Welding Principles

Table of Contents

Chapter 1: Fundamentals of Welding

Topics: Metals; Common and production welding processes; Kinds of welds and welded joints; Weld parts; Fusion; Penetration; Joint design and fitup

Learning Objectives:

• Describe fusion welding, resistance welding, filler rods, and electrodes.
• Compare the oxyfuel and arc welding processes and compare the SMAW, GMAW, and GTAW processes.
• Describe and sketch the following kinds of joints-butt, lap, tee, corner, and edge.
• Describe the following kinds of welds-groove, fillet, plug, slot, spot, and seam.
• Name and locate the parts of a weld.
• Discuss basic considerations in joint design and fitup.

Chapter 2: Welding Safety

Topics: Fire and explosion hazards; Burns; Fumes and gases; Respiratory, eye, face, and hearing protection; Protective clothing; Handling cylinders; Shock

Learning Objectives:

• Explain the importance of good housekeeping in an area where welding is taking place.
• List at least three precautions to take to avoid fires and explosions when welding.
• Describe two methods of protecting yourself against the fumes and gases associated with welding.
• Describe the personal protective equipment required when welding.
• Explain the precautions to take when using and handling cylinders and regulators.

Chapter 3: Oxyfuel Welding Equipment

Topics: Gas pressure regulators; Check valves; Hoses, torches, and tips; Filler rods; Protective gear; Preparing to weld; Making the weld; Shutdown

Learning Objectives:

• Briefly describe the oxyfuel welding process and the components of an oxyfuel welding outfit, including the lighting device.
• Discuss safety precautions and personal protective gear required for working with oxyfuel equipment.
• List the steps involved in preparing to weld.
• Compare the neutral, carburizing, and oxidizing flames.
• List the steps in safely shutting down an oxyfuel welding system.

Chapter 4: Arc Welding Equipment

Topics: Welding with electricity; Constant current, voltage power sources; Welding machines, cables, electrodes, and electrode holders; Safety

Learning Objectives:

• List similarities and dissimilarities between oxyfuel welding and arc welding.
• Describe the electric welding circuit, including choice of ac or dc, dc polarity, and power sources.
• Discuss welding machine ratings in terms of amperage and duty cycle and describe features and uses of transformer, generator, rectifier, and inverter welding machines.
• Discuss welding cable considerations and describe the electrodes and electrode holders used for SMAW, GMAW, and GTAW processes.
• Discuss the personal safety gear and precautions necessary for arc welding and explain how arc welding accessories are used.

Chapter 5: Welding Techniques

Topics: Selecting a process; Welding positions; Oxyfuel, SMAW, GMAW, and GTAW procedures

Learning Objectives:

• Explain what considerations affect the selection of a welding process.
• Describe the four welding positions.
• Explain why overhead welds are difficult to make and tell how to make them.
• Describe the preparation required for oxyfuel welding, SMAW, GMAW, and GTAW processes.
• Describe the procedures involved in oxyfuel welding, SMAW, GMAW, and GTAW processes.

Chapter 6: Avoiding Weld Faults

Topics: Common weld problems; Poor fitup; Shape problems; Internal defects; Effects of heat; Expansion and contraction; Identifying metals

Learning Objectives:

• Describe the effects of electrode selection, current, arc length, and travel speed on arc welding procedures.
• Describe common causes of arc blow, a hard-to-start arc, and spatter, and explain why proper fitup is important.
• Define the terms overlap, undercut, blowhole, and inclusion and explain the causes of each.
• Explain how expansion and contraction can be controlled when welding.
• Name and describe the various tests used to identify metals.

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