The Factors to consider when selecting a gasket
Operating temperature and pressure, pipe size, temperature cycle, cost, chemical composition of fluid, fire resistance, radiation, etc
In general of application, please use Pressure – Temperature chart as below for understanding the capability of each type of gasket.
Sheet Gasket (Rubber gasket, Non-asbestos gasket, PTFE gasket, flexible graphite gasket)
Rubber gasket is common with black color, but it is different.
Compressed Synthetic Fiber Gasket (e.g. non asbestos or asbestos free)
PTFE (Poly Tetra Flour Ethylene) Gasket
Type: Virgin(Pure), Filled (Compressed Synthetic), Micro-cellular (Closed or Expanded), with thin metal reinforcement.
Flexible Graphite Gasket
Type: Pure Graphite flake, Laminate graphite on thin metal sheet
Features: Made of pure graphite without bonding agent through a special manufacturing process, high compression, resistance, temperature resistance, etc.
Disadvantages: Unreinforced natural graphite is fragile and tends to stick to the flange surface.
Spiral Wound Gaskets
Spiral Wound Gaskets are suitable for a wide range of operating conditions and can be adapted to suit almost all applications. The Gaskets can seal fluid pressures up to 250 bar and temperature range of -200oC to 1000oC.
The Gasket is easy to install and remove and will not cause damage to the Flange surfaces. A combination of winding materials and metals are available which enable the Gasket to meet the requirements of varied operating conditions.
For Metal O-ring, see this article: Flange Face Types, RTJ