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Valves are the most commonly used control components in fluid systems; they can be used to open and close, control the flow direction, and regulate flow. Even in their simplest function of cutting off flow, valves rely on sealing mechanisms to prevent the medium from leaking out from within the chamber through the gaps between components, as well as to prevent external substances from entering. The parts that perform this sealing function are known as seals or sealing structures, simply referred to as seals. The surface on each of the two mating surfaces that comes into contact with the seal and plays a role in sealing is called a sealing surface. The valve sealing surface is the core component of a valve. The types of leaks that can occur are generally as follows: leaks at the sealing surface, leaks at the connections of the sealing rings, leaks caused by the detachment of the closing element, and leaks resulting from the presence of foreign objects between the sealing surfaces. One of the most common uses of valves in pipelines and equipment is to stop the flow of fluid; therefore, their sealing performance is the key factor determining whether internal leakage will occur. The valve sealing surface generally consists of a pair of sealing surfaces, one on the valve body and the other on the valve disc. The causes of leakage at the sealing surface are generally as follows: First, the sealing surface is not properly ground, preventing the formation of a tight seal ； Second, the tip at the connection between the valve stem and the closing element is suspended, misaligned, or worn ； Third, the valve stem is bent or not properly assembled, causing the closing element to be misaligned or out of center ； Fourth, the improper selection of the material for the sealing surface, or the use of valves that are not suitable for the given operating conditions, can lead to corrosion, erosion, and wear of the sealing surface ； Five, surfacing and heat treatment were not carried out in accordance with the procedures, resulting in defects such as wear due to low hardness, corrosion caused by the loss of alloying elements, and cracks arising from excessive internal stress ； 6. The surface-treated sealing surface peels off or loses its original properties due to excessive grinding ； 7. Improper sealing of the surface, or tiny gaps that appear due to cooling contraction after sealing, lead to pitting corrosion ； 8. Using the shut-off valve as a throttle valve or pressure reducing valve results in erosion and damage to the sealing surfaces ； 9. The valve has reached its fully closed position; continuing to apply excessive closing force, including improper use of a long lever, results in the sealing surfaces being damaged or deformed ； Ten: Excessive wear of the sealing surface leads to wire loss, that is, the sealing pair cannot fit together properly ； Methods for preventing and eliminating leaks at valve sealing surfaces: First, 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 techniques. 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 the valve stem does not meet these requirements, it should be adjusted. There should be a certain amount of play at the tip, and in particular, the axial gap between the shoulder of the valve stem and the closing element should be no less than 2 millimeters ； Third, any bending in 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 fine cracks that appear due to cooling contraction after closing should be caused to close again after a certain period of time has passed since the first closure ； 8. Valves used as shut-off valves must not be used as throttle valves or pressure relief 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 relief 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 not longer than 500 millimeters ；