Post weld baking / heating of P No.1 material considered PWHT as per ASME Sec IX.

[Ishack]

Hi All,

Client specification calls for post weld baking/heating (not stated as PWHT) of a P No.1 material after welding for a specific reason. Does it consider a PWHT condition as per ASME Sec IX QW-407.1(a) Point#2, i.e PWHT below lower transformation temperature?

If it is considered as PWHT as per the clause above, then would a PQR with 200 Deg C PWHT qualifies to perform PWHT on the weld at 600 Deg C which is below the lower transformation temperature of P No.1 keeping all other essential variables same.

Note: Though there is an interpretation available (IX-04-03), it doesn't state the answer instead it refers to QW-407.1 (throwing the ball wisely).

 

[DekDee]

QW 406.11 dealt with a postweld bakeout (it was not even listed in the variables) and it was deleted from the 2017 edition.
My opinion only is it would not be classed as PWHT.
Regards,
Shane

 

[DVWE]

Does it consider a PWHT condition as per ASME Sec IX QW-407.1(a) Point#2, i.e PWHT below lower transformation temperature?

No. PWHT temperatures must meet minimum requirements of other codes. ASME B31.3, B31.1, Section VIII, Div 1, PWHT minimum for P-No. 1 is 595C (1100F). 595C minimum must be achieved before it is considered PWHT.

If it is considered as PWHT as per the clause above, then would a PQR with 200 Deg C PWHT qualifies to perform PWHT on the weld at 600 Deg C which is below the lower transformation temperature of P No.1 keeping all other essential variables same.

No. Same as above.

The devil is in the details; she also wears prada.

 

[weldstan]

In the 45 years past that I have been involved with dehydrogenation heat treatments, ASME IX has never considered this treatment as a post weld heat treatment.

 

[CWEng]

Have you seen interpretation IX-83-29?

Question(s) and Reply(ies):

Question: For procedure qualification under QW-407.1 and QW-407.2, is "post heating" at 572° ± 18°F for 7 hr for the purpose of hydrogen removal immediately following welding considered to be a "postweld heat treatment" below the lower transformation temperature per QW-407.1(a)(2)? Both "post heating" and "postweld heat treatment" are independently defined in QW-492.

Reply: No.