Multiple Process WPS
Multiple Process WPS
(OP)
Does Section IX or D1.1 prevent the combining of multiple PQRs, one with PWHT and another without, from qualifying a WPS. A reference paragraph would be greatly appreciated.
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Multiple Process WPS
RE: Multiple Process WPS
At initial thought, I don't think this would be possible as PWHT is an essential variable.
RE: Multiple Process WPS
This is a very common practice, especially with the larger contractors/companies that have dozens of WPS's.
RE: Multiple Process WPS
Sure. I understand that, but for PWHT? Seems to me something like that would only convolute things rather than make them simpler by combining them....but that's just me.
RE: Multiple Process WPS
Our company policy is much more specific so as not to confuse those responsible for PWHT and assuring appropriate preheat and interpass temp. control.
RE: Multiple Process WPS
not dozens, but hundreds of weld procedures.
RE: Multiple Process WPS
RE: Multiple Process WPS
combining wps s is fine as long as PWHT with PWHT
Non PWHT with Non PWHT
you can not mix essential variables like PWHT
RE: Multiple Process WPS
you are probably confusing it with PQR's which you have to have one for every process.
i know shops who do PQR's combinations as well but it is a more complicated matter,
I think the ASME does not like the practice so during audits, i stay away from the practice.
genblr
RE: Multiple Process WPS
Actually, I'm not, but thanks for caring
RE: Multiple Process WPS
It may not be the most simplistic or straight forward means of conveying PWHT (or other) requirements, but it is not prohibited.
RE: Multiple Process WPS
I always thought that the tensile test and bends had to be in the final heat treated condition.
RE: Multiple Process WPS
Can someone please give me a good example of why you would want to do this? For example, maybe a vessel in which some sections require it and some don't?
Everyone keeps saying how common it is, but to me, a better use of combining multiple PQRs into a single WPS would be a qualified range of thicknesses, or similar F-Nos. PWHT? Sure, you can but why?
RE: Multiple Process WPS
Vesselfab- the tensile tests and bend test do have to be in the final heat treated condition. So if you have one PQR with tensile tests and bend tests in the PWHT condition, and one PQR with tensile tests and bend tests in the as-welded condition, there is no reason they cannot support the same WPS.
RE: Multiple Process WPS
I don't mean to play devil's advocate too heavily, but the "what if" scenarios could be played all day. I would like to know of some real life examples from someone who actually does this, why, and how it simplifies things. If it's such commonplace, that shouldn't be asking for too much, should it. Has anyone in this post personally done it?
My shop represents "most fabricators" and of the 100+ WPSs which I am responsible for, I can't think of any off the top of my head which we have done this. A reputable pressure vessel shop should have a weld plan or weld map in place detailing which WPSs and respective NDE apply to the applicable joints on any particular vessel. If a mistake is made, or a change is made, it is easier to revise the document with the appropriate WPS and subsequent NCR if required.
RE: Multiple Process WPS
I have had quite a bit of pushback on this.
RE: Multiple Process WPS
BUT, I think the original poster was talking using two different pqr one in as welded and one in pwht condition to make one weld.
to me this is just wrong. essential variables are essential
RE: Multiple Process WPS
Vesselfab, I don't think that's what he was asking.
RE: Multiple Process WPS
rneill,
What about two PQRs, one with PWHT, and one without, into a single WPS?
Correct me if I'm wrong, but I believe you are talking about something like using GTAW, SMAW, and SAW all in the same weld joint.
RE: Multiple Process WPS
THAT'S WHAT HE ASKED....I THINK
RE: Multiple Process WPS
RE: Multiple Process WPS
Reply; For Section IX application, No.
Rationale; Refer to Section IX, QW-200.2 (f). Multiple PQR's
with one WPS...
RE: Multiple Process WPS
But will continue to not use mixed essential variable pqrs
to qualify a procedure.
I just can not see it as advantageous to do so.
RE: Multiple Process WPS
Yes, I have personally done this and seen it done by others. The main situation I have found it advantageous for is repair projects. If you are doing a bunch of repairs that do not require PWHT, but then later, a find one that requires PWHT, you don't have to go back and question all the previous repairs when you PWHT the entire part. Another situation where it make life simpler, is pipe welding. If you are welding pipes of several diameters, some which require PWHT and some that don't you don't have to keep switching welding procedures back and forth. It is mistake-proofing which WPS to use.
RE: Multiple Process WPS
I appreciate your feedback. Again I say, whatever works best for the shop.
RE: Multiple Process WPS
We roll them into single WPS's for all of our field fabricated pipe. The fewer WPS's you let out into the field, the less confusion among foremen, welders, QC and rod room attendants.
We frequently take advantage of the exemptions in B31.1. Take carbon steel for example. We have a procedure qualified up to 8 inches, we use the same WPS for all of our P1 materials, but we have the option of eliminating PWHT (typically) for welds under 3/4" thickness. The welders themselves do not initiate PWHT, so there is no real confusion. In the field, separating them would serve no meaningful purpose.