PWHT and Welding Procedures
PWHT and Welding Procedures
(OP)
According to B31.1 (para. 132) you do not have to PWHT P5A (2.25 Chrome) material if it is 4" in diameter or less, 1/2" thick or less and has .15% carbon or less.
We are having a debate as to whether this exemption allows you to weld the material with a procedure that has been qualified with PWHT, or do you have to have a procedure qualified without PWHT.
I believe that since PWHT is an essential variable you will have to have a procedure that has been qualified without PWHT.
I would appreciate knowing how everyone here interprets this section of the code.
Thank you,
Lalaith
We are having a debate as to whether this exemption allows you to weld the material with a procedure that has been qualified with PWHT, or do you have to have a procedure qualified without PWHT.
I believe that since PWHT is an essential variable you will have to have a procedure that has been qualified without PWHT.
I would appreciate knowing how everyone here interprets this section of the code.
Thank you,
Lalaith





RE: PWHT and Welding Procedures
QW 407.1
A separate procedure qualification is required for each of the following conditions.
(a) For P-No. 1, P-No. 3, P-No. 4, P-No. 5, P-No. 6, P-No. 9, P-No. 10, and P-No. 11 materials, the following postweld heat treatment conditions apply:
(1) No PWHT;
(2) PWHT below the lower transformation temperature;
(3) PWHT above the upper transformation temperature (e.g., normalizing);
(4) PWHT above the upper transformation temperature followed by heat treatment below the lower transformation temperature (e.g., normalizing or quenching followed by tempering);
(5) PWHT between the upper and lower transformation temperatures.
(b) For all other materials, the following postweld heat treatment conditions apply:
(1) No PWHT;
(2) PWHT within a specified temperature range.[A99]
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RE: PWHT and Welding Procedures