Welding Innovation Vol. XVI, No.1, 1999

Tribute to a Leader

The James F. Lincoln Arc Welding Foundation was incorporated in 1936 as a nonprofit organization “…to encourage and stimu- late scientific interest in, and scientific study, research and edu- cation in respect of, the development of the arc welding industry…” During Dick's tenure as Executive Director of the Foundation, he enhanced the organization's effectiveness by:

• Supporting the School/Shop, College and Professional Award Programs with publicity and cash grants that have made them among the finest such programs in the United States • Expanding the program of donating complete libraries of books Richard S. Sabo published by the Foundation to high schools and colleges • In 1984, initiating publication of Welding Innovation, a periodical which now has an international circulation in excess of 50,000 Some people are simply irreplaceable. My long time friend and • In 1988, appointing the first International Assistant Secretaries colleague, Richard S. Sabo is a case in point. After 31 years of the Foundation with The James F. Lincoln Arc Welding Foundation, and 34 years • Establishing creative partnerships with the American and at The Lincoln Electric Company, Dick is retiring. He will be suc- Australian Institutes of Steel Construction to co-sponsor ceeded, but never replaced. welded bridge award programs For the last three decades, it has been my privilege to watch Dick • Continuing the Foundation's ambitious program of publishing inspire, educate and motivate a truly amazing range of people, welding manuals and design texts from Lincoln employees to vocational school students, from top industry leaders to Foundation Award program participants, and The above accomplishments were very much a part-time activity for from college professors to members of Congressional committees. Dick over the years, since simultaneously he was serving Lincoln He started his professional life as a high school teacher and athlet- Electric as Director of Corporate Communications and later, ic coach after receiving a Bachelor's degree from California Assistant to the Chairman of the Board. Throughout his career, University of Pennsylvania, and a Master's degree from Edinboro Dick has traveled extensively, delivering over 1,200 speeches, often University. Although he left a traditional teaching career to become on themes that emphasized the importance of education, and/or the a pieceworker on the Lincoln Electric factory floor in 1965, Dick relationship between profit sharing and productivity. He has truly could not escape the role of educator for long. His natural abilities been an “Ambassador-at-large” for the entire welding industry. The flourished under Lincoln's unique Incentive Management system, American Welding Society recognized his contributions by naming and soon he found himself deeply immersed in publishing welding him the Plummer Lecturer in 1992, and the International Academy texts, showcasing Lincoln Electric on “60 Minutes,” and speaking at of Business Disciplines named him Business Executive of the Year meetings of the American Welding Society and the American in 1997. In 1992, Lincoln Electric made him “Employee of the Year,” Institute of Steel Construction. His appointment to lead the James citing his many remarkable public relations achievements on behalf F. Lincoln Arc Welding Foundation in 1968 only broadened the of the company. scope of his educational mission. To say that it is difficult for me to imagine The James F. Lincoln Having spent a lifetime in academia myself, I believe that per- Arc Welding Foundation without Dick Sabo's leadership would be sonal example is one of the best teachers. In this respect, Dick an understatement. But of course, the Foundation will continue is head and shoulders above the crowd. His strong work ethic, to carry out its important mission of advancing arc welding constant focus on results, ability to be a team player, and unfail- design and practice worldwide. I came across a quote from ingly positive attitude are evident to all who meet him or hear Walter Lippman that summed up my thoughts about Dick quite him speak. But get to know him a little better, and Dick will well: “The final test of a leader is that he leaves behind in other eagerly tell you what has really made his life worthwhile: mar- men the conviction and the will to carry on.” How true. riage to his high school sweetheart Gail, raising their four chil- dren together, and now, enjoying their grandchildren. No one Donald N. Zwiep, Chairman could point to a better example of a life well and fully lived.

THE JAMES F. LINCOLN ARC WELDING FOUNDATION TRUSTEES & OFFICERS Dr. Donald N. Zwiep, Chairman John T. Frieg, Trustee Leslie L. Knowlton, Trustee Roy L. Morrow Duane K. Miller, Sc.D., P.E. Worcester, Massachusetts Cleveland, Ohio Cleveland, Ohio Executive Director Secretary Cover: The Berri Bridge in South Australia won the 1998 $10,000 Australasian Steel Bridge Award jointly sponsored by the Australian Institute of Steel Construction and the James F. Lincoln Arc Welding Foundation.

Omer W. Blodgett, Sc.D., P.E. Award Programs Design Consultant 12 1998 Awards for Engineering Volume XVI and Technology Students Number 1, 1999

Editor Duane K. Miller, Features Sc.D., P.E. 2 Harmonization of European Welding Standards Assistant Editor R. Scott Funderburk Reaching agreement on European welding standards—a progress report.

The James F.Lincoln 21 A Steel Bridge Over the River Murray Arc Welding Foundation Constructed using an innovative launching technique, the Berri Bridge successfully links two South Australian townships.

The serviceability of a prod- Departments uct or structure utilizing the type of information present- ed herein is, and must be, 7 Opportunities: 1999 Professional Programs the sole responsibility of the builder/user. Many vari- Register early for Lincoln Electric's Design and Production Welding Seminars. ables beyond the control of The James F. Lincoln Arc Welding Foundation or The 8 Key Concepts: A Look at Heat Input Lincoln Electric Company affect the results obtained in applying this type of infor- mation. These variables 16 Design File: Watch Out for “Nothin’ Welds” include, but are not limited to, welding procedure, plate chemistry and temperature, weldment design, fabrica- 19 Arc Works™ Seminar tion methods, and service In response to customer requests, Lincoln offers a comprehensive requirements. new seminar on making optimum use of ArcWorks™ software.

Visit Welding Innovation online at http://www.lincolnelectric.com/innovate.htm

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Welding Innovation Vol. XVI, No. 1, 1999 1 Harmonization of European Welding Standards

By Ralph B. G. Yeo, Intnl. Asst. Secretary The James F. Lincoln Arc Welding Foundation United Kingdom

Background and certification. The governing nization work was started in a particu- European Council, whose members lar area, the modification of relevant Sir Winston Churchill’s 1946 vision of are the heads of states and govern- national standards would cease. The “The United States of Europe” eventu- ments of the member states, instruct- harmonized standards, identified by ally led to the harmonization of ed the European Commission (the civil their EN numbers, contain identical European welding standards. He antic- servants) to accelerate the process of information, published in English, ipated that a close alliance of harmonization. (The elected European nations would soften the European Parliament has responsibili- nationalism and social unrest that ty mainly for budgetary affairs.) The The fundamental were major causes of World Wars I Council issues Harmonization feature of ENs is that and II. The Treaty of Rome, signed in Directives, proposed by the they are stand-alone 1957, set up the European Economic Commission, to be incorporated into Community (EEC) to encourage the the statutory systems of the various documents free movement of capital, goods, ser- nationalities, and with which standards vices, and people. The success of the must comply. Some were instituted EEC led to the formation in 1960 of without delay, but many of the most German, and French. They are identi- the European Free Trade Association significant barriers persisted because fied as BS EN, DIN EN, and AFNOR (EFTA) of countries around the periph- of different approaches to engineering EN, respectively, in Britain, Germany ery of the EEC. Recently, a number of standards, type testing, and profes- and France. Other languages require newly-independent Eastern European sional qualifications. They required their own translations. When pub- countries have applied for European agreement before they could be lished, a European standard has the Union (EU) membership. The EU now installed across the EU. The major status of a national standard, and any has more than 370 million inhabitants, authorities dealing with harmonization conflicting national standards are with- and significant further growth is are CEN (Comité Européen de drawn. inevitable. Normalisation, European Committee for Standardisation) and CENELEC In addition to the work on standards, a An essential component of the EU is (Comité Européen de 1993 CE Marking Directive and the Single Market and its elimination Electrotechnique, European Decision set out general harmonized of all trade barriers. The European Committee for Electrotechnical conformity assessment procedures. Coal and Steel Community (Belgium, Standardisation), both of which have One of the significant benefits of har- France, West Germany, Italy, and representation from the member coun- monization is that approval of a prod- Luxembourg) which was formed in tries. CEN deals with codes, materials, uct by a suitable testing authority 1951, reached the earliest effective and methods. CENELEC is responsi- renders the product satisfactory in accords. The elimination of customs ble for electric welding equipment. other EU countries, regardless of barriers in 1993 led to significant whether it is made locally or imported. increase in cross-border trade of alco- Technical Committee 121 of CEN tack- Conformance with standards and hol and tobacco products, but was led the formidable tasks required to directives, such as those for personal less effective in encouraging the reach agreement on welding stan- protective equipment, is certified and movement of engineering products. It dards. Several important ground rules indicated by an attached CE mark. was recognized that attention needed were adopted. Where possible, exist- The product can then be sold through- to be given to the more pervasive, but ing ISO standards would be adopted, out the EU without further national effective, technical barriers, mainly using the ISO number preceded by 2, standards assessments. engineering standards, type testing, such as EN 29000, and when harmo-

2 Welding Innovation Vol. XVI, No. 1, 1999 European standards are entirely differ- EN 10155: 1993, Structural steels with dered joints - Symbolic representation ent in structure, content, and designa- improved corrosion resistance. on drawings. The concept of prequali- tion from those adopted by AWS and fied joints has not been accepted in ASTM, although American standards EN 10210: 1997, Hot formed welded Europe. Most structural steelwork are widely known and used in Europe. structural hollow sections of non-alloy contracts require the use of approved This paper provides an introduction to and fine grain steels. welding procedures, leading to exces- the major engineering standards that sive test costs (often incurred because apply to welded fabrications. EN 10219: 1997, Cold formed welded of inadequate documentation) and structural hollow sections of non-alloy relatively slow adoption of more Overall Organization of and fine grain steels. productive new methods. European Standards The grade designations for steels are Welding Practices The fundamental feature of ENs is that informative and provide guidance to they are stand-alone documents, and designers and fabricators. The desig- Welding practices for different materi- it is estimated that 300-400 standards nations include indications of nominal als are covered by the various parts of will be required for welding and NDT! yield strength (mainly 235, 275, 355, EN 1011, Recommendations for weld- For instance, they include a specific 420, and 460 N/mm2 ), steel quality ing of metallic materials. Part 2, Arc standard for an operation as simple as (standard quality steel, deoxidation, welding of ferritic steels, which should the measurement of preheat tempera- etc,) 27J impact transition temperature be issued in 1999, is devoted to struc- ture. Whereas AWS D1.1 contains tural steels. It contains general recom- most of the welding information The concept of mendations for good welding required for steel structures, the equiv- practices, and a series of tables and alent Eurocode 3 contains little direct pre-qualified joints nomographs give estimates of pre- welding information but it refers to a has not been accepted heat temperatures to prevent cold series of other individual standards in Europe cracking, based on the principles which fall into groups to cover design, included in BS 5135: 1984, Process of weld engineering, production, and arc welding of carbon and carbon quality. (R=20°C, O=0°C, 2=-20°C, L=-50°C), manganese steels. Those principles steelmaking additions, and if applica- involve the concepts of carbon equiva- Application Standards ble, method of production, and suit- lent, weld metal diffusible hydrogen, (Design Codes) ability for a particular application, e.g., combined thickness, and heat input. cold forming. Steels can be supplied in Combined thickness is measured at A series of design codes to cover the the Normalized (N), Normalized Rolled 75 mm from the joint line (Figure 1). basis of design and actions on struc- (NR), or Thermomechanically Rolled Preheat temperature is estimated from tures are in the draft for development (TMR) conditions. nomographs that relate minimum pre- stage, and will appear as a series heat temperatures required to avoid ENV 1991-1999. DD ENV 1993: All European structural steel standards cracking with combined thickness and Eurocode 3, covers the design of steel require the use of a full designation to heat input for different combinations of structures. These codes themselves indicate the combination of the product will contain very little welding informa- form and the grade. For example, plate tion, but reference will be made to or sections with yield strength of 355 other individual standards dealing with N/mm2, impact toughness of 27J@ steels, welding practices, welding pro- -20°C, suitable for cold forming are cedures, approvals, etc. designated: BS EN 10025: 1993, Grade S355K2G4C. Steel The maximum carbon equivalent val- The following group of standards ues (CEVs) of the various grades are covers weldable structural steels: specified to assist in estimating pre- heat (from EN 1011-2, when issued). EN 10025: 1993, Hot rolled products of non-alloy structural steels. Joint Types EN 10113: 1993, Hot rolled products in Joints should be specified using sym- weldable fine grained structural steels. bols and principles from EN Figure 1. Measurement of combined 22553:1995, Welded, brazed and sol- thickness (CT).

Welding Innovation Vol. XVI, No. 1, 1999 3 ments is satisfied and the previous BS EN 439: 1994, Shielding gases for procedure approvals are relevant to arc welding and cutting. Classification. the application and production work on which they are to be employed. Also, BS EN 499: 1994, Covered electrodes where additional tests have to be car- for manual arc welding of non-alloy ried out to make the approval techni- and fine grain steels. Classification. cally equivalent, it is only necessary to do the additional tests on a test piece BS EN 758: 1997, Tubular cored elec- which should be made in accordance trodes for metal arc welding with and with this standard. Although the AWS without a gas shield of non-alloy and welding positions are widely used in fine grain steels. Classification. Europe, EN 288 uses the designations shown in Figure 3. BS EN 756: 1995, Wire electrodes and wire-flux combinations for submerged Figure 2. Example nomograph for esti- Welder Approval arc welding of non-alloy and fine grain mating minimum preheat temperature. steels. Classification. The testing of welder skills is an CEV and weld metal hydrogen levels important factor in ensuring the quality BS EN 760: 1996, Fluxes for sub- (Figure 2). of the welded fabrication. BS EN 287, merged arc welding. Classification. Approval testing of welders for fusion Welding Procedures welding, Part 1: 1992, Steels, shows These standards cover the classifica- the criteria that must be satisfied to tion tests and resulting designations The former national standards for for yield strength and impact energy specification and approval of welding ...weld repairs can be (which are included in all the classifi- procedures were similar in nature but cations), welding position capability, their requirements differed in many made almost anyplace, characteristics of the flux (if present), details. The new ENs attempt to retain and in almost any and weld metal diffusible hydrogen. most of those national approaches to environment They also contain information specific procedure approval. The overall princi- to the individual processes: flux type ples are contained in EN 288: for shielded metal arc (SMAW), flux- Specification and approval of welding identify the ability of the welder to procedures for metallic materials, make specific welds. Each criterion Part 1: General rules for fusion weld- included is considered to be a signifi- ing, the requirements of the welding cant factor in the approval testing, and procedures specifications are shown the ability of a welder to understand in EN 288, Part 2, Welding procedure the technology and to follow verbal or specification for arc welding, and the written instructions are further optional various testing procedures are cov- requirements in this standard. The ered in other parts. Part 3 1992, designation system devised for BS EN Welding procedure tests for the arc 287 approval was developed for com- welding of steels, specifies how a puterized identification of approved Welding Procedure Specification is welders, by means of a series of approved by making welding proce- abbreviated designations to identify dure tests for steels. Other methods the criteria. of procedure approval include the use of previous welding experience, Welding Consumables approved welding consumables, stan- dard welding procedures, and pre-pro- A harmonized set of European stan- duction welding tests, all of which are dards has been agreed upon for the covered in separate parts of EN 288. major process consumables.

The introduction of EN 288-3 does not BS EN 440: 1994, Wire electrodes and invalidate previous welding procedure deposits for gas shielded metal arc approvals made to former national welding of non-alloy and fine grain standards or specifications, providing steels. Classification. the intent of the technical require- Figure 3. EN welding position designations.

4 Welding Innovation Vol. XVI, No. 1, 1999 cored (FCAW) and submerged arc Table 2. Symbols used to classify weld designers) that refers to yield strength, welding (SAW); electrical requirements metal impact strength. impact toughness, and flux type, for and electrode efficiency for SMAW; 47J example, E 46 3 1Ni B. The full desig- shielding gas for FCAW and GMAW Transition, °C 20 0 -20 -30 -40 -50 -60 nation, E 46 3 1Ni B 54 H5, (required welding; characteristics of SAW fluxes; Table 3. Designation of welding and wire-flux combinations for SAW. Symbols A02 3 456 position capability. The symbols used to classify weld The common designation for positional metal yield strength are shown in capability is shown in Table 3. Table 1, and the minimum test temper- ature for 47J impact strength is shown Examples of designations of welding in Table 2. consumables are shown in Table 4.

Table 5 indicates examples of equiva- lent designations for some popular Table 1. Symbols used to classify weld grades. EN designations are informa- metal yield strength in EN standards tive but still unfamiliar and difficult to for consumables. remember. To make reference easier, Minimum YS, the SMAW and FCAW designations N/mm2 355 380 420 460 500 have a shortened compulsory partial Symbols 35 38 42 46 50 designation (information required by

Table 4. Examples of designations for welding consumables that deposit weld metal with minimum yield strength of 460 N/mm2and impact energy of 27J at -30oC in standardized classification tests.

Welding Innovation Vol. XVI, No. 1, 1999 5 Table 5. Comparison of AWS and EN classifications for popular grades. for three systems (levels) of welding quality control, the requirements for which are shown in further parts. Part 2 covers Comprehensive quality requirements, and is similar to the requirements of EN 29001 and 29002, with technically demanding contractual requirements. Part 3 covers Standard quality requirements with well-con- trolled predictable welding. Part 4 by fabricators) also includes their Welding Equipment covers Elementary requirements, operating characteristics. It is likely Manufacturers of welding equipment which entail minimum documentation that the AWS designations will contin- and the fabricators that use it must for simple and routine techniques. ue in Europe for some time, especially comply with regulations introduced for Certification showing conformance for SMAW electrodes. health and safety. The safety, noise with the requirements of EN 729 is emission, welding performance, and best sought from an accredited third- ...it is not as easy electromagnetic compatibility are cov- party organization. to substitute one ered by a number of standards and European consumable Harmonization Directives. Standards To ensure that suitable levels of weld- for power sources and other equip- ing technology and control are applied, for another ment have been drafted to conform to fabricators are required to show the the safety requirements of a series of availability of Welding Coordinators Compared with AWS standards, finding important Directives, especially those with suitable levels of knowledge set and using equivalents to AWS grades for low voltage and electromagnetic out in EN 719, Welding coordination, can be difficult, and caution is neces- compatibility. Compliance with the Tasks and responsibilities. Acceptance sary. Furthermore, it is not as easy to standards is indicated by the CE mark. of the categories of European Welding substitute one European consumable The important standards are shown in Engineer, European Welding for another. When impact testing is Table 6. In brief, the individual stan- Technologist, and European Welding required, an approval is valid only for dards conform to the Directives, result- Specialist (in decreasing order of edu- the specific make used in the proce- ing with details such as 80 V rms OCV cational requirements) is growing, but dure test. However, the additional for transformers, 113 V DC for recti- not uniformly, across the EU. European information on the chemical fiers, 55 V rms for hobby transformers, Conclusions nature of the fluxes can be very useful. etc. The noise emission limit is 96 dbA Consequently, the writer has found the but a lower level is being considered. The European Union is becoming combination of AWS and EN classifica- stronger and larger, and it will continue tions for a product to be a better guide Quality Control to grow as a unified producer and con- than the individual classifications. sumer. To ensure the safety and per- Welding belongs to the category formance of products to be sold termed “special” in EN 29000, without barriers across the Single Table 6. List of EU documents dealing because the results cannot be verified Market of the EU, such products will with welding equipment. entirely by inspection. Continuous have to meet a growing list of stan- monitoring and/or compliance with dards, only some of which could be documented procedures are required discussed briefly in this paper. to ensure that requirements are satis- Ignorance of those standards will be a fied. A series of standards devoted to significant barrier for suppliers from the control of weld quality has been within and outside the EU. developed. These have proved to be contentious and their implementation Acknowledgements is not comprehensive. EN 729, Quality requirements for welding, is published G. B. Melton, provided expert interpretation in four parts: Part 1, Guidance for of standards and directives for equipment. selection and use, provides guidelines

6 Welding Innovation Vol. XVI, No. 1, 1999 Opportunities Lincoln Electric Professional Programs

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Welding Innovation Vol. XVI, No. 1, 1999 7 Key Concepts in Welding Engineering

by R. Scott Funderburk

A Look at Input

What is Heat Input?

In arc welding, energy is transferred from the welding electrode to the base metal by an electric arc. When the welder starts the arc, both the base metal and the filler metal are melted to create the weld. This melting is possi- ble because a sufficient amount of power (energy transferred per unit time) and energy density is supplied to the electrode.

Heat input is a relative measure of the energy transferred per unit length of weld. It is an important characteristic because, like preheat and interpass temperature, it influences the cooling rate, which may affect the mechanical properties and metallurgical structure of the weld and the HAZ (see Figure Figure 1. Heat input influences cooling rate. 1). Heat input is typically calculated as the ratio of the power (i.e., voltage x current) to the velocity of the heat source (i.e., the arc) as follows: How is Heat Input welding cables (see Figure 2). The Measured? machine voltage, therefore, can be 60 EI used only for approximate calculations H = Heat input can not be measured 1000 S directly. It can, however, be calculated Heat input is a where, from the measured values of arc volt- relative measure of H = heat input (kJ/in or kJ/mm) age, current and travel speed. the energy transferred E = arc voltage (volts) I = current (amps) Arc Voltage during welding S = travel speed (in/min or mm/min) In determining the arc voltage (E), the voltage should be measured as close and, in the case of significant voltage This equation is useful for comparing to the arc as possible, as opposed to drops, may lead to heat input calcula- different welding procedures for a the value displayed on the welding tion errors. given welding process. However, heat machine voltmeter. Measuring the input is not necessarily applicable for voltage across the arc provides the Current comparing different processes (e.g., actual voltage drop across the welding The welding current (I) is measured SMAW and GMAW), unless additional arc. The welding machine voltmeter with either an inductance meter (tong data are available such as the heat reading is always higher than the arc meter) or a shunt with appropriate transfer efficiency (Linnert, 1994). voltage due to the resistance of the metering equipment. The current is

8 Welding Innovation Vol. XVI, No. 1, 1999 never fixed with respect to time, espe- Transient Values mentation of cooling rate and heat cially on a microsecond level. With For processes in which the voltage input a more accurate analysis proce- SMAW, the current is also a function and current vary significantly with time, dure may be required, including of the arc length, which is dependent such as short-circuiting GMAW, the instantaneously monitoring the volt- on the welder's skill. Therefore, the average values of these variables are age, current and travel speed to calcu- current used in the heat input calcula- used in calculating the heat input. For late the actual heat input. tions should be the average value. example, with GMAW-pulsed arc, the current is pulsed at a specified fre- Weld Size is Related Travel Speed quency from a minimum value (back- The travel speed (S) is the forward ground current) to the maximum value to Heat Input velocity of the arc measured in either (peak current). The average value The cross-sectional area of a weld is inches per minute or millimeters per between the maximum and minimum generally proportional to the amount of minute. Only the forward progress con- current and voltage will provide an heat input. This intuitively makes tributes to the travel speed. If a weaving approximate heat input value for these sense, because as more energy is technique is used, only the forward welding processes. supplied to the arc, more filler metal speed counts, not the oscillation rate. and base metal will be melted per unit For vertical welding, the upward or With SMAW, the resistance of the length, resulting in a larger weld bead. downward speed of the arc is used. The electrode changes as it is melted, If a welder makes one weld with a fast travel speed must be in terms of minutes which results in a voltage change. travel speed and another with a slow and not seconds for the dimensions to The temperature of the electrode also travel speed, keeping current and volt- balance in the heat input equation. age the same for both, then the weld The current made at the slower travel speed will When the travel speed is measured, is never fixed be larger than the faster one. The fol- the arc should be established for an lowing equation is an approximation amount of time that will produce an with respect to time for the fillet weld leg size based on accurate average speed. A continu- heat input (Miller, 1998): ous welding time of 30 seconds is increases while its length is reduced suggested. If this is not possible for during welding, both of which influence ω = H the production joint (e.g., short welds), the overall resistance. Average values 500 a test weld should be run on a mock- are used in this case as well. up joint that will provide a sufficient where, length to determine the travel speed. The transient nature of these factors is ω = fillet weld leg size (in) The travel speed accuracy with manu- usually not considered when calculat- H = heat input (kJ/in) al or semi-automatic welding is depen- ing heat input, and the averages are dent on the welder. However, with adequate for procedure qualification or Although the precise relationship automatic welding, the speed is set on simple comparison of welding proce- between heat input and fillet weld size the motor controlled travel carriage. dures. However, for scientific experi- also depends on other variables, including the process and polarity, this equation is a helpful tool, especially in creating and reviewing welding proce- dures. For example, if a minimum fillet weld size is specified, then the corre- sponding minimum heat input can be determined and controlled.

Cooling Rate is a Function of Heat Input The effect of heat input on cooling rate is similar to that of the preheat temper- ature. As either the heat input or the preheat temperature increases, the rate of cooling decreases for a given base metal thickness. These two variables interact with others such as material thickness, specific heat, density, and Figure 2. The arc voltage is always lower than the machine voltage due to the resistance of the welding cables.

Welding Innovation Vol. XVI, No. 1, 1999 9 Table 1. How Material Properties are Affected by Increasing Heat Input for SMAW thermal conductivity to influence the cooling rate. The following proportion- Property* Change ality function shows this relationship between preheat temperature, heat Yield StrengthÕÕ 30% input and cooling rate: Tensile Strength 10% ∝ 1

R Percent ElongationÕ 10% To H

Notch Toughness (CVN)Õ 10%, for 15 < H < 50 kJ/in where, Õ 50%, for 50 < H < 110 kJ/in R = cooling rate (°F/sec or °C/sec) Õ To = preheat temperature (°F or °C) Hardness 10% H = heat input (kJ/in or kJ/mm) * SMAW with a heat input range of 15 to 110 kJ/in. The cooling rate is a primary factor that determines the final metallurgical structure of the weld and heat affected zone (HAZ), and is especially impor- tied to the heat input, but is also signif- Welding Codes tant with heat-treated steels. When icantly influenced by the weld bead welding quenched and tempered size. As the bead size increases, As discussed previously, heat input steels, for example, slow cooling rates which corresponds to a higher heat can affect the mechanical properties (resulting from high heat inputs) can input, the notch toughness tends to and metallurgical structure in the weld soften the material adjacent to the decrease. In multiple-pass welds, a and HAZ of weldments. The AWS weld, reducing the load-carrying portion of the previous weld pass is Welding Codes have specific provi- capacity of the connection. refined, and the toughness improved, sions related to heat input for this very as the heat from each pass tempers reason. Below are the requirements How Does Heat Input the weld metal below it. If the beads for heat input from AWS D1.1 and are smaller, more grain refinement D1.5. Affect Mechanical occurs, resulting in better notch tough- Properties? ness, all other factors being even. AWS D1.1 Structural Welding Code — Steel Varying the heat input typically will Tests have been conducted with The AWS D1.1 Structural Welding affect the material properties in the SMAW electrodes and procedures that Code — Steel controls heat input in weld. The following table shows how provided heat inputs varying from 15 three areas: (1) qualified Welding the listed properties change with kJ/in (0.6 kJ/mm) to 110 kJ/in (4.3 Procedure Specifications, (2) minimum increasing heat input. An arrow point- kJ/mm) (Evans, 1997). This repre- fillet weld sizes and (3) quenched and

ed up, Õ , designates that the property sents a very large heat input range, tempered steels. increases as heat input increases. An which encompasses most applications arrow pointed down,Õ , designates that of SMAW. Qualified Welding Procedure the property decreases as heat input Specifications (WPSs) increases. Next to the arrow is the If the changes in heat input are rela- When heat input control is a contract approximate amount that property tively small, as opposed to those of requirement, and if the procedure changed from the minimum to maxi- the previous table, then the mechani- used in production has a correspond- mum value of heat input tested. cal properties may not be significantly ing heat input that is 10% or greater changed. In another study, no signifi- than that recorded in the Procedure Other than notch toughness, all of the cant correlation between heat input Qualification Record (PQR), then the mechanical properties show a monoto- and mechanical properties was estab- qualified WPS must be requalified nic relationship to heat input, that is, lished for submerged arc welding (AWS D1.1-98, Table 4.5, item 18). the mechanical property only increas- (SAW) with typical highway bridge This is primarily due to concerns es or decreases with increasing heat fabrication heat input levels of 50 to 90 regarding the potential alteration of input. Notch toughness, however, kJ/in (Medlock, 1998). In this case, the weld metal and HAZ mechanical increases slightly and then drops sig- the tests results did show varying properties. nificantly as heat input increases. The properties; however, no discernable change in notch toughness is not just trends were established.

10 Welding Innovation Vol. XVI, No. 1, 1999 Minimum Fillet Weld Sizes AWS D1.5 Bridge Welding Code Summary The code also controls the heat input The AWS D1.5-96 Bridge Welding Heat input is a relative measure of the by limiting the minimum size of fillet Code has provisions for heat input in energy transferred during welding. It welds (AWS D1.1-98, Table 5.8). two areas: procedure qualification and is a useful tool in evaluating welding According to the Commentary, “For fracture critical nonredundant members. procedures within a given process. non-low-hydrogen processes, the The cooling rate, weld size and materi- minimum size specified is intended to Procedure Qualification al properties may all be influenced by ensure sufficient heat input to reduce There are three different methods for the heat input. Some welding codes the possibility of cracking in either the qualifying procedures in D1.5: the place specific controls on the heat heat-affected zone or weld metal” Maximum Heat Input Method, the input. To ensure high quality in welded (AWS D1.1-98, para. C5.14). For mul- Maximum-Minimum Heat Input construction, it is important to under- tiple-pass fillet welds, the Commentary Method, and the Production Procedure stand and apply these principles when includes the following: Method. For the Maximum Heat Input notch toughness and HAZ properties Method, the heat input must be are to be controlled and when welding “Should fillet weld sizes greater than between 60% and 100% of the value high alloy steels. the minimum sizes be required for from the Procedure Qualification these thicknesses, then each indi- Record (PQR) used to qualify the References vidual pass of multiple-pass welds WPS (AWS D1.5-96, para. 5.12.1). ANSI/AASHTO/AWS D1.5-96 Bridge Welding must represent the same heat input With the Maximum-Minimum Heat Code. American Welding Society, 1996. per inch of weld length as provided ANSI/AWS D1.1-98 Structural Welding Code - by the minimum fillet size required Steel. American Welding Society, 1998. D1.1-98 controls heat Evans, G. M. and Bailey, N. Metallurgy of Basic by Table 5.8.” (AWS D1.1-98, para. input in three areas Weld Metal. Abington Publishing, 1997. C5.14). Graville, B.A. The Principles of Cold Cracking Control in Welds. Dominion Bridge Company, Quenched and Tempered Steels Input Method, the heat input must fall 1975. Linnert, G.E. Welding Metallurgy, Vol.1. When quenched and tempered steels between that of the two required quali- American Welding Society, pp.667-693, 1994. (e.g., A514 and A517) are to be weld- fication tests. If the Production Miller, D.K. and Funderburk, R.S. “Reviewing ed, the heat input, as well as mini- Procedure Method is used, the heat and Approving Welding Procedure mum preheat and maximum interpass input can only deviate from the PQR Specifications.” The National Steel Construction Conference Proceedings.New temperatures, must conform to the by the following: an increase of up to Orleans, AISC, 1998. steel producer's specific written rec- 10% or a decrease not greater than Medlock, Ronald D. Qualification of Welding ommendations (AWS D1.1-98, para. 30% (AWS D1.5, Table 5.3, item 17). Procedures for Bridges: An Evaluation of the 5.7). If high heat input welding is Heat Input Method. Thesis, University of Texas, May 1998. used, the HAZ can be significantly Fracture Critical Nonredundant Stout, R.D. and Doty, W.D. Weldability of Steels. weakened due to high temperatures Members 2nd Edition. Welding Research Council, pp. and slower cooling rates. However, Chapter 12 of D1.5 applies to fracture 39-43, 103-107, 217-218, 229-237, 1971. the requirement does not universally critical nonredundant members Welding Handbook, Vol. 1, 8th Edition. American Welding Society, pp. 32-34, 1987. apply to all quenched and tempered (FCMs). The minimum preheat tem- Welding Handbook, Vol. 4, 8th Edition. steels. For example, with ASTM perature for a FCM is selected based American Welding Society, pp. 43-45, 1998. A913 Grades 60 or 65, which are on the heat input, material grade and quenched and self-tempered, the thickness, and filler metal diffusible heat input limitations of AWS D1.1 hydrogen content (AWS D1.5, Tables paragraph 5.7 do not apply (AWS 12.3, 12.4 and12.5). Although the D1.1-98, Table 3.1 and 3.2, footnote 9 focus in chapter 12 of D1.5 is the mini- and 4, respectively). mum preheat temperature, the heat input value is an equally controlling variable.

Welding Innovation Vol. XVI, No. 1, 1999 11 JURY OF AWARDS

Pedro Albrecht Glen E. Johnson William Schmidt Donald N. Zwiep Professor of Civil Engineering Professor of Mechanical Professor of Mechanical Chairman of the Jury University of Maryland Engineering Engineering Chairman, The James F. Lincoln University of Dayton University of Arkansas Arc Welding Foundation

In addition to the following awards to undergraduate and graduate students, Dartmouth College University of Minnesota The James F. Lincoln Arc Welding Foundation also provided grants of $250 to Stanford University University of Wyoming the following universities in recognition of each Best of Program, Gold, Silver, University of Illinois Worcester Polytechnic Institute or Bronze Award received by students of that university:

UNDERGRADUATE DIVISION

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Restoring Functional Mobility in the Elderly Through In-Bed Exercise Solomon Diamond Thayer School of Engineering Dartmouth College Faculty: Francis E. Kennedy

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Drill Chuck Design Lawrence J. Baskett Irak U. Rosas Candace Norman-Riley Mechanical Engineering Dept. Stanford University Faculty: Drew V. Nelson

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Redesign of Toggle Stop Study of Fiber Optic Cable Cutting Process Henry Chou Jason Colwell Eugene Hahm Maitreya V. Madhyastha Carmen Hernandez Mechanical and Industrial Engineering Dept. General Engineering Dept. University of Illinois University of Illinois Faculty: J.W. Nowak Faculty: Henrique Reis

12 Welding Innovation Vol. XVI, No. 1, 1999 $500 Each

Redesign of a Two-Stage Axial-Flow Water Design, Manufacture & Test of a Full- Power Post Puller Pump Suspension Mountain Bike Randal W. Six Kevin V. Lung Jonathan W. Fairbanks Mechanical Engineering Dept. Kristian Pala Christopher M. Lambert University of Wyoming Joshua D. Rieke Keith M. Levesque Faculty: David Walrath Mechanical and Industrial Engineering Dept. Matthew D. Morin University of Illinois Mechanical Engineering Dept. Faculty: J.W. Nowak Worcester Polytechnic Institute Faculty: Raymond Hagglund

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Dual Wheel and Drum Service Stand Gunsmith Screwdriver Failure Mode Analysis Rocker Lever Adjusting Screw Christopher T. Key David Balsiger Charles Crouch Mike Melinkovich Craig Eastin Trevor Hutchinson Mechanical Engineering Dept. Kristine Forsythe Christopher Wahl University of Wyoming Mechanical and Industrial Engineering Dept. General Engineering Dept. Faculty: Donald F. Adams University of Illinois University of Illinois Faculty: J.W. Nowak Faculty: Edward Kuznetsov Transmission Downsizing Troy Shawgo Dishwasher Dryness Sensing System Seal Design in Automotive Coolant Valve Max Sutlin Brent Crossley Daniel Beedon David Weinberg Gregory Lyons Amy Leung General Engineering Dept. Heena Shah Carolyn Sperle University of Illinois General Engineering Dept. Stephen Stone Faculty: Daniel L. Metz University of Illinois General Engineering Dept. Faculty: J.V. Carnahan University of Illinois Water Pump Test Rig Design Faculty: H.S. Wildblood Sean Leonard Automated Figure Skate Profiling System Derrick Umphlett Michael Czarnota CCD Camera Project Vivian Vlamakis Thomas D. Hull Ryan Willkom General Engineering Dept. Balmes Tejeda Brian Willkom University of Illinois Mechanical and Industrial Engineering Dept. Joe Wagner Faculty: Daniel L. Metz University of Illinois Jason Samson Faculty: J.W. Nowak Mechanical Engineering Dept. Enhanced Control & Performance of Santa Clara University Hydraulic Valve Actuation Packaging System Design Faculty: Tim Hight Matthew Mickiewicz Sarah Beckman Brian p. Ramsey Joshua Benoist End Effector for Engine Subframe Pick & Jeffrey Wolven Melodie Luk Place Automation Mechanical and Industrial Engineering Dept. General Engineering Dept. Scott Zeeb University of Illinois University of Illinois Mechanical Engineering Dept. Faculty: J.W. Nowak Faculty: Deborah Thurston University of Florida Faculty: John Schueller Ice Slurry Secondary Refrigeration System Single Sided Hole-Making Method Performance Joshua Ibarra Vehicle/Work Palette for a Melt Manifold Dar-Lon Chang Donald India Assembly Angela McConnell Khris Richardson Paul T. Semones Collin A. Webb General Engineering Dept. Div. of Engineering and Technology Mechanical and Industrial Engineering Dept. University of Illinois John Brown University University of Illinois Faculty: W. Brent Hall Faculty: Kenneth W. French, Jr. Faculty: J.W. Nowak

Welding Innovation Vol. XVI, No. 1, 1999 13 $250 Each

Stereo Lithography Apparatus Trail Assessment Cart Lever-Power, a Mechanical Alternative for the Timothy J. Maguire Benjamin T. Blaine Wheelchair-Bound Charles Theurer Scott P. Hempey Kevin Brown Derek Hildreth Christopher J. Hintz Gabriel Monteon, Jr. Tony Mira Karen L. Rewak Chris Baker Mechanical and Industrial Engineering Dept. Mechanical Engineering Dept. Mechanical Engineering Dept. University of Massachusetts-Amherst Santa Clara University Santa Clara University Faculty: David Kazmer Faculty: Tim Hight Faculty: Tim Hight

Reactive Suspension Technology Wet Bench Linear Robot Hardwood Flooring Mill Improvements Giuseppe Sammartino Jeffrey M.L. Fontana Brian C. Striggow Mechanical Engineering Dept. Mechanical and Aerospace Engineering Dept. Mike McGinn University of Illinois-Chicago San Jose State University Mike Bryan Faculty: Farid M.L. Amirouche Faculty: Burford Furman Lee Taliaferro Biological and Agricultural Engineering Dept. Suspension Actuation System for University of Georgia Mountain Bikes Faculty: Mark Evans Brian D. Ghidinelli Clayton Woosley Mechanical Engineering Dept. Santa Clara University Faculty: Tim Hight

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14 Welding Innovation Vol. XVI, No. 1, 1999 $750 Each

300 mm Edge-Handling Wafer Chuck Hard Disk Drive Actuator Pivot Design Jesse Adams Jessica Barzilai Greg Arcenio Brett Cryer Sue Smith Robert Floersheim George Sya Jonathan Switke Mechanical Engineering Dept. Mechanical Engineering Dept. Stanford University Stanford University Faculty: Mark Cutkosky Faculty: Larry Leifer/Mark Cutkosky

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Refinement and Implementation of a ABC Motors Entry System Inelastic Stability of Tapered Structural Virtual Keyboard Craig Litherland Members Wayne Fu Alexander M. Asseily Gabriel A. Jimenez Lopez Larisa Migachyov Gabriel N.H. Brinton Civil Engineering Dept. Scott Vance Gabriel Aldaz University of Minnesota Mechanical Engineering Dept. Mechanical Engineering Dept. Faculty: Theodore V. Galambos Stanford University Stanford University Faculty: Larry Leifer Faculty: Mark Cutkosky

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Personal Medical Instruments The Dylster Commuter Garment Bag Over-running Ratchet and Pawl Clutch Dirk Duffner Stephen Wahab Gregory M. Roach Ray Lathrop Derek Wolfe Scott M. Lyon Feng Ling Michael Z. Wong Mechanical Engineering Dept. Julie Schneider Mechanical Engineering Dept. Brigham Young University John Yen Santa Clara University Faculty: Larry L. Howell Mechanical Engineering Design Div. Faculty: Tim Hight Stanford University Faculty: Larry Leifer Automotive Haptic Electronic Ignition System Economics of Drying Willow Biomass Thomas Leung Prior to Burning Sajan Shetty Chamornwut Tamnarnchit Woong Sun Mechanical Engineering Dept. Chau Nguyen Cornell University Mechanical Engineering Dept. Faculty: Wesley W. Gunkel Stanford University Faculty: Larry Leifer/Mark Cutkosky

Welding Innovation Vol. XVI, No. 1, 1999 15 Design File

Watch Out For “Nothin’ Welds”

Practical Ideas for the Design Professional by Duane K. Miller, Sc.D., P.E.

A “nothin’ weld” - now there's a term you won't find in AWS T-Joints with Poor Fitup A2.4 Standard Welding Terms and Definitions! But Under ideal circumstances, the two members that consti- designers, fabricators and engineers need to know about tute the T-joint should be brought as closely into contact as “nothin’ welds” since they can lead to disastrous results. possible before those members are joined with a fillet weld. Along the length of a T-joint, perfect fit is never possible, What is a “nothin’ weld?” For the purposes of this discus- and so some small gaps will exist. Larger gaps may be tol- sion, a “nothin’ weld” is one that has essentially no throat, erable in certain situations. However, as the size of the and yet the external, visually discernible characteristics of gap between the two members increases, and if the fillet the connection give all indications that the expected weld, weld leg size is kept the same, the actual weld throat complete with the expected weld throat, has been decreases. This is illustrated in Figure 1. Taken to the achieved. Unlike a weld that is undersized or filled with extreme, this gap could approach the same dimension as surface-breaking porosity that would alert an inspector to the fillet weld leg size, creating a “nothin’ weld.” Externally, the need for more thorough scrutiny, “nothin’ welds” look the weld may look identical to that of a properly prepared just like the intended weld. joint. Figure 1 shows the increased stress level that results from the applied load on the decreasing throat size. It The capacity of any weld is a function of the following: should cause little surprise when such welds fail in service. length x throat x allowable strength. Regardless of the allowable weld strength or the length of the weld, if the The AWS D1.1-98 Structural Welding Code addresses the weld throat is zero (or nearly zero) the connection has no issue of fitup in paragraph 5.22.1, which states, “The parts load carrying capacity. “Nothin’ welds” have weld throats to be joined by fillet welds shall be brought into as close that approach zero, so the structural or mechanical implica- contact as practicable... If the separation is greater than tions can be disastrous. 1/16 in (1.6 mm), the leg of the fillet weld shall be increased by the amount of the root opening, or the con- Four examples of “nothin’ welds” will be cited, their causes tractor shall demonstrate that the required effective throat discussed, and the practical means by which they can be has been obtained.” This principle is illustrated in the final avoided will be explained. Finally, an actual case study schematic of Figure 1, and as illustrated by the numbers in will be presented. the Table, acceptable stress levels can be maintained when the appropriate compensation is made.

Figure 1. Increasing the root opening of a T-joint without increasing the fillet weld size increases the stress on the throat.

16 Welding Innovation Vol. XVI, No. 1, 1999 The most straightforward method to avoid this type of “nothin’ weld” is to obtain good fitup. When good fitup can- not be achieved, it is important to note those joints that contain areas of poor fitup so that compensation can be made for these conditions. This requires an effective visual inspection program that includes pre-welding inspection.

Fillet Welds and Lap Joints A second example of “nothin’ welds” occurs when fillet welds are put on the edges of lap joints where the member with the vertical edge of the fillet weld is relatively thin, typi- Figure 3. Examples of square edged joints, including the cally less than 3/8 in (10 mm). designer’s expectation and what actually can be delivered in production. While this is less of an issue with the commonly used semi-automatic welding processes of today, welders using SMAW electrodes (with their inherently broader arc) can Square-Edged Groove Welds inadvertently melt away the top edge of the member. This creates an illusion of a full-sized fillet weld equivalent to the On a square-edged groove weld, the base metal at the thickness of the top plate. In reality, and as illustrated in joint is not beveled or prepared in any other way. A gap Figure 2, the resulting weld throat may be much smaller may be provided between the two members to be joined, than the designer intended. resulting in a root opening that helps facilitate joint penetra- tion. In other cases, the joint may be butted tight, and joint penetration is fully dependent upon the penetration sup- plied by the welding process. Figure 3 illustrates how a “nothin’ weld” can occur with square-edged groove welds. While the designer expected a complete joint penetration weld like that in the top illustration, a combination of vari- ables can lead to the partial joint penetration weld shown in the lower example. In the extreme, the strength of the con- nection may be due only to the surface reinforcement. Yet, the visually discernible weld on the surface cannot be used to gauge the likely degree of penetration that has been achieved.

The D1.1 places fairly severe restrictions on the use of these joint types. For example, prequalified joint details B-P1a, B- P1b and B-P1c are limited to a maximum thickness of 1/4 in. All other thicknesses require some type of joint preparation, Figure 2. Melting top edge of lap joint can misrepresent whether the intended weld is a complete joint penetration actual throat. groove weld or partial joint penetration groove weld. For non-D1.1 Code work, or when using non-prequalified joint The AWS D1.1 Structural Welding Code addresses this by details, it is possible to successfully make CJP groove welds calling for maximum fillet weld sizes on the edges of lapped on materials as heavy as 1 in (25 mm) thick if welded from members as stated in paragraph 2.4.5: “The maximum fillet both sides, even when a square-edged groove weld is weld size detailed along edges of material shall be the fol- employed. However, rigorous control must be placed on the lowing: (1) the thickness of the base metal, for metal less welding procedures used in production, and electrode place- than 1/4 in (6.4 mm) thick; (2) 1/16 in (1.6 mm) less than ment with respect to the joint is critical. Spot checks of pro- the thickness of base metal, for metal 1/4 in (6.4 mm) or duction parts are highly recommended to ensure that the more in thickness…” This is not applied to the thinner production system is sufficiently robust to ensure consisten- members because, from a practical point of view, these cy. Alternately, groove weld details that employ prepared welds normally achieve the full throat thickness. The most surfaces for vee and beveled groove details, for example, straight-forward way to avoid the creation of this “nothin’ can be employed to avoid this form of a “nothin’ weld.” weld” is to leave the 1/16 in (1.5 mm) unwelded portion above the upper weld toe. Additionally, welders should be taught of the implications of this practice and be discour- aged from melting the top edge.

Welding Innovation Vol. XVI, No. 1, 1999 17 Metal Removal Operations Sometimes “nothin’ welds” are created by machining or grinding operations that are performed after the weld is made. Often in this situation, a weld is deposited that is fully compliant with the design intent, but a significant portion of the weld throat is reduced by a metal removal process. Overcoming this problem is fairly simple: the designer must

Figure 5. Weld with adequate throat. of the skewed joint created a narrow included angle. The designer expected a PJP groove weld with a reinforcing fil- let weld would be applied. To ensure this, welding proce- dures were developed that assured adequate penetration as long as the part was welded in the flat position. See Figure 5.

However, during production a “nothin’ weld” was created. Although all the facts will probably never be known, it appears that the welder chose to perform this operation in the horizontal position, minimizing penetration into this groove, yet resulting in a “nothin’ weld” with virtually no throat that was visually indistinguishable from the expected fillet weld. See Figure 6.

Figure 4. When machining weld metal, tolerances are critical. consider the final connection, after machining of the part, and make sure that the required weld throat will be main- tained in those conditions. It is essential that the designer consider all the tolerances that could accumulate, resulting NO FUSION in maximum metal removal, and verify that even under these conditions, adequate weld throats will be maintained. Figure 6. A “nothin’ weld.”

Figure 4 illustrates how these problems can arise, and the Four of these brackets supported a bearing cartridge that important role that tolerances play in avoiding the creation was part of a rotating machine. After several dozen hours of these problems. Perhaps one reason that this occurs is of operation, the welds on one bracket failed, followed by that the typical tolerances associated with many steel weld- failure of the corresponding welds on the other three brack- ing applications may be in the general magnitude of ±1/8 in ets. When the bearing support was lost, the entire (3 mm), whereas machining tolerances may be much more machine was ruined. To overcome this problem, a rigorous rigorously controlled. in-process inspection and monitoring of the welding opera- tions was initiated to ensure that the welder made the Case Study welds in the prescribed position. After-the-fact weld inspection was obviously incapable of detecting this This case study is basically an example of the first type of “nothin’ weld.” “nothin’ weld” that was described: a fillet weld in a poorly fit joint. What compounded this problem further is that poor Conclusion fitup was inherent to the detail that was selected. A part was stamped from 3/16 in (4.8 mm) sheet metal, formed “Nothin’ welds” can be avoided by proactively anticipating into a channel, and assembled into a skewed joint configu- the unexpected, and taking specific measures to ensure ration. To minimize cost of material preparation, the end of that the expected weld throat is consistently delivered in the inclined member had a 90° edge. Due to forming toler- the finished product. ances, fitup would never be exact and the inclined nature

18 Welding Innovation Vol. XVI, No. 1, 1999 S EMINAR

Course Content Location • How to Prepare and Review WPSs Within the AWS D1.1 Code All seminars will be conducted at the Lincoln Electric • ASME Section IX WPS Requirements Company World Headquarters, Cleveland, Ohio, U.S.A. • Arc Works Software Training - Arc Works AWS D1.1/D1.5 Registration Information - Arc Works ASME Section IX The registration fee should accompany your application. - WeldSelector For your convenience, the fee may be charged to your - FerritePredictor VISA or MasterCard account. If paying by credit card, - WeldCAD you may fax your registration to (216) 383-8025. - WeldCalculator For further information about the Seminar or any other Who Should Attend? Lincoln Electric Professional Program, call the registrar at (216) 383-2430. Thank you. • Quality Control Managers • Welding Foremen • Welding Superintendents • Welding Engineers • Plant Managers • Inspectors • Independent Consultants • Test Labs • Auditors

Please cut along dotted line and mail this portion with payment to: THE LINCOLN ELECTRIC COMPANY, ARC WORKS SEMINAR-WELD TECH., 22801 ST. CLAIR AVE., CLEVELAND, OH 44117-1199

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Welding Innovation Vol. XVI, No. 1, 1999 19 Cancellation Policy Hotel A full refund will be issued if notice of cancellation is A block of rooms has been reserved at the Four Points received by the registrar 7 days prior to the seminar. Hotel Sheraton, 28500 Euclid Avenue, Wickliffe, Ohio 44092. Their phone number is (440) 585-2750.

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Y OUR I NSTRUCTORS

Duane K. Miller, Sc. D., P.E. Harry A. Sadler Manager, Engineering Services Manager, Application Engineering

Instructor of AWS D1.1 WPS Instructor of ASME Section IX WPS Duane Miller is currently serving as the Harry Sadler currently serves on the vice-chair of the American Welding Pressure Vessel Research Council, the Society’s Structural Welding Code Board of Directors of the Welding Committee and is a past co-chair of the Research Council, and is a member of AWS Bridge Welding Committee. He has lectured the Materials Subgroup of the Section IX Subcommittee and conducted seminars in the United States, Asia, of the ASME Boiler and Pressure Vessel Committee. Mr. Australia and Africa. He is currently involved with the Sadler earned his BS Degree in Metallurgy from Penn FEMA-funded SAC research effort investigating seis- State University and is a member of the American mic issues. Dr. Miller previously served as chair of Welding Society, American Society of Mechanical the AWS Presidential Task Group on the Northridge Engineers, and is a former Certified Welding Inspector. Earthquake Welding Issue. He has authored many As manager of Applications Engineering, he is responsi- papers and magazine articles, as well as two hand- ble for evaluating customer’s welding applications, proce- books on various aspects of welding technology. dures, equipment, and consumables in order to improve quality, functionality, and/or reduce fabrication costs.

Walter D. Bullock Software Engineer, Arc Works Group Lincoln is proud to host this seminar per our Instructor of Arc Works Products customers’ requests. We want you to get as much Walter Bullock is a lead designer of Arc out of this seminar as possible. Please let us Works Software Products. Not only an know if there is anything we can do to make your expert in programming, Walter has solid learning experience more worthwhile. code knowledge on associated prod- ucts. He often works with customers to be sure that Thank you, their needs are implemented as solutions in making Arc Works the best product available on the market. Due to many customer requests, he is our preferred instructor of the Arc Works Seminar. Theresa Spear Arc Works Product Manager

20 Welding Innovation Vol. XVI, No. 1, 1999 A Steel Bridge Over the River Murray

By Ian Ide, Principal Vic Nechvoglod, Senior Bridge Engineer Connell Wagner Pty Ltd Adelaide, Australia David O’Sullivan, Director Built Environs Pty Ltd Adelaide, Australia Stefan Ahrens, Manager Ahrens Engineering Sheaoak Log, Australia

Introduction The Berri Bridge over the River Murray Figure 1. was needed to provide a direct road link between the Riverland townships of Loxton and Berri, some 200 km (125 mi) northeast of Adelaide in The Design Approach which could be readily extended to South Australia. With a proposal put achieve the required pile capacity even together by Built Environs Pty Ltd and The design approach to the Berri with the eleven pile design configura- Connell Wagner Pty Ltd, this was the Bridge involved a cooperative effort by tion. The use of steel tube piles also first private sector initiated major the designer, the contractor and the facilitated a modification of the pilecap bridge infrastructure project in South steel fabricator from the very inception forms to allow construction of the pile- Australia. Planning consumed more of the project. The final design was caps to continue when the river was at than two years, hundreds of hours, completed after consideration of an above-average level during a criti- and several hundred thousand dollars. the alternatives with regard to con- cal stage of erection. The planning phase included negotia- structability, steel fabrication, quality tions and discussions with various control, tolerances, and the construc- All the piers and pier crossheads were interest groups, some ten South tion risks associated with each compo- dimensionally identical, allowing for Australian government departments nent of the work. For example, the repeated use of forming and reinforce- and authorities, and the Department of final design for the fabrication of the ment details. This theme of risk con- Transport. The final proposal was for steel girders was not documented until trol and repeatability of form was a 330 m (1,083 ft) long bridge over the the fabricator verified production evident throughout the construction of River Murray, as well as approximately procedures, tolerances and testing the Berri Bridge. 1,500 m (4,900 ft) of approach roads, requirements, and had examined and embankment, and associated roadway commented on the proposed steel- Bridge Description structures, including an underpass. In work specification. the end, the project received unani- The Berri Bridge is an incrementally mous support from all sectors of the All pier pilecap footings were designed launched, composite steel girder and community, including the Aboriginal with identical pilecaps with eleven two-lane concrete deck bridge 330 m Community, which provided part of its piles each in order to manage con- (1,083 ft) in length, with eleven spans. reserve land for the Loxton abutment struction risks. Also, the river pier The spans vary from 20 m (65 ft) at (see Figure 1). piles were chosen to be steel tubes each abutment to 40 m (130 ft) at the

Welding Innovation Vol. XVI, No. 1, 1999 21 navigation span, with the typical span Bridge Girder Configuration the secondary but important role of measuring 33 m (108 ft). The bridge A four girder option was the minimum temporary support for the telescoping is straight in plan, but has a vertical cost solution, given the construction deck forms to ensure a weekly launch circular curve of 2,485 m (8,150 ft) method and the weight reduction cycle. radius (see Figure 2). achieved by using a minimum thick- ness deck. Typically, the girders are a Bearings The abutments are spread footings constant 1,395 x 23 mm (55 x 7/8 in) The pot bearings were designed to founded behind gravity retaining walls. web, 395 x 20 mm (15.5 x 13/16 in) meet service and launch loads. A The Berri abutment provides the longi- top flange, and 550 x 40 mm (22 x 1.5 number of configurations and types of tudinal fixed support. All piers are in) bottom flange. The bottom flange bearings were considered in the con- supported on piled footings. These was increased to 550 x 50 mm (22 x 2 cept stages and tests were carried out include bulb-base cast-in-situ driven in) at the main navigation span. All on some innovative concepts. steel is grade 300 L15, except the bot- Launching over the permanent bear- tom flange which is grade 350 L15. In ings using Teflonâ pads was finally A compact girder keeping with the theme of repeatability adopted as a proven economical design was adopted and simple detailing, the girders are option for the bridge. to ensure a limited made up of 68 fabricated beam seg- ments of equal length and camber, dif- Pier Redundancy state of girder fering only in the location of the The navigation span was required to flange yielding bracing cleats and bearing stiffeners. be 40 m (130 ft) to allow adequate clearing for shipping. The require- A compact girder design was adopted ments for ship impact on the bridge piles for land piers and driven steel to ensure a limited state of girder indicated the design vessel to be a tube piles for river piers. The capacity flange yielding. This was regarded as 1,760 tonne vessel traveling at 4 of these piles could be increased by a prerequisite for the redundant pier knots, with a river velocity of about extending the shaft and/or increasing philosophy since the navigation span one meter (3.3 ft) per second. All river the bulb-base as another risk control would increase from 40 m (131 ft) to a piers were designed to accommodate measure. maximum of 73 m (240 ft) if a pier this loading. were removed. The girder spacing Ian Ide, Principal of Connell Wagner, was chosen to ensure essentially even Connell Wagner recognized that the said, “The initial intention was that the loads on the bearings and piers under cost to construct the five river piers for bridge be a concrete box structure dead load. This was important during this loading was prohibitive and pro- with integral deck, although the option launching and for pier design under posed the concept of “pier redundan- of adopting steel girders with compos- the pier removed load case. cy” for the steel girder option. “Pier ite concrete deck was also exam- redundancy” means that if any pier ined...The decision to adopt the steel Bracing was selected to ensure that were removed, the bridge would not option was made shortly before the the girders would develop their full collapse and would continue to pro- final agreement was signed. This flange yield moment capacity. The vide limited service. “The steel option proved to be a winner.” girder web was designed to ensure is the only one suited to this concept that web buckling would not occur dur- because of its lightness and ductility,” After consideration of alternatives, an ing launching and included allowances explained Vic Nechvoglod, designer for early decision was made to adopt the for construction tolerances, for bearing Connell Wagner. He continued, “...the incremental launching technique as installation, girder soffit fabrication, superstructure has the overload the minimum cost solution for this and the casting bed assembly. capacity to carry limited one-way traf- bridge. In addition, it was judged that fic on the centerline of the bridge with this approach would reduce construc- In keeping with the principle of repeti- any one of the river piers removed. I tion time and risks, principally due to tion, all girders and bracings were believe this is the first bridge in the fewer construction activities being identical, and the girder web thickness world to be designed in this way.” required over water. The launching and top flange were selected to be operation for the 330 m (1,083 ft) constant for the full length of the Design for Repetition bridge was completed in just ten bridge. This allowed the use of “tele- The principle of repetition was funda- weeks. scoping” deck forms necessary to mental for economy in the design of achieve the planned weekly launch. nearly all components, including the The bracings were designed to serve piles, girders and pedestrian hand

22 Welding Innovation Vol. XVI, No. 1, 1999 rails. Designers worked closely with which would have been too heavy to system to enable a continuous launch the builder and fabricator on the handle. The segment length was of approximately 39 m (128 ft), at a design and detailing of all steelwork. incorporated into the final design after launch rate of about 12 m (39 ft) per Matters pertaining to fabrication of the consideration of costs by the fabrica- hour; and it would allow space for girders and detailing at minimum cost tor, construction staff and designer. guide frames on each pier to engage a were discussed several times before drop-down concrete panel in the deck the design was finalized. Fabrication To reduce on-site activity, time, and soffit, which provided guidance and initiatives included in the design were: costs, the girders were assembled in lateral restraint during construction pairs with the bracing installed in the and launch. • Trial welding of the flange to the web. painter’s yard after painting. The gird- • Flange butt welding, bracing cleat er pair assembly was then transported The design, including all construction and bearing stiffener welding. activities, was aimed at achieving a • A full scale mock-up of a girder one-week launching cycle. This was splice site weld. the steel girder achieved for eight of the nine launch- • Trial welding of sections to indicate es. Each launch cycle included the practical tolerances. superstructure field weld splicing of two segments to • Beam camber allowance for welding. is flexible and each of four girders (eight splices per • Inclusion of the fabricator’s input into torsionally soft launch), erecting formwork, fixing the final specification. reinforcement, pouring 39 m (128 ft) of deck, and installing 39 m of traffic In establishing the segment lengths, barrier and hand railing. trucking load limits and costs were to the site. Girder bracing was bolted reviewed, and the girders split into 17 to enable adjustment on site as an The concrete deck was poured on all equal lengths of just under 20 m (65 emergency procedure to meet launch but the first 30 m (98 ft) of girders. ft). The transport of segments longer tolerance requirements (see Figure 3). This 30 m section of undecked girders than that would have required police Bracing was provided in the outer two was designed to double as the “launch- escorts at substantial extra cost. To bays of the girders, leaving the central ing nose,” thus reducing construction reduce fabrication splicing costs, BHP bay completely clear. This clearance time and costs (see Figure 4). provided plates rolled to the required was designed to serve two main func- length, except for the 40 mm (1-5/8 in) tions: it would allow clear travel space Novel and innovative design for tem- and 50 mm (2 in) bottom flange plates, for the launching bracket and jacking porary works included a launching bracket for fixing the jacking system to the girders, and a lifting mechanism for the launch nose to raise it onto the bearings. Both were jointly developed by Built Environs and Connell Wagner and provide examples of the benefit of a cooperative approach in adapting designs to meet construction require- ments. In this case, the need for a special “launch nose” was avoided and construction costs were minimized by achieving 39 m (128 ft) continuous launch operations on a weekly cycle. The tops of piers, abutments and gird- er details were designed as an integral part of the launch bracket and jacking system at the design stage.

Figure 2.

Welding Innovation Vol. XVI, No. 1, 1999 23 Risk Management should be used to “proof” the pro- Conclusion At Berri, available site foundation infor- posed fabrication procedures and The Berri Bridge was completed on mation indicated that considerable set- welding with regard to tolerance and budget and two months ahead of tlement of the bridge approach camber. These four segments were schedule, despite delays that were embankments would occur during their designed for the undecked portion of caused by high river levels. Its open- construction. This posed a significant the launching nose and therefore ing was celebrated by a crowd esti- risk to construction by incremental could be used with increased camber mated at 10,000, including many launching, which required close con- tolerances. The first four segments residents of the Riverland townships of trol of all support bearings, including produced using the proposed fabrica- Loxton and Berri who had lobbied for the launch assembly bearings located tion procedures confirmed the initial thirty years for a bridge linking their on the approach embankment. The design camber predictions. communities. The bridge won the risk would have been particularly coveted Institution of Engineers grave in the case of a prestressed Notwithstanding this reassuring result, Excellence Award (South Australia) in concrete box type superstructure it was decided to maintain the beam 1997, the Institute of Building Award which typically requires tolerances of cross bracing as bolted connections, in 1998, and the 1998 $10,000 ± 1 mm (1/32 in) on bearing levels to rather than all-welded ones, as a “fall Australasian Steel Bridge Award jointly avoid damage during the launching back” precaution which allowed for the sponsored by the Australian Institute operation. on-site unbolted and level adjustment of Steel Construction and the James F. of the individual 20 m (65 ft) beam Lincoln Arc Welding Foundation. In comparison to a concrete box segments prior to field splicing, deck superstructure, the steel girder super- casting and launching. This turned out structure is flexible and torsionally soft, to be a prudent precaution, for while thereby allowing higher tolerance on 65 out of the 68 beam segments were bearing levels, and in the torsion or uniformly consistent in camber, three “twist” of the superstructure as a of the last few segments were out of whole. For the typical 33 m (108 ft) camber tolerance and had to be span at Berri, a differential pier level of “adjusted” prior to field splicing. The ± 5 mm (3/16 in) of the outer bearings problem appears to have been caused could be tolerated. Such flexibility by an error in a computer controlled allowed a margin for error and greatly reduced the risk in fabrication and construction of the superstructure. "Pier redundancy" This margin for error was built into the means that if any pier design as a “fall back” procedure in the were removed, event that specified fabrication and/or assembly tolerances were breached. the bridge would not For the Berri Bridge, a critical toleranc- collapse ing requirement was related to the girder soffit levels, which had to be within ± 3 mm (1/8 in) at any one web profiling machine. This potentially cross-section of the four girders. This costly and time-delaying deficiency in turn required that the specified cam- was managed with no pause in con- ber and camber tolerances for the 68 struction, and the incident serves to fabricated 20 m (65 ft) long beam seg- illustrate the management of risk in ments had to be closely controlled. It construction that is possible when was decided at the design stage that there is close cooperation between the first four of these beam segments designer, contractor and fabricator.

24 Welding Innovation Vol. XVI, No. 1, 1999 Figure 3

Figure 4

Welding Innovation Vol. XVI, No. 1, 1999 25 P.O. Box 17035 NON-PROFIT ORG. Cleveland, Ohio 44117-0035 U.S. POSTAGE The PAID James F. Lincoln JAMES F. LINCOLN Arc Welding ARC WELDING FND. Foundation