Typical faults and causes of centrifugal pumps

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Typical Failures and Causes of Centrifugal Pumps – Table of Typical Centrifugal Pump Failures
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1. No water output at all
2. Less liquid in the delivery area than expected
3. Low pressure gauge reading
4. The head-flow characteristic curve is different from the original one
5. Water used to fill the pump leaks before it starts operating
6. Excessive power consumption
7. Vibration present
8. Noise present
9. Severe leakage in the stuffing box
10. Short lifespan of the gasket
11. Severe leakage in the mechanical seal
12. Short lifespan of the mechanical seal
13. Short lifespan of the bearings
14. The pump overheats and gets stuck

Table 2: List of Causes of Centrifugal Pump Failures
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1. Incorrect calibration or improper assembly of measuring instruments
2. Air enters the pump during operation or air remains in the pump’s delivery system before startup
3. Too low rotational speed
4. Incorrect rotation direction of the pump
5. The delivery pressure required by the pump system is higher than the designed value
6. Too low head (including too high suction height)
7. Excessive amount of steam mixed in the liquid
8. Excessive leakage at the wear surfaces
9. Liquid viscosity exceeds what was specified in the pump’s design
10. The impeller or pump casing is partially or completely blocked by solids
11. Rough flow channels in the impeller or pump casing
12. Fin-like cuts, burrs, and sharp edges in the liquid flow channels
13. Damaged impeller
14. The diameter of the impeller after machining is smaller than specified in the drawings
18. Blockage in the suction pipe or pressure pipe
19. The check valve is stuck or blocked
20. The inlet filter is blocked by solid substances
21. The inlet filter is covered by fibers
22. Improper configuration of the suction pipe or pressure pipe
23. Problems with the design of the water intake tank
24. One of several pumps operating in series or in a combination of series and parallel configurations is severely affected
25. The water level in the water intake tank or reservoir is lower than the pump’s suction inlet
26. Too high rotational speed
27. The specific gravity of the liquid being transported is higher than expected
28. Impeller size is too large
29. The total head of the pump’s delivery system is higher or lower than expected
30. The centers of the pump and its drive mechanism are not aligned
31. Friction between rotating and stationary parts
32. Worn bearings
33. Improper installation of the packing
34. Incorrect specification for the packing
35. Excessive pressure on the mechanical seal
36. The sealing gland is too tight
37. Poor lubrication of the bearings
38. Deformation of the piping system, causing stress on the pump
39. The pump operates at its critical speed
40. Unbalanced rotating parts
41. Excessive lateral forces on the rotating parts
42. Insufficient distance between the outer diameter of the impeller and the baffle
43. Incorrect shape of the baffle
44. Dimensions of the suction pipe, discharge pipe, and pipe fittings are too small
45. Valves or valve discs in the system rotate, causing cavitation inside the pump prematurely
46. Bent shaft
47. The inner and outer diameters of the impeller are not concentric or perpendicular to its surface
48. Misalignment of components
49. Too low operating flow rate of the pump
50. Improper design of the base plate or foundation
51. Resonance occurs between the pump’s rotational speed and the natural frequency of the foundation along with other structural components
52. Worn bearings lead to component damage, causing the rotating parts to deviate from their center of rotation
53. Improper assembly of the bearings
54. Damaged bearings
55. Blockage in the water seal tube
56. Improper arrangement of the water seal ring in the stuffing box; the space created prevents the sealing fluid from functioning properly
57. Wear or damage to the shaft or shaft sleeve at the packing area
58. Faults in the cooling fluid supply for the water-cooled stuffing box
59. Excessive gap between the shaft and the pump casing at the bottom of the stuffing box
60. Contaminants or coarse sand in the sealing fluid
61. Eccentricity between the stuffing box and the shaft
62. Improper assembly of the mechanical seal
63. The specifications of the mechanical seal do not match the operating conditions
64. Internal misalignment of components, affecting the proper fit of the gasket and seal
65. The sealing surface is not perpendicular to the axis
66. Dry operation of the mechanical seal
67. Abrasive solids in the liquid come into contact with the seal surface
68. Leakage under the shaft sleeve due to damaged gaskets and O-rings
69. The inner hole of the bearing housing is not concentric with the tailwater
70. Damaged or cracked bearings
71. Excessive grease in the bearings
72. The lubrication system does not meet requirements
73. Improper bearing assembly: damage during assembly, incorrect assembly, wrong bearing model
74. Bearings are not lubricated
75. Dust enters the bearings
76. Water enters the bearing housing
77. Blockage in the balance holes
78. Faults in the balancing device
79. Too high inlet pressure
80. Too tight fit between the intermediate bearing and the bearing housing, resulting in axial loading and sliding
81. The pump operates without water, i.e., in dry operation
82. Air bubbles and steam present inside the pump
83. Too low operating flow rate
84. Severe misalignment among pumps operating in parallel
85. High pipeline stress, poor quality of the foundation, or inadequate repairs cause internal misalignment
86. Static parts are subjected to friction from rotating parts
87. Worn bearings
88. Insufficient lubricating oil
89. The rotating and stationary wear rings are made of the same material with identical physical properties