Abstract: Using high pressure fluid at the outlet of pump, the pump inlet valve seal groove is backwashed and cleaned up. With the help of the fine seam flushing of high speed fluid under a differential pressure of 1.5MPa, the ball type iron slag in the 55mm can be cleaned up in theory, so that most of the dirt deposited can be cleaned up and the internal leakage problem of the inlet valve can be solved. In practical application, the success rate of backwashing of the pump inlet valve is found to be nearly 70%. Therefore, the emergency shutdown of process units caused is reduced by about 24%

Key words: Pump inlet valve, Internal leakage, Backwashing