PWHT 1

[newbeehere]

Good day to all!
We all know that the purpose of PWHT is to remove the residual stress caused by welding and also removal of hydrogen which may induced during welding.
Can somebody explain to me these things:
1. What happen to metal structure when the temperature reaches to 750 degrees Celsius (example temperature), during holding time of 1 hr and 30 mins, and eventually cooling?
2. Why it is called "SOAKING"?

Please share more basic information regarding PWHT.
Thank you so much.

Sincerely

John
(NEWBEEHERE)

 

[pennpiper]

You could do some research here:

http://www.twi-global.com/technical...-heat-treatment-stress-relief-heat-treatment/

or here:

http://www.nationalboard.org/index.aspx?pageID=164&ID=177

etc:

http://www.esabna.com/us/en/education/blog/what-the-welding-inspector-should-know.cfm

Sometimes its possible to do all the right things and still get bad results

 

[quatle]

one more question.

our Client Piping fabrication specification required for PWHT is 19mm and above, I think this specification don't update by latest Code ASME B31.3. the Code 2014 required more than 25mm for PWHT, so what we should follow code or Client Spec.

thanks

 

[BigInch]

Any owner can make their specifications more demanding than any code and they routinely do so. Follow the client specifications, unless you are first able to obtain their agreement to do otherwise in writing.