In my workplace, we do three kinds of welding qualifications:
- Welding Procedure Qualification.
- Welder Performance Qualification.
- Lot Qualification.
The first two welding qualifications are common to any shop engaged in manufacture of Coded components. The third one, the Lot Qualification, is not a requirement of Section IX. Its’ requirement, instead, comes from the construction code (in the case of my shop, Section III).
Most of the Parts in Section III specify that each lot of consumable to be used shall be subjected to the required tests (lot qualification) specified in NX 2400.
A question that frequently dominates the discourse in my workplace, and forms a subject of debate with the authorized inspector, is inter-dependence of these welding qualifications on one another.
In simple words, for preparing a procedure qualification test coupon – is it required to use a qualified lot of consumable, and a qualified welder?
And, for preparing a welder performance qualification test coupon – is it required to use a qualified lot of consumable, and a qualified WPS?
And, for preparing a lot qualification test coupon – is it required to use a qualified WPS and a qualified welder?
To the best of my knowledge, these questions aren’t addressed in Section III and/or Section IX, except that Section IX in QW 301 specifies that a performance qualification test shall be welded in accordance with a qualified WPS.
The authorized inspector in my work place feels that for each of the welding qualifications, the availability of the other two is imperative, except that more than one type of welding qualifications can be combined in a single test coupon.
This of course meets stiff contestation from my end.
So, in the absence of any relevant stipulation in the Code regarding this matter, what we can do is apply common sense and try to arrive at an optimum understanding.
This article tries to explore the Section IX’s intentions about this matter. For lot qualification, some reference has been drawn from Section III as well, since its’ requirement originates from there. Please note that this discussion has been written ASME BPVC in mind, and might not be contextual for other codes of construction.
First let us see about the performance qualification.
Is A Qualified WPS And Certified Welding Material Necessary For Welder Qualification?
Is a qualified WPS required to prepare the performance qualification coupon? This is an easy one. As per QW 301, performance qualification test shall be welded in accordance with a qualified WPS. There ends the matter.
Is a qualified lot of consumable required to prepare the performance qualification coupon? This hasn’t been addressed in neither Section IX, nor to the best of my knowledge, in any of the construction codes.
A simple understanding says that if a qualified lot is available, great. This helps when and if the performance qualification coupon does not give a desired result, you can rule out the welding material as one of the causes of failure.
If a qualified lot isn’t available, you can still go ahead with the performance qualification as long as the available consumable has been sourced from an approved and reliable supplier.
Edit: Recently I came across an Interpretation that addressed precisely this matter. The Interpretation number is III-1-78-154. Look it up here if you would like. This Interpretation firmly establishes that the welding material used for preparation of performance and procedure qualification test coupons need not be a certified one.
Is A Qualified Welder And Certified Welding Material Necessary For Procedure Qualification?
Now, let us see about the procedure qualification.
A procedure qualification is a bigger deal and carries a greater importance than a, say, performance qualification. Although Code does not stipulate it, it is desirable if a qualified lot and qualified welder are deployed for preparing the procedure qualification test coupon.
The benefit of this is that if one or more tests in the procedure do not meet the acceptance criteria, you have two factors fewer to worry about. If a qualified lot and qualified welder have been deployed, you can rule these two as possible causes of failure.
However, this isn’t always possible. Say, when a shop is being established for the first time, when all welding qualifications are being done for the first time, availability of a qualified lot and qualified welder is not a given.
When such is the situation, it is prudent to look to complete all three – procedure, performance, and lot qualification – combinedly in a single coupon itself. To do this, it must be ensured that all tests required for all three have been covered in the scope of testing.
Edit: This article set out to find out whether Code mandates use of certified welding material and qualified welder for preparing a procedure qualification test coupon.
About the question of qualified welder, we conclude that the Code does not mandate it, although it is desirable to have a qualified welder for welding the PQ test coupon.
ASME Interpretation Settles The Debate
About the question of certified welding material, the Interpretation III-1-78-154 (which is cited a few paragraphs above) finally brings some clarity to the matter. In this Interpretation, the Section III committee firmly communicates that a certified welding material is not necessary to prepare the welding procedure qualification test coupon. This settles the debate.
Although this does bring a question to the fore, as it did in the minds of committee as well (visible through their reply in the interpretation).
The procedure qualification requirements of Section III NB include impact tests from weld metal as well (in addition to requirements of Section IX). If the welding material used isn’t a certified one (or a good one, in plainer terms), how would the PQR pass the impact requirements?
Well, it appears that the Committee concluded that that is a risk that the Certified Holder runs. If the Certificate Holder is wise enough, they would use a certified welding material. It is not mandatory though, as the interpretation establishes firmly.
Next up, let us see about the lot qualification testing for certifying welding material in accordance with Section III.
Is A Qualified Welder And Qualified WPS Necessary For Lot Qualification?
Is a qualified welder needed to weld a lot qualification test coupon? If the lot qualification is being done at the Certificate Holder’s works, availability of welders qualified in accordance with Section IX can be expected. There is no harm in using qualified welders for preparing the lot qualification test coupon, and no controversy need arise.
However, if the lot qualification is being done at the supplier’s works (which is commonly the case), availability of a welder qualified in accordance with Section IX is not a given. So, if an unqualified welder prepares the test coupon for lot qualification, does that make the CMTR issued by the supplier any less valid?
No. In my understanding, a qualified welder is not mandatory for preparing a lot qualification test coupon. The Code does not ask for it. There ends the matter.
Is a qualified WPS needed to prepare the lot qualification test coupon?
Section III does indicate that for consumable to be used in electro slag welding, lot qualification coupon shall be prepared in accordance with a qualified WPS. Also, while preparing a test coupon for checking chemical analysis of a consumable envisaged to be used for a corrosion-resistant cladding overlay, the test coupon shall be prepared in accordance with a qualified WPS only.
But the question still remains wide open for all other kinds of processes, and other kinds of welds other than ESW and overlays.
For all processes other than ESW, and for all consumables required to be used on non-cladding applications, is use of a qualified WPS necessary, for preparation of a lot qualification test coupon?
The answer to this is that no, the Code does not mandate use of one of the qualified WPSs for preparing the lot qualification test coupon. The lot qualification test coupon is generally required (unless mandated differently by contract documents) to be prepared in accordance with the applicable SFA specification.
If a qualified WPS to cater to the test assembly described in applicable SFA specification is not available, that is not a problem. Code does not mandate use of a qualified WPS for preparing the lot qualification test coupon. Only the testing requirements specified in NX 2400 need to be fulfilled.
Although, it is note-worthy that Section III does try to bring in some elements of a qualified WPS (with which the consumable would be used for welding in production joints), by stating the following stipulations, in NX 2430:
- Welding of the test coupon shall be performed within the range of preheat and interpass temperatures that will be used in production welding.
- The test coupon shall remain as welded, or shall be tested in PWHT condition if the production welds are to be post weld heat treated. The PWHT holding time given to the test coupon shall be at least 80% of the maximum time to be applied to the weld metal in production application.
The stipulation in point 2 above is almost the same as QW 407.2, and the one in point 1 corresponds to QW 406.1 and QW 406.3..
So, in essence – it is good if the lot qualification coupon is prepared in accordance with a qualified WPS. But it does not violate Code in any way if it isn’t.
Another noteworthy thing here is that Section III, at NX-2420 – last paragraph, indicates that the testing done under the scope of a procedure qualification will also satisfy the lot testing requirements, provided all tests required by NX-2400 are met.
Not A Open And Shut Case
Keeping the above discussion in context, consider the following situation that occurred in my shop recently:
A lot qualification test coupon was prepared for qualifying a SMAW electrode. The test assembly was prepared in accordance with the relevant SFA specification. The WPS used for making the coupon was not supported by a PQR (since a fitting PQR wasn’t available), nor was the welder that did the welding a qualified welder in accordance with Section IX.
The authorized inspector had no problems with this, after some convincing from my end.
The lot qualification passed all the required tests, including radiographic examination and mechanical testing.
It was proposed that the welder that did the welding be considered qualified too, since the coupon underwent a radiographic examination (and met the criteria of QW 191), thus fulfilling the test requirement of a performance qualification.
The coupon was good enough to meet all requirements of a performance qualification, except one small problem. The WPS used for preparing the lot qualification test coupon wasn’t a qualified one (that is, it was not supported by a PQR).
The authorized inspector averred that a welder qualification needs a qualified WPS, in accordance with QW 301. Hence, the welder cannot be considered qualified. Whether the inspector is right or not, is a matter up for consideration.
Obviously, it is not a open and shut case, and probably requires the Section IX committee’s consideration, and reply in an Interpretation.
So this was about the different welding qualifications in accordance with ASME Section IX, and interdependence of each on the other two. I hope the article brings some clarity on the subject for the reader. Would you like to add something? Please do feel free to share your thoughts in the comments section below.