Valve sealing performance requirements

The sealing performance of a valve refers to the ability of each sealing part of the valve to prevent medium leakage, and it is the most important technical performance index of the valve. There are three sealing positions of the valve: the contact between the opening and closing member and the two sealing surfaces of the valve seat; the fitting of the packing with the valve stem and the stuffing box; and the connection between the valve body and the valve cover. The previous leak is called internal leakage, which is commonly known as improper closing, which will affect the valve's ability to intercept the medium. For shut-off valves, internal leakage is not allowed. The latter two leaks are called external leaks, that is, the medium leaks from the inside of the valve to the outside of the valve. Leakage can cause material loss, pollute the environment, and cause accidents in severe cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.