1. Surface condition of sealing surface

The shape and surface roughness of the valve sealing surface have a certain impact on sealing performance, and a smooth surface is beneficial for sealing. Soft gaskets are prone to deformation and are not sensitive to surface conditions. For hard gaskets, the surface condition has a significant impact.

2. Contact width of sealing surface

The larger the contact width between the valve sealing surface and the gasket or packing, the longer the path for fluid leakage and the greater the flow resistance loss, which is beneficial for sealing. But under the same compression force, the larger the contact width, the smaller the sealing pressure.

3. Properties of fluids

The viscosity of liquids has a significant impact on the sealing performance of fillers and gaskets, and fluids with high viscosity are easy to seal due to their poor flowability. The larger the molecular volume of the fluid, the easier it is to be blocked by narrow sealing gaps, making it easier to seal. The wettability of the liquid to the sealing material also has a certain impact on the sealing. A liquid that is easy to soak is prone to leakage due to the capillary effect of the micropores inside the gasket and filler.

4. Temperature of fluid

The temperature affects the viscosity of the liquid, thereby affecting its sealing performance. As the temperature increases, the viscosity of the liquid decreases and the viscosity of the gas increases. On the other hand, changes in temperature often cause deformation of sealing components and are prone to leakage.

5. Material of gaskets and fillers

Soft materials are prone to elastic or plastic deformation under the action of preload, thereby blocking the passage of fluid leakage and facilitating sealing. However, soft materials generally cannot withstand the action of high-pressure fluids. The corrosion resistance, heat resistance, density, and hydrophilicity of sealing materials have a certain impact on sealing.

6. Sealing surface specific pressure

The normal force on the unit contact surface between sealing surfaces is called the sealing specific pressure, and the magnitude of the sealing surface specific pressure is an important factor affecting the sealing performance of gaskets or fillers. Usually, a certain specific pressure is generated on the sealing surface by applying pre tightening force, causing deformation of the sealing element to reduce or eliminate gaps between the sealing contact surfaces, preventing fluid from passing through, and achieving the purpose of sealing. Although an increase in the specific pressure of the sealing surface is beneficial for sealing, it is limited by the compressive strength of the sealing material.

7. External conditions influence

The vibration of the pipeline system, the deformation of the connecting components, the offset of the installation position and other reasons will produce additional force on the seals, which will adversely affect the seals.