PTFE-coated gasket, also known as PTFE-coated gasket, is a non-metallic gasket, generally composed of two parts: a coating layer and an insert.
The cladding layer mainly plays the role of corrosion resistance, and is usually made of polytetrafluoroethylene material. The insert (filler) is a non-metallic sealing material with or without metal reinforcement layer with good elasticity, usually non-asbestos rubber gasket, Graphite composite gaskets and various rubber gaskets, in recent years, many customers have chosen to use metal corrugated gaskets as the inserts, or metal gaskets and asbestos-free rubber gaskets are used together.
PTFE-covered gaskets are mainly suitable for full-flat and raised-surface steel pipe flange connections, and are suitable for corrosive media with a nominal pressure PN of 0.6 to 5.0 MPa and a working temperature of -100 to 150 ℃ or for cleanliness. Media with higher requirements. Some containers, pipes and valve connections in the petroleum, chemical, pharmaceutical and food industries are often sealed with PTFE gaskets to ensure material cleanliness.
※ Note: Due to structural reasons, the PTFE of the cladding layer is thin, so it is prone to rupture during installation and use, causing the medium to penetrate into the core material in the embedded layer and cause erosion. Therefore, it is recommended to replace the gasket frequently or use modified tetrafluoro gasket or expanded tetrafluoro gasket in important sealing parts.
Performance characteristics of PTFE coated gasket
1. Combining the different characteristics of the lining core material and the corrosion resistance of PTFE
2. Low friction coefficient, not easy to bond, easy to install and disassemble
3. The product is clean and can be used for sealing parts such as food and medicine that are not allowed to contaminate
4. Good compression resilience
PTFE coated gasket using industry
Chemical, petrochemical, oil refining, chlor-alkali, acid production, phosphate fertilizer, pharmaceuticals, pesticides, chemical fiber, dyeing, coking, gas, organic synthesis, non-ferrous smelting, steel, atomic energy and high-purity product production (such as ionic membrane electrolysis), viscous materials Transportation and operation, food, beverage and other processing and production departments with highly stringent hygiene requirements.
Sealing parts of flange connections such as pipes, valves, pumps, pressure vessels, heat exchangers, condensers, generators, air compressors, exhaust pipes, refrigerators, etc.
Example of marking of PTFE-coated gasket
Sectional PTFE gasket with nominal diameter of 50mm and nominal pressure of 1.0MPa:
Machined PTFE gasket with nominal diameter of 50mm and nominal pressure of 1.0MPa:
Folding type PTFE gasket with nominal diameter of 50mm and nominal pressure of 1.0MPa:
Influence of External Conditions on PTFE Gaskets
The vibration of the piping system, the deformation of the connecting components, the offset of the installation position, etc., will generate additional forces on the seal, which will adversely affect the seal. In particular, vibration will cause periodic changes in the pressing force between the sealing surfaces, which will loosen the connecting bolts, resulting in seal failure. In order to achieve a good sealing effect, the following factors must be carefully considered:
1. The material of the gasket: the soft material EPTFE tetrafluoro gasket is easy to produce elastic or plastic deformation under the action of the pre-tightening force, thereby blocking the passage of fluid leakage, which is conducive to sealing; PTFE powder suppliers in india but soft EPTFE materials generally cannot withstand The role of high pressure fluids. Different gasket materials have different corrosion resistance, heat resistance, density, etc., and their applicable sealing media and working conditions are different.
2. The temperature of the place of use: the temperature of the medium directly affects the sealing performance of the PTFE gasket, so the material selection must be equal to or higher than the temperature of the on-site working conditions; sealing performance, resulting in leakage.
3. Sealing medium: In order to have a better sealing effect, the material of the sealing gasket must be selected according to the chemical properties of the actual sealing medium such as temperature, pressure, pH value, acidity and alkalinity.
4. The condition of the sealing surface: the shape and roughness of the sealing surface have a certain influence on the sealing performance, and the smooth surface is conducive to sealing.
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