Valve Sealing Requirements

The sealing performance of a valve refers to the ability of each sealing part of the valve to prevent medium leakage. It is the most important technical performance indicator of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the two sealing surfaces of the valve seat; the fit between the packing, the valve stem and the stuffing box; and the connection between the valve body and the valve cover. The first leakage is called internal leakage, which is commonly referred to as lax sealing. It will affect the valve's ability to cut off the medium. For cut-off valves, internal leakage is not allowed. The latter two leaks are called external leakage, that is, the medium leaks from inside the valve to outside the valve. Leakage will cause material loss, pollute the environment, and even cause accidents in severe cases. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.