The cause of sealing surface damage can be summarized as follows.
Damage to the sealing surface of man-made damage and natural damage to two. Man-made damage, because of poor design, manufacturing is not refined, improper selection, installation is not correct, poor use and poor maintenance and other factors. Natural damage, the valve
is the normal work of the wear and tear, is the medium of the sealing surface erosion and erosion, such as the inevitable damage.
Mechanical damage, the sealing surface in the opening and closing over we will produce abrasions, bumps, crushes and other damage. Between the two sealing surfaces, under the action of high temperature and pressure of mutual penetration of atoms oozing, resulting in adhesion phenomenon. When the two sealing surfaces move with each other, the adhesion easily tear. The higher the surface roughness of the sealing surface, this phenomenon more easily. Valve in the closed process, the valve seat in the back seat process will bump and squeeze the sealing surface, the sealing surface of local wear or indentation.
Media erosion, which is the media activities of the sealing surface wear, flushing, cavitation results. Medium at a certain speed, the medium of floating fine particles in violation of the sealing surface, causing local damage, high-speed activities of the media directly flush the sealing surface, causing local damage, mixed media and local vaporization, impact seal surface, causing local damage. The erosion of the media plus chemical erosion alternately, will be a strong erosion sealing surface.
Electrochemical corrosion, sealing surface contact with each other, the sealing surface and the closed body and the valve body contact and the concentration of the medium difference, oxygen concentration and other reasons, will produce a potential difference, the electrochemical erosion, resulting in anode side sealing surface erosion.
The chemical erosion of the medium, the sealing surface of the medium in the vicinity of the current does not produce the case, the media directly with the sealing surface from the chemical effect, erosion sealing surface.
Improper installation and maintenance led to the sealing surface is not working properly, the valve sick operation, prematurely damaged the sealing surface.
Improper selection and manipulation caused by damage. Mainly in the absence of conditions according to the premise of the use of valves
, the use of cut-off valve when the throttle, resulting in closed than the pressure is too large and closed too fast or closed, so that the sealing surface erosion and wear.
Sealing surface quality is not good, mainly in the sealing surface cracks, porosity and crumbs and other defects, is due to improper selection of welding and heat treatment specifications and welding and heat treatment caused by poor handling, the sealing surface hard over high Or too low, because of material selection errors or improper heat treatment caused by uneven sealing surface hardness, intolerance erosion, mainly due to the surfacing process will be the bottom of the metal blowing to the above, dilute the sealing surface alloy components caused by of. Of course, there is also a design problem.