Answer: After long-term operation, the end faces of the moving ring and the stationary ring will wear due to friction, the spring and the sleeve will also rust or damage, and the sealing ring will lose its elasticity due to aging and deformation. All these reasons will cause mechanical seal leakage. Therefore, after a long period of operation, the mechanical seal components must be replaced or overhauled to achieve the purpose of reuse.
(1) Grinding of the end faces of the moving ring and the stationary ring. After the moving ring is removed, it is ground, first rough ground, then fine ground, and polished if conditions permit.
When rough grinding, use abrasives with a grit of 80~160 to first remove the processing marks. Then, fine grinding can be performed with abrasives above 160 to achieve a smooth finish that meets the design requirements. After fine grinding of carbide or ceramic moving rings, it needs to be polished with a polishing machine. The strength of the polishing machine can be selected from M28~M5 boron carbide. After polishing, it reaches a mirror surface. Ceramic rings can be fine ground with M5 agate powder and then polished with chromium oxide.
Graphite-filled polytetrafluoroethylene stationary rings can be ground with kerosene, gasoline or water because the material is soft, without the need for abrasives. They can also be ground by themselves during the running-in process, so the finish requirement is not too high.
The grinding method can be ground on a grinder if there is one, or by hand grinding in an 8-shaped pattern on flat glass if there is no grinder.
(2) Shaft sleeve inspection. After the shaft sleeve is disassembled for inspection, check the rust and wear. If the rust or wear is relatively minor, it can be polished with fine sandpaper and reused. If the rust or wear is severe, it can be processed and electroplated or replaced with a new shaft sleeve.
(3) Sealing ring. After a period of use, the sealing ring usually loses its elasticity or ages, and generally needs to be replaced with a new ring.
(4) Spring. If the spring is not severely corroded and can maintain its original elasticity, it does not need to be replaced. If the rust is severe or the elasticity is greatly reduced, a new spring needs to be replaced.
For mechanical seals with assembly boxes, the boxes should be cleaned and the grooves should be checked for wear or deformation so that corrections, repairs, regrooving or replacements can be performed.
After the mechanical seal components are repaired, they should be reassembled and pressure tested before being put into normal operation.
