Fully welded ball valves are widely applied in natural gas pipelines. It is very important to judge the seat leakage and solve the problem timely.

How to find?

Those ball valves that are common used in natural gas pipelines are trunnion mounted configuration. The general inspection method is to turn the valve to the fully open or fully closed position, and check whether there is a leak through the discharge of the valve body drain nozzle. If it can be drained, it proves a good seal. If the pressure is always discharged, the valve can be considered to be leaking, and the valve should be treated accordingly.

Natural gas ball valve internal leakage treatment procedures

①  Check the limit device of the valve to see if the seat leakage of the valve can be solved by adjusting the limit device.

②  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 leakage of the valve.

③  If the leakage cannot be stopped, the sealing grease injected earlier may be hardened or the sealing surface may be damaged, causing internal leakage. It is recommended to inject valve cleaning fluid at this time to clean the sealing surface of the valve and the valve seat. Generally soak for at least half an hour, if necessary, soak for several hours or even several days, and then proceed to the next step after the solidified material is completely dissolved. It is best to open and close the movable valve several times during this process.

④  Refill the grease, open and close the valve intermittently, and expel the impurities from the back cavity and sealing surface of the valve seat.

⑤  Check at the fully closed position. If there is still leakage, inject reinforced sealing grease and open the valve cavity to vent at the same time. This can generate a large pressure difference and help seal. Generally, by injecting reinforced sealing grease, the leak can be eliminated.

⑥   If there is still internal leakage, repair or replace the valve.

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