welder qualification for P91 GTAW

By dragon

Date 03-29-2005 05:30

can‘t be deemed to be qualified for P91.

By Bill Mc (**)

Date 03-29-2005 13:31

Whats exactly is a P91 material?

By - Date 03-29-2005 13:50

P91 is a "modified chrome". The "P" designation means pipe, A335-P91. The chemical composition is 9Cr-1Mo and V+Nb+N. This is according to the ASTM Specifications for Chromium-Molybdenum Steel Products Forms.

CM

By Bill Mc (**)

Date 03-29-2005 14:09

So is the "P22 GMAW" that the welder is already qualified refering to Group P-No. 22 ...or a SA-335 P22 material?

I understand the SA335-P91 is a P-5B group 2
And if the P22 refers to SA335-P22 (a p-5A group 1 material)

wouldn't the welder be qualified for both?

By - Date 03-29-2005 14:08

According to Sec. IX, P91 is a P-No. 5B, Group 2. P22 is a P-No. 5A, Group 1. I believe QW-403.13 says "A change from one P-No. 5 to another P-N0. 5 (viz P-No. 5A to P-No. 5B or P-N. 5C or vice versa) It appears that requalification is required.

CM

By Bill Mc (**)

Date 03-29-2005 14:15

But is 403.13 applicable (essential variable) for GTAW performance testing?

By GRoberts (***)

Date 03-29-2005 16:11

No, Per QW-356, paragraph WQ-403.13 does not apply to welder qualification using the GTAW process. QW403.18 applies, which references QW-423 (P1-P11 qualifies P1-P11 (among others)). So as far as base metal differances between P91 & P22, the welder would be qualified, but other factors such as filler metal (are they both F6?), pipe diamter and thickness, backing, etc. need to be considered (See all essential variables listed in QW-356).

By Bill Mc (**)

Date 03-29-2005 18:10

Thats my point...all other essential variables aside, with no other info, I would think that the welder is qualified for both materials.

By - Date 03-29-2005 19:19

Sorry Guys, I was not paying attention. I was thinking of procedure qualifications rather than welder qualifications.

CM