Calucating post weld for P91
Calucating post weld for P91
(OP)
I'm trying to create a procedure for welding P91. I can't find any method to calculate the "bake-out" temp and time. I figure the temp will equal the preheat temp.
Here is a quote from Robert Swanekamp, PE, HRSG User's Group.
"A post-weld hydrogen bake, at 600 F for a minimum of 20 minutes, at least three inches on each side of the weld."
Is there a formula or rule to calucate bakeout time? Is 20 minutes @ 600 F adequate? How does wall thickness affect this hold time?
jimwaa
Here is a quote from Robert Swanekamp, PE, HRSG User's Group.
"A post-weld hydrogen bake, at 600 F for a minimum of 20 minutes, at least three inches on each side of the weld."
Is there a formula or rule to calucate bakeout time? Is 20 minutes @ 600 F adequate? How does wall thickness affect this hold time?
jimwaa





RE: Calucating post weld for P91
Bake out procedure for this joint would be 500 deg F minimum for 2 hours (1 hour/inch of nominal thickness). The time duration serves to two purposes; to provide for a uniform temperature gradient through wall and to diffuse hydrogen atoms.
RE: Calucating post weld for P91
Or
Should it be air cooled to room temp from 450F, uncontrolled?
jimwaa
RE: Calucating post weld for P91
RE: Calucating post weld for P91
RE: Calucating post weld for P91
RE: Calucating post weld for P91