thickness for PWHT (after forming or before forming)

[arash2000]

Dear All

As per PD5500 for M1 material group PWHT is required for plates over 35 mm.

I want to know if this thickness refers to thickness "before forming" or it refers to thickness "after forming"? (not considering elongation or sour service)
I am dealig with a pressure vessel that the thickness of head is 34 mm after forming while original plate thickness was 42 mm before forming!!!!!!!!!!!!

Please advise me in this regard!

thanks

 

[metengr]

arash2000;
For most Codes and Standards the thickness for PWHT requirments is the final thickness after all forming is completed. Thermal treatment for post forming operation is a separate issue and you must review the particular Code or Standard for guidance.

 

[DVWE]

Does the vessel otherwise require PWHT?

 

[doct9960]

arash2000,

What is the thickness of the shell where the head is connected?

For butt welded joints, Section 4.4.3.3(a) of PD 5500 defines nominal thickness to be used in applying the requirements for PWHT as the thinner of the two parts butt welded together.

The thickness of the straight flange of the head will still be 42 mm. If the nominal thickness of the shell is greater than 35 mm, PWHT is required.

 

[vesselfab]

For Heads we use the nominal thickness for PWHT cycles.

If the head has an opening in it, we Ultrasonic the area around it to get an actual thickness being welded there so see if it is in the PWHT range. over 1.5" here for ASME for p1 materials