Cause Analysis Of Seal Damage

1. Fatigue damage. In the long-term use of the seal, the valve will cause fatigue on the surface of the seal under the effect of alternating load, showing cracks and peeling layers. Through long-term use of rubber and plastic, aging phenomenon occurs, resulting in poor performance.

2. Mechanical damage, the skeleton oil seal will be scratched, bumped, crushed and other damage during the opening and closing process. Between the two seals, the atoms penetrate each other under the effect of high temperature and high pressure, and the appearance of adhesion occurs. When the two seals are moved relative to each other, the adhesion is easily pulled and torn. The higher the surface roughness of the seal, the more likely this phenomenon occurs. During the locking process of the valve and the valve disc during the reseating process, the sealing surface will be bruised and squeezed, causing some wear or indentation on the sealing surface.

3. Electrochemical erosion, the contact between the sealing surfaces of the oil seal, the contact between the sealing surface and the lock body and the valve body, and the concentration difference of the medium and the difference in oxygen concentration, etc., will cause a potential difference and electrochemical erosion, resulting in the sealing surface on the anode side. eroded.

4.The chemical erosion of the medium, the medium near the seal will directly have a chemical effect with the seal in the absence of current, and the seal will be eroded.

5. Improper installation and poor repair lead to abnormal function of the seals, and the valves work with diseases, which prematurely damage the seals.

6. Damage caused by improper selection and manipulation. The main table is that the valve is not selected according to the working conditions, and the blocking valve is used as a throttle valve, which leads to excessive locking ratio pressure and fast locking or loose locking, which causes the seals to be eroded and worn.

7. The processing quality of seals is not good, mainly due to the defects such as cracks, pores and lumps on the seals, which are caused by improper selection of surfacing and heat treatment scales and manipulation during surfacing and heat treatment. Too high or too low is caused by different material selection or improper heat treatment. The hardness of the sealing ring is uneven and it is not resistant to corrosion. The main reason is that the underlying metal is blown to the top during the surfacing process, which weakens the sealing ring alloy. caused by the ingredients. Of course, there are also issues of description here.

8. Erosion of the medium, which is the result of wear, flushing and cavitation of the seal when the medium flows. At a certain speed of the medium, the floating fine particles in the medium collide with the sealing ring of the combined gasket, causing some damage. The high-speed flowing medium directly washes the seal, causing some damage. When the medium is mixed and some vaporized, bubble impact occurs. The outer surface of the sealing surface is damaged. The erosion of the medium and the substitution effect of chemical erosion will severely erode the seal.

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

1. There are two reasons for the damage of the sealing surface: man-made damage and natural damage.

1) Man-made damage is caused by factors such as poor description, poor production, improper selection of materials, improper installation, poor use and improper repair.

2) Natural damage is the wear and tear of the valve under normal working conditions, and the inevitable erosion and erosion of the sealing surface by the medium.

2. Since the seal plays the role of blocking and connecting, distributing, separating and mixing media on the valve channel, the sealing surface is often eroded, eroded and worn by the medium, and is easily damaged.