Level B visual acceptance on a 10 mm butt weld: undercut, cap height and missing identification
A 10 mm S355 plate butt weld, single-V, GMAW, is made in a workshop. The drawing note reads: "all welds 100% visual, acceptance ISO 5817 level B". The inspector finds: (a) undercut along the upper toe, continuous for 180 mm, measured depth 0.9 mm, sharp-edged; (b) cap height 3.0 mm above the parent surface, with a weld width of 9 mm; (c) scattered spatter on the parent plate beside the weld; (d) no welder's stamp on the joint, although the welder says he made it. The inspector has a calibrated weld gauge, a magnifier, the WPS and the drawing. The supervisor says "undercut of 1 mm is allowed in level C, so we are fine", and asks for the weld to be accepted so the section can be painted.
1. Assess findings (a) and (b) against level B and state the compliance decision, showing how the limits are derived.
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Undercut (a). For level B, the permitted undercut depth for a butt weld is 0.05t with an absolute cap of 0.5 mm. With t = 10 mm, 0.05t = 0.5 mm, so the limit is 0.5 mm. The measured 0.9 mm, continuous over 180 mm and sharp-edged, exceeds level B. It would sit within level C (0.1t = 1.0 mm) if the profile were acceptable - which is exactly the supervisor's argument - but the drawing specifies level B, so level C limits are irrelevant to acceptance. The sharp, continuous profile also concentrates stress and is a crack initiator on any cyclically loaded member; that should be stated in the report.
Cap height (b). For butt welds, the level B excess weld metal limit is h ≤ 1 mm + 0.1b, with b the weld width and an absolute maximum of 5 mm. With b = 9 mm, the limit is 1 + 0.9 = 1.9 mm. The measured 3.0 mm exceeds level B. It also exceeds level C (1 + 0.2 × 9 = 2.8 mm) and would only fall within level D (1 + 0.25 × 9 ≈ 3.25 mm). Exact values must be read from the current edition of the table for the joint type, but the conclusion is the same.
Decision: the weld is nonconforming to the drawing. Disposition is repair (dressing the cap and re-profiling the undercut toe to a smooth transition, as permitted by the standard and agreed by the responsible person), then re-inspection.
2. How do you handle findings (c) and (d)? What can and cannot be concluded from a visual inspection?
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Spatter (c). ISO 5817 treats surface condition and spatter under surface irregularities, and level B is demanding. In practice most specifications also require spatter to be removed because it can mask undercut, retain moisture and interfere with coating. Action: require removal and re-inspection of the cleaned surfaces, and record it; at minimum it is an observation, and if the applicable table or contract prohibits it, a nonconformity.
Missing stamp (d). This is a traceability nonconformity under ISO 3834-2 and EN 1090-2, not a weld defect. The joint cannot be attributed to a qualified welder. The inspector cannot accept it on the welder's word. Either the joint is identified through production records, shift lists and a controlled statement from the welder, countersigned, or it is treated as unidentified and referred to the responsible person, who may require additional inspection. Record it as a nonconformity either way.
What visual inspection cannot do: it cannot confirm root penetration, fusion, internal porosity, or crack depth. A visual acceptance is a statement about what is visible on the surface only. If the inspection plan requires NDT, visual acceptance does not replace it, and the inspector must not imply that it does.
3. List the essential content of your visual inspection report and explain how the nonconformances and the disposition should be recorded.
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A defensible report contains: project and report number; drawing, joint and weld identification; material, grade and thickness; WPS number and welding process; welder identification (or a statement that it is missing); date and stage of inspection (before, during, after welding); the applicable standard and acceptance level (here ISO 5817 level B, as called up by the drawing); the instruments used, with calibration status (weld gauge, magnifier); environmental conditions if relevant.
Findings must be stated with measured values and locations: undercut 0.9 mm deep, continuous 180 mm, upper toe, sharp-edged; cap height 3.0 mm with 9 mm width; spatter on parent plate adjacent to the weld; welder's stamp absent. Each finding is compared with the specific limit from the table and marked pass or fail.
Conclusion: nonconforming, with the specific clauses. Disposition: repair and re-inspect - dressing the cap and re-profiling the toe - with the repair procedure approved by the responsible person and the repaired area re-examined visually and, if the plan requires, by surface NDT. Note clearly that a concession to accept as-is can only be granted by the responsible designer, not by the inspector or the supervisor, and record the client notification. Sign and date the report, reference any photographs or sketches, and attach them to the inspection record.