Mechanical damage, the sealing surface in the opening and closing we will have scratches, bumps, crushing and other damage. Between the two sealing surfaces, under the action of high temperature and high pressure, atoms seep into each other to cause adhesion. When the two sealing surface to move each other, the adhesion Department easily pull tear. The higher the sealing surface roughness, the more likely this phenomenon. During the closing process of the valve, the valve flap will bruise and crush the sealing surface during the process of returning to the seat, so that the sealing surface is partially worn or impressed. Erosion of the medium, it is the media activities on the sealing surface wear, flushing, cavitation results. Media at a certain speed, the media in the fine particles of the conflict against the sealing surface, causing local damage, high-speed activities of the media directly flush sealing surface, causing local damage, mixed media and local vaporization, Impact sealing surface, causing partial damage. Erosion of the media combined with chemical erosion alternating role, will be a strong erosion of the sealing surface. Electrochemical attack, the sealing surface contact with each other, the sealing surface and the closure body and the valve body contact and the concentration of the media, oxygen concentration and other reasons, will have a potential difference electrochemical corrosion occurs, resulting in the anode side of the sealing surface is eroded. Medium chemical erosion, near the sealing surface of the medium in the absence of current conditions, the media directly with the sealing surface chemical role, erosion sealing surface. Improper installation and poor maintenance lead to the sealing surface is not working properly, the valve sick, premature damage to the sealing surface. Improper selection and damage caused by poor handling. Mainly in the absence of conditions based on the conditions selected valve, the cut-off valve when used as a throttle valve, resulting in the closure of the pressure is too large and closed too fast or lax closed, so that the sealing surface erosion and wear. The sealing surface processing quality is not good, mainly in the sealing surface cracks, pores and ballast and other defects, is due to improper selection of welding and heat treatment and welding and heat treatment process caused by poor handling, the sealing surface is too high Or too low, because of the wrong choice of materials or heat treatment caused by improper seal surface hardness, corrosion resistance, mainly because the bottom of the metal in the surfacing process to blow up, dilute the sealing surface alloy composition caused of. Of course, there are also design issues. Cause sealing surface damage can be summarized as follows. Sealing surface damage due to human damage and natural damage of two. Man-made damage, because of poor design, manufacturing is not refined, improper material selection, improper installation, poor use and maintenance and other factors caused. Natural damage, is the valve under normal wear and tear, is the media on the sealing surface of the erosion and erosion inevitable damage.