Many Reasons For Valve Internal Leakage
1) Reasons for internal leakage of Globe Valve during construction:
① Improper transportation and hoisting cause overall damage to the valve and then cause internal leakage of the valve;
② When leaving the factory, the valve is not dried and anti-corrosion treated after water pressure is applied, resulting in rust on the sealing surface and internal leakage;
③ The construction site is not properly maintained, and blind plates are not installed at both ends of the valve, causing rainwater, sand and other impurities to enter the valve seat, causing leakage;
④ During installation, no grease is injected into the valve seat, causing impurities to enter the back of the valve seat, or burning during welding causes internal leakage;
⑤ The valve is not installed in the full open position, causing ball damage. During welding, if the valve is not in the full open position, welding spatter will cause ball damage. When the ball with welding spatter is switched, it will further cause valve seat damage, resulting in internal leakage;
⑥ Welding slag and other construction residues cause scratches on the sealing surface;
⑦ Leakage caused by inaccurate limit position during factory or installation. If the valve stem drive sleeve or other accessories are misaligned with the assembly angle, the valve will leak.
2) Reasons for valve internal leakage during operation:
① The most common reason is that the operator does not maintain the valve due to the relatively expensive maintenance costs, or lacks scientific valve management and maintenance methods to prevent the valve from being maintained, resulting in early equipment failure;
② Improper operation or failure to perform maintenance in accordance with the maintenance procedures causes internal leakage;
③ During normal operation, construction residues scratch the sealing surface, causing internal leakage;
④ Improper pipe cleaning causes sealing surface damage and internal leakage;
⑤ Long-term failure to maintain or activate the valve causes the valve seat and the ball to lock, causing sealing damage and internal leakage when the valve is opened and closed;
⑥ Internal leakage caused by incomplete valve opening and closing. Any ball valve, regardless of the open or closed position, generally causes leakage if it is tilted by 2° to 3°;
⑦ Many large-mouth Most diameter ball valves have stem stops. If they are used for a long time, rust, dust, paint and other debris will accumulate between the stem and the stem stop due to corrosion and other reasons. These debris will cause the valve to be unable to rotate into place and cause leakage. If the valve is buried, the extended stem will produce and drop more rust and impurities to prevent the valve ball from rotating into place, causing the valve to leak.
⑧General actuators also have limits. If rust forms over a long period of time, the grease hardens or the limit bolts loosen, the limit will be inaccurate, causing internal leakage;
⑨The valve position of the electric actuator is set forward, and it is not closed in place, causing internal leakage;
⑩Lack of periodic protection and maintenance causes the sealing grease to dry and harden. The dried sealing grease accumulates behind the elastic valve seat, preventing the valve seat from moving, causing sealing failure.
