Very high temperature flange bolting

[AbyssUK]

Hello, I work in the research and development labs for a gasket manufacturer. I've been tasked with designing a new piece of equipment to test our gaskets in a 4" class 300 flange at least 800C (1472F).

Now I've looked at the materials guides for the asme flanges and it has some listed materials for use at these temperatures (inconel 800H SS 304H etc..) so I'll use one of these for the flange. However...

I need to select a bolting material, which can withstand the maximum possible ratings, I've been told Nimonic 80A would do the job but does anybody know of any other materials which would retain the maximum bolt load possible after heating to 800C?

Also just out of curiosity has anybody had any experience of using bolted flanges at or above 800C (1472F)? If so what materials did you use ?

Thanks in advance

AbyssUK

 

[MikeMet]

You might consider using Inconel 617 for the bolting. We have used in some high temp applications, but the bolt loads were not high.