1. Metallic gaskets
There are three main types:
(1)Octagonal and oval gaskets. They are suitable for the flange sealing surface with trapezoidal grooves.
(2)Gaskets with the tooth profile. The conical tooth ripple is machined on the sealing surface of metal flat gaskets, suitable for the male and female flange faces.
(3)Lens gaskets-suitable for lens flange sealing surfaces. Metallic gaskets are made from pure iron, dead mild steel, stainless steel, aluminum and other materials.
High Requirements are on the machining precision and surface roughness of the sealing surface of metallic gaskets, and the bolt has great pressing force, so the gasket is used for high temperature and high pressure valves.

2. Metal-clad graphite gaskets
Generally, they are used for the male and female flange faces and suitable for valves with higher temperature and pressure.

3. Spiral wound gaskets
They are formed by mixing and winding wave metal belts and sealing tapes. There are steel belts-asbestos, steel belts-polytetrafluoroethylene, steel belts-flexible graphite, etc. Generally, the gaskets are used for male and female flange faces and suitable for high temperature and medium pressure valves.

4. Teflon gaskets
They are mainly used for tongue-and-groove sealing surfaces and made from PTFE and PTFE with glass fibers. They are suitable for strong corrosive media in low temperature with various pressures.

5. Graphite gaskets
Flat gaskets made from soft graphite are suitable for high temperature and strong corrosive media.

6. Paronite gaskets
They are applicable to smooth flange sealing surfaces, male and female flange faces and tongue-and-groove flange faces. The advantages are good corrosion resistance and thermal stability, good plasticity, and small pressing force to ensure sealing. The disadvantage is low strength and easy adhesion to the flange sealing surface. Paronite gaskets include asbestos boards, anti-corrosion asbestos boards. Usually, the gaskets are made from asbestos boards, acid-resistant asbestos boards, oil-resistant asbestos boards, asbestos boards with metal wire and other materials. They are used for medium pressure valves in high temperature.