PWHT Holding Time

The PWHT is recommended for relieving stresses developed during welding and is meant for medium CS beyond 20 mm thick. or for materials with higher carbon content or for alloy steels where Cr, Mo ( stress risers) and other alloys induce more stresses during welding.

The temp. selection depends upon the carbon percentage. It could be 600 ± 20 ⁰ C for CS with C % up to 0.20 and thick. On higer side or 620 ± 20 ⁰ for Carbon beyond 0.25 %

For soaking time general thumb rule is 1 hour soaking time per ( 1 inch thick.) 25 mm thickness. Hence for 38 mm it should be 90 minutes. For 43 mm thick, it could be 2 hrs. or nearest.

For Alloy steels the soaking temp. may vary depending upon alloy content, but soaking time pattern is same like for CS.

Sridhar.

Dear Abdel Sir,

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with best wishes for you and for the forum

p k mohapatra

Dear Abdel:

Your answers are always great. But I can not go the links you provided. I don't know why and would you help me?

Hi Dragon1,

if u want that pdf file,pls give your mail id, i will send it to u...

no problem.....k

bye

Rajasekar

My e-mail is Feng.Lu2@nov.com

Thank you very much!

Dear Abdel Sir,

Your really great,

Thank You very much sir.

Regards

Rajasekar

May I know what the purpose of this soaking time is? If rationale behind this is to dissipate the heat to all areas of the component and to allow the carbides for SCC prevention, then post construction repairs could easily jeopardize the production quality fabrication. If this time is determined based on empirical results of tempering time (Hollomon Jaffe parameter), then does the configuration (shape) affect this time? When the range of soaking time is used to qualify a weld (Section IX QW403), we do see the loss of ferrite, impact toughness - in essence there is a change in properties. To me, just thickness, composition or just 80 or 120% aggregate time alone cannot guarantee the joint integrity of PWHT during the life cycle. In short, my question: what is the best soaking time (cumulative simulated hours) we need to arrive at during PQR for such PWHT welds?