Multi-process PWPS

Date 06-14-2021 22:52 Edited 06-18-2021 21:33

Hello everybody, first post on here after stalking this forum for years. Glad to be here, I have gotten so much good information just observing from the outside I am looking forward to both asking my own questions and contributing to the discussion as well. Now down to business.

I am being asked about performing a CJP between some 3/4" thick stainless plates that will be put together to make, essentially a tube shape, onto a 2" thick stainless base plate with a backer and then UT'd after. Our shop foreman wants to use GTAW to weld the root pass and then GMAW or FCAW for the fill passes. When asking about just using GMAW or FCAW for the entire thing the shop foreman mentioned weird reflectors during the UT process, so he wants to do GTAW to keep the root pass clean to avoid this and I can't argue against that since I have seen it too.

Looking in D1.6 I see that GTAW, GMAW & FCAW, all have prequalified groove weld joint details. TC-L4a for GTAW and TC-U4a-GF for GMAW and FCAW.

So now down to the actual question, can I make a multi-process PWPS or would I need to perform a PQR and then make a WPS based on that since I am mixing processes?

Any guidance will be greatly appreciated guys, thanks.

LD

By SWN1158 (***)

Date 06-15-2021 13:02

David, Clause 6, particularly 6.1.4.2 may be helpful...

6.4 Essential Variables

6.4.1 Welding Procedure Essential Variables.

The Welding Procedure Specification (WPS) shall document all essential variables and supplementary essential variables, when required, as summarized in Tables 6.1 and 6.2. When a welding procedure includes multiple processes, the WPS shall include essential variables applicable to each process.

When multiple processes are used for qualification of a single welding procedure, they may be used individually, but only within the qualification and thickness limits of Tables 6.1, 6.2 (when applicable), and 6.3 for that process.

6.4.1.1 Changes to Essential Variables. Any change to an essential variable beyond the limits set forth in Table 6.1, Table 6.2, or Table 6.3, as applicable, shall require qualification of a new or revised welding procedure.

6.4.1.2 Welding Procedures with Multiple Processes. When a welding procedure has been qualified using multiple processes to produce a single test weld, separate WPSs for each process may be created for each process. Essential variable limits of Tables 6.1 and 6.2, as applicable, and thickness limits of Table 6.3, shall apply for each process individually.

(1) When qualifying a WPS involving multiple welding processes to be deposited in a single joint, the approximate thickness of the deposited weld metal from each process and for each set of essential variables, and supplemental essential variables when applicable, shall be recorded on the supporting PQR.

(2) The tension, bend, notch toughness, and any other mechanical test specimens shall include weld metal from each welding process and combination of essential variables, and supplemental essential variables when applicable.

By twistedmetal208 (*)

Date 06-18-2021 21:32

Excellent that is what I was looking for... to be honest I am kind of embarrassed I did not find it right away, it is very obvious in D1.6.

I also had in mind the same question regarding D1.1-2020 and I do not see anything specific on it other than 5.5.5 which refers to a GMAW root pass with SAW on top of it. Specifically I would be interested in a GMAW root pass with FCAW cap (first with backer and one without backer and backgouged and finished with FCAW). The statement in 5.2.2 "Combination of WPSs. A combination of qualified and prequalified WPSs may be used without qualification of the combination, provided the limitation of essential variables applicable to each process is observed." This sounds like it is intended to mean PWPS-WPS is indicated unless it is read as a combination of any combination of those, such as a WPS-WPS, a PWPS-WPS, or a PWPS-PWPS. The 5.5.5 clause that has the specific combination of GMAW-SAW makes me think it is intended as the former and not the latter.

Let me know what you think.

LD

By SWN1158 (***)

Date 06-21-2021 17:21

If you’re using two prequalified D1.1 processes, and you don’t exceed the essential variables limitations for each process, you should be good to go.