Fillet Weld Size Dispute on a D1.1 Skid Frame
A fabricator is building a welded structural-steel skid to AWS D1.1. The EOR's drawings call out a 6 mm (1/4 in) fillet on a T-joint between a 12 mm plate and a 20 mm plate, both ASTM A36. During a surveillance visit the CWI measures several welds at 5.0–5.5 mm leg on the 12 mm side and finds one 25 mm length of undersized weld adjacent to a weld crater. The fabricator argues that the joint is 'statically loaded' and that D1.1 tolerance allows undersize. The CWI must decide whether to accept, repair, or reject, and how to document the disposition. The fabricator also asks whether they can simply add a cover pass.
1. How should the CWI evaluate the undersize fillet against D1.1 acceptance criteria, and what is the correct disposition?
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D1.1 treats fillet weld size as a workmanship acceptance item. The specified size is 6 mm; undersize is permitted only within the code's stated tolerance for the weld size, and a continuous undersize run beyond that tolerance is a rejectable discontinuity. The CWI should:
- Confirm the specified size from the drawing and the applicable D1.1 edition invoked by the contract.
- Measure leg size with a proper fillet gauge at multiple points along the weld, not just at the worst spot.
- Determine whether the undersize is isolated (a short length) or extends over a significant portion of the weld.
- If the undersize exceeds the code tolerance, issue a nonconformance and require repair.
A cover pass is not automatically acceptable: adding weld metal over an undersized fillet can restore size, but the fabricator must show the resulting profile meets the specified size and that no slag or lack of fusion is trapped. The CWI should require the repair to be made per an approved WPS, re-inspected, and documented on the inspection report with location, measured size, and disposition.
2. The fabricator claims static loading exempts the weld from size requirements. Evaluate that claim.
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The claim is incorrect as stated. D1.1's fillet weld size requirements are tied to the design and to the code's workmanship provisions, not to a blanket 'static loading' exemption. Static versus cyclic loading affects fatigue provisions and certain detailing rules, but it does not erase the specified weld size or the acceptance criteria for undersize.
The CWI should point the fabricator to the contract documents: the EOR specified 6 mm; the fabricator must meet it unless the EOR approves a change. If the fabricator believes the size is over-specified, the correct path is a formal RFI to the EOR, not unilateral field reduction. The CWI's role is to verify conformance to the approved drawings and D1.1, and to document any deviation.
3. What records should the CWI require before closing the nonconformance?
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The CWI should require: (1) a repair WPS qualified per D1.1 and any required PQR; (2) welder qualification records for the repair welder; (3) the NCR number, location sketch, and measured pre-repair sizes; (4) post-repair inspection results (visual plus any required MT/PT per the contract); (5) the final disposition signed by the CWI and accepted by the EOR if a design change was involved; and (6) updated as-built drawings or weld maps. The record should state the code edition, acceptance criterion applied, and the objective evidence (measurements) supporting closure.