Re: [MW:11012] Stress Relieving

Hi,

Just to add over wondrful response given by Mr. Goswami:-

Materials subject to Intermediate stress relief and PWHT shall be subject to verify that their mechnaical properties have been retained after heat treatment cycles, Tests shall include two aditional PWHT cycles to account for Future repairs or alteration

Speak to the manufacturer to add Simulated PWHT for each heat subject to PWHT, some may guarantee 3 PWHT cycles max.

Assuming qualification in accordance with ASME Sec ix,  QW-407.2- total aggregrate PWHT time including any repairs can not exceed PQR time/0.8.


Regards
Manpreet Singh



On Mon, 09 May 2011 22:32:14 +0530 "pgoswami" <pgoswami@quickclic.net> wrote
>

Abhishek,

You 're certainly familiar, that any PWHT operation consists of heating cycle, soaking/holding cycle and cooling cycle. Holding cycle, i.e temperature and timeare most important. Any prolonged exposure at this temperature range may harm materials properties(especially hardness and notch toughness).If the power is back within a short while, while the material is in the soaking/holdingrange, thenit's not a major issue.

If the PWHT had to be called offor abandoned before the soaking cycle (i.e interruption happened during heating) it may not havemajor adverse effect on materials. However calling off PWHT within the soak cycle or in the cooling cycle (past soaking) andwith multiple repeat should be carefully assessed.

For a dissimilar material combination (P1=P4, P1= P5), depending on the designcode the recommended PWHT temperature would exceed the leaner one (P1).Hence multiple soaking at the PWHT temperature range could cause appreciable drop of mechanical properties of P1 material (especially toughness and hardness).

If there're any data available on simulated PWHT on these materials this would help.

If you look in AWS D-10.10-1999, clause 12.6 addresses this issue, but the answer is subjective.

B-31.3, calls for thermocouples to be attached during PWHT:

Clause 331.1.6: Temperature Verification. Heat treatment temperature shall be checked by thermocouple pyrometers or other suitable methods to ensure that the WPS requirements are met. See para. 330.1.3(b) for attachment of thermocouples by the capacitor discharge method of welding

Hope this would clarify your query.

Thanks.

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

>

---

From: ABHISHEK GHOSH [mailto:ghoshabhishekmech@gmail.com]
>Sent: Friday, May 06, 2011 4:40 PM
>To: materials-welding@googlegroups.com
>Cc: pgoswami@sympatico.ca; pgoswami@quickclic.net
>Subject: Stress Relieving
>
>

Dear All,

During PWHT ( SR ) at site , any time SRcan beinterrupted due to power failure, may be sometimes for rain, SR is stopped ..How many times we can make Re SR for A 106 Gr B?what to do with Sa 335 P5, P9 , P11 pipes???

In B 31.3 where no of thermocouples to be used is mentioned ??

Regards.

>--
>

ABHISHEK GHOSH
>FAHAHEEL, KUWAIT
>MOB: (00)965-60303798
>

>

--
>To post to this group, send email to materials-welding@googlegroups.com
>To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
>For more options, visit this group's bolg at http://materials-welding.blogspot.com/
>The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
>

Treat yourself at a restaurant, spa, resort and much more with Rediff Deal ho jaye!

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.