What factors need to be taken into consideration when selecting valve sealing
Source：http://www.jmzkkj.comRelease Time：2018-06-04
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, the following factors should be considered when selecting the valve sealing surface material:
1. Corrosion resistance. "Corrosion" is the process of destruction of the surface of the sealing surface under the effect of the medium. If the surface is subjected to such damage, sealability cannot be guaranteed, and therefore, the sealing surface material must be resistant to corrosion. The corrosion resistance of a material depends mainly on the material and its chemical stability.
2. Anti-scratch. "Scratch" means that the material is damaged due to friction during the relative movement of the sealing surface. This damage will inevitably cause the destruction of the sealing surface, therefore, the sealing surface material must have good scratch resistance, especially the gate valve. The scratch resistance of a material is often determined by the internal properties of the material.
3. Erosion resistance. "Erosion" is the process in which the sealing surface is destroyed when the medium flows through the sealing surface at high speed. This kind of damage is more obvious in the high-temperature, high-pressure steam medium throttle valve, safety valve, and has a great influence on the sealing failure. Therefore, erosion resistance is also one of the important requirements of the sealing surface material.
4. There should be a certain degree of hardness and a large drop in hardness at the specified operating 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 looseness caused easily at high temperatures.
6. The use of high temperature conditions, there must be sufficient anti-oxidation, thermal fatigue resistance and thermal cycling and other issues.
In the current situation, it is difficult to find a sealing surface material that fully meets the above requirements, and can only meet the requirements of several aspects according to different types of valves and applications. For example, the valve used in high-speed medium should pay special attention to the erosion resistance of the sealing surface; when the medium contains solid impurities, the sealing surface material with higher hardness should be selected.
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