There are two kinds of reasons for the damage of multistage pump seals: man-made damage and natural damage. The seals of multistage pumps will be damaged by scratches, bumps, and squeezes when they are opened or closed too much. Mechanical damage between two sealing surfaces. Under the action of high temperature and pressure, atoms permeate each other and stick together. When the two sealing surfaces move each other, the adhesion can be easily pulled and torn. The higher the roughness of the sealing surface of multistage pump, the more easily this phenomenon occurs.

Wear, wash and cavitate the sealing surface of multistage pump when the medium is moving. The floating fine particles in the medium collide with and offend the sealing surface, causing local damage. The high-speed moving medium directly washes the sealing surface, causing local damage. When the medium is mixed and partially vaporized, gas bubbles are produced to blast and impact the sealing surface, causing local damage. The erosion of the medium combined with the chemical erosion will strongly erode the sealing surface.

The contact between sealing surfaces, the contact between sealing surfaces and sealing body and valve body, the concentration difference of medium, oxygen concentration difference and other reasons will lead to potential difference and electrochemical erosion, which will lead to the erosion of the sealing surface on the anode side. However, when the medium near the sealing surface does not generate current, the medium directly reacts with the sealing surface, forming chemical erosion, which erodes the sealing surface.

The processing quality of the sealing surface is poor, which mainly indicates that there are cracks, air holes, slag inclusions and other defects on the sealing surface. The hardness of the sealing surface is too high or too low due to improper selection of surfacing and heat treatment specifications and poor control during surfacing and heat treatment. The uneven hardness and corrosion resistance of the sealing surface caused by incorrect selection of materials or improper heat treatment are mainly caused by diluting the alloy composition of the sealing surface by blowing the bottom metal onto it during surfacing.