If not welder qualification, it might be qualification of the welding procedure. I imagine welding in a warm workshop is not the same as welding an oil pipeline in Arctic temperatures ...

welding performance qualification - The demonstration of a welder's ability to produce welds meeting prescribed standards.

welder certification - Written verification that a welder has produced welds meeting a prescribed standard of welder performance.

welding procedure specification (WPS) - A document providing the required welding variables for a specific applicaiton to ensure repeatability by properly trained welders and welding operators.

welding procedure qualification record (WPQR) - A record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualify a welding procedure specification.

[Standard Welding Terms and Definitions, American Welding Society]

IOW, for special projects, it is not just a matter of taking a given welding procedure and applying it to your job (which might have steel with different alloys, of different thicknesses, with different angles where parts meet, etc.). So it has to be proved that the procedure proposed not only works but can effectively be reliably repeated by trained/qualified welders. I think it likely that the French could refer to this operation as "qualification" (of the proposed welding procedure).

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Note added at 1 day16 mins (2006-08-27 23:01:22 GMT)
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Actually I think it means that the technical department prepares the parts and equipment and/or makes same available for site testing ("qualification", if the test is passed) of the proposed welding procedure/specification.

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Note added at 2 days23 hrs (2006-08-29 22:04:18 GMT)
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Some time later: The job I am currently doing, on steel fabrication, refers to "Qualification de soudage" for which a "Procès-verbal de qualification des modes opératoires de soudage" is generated. The second part is obviously the WPQR referred to above. This would appear to clinch it.