Seven Factors Influencing Gasket and Packing Seal

Author:     Published time:2016-10-13 10:25     Reading times:1083    

The factors that affect the gasket and packing seal are as follows:

1. The sealing surface of the surface conditions: the shape of the sealing surface and surface roughness on the sealing have a certain influence, smooth surface is conducive to sealing. Soft gaskets are not sensitive to surface conditions due to their ease of deformation, while for hard gaskets the surface condition is highly affected.

2. The sealing surface of the contact width: the sealing surface and the gasket or packing the greater the width of the contact, the fluid leakage through the longer the path, the greater loss of flow resistance, which is conducive to sealing. But under the same pressing force, the contact width is bigger, then the sealing specific pressure will be reduced. Therefore, according to the material of the seal to find the appropriate contact width.

3. The nature of the fluid: the viscosity of the liquid and gasket packing has a great impact on the large viscosity of the fluid because of its poor mobility and easy to seal. Liquid viscosity is much larger than the gas, which is easier to seal the liquid than the gas. Saturated steam, because it will condense out droplets and block the leakage between the sealing surface of the channel, which is easier than super heated steam seal. The larger the molecular volume of the fluid, the easier it is to be blocked by a narrow sealing gap, which makes it easier to seal. Liquid on the sealing material of the infiltration of the seal also has an impact. Easy to infiltrate the liquid, due to the gasket and the capillary internal capillary pores and easy to produce leakage.

4.The temperature of the fluid: the temperature of the high and low liquid viscosity, which has an impact on the seal. Temperature, liquid viscosity decreased, also increased gas viscosity. On the other hand, a change in temperature often causes deformation of the seal assembly and tends to cause leakage.

5 The gasket and filler material: soft material due to its loading force is easy to produce elastic or plastic deformation, thereby blocking the fluid leakage channel, which is conducive to sealing; but soft materials generally can not withstand the role of high-pressure fluid . Sealing material corrosion resistance, heat resistance, compactness and so have a certain impact on the seal.

6 The sealing surface than the pressure: between the sealing surface of the unit normal force on the contact surface, said sealing than the pressure, the size of the sealing surface than the pressure is an important factor in the gasket or packing sealing. Typically, by applying a pre load force on the sealing surface to produce a specific pressure, the seal deformation to reduce or eliminate the gap between the sealing contact surface to prevent the passage of fluid to achieve the purpose of sealing. It should be noted that the effect of the fluid pressure causes the sealing surface to vary in specific pressure. The increase of the pressure ratio of the sealing surface is favorable for sealing, but it is limited by the compress strength of the sealing material. For the dynamic sealing, the increase of the specific pressure of the sealing surface will cause the corresponding increase of the frictional resistance.

7. The impact of external conditions: vibration of the piping system, the connection components of the deformation, the installation position of the offset and other reasons will have additional force on the seal, which will adversely affect the seal. Especially vibration, will make the sealing surface of the compression force between the cyclical changes in the connecting bolt relaxation, resulting in sealing failure. The cause of the vibration may be external, it may be due to fluid within the system caused by the dynamic. To make the seal reliable, we must carefully consider the above factors, and the manufacture and selection of gaskets and packing is essential.