According to jim rozen :
In article , Harold and Susan Vordos says...

You're on your own where seals are concerned, but I think I'd research
various O ring compounds. Surely one of them would suit your needs.

He'd be crazy to use elastomer O-rings when commercial conflat
flanges are there.

They use a flat OFHC gasked which is trapped between two stainless
knife edges. They will withstand high temperatures, low temperatures,
and unless the thick flat copper gasket completely rots away are
quite long-lasting I would think.

But bear in mind that the gaskets *must* be replaced every time
you open it for inspection. So -- be sure to stock enough gaskets to
deal with the inspection schedule, as replacements may not be available
one hundred years or so down the line.

The O-rings, however, can probably be re-used some number of
times -- if you can find a material which satisfies your other
requirements.

Enjoy,
DoN.
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