PWHT on ASME sec VIII div. 2

[sadminto6]

Dear Guys,
I am building a new spherical thank Material is SA537-Class1, wall thickness= 31 mmm.
According to ASME sec VIII div 2. PWHT not mandatory , but user want to perform PWHT.
Fabricator of plate said :
ASME-SA-537 ( 65mm and under),Code Requirements: Tensile Strength :485 – 620 MPA
Expected Value after PWHT : 400 – 530 MPA.
So, after PWHT the Tensile strenght can be under the Code requirement ( 400 < 485)
Is this permitted by code (ASME sec VIII div.2) ?
Thanks in advance !

 

[metengr]

For purchasing of pressure vessel plate, the requirements of SA 20 must be met. For your case, if the concern regarding PWHT will reduce the strength properties, I would suggest you specify Supplement S.3. This Supplement is a "Simulated Post-Weld Heat Treatment of Mechanical Test Coupons" to determine if the strength properties degrade as the vendor suggests. If the properties degrade, you can use the results from this Supplement to discuss with the client.

Typically, for the normalized Class of material the strength properties will degrade slightly but not below the minimum. Typically, the actual strength properties come in well above the minimum values per the material specification.