Centrifugal Compressor and Lube System Troubleshooting Checklist

Symptoms Possible Causes
Excessive Vibration 1-4-5-6-8-9-10-11-12-13-14-15-22-23-24-25
Compressor Surges 6-7-16-17
Loss of Discharge Pressure 18-19-20
Low Lube-Oil Pressure 27-29-30-31-32-36-37-38-39-40-41
Excessive Bearing Oil Drain Temperature 2-3-21-28-33-34-35-42-43-44
Units Do Not Stay in Alignment 25-26
Water in Lube-Oil 45-46

Possible Causes Possible Solutions

1. Excessive Bearing Clearance Replace bearings
2. Wiped Bearings Replace bearings Determine and correct cause
3. Rough Rotor Shaft Journal Surface Stone or restore journals Replace shaft
4. Bent Rotor (caused by uneven heating or cooling) Turn rotor at low speed until vibration stops, then gradually increase speed to operating speed. If vibration continues, shut down, determine and correct the cause
5. Operating in Critical Speed Range Operate at other than critical speed
6. Build-up of Deposits on Rotor Clean deposits from rotor Check balance
7. Build-up of Deposits in Diffuser Mechanically clean diffusers
8. Unbalanced Rotor Inspect rotor for signs of rubbing Check rotor for concentricity, cleanliness, loose parts Rebalance
9. Damaged Rotor Replace or repair rotor Rebalance rotor
10. Loose Rotor Parts Repair or replace loose parts
11. Shaft Misalignment Check shaft alignment at operating temperatures Correct any misalignment
12. Dry Gear Coupling Lubricate coupling
13. Worn or Damaged Coupling Replace coupling Perform failure analysis
14. Liquid “Slugging” Locate and remove the source of liquid Drain compressor casing of any accumulated liquids
15. Operating in Surge Region Change operating point
16. Insufficient Flow Increase recycle flow through machine
17. Change in System Resistance due to Obstructions or Improper Inlet or Discharge Valve Positions
Check position of inlet/discharge valves Remove obstructions
18. Compressor not up to Speed Increase to required operating speed
19. Excessive Inlet Temperature Correct cause of high inlet temperature
20. Leak in Discharge Piping Repair leak
21. Vibration Probably imbalance or coupling. Refer to IMI Candidate Manual, or other references.
22. Sympathetic Vibration Adjacent machinery can cause vibration even when the unit is shut down, or at certain speeds due to foundation or piping resonance. A detailed investigation is required in order to take corrective measures.
23. Improperly Assembled Parts Shut down, dismantle, inspect, correct
24. Loose or Broken Bolting Check bolting at support assemblies Check bed plate bolting Tighten or replace Analyze
25. Piping Strain Inspect piping arrangements and proper installation of pipe hangers, springs, or expansion joints.
26. Warped Foundation or Bed plate Check for possible settling of the foundation support
Correct footing as required Check for uneven temperatures surrounding the foundation casing
27. Faulty Lube-Oil Pressure Gage or Switch Calibrate or replace
28. Faulty Temperature Gage or Switch Calibrate or replace
29. Oil Reservoir Low Level Add oil
30. Clogged Oil Strainer/Filter Clean or replace oil strainer or filter cartridges
31. Relief Valve Improperly Set or Stuck Open Adjust relief valve Recondition or replace
32. Incorrect Pressure Control Valve Setting on Operation Check control valve for correct setting and operation
33. Poor Oil Condition/Gummy Deposits on Bearings Change oil
Inspect and clean lube-oil strainer or filter
Check and inspect bearings
Check with oil supplier to ascertain correct oil species being used
34. Inadequate Cooling Water Supply Increase cooling water supply to lube-oil cooler
Check for above design cooling water inlet temperature
35. Fouled Lube-Oil Cooler Clean or replace lube-oil cooler
36. Operation at a very Low speed without the auxiliary oil Pump
Running (if main L.O. pump is shaft driven)
Increase speed or operate auxiliary lube-oil pump to increase oil pressure
37. Bearing Lube-Oil Orifices Missing or Plugged Check to see that lube-oil orifices are installed and are not obstructed
Refer to lube-oil system schematic diagram for orifice locations
38. Oil Pump Suction Plugged Clear pump suction
39. Leak In Oil Pump Suction Piping Tighten leaking connections
Replace gaskets
40. Failure of Both Main and Auxiliary Oil Pumps Repair or replace pumps
41. Oil Leakage Tighten flanged or threaded connections
Replace defective gaskets or parts
42. Clogged or Restricted Oil Cooler Oil Side Clean or replace cooler
43. Inadequate Flow of Lube-Oil If pressure is satisfactory, check for restricted flow of lube-oil to the
affected bearings
44. Water in Lube-Oil Probably a steam leak condensing in bearings or lube-oil cooler leak.
45. Leak in Lube-Oil Cooler Tube(s) or Tube Sheet Hydrostatically test the tubes and repair as required
Replace zinc protector rods (if installed) more frequently if leaks are due to electrolytic action of cooling water
46. Condensation in Oil Reservoir During operation maintain a minimum lube-oil reservoir temperature of 120°F to permit separation of entrained water
When shutting down, stop cooling water flow to oil cooler
Commission lube-oil conditioning unit
Refer to lube-oil management guide

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