The Reason For The Damage Of The Sealing Surface Of The Pneumatic Shut-off Valve

1. The processing quality of the sealing surface is not good: it is mainly manifested in the defects such as cracks, pores and ballast on the sealing surface, which are caused by improper selection of surfacing and heat treatment specifications and poor operation during surfacing and heat treatment. The hardness of the sealing surface is too high. High or too low is caused by incorrect material selection or improper heat treatment. The hardness of the sealing surface is uneven and it is not resistant to corrosion. Of course, there are design issues here as well.

2. Damage caused by improper selection and poor operation: mainly in that the valve is not selected according to the working conditions, and the shut-off valve is used as a throttle valve, which leads to excessive closing pressure and closing too fast or tight closing, which makes the sealing Surfaces are eroded and worn.

3. Improper installation and poor maintenance of the pneumatic shut-off valve lead to abnormal operation of the sealing surface, and the valve operates in a diseased manner, which prematurely damages the sealing surface.

4. Chemical corrosion of the medium: When the medium around the sealing surface does not generate current, the medium directly acts chemically with the sealing surface and corrodes the sealing surface.

5. Electrochemical corrosion: The contact between the sealing surfaces, the contact between the sealing surface and the closing body and the valve body, as well as the concentration difference of the medium, the oxygen concentration difference, etc., will cause a potential difference and electrochemical corrosion, which will cause the sealing surface on the anode side to be damaged. corrosion.

6. Erosion of medium: it is the result of wear, erosion and cavitation of the sealing surface when the medium flows. When the medium is at a certain speed, the floating fine particles in the medium collide with the sealing surface, causing local damage, and the high-speed flowing medium directly washes the sealing surface, causing local damage. surface, causing local damage. The erosion of the medium and the alternating action of chemical corrosion will strongly erode the sealing surface.

7. Mechanical damage: The sealing surface will be scratched, bruised, crushed and other damage when it is opened and closed. Between the two sealing surfaces, under the action of high temperature and high pressure, the atoms penetrate into each other, resulting in the phenomenon of adhesion. When the two sealing surfaces move to each other, the adhesion is easy to be pulled and torn. The higher the surface roughness of the sealing surface, the more likely this phenomenon occurs. During the closing process of the pneumatic shut-off valve, the valve disc will bruise and squeeze the sealing surface during the process of returning to the seat, causing partial wear or indentation of the sealing surface.

8. Fatigue damage: In the long-term use of the sealing surface, the Sanjing valve will cause fatigue on the sealing surface under the action of alternating loads, and cracks and peeling layers will appear. After long-term use, rubber and plastic are prone to aging, resulting in poor performance.