How tight should the locking nut of a multi-stage pump be tightened
Thread Content
The rotor of the boiler feedwater pump has been disassembled several times recently, and there are always areas where scraping occurs when installing the shaft bearings at both ends. So it was taken apart again to inspect various parts of the rotor. After installing the impeller shaft sleeve, balance disk, and other components, it was placed on a V-block, and a dial indicator was used to check for vibrations; in a relaxed state, the vibration level was within 0.05. However, as soon as the locking nut was tightened, the vibration level rose to 0.3. This indicates that the shaft sleeve and impeller are not parallel; the back sides of the shaft sleeve and impeller were ground, while the inlet end could not be processed due to the weld points of the mouth ring. Even after grinding it to a near-finish, don’t apply too much force; the greater the force applied, the different the maximum angle of vibration will be. Is there a standard torque for this thing?
The impeller of grade 567 is slightly damaged, but it cannot be ground; the welds around it are higher than it, so it can only be polished with sandpaper
For boiler multi-stage pumps, remember that the drawings used to require a gap between each impeller. But later on, that product was no longer indicated on the drawings. What to do? Just merge the two caps together; the gap at the front can be left at around 0 to 0.20 mm, with the value chosen based on the water temperature. This is my suggestion; please take it into consideration.
The clearance between the inner hole of this impeller and the shaft might be large
Should a total gap of 0.2 be left for all the bushings, impellers, and balance discs? Won’t it vibrate without a tension impeller and balance disk? Then grind the shaft finer?
The clearance between the impeller shaft sleeve and the shaft is too large; it must not exceed 5 microns
Is it the end face of the balance disc? If the measurement conditions aren’t met, then no measurement is taken; there’s no axial positioning either. Thinking about it now, it’s completely possible to use two dial indicators for the measurement.
This post was last edited by 3983596_FPPZ on 2019-12-24 at 16:15. This tightening force is not calculated according to standards; otherwise it would be too high. It is recommended to use processing equipment to align the mandrel and then level the end face
Is the balance disc in close contact with the striking end face, or is there any deviation?