How do you choose the sealing method of the valve?
- KEPLER TEAM
- Jun 1, 2021
- 2 min read
The sealing surface is the most critical working surface of the valve. The quality of the sealing surface directly affects the service life of the valve. The material of the sealing surface is an important factor to ensure the quality of the sealing surface. Therefore, based on my past experience, the following factors should be considered when selecting valve sealing surface materials.
1. Corrosion resistance.
"Corrosion" refers to the process in which the sealing surface is damaged under the action of the medium. If the surface is damaged in this way, the sealing performance cannot be guaranteed. Therefore, the sealing surface material must be corrosion-resistant. The corrosion resistance of the material mainly depends on the extremeness of the material and its chemical stability.
2. Anti-abrasion.
"Scratch" refers to the damage caused by friction of the material during the relative movement of the sealing surface. This kind of damage will inevitably cause damage to the sealing surface. Therefore, the sealing surface material must have good scratch resistance, especially for gate valves. The scratch resistance of a material is often determined by the internal properties of the material.
3. Erosion resistance.
"Erosion" refers to the process of destroying the sealing surface when the medium flows through the sealing surface at high speed. This kind of damage is more obvious in throttle valves and safety valves used in high temperature and high pressure steam media, and has a great impact on the damage of sealing. Therefore, erosion resistance is also one of the important requirements for sealing surface materials.
4. There should be a certain degree of hardness, and the hardness will drop greatly under the specified working temperature.
5. The linear expansion coefficient of the sealing surface and the body material should be similar, which is more important for the structure of the inlaid sealing ring, so as to avoid excessive stress and loosening at high temperatures.
6. When used under high temperature conditions, there must be sufficient resistance to oxidation, thermal fatigue and thermal cycling.
Precautions
Under the current circumstances, it is difficult to find a sealing surface material that fully meets the above requirements. It can only meet the requirements of certain aspects according to different valve types and uses.
Valves used in high-speed media should pay special attention to the erosion resistance requirements of the sealing surface; when the medium contains solid impurities, the sealing surface material with higher hardness should be selected.
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