Incoloy 800HT flange question - help!

[belfour30]

I realize there isn't any data for CL-150 flanges above 1000F. At very low pressures (20psi) - is there any reason I cannot use an incoloy 800H/HT flange (N08810) around 1500F?

Flange and attached pipe will all be solution annealed at 2100F.

Thanks!

 

[metengr]

belfour30;
Because the maximum working pressure for a Class 150 flange for this material group is only 25 psig and that is at 1000 deg F, regardless if it is solution annealed. If you go higher in service temperature, you will have significant creep deformation and subsequent leaks with this flange, because the flange is not adequately reinforced.

Why don't you go to a Class 300 flange for N08800 and be done with it? At 1500 deg F, a Class 300 flange has a working pressure of 25 psig.

 

[belfour30]

Metengr,

Thanks for all of your great answers and info regarding my pressure vessel questions over the past few months! Are you available as a consultant offline? We have been working with an ASME shop for projects like these but lately they have been less inclined to respond to inquiries which is why I found this forum. I certainly don't mind posting questions here if you don't mind continuing to answer them

FYI the design already called for CL-150 flanges which is why I do not want to change it midstream. I was not aware of the 1000F limitation on this class for ALL materials. I've decided to go ahead with N08810 CL-300 flanges for 1500F and 35psi.