PW.39 P15 E Lowered Minimum Temp for PWHT
PW.39 P15 E Lowered Minimum Temp for PWHT
(OP)
I noticed in the 2017 edition the minimum temp for PWHT of P15 E materials has been lowered from 1350 to 1300.
Does this indicate a trend that lowering PWHT temp is desirable for 15E materials? It would seem by doing so it would effect hardness numbers somewhat. Just wondering what was driving this change.
I also see that non mandatory appendix C is now mandatory for P15 E materials if using electrical resistance heating pads. Also wondering what was driving that requirement.
Does this indicate a trend that lowering PWHT temp is desirable for 15E materials? It would seem by doing so it would effect hardness numbers somewhat. Just wondering what was driving this change.
I also see that non mandatory appendix C is now mandatory for P15 E materials if using electrical resistance heating pads. Also wondering what was driving that requirement.





RE: PW.39 P15 E Lowered Minimum Temp for PWHT
RE: PW.39 P15 E Lowered Minimum Temp for PWHT
RE: PW.39 P15 E Lowered Minimum Temp for PWHT
It would also seem a step foward in joining grade 91 to 2.25 cr. by reducing carbon migration when using the lower temp. Or not?
Back in the day the reccomendation for welding grade 91 to itself was to use the higher range 1375/1425 and run it out for a minimum of 2 hrs. I have heard rumors that EPRI has trended away from that but cannot find the actual document to support that hypothosis. Was thinking perhaps the drop in temp to 1300 was related to it.
The latest read I can find free from EPRI is from 2015. In that document they state going down to as low as 1247F ( I realize not acceptable to BPV1)
RE: PW.39 P15 E Lowered Minimum Temp for PWHT
No, the lower PWHT temperature is unrelated to carbon migration. There is a new non mandatory appendix that you will see in the 2019 edition of ASME B&PV Code Section I. It is related to dissimilar metal welding guidance for Grade 91 steel.