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Essential variable . PQR

Essential variable . PQR

Essential variable . PQR

thread178-327928: PQR Essential Variable Changes Requiring WPS

I know this thread is closed but I have a question regarding this. From ASME 9 if you need to qualify a PQR for a certain weld setup this can be done on a piece of plate ( taking in consideration the plate thickness material etc }in the G1 position. This is to qualify all the essential Mechanical and metallurgical requirements of this new weld vs Parent metal. This is impact tensile hardness etc. All done with the weld welded in the G1 {flat down hand ). When it is about the position of the site weld or shop weld this is something to do with the welder skill proven to the WPS essential variable. He welds a 6 G test piece to the approved PQR drafted WPS . one and one if the Position is an Supplementary essential variable required for a certain Weld method or specific metallurgical or mechanical properties then the PQR test piece/s needs to be done say in the 2g and 4 g position etc.

Position is a welder skill essential variable only.

Anything that when changes that may have an effect on the metallurgical and mechanical properties (essential variable's would require a Requalification of the PQR.

RE: Essential variable . PQR

Impact test qualification on 1G plate does not qualify all welding positions. Vertical up progression does. Under ASME IX, WPS qualification assures meeting mechanical properties of the base materials, not corrosion properties. There is nothing to stop one from also requiring corrosion testing and likewise requiring welders to make welds having appropriate corrosion resistance. Over thirty years ago, I required both the welding procedure for 2205 duplex stainless steel and the welder to be qualified by corrosion testing in addition to the mechanical property/weld soundness tests.

RE: Essential variable . PQR

In general, AWS places additional prohibitions on WPS/PQR qualifications which may otherwise be interpreted by Section IX users as "nonessentials", or performance qualification characteristics.

This was driven largely by the fact that AWS Codes such as D1.1 do not stipulate mandatory NDE like the various ASME construction codes, and consequently, the committee members imposed additional conservatism. This is a topic that frequently comes up during the AWS committee meetings, and may change someday, but would represent a significant departure from the trend of AWS Codes.

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