For extreme temperature and/or aggressive chemicals, graphite gasket sheet material is often the answer. Graphite is soft, compressible, and conforms readily to imperfections in the faces of flanges or other surfaces being sealed. Hennig Gasket & Seal can supply flexible graphite sheet from manufacturers like Pyrotek in sizes up to 60” square and thicknesses from 1/32” to ¼”. (Thicker graphite is available on request.)
Graphite gasket material is almost pure carbon with the atomic structure arranged to form a soft, slippery material. To increase strength and reduce creep, graphite is often laminated with steel foil, wire mesh or stainless steel “tang” material. (Tangs are little hooks stamped into the steel that help hold the graphite layers in place.)
Thickness: 1/32” to ¼”
Temperature Range: 400°F to 750°F
When there’s oxygen present, (which is most applications,) graphite is usable over temperatures from 400 to 750 °F. In a non-oxidizing atmosphere it can go as high as 5,432 °F.
Graphite is unaffected by almost all chemicals, no matter how corrosive and regardless of pH. Those that will attack it are highly oxidizing acids like nitric and sulfuric acid. It’s also resistant to steam, which makes it a popular choice in steam systems and operations where steam cleaning is undertaken.
A major application limitation of graphite gasket sheet material is that it cannot be used with products intended for human consumption. This is because there’s a risk of graphite particles being incorporated into the media being sealed against. Consequently, there are no FDA or NSF-approved forms of graphite.