PWHT times and Normalizing of Pressure Vessel

[cmryu]

Dear guys,

We are in a very difficult situation,

One of the Vessel (ID 3000, Shell Thk 35mm, SA516-70N) was over heated over around 800 Deg. C during PWHT for exceeding PWHT temp (650 Deg. C)

The result of this accident, mechanical proporties of vessel material come out to be reduced by 10% for Tensile stress due to this over heating.

at present, our solution is to take it into PWHT furnace for Normazing around A3 temp ( 910 Deg.C)

Please comment us about our solution whether this way is permissible or how to affect materil properties.

 

[metengr]

cmryu;
Can you provide some additional background information, is this a new vessel during shop fabrication?

 

[JStephen]

This would affect welding qualification as well.

 

[cmryu]

this is new vessel.
and also we did PWHT only one times but it was burned during PWHT exceeding temperature 650 Deg.C

 

[metengr]

cmryu;
Obviously, this is a nonconformance. What I would suggest is to weld a coupon using the same material as was used to fabricate the vessel. Follow the same essential welding variables as during original fabrication except perform a normalizing heat treatment, in lieu of PWHT.

Once you have qualified this second weld procedure with a normalizing heat treatment, I would subject the vessel to a normalization heat treatment. Keep in mind that you will have to build some type of bracing to minimize distortion. Have the AI completely involved in this entire process.