• Causes of Valve Leakage

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Causes of Valve Leakage

  • 01 04, 2021
Causes of internal leakage of valves during construction

1. Improper transportation and hoisting cause the overall damage of the valve, resulting in internal leakage of the valve.

2. Before the valve leaves the factory, drying and preservative treatment are not performed after the water pressure test is finished, leading to corrosion of the sealing surface and internal leakage.

3. Lack of valve protection on the construction site will also contribute to leakage. Blind disks are not installed at both ends of the valve, and impurities such as rainwater and sand enter the valve seat, causing leakage.

4. During installation, the valve seat is not greased, which causes impurities to enter the back of the valve seat, causing internal leakage of valves.

5. The valve is not installed when it is fully open, causing damage to the ball. During welding, if the valve is not in the full open position, welding spatter will be a contributor to the damage of the ball. When the ball with welding spatter is opened and closed, it will further cause damage to the valve seat, resulting in internal leakage.

6. Welding slag and other debris cause scratches on the sealing surface of the valve.

7. Leakage is caused by inaccurate limiting displacement at the time of delivery or installation. If the assembly angle of the stem’s drive bushing or other accessories is misplaced, the valve will leak.

Causes of internal leakage of valves during operation

1. The most common reason is that the operations manager does not maintain the valve in consideration of the relatively expensive maintenance cost, or does not carry out preventive maintenance for the valve due to the lack of scientific valve management and maintenance methods, resulting in equipment failure in advance.

2. Internal leakage can be caused by improper operation or failure to carry out maintenance according to maintenance procedures.

3. During normal operation, construction waste scratches the sealing surface, causing internal leakage.

4. Improper pigging causes damage to the sealing surface and internal leakage.

5. If the valve is not maintained or operated for a long time, the valve seat and the ball will lock, and the sealing will be affected when the valve is opened and closed, resulting in internal leakage.

6. Improper opening and closing of valves cause internal leakage.

7. Many large-diameter ball valves have valve stem stoppers. If they are used for a long time, rust, dust, paint and other debris will accumulate between the valve stem and the stem stoppers due to rustiness and other reasons. The debris will cause the valve to fail to rotate in place and give rise to leakage. If the valve is buried, the extended stem will produce and drop more rust and impurities, preventing the valve ball from rotating in place and contributing to valve leakage.

8. General actuators have limiting displacement. If the valve is corroded for a long time, grease hardening or loose stop bolts will make the limit displacement inaccurate and cause internal leakage.

9. Lack of periodic maintenance causes the sealing grease to dry and harden, and the dried sealing grease accumulates behind the elastic seat, hindering the movement of the seat and causing seal failure.
 
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