§3.1D · Under Visual examination
Discontinuity or defect? Only the acceptance criteria decide
A weld discontinuity is any interruption in the normal structure of the weld or base metal. A defect is a discontinuity that fails the acceptance criteria you're inspecting to. Every defect is a discontinuity; plenty of discontinuities never become defects.
- Exam
- CWI
- Clause
- §3.1D
- Tags here
- 8
- Parent
- Visual examination
3.1D.1Same flaw, two verdicts
Take a short slag inclusion found on a radiograph. Under one code, one loading and one thickness, it passes. Put the same slag in a cyclically loaded member, or under a code with tighter limits, and it's rejectable. The slag didn't change. The criteria did.
So a CWI calls it an indication or a discontinuity until it's been sized, and calls it a defect only after comparing it against the criteria. On the floor that decides what goes on your report. On the exam it decides tags that hinge on the word.
Where the criteria come from
The contract names the code and its edition, and the code sets the limits. On D1.1 work the inspection criteria sit in Clause 8 of both the 2020 and the 2025 editions, split by statically and cyclically loaded connections, with extra rules for tubulars. Clause 8 also lets the Engineer approve alternate acceptance criteria. AWS lists both D1.1 editions for Part C; the Part C code book page has the details.
Flaw, the in-between word
A3.0, the source of the terms and definitions clause, also defines a flaw: an undesirable discontinuity, short of a ruling on rejectability. The vocabulary shows up in the exam spec too. B5.1:2025 renamed the biggest Part B domain from "Welding Inspection and Flaws" to "Welding Inspection and Discontinuities", at least 34% of Part B (AWS B5.1:2025, Table 8.1, checked October 2026).
3.1D.2Common weld discontinuities
| Discontinuity | Where it sits | Usually found by | Read more |
|---|---|---|---|
| Porosity | Weld metal | VT if surface-breaking; RT | Porosity |
| Undercut | Base metal at the toe | VT and a depth gauge | Undercut vs overlap |
| Overlap (cold lap) | Weld metal past the toe | VT | Overlap and underfill |
| Incomplete fusion | Bevel faces, between beads | UT; RT when lined up | Incomplete fusion vs penetration |
| Slag inclusion | Between passes | RT | RT vs UT |
| Cracks | Weld, heat-affected zone, craters | VT, PT, MT, UT | Hot vs cold cracking |
| Undersized fillet | Weld profile | Fillet gauge | Fillet size vs throat |
| Lamination | Base metal, from the mill | UT | NDE methods |
3.1D.3Before you write reject
- The governing code and edition, taken from the job documents
- Loading: statically or cyclically loaded, tubular or nontubular
- Weld type and size the drawing calls for
- The indication sized with the right gauge, at its worst point
- Its location measured from a datum, with the length affected
- A nonconformance written up per the job's procedure; relaxing criteria is the Engineer's call under D1.1
- Final acceptance by a CWI or SCWI; a CAWI can't give it (AWS QC1:2016-AMD1, clause 4.4, checked October 2026). More in inspector duties
3.1D.4Is it a defect yet?
Floor calls and definitions, with the acceptance criteria always in the background.
0 of 8 tagged · 0 accepted
Tag 01
Which of these is NOT a weld discontinuity?
Remarks on every option
- A Correct: Surface rust is oxidation on the material, not a discontinuity in the weld. You clean it off before welding; weld acceptance criteria don't judge it.
- B Porosity is a weld discontinuity. It becomes a defect only when it fails the acceptance criteria.
- C Slag inclusion is a weld discontinuity: nonmetallic solid trapped in the weld. It's rejectable only beyond the criteria.
- D Undercut is a weld discontinuity at the toe or root. The code's limit decides whether it's a defect.
Pick an option. The remarks on all 4 open here.
Tag 02
Which of the following is not a legitimate acceptance standard for a typical groove weld? Review the inspection criteria for joint defects.
Remarks on every option
- A Undersize welds are judged against the acceptance criteria. Wrong size is a real rejection basis.
- B Excess root penetration is limited by the acceptance criteria.
- C Correct: Looks alone aren't an acceptance criterion. Welds are judged on measurable discontinuities and dimensions, not on how pretty they look.
- D Lack of fusion is a standard rejectable condition.
Pick an option. The remarks on all 4 open here.
Tag 03
Which term describes the written document that specifies acceptable weld quality levels?
Remarks on every option
- A Correct: Acceptance criteria are the written limits that decide which discontinuities are acceptable, usually from the governing code or contract.
- B "Pass requirements" isn't the standard term.
- C "Quality standards" is too broad. The specific term for acceptable quality limits is acceptance criteria.
- D "Approval guide" isn't a standard term.
Pick an option. The remarks on all 4 open here.
Tag 04
How should an inspector respond when finding a questionable discontinuity?
Remarks on every option
- A Size is decided by measuring against the criteria, not by eye. Small ones still get recorded and evaluated.
- B The welder made the weld. Acceptance comes from the criteria, not the welder's opinion.
- C A discontinuity isn't a defect until it fails the criteria. Rejecting without checking is the wrong call.
- D Correct: Record it, size it, and compare it with the acceptance criteria. Only then decide whether it's a defect.
Pick an option. The remarks on all 4 open here.
Tag 05
Which condition requires immediate rejection of a weld during visual inspection?
Remarks on every option
- A Correct: D1.1 visual criteria reject any crack regardless of size, and a through-thickness crack is about as serious as it gets.
- B Slight discoloration isn't a rejectable discontinuity on structural steel.
- C A little spatter is usually a cleanup item, not a rejection.
- D Minor surface roughness is cosmetic and usually acceptable.
Pick an option. The remarks on all 4 open here.
Tag 06
When evaluating a weld for acceptance, what should be considered first?
Remarks on every option
- A Size gets checked, but only after you know which requirements apply.
- B Surface condition is judged against criteria that come from the contract documents.
- C Correct: Contract documents set the governing code, edition and acceptance criteria. Know those before judging anything on the weld.
- D Looks alone can't decide acceptance. You need the contract's criteria first.
Pick an option. The remarks on all 4 open here.
Tag 07
You find undercut along a fillet weld toe. Your helper says, "Undercut, so the weld is defective." What's the right reply?
Remarks on every option
- A Undercut is a discontinuity type. A3.0 keeps the word defect for a discontinuity that fails the acceptance criteria, so the name alone decides nothing.
- B Correct: The name never decides it. You size the undercut, check it against the code's limit for the job, and only a failing result makes it a defect.
- C Being measurable just means you can size it. The size then goes against the code's limit; only a reading over that limit makes it a defect.
- D Loading type changes which undercut limit applies, not the rule. Undercut on statically loaded work can be rejectable too.
Pick an option. The remarks on all 4 open here.
Tag 08
You're inspecting a weld to its governing code. Which of these findings is a defect?
Remarks on every option
- A Deeper than the shop's target is a workmanship call. While it stays inside the code limit for the loading, it's a discontinuity, not a defect.
- B Being the biggest pore on the weld doesn't matter. If its size is within the code's limit, it's an acceptable discontinuity.
- C Comparing joints isn't the test. Convexity inside the profile the code allows is acceptable, whatever the last joint looked like.
- D Correct: A defect can come from accumulated effect. Pores that pass one at a time become a defect when their combined size goes over the code's limit.
Pick an option. The remarks on all 4 open here.
3.1D.5When the word defect comes up
Are weld defects and weld discontinuities the same thing?
No. A discontinuity is any interruption in the material. It becomes a defect only when it fails the acceptance criteria for that job.
Is cold lap a defect?
Cold lap is shop slang for overlap. D1.1's weld profile requirements treat overlap as an unacceptable profile, so on D1.1 work it gets written up and repaired.
What are the common types of weld defects?
The usual list: porosity, undercut, overlap, incomplete fusion, incomplete joint penetration, slag inclusions, cracks, and wrong size or profile. Each is a discontinuity first. The visual examination clause covers how they're judged.
Can a weld with a defect stay in service?
Under D1.1 the Engineer can approve alternate acceptance criteria (Clause 8). The inspector reports what was found and doesn't relax the criteria on the spot.
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