Qualifying a Procedure for a New Thickness Range
A shop has a qualified GMAW procedure tested on 10 mm plate in the flat position with 1.2 mm solid wire and a 75% argon/25% CO2 blend. A new contract requires 4 mm fillet welds in the horizontal position on the same material group, plus some 20 mm groove welds in the vertical-up position. The welding coordinator wants to use the existing procedure for everything to avoid requalification cost and delay. The customer's specification requires procedure qualification and welder performance qualification before production. The shop has a certified welder who has never welded the 20 mm vertical-up joint.
1. Evaluate whether the existing procedure covers the new work, and identify which variables trigger requalification.
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The existing procedure was qualified on 10 mm plate in the flat position. Essential variables typically include base metal thickness range, position, and sometimes transfer mode and gas. A procedure qualified on 10 mm does not automatically extend to 4 mm or to 20 mm; many codes set qualified thickness ranges around the test thickness, and going well below or above it requires a new test. Position is also essential: flat-position qualification generally does not cover vertical-up. The 4 mm fillet and the 20 mm vertical-up groove are therefore outside the qualified envelope unless the code's specific ranges say otherwise. The correct step is to check the applicable code's essential variable table, then qualify additional procedures or revise the existing one with new tests covering the required thicknesses and positions.
2. The certified welder has never welded the 20 mm vertical-up joint. What must happen before that welder produces the contract work?
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The welder must be qualified by test for the joint type, position, and thickness involved. A welder who is certified for other work is not automatically qualified for vertical-up groove welding on 20 mm plate. Arrange welder performance qualification on a test coupon matching the essential conditions, have it inspected and tested per the code, and record the results. Provide practice time before the test, since the welder has no experience with that configuration. Only after the welder's qualification is documented should production begin, and the shop should keep the qualification records available for the customer's review.