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After long-term operation, the end faces of the rotating ring and the stationary ring in a mechanical seal become worn due to friction; the springs and shaft sleeves may also rust or get damaged. The sealing rings lose their elasticity as a result of aging and deformation. All these factors can cause leakage in the mechanical seal. Therefore, after long-term operation, the mechanical seal components need to be replaced or repaired in order to enable them to be used again. 1. Grinding of the end faces of the rotating ring and the stationary ring: After the rotating ring is removed, it is subjected to grinding processes – first rough grinding, then fine grinding; polishing can be carried out if conditions permit. During rough grinding, use abrasives with a particle size of 80–160# to first remove the traces of machining. Then, fine grinding can be carried out using abrasives of grade 160# or higher to achieve the desired level of smoothness. The cemented carbide or ceramic moving ring needs to be polished using a polishing machine after precision grinding. For the polishing machine, boron carbide grades M28 to M5 can be used. It reaches a mirror finish after polishing. The ceramic ring can be finely ground using M5 agate powder and then polished with chromium oxide. The static ring made of graphite-filled polytetrafluoroethylene can be finely ground using kerosene, gasoline, or clean water, as the material is soft; no grinding agents are required. During the running-in period, it can also be developed independently; therefore, the requirement for surface finish is not very high. For the grinding method, if a grinder is available, grinding can be done using it; if no grinder is available, a manual 8-shaped grinding technique can be employed on flat glass. 2. Bushing inspection: After removing the bushing for maintenance, check for signs of rust and wear. If the rust or wear is minor, it can be polished with fine sandpaper before being reused; if the rust or wear is severe, machining followed by electroplating or replacing the bushing with a new one may be necessary. 3. Sealing ring: After being in use for a period of time, the sealing ring loses its elasticity or ages in most cases, and it is generally necessary to replace it with a new one. 4. Spring: If the spring is not severely rusted and can still maintain its original elasticity, it does not need to be replaced. If the rusting is severe or the elasticity has decreased significantly, a new spring needs to be replaced. For mechanical seals that come with an assembly box, the box must be cleaned thoroughly, and it is necessary to check whether the grooves are worn or deformed, so that corrections can be made, the grooves can be re-cut, or the parts can be replaced. After the mechanical seal components are repaired, they are reassembled. A pressure test is conducted again after assembly, followed by resuming normal operation.