Because of the functions of sealing elements on the valve channel, such as cutting and connecting, adjusting and distributing, separating and mixing media, the sealing surface is often corroded, eroded, and worn by the media, making it highly susceptible to damage. There are two reasons for damage to the sealing surface: human damage and natural damage. Human damage is caused by factors such as poor design, poor manufacturing, improper material selection, improper installation, poor use, and poor maintenance. Natural damage refers to the wear and tear of the valve under normal working conditions, which is inevitably caused by corrosion and erosion of the sealing surface by the medium.
 
The reasons for the damage to the sealing surface can be summarized as follows:
1. Poor processing quality of sealing surface
It mainly manifests in defects such as cracks, pores, and slag inclusions on the sealing surface, high or low hardness of the sealing surface, uneven hardness of the sealing surface, and poor corrosion resistance.
 
2. Damage caused by improper selection and poor operation
The main manifestation is that the valve was not selected according to the operating conditions, and the block valve was used as a throttle valve, resulting in excessive closing pressure, too fast or not tight closing, and causing erosion and wear on the sealing surface.
 
3. Chemical corrosion of media
The medium around the sealing surface, without generating current, directly reacts with the sealing surface and corrodes it.
 
4. Erosion of media
It is the result of wear, erosion, and cavitation of the sealing surface when the medium flows. At a certain speed, the floating fine particles in the medium collide with the sealing surface, causing partial damage. The high-speed flowing medium directly washes the sealing surface, causing partial damage. When the medium is mixed and partially vaporized, bubbles explode and impact the sealing surface, causing partial damage.
 
5. Mechanical damage
In the opening and closing process, the sealing surface may be damaged by scratches, bumps, and squeezing. Under the action of high temperature and pressure, atoms penetrate each other between the two sealing surfaces, resulting in adhesion. When the two sealing surfaces move towards each other, the adhesive area is prone to tearing.
 
6. Fatigue damage
During long-term use, the sealing surface may experience fatigue, cracks, and delamination under alternating loads. After long-term use, rubber and plastic are prone to aging, leading to poor performance.
 
From the analysis of the causes of damage to the sealing surface above, it can be seen that in order to improve the quality and service life of the valve sealing surface, it is necessary to choose appropriate sealing surface materials, reasonable sealing structures, and processing methods.