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Knowledge summary of PTFE gasket

Yangzhong Tianyou Seals Co.,Ltd | Updated: Dec 06, 2017

If PTFE gasket is not used properly, it will cause the leak, so how should the PTFE gasket be used correctly?

PTFE gasket can solve the chemical corrosion of the gasket by adjusting the formula and changing the material combination of the gasket. This kind of gasket has good compression and rebound performance, has multiple seal and certain self tightening functions, and can partially eliminate the influence of pressure, temperature change and mechanical vibration.

PTFE gasket is easy to repair and replace the surface of the flanges without bonding. It can keep its excellent sealing performance under high temperature, low temperature, high vacuum, shock vibration and other cyclic alternating and various harsh conditions.

PTFE gasket is suitable for sealing parts where temperature and pressure change violently. It is a static sealing element for pipes, valves, pumps, heat exchangers, towers, Manholes, hand holes and other flange connections. By changing the tension force of winding steel strip, the density and hardness of spiral wound gasket can be changed to meet the needs of various application parts. It is widely applied in petrochemical, mechanical, electric power, metallurgy, shipbuilding, medicine, atomic energy and aerospace industries.

Problems needing attention in the sealing of PTFE gasket:

1, the material of the gasket: soft material is easy to produce elastic or plastic deformation due to its preload force, thus blocking the channel of fluid leakage, so it is good for sealing, but soft materials generally cannot withstand the action of high pressure fluid. The corrosion resistance, heat resistance and density of the gasket material have some influence on the seal.

2, the temperature of the sealed medium: the temperature of the medium fluid will directly affect the sealing performance of the backing plate, so the material selection must be equal to or higher than the field temperature. Furthermore, the change of temperature will directly affect the sealing performance of the backing plate, resulting in leakage.

3, the media fluid: the role of seals is to seal the medium, prevent leakage. In order to better play a role of sealing, we must take into account the temperature, pressure, pH value, corrosion and other factors.

4, the size of the sealing surface: the larger the contact width between the gasket and the sealing surface, the longer the path of the medium leakage is, but under the same compression force, the larger the contact width is, the lower the seal specific pressure will be. Therefore, the suitable contact width should be sought according to the material condition of the seal.

5. The surface condition of the sealed surface: the shape of the sealing surface and the surface roughness have a certain influence on the sealing, and the smooth surface is beneficial to the seal. The soft gasket is insensitive to the surface condition because of its easy deformation, and the surface condition is greatly affected to the hard gasket. The greater the contact width between the sealing surface and the gasket or filler, the longer the path to pass through the leakage of the fluid, the greater the flow resistance loss, which is beneficial to the seal. But under the same compression force, the larger the contact width is, the seal ratio will be reduced. Therefore, the suitable contact width should be sought according to the material condition of the seal.

6, the influence of external conditions: the vibration of pipeline system, the deformation of connection components and the offset of installation position will cause additional force on seals, which will cause adverse effects on sealing. In particular, the vibration will make the pressing force between the seal face periodically change, make the connecting bolt relax, and cause the seal failure. The cause of vibration may be external and may also be caused by the fluid movement within the system. If you want to get a good seal, we must take these factors into consideration.