Based on the material, gaskets can be classified into three categories: non-metallic, metallic, and composite.

Non-metallic gaskets primarily include rubber sheets, asbestos rubber sheets, polytetrafluoroethylene (PTFE) sheets, and laminated glass fiber-reinforced PTFE sheets. Rubber sheets exhibit good elasticity and sealing performance, as well as corrosion resistance, but their application range is limited by pressure (below 16 MPa) and temperature (below 120°C) constraints. Asbestos rubber sheets can withstand temperatures up to 400°C and pressures of 64 MPa, and can be formulated for use with different media such as acids, alkalis, and oils. PTFE sheets offer excellent sealing performance and chemical stability, making them suitable for highly corrosive media, but their low temperature resistance (below 170°C) limits their application range. The use temperature of laminated glass fiber-reinforced PTFE sheets can reach 280°C, and adding copper powder or other metal powders can increase this to 380°C.

Metallic gaskets (rings) come in shapes such as trapezoidal, oval, prismatic, triangular, and serrated. They are suitable for sealing flammable, explosive, high-temperature, and high-pressure media, offering good sealing performance and high stability.

Composite gaskets are made of both metallic and non-metallic materials. They combine the high-temperature and high-pressure performance of metallic materials with the flexibility and elasticity of non-metallic materials. Composite gaskets include spiral wound gaskets, encapsulated gaskets, and combination gaskets. Spiral wound gaskets consist of corrugated metal strips and non-metallic strips (such as asbestos paper, graphite, or PTFE) of different materials, providing good elasticity and sealing performance. They are suitable for a wide range of media (depending on the metal and non-metallic strips used) and generally withstand pressures of 40 to 100 MPa. They are one of the most widely used gaskets in China.

Encapsulated gaskets are non-metallic sealing materials covered with metal plates. They combine the advantages of spiral wound gaskets with the feature that the non-metallic sealing material does not come into contact with the media. The metallic materials used in encapsulated gaskets include pure iron, mild steel, and stainless steel, while the non-metallic materials include asbestos, PTFE, glass fiber, etc.

Combination gaskets are made by overlaying non-metallic sealing materials with metal springs on metal plates (of the same material or different materials). The metal springs enhance the elasticity and sealing performance of the gaskets. They are suitable for high-pressure media that are flammable, explosive, toxic, or highly corrosive.