Sec IX: Single Process WPS qual'd by Combo PQR 1

[StevenHPerry]

Originally posted, mistakenly, in the metallurgy forum. I am not trying to double post. This belongs here in welding. -SP
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Can someone double check my interpretation of Section IX QW-200.2.(f) and QW-200.4?

Proposed WPS:
GTAW 1/4" <= t <= 1/2"

Supporting PQR:
Coupon t = 1"
Root to 0.5" welded by GTAW conforming to the proposed WPS
0.5" to 1" welded by SMAW

The contractor contends that, per QW-200.4, and QW-200.2.(f), the PQR supports the WPS because it is a subset of the coupon tested.

I take it a different way.

QW-200.2.(f) requires the essential variables to be the same. The examples given are essentially subsets of what would otherwise be a more inclusive WPS (i.e. only using a portion of the thickness permitted by PQR) or PQR (i.e. splitting a PQR into two coupons and certifying them separately). Changing the welding process has got to count as more than an essential variable but I do not know what else to call it.

QW-200.4 covers WPSs of multiple processes (para (a)) which may be qualified as separate PQRs (para (b)), but does not seem to cover single processes qualified by PQRs using a combination of the allowed processes. E.g. qualify SMAW and qualify GTAW within the bounds of this section, and you could merge them into a single WPS that combines GTAW and SMAW.

In my view, neither of these sections support using a GTAW/SMAW combo PQR coupon to qualify a GTAW only WPS.

Who is closer to the truth?

- Steve Perry

http://www.linkedin.com/in/stevenhperry

This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.

 

[metengr]

Your contractor is correct. Look at QW-200.4 (a)

 

[Kiwi2671]

Steve,
Metengr and your contractor are correct.
See interpretation below

Interpretation: IX-95-10
Subject: Section IX, QW-200.4, Combination of Welding Procedures
Date Issued: March 17, 1995
File: Question: May a single process WPS be qualified by a combination process PQR where no
essential variables for the process are changed?
Reply: Yes.

This link below gives a pretty good explanation but also raises the question as to why it is allowed by ASME but not by AWS.

http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=143372;hl=combination of processes

Regards,
Kiwi

 

[StevenHPerry]

Thank you, both.

metengr, The third paragraph of QW-200.4(a) doesn't seem to directly answer the question, though it answers the real question and then just makes it a paperwork issue. It states that a WPS may be dissected and used separately. It doesn't state, like the interpretation kiwi posted, that a PQR can be severed and used independently.

Semantics, I guess.

-SP

 

[metengr]

StevenHPerry;
It does, but this is why the code committee issues interpretations. I see your point, sometimes I am too close to this stuff.