thePetroStreet

saadsh,
P22 is highly hardenable steel and even controlling prehating temperature, the best hardness reading comes to be around 290 HB. There are certain ways you can control the hardness of P22 steel during welding like using high preheat temperature 250 deg C, use of temper bead technique, post heating to 300-350 deg C and then to cool under insulation. And if all these conditions are met, even then you are not sure about the reading of hardness whether it will come in acceptable limit or not. And in case, if rain water has been splashed over the weld how hardness would be in acceptable range; as per my knowledge, it would never be.

@all
ALL OF you are talking about the hardness acceptable limit of P22 material
is there any document or para that refer the acceptable limit for hardness of different materials
i have seen ASME SECTION II part A but i got nothing about Hardness limit
will you quote any code with reference clause for acceptable limits of hardness of different materials?

We are talking about the hardness limit of P-22 piping weld after PWHT and the hardness acceptable values have been given in ASME B31.3 for all piping materials in heat treatment table 331.1.1and for P-22 (P.No. 5), the max. acceptable value is 241 HB.

oka thanks for this info

is there any such reference of Hardness after PWHT of pressure vessel's weldment fabricated as per ASME VIII?

ASME BPVC Sec. VIII does not require hardness after PWHT operation.

then how u ensure that PWHT of vessel fabricated as per ASME BPV SEc VIII is conducted properly?

I suggest that if you want to discuss further, initiate a new thread with a defined subject.
Hope you understand.