Methods for preventing and eliminating leaks at valve sealing surfaces

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The last edit to this post was made by kn on 2020-6-11 at 12:08. When grinding the sealing surface, it is necessary to choose appropriate grinding tools, abrasives, as well as sandpapers and other materials, and to use the correct grinding methods. After grinding, a color inspection should be carried out to ensure that there are no defects such as dents, cracks, or scratches on the sealing surface； Second, the connection between the valve stem and the closing element must meet the design requirements; if the tip of this connection does not meet these requirements, it should be adjusted. There should be a certain amount of movement allowed at this tip, and in particular, the axial gap between the valve stem shoulder and the closing element should be no less than 2 millimeters ； Third, any bending of the valve stem should be corrected; after adjustment, the valve stem, valve stem nut, closing element, and valve seat should all be aligned on a common axis ； Fourth, when selecting valves or replacing sealing surfaces, they must meet the operating conditions; after processing, the sealing surfaces should have good properties in terms of corrosion resistance, wear resistance, etc ； 5. The surfacing and heat treatment processes must meet the technical requirements specified in the regulations and standards. After the sealing surfaces are processed, they must be inspected; no defects that could affect their functionality are allowed to exist ； Sixth, processes such as surface firing, nitriding, phosphating, and plating of the sealing surface must be carried out strictly in accordance with the prescribed procedures and technical specifications. When grinding the penetration layer on the sealing surface, it should not exceed one-third of the thickness of that layer. In cases where the coating or penetration layer is severely damaged, it should be removed and the surface treated again. The sealed surface with high-frequency surface cracks can be repaired by repeated impact testing ； 7. Valves should be marked to indicate whether they are closed or open, and those that are not closed properly should be repaired promptly. For high-temperature valves, any tiny gaps that appear due to cooling contraction after closing should be sealed by closing the valve again after a certain period of time has passed ； 8. Valves used as shut-off valves must not be used as throttle valves or pressure-reducing valves; the closing element should 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 ； 9. The opening and closing of valves 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, while 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 a lever whose length is within 500 millimeters ；