What should be paid attention to during maintenance of multistage centrifugal pump

 

If conditions permit, it is better to read the manufacturer's maintenance instructions and general assembly drawings first to see what special points need attention.
1、 During disassembly:
1. Before removing the thrust bearing, measure the clearance of the balance disc with a dial indicator and make records;
2. When disassembling the multistage pump, all parts must be marked according to the original assembly sequence to avoid confusion and wrong installation during reassembly;
3. Small parts (such as keys) that are not convenient for marking can be put together with impellers or guide vanes (middle section) at the same level.
4. During disassembly, you can visually feel whether there are abnormal parts, such as loose fit.
2、 Parts maintenance:
1. Visually check whether the surface of each part is normal, and all mating surfaces must be free of bumps, scratches, rust, etc;
2. Use measuring tools to measure whether the tolerance of key mating parts is qualified;
3. Measure whether the clearance of impeller seal ring, housing seal ring, guide vane seal ring, interstage shaft sleeve, etc. is within the tolerance range, and replace them if they are excessively worn;
4. Check whether the bearing is in good condition;
5. All sealing rings and gaskets shall be replaced if they are superior;
3、 Reinstallation:
1. First install the rotor and conduct dynamic balance test again;
2. Reassemble all parts in the reverse order of pump disassembly. During reassembly, pay attention to the clearance value of each seal ring again to ensure that it is correct;
3. Before installing the balance disc, measure the total rotor runout;
4. After installing the balance disc, measure the rotor half run.
5. Compared with the total string quantity and half string quantity required on the general assembly drawing of the manufacturer, they should basically meet the drawing requirements. Generally, the half string quantity is about half of the total string quantity.
6. Tighten all the main bolts evenly and diagonally;
7. Draw a dial indicator on the shaft, and rotate the shaft to mark the balance disc. The tolerance shall be in accordance with the drawing requirements and generally shall not exceed 0.06;
8. When installing the thrust bearing, pay attention to adjusting the clearance of the balance disc, and use the adjusting ring in front of the bearing to adjust the clearance of the balance disc to the drawing requirements.

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