Shutdown is mainly caused by mechanical seal defects. The performance of the problem is leakage, leakage reasons have the following several: 1, Dynamic and static ring sealing surface leakage, the main reasons are: End flatness, roughness did not meet the requirements, or the appearance of scratches; between the end surface particulate matter, the two ends can not operate equally; the device is not in place, the way is not correct. 2. Leakage of the sealing ring of compensation ring, the main reasons are: the deformation of gland, uneven pre-tightening force, incorrect device, the quality of the sealing ring does not conform to the specifications, the wrong type of sealing ring. The practical application results show that the most defective parts of the sealing elements are the end faces of the moving and stationary rings, the Slurry Pump Seals, and the crack of the end faces of the stationary rings is a common fault phenomenon. The main reasons are as follows: 1, the heat produced by the friction pair can not be carried away by the flushing fluid; the flushing fluid leaks from the gap of the sealing surface, resulting in overheating of the end surface and damage. 2, the liquid medium vaporized shrinkage, so that the two end surface by vaporized shrinkage force and separate, when the two sealing surface force-fit, destroy the smooth film to form end surface overheating. 3, the liquid medium smoothness is poor, in addition to the operation pressure overload, two sealing surface tracking rotation is not synchronized. For example, the speed of high speed pump is 20445r/min, the diameter of seal surface center is 7cm, the linear speed of pump is as high as 75m/s after running, when there is a seal surface can not follow the rotation, the seal surface is damaged by the instantaneous high temperature. 4, sealing washing liquid orifice plate or filter screen obstruction, forming a lack of water, so that the machine seal. In addition, the surface of the seal groove, the end of the joint when the gap caused by sealing elements defects, the main reasons are: 1, the liquid medium is not clean, there are tiny hard particles, with a very high speed sliding seal surface, scratch the surface of the end surface. 2. Poor coaxiality of the driving parts of the pump, the end face is shaken and rubbed once every turn after the pump is turned on, and the running track of the moving ring is different, resulting in end face vaporization and over-heat wear. 3, the frequent occurrence of the hydraulic characteristics of the liquid medium caused the pump vibration, the formation of seal surface dislocation and fault. The corrosion of liquid medium to sealing elements, stress concentration, soft and hard data matching, erosion, auxiliary sealing 0-ring, v-ring, concave ring and liquid medium are incompatible, deformation, etc. , therefore, the damage mode should be comprehensively analyzed to find out the basic reasons to ensure the long-term operation of mechanical seals.