From Your photos, the seal looks like it is made from either (a) sintered/compacted iron/graphite/copper mix; or (b) is a pure sintered/compacted graphite material... and was intended for high temp service.
It would pay to have the material analyzed by a lab. There might be a material standard IF the material can be verified.
As far as a industry standard for the shape and material... I doubt it. HOWEVER... The following specs MIGHT actually provide a clue after-all.
SAE AIR1077 Metallic Seal Rings for High Temperature Reciprocating Hydraulic Service
MIL-M-24130 and /1, /2 and /3 METALLIC SEAL RINGS, NON-INTEGRAL GENERAL SPECIFICATION FOR [spec is distribution controlled by Navy]
NOTE.
All metallic seals/gaskets I found were hollow and crushed/distorted on installation.
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
here is a rough CAD presentation.
the "washer" is made from CRES.
the backside has approx 1 degree bevel.
no o-ring or others, METAL TO METAL sealing for 3000 psi system.
thanks.
