Welding Discontinuities Quiz-Easy-12Questions CWB

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Questions and Answers

What should be done upon receipt of material to ensure its quality?

Immediately start the cutting and preparation process

Request a Mill Certificate for the material

Assume the material is of good quality without inspection

Inspect the material to ensure its condition is acceptable and it is the proper type and grade (correct)

What is overlap in welding and how is it corrected?

Overlap is a type of weld discontinuity, and it is corrected by using different welding electrodes

Overlap is an excess of weld metal at the toe of a weld, and it is corrected by grinding and blending (correct)

Overlap is a type of welding technique, and it is corrected by adjusting the welding parameters

Overlap is a desired feature in welding, and it is left as is without any correction

What are some probable causes of overlap in welding?

Operator technique, electrode size, welding parameters, and surface contaminants (correct)

Material type, welding environment, welding machine brand, and electrode color

Welding temperature, parent metal type, welding speed, and weld thickness

Material hardness, welding current, welding voltage, and welding angle

What is the maximum distance defined as concavity in a fillet weld?

The distance from the face of a concave fillet weld to a line joining the weld toes Signup and view all the answers

What can cause incomplete fusion in welding?

Improper electrode selection, welding parameters, and joint design Signup and view all the answers

How are out-of-line weld beads corrected?

By removing the weld from one side by grinding or gouging and depositing a new weld Signup and view all the answers

What is the primary cause of solidification cracking in welds?

Contraction strains during solidification Signup and view all the answers

Under what conditions does hydrogen-induced cold cracking occur?

Low temperatures and presence of hydrogen in the weld microstructure Signup and view all the answers

What factor increases the risk of solidification cracking?

Greater depth of the weld deposit compared to its width Signup and view all the answers

What are the primary causes of solidification cracking in welds?

Contraction strains and rejection of alloying elements Signup and view all the answers

When does hydrogen-induced cold cracking occur?

Hours, days, weeks, or even months after welding Signup and view all the answers

What factors must be present for hydrogen-induced cracking to occur?

Susceptibility to hydrogen embrittlement, hydrogen content, stress, and low temperature Signup and view all the answers

What is the primary concern when repairing a crack in a weld or base metal?

Ensuring the crack is completely removed Signup and view all the answers

What may result in lack of corrosion resistance in weldments?

Incorrect weld metal composition Signup and view all the answers

When should nondestructive examination be conducted after completion of the welds?

Not less than 48 hours after completion Signup and view all the answers

What is the primary purpose of nondestructive testing after repairing a crack in a weld or base metal?

To ensure that the crack is completely removed and the repair is successful Signup and view all the answers

What is considered a defect in a weld or base metal?

Cracks, lack of fusion, or overlap Signup and view all the answers

What is the recommended time frame for conducting nondestructive examination after completion of the welds?

Not less than 48 hours Signup and view all the answers

Study Notes

Welding Defects and Corrective Measures

Prior knowledge of code and procedure requirements is crucial for informed decisions on cutting and preparation methods.
Material inspection upon receipt is essential to ensure proper type, grade, and acceptable condition.
Requesting Mill Certificates for ordered material helps in verifying the type and grade received.
Machinists aware of required tolerances are more likely to adhere to requirements and identify problems early in material preparation.
Overlap is an excess of weld metal at the toe of a weld, causing stress concentration and masking incomplete fusion.
Probable causes of overlap include operator technique, electrode size, welding parameters, and surface contaminants.
Proper welding procedures and techniques should prevent overlap, and if it occurs, grinding and blending can correct it.
Magnetic particle testing (MT) is recommended after overlap repair to ensure complete removal and detect hidden overlap.
Convexity is the maximum distance from the face of a convex fillet weld perpendicular to a line joining the weld toes.
Excessive convexity in single pass fillet welds adds stress risers, while in multipass welds, it may lead to other discontinuities.
Probable causes of convexity are operator technique, electrode size, welding parameters, and surface contaminants.
Excessive weld reinforcement stiffens the section, establishes notches, and increases weight in groove welds. Proper welding procedures and techniques should prevent excessive weld reinforcement.

Weld Discontinuities and Defects in Welding Processes

Large diameter pipes can be repaired using the same method as external undercut, while small diameter pipes with undercut defects require cutting out the section and preparing a new joint.
Acceptable and unacceptable groove weld profiles are shown in Figure 19, with specific criteria for reinforcement, underfill, excessive weld reinforcement, undercut, and overlap.
Concavity in welds is defined as the maximum distance from the face of a concave fillet weld to a line joining the weld toes, and excessive concavity can occur with fillet welds.
Causes of concavity in welds include operator technique, welding parameters, and position of welding, and excessively concave welds can give a deceptive appearance of the actual weld size.
Desirable, acceptable, and unacceptable fillet weld profiles are shown in Figure 23, with specific criteria for convexity, excessive undercut, overlap, and insufficient leg.
Weld deficiencies due to insufficient or excessive size and poor profile may be detected by visual examination or by using suitable gauges.
The leg and throat size of concave fillet welds can be measured with fillet weld gauges, and only the leg size of convex fillet welds can be measured with fillet weld gauges.
Misalignment of the weld due to insufficient care in positioning automatic welding machines, incorrect bead placement, incorrect edge preparation, or inaccurate backgouging can lead to out-of-line weld beads.
Out-of-line weld beads can result in incomplete joint penetration when complete joint penetration is required, and correction requires the removal of the weld from one side by grinding or gouging and the depositing of a new weld.
Incomplete fusion is the failure to fuse between weld metal and fusion faces or adjoining weld beads, and it may occur at any point in the welding groove or fillet weld.
Incomplete fusion may be caused by factors such as improper electrode selection, welding parameters, manipulation of the electrode, cleaning of material, joint design, and poor joint preparation and fit-up.
Improper joint design, poor joint preparation, and fit-up can inhibit electrode manipulation and affect the welding process.

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Test your knowledge of welding discontinuities with this quiz. Identify and understand terms such as slag and slag inclusion, and enhance your understanding of welding processes.