Teflon gasket is a non-metallic gasket, which is generally composed of two parts, covering layer and embedded material.
The coating is mainly corrosion resistant, which is usually made by PTFE material. The inserts are non-metallic sealing materials with or without a metal reinforcement layer and have good elasticity. The inserts are usually asbestos-free rubber gaskets, graphite composite gaskets and various types of rubber gaskets. In recent years, there are also a lot of customers choose the embedded metal corrugated gaskets, or metal gaskets mixed with asbestos-free rubber gaskets.
Teflon packing gasket is mainly used for the connection of pipe flange made of full-planar and protruded steel. It is suitable for corrosive medium with nominal pressure PN of 0.6 ~ 5.0MPa and working temperature of -100 ~ 150 ℃ or medium with high requirements on cleanliness. In petroleum, chemical, pharmaceutical and food industries, ptFE gaskets are often used for sealing to ensure material cleanliness.
Performance characteristics of PTFE gasket
1. Combined with the different characteristics of the lining core board materials and the corrosion resistance of PTFE
2. Low friction coefficient, not easy to bond, easy to install and remove
3. The product is clean and can be used in food, medicine and other sealed parts that are not allowed to be contaminated
4. Good compressive resilience
The industries that PTFE gaskets are suitable for
Chemical, petrochemical, oil refining, acid production, phosphate fertilizer, pharmaceutical, pesticide, chemical fiber, dyeing, coking, gas, organic synthesis, non-ferrous smelting, iron and steel, atomic energy and high purity product production (such as ion membrane electrolysis), viscous material transport and operation, highly hygienic requirements of food, beverage processing and production departments.
An example of the tag for PTFE gaskets
Polytetrafluoroethylene gasket with nominal diameter of 50mm and nominal pressure of 1.0MPa:
S - 50-1.0 GB/T1304-1992
Machined PTFE gaskets of nominal diameter 50mm and nominal pressure 1.0MPa:
M - 50-1.0 GB/T1304-1992
Packed PTFE gasket with nominal diameter of 50mm and nominal pressure of 1.0MPa:
F - 50-1.0 GB/T1304-1992
Effects of external conditions on ptFE gaskets
The vibration of the piping system, the deformation of the connecting components, the deviation of the installation position and other reasons will exert additional forces on the sealing parts, thus adversely affecting the sealing. In particular, the vibration will cause periodic changes in the compression force between the sealing surface, which will cause relaxation of the connecting bolts and seal failure. To achieve a good sealing effect, the following factors must be carefully considered:
1. EPTFE gasket is easy to produce elastic or plastic deformation under the action of preloading. Thus EPTFE gasket will block the channel of fluid leakage, which is conducive to sealing. However, EPTFE materials generally cannot withstand high pressure fluids.So the corrosion resistance, heat resistance and density of different gasket materials are different, and the applicable sealing medium and working condition are different.
2, The temperature of the use place: the temperature of the medium directly affects the sealing performance of ptFE gasket, so the material must be equal to or higher than the working temperature on the site; Furthermore, the change of temperature will directly affect the sealing performance of the backing plate, resulting in the occurrence of leakage.
3, The sealing medium: in order to have a better sealing effect, must be in accordance with the actual sealing medium temperature, pressure, PH value, acid and alkaline chemical properties to choose the sealing gasket material.
4, The condition of the sealing surface: the shape and roughness of the sealing surface have a certain impact on the sealing. Smooth surface facilitates sealing.