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Incoloy 800H (UNS 8810) PWHT

Incoloy 800H (UNS 8810) PWHT

Incoloy 800H (UNS 8810) PWHT

I fabricated 800H pipe welded with Inco 82 filler, performed stabilising annealing at 985 deg C for 3 hours.
Specified code is B31.3 and the service temperature is 850 deg C.
Client specifies a maximum cooling rate of 150 deg C/hr but we exceed this cooling rate. Actual cooling rate is 180 deg C/hr.
I looked up B31.3 and there is no requirement for cooling rate. ASME VIII says it up to agreement between user and manufacturer.
Basically we did not meet client's spec. but I would like to know if the increase in the cooling rate by 20 dec/hr is harmful to the welds before getting client to accept the weld as it is.
If these welds are rejected, can I repair them by going through another cycle of heat treatment?


RE: Incoloy 800H (UNS 8810) PWHT

I don't see any concern with this material. You need to discuss with the client because perhaps they were concerned with thermal stress. Yes, you can go another PWHT cycle.

RE: Incoloy 800H (UNS 8810) PWHT

Agree with metengr. I have performed this type of PWHT numerous times with higher cooling rates than required by your client without adverse incident.

RE: Incoloy 800H (UNS 8810) PWHT

Thanks meting and welstan.
Went back to look into the client spec. again and they cited stabilize annealing as the reason for the heat treating.
If this is the case, I would think a faster cooling is more beneficial.

RE: Incoloy 800H (UNS 8810) PWHT

The faster cooling could contribute to higher residual stresses, but your cooling rate was not extremely fast.
IF they balk at accepting it just re-HT

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

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