WPS/PQR

By jon20013 (*****)

Date 12-30-2006 02:32

Normal thoughts are a PRELIMINARY WPS is drafted, the values of which are run on test pieces which, upon passing tests becomes the basis for the PQR(s) from which the WPS(s) are developed.

By dbigkahunna (****)

Date 12-31-2006 17:03

It was explained to me many years ago this way. A WPS is a book on baking bread. A PQR is a recipe for baking bread. And a WPQ is to see if the baker knows how to bake bread using the recipe.

By jon20013 (*****)

Date 01-02-2007 18:13

I love that explanation Bigkahunna! Puts things in as simple of perspective as possible!

By HgTX

Date 01-05-2007 21:42

The WPS (welding procedure specification) is the recipe for bread. The PQR (procedure qualification record) is an evaluation of a demonstration loaf. So if anything the PQR might be the book, because you could write a number of WPSs based on that PQR. ("Okay, that tasted pretty good, but I could also write another recipe with a little more salt, within my essential variable restrictions.")

Hg

By CHGuilford (****)

Date 01-02-2007 18:03

I agree that a preliminary WPS comes first. We usually run the welds we want to do on some practice pieces. When everything looks good, we record the parameters on a preliminary WPS. Then a PQR test is run using the preliminary WPS parameters. If the PQR test is successful, the preliminary WPS is now qualified and other WPS's can now be written within the PQR's range of allowable variables -those are considered to be qualified.

It's kind of a which-came-first-the-chicken-or-the-egg scenario (the WPS or the PQR) and I think some folks make a bigger deal of it than it needs to be, but it is a way to show you have control over what you are doing.

To answer your other questions:
Tests needed for the PQR are specified in the applicable welding code. Codes vary a bit so you will need to check it out. D1.1 sec 4.4 is just one example.

You can write a WPS that is qualified by a PQR - remember that you have to remain within the welding codes allowances.

The WPS does not need to be tested, the PQR was the test.

By Golden Arm (*)

Date 01-08-2007 12:23

I was curious, if the WPS comes first how then can AWS have prequalifed procedures? and not have prequalified WPS's as well.

By jon20013 (*****)

Date 01-08-2007 12:48

Golden Arm; AWS permits the use of prequalified procedures (also known as WPSs; Welding Procedure Specifications) based on years and years of committee study of certain factors governing weld joints like base and filler metal combinations, thickness, joint design, preheat, type of loading on the weld joints and a whole host of other things. In "prequalified" applications there is no need for procedure qualification but the user DOES have to write a WPS which follows all of the rules of D1.1. To the best of my knowledge, D1.1 is the only Code in industry that permits the use of prequalified WPS; which must not be confused with SWPS or "Standard Welding Procedure Specifications."

By Lawrence (*****)

Date 01-08-2007 14:16

Jon

FYI:

D1.6 (Structural Welding Code Stainless)
D1.3 (Structural Welding Code Sheet Steel)

Both of these have a Section 3 for Prequalification.

I really wish D1.2 (aluminum had a section 3)

By jon20013 (*****)

Date 01-08-2007 14:29

Thanks Lawrence. It's been way too long since I've worked routinely with either of those standards so I appreciate the correction!

By Golden Arm (*)

Date 01-09-2007 11:45

So you can write a WPS supported by an AWS prequalified WPS with no PQR.

By jwright650 (*****)

Date 01-09-2007 12:13

Yes, but it is not an "AWS prequalified WPS" perse', it is only an AWS prequalified joint configuration in Section 3, Figures 3.3 and Figures 3.4.

Prequalified means you get to waive the testing and write the WPS, but you must meet all of the essential variables to remain prequalified. Lots of terms that can get confusing......

By jon20013 (*****)

Date 01-09-2007 12:37

John, I agree with what your saying, but don't the "suggested" formats for AWS Procedures even show "Pre-qualified" or "Qualified" on the form somewhere?

By jwright650 (*****)

Date 01-09-2007 12:57

Yes, on page 338 of Annex N, the blank sample form has a place at the top to designate whether "prequalified" or "qualified by testing". They have also provided a box to check whether the form is being used for a "WPS" or a "PQR", which may seem confusing at first glance.

On pages 339, 340, and 341 there is the same sample form filled out and showing it being used in different situations.
p339 shows the form being used as a prequalified SAW WPS, p340 shows the form being used as a PQR for FCAW, and p341 shows the form being used as a qualified WPS for FCAW that is being supported by the PQR shown on p340.

By jon20013 (*****)

Date 01-09-2007 13:34

Thanks John! :)