The sealing surface is the valveThe more critical working surface, the quality of the sealing surface directly affects the service life of the valve, and 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 valve sealing surface materials:
“Corrosion” is the process in which the sealing surface is damaged under the action of the medium. If the surface is damaged in this way, the tightness cannot be guaranteed, therefore, the sealing surface material must be resistant to corrosion. The corrosion resistance of a material mainly depends on the strength of the material and its chemical stability.
“Scratching” is the damage to the material caused by friction during the relative movement of the sealing surfaces. This damage will inevitably lead to the destruction of the sealing surface, therefore, the sealing surface material must have good anti-scratch performance, especially for gate valves. The scratch resistance of a material is often determined by the internal properties of the material.
“Erosion” is the process in which the sealing surface is damaged when the medium flows through the sealing surface at high speed. This kind of damage is more obvious in the throttle valve and safety valve used in the high temperature and high pressure steam medium, which has a great influence on the sealing damage. Therefore, erosion resistance is also one of the important requirements of the sealing surface material.
④ It should have a certain hardness, and the hardness will decrease greatly at 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 sealing ring, so as to avoid extra stress and loosening at high temperature.
⑥ When used under high temperature conditions, there must be sufficient anti-oxidation, thermal fatigue resistance and thermal cycling.
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.