I have seen non asbestos gaskets get brittle when you get them to high temperatures and in steam service many times. The non-asbestos version of gaskets I feel have never lived up to the asbestos gaskets without giving up something. Sure, graphite can handle everything but it needs to be handled with care compared to the old asbestos sheet days.
Well I found this patent for a new non-asbestos gasket that explains why non asbestos gaskets do not work as well. Here is an excerpt:
"the amount of the organic fiber is limited usually to 5 to 15 wt %, because such an organic fiber has a fiber diameter larger than asbestos fiber and is inferior to asbestos fiber in heat resistance and steam resistance. Many inorganic fibers such as rock wool, carbon fiber, and glass fiber can also be used as a base fiber only to the extent of 10 to 30 wt %, because inorganic fibers are more rigid and their fiber diameters are larger as compared with the asbestos fiber. Many organic fibers are easily broken during mixing or forming."
Here is the link to the patent.
Well I found this patent for a new non-asbestos gasket that explains why non asbestos gaskets do not work as well. Here is an excerpt:
"the amount of the organic fiber is limited usually to 5 to 15 wt %, because such an organic fiber has a fiber diameter larger than asbestos fiber and is inferior to asbestos fiber in heat resistance and steam resistance. Many inorganic fibers such as rock wool, carbon fiber, and glass fiber can also be used as a base fiber only to the extent of 10 to 30 wt %, because inorganic fibers are more rigid and their fiber diameters are larger as compared with the asbestos fiber. Many organic fibers are easily broken during mixing or forming."
Here is the link to the patent.