NDT Weld Inspection & Evaluation 1 — Questions and Answers
Question 1: Which weld discontinuity is characterized by an unfused area between the weld metal and base metal along the weld toe?
- Porosity
- Lack of fusion (Correct answer)
- Undercut
- Overlap
Correct answer: Lack of fusion
Lack of fusion occurs when the weld metal fails to fuse completely with the base metal or adjacent weld passes, creating a planar discontinuity at the weld toe or between passes.
Question 2: According to AWS D1.1, which visual weld inspection criterion applies to undercut in a statically loaded structure?
- Undercut shall not exceed 1/32 inch in depth
- Undercut shall not exceed 1/16 inch in depth (Correct answer)
- Undercut is acceptable up to 1/8 inch in depth
- Undercut must be completely absent
Correct answer: Undercut shall not exceed 1/16 inch in depth
AWS D1.1 permits undercut up to 1/16 inch (1.6 mm) in depth for statically loaded structures, while cyclically loaded structures have stricter limits.
Question 3: What is the primary purpose of a weld profile gauge during visual inspection?
- Measuring weld preheat temperature
- Verifying weld bead geometry and throat dimensions (Correct answer)
- Detecting subsurface porosity
- Checking base metal hardness
Correct answer: Verifying weld bead geometry and throat dimensions
A weld profile gauge is used to measure weld geometry parameters such as fillet weld leg size, convexity, concavity, and throat dimensions to confirm they meet specification requirements.
Question 4: Which type of weld crack propagates parallel to the weld axis along the centerline of the weld bead?
- Transverse crack
- Underbead crack
- Longitudinal crack (Correct answer)
- Toe crack
Correct answer: Longitudinal crack
Longitudinal cracks run parallel to the weld axis and can occur in the weld metal or heat-affected zone, often caused by high restraint or improper bead-to-bead ratios.
Question 5: In a butt weld inspection, what does the term 'reinforcement' refer to?
- Backing bar used during welding
- Weld metal extending above the base metal surface (Correct answer)
- Filler material added to strengthen the joint
- Post-weld heat treatment process
Correct answer: Weld metal extending above the base metal surface
Weld reinforcement is the extra weld metal deposited above the plane of the base metal surface; codes limit its maximum height to prevent stress concentrations.
Question 6: What type of discontinuity appears as a group of small, rounded indications scattered throughout the weld metal?
- Slag inclusions
- Distributed porosity (Correct answer)
- Linear cracks
- Lack of penetration
Correct answer: Distributed porosity
Distributed porosity consists of multiple small, rounded gas pockets scattered throughout the weld metal, typically caused by contamination or improper shielding during welding.
Question 7: When performing visual inspection of a completed weld, which condition requires the inspector to reject the weld regardless of the applicable code?
- Acceptable weld reinforcement height
- Visible cracks of any length (Correct answer)
- Slight surface ripple in the weld bead
- Minor spatter within 1 inch of the weld
Correct answer: Visible cracks of any length
Cracks of any length and orientation are universally rejectable discontinuities under all major welding codes because they propagate under service loads and can lead to catastrophic failure.
NDT Weld Inspection & Evaluation 1
Which weld discontinuity is characterized by an unfused area between the weld metal and base metal along the weld toe?