Causes of valve leakage during construction or operation

Causes of valve leakage during construction or operation

Causes of internal leakage in valves during operation:

① The most common cause is that operators fail to maintain valves due to high maintenance costs, or lack scientific valve management and maintenance methods and fail to perform preventative maintenance, resulting in premature equipment failure;

② Improper operation or failure to follow maintenance procedures can cause internal leakage;

③ During normal operation, construction debris can scratch the sealing surface, causing internal leakage;

④ Improper cleaning can damage the sealing surface, causing internal leakage;

⑤ Long-term neglect of maintenance or inactivity of valves can cause the valve seat and ball to seize, resulting in seal damage and internal leakage when the valve is opened or closed;

⑥ Incorrect valve opening or closing can cause internal leakage. Any ball valve, regardless of whether it is open or closed, may leak if tilted by 2° to 3° [2];

⑦ Many large-diameter ball valves have a valve stem stop block. If used for a long time, rust, dust, paint and other debris will accumulate between the valve stem and the valve stem stop block due to corrosion and other reasons. These debris will prevent the valve from rotating to the correct position and cause leakage. If the valve is buried, an extended valve stem will generate and collect more rust and impurities, hindering the valve ball from rotating into place and causing valve leakage.

⑧ General actuators also have limit switches. Long-term rust, hardened grease, or loose limit bolts will cause inaccurate limit switching, resulting in internal leakage.

⑨ An electric actuator with the valve position set too far forward, not fully closed, will cause internal leakage.

⑩ Lack of periodic maintenance and upkeep causes the sealing grease to dry and harden. The dried grease accumulates behind the resilient valve seat, hindering its movement and causing seal failure.

Causes of internal leakage in valves during construction:

① Improper transportation and hoisting cause overall damage to the valve, resulting in internal leakage;

② Failure to dry and treat the valve after pressure testing at the factory leads to rust on the sealing surface and internal leakage;

③ Inadequate protection at the construction site, such as the absence of blind flanges at both ends of the valve, allows rainwater, sand, and other impurities to enter the valve seat, causing leakage;

④ Failure to inject grease into the valve seat during installation allows impurities to enter the rear of the valve seat, or welding burns can cause internal leakage;

⑤ The valve is not installed in the fully open position, causing damage to the valve ball. During welding, if the valve is not in the fully open position, welding spatter will damage the valve ball. When the ball with welding spatter is opened and closed, it will further damage the valve seat, leading to internal leakage;

⑥ Weld slag and other construction residues cause scratches on the sealing surface;

⑦ Inaccurate limit switches at the factory or during installation cause leakage. If the valve stem drive sleeve or other accessories are misaligned during assembly, the valve will leak.