2 1/4 Cr/Mo P22 materials PWHT temp

[deepu78]

P22 Piping materials Tempering process carried out at typically 740degC. Whether PWHT holding temperature for P22 material can be above tempering temperature?

 

[ShabsRBI]

As per ASME Sec IX P22 material falls under P no. 5A and Gr. No. -1.
Looking ASME Sec VIII Div-II Table UCS, Normal holding temperature for PWHT is 675 Deg C with holding time as 1hr/inch with a minimum of 15 minutes.

 

[goutam_freelance]

As per B31.1 table 132.1.1-1, the holding temperature for P No 5A, Group 1 is 675-760 deg.

Again, as per clause 132.2 (a) the upper limit above (760 deg C) may be exceeded but it can not exceed the lower critical temperature, which is 805 deg C for P No 5A (ref 129.3.1-1).