Qualifying a WPS from multiple PQR's 1

[deco0404]

Hi guys,

hope someone can offer some advice here. What I would like to know is if there is a limit to the amount of PQR's which can be used for a single WPS? We are doing a project for the offshore sector, and have recently had a contractor who had quite a complex weld to do. In their WPS they listed 10 different PQR's as qualifying this document. I was amazed that they would do this, but I could find nothing to argue against it. They maintain this practice is ok.....

Any opinions or advice....

We mostly work to DNV/GL rules, but would take guidance relating to any spec..

regards

Declan

 

[Don56]

You may create a WPS backed up by multiple PQR's. There is no limit to the number of PQR's per WPS. See ASME Section IX QW-200.

(f) Multiple WPSs With One PQR/Multiple PQRs With
One WPS. Several WPSs may be prepared from the data
on a single PQR (e.g., a 1G plate PQR may support WPSs
for the F, V, H, and O positions on plate or pipe within
all other essential variables). A single WPS may cover several
sets of essential variable ranges as long as a supporting
PQR exists for each essential and, when required,
supplementary essential variable [e.g., a single WPS may
cover a thickness range from 1/16 in. (1.5 mm) through
11/4 in. (32 mm) if PQRs exist for both the 1/16 in.
(1.5 mm) through 3/16 in. (5 mm) and 3/16 in. (5 mm)
through 11/4 in. (32 mm) thickness ranges].

 

[deco0404]

Thanks for the post Don, very helpful.

This probably should be part of another thread, but how can this be controlled. What I mean by this is that differently qualified procedures will use different weld settings, and most importantly different heat inputs...Is there any way to tell whether by using all these PQR's (each of which has successfully been qualified), that the interaction of them all together will give the required strength and impact properties required....

Declan

 

[Don56]

That is where it gets complicated. All the PQR's may not even be necessary for the weld you need to perform, however someone combined all of them to create a God's gift to welders WPS that covers everything he could think of. You will have to dissect them. I'd start by defining the essential variables of the weld to be performed. Then start analyzing the PQR's for these requirements. You may get lucky and not have to go through all of them to satisfy your needs. That rarely happens, but you can hope. Good luck. Sounds like the welding has been performed, so even if you find what you need for your weld in less than 10 PQR's,the WPS still has to be justified. Any essential variable in it has to be supported by a PQR.

 

[SectionIX]

Don,

Agreed with your comments.

One vendor of mine throws in PQR's that are not relevant, e.g. wrong process, heat treatment, materials, etc. that don't in any way, in whole or part, support the WPS. His reward is the WPS gets summarily rejected. Supplementary and Supplementary Essential variables for all PQR's must support the WPS. If not, the WPS is not valid.