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# PWHT

## PWHT

(OP)
How long should we PWHT to stress relieve a PQR coupon 1" thick that would cover production welding and additional PWHT for any repairs that are needed after the initial PWHT?

Thanks

moe27

### RE: PWHT

Can't tell.

What alloy is on both sides of the "coupon"?
What filler material did you use?
What welding method did you use?
Why do you suspect you will need weld repairs at all?
Why would the weld repairs require any different preheat, interpass temperature maintenance, and PWHT than the original welding?

Also: Your PQR coupon is for qualifying a particular single person do perform a weld under specific conditions specified under the original WPS qualification. So, if you have this kind of question about your PQR coupon testing and PWHT/PH, then you have a bad/invalid/unsafe/no WPS qualification at all.

### RE: PWHT

(OP)
P1 material A516 GR 70 group II and a FCAW process.
The question is should you and can you PWHT a qualification weld coupon for a longer period of time to cover any potential weld repair that may be needed in actual production??
Example; If I have a 1" thick test coupon and we PWHT for 1hr per inch at temperature.
What if we PWHT the test coupon for 2hrs at temperature. This would allow for a 1hr PWHT of a production component and still have 1hr left to cover a 2nd PWHT if needed due to any repairs.

Regards,

### RE: PWHT

No. And NO.

You cannot "double" a PWHT time to "add" enough time to do a weld repair.

1. The COUPON is to verify that the tested welder is doing the specific welding job properly and is using the specified procedure AS WRITTEN and AS TESTED by the original WPS qualification. So, doubling the coupon PWHT doesn't verify anything about whether he can or did weld the coupon properly.

2. If the coupon weld failed, he MUST re-weld a new coupon - you don't get to do a weld repair on a test coupon. The game is not played that way. And, weld coupons are destructively tested (bend test, micrograph of the cut sample, hammer test (if structural plate), etc. If it was an RT test that failed, the coupon still still failed.

Are you sure that your WPS calls for PWHT being required for P1 material only 1 inch thick?

### RE: PWHT

(OP)
Thanks for your response but either I am not explaining myself or you are not understanding, anyhow.... This is not to test the welder and there is no existing WPS. I am qualifying (TESTING) a coupon PQR (procedure qualification record) so I can write a WPS, NDT inspections are done after PWHT so if you discover a defect in actual production and have to repair an area on a PWHT-ed $80,000 weldment are you to just trash it and start over....I think not, so my question is, IS it allowed to qualify test coupon with additional time for a 2nd PWHT after any repairs. OK I have a 1" thck weld coupon PWHT for 1 hr....I write the WPS stating PWHT for 1 HR per inch. I am in production and send the$80,000 weldment for PWHT and it comes back and a crack is discovered via NDT. I don't believe I can send the unit back for a 2nd PWHT after weld repair so what is the solution??

Thanks

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