Six reasons for valve sealing surface damage

Six reasons for valve sealing surface damage

There are two reasons for sealing surface damage: man-made damage and natural damage. Man-made damage is caused by factors such as poor design, poor manufacturing, improper material selection, improper installation, poor use, and poor maintenance. Natural damage is the wear of the valve under normal working conditions, and it is the damage caused by the inevitable corrosion and erosion of the sealing surface by the medium.

The reasons for the damage of the sealing surface can be summarized as follows:

1. The processing quality of the sealing surface is not good

It is mainly manifested in defects such as cracks, pores and inclusions on the sealing surface, which are caused by improper selection of surfacing welding and heat treatment specifications and poor operation in the process of surfacing welding and heat treatment. The hardness of the sealing surface is too high or too low, which is due to incorrect material selection. Or caused by improper heat treatment, the hardness of the sealing surface is uneven, and it is not resistant to corrosion, mainly because the underlying metal is blown to the top during the surfacing process, which dilutes the alloy composition of the sealing surface. Of course, there are also design issues here.

2. Damage caused by improper selection and poor operation

The main performance is that the valve is not selected according to the working conditions, and the cut-off valve is used as a throttle valve, resulting in excessive closing specific pressure and too fast or lax closing, causing erosion and wear on the sealing surface.

Improper installation and poor maintenance lead to abnormal working of the sealing surface, valve operation with disease, and premature damage to the sealing surface.

3. Chemical corrosion of the medium

When the medium around the sealing surface does not generate current, the medium directly reacts with the sealing surface and corrodes the sealing surface. Electrochemical corrosion, the contact between the sealing surfaces, the contact between the sealing surface and the closing body and the valve body, the concentration difference of the medium, the oxygen concentration difference, etc., will generate a potential difference and electrochemical corrosion will cause the sealing surface on the anode side to be corroded.

4. Erosion of medium

It is the result of wear, erosion and cavitation of the sealing surface when the medium flows. When the medium is at a certain speed, the floating fine particles in the medium collide with the sealing surface, causing local damage. The high-speed flowing medium directly scours the sealing surface, causing local damage. When the medium is mixed and partially vaporized, air bubbles burst and impact the seal. surface, causing localized damage. The erosion of the medium and the alternating action of chemical corrosion will strongly erode the sealing surface.

5. Mechanical damage

During the opening and closing process, the sealing surface will be damaged by scratches, bruises, squeezes, etc. Between the two sealing surfaces, atoms penetrate each other under the action of high temperature and high pressure, resulting in adhesion phenomenon. When the two sealing surfaces move relative to each other, the adhesion is easy to tear. The higher the surface roughness of the sealing surface, the more likely this phenomenon will occur. During the closing process of the valve, the valve disc will bruise and squeeze the sealing surface during the process of returning to the seat, which will cause partial wear or indentation on the sealing surface.

6. Fatigue damage

During the long-term use of the sealing surface, under the action of alternating load, the sealing surface will be fatigued, cracks and peeling layers will appear. Rubber and plastics are prone to aging after long-term use, resulting in poor performance.

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

WESDOM Group specializes in pipeline fluid systems: R&D, production and sales of valves, pipe fittings, water meters, flow meters, etc. The products cover cast iron, cast steel, stainless steel, copper, plastics and other materials, which are widely used in hydropower stations, heat, buildings, Water supply and drainage, petroleum, chemical industry, electric power, medical and other fields.

Why more and more customers are choosing wesdom valves:

1. There is a professional technical team, and quality is guaranteed

2. Independent factory, more favorable price

3. Extensively trained employees are well-versed in all aspects of flow control technology

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