Valve sealing surface damage to the six major reasons

The sealing surface of the valve plays a vital role in the valve channel, such as cutting off and connecting, regulating and distributing, separating and mixing media. However, the sealing surface is extremely easy to damage, the damage causes are mainly the following six:
First, the sealing surface processing quality is poor
Seal surface cracks, pores and clamping ballast and other defects, usually due to surfacing and heat treatment specifications are not selected properly and the operation process is poor. Seal surface hardness is too high or too low, because the selection of material error or improper heat treatment. Seal surface hardness is not uniform, not corrosion resistance, mainly when surfacing metal is blown to the top, dilute the sealing surface alloy composition, here may also exist in the design of the problem.
Second, improper selection and operation of the damage caused by bad
If not in accordance with the conditions of the correct selection of valves, the cut-off valve as a throttle valve, will lead to the closure of the specific pressure is too large, closed too quickly or closed poorly, so that the sealing surface by erosion and wear. Incorrect installation and maintenance will make the sealing surface of the work is not normal, so that the valve with disease operation, thereby prematurely damaging the sealing surface.
Third, the chemical corrosion of the medium
In the absence of current, the medium around the sealing surface will be directly with the sealing surface of the chemical reaction, corrosion of the sealing surface. In addition, due to the sealing surface contact with each other, with the closing body and the valve body contact as well as the medium concentration difference, oxygen concentration difference and other reasons to produce potential difference, electrochemical corrosion will occur, so that the anode side of the sealing surface is corroded.
Fourth, the medium of the erosion
This is the result of media flow on the sealing surface wear, scouring and vapor corrosion. Floating particles in the medium at a certain speed in the sealing surface, will cause local damage; high-speed flow of the medium directly scouring the sealing surface, will also make it locally damaged; media mixing and local vaporization of the bubble burst will impact the sealing surface, resulting in local damage. Medium erosion and chemical corrosion alternating effects, will strongly erode the sealing surface.
Fifth, mechanical damage
Seal surface in the process of opening and closing there will be abrasions, bruises and injuries and other damage. Under the action of high temperature and high pressure, the two sealing surfaces will occur between the atomic interpenetration, resulting in the phenomenon of adhesion, when the sealing surface is moving each other, the adhesion is easy to pull the tear. The higher the surface roughness of the sealing surface, the more likely this phenomenon occurs. Valve closing process, the valve flap back to the seat will also touch and squeeze the sealing surface, so that the sealing surface of the local wear or indentation.
Sixth, fatigue damage
Sealing surface in long-term use, under the action of alternating loads will produce fatigue, cracks and stripping layer. Rubber and plastic after long-term use is easy to aging, resulting in poor performance.
In summary, to improve the quality and service life of the valve sealing surface, we must choose the appropriate sealing surface materials, reasonable sealing structure and processing methods.