POST WELD HEAT TREATMENT [STRESS RELIEVING]
POST WELD HEAT TREATMENT [STRESS RELIEVING]
(OP)
Good day!
I have been struggling what temperature to use for our PWHT using stress relieving.
I saw the definition of stress relieving which says that material is to be heat treated below its critical temperature.
In Phase Diagram of Heat Treatment
, critical temperature is 727 degrees celcius.
In ASME SECTION V111
, normal holding temperature for PWHT is 595 degrees celcius which is below 727 degrees celcius.
So meaning, any temperature lower than 727 degrees celcius will do?
Our product is transportable pressure vessel having a thickness of 6mm only and total height of 350mm.
I am planning to use 200 degrees celcius only since the thickness is too thin. Is it possible?
By the way we used low carbon steel material.
Thank you.
I have been struggling what temperature to use for our PWHT using stress relieving.
I saw the definition of stress relieving which says that material is to be heat treated below its critical temperature.
In Phase Diagram of Heat Treatment
, critical temperature is 727 degrees celcius.In ASME SECTION V111
, normal holding temperature for PWHT is 595 degrees celcius which is below 727 degrees celcius.So meaning, any temperature lower than 727 degrees celcius will do?
Our product is transportable pressure vessel having a thickness of 6mm only and total height of 350mm.
I am planning to use 200 degrees celcius only since the thickness is too thin. Is it possible?
By the way we used low carbon steel material.
Thank you.





RE: POST WELD HEAT TREATMENT [STRESS RELIEVING]
If you need to PWHT, follow the requirements in ASME Section VIII, Div 1 Part UCS for carbon and low alloy steels. These are minimum values so you must perform at or above this temperature. Thickness has nothing to do with temperature, it is for holding time at temperature. At 200 deg C this is too low for adequate PWHT, you must be at least 595 deg C or higher but do not exceed the lower critical transformation temperature of 720 deg C.
RE: POST WELD HEAT TREATMENT [STRESS RELIEVING]
RE: POST WELD HEAT TREATMENT [STRESS RELIEVING]
RE: POST WELD HEAT TREATMENT [STRESS RELIEVING]
Now, it is confirmed. The auditor wanted us to do PWHT for all sizes.
RE: POST WELD HEAT TREATMENT [STRESS RELIEVING]