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Up Topic Welding Industry / Inspection & Qualification / WPS AND PQRS
- - By DannyAgudelo (*) Date 04-08-2018 21:58 Edited 04-08-2018 22:21

im trying to understand the correct use of WPS and PQR and have a couple of questions.

1. Can a WPS with a PQR differ from a code or standard. For example AWS D1.1, up to my understanding doesnt approve of the use of e6010 on structural welds. If a WPS were to be written and the PQR used to back it up tested on a specimen that was welded going against the AWS D1.1 and it met the mechanical requirements, could it then be used. Can a WPS backed by a PQR that contradict a code be used? Is it allowed?

2. How is the range of thickness qualified by  PQR obtained. For example if a PQR was made using 3/4 inch plate, how is the range of thickness that will be qualified by this PQR determined?

3. Which parameters should be used to determine a success or fail of a PQR test. For example, testing is done in a plate v groove weld. When the bend test is done, against which parameters is the specimen examined to determined if it was sucessfull or no. EX, if after the bend test there is a crack, against which standards would it be examined to determine the size tolerance of the crack?

Thank you
Parent - - By Steelslinger (**) Date 04-09-2018 11:55
Read Section 4 "Qualification" in AWS D1.1.

All the information you need is there.
Parent - - By DannyAgudelo (*) Date 04-09-2018 17:37
But i was just using d1.1 as a guide. What if its another code, or if its a weld plan thats not on a code or go against a code.
Parent - By Steelslinger (**) Date 04-09-2018 17:42
Each Code will have the information needed to create WPSs to their code. Each one will vary on the means/methods and required info.

If a code is not called out, then you would need the Engineer to state how and what they want to do for qualification of procedures and welders.

Going "against" code is permissible, as long as the Engineer of Record (EOR) signs off on it. The EOR is allowed to deviate from code if they wish, after all, it's their butt on the line. But make sure it is documented to cover your own butt.
Parent - - By Lawrence (*****) Date 04-09-2018 18:46

I think you are going to have to tell us much more about your project....  What you are working with?  What you are trying to accomplish?   Why you might want to do something other than code?

Each code and specification is very different, so you can't really get a general answer to your question that applies across everything.

Tell us the story :)
Parent - - By DannyAgudelo (*) Date 04-10-2018 01:51
I dont really have a project, im just trying to understand correctly how they work. I guess the correct way to put it is if a WPS and its corresponding PQR are always supposed to be backed or related to a specific code and its guidelines, or can they be free standing in the way that the engineer decides how to do it, gets it tested and if it works, it can be done, even if it has no relation to a code, and he even decides the acceptance criteria of the specimen during the pqr testing.
Parent - - By 803056 (*****) Date 04-10-2018 04:54
Each code, while similar in many ways, are different from other codes. The differences may be the width or thickness of the samples subjected to a guided bend test, the dimensions of the reduced section tensile test, or nick break tests are required instead of the guided bend tests. One code may require the welded coupon be X-rayed before the mechanical testing or it may allow UT be used in lieu of RT, or no volumetric testing is needed. So, qualification is usually done to a particular code.

There are some codes that recognize a "mock-up" of the weld used in production. In short, a production piece is subjected to a regiment of tests as described by the applicable code or per the customer's direction. Not all codes recognize this method of qualification.

There are cases where there is no code that applies to the specific application. When that is the case the contractor or customer can decide to adopt a welding standard is "good enough" or they may develop a methodology that provides the data indicating the weld is "good enough" for that application.

Ultimately, it is the Owner that has the responsibility to determine how the welds are going to be qualified, examined, and the acceptance criteria that will be applied. The Owner can either elect to use an industry recognized welding standard or they can develop their own. The exception is when there is a legal requirement that must be satisfied. For instance, for buildings we have the "building code" that is adopted either at the state level or municipal level. That is a legal obligation. The building code will reference the design and fabrication codes that stipulate how the WPS is be qualified.

Some codes recognize prequalified WPSs that are not supported by a PQR. Some codes recognize Standard WPSs that are backed up with PQRs. In some cases the WPS has to be supported by actual testing that demonstrates the welds meet the minimum requirements of the "code."

In short, there is no one answer that is correct in all circumstances.

Parent - By DannyAgudelo (*) Date 04-12-2018 00:46
Thank you very much. Thid answers my question completely.
Up Topic Welding Industry / Inspection & Qualification / WPS AND PQRS

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