What to pay attention to when repairing multi-stage centrifugal pumps

If there is a condition for the maintenance of the multi-stage pump, it is better to read the maintenance manual and the general assembly drawing of the manufacturer first to see what special places need attention.
   I. Disintegration:
   1. Before removing the thrust bearing, use a dial indicator to measure the balance plate clearance and make a record;
   2. When disassembling the multi-stage pump, the parts must be marked according to the original assembly order, so as to avoid confusion and incorrect installation during reassembly;
   3. Small pieces (such as keys) that are not easy to mark can be put together with impellers or guide vanes (middle section) of the same level.
   4. When disassembling, you can intuitively feel if there are abnormal parts, such as loose fit.
   Part Overhaul:
   1. Check whether the surface of each part is normal, and the mating surfaces must be free from scratches, rust, etc.
   2. Measure whether the tolerance of key coordination parts is qualified;
   3. Whether the gaps of the measuring wheel sealing ring, casing sealing ring, guide vane sealing ring, interstage bushing, etc. are within the tolerance range, and the excessive wear needs to be replaced;
   4. Check whether the bearing is intact;
   5. All seals and gaskets are replaced with new ones;
   Third, reload:
   1. Install the rotor first and re-run the dynamic balance test;
   2. Reinstall the parts in the reverse order of disassembling the pump. When reinstalling, pay attention to measure the gap value at each seal ring again to ensure that it is correct;
   3. Measure the total rotor string before installing the balance plate;
   4. After installing the balance disc, measure the rotor half-string.
   5. Compared with the total string quantity and half string quantity required on the general assembly drawing of the manufacturer, it should basically meet the drawing requirements. In general, the amount of half string is about half of the total string amount.
   6. Tighten the main bolts evenly, paying attention to the angle;
   7. Suction a dial indicator on the shaft, and rotate the shaft to play the balance plate. The tolerance is according to the requirements of the drawing, and generally should not exceed 0.06;
   8. When installing thrust bearings, pay attention to adjusting the gap of the balance plate. Use the adjustment ring in front of the bearing to adjust the gap of the balance plate to the requirements of the drawing.

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