Selection of valve sealing surface materials

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This post was last edited by leo_0088 on 2017-7-14 at 13:18. The valve sealing surface is the most critical working surface of a valve; the quality of this sealing surface directly determines the service life of the valve. The material used for the sealing surface is an important factor in ensuring its quality. Therefore, when selecting a material for the valve sealing surface, the following points should be taken into consideration: the first one is corrosion resistance. Corrosion is the process by which the surface of a sealing surface is damaged as a result of exposure to certain media; if the surface is damaged in this way, the sealing performance cannot be ensured. Therefore, the material used for the sealing surface must be corrosion-resistant. The corrosion resistance of a material mainly depends on its composition and the chemical stability of the material itself. 　　The second aspect is resistance to abrasion, which refers to the damage to the sealing surface caused by friction during relative movement. Such damage inevitably leads to the deterioration of the sealing surface; therefore, the material used for the sealing surface must have good resistance to abrasion. This is especially true for gate valves, whose sealing mechanism relies on a gate for sealing. The scratch resistance of a material is often determined by its internal properties. 　　The third requirement is erosion resistance, which refers to the process by which the medium, as it flows over the sealing surface, causes damage to that surface. This type of damage is particularly evident in throttle valves and safety valves used in high-temperature, high-pressure steam environments, and it has a significant impact on the sealing performance. Therefore, erosion resistance is one of the important requirements for materials used in sealing surfaces. 　　Fourthly, it should have a certain degree of hardness, with no significant decrease in hardness at the specified operating temperature. 　　Fifthly, the linear expansion coefficients of the sealing surface and the body material should be similar; this is important for ensuring effective sealing, as it prevents the generation of additional stresses at high temperatures that could lead to loosening. 　　The sixth point is that when used under high-temperature conditions, there must be sufficient resistance to oxidation, thermal fatigue, and heat cycling.