Method of judging internal leakage of natural gas ball valve

Fixed shaft ball valve is commonly used on natural gas pipelines, and its general inspection method is: turn the valve to the fully open or fully closed position, and check whether there is leakage through the discharge of the valve body drain nozzle. If it can be drained clean, it proves that the seal is good. If there is always pressure discharge, the valve can be considered to be leaking, and the valve should be treated accordingly.