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The causes of damage to the valve sealing surface

Release time:

Jul 02,2024

As the seals in the valve channel plays a cut-off and through, regulation and distribution, separation and mixing of media and other roles, so the sealing surface is often subject to media corrosion, erosion, wear and tear, very easy to damage. Sealing surface damage caused by man-made damage and natural damage of two kinds. Man-made damage, is due to poor design, manufacturing is not refined, improper selection of materials, installation is not correct, the use of bad and maintenance and other factors. Natural damage, is the normal working condition of the valve wear, is the medium of the sealing surface of the inevitable corrosion and erosion and other damage caused by the damage.

As the seals in the valve channel plays a cut-off and through, regulation and distribution, separation and mixing of media and other roles, so the sealing surface is often subject to media corrosion, erosion, wear and tear, very easy to damage. Sealing surface damage caused by man-made damage and natural damage of two kinds. Man-made damage, is due to poor design, manufacturing is not refined, improper selection of materials, installation is not correct, the use of bad and maintenance and other factors. Natural damage, is the normal working condition of the valve wear, is the medium of the sealing surface of the inevitable corrosion and erosion and other damage caused by the damage.

   The causes of damage to the valve sealing surface can be summarised as follows:

   1、Poor quality of sealing surface machining

Mainly manifested in the sealing surface cracks, pores and ballast and other defects, because of surfacing and heat treatment specification selection and surfacing and heat treatment process caused by poor operation, sealing surface hardness is too high or too low, is due to the selection of the material is not the right or heat treatment caused by improper, uneven hardness of the sealing surface, corrosion resistance, mainly due to the process of surfacing will be blown to the top of the bottom layer of the metal to dilute the sealing surface alloy components Caused by the alloy composition of the sealing surface. Of course, there is also a design problem.

   2、Damage caused by improper selection and poor operation

Mainly in the absence of working conditions selection of valves, the cut-off valve as a throttle valve use, resulting in excessive closing pressure and close too quickly or close poorly, so that the sealing surface by erosion and wear. Incorrect installation and poor maintenance leads to the sealing surface is not working properly, the valve with disease operation, premature damage to the sealing surface.

   3、Chemical corrosion of the medium

   The medium around the sealing surface in the case of not generating current, the medium directly with the sealing surface of the chemical action, corrosion of the sealing surface. Electrochemical corrosion, sealing surface contact with each other, the sealing surface and the closing body and the valve body contact, as well as the media concentration difference, oxygen concentration difference and other reasons, will produce potential difference, electrochemical corrosion occurs, resulting in the anode side of the sealing surface is corroded.

   4、Erosion of the medium

    It is the result of media flow on the sealing surface wear, scouring, cavitation. Medium at a certain speed, the floating particles in the medium impinge on the sealing surface, causing local damage, high-speed flow of the medium directly scouring the sealing surface, causing local damage, media mixing and local vapour, resulting in bubble bursting impact sealing surface, resulting in local damage. Medium erosion and chemical corrosion alternating effects, will be strongly corroded sealing surface.

    5、Mechanical damage

    Sealing surface in the process of opening and closing will produce abrasion, bruising, extrusion and other damage. Between the two sealing surfaces, atomic interpenetration occurs under the action of high temperature and high pressure, resulting in the phenomenon of adhesion. When the two sealing surfaces move each other, the adhesion is easy to pull tear. The higher the surface roughness of the sealing surface, the more likely this phenomenon occurs. Valve in the closing process, the valve flap in the process of back to the seat will touch and squeeze the sealing surface, so that the sealing surface of the local abrasion or indentation.

   6、Fatigue damage

    Sealing surface in long-term use, under the action of alternating loads, resulting in fatigue of the sealing surface, cracks and peeling layer. Rubber and plastic after long-term use, easy to produce aging phenomenon, resulting in poor performance.

   From the above analysis of the causes of damage to the sealing surface can be seen, in order to improve the quality and service life of the valve sealing surface, it is necessary to choose the appropriate sealing surface materials, reasonable sealing structure and processing methods.

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