ASME B31.3 PWHT requirements for P No.5A

[mickdale]

ASME B31.3 requirements for heat treatment nominal wall thickness below 13mm.

preheat minimum 175 degrees C but PWHT is not required

The above requirements are different to those stated in ASME B31.1 which require PWHT 675 - 760 degrees C and ASME VIII which require PWHT 675 degrees C

From the above info i do not have to PWHT to comply with ASME B31.3 - but have i missed something as i would have thought PWHT would be required?

any advice greatly appreciated

 

[XL83NL]

IF B31.3 is your design code, and the code does not spell out PWHT requirement, youre not required to do.
The scope of (and piping applications in) B31.1 and B31.3 are different, hence theyre requirements are different.

Do not forget to check if your contract spells out PWHT requirement,s e.g. by means of client specifications.

 

[metengr]

B31.1 2010 Edition, PWHT requirements for P-5A

PWHT is not mandatory for P-No. 5A material under the following conditions:
(a) welds in pipe or attachment welds to pipe complying with all of the following conditions:
(1) a nominal material thickness of 1⁄2 in. (13.0 mm) or less
(2) a specified carbon content of the material to be welded of 0.15% or less

PWHT temperature range is 700-760 deg C.

For B31.3 P-No 5A material, PWHT temperature is 704-760 deg C for thickness greater than 13mm.


Each ASME B&PV code book committee and ASME Piping Code committee is a standards committee of it's own that can make rules applicable to their standard based on safe experience.

 

[mickdale]

thanks for the help guys