The equalizing pipe of multi-stage centrifugal pump is a balancing method, not an equalizing structure. Whether it is an equalizing disc or an equalizing drum (or the combination of the two) is based on these methods to equalize the thrust. So what is the function of the equalizing pipe of multi-stage centrifugal pump? From the outlet sealing ring of the multi-stage centrifugal pump, an external pipe is led to the inlet end of the multi-stage centrifugal pump, which is called the equalizing pipe. Its key function is to balance the axial thrust of the centrifugal water pump, reduce the axial shaking of the motor rotor, and prevent the friction between the impeller and the casing. When the multi-stage centrifugal pump is running, high-pressure water is discharged from the impeller outlet, and one unit flows behind the impeller, so that the working pressure behind the impeller is basically the same as that at the outlet, while the outside of the coaxial cable of the blade is the suction end, and the working pressure is very low. In that way, there is a large pressure difference on both sides of the impeller, which will produce an axial thrust that is biased towards the pump inlet and parallel to the shaft, so that all motor rotors will press towards the suction side. In serious cases, it will cause friction or collision between the impeller and the pump body, endangering the safe operation of the pump, so it is necessary to balance it. There are many methods to balance the axial thrust of multi-stage centrifugal pump, such as selecting double suction impeller or symmetrical sequencing impeller (multi-stage centrifugal pump), selecting equalizing hole, equalizing disc, equalizing drum, etc. The balance pipe is only a method to balance the axial thrust. It uses the balance pipe to lead the burden water behind the impeller to the inlet side, so that the working pressure on both sides of the impeller is in phase. This kind of method is simple in structure, but it cannot completely balance the axial thrust. The residual axial thrust must be borne by professionally installed thrust rolling bearings.