The ball valve may have an internal leakage during use or installation. Due to the frequent switch in use, or failure to install as required, the ball valve may not work properly. In the following part, Xhvalve will explain the reasons and solutions for the leakage of the ball valve.
1. Causes of ball valve internal leakage
1） During construction:
① Improper transportation and hoisting damage integral valve, leading to internal leakage of the valve;
② When leaving the factory, staff do not dry the valve and make anti-corrosion treatment after finishing the water pressure, so the sealing surface corrodes with rust to form internal leakage;
③ The safeguard is implemented not perfectly in construction site, and there is no blind plate installed at both of the valve, rainwater, sand and other impurities into the valve seat, resulting in leakage;
④ During installation, no grease is injected into the valve seat, contributing impurities to enter the rear of the valve seat, or burns causing internal leakage during welding.
⑤ The valve is installed or welded not in a full open position, which all will damage the ball. When the ball with the welding spatter is in switch, the valve seat will be damaged further, forming the internal leakage.
⑥ If the limit is not accurate during the installation, and the stem's drive bushing is misaligned with other accessories, the valve will leak.
2） During operation:
① The most common reason is that the manager does not maintain the valve due to the relatively expensive maintenance cost, or lack scientific valve management and maintenance methods, the equipment tends to be fail in advance;
② In normal operation, the construction residues scratch the sealing surface, causing internal leakage;
③ Improper cleaning of pipes damages sealing surface, leading to internal leakage;
④ Long-term inactivity of the valve, the valve seat and the ball will lock, which damages the sealing surface when opening and closing the valve and forms an internal leakage;
⑤ The valve switch is not in place to cause internal leakage. Any ball valve whether on or off, generally tilting 2 °~ 3 °may results in leakage.
2. The judgment method of ball valve internal leakage
Commonly used on natural gas pipelines are fixed-shaft ball valves. The general inspection method is: turn the valve to full open or full closed position, and check whether there is leakage through the discharge of the valve body drain nozzle. If it can be drained, it proves that the seal is good. If there is always pressure discharge, the valve can be considered to have leaked, and the valve should be treated accordingly. However, that should emphasize specially that the GRoVEB-5, B-7A ball valves, PBV ball valves, and ROBERTCORT ball valves can only be inspected in the full position because these ball valves open a passage in the valve body. When fully open, which used to balance the pressure in the pipeline and valve cavity. But this will not happen when it is fully closed.
3. The Handling procedure of ball valve internal leakage
1） Check the valve limit to see if the valve leakage can be solved by adjusting the limit.
2） Inject a certain amount of grease to observe whether the leakage can be stopped, and the injection speed must be slow. At the same time, observe the change of the pointer of the grease gun outlet pressure gauge to determine the condition of ball valve internal leakage.
3） If the leak cannot be stopped, it is possible that the sealing grease was injected in early stage hardened or the seal surface damaged to cause internal leakage. It is recommended to inject the valve cleaning fluid at this time to clean the sealing surface of the valve and the valve seat. Generally, it is immersed for at least half an hour. If necessary, it can be immersed for several hours or even several days, and then do next step after the solidified materials are all dissolved. It is best to switch the valve on and off several times during this process.
4） Re-inject the grease, opening and closing the valve intermittently, and discharge the impurities out of the rear cavity and sealing surface of the valve seat.
5） Check in the full position. If there is still leakage, the reinforced sealing grease should be injected, and the valve cavity should be opened for venting, which can produce a large pressure difference and helps to seal. In general, leaks can be eliminated by injecting reinforced sealing grease.
6） If there is still an internal leak, repair or replace the valve.
1. Causes of ball valve internal leakage
1） During construction:
① Improper transportation and hoisting damage integral valve, leading to internal leakage of the valve;
② When leaving the factory, staff do not dry the valve and make anti-corrosion treatment after finishing the water pressure, so the sealing surface corrodes with rust to form internal leakage;
③ The safeguard is implemented not perfectly in construction site, and there is no blind plate installed at both of the valve, rainwater, sand and other impurities into the valve seat, resulting in leakage;
④ During installation, no grease is injected into the valve seat, contributing impurities to enter the rear of the valve seat, or burns causing internal leakage during welding.
⑤ The valve is installed or welded not in a full open position, which all will damage the ball. When the ball with the welding spatter is in switch, the valve seat will be damaged further, forming the internal leakage.
⑥ If the limit is not accurate during the installation, and the stem's drive bushing is misaligned with other accessories, the valve will leak.
2） During operation:
① The most common reason is that the manager does not maintain the valve due to the relatively expensive maintenance cost, or lack scientific valve management and maintenance methods, the equipment tends to be fail in advance;
② In normal operation, the construction residues scratch the sealing surface, causing internal leakage;
③ Improper cleaning of pipes damages sealing surface, leading to internal leakage;
④ Long-term inactivity of the valve, the valve seat and the ball will lock, which damages the sealing surface when opening and closing the valve and forms an internal leakage;
⑤ The valve switch is not in place to cause internal leakage. Any ball valve whether on or off, generally tilting 2 °~ 3 °may results in leakage.
2. The judgment method of ball valve internal leakage
Commonly used on natural gas pipelines are fixed-shaft ball valves. The general inspection method is: turn the valve to full open or full closed position, and check whether there is leakage through the discharge of the valve body drain nozzle. If it can be drained, it proves that the seal is good. If there is always pressure discharge, the valve can be considered to have leaked, and the valve should be treated accordingly. However, that should emphasize specially that the GRoVEB-5, B-7A ball valves, PBV ball valves, and ROBERTCORT ball valves can only be inspected in the full position because these ball valves open a passage in the valve body. When fully open, which used to balance the pressure in the pipeline and valve cavity. But this will not happen when it is fully closed.
3. The Handling procedure of ball valve internal leakage
1） Check the valve limit to see if the valve leakage can be solved by adjusting the limit.
2） Inject a certain amount of grease to observe whether the leakage can be stopped, and the injection speed must be slow. At the same time, observe the change of the pointer of the grease gun outlet pressure gauge to determine the condition of ball valve internal leakage.
3） If the leak cannot be stopped, it is possible that the sealing grease was injected in early stage hardened or the seal surface damaged to cause internal leakage. It is recommended to inject the valve cleaning fluid at this time to clean the sealing surface of the valve and the valve seat. Generally, it is immersed for at least half an hour. If necessary, it can be immersed for several hours or even several days, and then do next step after the solidified materials are all dissolved. It is best to switch the valve on and off several times during this process.
4） Re-inject the grease, opening and closing the valve intermittently, and discharge the impurities out of the rear cavity and sealing surface of the valve seat.
5） Check in the full position. If there is still leakage, the reinforced sealing grease should be injected, and the valve cavity should be opened for venting, which can produce a large pressure difference and helps to seal. In general, leaks can be eliminated by injecting reinforced sealing grease.
6） If there is still an internal leak, repair or replace the valve.
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