The welder has to follow a welding procedure specification that was/is qualified by testing or purchased from AWS as a Standard WPS. The WPS is no more than written work instructions for the welder providing information regarding what base metals can be welded, what welding process(es) is to be used, what filler metal and shielding gas (if required) is to be used, and so on.

If the WPS is qualified by testing, i.e., if there is a supporting PQR, that is fine. The PQR is simply as record of how the WPS was qualified. The PQR has little to do with the actual performance test. The base metal may be different, the thickness may be different, filler metal classification may be different, and the joint detail may be different from what the welder uses for the performance test.

As an example, if the PQR utilized a 1 1/2 inch thick plate, the WPS is qualified up through 8 inches maximum. The weld on the other hand may only use a 1/2 inch plate with three layers and be qualified for unlimited thickness. The PQR may be qualified using GMAW spray mode with ER70S-2 where as the welder may use ER70S-6.

I usually write a WPS specific to the performance test being given. A production WPS may be qualified for positions, for square grooves, V-grooves, bevel grooves, welded from one side or both sides. The same WPS can be used for fillet welds. However, the welder performance test is going to specify a V- groove without backing, a 75 degree groove angle with a root opening of 1/16 inch must be used. The WPS is going to direct the welder to use E7018 for the entire weld made in the 6G position. The WPS for performance qualification is going to be very specific and it isn't going to allow the welder much latitude. After all, the welder is taking my performance test. When he owns the company then he can dictate what test parameters he wants to use assuming he qualified the WPS (it has a supporting PQR) or if he purchased a SWPS from AWS (It isn't my concern if he wants to throw him money down the potty hole).

Best regards - Al