A gasket is a material or combination of materials clamped between two separate members of a mechanical joint. Its function is to effect a seal between the flanges and maintain the seal for a prolonged period. The gasket must be capable of sealing the mating surfaces, impervious and resistant to the medium being sealed and able to withstand the application temperature and pressure.
Most non-metallic gaskets consist of a fibrous base held together or strengthened with an elastomeric binder. The combination of the binders and base chosen depends on the compatibility with components and the conditions of the sealing environment as well as the load bearing characteristics required for the application.