Incoloy 800H (UNS 8810) PWHT 2

[JXWu]

Hi,
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?

Thanks.

 

[metengr]

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.

 

[weldstan]

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

 

[JXWu]

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.
Regards.

 

[EdStainless]

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

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P.E. Metallurgy, Plymouth Tube