Page 41 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

26 Major Process Equipment Maintenance and Repair

If failed bearings are suspected in pump or motor:
Check radial clearance and end float in motor.
Run motor and check for abnormal noise, vibration.
If motor is bad, remove and repair.

Diagnosing Pump and Seal Problems In the Shop

While the pump is being repaired it is advisable to carefully examine
every component. A recommended procedure is to match mark all parts
prior to disassembly and to make the following checks while dismantling
the pump:

1. Visually check impeller and nut for wear, erosion, corrosion and
other deterioration.
2. Remove seal flange nuts and check seal tension.
3. Record impeller position in relation to pump frame.
4. Remove impeller nut and impeller.
5. Jnspect wear rings inboard, if any.
6. Check and record throttle bushing clearance.
7. Check body gasket faces.
8. Remove stuffing box body from pump frame.
9. Check stuffing box gasket face, bore, and pilots.
10. Remove and inspect all shaft keys.
11. Remove sleeve, seal, sleeve gasket and sleeve flange. If neces-
sary, determine the cause of seal failure and inspect condition of
parts.
12. Check pump bearings for roughness. Record shaft end float,
check shaft for wear, erosion, corrosion and straightness.
13. Excessive shaft axial end play:

Excessive shaft movement can result in pitting, fretting, or wear at
points of contact in shaft packing and mechanical seal areas. It can
cause over or under-loading on springs resulting in high wear rates
and leakage. It can also cause excessive strain and wear on pump
bearings. Defective bearings in turn can cause excessive shaft end
Play.
To check for this condition a dial indicator should be installed so
that its stem bears against the shoulder on the shaft (Figure 1-6).