(1) Valve leakage is due to the improper length of the valve stem. The length of the valve stem of the air opening valve is too long, which makes the upward or downward distance of the valve stem too short, resulting in a gap between the valve core and the valve seat and no complete contact, resulting in valve internal leakage.

(2) If the packing leaks, installing the packing into the stuffing box will exert axial pressure on the regulating valve. Due to the plastic deformation of the packing, radial pressure will be generated, which is in close contact with the valve stem, but the contact is uneven.

During the operation of the regulating valve, the valve stem and packing will move axially. Under the environment of high temperature and high pressure, packing leakage is easy to occur under the influence of high permeability fluid medium.

(3) The valve core and valve seat are deformed, leaked, eroded and impacted, resulting in deformation. With the passage of time, there will be a mismatch between the valve core and valve seat. There is a gap between them, resulting in leakage due to lax closing.