld joint details in steel Table 9:Internal diaphragms and separators, or b) ASME Section VIII - Division I Fig. UW-13.1. 705 Welded pressure vessels and seamless steel gas containers for internal pressure shall be hydrostatic tested to an internal pressure in accordance with the design code. Each compartment in chambers shall be tested separately. In addition pressure test shall be performed with test pressure in each chamber simultaneously. 706 Pressure vessels for external pressure shall, in addition to the internal pressure testing, be hydrostatic tested to an external pressure in accordance with the design code. 707 Acrylic plastic windows shall be tested in accordance with ASME PVHO-1a-Article 7. 708 For seamless gas cylinders production tests shall be carried out in accordance with the requirements given in the applied code or standard. Further production tests, and required attendance during testing, may be given in the specifications. 709 Gas cylinders shall be cleaned and sealed according to accepted industry standards. A 800 Survey and testing requirements during and after assembly 801 The gas storage and chambers shall be tested for leakage at low pressures and the maximum working pressure. A 900 Marking and signboards 901 All gas containers shall be marked with a consistent colour code visible from the valve end, showing the name, chemical formula of the gas it contains and the percentage of each gas. Piping systems shall be marked with a colour code, and there shall be a chart posted in the control room explaining the code.
Table A1 For piping systems and gas storage bottles/pressure vessels the following colour code should be used: Name (Symbol) Colour code Oxygen (O2) White Nitrogen (N2) Black Air (Air) White and black Carbon dioxide (CO2) Grey In addition, each bottle/pressure vessel should be marked with the name and symbol given above of the gases it contains. The marking and colour coding of the gas storage bottles should be visible from the valve end. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.9)
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902 Each gas container shall be permanently and legibly marked on the collar or neck ring (where the thickness of the material is greater than the design minimum) as follows: a) The design code b) the manufacturer's mark or name c) the manufacturer's serial number d) the test pressure (bar) and date of hydrostatic test e) surveyor's mark and identification f) settled pressure (bar) at 15°C g) volumetric capacity of the container, in litres h) tare weight, i.e. the mass of the container including valve, in kg In addition marking of gas content shall be carried out according to Table A1. 903 Other pressure vessels shall be permanently and legibly marked at a suitable location in accordance with the requirements in the design code. As a minimum the following information shall be present: a) The design code b) the manufacturer's mark or name c) the manufacturer's serial number d) the test pressure (bar) and date of hydrostatic test e) the maximum working pressure f) the inspection body’s mark and identification g) the maximum set pressure of the Safety Relief Valves A 1000 Materials 1001 Material specifications and selection associated with the production of pressure vessels are given in the applied codes and standards (EN/ASME) and/or in DNV Rules for Classification of Ships. 1002 Areas of steel pressure vessels that can be subjected to corrosion shall be protected by approved means. 'The surface of the window seats cavity shall be protected against corrosion. 1003 Windows mounted on chambers shall be protected to avoid damage by impact and to prevent chemicals, which can deteriorate the acrylic plastic, to come in contact with the window from the outside. Guidance note: Many solvents for paints, acetone and other agents will deteriorate the acrylic plastic and reduce the strength significantly.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 1004 All penetrators in pressure vessels for human occupancy shall be designed to minimise corrosion from any fluid passing through them. Guidance note: In some cases this requirement may best be met by the use of a sleeve passing through the hull penetration.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 1005 Paints, cabling and other materials shall be considered for toxic or noxious properties.
B. General Principles for Design of Chambers B 100 General 101 A diving system should, as a minimum, include either one surface compression chamber with two separate compartments, or two interconnected separate chambers so designed as to permit ingress or egress of personnel while one compartment or chamber remains pressurized. All doors should be designed so that locking mechanisms, if provided, can be operated from both sides. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.2.1) 102 Where a surface compression chamber is to be used (-omitted, non-applicable text-), it should be so arranged as to allow most divers to stand upright and to stretch out comfortably on their bunks. The smaller of the two compartments should be large enough for at least two persons. One of these compartments should be a living compartment. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.2.2).
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For SURFACE diving systems the minimum inner dimensions measured as free height above the deck plates in the middle of the chamber, shall be 170 cm This may be less if the chamber is only used for stand-by purposes and if national regulations allow it. Guidance note: Statutory requirements may require larger dimensions.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 103 A surface compression chamber should provide a suitable environment and facilities for the persons who use it, having regard to the type and duration of the diving operation. (-Omitted, non-applicable text-). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.2.6) 104 Wet-bells, if employed, and SURFACE diving baskets shall be of adequate size, be equipped to cater for the number of divers intended to man them and be equipped for handling unconscious or injured divers. B 200 Design loads 201 The design pressure for pressure vessels shall not be less than that corresponding to the maximum operating pressure as defined in the specifications given in the MPS. 202 The design load is normally to correspond to the design pressure applied for at least 5000 load cycles unless otherwise agreed and specified. 203 The effects of the following loads shall be considered and shall be taken into account - if significant. Reference is given to DNV Rules for Ships Pt.3 Ch.1 Sec.3 (Principles) & Sec.4: a) Dynamic loads due to movements of the support vessel b) Local loads c) Loads due to restrictions in expansions d) Loads due to weight of content during normal operation and pressure testing e) Loads due to rough handling f) The stress evaluation shall apply the distortion theory (von Mises’ criterion) Guidance note: Multipurpose vessels may carry relatively heavy deck loads, which can cause stresses and strains on the mountings of the diving system components. If this cannot be avoided through design of the installed diving system, it should be monitored during such operations.
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B 300 Foundations for pressure vessels for human occupancy and for gas storage 301 The pressure vessels with foundations shall be designed for a static inclination of 30° in any direction without exceeding the allowable stresses as specified in the design code. 302 Suitable foundations and supporting structures shall be provided to withstand a collision force acting on the pressure vessels corresponding to one half the weights of the pressure vessels in the forward direction and one quarter the weight of the pressure vessels in the aft direction. 303 The loads mentioned in 201 and 202 need not to be combined with each other or with wave-induced loads. B 400 Doors, hatches, windows, branches etc. 401 The living compartment and other compartments intended to be used for decompression should have a lock through which provisions, medicine and equipment may be passed into the chamber while its occupants remain under pressure. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.2.3) 402 Doors and hatches for human transportation shall in general be a minimum diameter of 600 mm. Guidance note: For doors and hatches in between chambers, standard pipe with nominal bore 24" may be acceptable.
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403 The medical locks shall be large enough to allow lock-in and lock -out of CO2 absorption material and necessary supplies for the divers. Guidance note: National rules and requirements may be more stringent and thereby take precedence (i.e. Norwegian Petroleum Directorate).
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404 Means enabling the doors to be opened from either side shall be provided. Guidance note: As the above requirement also applies to the internal doors in chambers, it does follow that locking devises are not allowed on the pressurised side of these doors unless they can be operated from the other side. 'Clip' locks are frequently used on these doors to prevent slamming due to the vessels movement in the sea. However, the 'clip' setting must be such that they can be pushed/pulled open from either side without the use of excessive force.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 405 Locks should be designed to prevent accidental opening under pressure and, where necessary, interlocks should be provided for this purpose. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.2.4) 406 For: a) doors b) hatches c) mating arrangements d) pressurised locks and trunks e) pressurised containers f) accompanying equipment under pressure where opening or unintentional pressure drop may entail danger or cause injury, the closing mechanisms shall be physically secured by locking mechanisms (interlocks). This applies to units which do not seal by pressure and includes, but is not limited to: a) equipment locks b) medical locks c) soda lime (CO2 scrubber) containers for external regeneration of the chamber environments (if fitted) d) mating arrangements between hyperbaric evacuation units and escape trunks where these are installed 407 The closing mechanisms with accompanying locking mechanisms shall be arranged so that: a) opening cannot take place unless the pressures are equal on both sides or unless the pressures in the units are at ambient level b) correct position of the closing mechanisms and the locking mechanisms shall be ensured before it is possible to apply pressure c) the pressures in the units, shall directly control the locking mechanisms, and d) the penetrators and piping for pressure sensing shall be arranged so that blockage is avoided Guidance note: Reference is given to ASME PVHO-1 with sub reference to ASME VIII D1 UG-35.2(b)(1) and EN 13445-5 C.5.7.3.2.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 408 Trunks between doors shall be equipped with pressure equalising valves. Penetrators for pressure equalising shall be arranged so that blockage is avoided. 409 Each pressure compartment should have view ports to allow observation of all occupants from the outside. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.2.5) 410 Windows shall be protected against impact. Impact protection may be provided by: a) recessing the external surface of the window at least 50 mm below the surrounding structure b) one or more external bumpers extending across the window 411 Where mountings are secured by studs, these shall have full thread holding in the shell for a length of at least one diameter. Holes for studs shall not penetrate the shell. 412 Damage control plugs may be provided to enable the divers to seal off windows to prevent damage or leakage developing. 413 For pressure vessels where fatigue can be a possible mode of failure, attention shall be given to the possible adverse effects of the following design features: a) pad type reinforcement of openings b) set-on branches
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.3 – Page 36 c) partial penetration welds of branches 414 For structures that are not covered by the pressure vessel design code, the butt weld and filled weld shall be designed to take shear based on 1.5 times the maximum differential pressure that can exist. The allowable stress value for the butt weld shall be 70% of the nominal design stress for the shell material and that of the fillet weld 50%. The area of the butt weld in shear shall be taken as the width at the root of the weld times the length of the weld. The area of the fillet weld shall be taken as the minimum leg dimension times the length of the weld.
C. Welded Pressure Vessels, Materials, Fabrication and Strength C 100 Materials 101 Steel grades shall comply with the applied design code and standard. 102 Other material grades may be acceptable after special consideration. In such cases, additional testing may be required and qualification procedures shall be reconsidered. 103 Materials for main pressure retaining parts are to be certified. 104 Stainless steel cladding, stainless steel tubes, fittings etc. which are welded to pressure vessels of non- stainless steel shall be of a stabilised or low-carbon grade. Acceptable grades are given in the applicable standards or in DNV Rules for Classification of Ships Pt.2 Ch.2 Sec.4. C 200 Fabrication 201 Pressure vessels for diving systems shall be manufactured by works approved by a recognised body, for the production of the type of pressure vessels being delivered. For systems classed by the Society, this shall be according to the Society’s approval programme. 202 Welding shall be carried out according to approved drawings. Qualification of welders, welding procedure specifications, welding procedures and testing shall be according to the applied design code or standard. 203 The outside diameter of the head skirt shall have a close fit to the cylinders. 204 The surface dimensions and finish of seals for hatches and windows are generally to comply with the tolerances specified by the manufacturers of the windows and the sealing systems. The fitting and installation of the window to the flange shall be according to the requirements given in ASME PVHO-1. C 300 Fabrication tolerances 301 Fabrication tolerances are to meet the requirements in the applied codes and standards. 302 Local tolerance requirements for ring frames are given in DNV-DS-E402 Sec.3 (Note: currently under development, meanwhile use DNV-OS-E402), for vessels subject to external pressure – if applicable. C 400 Structural analysis to determine strength 401 In the design of pressure vessels including accessories such as doors, hinges, closing mechanisms and penetrators, the effects of rough handling and accidents should be considered in addition to design parameters such as pressure, temperature, vibration, operating and environmental conditions. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.5) 402 Pressure vessels shall be documented by structural analysis for specified design conditions according to the applied codes and standards. 403 For details not covered by the applied codes and standards, finite element analysis may be acceptable if properly planned, modelled and documented. Alternatively, by applying strain gauges, stress measurements may be carried out according to an approved programme and shall be properly documented. The tests shall be planned, and carried out during the first pressure test. 404 Fatigue evaluation and, if necessary, fatigue analysis shall be carried out for the number of full pressure cycles and non-pressure loads given in the specification. The evaluation and analysis shall be carried out according to the applied design code and standard. Reference is given to DNV Rules for Ships Pt.3 Ch.1 Sec.3 (Principles) & Sec.4. C 500 Strength of vessels subjected to external pressure 501 Refer to DNV-DS-E402 Sec.3 if applicable. (Note: currently under development, meanwhile use DNV- OS-E402) C 600 Flanges for windows 601 Flanges for windows with conical seating shall have dimensions preventing the flange deformations to exceed the following limits when window and pressure vessel is subjected to the design pressure:
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.3 – Page 37 a) radial: 0.002 times the smaller diameter of the acrylic plastic window, and b) angular: 0.5°
D. Gas Cylinders D 100 General 101 The materials applied in the manufacture of gas cylinders shall be certified. 102 Special attention should be paid to the design and choice of material for the construction of pressure vessels containing oxygen. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.4.1) 103 Shell thickness shall meet the criteria given in the applied code or standard for test pressure. The working pressure for a given geographical area is given by reference to a standard such as BS 5355 Specification for filling ratios and developed pressures for liquefiable and permanent gases. 104 Corrosion allowance shall be specified in the terms of delivery reflecting the intended use of the gas cylinder, but shall not be less than 1 mm. D 200 Heat treatment 201 Heat treatment shall follow the requirements given in the applied code or standard, and shall be documented. D 300 Tolerances and surface conditions 301 Tolerances and surface condition shall meet the criteria given in the applied code or standard, and shall be documented in the design documentation. If the applied code or standard does not specify requirements for tolerances and surface conditions, then it may be necessary to specify this in the diving systems specifications.
E. Acrylic Plastic Windows E 100 General 101 The following requirements apply to windows made from cast stock of unlaminated polymethyl methacrylate plastics, in the following denoted acrylic plastic, with a design life of 10 years, suitable for: a) 10.000 load cycles b) sustained temperatures in the range specified by the end user and not less than specified by ASME PVHO-1 c) pressurisation or depressurisation rates not exceeding 10 bar/second d) use in environments that cannot cause chemical or physical deterioration of the acrylic plastic (i.e. resistant against saltwater and gases used in life support systems) E 200 Materials 201 Materials for acrylic plastic windows shall be manufactured and tested in accordance with ASME PVHO-1 “Safety Standard for Pressure Vessels for Human Occupancy”. E 300 Manufacturers of cast material 301 Manufacturers wishing to supply cast acrylic plastic for diving systems, shall be approved for such production. The material shall have an approved chemical composition and to be produced, heat treated and tested according to the ASME PVHO-1 “Safety Standard for Pressure Vessels for Human Occupancy”. Approval shall be granted on the basis of a thorough test of material from the current production and a report after inspecting the works, and verification of QA and QC against requirements given in ASME PVHO-1. E 400 Certification of cast material 401 Each delivery of cast material shall be accompanied by a certificate issued by the manufacturer. The certificate shall (as a minimum) contain the following: a) name and address of manufacturer b) certificate number and date c) designation of product d) numbers and dimensions of the pieces covered by the certificate e) material test results and properties f) signature
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402 The following text shall be printed in the right uppermost corner of the certificate: “This certificate will be accepted by (approval body) on the basis of completed approval tests and the (approval body’s) surveillance of production control and products. The manufacturer guarantees that the product meets the requirements of (approval body) and that inspection and tests have been carried out in accordance with (code or standard)”. 403 The cast material shall be marked with the manufacturer's name and with the number and date of the certificate. 404 If a later edition of the ASME standard requires further documentation and markings, the ASME requirements shall be met. E 500 Certification of windows 501 Each batch of acrylic plastic windows used in diving systems shall have a certificate issued by the approval body, showing the test results and the annealing conditions according to the applicable forms given in ASME PVHO-1. 502 Each window shall have an identification marked on it for traceability. Identification of each window shall include; design pressure, maximum temperature, initials for 'P.V.H.O.', window fabricator's identification mark, fabricators serial number and year of fabrication. 503 For ease of viewing, the above information shall be located on the windows seating surface with an indelible marker. Acceptable marking methods are given in ASME PVHO-1. 504 Stamping or marking that can cause crack propagation is not permitted. E 600 Geometry and thickness 601 Windows shall be of the standard designs according to the ASME PVHO-1 “Safety standard for pressure vessels for human occupancy”. 602 O-ring grooves shall not be located in window bearing surfaces serving primarily as support or in the acrylic window itself. E 700 Fabrication 701 The included conical angle of the seating surface of a window shall be within +0.25/ -0,00 degrees of the nominal value. 702 The deviation of a spherical window from an ideal sphere shall be less than 0.5% of the specified nominal external radius of the spherical section. 703 Each window shall be annealed after all forming and polishing operations are completed. The annealing process shall be according to the annealing schedule in ASME PVHO-1. 704 During the manufacturing process each window shall be equipped with identification and a manufacture process rider for recording of all pertinent data. E 800 In service inspection 801 In service inspection and testing shall be carried out in accordance with requirements given in ASME PVHO-2 guidelines.
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SECTION 4 LIFE SUPPORT SYSTEMS INCLUDING PIPING, HOSES, VALVES, FITTINGS, COMPRESSORS AND UMBILICALS
A. Introduction A 100 Objectives 101 The objectives of this section are to specify requirements for life support systems, including pipes hoses valves, fittings, compressors and umbilicals, serving SURFACE diving systems. General requirements for piping systems are given in DNV Rules for Classification of Ships Pt.4 Ch.6. A 200 Scope 201 Requirements for installation are given in Sec.2 F. 202 This section is giving guidance on: a) conceptual and detailed design of life support systems b) manufacturing of life support systems c) quality control during manufacturing and fabrication of components and subsystems for life support systems 203 Key issue requirements for gas distribution capacities, environmental conditioning and oxygen systems. 204 Design and acceptance criteria including capacities for gas storage, choice of valves and fittings for certain applications, environmental control parameters and breathing resistance for CCBS (if fitted). 205 Requirements for the design of oxygen systems aimed at reducing the hazards posed by flash fires. 206 Limitations on the use of hoses except hoses used in umbilicals are given. 207 Requirements to ensure safe arrangements in pressurised systems and control stations and requirements for pipes, hoses, valves and fittings are given. 208 Requirements for shut off valves, pressure relief and drainage aimed at ensuring the safeguard of personnel and plant, as are the requirements for alarm systems. A 300 Application 301 This section applies to all SURFACE diving systems. 302 This section has an impact on all other sections in this standard. This section applies to all systems essential for the safe operation of the diving system. A 400 References 401 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16 and Sec.2 F of this standard. 402 Manufacturing standards applicable to individual components shall be supplementary to this standard. 403 Further references are given to: a) DNV Rules for Classification of Ships Pt.4 Ch.6. b) DNV Rules for Classification of Ships Pt.5 Ch.16 c) EN 738-1, -2 and -3:1997/1998 “Pressure regulators for use with medical gases” d) EN 849:1996, EN ISO 11114-3:1997 and EN ISO 2503:1998 (informative) e) DNV-DS-E402 (Note: currently under development, meanwhile use DNV-OS-E402) f) ASTM G93 Standard Practice for Cleaning Methods and Cleanliness Levels for Materials and Equipment Used in Oxygen-Enriched Environments A 500 Procedural requirements, approval and certification 501 Approval and Certification requirements are given in DNV-DSS-105 Appendix A. A 600 Documentation requirements 601 Life support systems shall be documented as follows: a) Plans showing schematic arrangement of all piping systems. b) Documents stating:
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i) material specifications ii) maximum working pressure iii) dimensions and thickness iv) contained fluids v) type of valves and fittings vi) specifications of flexible hoses c) Component lists, with specifications on make and type and documentation on any tests carried out on all equipment used in the life support system. Plans showing cross-section and giving particulars on materials and dimensions of umbilical. d) Plans (diagrams) showing arrangement and giving specifications of the gas storage and supply (gas banks, compressors, boosters etc.). e) Plans showing the arrangement and giving specifications on environmental control systems and equipment (heating, CO2-absorption, circulation), diving crew facilities and drainage systems. f) Determination showing the heat and cooling consumption for the system under specified environmental temperatures. g) Description of proposed cleaning procedure for breathing gas system.Pipes, Hoses, Valves, Fittings, Compressors and Umbilicals shall be documented as follows: h) Plans and specifications showing suitability of the Flexible hose in relation to its intended use. For information, documentation of tests which have been carried out, as required. i) Plans and specifications giving particulars of Umbilical conductors, minimum breaking load and minimum diameter of pulley and drums. For information, specification of max. design loads, elastic properties and weight per unit length. j) Documentation of tests verifying the properties listed above and as required by K. A 700 Survey and testing requirements during and after manufacture 701 In addition to the test requirements here, detailed requirements are found in DNV-RP-E401. 702 Testing during manufacture shall be in accordance with applicable manufacturing codes for the particular component. 703 In systems conducting oxygen, all materials in contact with this gas shall be oxygen shock tested according to EN 738-1, -2 and -3:1997/1998 “Pressure regulators for use with medical gases” or equivalent standard applicable to the particular component. (See also EN 849:1996, EN ISO 11114-3:1997 and EN ISO 2503:1998 in informative references) 704 For piping systems of copper, copper alloys and austenitic steels with chromium-nickel content above 22%, the test can be waived. Guidance note: Oxygen pressure shock tests are described in the standards referred to. However, the test includes the following principles: Commercial grade oxygen (99% pure) test gas is applied as follows for 3 identical test specimens: The test pressure is not less than the design pressure. The test specimen is preheated to 60°C and exposed to a gas pressure shock up to the specified test pressure with test gas preheated to 60°C. Each test consists of 20 pressure shocks at approximately 30 seconds intervals. The total exposure time to each pressure shock is 10 seconds, and the gas pressure is released after each shock. The pressure increase rate during each pressure shock is obtained by a valve with an opening time less than 10 milliseconds.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 705 Compressors shall be tested for the gas types, pressure and delivery rate intended. The tests shall incorporate measurements of humidity and possible, contaminants in the gas delivered. 706 Compressor components subjected to pressure shall be hydrostatic tested in accordance with the design code. 707 Closed circuit breathing system (CCBS – if fitted) shall be tested according to DNV-DS-E402. (Note: currently under development, meanwhile use DNV-OS-E402). 708 Flexible hoses shall be tested as specified in F. 709 Umbilicals shall be tested as specified and as follows: a) Each hose for use in umbilical shall be pressure tested to 1.5 times the design pressure before fitting in the umbilical. After hose end fittings have been mounted, a gas leakage test to design pressure shall be performed.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.4 – Page 41 b) A pressure test to the design pressure of all hoses simultaneously and verification of the specified properties by insulation tests of electrical conductors as well as impedance measurements of signal cables to specified properties shall be carried out. c) Samples of the completed umbilicals shall be tested according to a manufacturer’s test programme complying with relevant requirements in the design code. d) The test programme shall as a minimum include tensile testing and fatigue testing to 5000 load cycles without the umbilical showing any sign of permanent deformation of electrical conductors and or significant permanent deformations of other parts. A 800 Survey and testing requirements during and after assembly 801 Hydrostatic testing of piping systems shall be in accordance with the technical requirements and as for corresponding pipe class in breathing gas systems pertaining to Class I piping systems. 802 Piping for the life support systems shall be pressure tested to 1.5 times the maximum working pressure. Hydraulic systems may, however, be tested to the smaller of 1.5 times the maximum working pressure, or 70 bar in excess of the maximum working pressure. 803 Piping systems conducting gas in life support systems shall be cleaned in accordance with an approved cleaning procedure conforming to requirements given in ASTM G93-96 Standard Practice for Cleaning Methods and Cleanliness Levels for Materials and Equipment Used in Oxygen-Enriched Environments 804 Piping systems intended to be used in breathing gas and oxygen systems shall be tested for purity in accordance with requirements given in ASTM G93-96. The tests shall comprise: a) measurement of contamination of the cleaning agent used at the last stage of the cleaning b) tests for possible traces of cleaning agents left in the piping system 805 The gas storage and life support systems for gas shall be tested for leakage at low pressures and the maximum working pressure. 806 Life support systems for normal and emergency operation shall be tested for proper functioning. This includes: a) sanitary b) diver heating 807 For the environmental control and monitoring system the failure conditions shall be simulated as realistically as possible, if practicable by letting the monitored parameters pass the alarm and safety limits. Alarm and safety limits shall be checked. 808 For the automatic control systems the normal alterations of the parameters shall be imposed and the functions of the system tested. A copy of the approved test program shall be completed with final set points and endorsed by the Surveyor. A 900 Survey and testing requirements during and after installation 901 Support systems on-board the surface installations, significant for the safety of the diving system, are also to be tested. 902 During the sea trials the normal launch and recovery system will be tested to the maximum depth. For SURFACE diving systems employing a “wet-bell” the life support systems shall be checked for leakage. A 1000 Materials, including components for gases containing elevated oxygen levels 1001 Materials used in the breathing gas system shall not produce noxious, toxic or flammable products. 1002 Precautions shall be taken to avoid galvanic corrosion. 1003 Non-metallic materials retaining pressurised gas shall be considered for gas-permeability. 1004 Oxygen and gases with an oxygen volume percentage higher than 25 per cent should be stored in bottles or pressure vessels exclusively intended for such gases. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.4.2) 1005 Piping systems containing gases with more than 25 per cent oxygen should be treated as systems containing pure oxygen. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.5.15) 1006 All materials used in oxygen systems should be compatible with oxygen at the working pressure and flow rate. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.5.7) Materials and components fitted in oxygen systems shall be of types especially designed and tested for this purpose.
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1007 The use of high-pressure oxygen piping should be minimized by the fitting of pressure reducing devices, as close as practicable to the storage bottles. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.8) The pressure in the oxygen systems shall be reduced at storage to the minimum pressure necessary for proper operation. Guidance note: A maximum pressure of 40 bar will normally be accepted.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 1008 Hoses for oxygen should, as far as practicable, be of fire-retardant construction. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.10) 1009 Oxygen systems with pressure greater than 1.72 bar must have slow opening shutoff valves except pressure boundary shutoff valves. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.16) Shut-off valves for oxygen shall be of types which need several turns to close. On chamber penetrators, ball valves may be accepted for emergency use only. 1010 Oxygen dumped from the diving system shall be ducted to a safe dumping place.
B. Gas Storage B 100 Capacity 101 There shall be a permanently installed gas storage plant or suitable space for portable gas containers. The size of the containers or space shall be sufficient to provide the divers with adequate quantities of gases for operation at maximum operating depth for both normal and emergency modes. 102 The minimum gas storage capacity of fixed installed gas containers or space for portable gas containers intended for emergency operations shall be sufficient to: a) Pressurise the inner area twice and the transfer compartments once more to maximum depth, dmax, with suitable breathing gas, and ventilate the chamber as required b) maintain a proper oxygen partial pressure in the inner area and supply for masks for at least 24 hours. For pure oxygen, the minimum volume may be taken as 2 Nm3 for each diver where 1 Nm3 is given as 1 cubic metre of the gas at 0°C and 1.013 bar standard condition. c) conduct two emergency dives to dmax 103 For emergency use of masks required by 102b) there shall be sufficient facilities to supply adequate quantities of gases. The facilities shall be capable of providing a relevant delivery rate both at maximum depth and during decompression. Adequate quantities shall be determined for the applicable operation, but not less than 2 m3 at the pressure of the inner area with an oxygen partial pressure between 0.18 and 1.25 bar for each diver. 104 The storage capacity for emergency gas shall be provided in separate containers, and shall not be included in the containers for current gas supply. 105 If applicable, the wet-bell shall have self-contained emergency gas storage with a minimum capacity to supply the divers for the duration of their in-water stops prior to surfacing. B 200 Shut-off, pressure relief and drainage 201 All surface compression chambers and diving bells which may be pressurized separately should be fitted with overpressure alarms or pressure relief valves. If pressure relief valves are fitted, a quick-operating manual shut off valve should be installed between the chamber and the pressure relief valve and should be wired opened with a frangible wire. This valve should be readily accessible to the attendant monitoring the operation of the chamber. All other pressure vessels and bottles should be fitted with a pressure relief device. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.5) 202 Pressure vessels shall be fitted with over pressure relief devices and shut off valves. 203 Pressure vessels without individual shut-off valves and with: pV < 50, installed in groups with a total pV < 100, can have a common overpressure relief device and shut-off valve. p = design pressure in bar V = volume in m3 (standard conditions) 204 For gas storage of breathing gases and oxygen, the pressure relief device shall be a safety valve. Safety valves shall be set to open at a pressure approx. 3% above the developed pressure at 55°C, based on filling the cylinders at 15°C to maximum filling pressure. The total relieving capacity shall be sufficient to maintain the system pressure at not more than 110% of design pressure. Developed pressure under above-mentioned
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.4 – Page 43 conditions may be taken as given in reference to a standard such as BS 5355 Specification for filling ratios and developed pressures for liquefiable and permanent gases. 205 Containers where water can accumulate shall be provided with drainage devices. (E.g. volume tanks and filters).
C. Gas Distribution and Control System C 100 General 101 Each surface compression chamber and diving bell should be fitted with adequate equipment for supplying and maintaining the appropriate breathing mixtures to its occupants at all depths down to maximum operating depth. When adding pure oxygen to the chamber, a separate piping system should be provided. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.1) 102 In addition to the system mentioned in 2.6.1 each surface compression chamber (-omitted, non- applicable text-) should contain a separately controlled built-in breathing system for oxygen, therapeutic gas or bottom mix gas with at least one mask per occupant stored inside each separately pressurized compartment and means should be provided to prevent any dangerous accumulation of gases. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.2) In addition to the above stipulated masks, there shall be one spare mask installed in each compartment. 103 The gas distribution system consists of all components and piping necessary for distribution of gas for normal and emergency operations. 104 Piping for gas and electrical cables shall be separated. 105 Filters and automatic pressure reducers shall be so arranged that they can be isolated without interrupting vital gas supplies. 106 Valves in piping systems to masks, and divers in water shall be so arranged that: a) leaking valves cannot cause unintentional gas mixtures b) oxygen cannot unintentionally be supplied to other piping systems than that intended for oxygen 107 Gases vented from the diving system should be vented to the open air away from sources of ignition, personnel or any area where the presence of those gases could be hazardous. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.13) C 200 Control stands 201 Requirements for instrumentation are given in Sec.8. 202 The control stands shall have means for: a) choice between gas storage containers b) pressurising and pressure regulation of each compartment independently c) decompression of each compartment independently d) equalising the pressure between compartments e) controlling oxygen and mix gas supply to masks in each individual compartment f) controlling gas supply to the divers and the wet-bell if applicable C 300 Basket and wet-bell (if wet-bell is employed) 301 The diving bell should be designed with a self-contained breathing gas system capable of maintaining a satisfactory concentration of breathing gas for the occupants for a period (-omitted, non-applicable text-) at its maximum operating depth. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.3) 302 There shall be two independent supplies of gas to the divers and, if applicable, the wet-bell umbilical. 303 The diver(s) shall have, in addition to their normal umbilical supply, an independent self-contained emergency supply from the basket or wet-bell. The emergency supply in a basket may be by means of reduced air from a cylinder mounted in the basket. 304 The breathing gas system supplying the personal umbilical to the stand-by diver in the wet-bell, when wet-bell is employed, shall be arranged for an alternative supply, independent of the lock-out diver(s)'s normal supply. The wet-bell’s on-board gas supply may be accepted for this purpose. 305 The wet-bell, if employed, shall be equipped with a valve operated exhausts and shall be fitted with a spring-loaded valve that closes when the valve handle is released. 306 The wet-bell shall be equipped with masks corresponding to the number of divers plus one. The masks
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.4 – Page 44 shall be arranged for supply from normal and emergency supply alternatively. Diving masks and diving helmets with gas supply are accepted as masks. C 400 Chambers 401 The distribution system to each compartment shall facilitate: a) two independent alternatives for pressurisation with a minimum pressurisation rate of 2 bar/minute to 2 bar and at 1 bar/minute thereafter b) depressurisation with a decompression rate in accordance with specified decompression tables (e.g. US NAVY diving tables) c) maintenance of a suitable breathing atmosphere in the inner area d) supply of suitable breathing gas for masks e) exhaust from masks intended for oxygen if a closed circuit breathing gas system is not used 402 Each compartment shall be equipped with breathing masks corresponding to the maximum number of divers for which the chamber is rated plus one. Other compartments shall have at least 2 masks. 403 The masks shall be permanently connected or easily connectable to piping systems for supply of the gases according to B103. 404 The exhaust sides of the masks intended for oxygen shall be connected to external dump, or to be of a closed circuit type. 405 The mask systems shall be secured against inadmissible pressure drop on the exhaust side. 406 The gas supply system shall be arranged to ensure homogenous gas content in the inner area. C 500 Stand-by diver at surface 501 A system for supply of life support to a stand-by diver at surface shall be arranged independent from the divers' supply, and shall meet the requirements for the normal diver’s supply. C 600 Nitrogen/oxygen mixing systems for direct supply for breathing 601 Systems for mixing of nitrogen and oxygen for subsequent direct supply for breathing shall be automatic, to have an automatic control system, an automatic alarm system and an automatic safety system. 602 The safety system shall be independent of the control system and shall incorporate changing of the supply automatically to a premixed suitable breathing gas if tolerances are exceeded. The safety system shall ensure a constant delivery of suitable breathing gas to the diver during all operating conditions, taking into account the characteristics of components in the systems such as response time for gas analysers etc. 603 As an alternative to 602, the inclusion of a large volume tank is considered to provide an equivalent level of safety as that prescribed by the requirements for 'automation' and 'independence'. The remaining requirements shall be met. The volume tank shall be such that the prescribed tolerances for partial pressures downstream are not deviated from within the first hour after the analysers have alerted the operator that the upstream mixture is out of the tolerated range. The Alarm shall be audio-visual at a manned control station. 604 The control system shall keep the mixture at a pre-set value within prescribed tolerances. Maximum tolerances: +/- 0.03 bar, partial pressure O2. 605 If the mixing system is arranged as a closed circuit breathing system (CCBS), it shall meet the requirements for such systems given in DNV-DS-E402 (Note: under development, meanwhile use DNV-OS- E402 Sec.4).
D. Diver’s Heating and Environmental Conditioning in Chambers D 100 General 101 A diving system should include adequate plant and equipment to maintain the divers in safe thermal balance during normal operations. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.6.7) D 200 Heating of divers in the water 201 Divers may employ insulated suits and not require active heating. In this case, calculations, or vendor information, shall be submitted for information. 202 When required, the divers shall have a normal heating system with controls and capacity sufficient to maintain given temperatures for the divers in the water according to specified diving tables. The heating system shall be fitted with a temperature indicator.
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D 300 Heating and cooling of chambers 301 Systems for heating the living compartments shall be arranged when required according to environmental criteria given in the specifications. 302 Heating coils on the outside of the chambers shall have a minimum of two independent temperature controls of the power circuit. D 400 Noise reduction 401 Pipe systems should be so designed as to minimize the noise inside the diving bell and surface compression chamber during normal operation. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.1) 402 Silencers shall be fitted and the system shall be so designed that the divers cannot be exposed to harmful noise levels. Guidance note: IMO resolution A.468 (XII) code on noise levels on-board ships.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 403 Silencers shall be fitted with shields which provide protection against possible fragmentation but which do not affect the gas flow. D 500 Gas circulation systems for chambers 501 Internal circulation systems for gas in the chambers shall be such that homogeneous gas content is ensured. 502 Pressurising and exhaust systems shall be arranged to ensure an even mixing of gas. 503 The circulation system shall have sufficient capacity to maintain a homogenous gas mix at the set operational parameters. 504 Materials shall be considered for toxic or noxious properties. D 600 Removal of carbon dioxide 601 Carbon dioxide removal systems shall be arranged for each living compartment and shall have the capacity to maintain the partial pressure of carbon dioxide below 0.005 bar continuously based on a production rate of 0.05 Nm3 per hour per diver. For two divers’ occupancy, this requirement may be met by flushing the chamber atmosphere providing the maximum noise levels are not exceeded.
E. Piping Systems E 100 General 101 All high-pressure piping should be well protected against mechanical damage. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.14) 102 Piping systems shall comply with the technical requirements for Class I piping systems in DNV Rules for Classification of Ships Pt.4 Ch.6. 103 Welding of joints shall be carried out by qualified welders using approved welding procedures and welding consumables. Technical requirements are given in DNV Rules for Classification of Ships Pt.2 Ch.3. 104 Where applicable the following requirements given in DNV Rules for Classification of Ships Pt.4 Ch.6, shall be followed: a) bending and welding procedures b) welding joint particulars c) preheating d) heat treatment after welding and forming e) non-destructive testing and production weld testing f) bracing of copper and copper alloys 105 Piping systems which may be subjected to a higher pressure than designed for should be fitted with a pressure relief device. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.6) 106 Low-pressure systems supplied from high-pressure system shall be provided with pressure relief valves. The total relieving capacity shall be sufficient to maintain the system pressure at not more than 110% of design pressure. The relief device shall be located adjoining, or as close as possible, to the reducing valve.
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107 All systems shall be provided with means of manually relieving the pressure. 108 Filters shall be provided on the high-pressure side of gas systems.
F. Hoses F 100 General 101 Flexible hoses, except for umbilicals, should be reduced to a minimum. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.9) 102 Flexible hoses shall not replace fixed piping. 103 In addition to umbilicals, short lengths (up to 2 m) of flexible hose may be used when necessary to admit relative movements between machinery and fixed piping systems. For assemblies incorporating specially approved hoses and securing arrangements, lengths up to 5m may be permitted if fixed piping is not practicable. In such cases, securing arrangements shall be in place at 1m intervals of the length of the hose. In addition to the couplings, the hoses shall be secured in such a way as to prevent the hose from whip lashing in the event that the coupling fails. When applicable, couplings shall incorporate bends so that kinks in the hoses are avoided. 104 Flexible hoses with couplings shall be certified. For diving systems classed by the Society, the approval shall be according to DNV Rules for Classification of Ships Pt.4 Ch.6. 105 The bursting pressure of synthetic hoses shall be according to Standard for Certification No. 2.9 TA programme 5-791.70 and 5-791.80. 106 Hot water hoses shall be designed for conveyance of fluids of temperatures not less than 100°C 107 Flexible metallic hoses shall comply with ISO 10 380, BS6501 or equivalent. These types of hoses shall not be installed in systems subject to excessive vibrations or movements. 108 Flexible synthetic hoses shall comply with SAE J 517, DIN EN 853, 856, 857 or equivalent. The internal oil resistance test may be omitted for hoses intended for gas and water only.
G. Valves G 100 Valve design 101 Pressure ratings for valves shall be in accordance with a recognised national standard. 102 Design and arrangement of valves shall be such that open and closed positions are clearly indicated. 103 Valves are normally to be closed by clockwise rotation. G 200 Chamber valves 201 Exhaust lines should be fitted with an anti-suction device on the inlet side. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.12) 202 All pipe penetrations on chambers should be fitted with two shut off devices as close to the penetration as practicable. Where appropriate, one device should be a non-return valve. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.4) 203 All pipe penetrations in the chambers shall be fitted with external and internal shut-off valves mounted directly on the shell plating. Valves may be mounted close to chamber shells, provided that the piping between the chamber and valve is well protected and has a minimum thickness according to the rules. 204 In addition to the requirements in 203 all penetrations for lines designed for gas distribution (e.g. supply, exhaust and equalisation) shall be fitted with non-return valves or flow fuses as appropriate for the direction of gas flow. Lines specifically designed for non-distribution purposes (e.g. analysis) shall be kept to the minimum internal diameter possible and limited to a maximum of 5 mm. 205 The piping between externally mounted non-return valve or flow-fuse and the external shut-off valve shall be well protected and have minimum thickness according to E. 206 The compartments shall be fitted with a safety relief valve or a visual and audible overpressure alarm alerting the operators at the control station. National standards and/or regulations may stipulate requirements for safety relief valves, and shall be followed in these cases. 207 Penetrations for safety valves shall be provided with shut-off valves on both sides of the shell plating. These shut off valves shall be sealed in the open position. Any safety valves shall be set to open at a pressure of approx. 3% above the design pressure. 208 Valves in chambers designed for holding water (i.e. hyperbaric training centres) shall be considered in each case.
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H. Fittings and Pipe Connections H 100 Detachable connections 101 Bite and compression type couplings and couplings with brazing, flared fittings, welding cones and flange connections shall be designed according to a recognised standard.
I. Pressure Regulators I 100 General 101 Pressure regulators shall have more than one full rotation from fully closed to fully opened position. 102 Automatic pressure reducers for breathing apparatuses shall be fitted.
J. Compressors J 100 General 101 Compressors shall be certified. (Ref. DNV Rules for Classification of Ships Pt.4 Ch.5 Sec.4) 102 Compressors shall be equipped with all the accessories and instrumentation which are necessary for effective and dependable operation. 103 Compressors shall be designed for the gas types, pressure rating and delivery rates as specified by the operation and so designed that the gas is protected against contamination by lubricants. 104 The content of contaminants in delivered air from compressors shall not exceed acceptance criteria given in EN 12021 or equivalent standard. 105 Suitable protection shall be provided around moving parts, and the Safety Relief Valves shall exhaust to a safe place.
K. Umbilicals K 100 General 101 Umbilicals shall be designed, tested and certified in accordance with relevant sections of the most recent edition of ISO 13628-5 “Petroleum and natural gas industries – Design and operation of subsea production systems – Part 5: Subsea control umbilicals”. The relevant sections of the standard shall be agreed in a compliance matrix when the signed request for certification of the umbilicals is received by DNV. K 200 Hoses 201 Hoses for umbilicals shall comply with the requirements given in F. Hoses intended for operation with a larger external pressure than the internal pressure, shall be able to withstand 1.5 times this pressure difference without collapsing or shall be able to collapse without signs of permanent deformation. K 300 Electrical cables 301 Electrical cables for umbilicals shall comply with requirements given for umbilicals in Sec.5. 302 The minimum average thickness of insulating walls and temperature classes shall be in accordance with DNV Rules for Classification of Ships Pt.4 Ch.8. K 400 Sheathing 401 Any sheathing of a compact umbilical shall be of a design which avoids build-up of an inside gas pressure in the event of a small leakage from a hose. K 500 Strength members 501 The strength members of umbilicals shall have sufficient stiffness to avoid plastic yielding of electrical conductors at design load, and shall be properly secured.
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SECTION 5 ELECTRICAL SYSTEMS
A. Introduction A 100 Objectives 101 The objectives of this section are to emphasise the special needs associated with the design and manufacture of SURFACE diving systems. General requirements for electrical systems and components are given in DNV Rules for Classification of Ships Pt.4 Ch.8. A 200 Scope 201 DNV Rules for Classification of Ships Pt.4 Ch.8 and special needs associated with the design and manufacture of diving systems. 202 The key issues are identified in: a) the service definitions by defining “essential”, “emergency” and “non-important” services in Sec.2 D b) the power supply systems and capacity by specifications for emergency supply c) cables and penetrators d) documentation requirements 203 Material specification is included for insulation of cables in the inner area. 204 Design criteria for electrical penetrators are outlined. Philosophy on earthing is specified, in that hull return is not allowed. A 300 Application 301 This section applies to all SURFACE diving systems. 302 This section bears impact on Sec.2 (location of SURFACE diving system in hazardous zones), Sec.4, Sec.6, Sec.7, Sec.8 and Sec.9. A 400 References 401 Recognised production standards include those provided by the International Electro technical Commission (IEC). 402 The following codes and standards are applicable: a) DNV Rules for Classification of Ships Pt.4 Ch.8 b) Relevant IEC equipment construction and design standards referred to c) IMCA “Code of practice for the safe use of electricity underwater” d) DNV Standard DNV-OS-D201 “Electrical Installations” - Informative A 500 Procedural requirements, approval and certification 501 Procedural requirements, Approval and Certification requirements are given in DNV-DSS-105 Appendix A. A 600 Documentation 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. Further references with regards to general requirements are given in Sec.2 of this standard. 602 A system philosophy with general arrangement and where the equipment is placed shall be submitted early on in the project. 603 Single line distribution system diagrams for the whole installation. The diagrams shall give information on full load, cable types and cross sections, and make, type and rating of fuse- and switchgear for all distribution circuits. 604 Calculations on load balance, including emergency consumption and battery capacities. 605 Complete multi-wire diagrams, preferably key diagrams, of control and alarm circuits for all motors or other consumers. 606 A list of ALARMS and Monitoring Parameters shall be submitted for information. 607 Plans showing arrangements of batteries with information about their make, type and capacity. 608 Plans showing arrangement and single line diagrams of the communication system.
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609 Complete list of components and documentation on any tests carried out on all electrical equipment to be permanently installed within the chamber - and the wet-bell (if applicable). A 700 Survey and testing requirements during and after manufacture 701 In addition to the test requirements given here, detailed requirements are found in DNV-RP-E401. 702 A test for insulation resistance shall be applied to every circuit between all insulated poles and earth, and between individual insulated poles. A minimum value of 1 megaohm shall be attainable. 703 Main and emergency power supplies shall be tested. 704 Electrical penetrators shall be tested at the manufacturers as specified below. Tests shall be made between each conductor and screen and tests shall be carried out on penetrators from the same production batch. The tests shall be carried out in the sequence they are listed. The penetrators shall show no sign of deficiency during and after the testing. 705 Tests to be carried out include: a) a voltage test, by applying 1 kV plus twice the design voltage for 1 minute between each conductor and screen separately b) a hydrostatic test to a pressure of twice the design pressure, repeated 5 times c) a gas leakage test with the cables cut and open with air to twice the design pressure d) an insulation test to 5 Megaohms at the design pressure, applying saltwater A 800 Survey and testing requirements during and after assembly 801 Survey and testing during and after assembly shall be carried out according to an approved inspection and test procedure proposed by the builder in compliance with applicable requirements in DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.10D. Inspection and Testing. A 900 Survey and testing requirements during and after installation 901 Survey and testing during and after installation shall be carried out according to an approved inspection and test procedure proposed by the builder in compliance with applicable requirements in DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.10D. Inspection and Testing. 902 During the sea trials the normal launch and recovery system will be tested to the maximum depth. For SURFACE diving systems employing a “wet-bell” the electrical systems shall be checked for proper function. A 1000 Markings and signboards 1001 Markings and signboards according to DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.3E A 1100 Materials 1101 Materials shall comply with DNV Rules for Classification of Ships Pt.4 Ch.8.
B. System Design B 100 Design principles 101 The electrical systems and installations supplying Essential, Emergency and Normal services related to the divers and or the diving operation, shall meet the requirements for such services as defined in Sec.2 E, 102 Electrical circuits and equipment used in water shall be considered in each separate case and in accordance with IMCA D 045, R015 “Code of practice for the safe use of electricity underwater”. Provisions shall be made to reduce the possible fault currents, to which a diver can be exposed, to a harmless level. 103 The location of rechargeable battery installations are considered a hazardous area and shall be carefully considered during the conceptual design of the diving system lay-out early in the project, in compliance with DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.2 I400. B 200 System voltages 201 For installations within the inner area (see definitions under Sec.1D), the following maximum system voltages are permitted: a) The chamber: i) For power and heating equipment: max. 250 V A.C. if protected against accidental touching or insulation failures and fitted with a trip device. ii) For lighting, socket outlets, portable appliances and other consumers supplied by flexible cables and for communication and instrumentation equipment: max. 30 V D.C. These systems shall be supplied by isolating transformers.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.5 – Page 50 b) The wet-bell (when applicable): i) For all electrical equipment, voltages will be accepted up to max 30 V D.C., and shall be supplied by isolating transformers. ii) Higher voltages than specified above may be acceptable upon special consideration, provided additional precautions are taken in order to obtain an equivalent safety standard, e.g.: by use of earth fault circuit breakers. B 300 Main electric power supply system The electrical systems and installations supplying essential services related to the divers and or the diving operation as defined in Sec.2 D, shall be supplied from a main and an emergency or transitional source of power as required by DNV-Rules for Classification of Ships Pt.4 Ch.8. B 400 System functionality and design 401 The distribution system shall be such that, the failure of any single component cannot influence or set other services out of function for longer periods. The capacity of the main source of power shall be able to provide power to all normal and essential services according to Sec.2E, and shall be included in the services to be supplied by the main source of power as described in DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.2B and interpreting SOLAS Ch. II-1/40.1.1. 402 The capacity of emergency source of power shall be able to provide power to all emergency services according to Sec.2E, and shall be included in the services to be supplied by the emergency source of power as described in DNV Rules for Classification of Ships Pt.4 Ch.8 Sec2C and interpreting SOLAS Ch. II-1/43.2. 403 The emergency source of power and the emergency power distribution shall be capable of handling peak loads. 404 Power supplies required for the operation of life support systems and other essential services shall be sufficient for the life-support duration in order to cater for safe termination of the diving operation. 405 Each compression chamber shall be provided with a main and emergency source of lighting sufficient for the life-support time and of sufficient luminosity to allow the occupants to read gauges and operate essential systems within the chamber. Ingress of adequate light through the windows may be accepted as emergency lighting when appropriate. B 500 Emergency power supply system 501 In the event of failure of the main source of electrical power supply to the diving system an independent source of electrical power should be available for the safe termination of the diving operation. It is admissible to use the ship's emergency source of electrical power as an emergency source of electrical power if it has sufficient electrical power capacity to supply the diving system and the emergency load for the vessel at the same time. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.10.2) 502 The alternative source of electrical power should be located outside the machinery casings to ensure its functioning in the event of fire or other casualty causing failure to the main electrical installation. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.10.3) 503 The diving system shall have a source of emergency power and an emergency power supply system independent of the main source of power and the main power supply system, as required by DNV Rules for Classification of Ships Pt.4 Ch.8 that outlines the SOLAS II-1 Part D Regulation 43 requirements. 504 The emergency source of power shall be a self-contained, independent source of power. It shall immediately supply at least those services specified as emergency consumers in Sec.2 D and shall be either: a) a generator, driven by a suitable prime mover, or b) an accumulator battery, or c) the ship's emergency switchboard, or d) a combination of the above 505 Where this source of power is a generator, it shall be started automatically upon failure of the electrical supply from the main source and shall be automatically connected within 45 sec., thereby providing emergency services. 506 Where this source of power is an accumulator battery, it shall be automatically connected to an emergency power supply system in the event of failure of the main source of electrical power. It shall be capable of carrying the maximum emergency load for a time specified under Sec.2E without excessive voltage drop, carrying the emergency electrical load without recharging while maintaining the voltage of the battery throughout the discharge period within 12% above or below its nominal voltage.
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B 600 Transitional source 601 The following consumers shall be provided with transitional power (Uninterrupted Power Supplies): a) condition monitoring of emergency batteries b) emergency lighting, including external strobe lighting on basket/wet-bell c) emergency communication d) alarm systems for the emergency services 602 If other emergency consumers must be available in the switchover period from main to emergency power, either for operational reasons or to avoid malfunction of the service, a transitional power source (battery backup) for these consumers shall be provided. The capacity of this transitional power shall be minimum 30 minutes. (See SOLAS II-1 Part D Regulation 43 para.4.) B 700 Battery systems 701 Batteries shall not normally be installed within the inner areas in the chambers. 702 Battery housings shall be provided with adequate and unobstructed ventilation to open air in accordance with DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.2 I400, so that an accumulation of generated flammable gases is avoided. The ventilation intake shall be fed into the lower parts and the outlet arranged in the uppermost part of the housing. B 800 Electric power distribution 801 All switchboards shall be designed, constructed, tested and certified in accordance with the requirements given in DNV Rules for Classification of Ships Pt.4 Ch.8. 802 If the main power to the diving system is supplied from a distribution board, this board shall have two independent supply circuits from different sections of the main switchboard or separate power supplies. 803 Control gear in the inner area shall normally not be fitted. However, special arrangement may be acceptable after consideration in each case, based on special precautions. 804 Devices for easy disconnection of all electrical installations in the decompression chambers in an emergency situation shall be fitted. These devices shall be located on the control stand. It shall be possible to disconnect each chamber separately. 805 Emergency circuits wiring is considered to be an essential component in the diving system and shall therefore be fire proofed in accordance with the requirements in Sec.2 E800 when supplies are sourced from outside the outer area. Guidance note: Allowances are given to IEC 60331 cables protected by A0 division trays or piping.
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B 900 Lighting 901 Each surface compression chamber and diving bell should have adequate means of normal and emergency lighting to allow an occupant to read gauges and operate the system within each compartment. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.10.4) B 1000 Vessel arrangement 1001 Requirements for system placement and arrangement are given in Sec.2 F.
C. Equipment in general C 100 General requirements 101 All electrical equipment and assemblies shall be designed and arranged in order to minimise the risk of fire, explosion, electrical shock, emission of toxic gases to personnel, and galvanic action of the surface compression chamber or wet-bell. 102 The electric power supply arrangement shall be designed to minimise the risk of electrical capacity depletion as a result of a fault.
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C 200 Environmental requirements 201 All electrical equipment and installation, including power supply arrangements, should be designed for the environment in which they will operate to minimize the risk of fire, explosion, electrical shock and emission of toxic gases to personnel, and galvanic action of the surface compression chamber or diving bell. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.10.1) 202 The electrical equipment and installations, including power supply arrangements, shall be constructed and installed to operate satisfactorily under all environmental conditions for which the diving system is designed. Reference is given to DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.2. 203 Electrical equipment within the compression chamber shall be designed for hyperbaric use, oxygen- enriched atmospheres, high humidity levels and marine application. Reference is made to: a) DNV Rules for Classification of Ships Pt.4 Ch.8 b) NFPA53M (National Fire Protection Agency) “Manual on Fire Hazards in Oxygen-Enriched Atmospheres 1990”, c) IMCA D 045 “Code of practice for the safe use of electricity underwater”, and d) IMCA D 041 “Use of battery operated equipment in hyperbaric conditions”. 204 All materials of submerged systems shall be such that their electrical and mechanical properties are not influenced by water absorption. C 300 Termination and cable penetrations 301 All electrical penetrators in pressure containing structures shall be purpose designed, certified and shall be arranged with separate fittings. 302 Penetrators in pressure vessels shall be gas and water-tight even in the event of damage to the connecting cables. C 400 Earthing 401 Electrical systems with hull return shall not be applied. Electrical distribution systems shall have insulated neutral (IT). 402 All pressure vessels for human occupancy (PVHOs) shall be provided with earthing connection devices for external main protective earth bonding. 403 In the water, all metal enclosures shall be earthed by means of a copper earth conductor incorporated in the supply cable, with cross-section at least of the same size as the supply conductors and not less than 1 mm2. For cables having metal wire braid or armour this may alternatively be used as earth conductor, provided that the braiding cross section is sufficient. C 500 Insulation 501 Each insulated supply system, including the secondary side of step-down or isolating transformers (or converters) shall be provided with an automatic insulation monitoring device, actuating switch-off and alarm by insulation faults. Alarm only may be used if a sudden switch-off of the equipment may cause danger for the divers. This insulation monitoring shall be continuous. 502 The indicator shall be located at the control stand. Guidance note: Protection against insulation failures may be achieved by double insulated apparatus or earth fault circuit breakers.
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D. Miscellaneous Equipment D 100 General 101 Electric motors placed in the inner area shall be provided with overload alarms or be inherently safe. The alarms may be initiated by over current, or by temperature detector in the motor itself. The normal over current protections (short circuit protection) on the motors shall also be in place. Guidance note: The requirement provides safety against overheating, with the possible development of toxic gasses, and or danger of flash fire in oxygen enriched environments. In special cases there may be other risks involved in overheating of the motors. However, if the motor is considered inherently safe, the requirement for the overload alarms may be revoked. This is considered preferable in cases where the number of alarms should be kept at a minimum so as to avoid stressful operating conditions and or confusion.
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102 Pressure resistant enclosures in the inner area or on the wet-bell shall be designed for 1.3 times the design pressure of the diving system. Tests shall be carried out with gas or water as applicable. D 200 Lighting equipment – inner area 201 Protection against possible bursting of electrical bulbs shall be in place.
E. Cables E 100 Application 101 Cables for use in the outer area shall comply with DNV Rules for Classification of Ships Pt.4 Ch.8. All cables shall have an earthed braiding or screen around the conductors and be equipped with an insulating outer sheet. 102 Cables for use in the inner area shall comply with the requirements in 101 above, with exception to the materials used. The materials shall be designed for the purpose of being installed into a hyperbaric atmosphere. The cables in the inner area shall be halogen free and shall not give off toxic, noxious or flammable gases even when overheated. Dismantled ends of insulated conductors shall be protected with sleeves of a non- combustible material (e.g. glass fibre weave). Ordinary ship cables with insulation of a halogenated material (e.g. P.V.C.) shall not be accepted. Synthetic insulation materials based on P.T.F.E. (Polytetrafluoroethylene) may be accepted. 103 Flexible cables for transmission of electrical power and signals from the surface support to the divers in the water and the wet-bell shall be constructed as “dry-core cable” (i.e. water shall not reach the insulation of the individual conductors). 104 The submerged cables shall be able to withstand an external hydrostatic pressure of 1.3 times the actual external pressure. 105 Unless installed in pipes, electrical cables shall be readily accessible for visual inspection. 106 Tensile loads shall not be transferred to the electrical cables.
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SECTION 6 FIRE PREVENTION, DETECTION AND EXTINCTION
A. Introduction A 100 Objective 101 The objectives of this section are to specify additional requirements for fire protection serving SURFACE diving systems. General requirements for fire protection are given in DNV Rules for Classification of Ships Pt.4 Ch.10. A 200 Scope 201 Compliance with DNV Rules for Classification of Ships Pt.4 Ch.10. Issues relating to installation on- board a support vessel are given in Sec.2F 202 Key issues are identified through requirements for materials, insulation and separation from adjacent spaces, sprinkler systems and extinction agents. Reductions of hazards are ensured through these issues. A 300 Application 301 These requirements apply to all DSV-SURFACE systems. However, some systems may be located on open deck. In these cases the requirements for insulation against adjacent spaces and requirements for sprinkler systems may be more lenient. 302 This section bears impact on Sec.5 (build-up of static electricity, degree of protection provided by enclosure IP for equipment on chambers covered by sprinkler systems, power to alarms) and Sec.9. A 400 References 401 For quantitative design parameters and functional requirements, reference is made to the relevant standards and guidelines, including DNV Rules for Classification of Ships Pt.4 Ch.10. 402 In addition supplementary information is found in the National Fire Protection Agency Codes' chapters on hyperbaric systems and oxygen enriched environments. 403 Requirements applicable to the support vessel are given in SOLAS. 404 Further references are given to: a) DNV Rules for Classification of Ships Pt.5 Ch.16 b) IMO res. MSC.61(67) (FTP Code) c) DNV Standard OS-A101 “Safety Principles and Arrangements” Sec.4. d) IMO Res. MSC/Circ.848 MSC.98(73) (FSS Code) A 500 Procedural requirements, approval and certification 501 Procedural requirements, Approval and Certification requirements are given in DNV-DSS-105 Appendix A. A 600 Documentation requirements 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. Further references with regards to general requirements are given in Sec.2 of this standard. 602 Fire prevention, detection and extinction shall be documented as follows: a) A List of all materials to be installed in the inner area, where possible with data on and or evaluation of flammability in conditions under which the materials can be used. b) Plans and specifications of fire detection, fire alarm and fire extinction equipment for both the inner and outer area. A 700 Survey and testing requirements during and after manufacture 701 In addition to the test requirements given here, detailed requirements are found in DNV-RP-E401. A 800 Survey and testing requirements during and after assembly 801 The fire detection, fire alarm and fire extinction systems in the inner areas shall be tested for proper function according to specifications. A 900 Survey and testing requirements during and after installation 901 For requirements relating to installation of diving systems, refer to Sec.2 and DNV Rules for Classification of Ships Pt.5 Ch.16.
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902 Structural fire protection shall be documented and surveyed visually. 903 The fire detection, fire alarm and fire extinction systems in the outer areas shall be tested for proper function according to specifications. A 1000 Markings and signboards 1001 Markings and signboards shall be posted according to the relevant requirements. A 1100 Materials 1101 All materials and equipment used in connection with the diving system should be, as far as is reasonably practicable, of fire-retardant type in order to minimize the risk of fire and sources of ignition. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.9.1) 1102 The use of combustible materials shall be avoided wherever possible. Combustible materials include materials which may be brought to explode, or burn independently in the resulting gas environment, applicable to the outer area air at a pressure of 1 bar or the inner area at applicable gas mixtures and maximum pressure. 1103 Structural components, furniture and knobs, paints, varnishes and adhesives applied to these, shall be of non-hazardous materials., i.e. they shall be tested in accordance with relevant parts of IMO res. MSC.61(67) (FTP Code) or other acknowledged standard. Guidance note: In order to comply with 602, materials for use in inner area should be tested at an elevated pressure. Where such materials are not available, fitting a fixed fire extinguishing system in the inner area may be considered as an alternative.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 1104 Materials and arrangements shall, wherever possible, be made so as to avoid build-up of static electricity and to minimise the rise of spark production due to electrical failures or combination of materials. In inner areas without electrical equipment, the furniture and floors of electrically conductor materials may be used. For inner areas where electrical equipment is used, the materials and arrangements shall be made so as to minimise faulty contact with earthed metalwork.
B. Fire Protection B 100 Arrangement 101 When applicable, Control rooms for SURFACE diving systems located in hazardous zone 2 shall comply with the requirements given in DNV Standard OS-A101 “Safety Principles and Arrangements” Sec.4. Other control stands, essential to the function of the diving system, shall be protected such that the controls may be maintained whilst the divers are being evacuated in the event of a fire. 102 SURFACE diving systems shall have structural fire protection according to the requirements given in Sec.2 E800 and Sec.2 F500. 103 Liquid fuel burning machines shall be fitted with either alarms or shut-off valves to ensure that day-tanks, if fitted, cannot be filled to overflow. 104 Oxygen dumped from the diving system shall be ducted for dumping at a safe place.
C. Fire Detection and Alarm System C 100 “Outer area” 101 Interior spaces containing diving equipment such as surface compression chambers, diving bells, gas storage, compressors and control stands should be covered with an automatic fire detection and alarm system and a suitable fixed fire-extinguishing system. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.9.3) 102 When situated in enclosed spaces the “outer area” shall be equipped with automatic fire detection and alarm system complying with DNV Rules for Classification of Ships Pt.4 Ch.10. The section or loop of detectors covering the “outer area” shall not cover other spaces. C 200 “Inner area” 201 The “inner area” shall be equipped with automatic fire detection and alarm system complying with DNV Rules for Classification of Ships Pt.4 Ch.10. The section or loop of detectors covering the “inner area” shall not cover other spaces.
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C 300 Fault detection 301 Provisions shall be made for warning of faults; e.g., voltage failure, broken line, earth fault, etc., in the fire alarm and detection system.
D. Fire Extinguishing D 100 “Outer area” 101 When situated in enclosed spaces, the “outer area” shall be equipped with a fixed, manually actuated fire extinguishing system with such a layout as to cover the complete system. 102 The extinguishing system shall be either: a) a pressure water spraying system approved for use in machinery spaces of cat.A, or b) a gas system approved for use in machinery spaces of cat. A 103 If a gas system is selected, the agent shall be of a type not hazardous to humans in the concentration foreseeable in the protected space. The concentration shall be below the NOAEL as defined in IMO MSC/ Circ.848 as amended. 104 When pressure vessels are situated in enclosed spaces, a manually actuated water spray system having an application rate of 10 l/m2/per minute of the horizontal projected area should be provided to cool and protect such pressure vessels in the event of external fire. When pressure vessels are situated on open decks, fire hoses may be considered as providing the necessary protection. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.9.5) 105 If water supply for object protection of pressure vessels and water-based fixed fire extinguishing systems are connected to the mother-vessel’s fire pumps, both pressure and capacity (required application rate) shall be confirmed. In addition to required capacity for the diving system, the mother-vessel’s fire pumps shall in addition be capable of delivering two jets of water supplied trough 52 mm dia. fire hoses with 19 mm nozzles. 106 When situated on open deck, the outer area shall be provided with fire extinguishing equipment, which shall be considered in each case. D 200 “Inner area” 201 Each compartment in a surface compression chamber should have a suitable means of extinguishing a fire in the interior which would provide rapid and efficient distribution of the extinguishing agent to any part of the chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.9.6) 202 The “inner area” shall be equipped with a fixed, manually actuated fire extinguishing system with such a layout as to cover the compartments. It shall be possible to actuate the extinguisher both from within the compartments and from outside. 203 The extinguishing agent for the “inner area” shall be rechargeable without depressurising, and provisions shall be made for possible discharge of less than the total supply of extinguishing agent 204 The extinguishing agent shall be water, unless an approved alternative exists. 205 Fixed water-mist systems for inner area shall have minimum capacity of 2 shots of 2 min. duration with the required application rate. Response time upon activation shall follow NFPA99, maximum 3 sec.
E. Miscellaneous Equipment E 100 Breathing apparatus and fire-fighter's outfit 101 Breathing apparatus are required for control stations manned during recovery of the divers. 102 It shall be possible to carry out work and to communicate effectively in the control room even if there is no normal breathable atmosphere in the room. Release of dangerous quantities or mixtures of gas from chamber or gas plant shall never take place in the control room. 103 A complete set of fire-fighter's outfit complying with DNV Rules for Classification of Ships Pt.4 Ch.10/ FSS Code Ch.3.2 for each person required for operation of the diving system during a fire should be provided in a location close to the main control stands. The sets may be included in the other sets on-board but shall be additional to those required by SOLAS Reg. II-2/10.10.
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Guidance note: Fire-fighter's outfit is recommended in consideration of the time it may take for recovery of the divers from the water. The operator(s) of the diving system may be exposed to hot environments which render evacuation impossible unless they are protected whilst performing their work.
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E 200 Portable fire extinguishers 201 Portable fire extinguishers of approved types and designs should be distributed throughout the space containing the diving system. One of the portable fire-extinguishers should be stowed near the entrance to that space. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.9.4) 202 Portable fire extinguishers shall be of approved type and comply with FSS Code Ch.4. For “inner area” hyperbaric extinguishers shall be of approved type, containing non-toxic medium and certified for the maximum depth rating of the chamber in which they are placed. 203 Portable fire extinguishers shall be distributed throughout the space containing the diving system so that no point in the space is more than 10 m walking distance from an extinguisher. 204 One of the portable fire extinguishers shall be fitted near each entrance. 205 A portable fire extinguisher shall be fitted at the control stand. 206 Spare charges or extinguishers shall be provided on-board - 100% for the first 10, and 50% for remaining extinguishers. 207 The same type of portable extinguisher shall be used throughout the system. Compatibility with the remaining extinguishers, used elsewhere on the vessel, is recommended for extinguishers used in the outer area.
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SECTION 7 LAUNCH AND RECOVERY SYSTEMS (LARS)
A. Introduction A 100 Objectives 101 The objectives of this section are to specify additional requirements for lifting appliances serving SURFACE diving systems. General requirements for lifting appliances are given in DNV Standard for Certification No. 2.22 Lifting Appliances (Sec.9), incorporating specific requirements for lifting of personnel. A 200 Scope 201 Launch and recovery systems shall be certified compliant with statutory requirements applicable to the Flag State where the support vessel is registered, geographic area of operation and terms of delivery. 202 Key issues are identified through requirements for alternative recovery of divers. 203 Limitations are given in the rating of the launch and recovery systems with respect to a given, specified, sea-state. 204 Load conditions may need to be estimated through the use of calculations such as DNV-DS-E402 (Note: under development, meanwhile use DNV-OS-E402) Appendix A or equivalent. 205 Requirements for testing are given in A700. A 300 Application 301 These requirements apply to all SURFACE diving systems. 302 This section applies to all launch and recovery systems. However, requirements for launch and recovery of diver’s baskets may be more lenient with respect to emergency recovery, if it is possible for the surface supplied divers to ascend independent of the diver’s basket. 303 This section has impact on the requirements for strength with respect to deck loading on the support vessel and to the services from the support vessel. A 400 References 401 For quantitative design parameters and functional requirements, reference is made to relevant standards and guidelines, including DNV Standard for Certification No. 2.22 Lifting Appliances. 402 Further references are given to: a) DNV-DS-E402 (Note: under development, meanwhile use DNV-OS-E402) Appendix A or equivalent b) DNV Rules for Classification of Ships Pt.5 Ch.16 c) ILO Convention No. 152 A 500 Procedural requirements, approval and certification 501 Procedural requirements, Approval and Certification requirements are given in DNV-DSS-105 Appendix A. 502 Launch and recovery systems shall normally be certified by a competent person as lifting appliances in accordance with the procedures applicable for the system and compliant with ILO Convention No. 152. Operational limitations shall be stated in an appendix to the certificate. For DNV Classed diving systems a CG2 certificate will be issued by DNV for the LARS. A 600 Documentation 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. Further references with regards to general requirements are given in Sec.2 of this standard. 602 Launch and recovery systems shall be documented as a lifting appliance in accordance with DNV Standard for Certification No. 2.22 Lifting Appliances. In addition, plans and supplementary documentation shall be made available as follows: a) Plans showing the arrangement of the launch and recovery system with specifications of loads, and dimensions of strength members. b) Plans showing the function of the systems, and giving particulars of the systems. The plans shall show a schematic arrangement of the hydraulic or pneumatic piping systems and specification of controls and power supply. c) Calculation of the design load according to C100.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.7 – Page 59 d) Calculation of necessary design load for umbilical and guide ropes. e) Plans and specification of structural parts, ropes, sockets, blocks, sheaves, winches, and emergency ascent arrangement for the basket or wet-bell. f) Specifications of materials and welds, and extent of non-destructive testing. g) Specifications of wire ropes and their end connections. h) Specification of safety devices (limit switches, automatic stop of operating handle, automatic locking of winch in case of power failure, etc.). i) Plans and specifications for systems used for emergency ascent of the divers and retrieval of the basket or wet-bell. j) Information on specification of working weight, displacement and stability of the basket or wet-bell, with all hydrostatic properties accounted for. A 700 Survey and testing requirements during and after manufacture 701 In addition to the test requirements given here, detailed requirements are found in DNV Standard for Certification No. 2.22 Lifting Appliances and DNV-RP-E401. A 800 Survey and testing requirements during and after assembly 801 Basket/Wet-bell a) The working weight shall be ascertained b) The stability in normal and emergency modes shall be tested 802 Launch and recovery systems shall be subjected to tests for structural strength and for function and power. 803 A static load test to a load equal to the design load shall be carried out. 804 Functional and power testing of normal and emergency systems shall be carried out with a functional test load of 1.25 times the working weight in the most unfavourable position. It shall be demonstrated that the systems are capable of carrying out all motions in a safe and smooth manner. 805 Monitoring of functional parameters during the tests, e.g. pressure peaks in hydraulic systems may be required. A 900 Survey and testing requirements during and after installation 901 During the sea trials the normal launch and recovery system shall be tested with the working weight of the basket or wet-bell to the maximum depth. 902 A recovery test of the basket or wet-bell shall be carried out simulating emergency operations conditions. A 1000 Marking and signposts 1001 The launch and recovery system shall, in an easily visible place, be fitted with a nameplate giving the following particulars: a) identification number b) static test load c) functional test load d) working weight e) surveyor's mark and identification 1002 The above loads shall be specified for each subsystem involved. A 1100 Materials 1101 Materials shall be compliant with the requirements given in DNV Standard for Certification No. 2.22 Lifting Appliances.
B. Design Principles B 100 General 101 Where the following IMO requirements refer to “bell” they shall also apply to divers’ baskets in the context of this standard. 102 A diving system should be equipped with a main handling system to ensure safe transportation of the diving bell between the work location and the surface compression chamber. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.1)
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103 Connection of the main lift wire to basket (or wet bell) shall have two retaining means for the removable pin. 104 For diving operations where there are no hull obstructions near the diving site, and the freeboard is less than 2 metres, one of the following options shall be utilised: a) wet bell or diving basket(s) including equipment for the deployment of a surface standby diver b) ladder which extends at least 2 metres below the surface in calm water. The ladder shall have sufficient holds under and above water and on deck level to allow the diver to step easily onto the deck. In addition a dedicated arrangement e.g. a crane, A-frame or davit, certified for lifting of personnel, with sufficient reach shall be present to recover an incapacitated diver from the water by a safety harness onto the deck 105 For diving operations where there are obstructions at the diving site, and/or a freeboard of more than 2 metres, one of the following options shall be utilised: a) wet bell including equipment for the deployment of a surface standby diver b) two diving baskets – one for the diver(s) and one for the standby diver B 200 Divers basket and wet-bell (when installed) 201 A diving bell should: .1 be provided with adequate protection against mechanical damage during handling operation .2 be equipped with one extra lifting point designed to take the entire dry weight of the bell including ballast and equipment as well as the weight of the divers staying on in the bell. .3 be equipped with means whereby each diver using the bell is able to enter and leave it safely as well as with means for taking an unconscious diver up into a dry bell. .4 (Omitted text not applicable for SURFACE diving). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.3.1) Guidance note: The above IMO requirements for bells shall also apply to divers’ baskets in this case. Note that the design and location of the extra lifting fastening needs to be considered in view of the need to bring a basket or wet-bell close to the surface decompression chamber.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 202 Internally there shall be an attachment for lifting of divers into the wet-bell or basket, if assisted recovery is required in the particular design. 203 Each diving bell should have view ports that as far as practicable allow an occupant to observe divers outside the bell. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.3.4) The canopy of wet bells, if employed, shall be provided with windows that as far as practicable allow the occupants to observe diving and lifting operations outside the wet-bell. B 300 Function 301 The handling system should enable smooth and easily controllable handling of the diving bell. (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.7.3) The normal launch and recovery system shall be designed for a safe, smooth and easily controllable transportation of the divers in the design sea-state. 302 The lowering of diving bells under normal conditions should not be controlled by brakes, but by the drive system of the winches. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.4) 303 If the energy supply to the handling system fails, brakes should be engaged automatically. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.5) Manoeuvring systems shall be arranged for automatic stop when the operating handle is not operated (dead man’s handle). 304 Hoisting systems shall be fitted with a mechanical brake, which shall be engaged automatically when the hoisting motor stops. In the event of failure of the automatic brake a secondary means shall be provided to prevent the load from falling. This may be manual in operation and should be simple in design. 305 The launch and recovery system shall be designed so that the systems are locked in place if the energy supply fails or is switched off. 306 If the hoisting rope can enter the drum with an angle exceeding 2° from the right angle to the drum axis (the “fleet angle”), a spooling arrangement shall be fitted. The rope launch and recovery system shall not permit ropes to squeeze in between, or introduce permanent deformation to ropes in underlying layers on the drum. 307 The hoisting system shall be equipped with a “line-out” device showing the amount of wire that is spooled off the drum and a device which stops the basket or wet-bell at its lowermost and uppermost positions.
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Guidance note: Line-out monitoring is also needed when diving in certain adverse conditions, such as zero visibility. In such conditions it will be necessary to monitor line-out in order to safely carry out surface diving operations. When the diver is out of the stage, it should be possible to match the diver’s depth with the depth of the stage.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 308 Travelling cranes and trolleys shall be equipped with mechanical stops at their end positions. The system shall be equipped with limit switches preventing the launch and recovery of the wet-bell or basket outside of the launch and recovery area. A-frames shall be arranged with stops to prevent luffing-out beyond the maximum design angle. 309 Precautions shall be taken to avoid exceeding the design load in any part of the launch and recovery system including hoisting ropes and umbilical due to: a) large capacity of the power unit b) motions of the supporting vessel when the basket/wet-bell or weights are caught or held by suction to the sea floor c) failure on umbilical winch during launching of wet-bell 310 Structural members of the launch and recovery system might be subjected to forces imposed by separate units of a power system (e.g. A-frame tilted by hydraulic actuator on each leg.). The structural members are therefore either to be strong enough to sustain the resulting forces when one of the power units fails, or the power units shall be synchronised and an automatic alarm and stop system shall be activated when the synchronising is out of set limits. 311 Hydraulic power units shall be dedicated to the lifting appliance and not shared with other consumers, such as hydraulic driven tools. 312 Where direct visual monitoring of the winch drums from the winch control station is not practical, TV monitoring shall be fitted. 313 Primary and emergency lighting in all critical launch and recovery areas shall be provided. B 400 Recovery 401 In the event of single component failure of the main handling system, an alternative means should be provided whereby the bell can be returned to the surface compression chamber. In addition, provisions should be made for emergency retrieval of the bell if the main and alternative means fail. (-omitted, non-applicable text-). (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.6) There shall be at least one normal system (primary) and two (secondary and tertiary) mutually independent emergency means for recovery of the divers with return to the chambers. The alternative means shall comply with the same requirements for load strength as the main system if the basket/wet-bell is part of the recovery. 402 The two emergency means shall be arranged as follows: a) One emergency system (secondary) may be made for recovery by aid of the normal hoisting or guide rope(s). This system shall be independently powered from the normal system, and shall incorporate all transportation necessary to transport the divers to the surface chamber. b) One system (considered secondary) shall also provide an arrangement for stopping the basket or wet-bell from falling or descending, in the event of failure in the primary lifting wire. 403 Another emergency system, (tertiary), may be that the diving system is equipped with a separate launch and recovery system and a second basket or wet-bell. Provisions shall be available for recovery of the divers to the chambers. Alternatively this other emergency system (tertiary) may consist of an arrangement that permits the divers free ascend and shall incorporate all means necessary to transport the divers to the chamber. Where appropriate, the emergency recovery may incorporate a ladder if the freeboard and distance to the chamber allows for this. 404 The time taken to bring the diver(s) from 10 msw in the water until 10 msw equivalent in the chamber should not exceed 5 minutes in any of the three modes of recovery. 405 Guide wire equipment may, in addition to ensuring controlled movements of the basket or wet-bell in the water, function as a secondary means of recovery. B 500 Power 501 The hoisting power system shall be designed and tested to lift and manoeuvre a load of 1.25 times the working weight of the basket or wet-bell. This requirement is to ensure there is enough power to handle the basket or wet-bell under normal wave conditions.
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502 Handling systems and mating devices should enable easy and firm connection or disconnection of a diving bell (-omitted, non-applicable text-), even under conditions where the support ship or floating structure is rolling, pitching or listing to predetermined degrees. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.7) 503 The power of horizontal transportation systems shall be designed and tested for safe launch and recovery at list and trim as specified in C104 and Sec.2 E200. 504 The strength of the mechanical brake for the hoisting system shall be based on holding of the design load. After the static test, however, the brake may be adjusted to the working weight of the basket or wet-bell plus 40%. B 600 Umbilical 601 The length of the umbilicals, shall, as a minimum, allow an excursion of the basket or wet-bell to: a) dmax plus 5%, or b) actual bottom depth plus 5% 602 The termination points, where the umbilicals enter connectors and/or penetrators, shall not be subjected to significant loads or flexing. 603 The ultimate tensile strength of the umbilicals shall not be less than twice the maximum load expected during normal and emergency operations.
C. Strength C 100 Design loads 101 The handling system should be designed with adequate safety factors considering the environmental and operating conditions, including the dynamic loads which are encountered while handling the diving bell through the air-water interface. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.7.2) Reference is given to DNV Rules for Ships Pt.3 Ch.1 Sec.3 (Principles) & Sec.4. 102 The minimum design load shall be taken as 2.2 times the working weight of the basket or wet-bell. For exposed launching, typically over the side or stern of vessels, the design load shall be estimated as the largest most probable, resultant load over 24 hours in the operational design sea-state due to the following: a) working weight of basket or wet-bell and structural members of the launch and recovery system b) dynamical amplification due to list, trim and motion of the vessel c) roll angles up to +/- 22.5 degrees d) operation and response of the launch and recovery system e) hydrodynamic forces f) jerks in the hoisting ropes and impact on the system 103 The working weight of the basket or wet-bell shall be taken as the maximum weight of the fully equipped basket or wet-bell, including each fully equipped diver of 200 kg. The load from this weight applies to: a) launch and recovery in air, and b) launch and recovery submerged, combining the maximum negative buoyancy of the wire rope, umbilical and basket or wet-bell at maximum operating depth 104 In locked positions on a vessel, the launch and recovery system shall have a structural strength at least sufficient for the environmental conditions described in Sec.2. In addition to the motions and accelerations in the operational design sea-state, the minimum inclinations given in Table C1 shall be taken into account:
Table C1 Permanent inclinations Vessel type Permanent list Permanent trim Ship 5° 2° Semi-submersible 3° 3° 105 Dynamic loads due to start, stop, or a slack wire rope followed by a jerk, and hydrodynamic loads shall be estimated. Approximate estimates of expected dynamic loads during launch and recovery of diving basket or wet-bell and any connected cursor from a vessel which is stationary and heading in the main direction of incoming waves in the design sea-state are given in DNV-DS-E402 Appendix A (Note: currently under development, meanwhile use DNV-OS-E402).
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Guidance note: In the case of transferable systems, there will be a wide variety of potential support vessels and installation options. It stands to reason that these diving systems are delivered with a set design load and owners need to apply the DNV- OS-E402 Appendix A calculations to set the parameters for operating capability so that this may be entered into a certificate appendix for the particular installation. In practice the allowable operational loads may be regulated by load monitoring, as is done on modern diving systems. The Appendix A tool for estimating design loads, entered in a simple spread sheet, may be used to estimate sea states where the design load is given as a set value. The ship related variables can be altered when the estimation is carried out for a new installation on a different location.
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C 200 Dimensions 201 The minimum safety factor for steel wire ropes shall be 4 compared to Design Load defined in C100. Minimum safety factor for synthetic fibre wire ropes shall be 5 compared to Design Load defined in C100. Guidance note: Note that a SF of 4 times the minimum design load of 2.2 gives a SF of 8.8.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 202 Blocks, sheaves, shackles etc. shall comply with recognised national codes. Drums and pulley diameters shall correspond to the type of rope. For steel wire ropes this diameter shall not be taken less than specified by the rope manufacturer, and normally not less than 18 times the rope diameter. In the case of cross hauling, such equipment shall fulfil the same requirements for strength as the rest of the launch and recovery system. 203 Structural members shall be fabricated from certified materials and shall be designed with safety against: a) excessive yielding b) buckling c) fatigue fracture, and d) shall be in accordance with technical requirements in DNV Standard for Certification No. 2.22 Lifting Appliances, or equivalent accepted standards C 300 Foundations for launch and recovery systems and lifting appliances 301 Foundations for launch and recovery systems and lifting appliances shall be determined according to DNV Rules for Classification of Ships Pt.3 Ch.3 Sec.5 or according to other recognised standards. 302 The dynamic coefficient shall be taken as 2.2 or more when the lifting appliance is used for launch and recovery manned objects such as wet-bells, baskets or Hyperbaric Evacuation Systems. For other lifting appliances, not used for lifting people, the dynamic coefficient shall be 1.5 or more.
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SECTION 8 INSTRUMENTATION AND COMMUNICATION
A. Introduction A 100 Objective 101 The objectives of this section are to emphasise the special needs associated with the design and manufacture of diving systems. General requirements for instrumentation and communication systems and components are given in DNV Rules for Classification of Ships Pt.4 Ch.9. A 200 Scope 201 Recognised production standards include those provided by the International Electro technical Commission (IEC). 202 Material specification is included for insulation of cables in the inner area. A 300 Application 301 These requirements apply to all SURFACE diving systems. 302 This section bears impact on Sec.2 (location of SURFACE diving system in hazardous zones), Sec.4, Sec.6, Sec.7 and Sec.9. A 400 References 401 The following codes and standards are applicable: — DNV Rules for Classification of Ships Pt.4 Ch.9 — DNV Rules for Classification of Ships Pt.4 Ch.9 Sec.3 B 200 Electrical power distribution — DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.2 H 100 Control system — Relevant IEC equipment construction and design standards — DNV Standard DNV-OS-D202 “Instrumentation and Telecommunication systems” - Informative A 500 Procedural requirements, approval and certification 501 Procedural requirements, Approval and Certification requirements are given in DNV-DSS-105 Appendix A. A 600 Documentation 601 For installation of diving systems on-board or at a site, reference is given to DNV Rules for Classification of Ships Pt.5 Ch.16. Further references with regards to general requirements are given in Sec.2 of this standard. 602 The following document requirements assume a non-complex system. For complex instrumentation and/ or communication systems, scope shall be agreed on a case by case basis at the start of the project. 603 For instrumentation and communication systems the following shall be documented: a) Complete key diagrams, of control and alarm circuits for all motors or other consumers. b) Plans showing arrangements of batteries with information about their make, type and capacity. c) Plans showing arrangement and single line diagrams of the communication system. d) Complete list of components and documentation on any tests carried out on all equipment to be permanently installed within the chamber and the wet-bell. A 700 Survey and testing requirements during and after manufacture 701 In addition to the test requirements given here, detailed requirements are found in DNV-RP-E401. 702 The correct calibration of all essential instrumentation (compartment pressure gauges, gas analysis instruments etc.) shall be checked. A 800 Survey and testing requirements during and after assembly 801 Communication shall be tested after assembly, for proper function. 802 Control and monitoring system shall be tested according to an approved test procedure. A 900 Survey and testing requirements during and after installation 901 During the sea trials the normal launch and recovery system will be tested to the maximum depth. For SURFACE diving systems employing a “wet-bell” the communication system shall be tested.
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A 1000 Markings and signboards 1001 Markings and signboards shall be posted according to the relevant requirements in DNV Rules for Classification of Ships Pt.4 Ch.8 Sec.3 E. A 1100 Materials 1101 Equipment, including enclosures, shall meet the environmental requirements given in DNV Rules for Ships Pt.4 Ch.9 Sec.5.
B. Instrumentation B 100 General 101 A diving system should include the control equipment necessary for safe performance of diving operations. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.1.7) 102 In general, instrumentation shall comply with the relevant requirements in DNV Rules for Classification of Ships Pt.4 Ch.9. B 200 Power supply to control and monitoring systems 201 Power supply requirements for control and monitoring systems shall comply with the principles given in DNV Rules for Classification of Ships Pt.4 Ch.9. 202 Where instrumentation requires power supplies, this shall be designed on the basis of the system philosophy and redundancy philosophy as applicable. Requirements for essential, emergency and normal services are given in Sec.2 D. B 300 Monitoring and inspection during operation 301 Parameters that could jeopardise the safety of the divers, and or violate the integrity of a diving system, shall be monitored and evaluated with a frequency that enables remedial actions to be carried out before personal harm is done or the system is damaged. Guidance note: As a minimum the monitoring and inspection frequency should be such that the diving system, and consequently the SURFACE diving operation, shall not be endangered due to any realistic degradation or deterioration that may occur between two consecutive inspection intervals.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 302 Instrumentation may be required when visual inspection or simple measurements are not considered practical or reliable, and available design methods and previous experience are not sufficient for a reliable prediction of the performance of the system. 303 The various pressures in a diving system shall not exceed the design pressures of the components during normal steady-state operation. B 400 Pressure control system 401 A pressure control system is be used to prevent the internal pressures at any point in the diving system rising to excessive levels, or falling below prescribed levels. The pressure control system comprises the pressure regulating systems, pressure safety systems and associated instrumentation and alarm systems. 402 The purpose of the pressure regulating system is to maintain the operating pressures within acceptable limits during normal operation. The set pressures of the pressure regulating system shall be such that the local operational pressures are not exceeded at any point in the diving system. Due account shall be given to the tolerances of the pressure regulating system and the associated instrumentation. 403 The purpose of the pressure safety systems is to protect the systems during abnormal conditions, e.g. in the event of failure of the pressure regulating systems. The pressure safety systems shall operate automatically in accordance with the “fail safe” principles and with set pressures such that there is a low probability for: a) the internal pressure at any point in the diving system to exceed the design pressure (maximum operating pressure), and for b) the unintentional loss of pressure at any point in the diving system to fall below set values 404 The diving system may be divided into sections with different design pressures provided the pressure control system ensures that; for each section, the local operational pressure cannot be exceeded during normal operations and that the design pressure cannot be exceeded during abnormal operation. The pressure control shall also ensure that unwanted loss of pressure in one section does not occur as a result of an abnormal condition in another section.
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B 500 Control stands 501 With reference to requirements in Sec.4 and DNV Rules for Classification of Ships Pt.4 Ch.9 Sec.6, the design of control rooms shall consider ergonomics such as communication and a systematic arrangement of equipment, according to a documented traffic flow chart. Further, it should be ensured that noise or other disturbance when working does not occur. Control stands for diving operations shall therefore be separated from the control stations associated with the other operations on board. 502 The diving system should be so arranged as to ensure that centralized control of the safe operation of the system can be maintained under all weather conditions. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.11.1) 503 Indication and operation of all vital life support conditions to and from the divers, the chamber(s) and the wet-bell(s) shall be arranged at a single control stand. The control stand shall be equipped for easy operation and control of the diving system. There shall be schematic indication of gas flow lines. 504 A surface compression chamber should be equipped with such valves, gauges and other fittings as are necessary to control and indicate the internal pressure and safe environment of each compartment from outside the chamber at a centralized position. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.5.2)
Table B1 As a minimum, facilities should be provided at the central control position to monitor the values of the following parameters for each occupied compartment: Compartments Parameters Surface compression chamber Diving bell Pressure or depth *1 Yes Yes *2 Temperature *1 Yes Humidity Yes Oxygen partial pressure *1 Yes Yes CO2 partial pressure Yes Yes *1/ These parameters should be indicated continuously. *2/ Pressure or depth (omitted non-applicable text) outside bell should be indicated. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.11.2) 505 The control stands shall also have indicators showing continuously: — the pressure in the surface mounted gas containers connected — the pressure after all pressure reducers — the pressure in each chamber compartment — the pressure (depth) at each divers location — the pressure at the wet-bell (if employed) 506 Pressure indicators on the control stand for the divers, the wet-bell and chamber compartments shall be arranged for a possible comparison between each other or with a permanently installed master indicator. If cross-connections are incorporated, these shall be arranged in such a way as to give the operators an indication when cross-connection is being conducted. 507 Instrumentation for pressure measuring for the divers, the wet-bell and chamber compartments shall have an accuracy of +/-0.3% of full scale. In addition, to facilitate accurate decompression, pressure indicators for the chambers shall facilitate depth measurements with an accuracy of +/-0.25 msw. in the depth range from 30 msw. to 0. The accuracy of other instruments for pressure measuring shall be +/-1% of full scale. 508 The control stands shall also have a system for continuous indication of: a) oxygen content in each compartment individually b) oxygen content in the supply to the: i) umbilicals ii) compartments iii) masks in compartments 509 The monitoring systems shall be fitted with audible and visual high and low level alarm. 510 A list of the essential gauges in the system shall be posted at the control stand. 511 Permanent provisions for calibration of, and comparison and back-up between, oxygen analysing instruments shall be arranged on the control stand. 512 There shall be an audio-visual gas flow indicator in the oxygen supply to the chambers, when applicable. 513 The control stands shall have a system for regular indication of carbon dioxide content in each compartment individually.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 Sec.8 – Page 67
514 There shall be systems for indication of temperature and humidity in the inner area displayed at the control stand. 515 Alarms for abnormal conditions are required at the control stand, if automatic environmental control systems are arranged for regulation of gas composition, pressure and temperature in the inner area. B 600 Pressure indicators in wet-bell and chambers 601 Valves, gauges and other fittings should be provided outside the bell as necessary to control and indicate the pressure and safe environment within the diving bell.(omitted text) (IMO Code Of Safety For Diving Systems Chapter 2 Design, Construction and Survey 2.5.3) 602 A wet-bell shall contain local equipment to monitor important parameters in all situations, such as depth, pressure of gas supply from surface, pressure of on-board emergency gas supply 603 The chamber compartments shall be fitted with indicators visible to the divers inside, showing internal pressure. 604 Means shall be provided for isolating all pressure indicators without interrupting vital functions in the gas distribution system. If isolation is incorporated, these shall be arranged in such a way as to give the operators an indication when isolation is being conducted. B 700 Oxygen and carbon dioxide analysing systems in wet-bell and chambers 701 Provision should be made within the bell for an independent means of monitoring oxygen and carbon dioxide levels. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.11.3) In the case of diving in a wet-bell, this is only required when risk evaluation according to given locations and operations reveal a need for monitoring these parameters locally in the wet-bell. 702 Oxygen analysing systems shall have an accuracy of at least +/-0.015 bar partial pressure oxygen. 703 The chamber compartments shall have independent oxygen analysers inside. 704 Carbon dioxide analysing systems shall have an accuracy of +/-0.001 bar partial pressure. 705 Carbon dioxide gas mixture for calibration shall be available. B 800 Other gases 801 Where breathing gas is supplied directly from running compressors, a means of analysing the air for Carbon Monoxide shall be provided for continuous monitoring - incorporating audio/visual alarm. 802 The instrumentation for systems intended for other gases than air and oxygen mixes shall be considered in each case, including Hydrogen Sulphide.
803 Diving shall not take place if CO and/or H2S are present, and there shall be a system for shutting down intakes of air into the diving system in cases where these gases may be present. Guidance note: Operations in connection with exploration of oil may require instrumentation for the analysis of hydrocarbon gases and H2S.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 804 Calibration gases shall be available for each relevant gas mix. B 900 Automatic environmental control systems (if employed) 901 The following requirements apply when systems for automatic regulation of gas composition, pressure and temperature in the inner area are installed. 902 The design principles given in DNV Rules for Classification of Ships Pt.4 Ch.9, apply on a general basis. 903 The most probable failure in the systems shall result in the least critical of any possible new conditions (fail to safety). 904 Automatic control systems shall keep process variables within the limits specified during normal working conditions and the alarm systems shall be activated when the limits are exceeded. 905 Alarm at the control stand is required for abnormal conditions. The alarm system is also to be activated by failures in the alarm system circuitry. The alarm system shall be independent of the automatic control system so that failure in one of the systems cannot inhibit operation of the other system. 906 A manual back-up system for the automatic control system is required.
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C. Communication C 100 General 101 Communications systems shall comply with the relevant requirements given in DNV Rules for Classification of Ships Pt.5 Ch.16. C 200 Visual observation of divers 201 Visual observation of divers in each compartment shall be possible. C 300 Voice communication systems 301 Voice communication should be hard-wired, especially when critical operations are coordinated. 302 The communication system should be arranged for direct two-way communication between the control stand and: — diver in water — diving bell — each compartment of the chambers — diving system handling positions — dynamic positioning room — bridge, ship's command centre or drilling floor (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.12.1) 303 Communication systems shall be arranged for direct voice communication between the control stand and other control stations as needed. If a crane is employed during diving operations, there shall be direct communications with the crane operator. 304 Alternative means of communication with divers in the surface compression chamber and diving bell should be available in emergency. (IMO Code of Safety for Diving Systems Chapter 2 Design, Construction and Survey 2.12.2) 305 The control stand for the divers in the water shall be provided with equipment for audio-recording of all communications with the divers. 306 Special consideration applies when portable equipment is used for mandatory two way voice communication on-board. SOLAS V Reg.17 – EMC – applies regarding this use in the bridge. Guidance note: Mandatory two way voice communication equipment: DNV will accept UHF equipment without a valid DNV type approval certificate if the yard issues a Declaration saying that the same UHF systems are also installed on other vessels, so far have not received negative feedback from the owners, and that the yard agrees to take full responsibility for the UHF systems. This kind of acceptance is so-called “case by case” approval, meaning that DNV might not accept the systems in the future if new information comes to light that prevents such acceptance.
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SECTION 9 EVACUATION SYSTEMS
A. Introduction A 100 Objectives 101 The objective of this section is to inform that requirements for evacuation systems are regulated by the Maritime Administrations and/or shelf state authorities. A 200 Scope 201 The scope of work is according to instructions from the Maritime administration. A 300 Application 301 This section applies to all DSV-SURFACE systems where SOLAS requirements may be applied if practicably possible. These requirements may also be applicable as Flag State, or Shelf state, requirements. The authorities are then contacted as part of the ISM audits or the Safety Case. A 400 References a) SOLAS b) IMO Guidelines for Hyperbaric Evacuation c) DNV-DS-E404 (standard under development) A 500 Procedural requirements, approval and certification 501 Procedural requirements, Approval and Certification requirements are given in DNV-DS-E404 and DNV Rules for Ships Pt.5 Ch.16 Sec.7. A 600 Documentation 601 Contingency plans with details of responsibilities, equipment, systems and escape routes. A 700 Survey and testing requirements during and after manufacture 701 (See DNV-DS-E404) A 800 Survey and testing requirements during and after assembly 801 (See DNV-DS-E404) A 900 Survey and testing requirements during and after installation 901 (See DNV-DS-E404) A 1000 Marking and signboards 1001 (See DNV-DS-E404) A 1100 Materials 1101 (See DNV-DS-E404)
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 App.A – Page 70
APPENDIX A SELECTION OF SAFETY OBJECTIVE
A. Introduction A 100 General principles (informative) 101 The selection of the safety objective depends on the criticality of each of the elements that have an impact on the management of risks to the diving system. 102 Certification shall direct greatest effort at those elements of the diving system where the risk is highest and whose failure or reduced performance will have the most significant impact on safety and environmental risks. 103 Suitable selection factors include, but are not limited to, the: a) overall safety objectives for the diving system b) assessment of the risks associated with the diving and the measures taken to reduce these risks c) degree of technical innovation in the diving system d) experience of the contractors in carrying out the work e) quality management systems of the owner and it’s contractors. 104 Due to the diversity of various diving systems, their contents, their degree of innovation, the geographic location, etc.; it is not possible to give precise guidelines on how to decide what safety objective is appropriate for each particular diving system. Therefore, guidance is given as a series of questions that should be answered when deciding the appropriate safety objective for a diving system. This list is not exhaustive and other questions should be added to the list if appropriate for a particular diving system. 105 It must be emphasised that the contribution of each element should be judged qualitatively and or quantitatively. Wherever possible quantified risk assessment data should use to provide a justifiable basis for any decisions made. 106 Depending of the stage of the project, the activities may not have taken place yet in which case the questions can also be posed in another form, i.e. “Is …. planned to be?”
B. Trigger Questions B 100 Overall safety objective a) Does the safety objective address the main safety goals? b) Does the safety objective establish acceptance criteria for the level of risk acceptable to the owner? c) Is this risk (depending on the diving and its location) measured in terms of human injuries as well as environmental, economic and political consequences? B 200 Assessment of risk a) Has a systematic review been carried out to identify and evaluate the probabilities and consequences of failures in the diving system? b) Has this review judged the contribution of each element qualitatively and or quantitatively and used, where possible, quantified risk assessment data to provide a justifiable basis for any decisions made? c) Does the extent of the review reflect the criticality of the diving system, the planned operation and previous experience with similar diving systems? d) Does this review identify the risk to the operation of the diving system and to the health and safety of personnel associated with it or in its vicinity? e) Has the extent of the identified risks been reduced to a level as low as reasonably practicable by means of one or both of: f) Reduction in the probability of failure? g) Mitigation of the consequences of failure? h) Has the result of the systematic review of the risks been measured against the owner’s safety objective? i) Has the result of this review been used in the selection of the appropriate certification activity?
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B 300 Technical innovation a) Has the degree of technical innovation in the diving system been considered? b) Has it been considered that risks to the diving are likely to be greater with a high degree of technical innovation than with a diving designed, manufactured and installed to well-known criteria in well-known waters? c) Have factors been considered in the selection of the appropriate certification such as: — Degree of difficulty in achieving technical requirements? — Knowledge of similar diving systems? — Effect of the new diving system on the area or vessel? B 400 Contractors’ experience a) Has the degree of risk to the diving system been considered where design, construction or installation contractors are inexperienced? b) Has the degree of risk been considered where the contractors are experienced but not in similar work? c) Has the degree of risk been considered where the work schedule is tight? B 500 Quality management systems a) Have all parties involved in the diving system implemented an adequate quality management system to ensure that gross errors in the work are limited? b) Do these parties include the: i) Owner ii) Design contractor iii) Construction contractors iv) Sub-contractors v) Installation contractor vi) Operator (when relevant) c) Do the factors being considered when evaluating the adequacy of the quality management system include: i) Whether or not an ISO 9000 or equivalent certified system is in place? ii) Results from external audits? iii) Results from internal audits? iv) Experience with contractors’ previous work? v) Project work force familiarity with the quality management system?
C. Systematic Review/Analysis C 100 What to do and how? (informative) 101 Submitted so called “FMEAs,” reveal that there appears to be a misconception of how to approach the Systematic Review required in Sec.2. 102 Hazards identification and risk assessment involves a series of steps as described in DNV-OS-A101 Appendix B for Formal Safety Assessment and includes: Identification of the hazard, Reduction of the likelihood & Reduction of the consequence. Alternative standards include ISO 17776:2000(E) that may also give adequate guidance. 103 The correct choice of tools, in the correct order, is paramount to a systematic review and ISO 17776 - “4.5 Selection of structured review techniques” and “Annex B” - describes this. 104 When the tool is chosen, it is important to report the results of the analysis in the appropriate format for the chosen tool: a) It makes no sense reporting a HAZID in the format of a FMEA, or vice versa. b) The safety objectives need to be clearly defined and verifiable. c) The scope of the analysis and boundaries of the diving system shall be clearly defined. d) The actions given in the analysis when dealing with failures are critical to safety. Operating procedures and crew familiarisation/Handover procedures should be reviewed to ensure crew can adequately handle the failure scenarios should they occur.
DET NORSKE VERITAS AS DNV Standard DNV-DS-E403, July 2012 App.A – Page 72 e) Failure modes where maintenance is listed as either detection or mitigation should be collated as a table for input into the planned maintenance system. f) Is there anything else on the vessel which may impact the system? ICE Class, Helideck, Well Intervention etc. g) It should also be shown who was involved in the preparation of the analysis. 105 A typical, but not exhaustive, list of hazards/failures includes: a) outer or inner area fire b) releases with potential to result in fires c) explosions, and/or toxic hazards d) loss of pressure containment e) contamination of living environment f) loss of power to the diving system g) failure of handling systems h) loss of communication to/from the diving system 106 Note that correct syntax is required to effectuate a correct order of identification and evaluation of failures. a) A correct syntax in this case would be: “Failure A may lead to serious consequences therefore Mitigation X is implemented to arrive at less serious (consequences and/or probability) = Risk.” b) Wrong syntax is frequently stated as: “Failure A will not lead to serious consequences because of Mitigation X”. As this type of syntax is reversible (“Because of Mitigation X Failure A does not lead to serious consequence”), it frequently leads to an improper view of the risk and an early termination of the analysis process.
DET NORSKE VERITAS AS