Around that temperature you break carbon-carbon bonds and all other bonds too meaning that there is nothing that can survive long even with additives etc. in there to protect the elastomer. Fluoroelastomers will come closest.
What type of environment is causing you to look for an isolation gasket at your temperature as at this temperature galvanic corrosion would a rarity..
As stated above your temperatures are way and above the elastomeric gasket range. The is the temperature where you would start looking for reinforced gasket material if any pressure is involve
The application is to isolate a stainless pipe from an Anvil (Grinnell) figure number 212 carbon steel clamp to prevent galvanic action.
All the data I have comes from the standard pipe support drawing for a particular pipe shoe. The physical application is very common for us to see, the temperature range is unusual.
The detail drawing was likely copied from a similar pipe shoe used on much cooler lines. The term "elastomer" was copied over with little regard for its appropriate use. The notes describing what the elastomer is supposed to accomplish have led me to believe that a woven fiberglass cloth ("Thermofab") will suffice.
Our company is frequently put into this type of situatuion due to "Copy - Paste" errors. To save time a draftsman will copy the closest detail he can find and modify dimensions or text as required (I've done it myself). Unfortunately draftsmen are not required to understand if certain types of materials are suitable for the new application.
We were lucky in that the client asked us to confirm if we could find material suitable for high temperature. To add to the confusion he incorrectly converted from 370 celcius to 600 farenheit. We referenced 600 F on our offer and someone else caught the discrepancy.
If someone can suggest an alternative to Thermofab I would be happy to hear it in any case.
Isn't there a product consisting of mica tape? I believe it is used for electrical insulation. Being a mineral / ceramic it would be amazing heat resistance and prevent your galvanic corrosion.
Here is the website of Ciogebi for the aforementiond Mica tapes.
Here are is he block type insulation used on pipe supports depending on you support configuration. Look around this site as they have a lot pipe support products.
