Common faults and troubleshooting of ball valve internal leakage may occur during use or installation. Due to frequent switching during use, or failure to install as required, the ball valve cannot work normally.
The causes of ball valve internal leakage are mainly divided into two categories:
Causes of valve internal leakage during construction:
① Improper transportation and hoisting cause overall damage to the valve, resulting in internal leakage of the valve;
② When leaving the factory, the valve was not dried and anti-corrosion treated after water pressure, resulting in corrosion of the sealing surface and internal leakage;
③ The protection of the construction site is not in place, the blind plates are not installed at both ends of the valve, and impurities such as rain and sand enter the valve seat, resulting in leakage;
④ During installation, lubricating grease was not injected into the valve seat, causing impurities to enter the rear of the valve seat, or internal leakage caused by burns during welding;
⑤ The valve is not installed in the fully open position, resulting in damage to the ball. During welding, if the valve is not in the fully open position, the welding spatter will cause damage to the ball. When the ball with welding spatter is switched on and off, it will further cause damage to the valve seat, resulting in internal leakage;
⑥ The sealing surface is scratched by welding slag and other construction residues;
⑦ Inaccurate delivery or installation time limit causes leakage. If the assembly angle of valve stem drive sleeve or other accessories is misaligned, the valve will leak.
Causes of valve internal leakage during operation:
① The most common reason is that the operation 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 caused by improper operation or failure to maintain according to maintenance procedures;
③ During normal operation, the sealing surface is scratched by construction residues, resulting in internal leakage;
④ Improper pigging causes damage to the sealing surface and internal leakage;
⑤ If the valve is not maintained or moved for a long time, the valve seat and ball are locked, resulting in seal damage and internal leakage when opening and closing the valve;
⑥ Internal leakage is caused by valve opening and closing not in place. Leakage may be caused by any ball valve tilting 2 ° ~ 3 ° regardless of its opening and closing position;
⑦ Many large-diameter ball valves have stem stop blocks. If they are used for a long time, rust, dust, paint and other sundries will accumulate between the stem and stem stop blocks due to corrosion and other reasons. These sundries will cause the valve to fail to rotate in place and cause leakage - if the valve is buried, extending the stem will produce and drop more rust and impurities to prevent the valve ball from rotating in place, Cause valve leakage;
⑧ The general actuator is also limited. If it is rusted for a long time, the grease is hardened or the limit bolt is loose, the limit will be inaccurate and cause internal leakage;
⑨ The valve position of the electric actuator is set forward and not closed in place, resulting in internal leakage; ⑩ The lack of periodic maintenance and repair causes the sealing grease to dry and harden, and the dried sealing grease accumulates behind the elastic valve seat, hindering the movement of the valve seat and causing seal failure.
Treatment procedure for internal leakage of ball valve:
① First check the limit of the valve to see if the internal leakage of the valve can be solved by adjusting the limit.
② First inject a certain amount of grease to see if it can stop leakage. At this time, the injection speed must be slow. At the same time, observe the change of the pointer of the pressure gauge at the outlet of the grease gun to determine the internal leakage of the valve.
③ If the leakage cannot be stopped, the internal leakage may be caused by the hardening of the early injected sealing grease or the damage of the sealing surface. It is recommended to inject valve cleaning fluid to clean the sealing surface and valve seat of the valve. Generally, it shall be soaked for at least half an hour. If necessary, it can be soaked for a few hours or even a few days. The next treatment shall be carried out after all the solidified products are dissolved. In this process, it is best to open and close the movable valve several times.
④ Refill lubricating grease, open and close the valve intermittently, and discharge impurities from the rear cavity and sealing surface of the valve seat.
⑤ Check at the fully closed position. If there is still leakage, inject the reinforced sealing grease and open the valve chamber for venting, which can produce a large differential pressure and help seal. Generally, the internal leakage can be eliminated by injecting the reinforced sealing grease.
⑥ If there is still internal leakage, repair or replace the valve.