Thread Content
The sealing surface of a valve is its core component. Leaks can occur in the following ways: leakage at the sealing surface, leakage at the connection points of the sealing rings, leakage caused by the detachment of the closing element, and leakage resulting from the presence of foreign objects between the sealing surfaces. 1. Leakage at the sealing surface can be caused by: 1) The pivot point at the connection between the valve stem and the closing element being loose, misaligned, or worn out. 2) The valve stem is bent or misassembled, causing the closing element to be skewed or out of alignment. 3) Using the cut-off valve as a throttle valve or pressure reducing valve causes the sealing surface to be eroded and damaged. 4) The valve has reached the fully closed position; continuing to apply excessive closing force, including improper use of a long lever, causes the sealing surfaces to be damaged or deformed. 5) Excessive wear of the sealing surface leads to wire loss, that is, the sealing pair cannot fit together properly. 2. Prevention and elimination methods: 1) The connection between the valve stem and the closing element must meet the design requirements; if the area at the tip does not meet these requirements, it should be adjusted. There should be a certain amount of play at the tip, especially the axial gap between the valve stem shoulder and the closing element should be no less than 2 millimeters. 2) The bent valve stem should be straightened; after adjustment, the valve stem, valve stem nut, closing element, and valve seat should all be on the same common axis. 3) Valves used as shut-off valves shall not be used as throttle valves or pressure-reducing valves; the closing element must be in either the fully open or fully closed position. If it is necessary to regulate the flow rate and pressure of the medium, separate throttle valves and pressure-reducing valves should be installed. 4) The operation of the valve before it is opened or closed shall comply with the section on \"Valve Operation\". The closing force of the valve should be appropriate; if the diameter of the handwheel is less than 320 millimeters, only one person is allowed to operate it. For handwheels with a diameter of 320 millimeters or more, two people may operate it, or one person can operate it with the help of an F wrench with a length of up to 500 millimeters. 5) Once the seal on the cover loses its effectiveness, adjustments should be made; for seal surfaces that cannot be adjusted, they must be replaced.