WPS Coverage for Thicker Plate in 3G
A shop has a WPS qualified by a PQR made on 9.5 mm (3/8 in) ASTM A36 plate, single-V groove, SMAW with E7018, 1G position, root gap 3 mm, and a qualified thickness range of 3 mm to 19 mm in the WPS. The WPS also lists 'all positions' in the position block. Production now requires a 25 mm (1 in) thick A36 bracket in the 3G position, welded with the same electrode and joint design. The production manager says the WPS is valid because the electrode and process are the same and the WPS says 'all positions.' The welder has not welded 3G in 8 months. The project code is AWS D1.1. The PQR is signed and complete. The shop's WPS is posted at the bay and the welder has a current card for 1G only.
1. Is the existing WPS sufficient for the 25 mm, 3G production weld? Give your reasoning.
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No. The PQR was made on 9.5 mm plate and the WPS itself limits thickness to 19 mm, so 25 mm is outside both the tested thickness and the written range. Thickness is an essential variable for procedure qualification; a 9.5 mm test does not qualify 25 mm unless the code's thickness multiplier or a prequalified WPS covers it. The PQR was run in 1G, but the WPS says 'all positions.' Position is also essential. A 1G test does not qualify 3G unless the code specifically permits it. The production manager's argument that the electrode and process are the same ignores both thickness and position. The welder's 8-month gap in 3G is a separate qualification issue.
2. Which essential variables are affected, and what records should be checked?
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Check thickness (base metal and deposited weld metal), position, electrode classification and brand, joint design, root spacing, preheat/interpass, and any backing or root treatment. For SMAW, electrode classification is essential, but a change from E7018 to another E7018 may still require verification of brand/lot if the code treats it as essential. The PQR should show the actual test thickness, position, and mechanical test results. The WPS should list a thickness range supported by the PQR, not an arbitrary 19 mm. The welder's qualification records must show current 3G coverage for the process and thickness.
3. What should be done before production welding begins?
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Qualify a new PQR on 25 mm plate in the 3G position with the production joint design and electrode, or use an existing PQR that already covers 25 mm and 3G. Revise the WPS to match the supported ranges and essential variables. Qualify or re-qualify the welder in 3G for the thickness involved. Do not start production on the bracket until the WPS and welder qualification are in place. If the project allows prequalified WPS under AWS D1.1, verify that all prequalification conditions-joint detail, thickness, position, electrode, and preheat-are met; otherwise, qualification testing is required.