Heat Treatment A335 P91 Assistance
Heat Treatment A335 P91 Assistance
(OP)
I have some in service steam piping, 9Cr 1Mo V Grade P91 with soft spots. Hardness values ~160 BHN. I am wondering if re Normalizing and Tempering will restore the strength of this material with any success. (Awaiting field insitu replicas as well).
If this is an option, does anyone have ideas on a practical normilizing temperature? In mid shutdown right now with lot's on the go.
Any thoughts / experience would be much appreciated.
If this is an option, does anyone have ideas on a practical normilizing temperature? In mid shutdown right now with lot's on the go.
Any thoughts / experience would be much appreciated.





RE: Heat Treatment A335 P91 Assistance
Reply: Yes. The current pipe material hardness is too low. You did not mention how the hardness data was obtained. Field hardness testing must be done using a qualified procedure because surface preparation is vital to assuring accurate hardness data. I have seen so-called soft spots due to inadequate surface preparation (decarburization).
Follow the N&T heat treatment requirements in accordance with the material specification ASME SA 335 Grade 91.
RE: Heat Treatment A335 P91 Assistance
RE: Heat Treatment A335 P91 Assistance
RE: Heat Treatment A335 P91 Assistance
You have confirmed my assumptions and I will procede with recommendations with greater confidence. I will also let you know how we make out.
Again this site has proven to be a priceless resource.
RE: Heat Treatment A335 P91 Assistance
Have you got a contact or website I could pursue wrt heat treating?
RE: Heat Treatment A335 P91 Assistance
Mike Johnson
724-982-0660
mfj@solaratm.com
RE: Heat Treatment A335 P91 Assistance
If you can, use one of the reputable pipe fabrication companies that specially deal with Grade 91 piping and fittings. There are a few in the US - Bendtec in Duluth,MN is one that we have used with great success.
RE: Heat Treatment A335 P91 Assistance
As per metengr, you do need to write a heat treating specification for the work, confer with the heat treater and determine the exact heat treating parameters to be employed and then follow through with surviellance and appropriate testing.