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Up Topic Welding Industry / Inspection & Qualification / Prequalified WPS
- - By tsmart Date 09-16-2015 02:14
I am having a discussion with another CWI at work about keeping prequalified WPS's on hand and in written form for welder on the floor, or if need be, when being audited. Anyway, he says that B-U4a-GF p98 D1.1 also qualifies TC-U4aGF p99 D1.1.  He argues the joint detail does not change, being a single bevel groove, regardless of it being a Butt, Corner, or T joint. I disagree, I think two separate WPS's need to be on the shop floor for these to joints. Table 3.8 D1.1 under weld details 24) A change in groove weld details as shown in 3.3 or 3.4. I understand they are both single bevel groove welds, but why would there be two separate weld details separating a Butt joint from a Corner or T joint if two separate WPS's were not needed. Thanks
Parent - By dick (**) Date 09-16-2015 08:07
If I remember correctly might be confusing pjp vs cjp, not sure, but think I seen this b-4.
Can't say for sure right now, no book, hopefully we will gets some help.
- By In Tension (**) Date 09-16-2015 17:08
I know you're more looking for a semantic code answer to settle the score between you and the other CWI so here's the short answer:  You're correct.  One isn't a substitute for the other.
Here's the longer answer:
The question is based on the false premise that you would have two separate WPS's in the first place if both joint types take place in your shop.  The premise is moot because it's permissible to combine both B-U4a-GF and TC-U4-GF into one WPS (have a look at 3.6.1).  You now have a single prequalified WPS that covers both joint types for single bevel grooves.  It has to anyway be in written form so you might as well have it cover what it can, within reason.
Here's another (slightly off-topic) thing to consider when trying to square away for an audit... your 3rd party may not be a welding-savvy CWI.  So, if two CWI's can't agree on an issue imagine the perspective some anal QA-type auditor might take.  If you don't combine your WPS's into one comprehensive WPS then it's better to have them both on the floor and available to the welders than to argue that one covers both because joint type isn't an essential variable.  Which brings me back to it being a moot point.
Take care!
- - By 803056 (*****) Date 09-16-2015 22:01
The joint detail clearly changes when comparing the B-U4a-GF to the TC-U4a-GF. The B-U4a-GF is a butt joint made with backing. The other is either a corner or T-joint utilizing backing. Both have different restrictions with regards to what positions can be welded. Example; B-U4a-GF is restricted to both flat and horizontal positions when the root opening is a nominal 3/8 inch and the groove angle is 30 degrees. The TC-U4a-GF is limited to the flat position when the root opening is 3/8 inch and the groove angle is 30 degrees.

If the contractor uses either joint detail (3/8 root opening with 30 degree groove angle) in a position other than what is listed, it no longer meets the requirements of prequalification. Therefore, the contractor is required to qualify the WPS for a position that is not prequalified. Also, check the other footnotes listed for each of the groove details, they are not the same.

Things get a little sticky when one considers the "as fit-up" tolerances. There appears to be a little overlap. I'm not saying this wouldn't provide hours of interesting conversation when tolerances are considered. It isn't a clear cut case, but I understand why the committee decided to use two separate sketches and decided not to call it a B-U4a-GF. 

The WPS should include a reference to the prequalified joint details or sketches of the joint details included by the prequalified WPS. It is the contractor's choice to limit the WPS to one specific prequalified joint detail or to use a general WPS that includes all the prequalified details. It is the contractor's choice to have a separate prequalified WPS for fillet welds and another for groove welds or to use one prequalified WPS for both grooves and fillet welds. However, the prequalified WPS is only prequalified if the joint details comply with the requirements of Figures detailing the prequalified joint details. If the production conditions do not comply with the figures, the WPS is not prequalified.

Best regards - Al
Parent - By tsmart Date 09-16-2015 22:36
Thanks for all the responses. Everything in the WPS would be prequalified, nothing out of the ordinary. Its just two stubborn, proud CWI's not wanting to back down. I just lean towards being on the safe side with as much flexibility as possible, while limiting unneeded, costly, PQR/WPSs. Thanks again.
Up Topic Welding Industry / Inspection & Qualification / Prequalified WPS

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