CERTIFIED WELDING SUPERVISOR MANUAL for · CERTIFIED WELDING SUPERVISOR MANUAL for ... Liquid...

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Transcript of CERTIFIED WELDING SUPERVISOR MANUAL for · CERTIFIED WELDING SUPERVISOR MANUAL for ... Liquid...

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CERTIFIED WELDING SUPERVISOR MANUAL

forQUALITY and PRODUCTIVITY

IMPROVEMENT

550 N.W. LeJeune Road, Miami, Florida 33126

Jack R. Barckhoff, P.E.Kenneth M. Kerluke, P. Eng.

Don L. Lynn, P.E.

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Contents

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Chapter 1—MANAGEMENT SYSTEMS FOR THE WELDING SUPERVISOR................. 1Introduction..................................................................................................................................1No System–System ......................................................................................................................3Lean Manufacturing.....................................................................................................................3Total Quality Management (TQM)..............................................................................................7Total Welding Management (TWM).........................................................................................10Conclusion .................................................................................................................................18References..................................................................................................................................18Review Questions ......................................................................................................................19Answers .....................................................................................................................................21

Chapter 2—REQUIREMENTS OF A WELD .................................................................... 23Introduction................................................................................................................................23Requirements for a Fillet Weld..................................................................................................23Objectives ..................................................................................................................................25Weld Terminology.....................................................................................................................25Weld Failure ..............................................................................................................................27Weld Size ...................................................................................................................................27Weld Length ..............................................................................................................................36Appearance and Weld Profile ....................................................................................................37Weld Soundness.........................................................................................................................38Mechanical Properties................................................................................................................44Corrosion Resistance .................................................................................................................46Achieving the Correct Requirements of a Weld ........................................................................47Welding Procedures ...................................................................................................................47References..................................................................................................................................50Guides and Exercises .................................................................................................................50Answers .....................................................................................................................................52

Chapter 3—SHIELDED METAL ARC WELDING (SMAW) ............................................. 53Introduction................................................................................................................................53Chapter Objectives.....................................................................................................................53Process Fundamentals................................................................................................................53SMAW Electrodes .....................................................................................................................56Features and Applications of SMAW Electrodes ......................................................................59Recommended SMAW Equipment ...........................................................................................62SMAW Essential Welding Variables ........................................................................................66SMAW Procedures and Techniques ..........................................................................................76Identify and Correct SMAW Defects ........................................................................................80Reference ...................................................................................................................................81Guides and Exercises .................................................................................................................81Answers .....................................................................................................................................86

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Chapter 4—GAS METAL ARC WELDING APPLIED TO MILD STEELS ....................... 87Introduction................................................................................................................................87Chapter Objectives.....................................................................................................................87What is Gas Metal Arc Welding? ..............................................................................................87Modes of Metal Transfer in GMAW .........................................................................................94Applications ...............................................................................................................................97Wire and Base Metal Melting ....................................................................................................99Wire Burnoff and Arc Length..................................................................................................104GMAW Essential Welding Variables......................................................................................105Summary of the Eight Essential Welding Variables ...............................................................130Equipment for GMAW ............................................................................................................130Find Out More .........................................................................................................................132Reference .................................................................................................................................132Exercises ..................................................................................................................................132Answers ...................................................................................................................................136

Chapter 5—FLUX CORED ARC WELDING APPLIED TO MILD STEELS................... 137Introduction..............................................................................................................................137Chapter Objectives...................................................................................................................137What is Flux Cored Arc Welding? ..........................................................................................137Process Fundamentals .............................................................................................................. 145Objectives ................................................................................................................................145Manufacture of FCAW Wires..................................................................................................145Classification of Filler Metals for FCAW of Mild Steel ......................................................... 147Electrode Size ..........................................................................................................................148Effect of Shielding Gases ........................................................................................................150Electrode and Base Metal Melting...........................................................................................153FCAW Essential Welding Variables .......................................................................................157Summary of the Seven Essential Welding Variables ..............................................................175FCAW Equipment ...................................................................................................................175Welding Techniques ................................................................................................................177Reference .................................................................................................................................180Exercises ..................................................................................................................................180Answers ...................................................................................................................................184

Chapter 6—THE SUBMERGED ARC WELDING PROCESS........................................ 185Introduction..............................................................................................................................185Advantages of SAW ................................................................................................................185Joint Tracking Methods ...........................................................................................................187Evolution of the Welded Joint .................................................................................................189Applications .............................................................................................................................191SAW Fluxes .............................................................................................................................191SAW Essential Welding Variables for Single Wire Applications...........................................195Effect and Control of SAW Essential Welding Variables .......................................................196Effect of Other Variables in SAW...........................................................................................199

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Reference .................................................................................................................................201Guides and Exercises ...............................................................................................................201Answers ...................................................................................................................................203

Chapter 7—STEEL METALLURGY............................................................................... 205Introduction..............................................................................................................................205Steelmaking .............................................................................................................................205Chemical Reactions in Steelmaking ........................................................................................206Important Elements in Plain Carbon Steels .............................................................................207Carbon in Iron..........................................................................................................................208Strengthening Methods ............................................................................................................210Alloying ...................................................................................................................................212Carbides ...................................................................................................................................212Effects of Manganese and Sulfur.............................................................................................214Effects of Aluminum ...............................................................................................................214Strengthening by Solid Solution ..............................................................................................214Strengthening by Precipitation Hardening...............................................................................216Grain Size Strengthening .........................................................................................................217Normalizing .............................................................................................................................218Fine-Grained Microalloyed Steels ...........................................................................................219Strengthening by Heat Treating ...............................................................................................221Effect of Alloy Additions ........................................................................................................221Mechanical Testing of Base Metals.........................................................................................226Weld Testing............................................................................................................................228Welding Metallurgy of Steels ..................................................................................................232Mechanical Properties of Welds ..............................................................................................232Hydrogen Cracking..................................................................................................................241Controlling the Hydrogen Content in the Weld.......................................................................243Preheating ................................................................................................................................245Postheating...............................................................................................................................247Controlling the Hardness of the Weld Zone ............................................................................248Weld Metal Cracking...............................................................................................................252Solidification Cracking ............................................................................................................252Find Out More .........................................................................................................................257Reference .................................................................................................................................257Exercises ..................................................................................................................................257Answers ...................................................................................................................................262

Chapter 8—WELDING SYMBOLS................................................................................. 263Introduction..............................................................................................................................263Objectives ................................................................................................................................264Types of Joints and Types of Welds ........................................................................................264Components of a Welding Symbol ..........................................................................................267Weld Symbols and Supplementary Symbols...........................................................................270Groove Welds ..........................................................................................................................271

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Partial Penetration Welds.........................................................................................................274Fillet Welds..............................................................................................................................276Combined Weld Symbols ........................................................................................................281Other Welding Symbol Conventions .......................................................................................281Plug and Slot Welds.................................................................................................................283Welding Symbol Summary......................................................................................................284References................................................................................................................................284Guides and Exercises ...............................................................................................................286Answers ...................................................................................................................................290

Chapter 9—WELDING INSTRUCTION.......................................................................... 293Introduction..............................................................................................................................293Quality Metric..........................................................................................................................293Cost Metric ..............................................................................................................................295Throughput Metric ...................................................................................................................295Safety Metric............................................................................................................................296Welding Procedures .................................................................................................................296Welder Qualification Test Record ...........................................................................................304Conclusion ...............................................................................................................................306Review Questions ....................................................................................................................307Answers ...................................................................................................................................308

Chapter 10—WELDING ECONOMICS AND VARIABLES............................................ 309Introduction..............................................................................................................................309Welding Productivity ...............................................................................................................310Do’s Goal 1: Reduce Weld Metal Volume..............................................................................311Do’s Goal 2: Reduce Arc Time Per Weldment .......................................................................323Do’s Goal 3: Reduce Rejects, Rework, and Scrap ..................................................................328Do’s Goal 4: Reduce Work Effort ...........................................................................................333Do’s Goal 5: Reduce Motion and Delay Time ........................................................................336Method for Computing Operating Factor ................................................................................340Putting It All together ..............................................................................................................342Conclusion ...............................................................................................................................347Summary of Key Concepts ......................................................................................................348Reference .................................................................................................................................349Review Questions ....................................................................................................................349Answers ...................................................................................................................................354

Chapter 11—APPLICATION OF WELDING STANDARDS........................................... 355Introduction..............................................................................................................................355Widely Used Standards and Codes ..........................................................................................355Qualification of Welding Procedures ......................................................................................359Qualification of Welders..........................................................................................................359Comparison of Common Standards .........................................................................................359Conclusion ...............................................................................................................................362

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Review Questions ....................................................................................................................363Answers ...................................................................................................................................364

Chapter 12—WELDING INSPECTION........................................................................... 365Welding Inspection ..................................................................................................................365Acceptance Criteria..................................................................................................................366Visual Discontinuities..............................................................................................................367Visual Inspection Method........................................................................................................373Liquid Penetrant Testing (PT) .................................................................................................379Magnetic Particle Testing (MT) ..............................................................................................381Ultrasonic Testing (UT)...........................................................................................................385Radiographic Testing...............................................................................................................389Conclusion ...............................................................................................................................392References................................................................................................................................393Review Questions ....................................................................................................................393Answers ...................................................................................................................................396

Chapter 13—WELDING HEALTH AND SAFETY.......................................................... 397Creating a Safe Workplace ......................................................................................................397The Importance of Training .....................................................................................................397Important References ...............................................................................................................398Hazards in the Shop and Construction.....................................................................................398Electrical Safety .......................................................................................................................399Arc Radiation...........................................................................................................................404Burns and Fire..........................................................................................................................404Fumes and Gases .....................................................................................................................407Gases Produced During Welding.............................................................................................413Working with Oxygen and Other Gases ..................................................................................413Cylinders ..................................................................................................................................415Working in Confined Space.....................................................................................................418Welding on Containers that Have Held Hazardous Materials .................................................419Reference .................................................................................................................................419Guides and Exercises ...............................................................................................................420Answers ...................................................................................................................................424

Chapter 14—WORK REPORTS AND RECORDS......................................................... 425Introduction..............................................................................................................................425Quality Metric..........................................................................................................................426Cost Metric ..............................................................................................................................426Conclusion ...............................................................................................................................432Review Questions ....................................................................................................................432Answers ...................................................................................................................................434

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AWS CWS Manual for Quality and Productivity ImprovementChapter 1—Management Systems for the Welding Supervisor

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Chapter 1—MANAGEMENT SYSTEMS FOR THE WELDING SUPERVISOR

Introduction In manufacturing and construction companies that use welding as a coreprocess, welding supervisors hold a unique position. To begin to understandthe welding supervisor and his duties, it is important to understand his uniqueposition.

Most companies have supervisors. They may be called team leaders or manag-ers, but their role is the same. A supervisor provides workers their assignments,makes sure they have the tools, materials, and training to do their work, pro-vides support, and monitors them throughout their work shift. The result ofeffective supervision is each worker is efficient and produces only qualitywork. With effective supervision, production workers achieve higher levels ofproductivity and quality.

With the day-to-day pressures of getting production out, how a supervisorshould function and the results expected are lost. In many production environ-ments, supervisors, including welding supervisors, are expediting parts, chas-ing paperwork, filling out unnecessary reports, and performing other non-supervisory duties, which take them outside of their assigned department. Thisleaves production workers unsupervised for long periods of time. This resultsin lack of communication and support, leaving welders with the feeling thatthey are on their own. Problems that they encounter must be handled with thehope that the results will be acceptable.

In many cases, welding supervisors have limited understanding of the technicalaspects of welding and, therefore, are unsure of their ability to provide direc-tion and support to the welders. This situation has unwittingly limited theamount of daily support the welder receives. Company management may notrealize the detrimental affect when welding supervisors are not properlytrained or assigned to perform essential duties, which can lead to improvedquality and productivity on each shift.

Any training course for welding supervisors should address a welding super-visor’s need both for technical and managerial training to develop the skills toperform his job in the most professional manner. This leads to improved resultsin both quality and productivity. This Certified Welding Supervisor Manual forQuality and Productivity Improvement recognizes that the welding supervisorhas an important role in the operations of any company that does welding.

To fully understand and appreciate his role, the supervisor must first under-stand some of the different management systems currently used by manufac-turing companies.

The management systems used by companies are numerous and varied. Tomaintain a manageable review of these systems, this manual will consider only