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[MW:2396] QW-407 Postweld Heat Treatment

By Materials & Welding
QW-407 Postweld Heat Treatment
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
QW-407.4 For ferrous base metals other than P-No. 7,
P-No. 8, and P-No. 45, when a procedure qualification test
coupon receives a postweld heat treatment exceeding the
upper transformation temperature, the maximum qualified
base metal thickness, T, shall not exceed 1.1 times the
thickness of the test coupon.
Dear Members,
Above mentioned subject and clauses are referred..I have a few question to ask..
1.  What "PWHT below the lower transformation temperature" means and from where we can get the value of temperature?
2.  What "PWHT above the upper transformation temperature" means and from where we can get the value of temperature?
3.  What "PWHT within a specified temperature range" means and it is from code and standard such as B31.3, ASMEVIII or etc?
I really need your expertise opinion. Thank in advance
Regards
Tong


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