Position Coverage for a Pipe Welder
A welder qualifies on a pipe test piece, process 141, material group 1, outside diameter 60.3 mm, wall thickness 5 mm, welded in the fixed horizontal (PC) position with the pipe axis horizontal and the weld made around the circumference without rotating the pipe. All tests pass. Production now needs this welder for: (a) the same pipe size welded in the fixed vertical (PF) position (pipe axis vertical, welding upwards), and (b) a 114 mm outside diameter pipe of the same wall thickness welded in the PC position. The welding coordinator wants to know whether the single PC qualification covers both jobs, and what the diameter range is.
1. Does the PC (fixed horizontal) pipe qualification cover the PF (fixed vertical) production weld?
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No. Position qualification is specific: PC and PF are different positions, and a qualification in one does not automatically extend to the other. The PC test demonstrates competence welding around a horizontal fixed pipe, where gravity acts differently on the molten pool than in the vertical-up progression of PF. The welder needs a separate PF test (or a test in a position that the standard expressly treats as covering PF) before doing job (a).
The common mistake is to assume 'pipe position' is one qualification; EN ISO 9606-1 treats each position separately on the certificate.
2. Does the 60.3 mm PC qualification cover the 114 mm PC production pipe? What is the qualified outside-diameter range?
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For pipe, the qualified outside-diameter range is generally from the test diameter upwards (the test piece sets the minimum), subject to the standard's rules; a smaller-diameter test does not qualify larger diameters beyond the stated range, and a larger test does not qualify smaller ones below the limit. With a 60.3 mm test piece, the qualification covers 60.3 mm and above for the same position, process, material group and thickness - so the 114 mm PC pipe (job b) is covered, provided wall thickness and other essential variables also match.
The certificate must state the diameter explicitly (e.g. 'OD ≥ 60.3 mm') so the production planner can check it.
3. Set out the certificate entries and the action for each job.
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| Job | Position | Diameter | Covered by PC 60.3 test? | Action |
|---|---|---|---|---|
| (a) | PF | 60.3 mm | No - different position | PF test required |
| (b) | PC | 114 mm | Yes - ≥ 60.3 mm, same position | Proceed |
Certificate entry: 141, group 1, pipe, PC, OD ≥ 60.3 mm, t = 5 mm (state qualified thickness range); PF: not qualified. The lesson: position and diameter are independent essential variables, and each must be checked separately against the certificate.