Multi-stage centrifugal pump disintegration, demolition, the impeller should be disassembled in turn all levels, and make a mark. Radial and end runout values ​​of the main parts such as rotor impeller, bushing, impeller seal ring, balance disc, journal, etc., and radial total clearance between rotor part and housing part shall be measured. The allowable deviation shall be in accordance with the corresponding technical documents Provisions. For multi-stage pumps, the rotor assembly (including the impeller, impeller block or impeller wheel balance disc, etc.) should be assembled in advance to check the concentricity and skewness of the rotor. The impeller, impeller sleeve and balance disc mounted on the calibrated pump shaft, lock with the sleeve, installed in the lathe between the top or on the V-shaped iron, measuring the rotor shaft and the coaxial parts. If the concentricity exceeds the allowable value, lathe turning can be made to meet the requirements.After the pump shaft frame is horizontal, the friction surface of the impeller mouth end surface and the balance disc should be perpendicular to the axis of the pump. If the vertical plane deflection, the operation will be serious wear and tear, or even affect the work of balance plate. Tilting exceeds the provisions of the turning correction can be used. The axial distance of the pump shaft assembly should be measured and adjusted, that is, the distance between the adjacent impeller exit, the total distance between the first stage impeller and the last stage impeller, the distance between the adjacent guide wheels and the total distance between the first stage and the last stage guide wheels. The distance between adjacent impellers should be equal and equal to the distance between adjacent guide wheels. The total distance between the first and last stage impeller outlets should be equal to the total distance between first and last stage guide wheels with washers installed between the middle stages and pressed together. In the case of a balance disc and a balance disc seat, the width of the impeller exit should be within the width of the guide wheel inlet. Adjusting the impeller exit and the guide wheel inlet "center consistent" not only ensure the normal efficiency of the pump, but also to avoid the pump does not rotate or impeller touch before and after the mill and other failure conditions. Maintenance of multi-stage pump, often need to replace the impeller seal ring, car flat diaphragm, balance plate, balance plate seat, impeller mouth face and other parts should be padded, spraying the car after the equal way to ensure or restore pump in the axial direction The size of the chain and total channeling. In order to ensure that the impeller and stator friction, impeller exit and guide wheel population alignment, but also to consider the heat pump rotor thermal elongation, multi-stage pump set a reasonable amount of axial channeling. When the total amount of each stage impeller channeling is too small, take shortening the length of the impeller seal ring approach; each stage of the total amount of impeller channeling is too large, the use of welding or replace the impeller seal ring; before and after each level of impeller channeling through the impeller rear wheel Yi The contact surface to add and subtract shims to adjust; the last impeller before and after the amount of channeling wheel balance wheel through the wheel Yi Yi or balance disc wheel Yi before adding and subtracting shims to adjust. Multi-stage centrifugal pump shaft slender, transmission power, easy to bend when working cause trouble. Deep well pump repair practice found that the shaft bending to the most prominent shaft bending. In the actual straightening work, some people wrongly judge whether there is a bending according to the value of the radial runout, which is easy to let the real bending point pass without correcting the bending point. Difficult to straighten the shaft end bending the main reason is difficult to accurately determine the pre-school bend position, the literature proposed two methods to determine the bend, that is, mapping analysis and numerical comparison. Multi-stage pump rotor assembly, no matter how much speed, should be done impeller, combined rotor static and dynamic balance.