GOST 12836 FLANGE tells you that most flange gaskets are cut from non-metal plates, or made to specified dimensions by professional factories, and their materials are asbestos rubber sheets, asbestos sheets, polyethylene sheets, etc.

GOST 12836 FLANGE tells you that there are also metal-clad flange gaskets made of thin metal plates (white iron, stainless steel) wrapped around non-metallic materials such as asbestos; there is also a thin steel strip and asbestos strip wound together of spiral wound gaskets.
GOST 12836 FLANGE tells you that ordinary rubber gaskets are suitable for applications where the temperature is lower than 120℃; asbestos rubber gaskets are suitable for applications where the temperature of water vapor is lower than 450℃, the temperature of the oil is lower than 350℃, and the pressure is lower than 5MPa, For general corrosive media, the most commonly used is the acid-resistant asbestos board.
The above information is the GOST 12836 FLANGE manufacturer's introduction and analysis of the different materials of the flange, hope it helps you.