Abstract: In operation of the horizontal type 9stage centrifugal oil delivery pump of a thermal power plant in Zhengzhou, the balance disc was worn seriously, and the oil leakage fault was occurred frequently in machine sealing. The above problems were analyzed; and according to this analysis, it was determined that the main reason of wear of the balance disc is that the axial thrust can not be counteracted by the balance disc. Relevant reformation measures were adopted, and the fault rate of the oil feeding multistage pump was decreased greatly.

Key words: multistage centrifugal pump, axial thrust, balance disc