From www.gasketwiki.com
A gasket material that is comprised of asbestos fibers encapsulated within a rubber binder. This type of gasket is tough, durable and dimensionally stable, relatively incompressible and exhibits low creep characteristics. It also has the ability to effectively form a seal over a wide range of service conditions which has given it a good reputation. Compressed asbestos fiber(CAF) gaskets have good chemical resistance capabilities and a good working temperature range of cryogenic to 1,100F. It is less suitable for low bolt loads such as use with non-metallic flanges and low grade bolts, and is not suitable for use in stainless steel flanges due to its chlorine content which will damage the flanges. However, CAF gaskets can be installed relatively easily due to their ability to handle mechanical abuse, incorrect fitting and bolt-load retorquing.
Current industry practices have almost completely abolished the use of an compressed asbestos gasket material and have more over to the safer alternative of the Compressed Synthetic Fiber Gasket Material (CSF).
Material
Sprial Wound Gasket with Asbestos Filler
The asbestos material used in this type of gasket acts as a reinforcing component that is binded together with a lower percentage of an elastomer. The chrysotile 'white' asbestos is the safest of the asbestos fibers. It is a combination of long, hollow fibers with branches/hairs which impart a high strength characteristic when the fibers are interlocked. The material is mined in abundance in Canada, Russia and Africa.
Health & Legal Concerns
Use of these gaskets has greatly reduced due to health and legal concerns involving airborne asbestos fibers and their role in causing Mesothelioma (a type of cancer), Asbestosis (a scarring of the lung tissue), and lung cancer. However, CAF gaskets are still used extensively in Canada due to their excellent gasket properties and low cost in comparison to other more modern gasket materials. Finished gaskets and CAF sheet material is considered safe, but care must be taken to avoid releasing harmful fibers when sanding, sawing or grinding new and used gaskets.
