WCL Inspection & Quality Control 4 — Questions and Answers
Question 1: Which type of weld discontinuity is most detrimental to fatigue life?
- Porosity
- Slight undercut
- Cracks (Correct answer)
- Slight overlap
Correct answer: Cracks
Cracks are the most detrimental weld discontinuity for fatigue life because their sharp tips act as severe stress concentrators that propagate rapidly under cyclic loading.
Question 2: When a welder's qualification test is failed, AWS D1.1 requires the welder to:
- Wait 30 days before retesting
- Immediately retest without restriction
- Retest immediately or after practice with the right to retest twice more (Correct answer)
- Attend additional training before any retest is permitted
Correct answer: Retest immediately or after practice with the right to retest twice more
AWS D1.1 allows an immediate retest or retest after additional practice; if the second test also fails, additional practice and approval are required before a third attempt.
Question 3: What does 'discontinuity' mean in the context of weld inspection, as distinguished from a 'defect'?
- All discontinuities are automatically defects
- A discontinuity is a deviation from ideal; a defect is a discontinuity that exceeds acceptance criteria (Correct answer)
- Defects are surface-only while discontinuities are internal
- They are interchangeable terms in AWS standards
Correct answer: A discontinuity is a deviation from ideal; a defect is a discontinuity that exceeds acceptance criteria
A discontinuity is any interruption in the typical structure of a weld, while a defect is a discontinuity that exceeds the acceptance criteria of the applicable code and is therefore rejectable.
Question 4: Liquid penetrant testing (PT) is limited to detecting:
- Internal voids only
- Surface-breaking discontinuities only (Correct answer)
- Subsurface discontinuities within 1/4 inch
- Magnetic anomalies in the weld
Correct answer: Surface-breaking discontinuities only
Liquid penetrant testing can only detect discontinuities that are open to the surface because the penetrant must enter the defect by capillary action.
Question 5: What is the function of the 'Certified Welding Inspector' (CWI) designation issued by AWS?
- Authorizes the holder to write welding procedures
- Certifies the holder has the knowledge to inspect welds to code requirements (Correct answer)
- Qualifies the holder to perform all forms of NDT
- Licenses the holder to perform structural welding
Correct answer: Certifies the holder has the knowledge to inspect welds to code requirements
The AWS CWI credential certifies that the individual has demonstrated the knowledge and skills required to inspect welds in accordance with applicable codes and standards.
Question 6: In welding, what is 'overlap' (cold lap)?
- Weld metal that protrudes beyond the weld toe without fusing to the base metal (Correct answer)
- Incomplete penetration at the root pass
- A crack running parallel to the fusion line
- Porosity visible on the weld face
Correct answer: Weld metal that protrudes beyond the weld toe without fusing to the base metal
Overlap is weld metal that extends beyond the weld toe or root and lies on the base metal surface without fusing to it, creating a mechanical notch.
Question 7: Which element in the weld environment most commonly causes hydrogen-induced cracking?
- Oxygen from atmospheric exposure
- Moisture in consumables or on base metal (Correct answer)
- Nitrogen from shielding gas contamination
- Carbon from electrode coating
Correct answer: Moisture in consumables or on base metal
Moisture (H₂O) is the primary source of hydrogen in welding; it decomposes in the arc and allows atomic hydrogen to diffuse into the weld metal, causing cracking.
WCL Inspection & Quality Control 4
Which type of weld discontinuity is most detrimental to fatigue life?