Heat treatment of the Flare tip with CS A350 LF2 flange and UNS08330 body

[lekfn]

Good day,

We are applying Ceramic coating to one of the our flare tip. Ceramic coating requires sintering at 800 degC for 1 hour.
Flare tip is basically pipe with flange: 42" carbon steel A350 LF2 flange and body UNS08330 (L-3m, OD-1m, Wall thickness 10mm).
Per ASME yield strength of the CS A350 LF2 approaching to 0 after 400 degC, however PWHT is generally done at about 600 degC.

Our concern that CS flange may deform under 800 degC heat treatment.

Does someone has similar experience we can apply here?
Or any method to do heat treatment safe for flange?

Thanks!
Dulat

 

[metengr]

Yes, as I understand your question, can you remove the CS flange and sinter the ceramic coating on the body (UNS08330)? When this step is completed, re-attach the CS flange.

 

[racookpe1978]

But it is a flare tip - on the end of a cantilevered load (stack pipe) extending into ??? - well, essentially nothing.

So, if the flange is removed (I assume it is there to support the "roundness" of the end of the open pipe under years of very high temperature exposure to heat levels that would soften and warp the opening into a crimped (reduced area) for the outlet gases. But otherwise, there are no forces on the tip of the stack pipe.

So remove the flange, apply the ceramic as above, and heat the pipe tip to seal the ceramic (to prevent erosion/corrosion ?) and then re-attach the flange around the newly-sintered ceramic coating. Be careful not to crack the ceramic when re-attaching the flange. That would be your threat to the ceramic.