Abstract: In pump body faults, the diagnosis of pump bearing faults is representative. The spectral analysis method of vibration diagnosis is very meaningful for the fault diagnosis of rolling bearings. Two examples, the 5 # water pump and the P60A spray pump, were listed for explanation in the oxygen plant of Benxi Iron and Steel.
Keywords: pump; Bearings; Diagnosis; analysis
1 Preface
Water pump equipment is widely used in enterprise production, and the main maintenance methods used today are: first, regular maintenance. Regardless of the operating condition of the equipment, parts are replaced at a certain cycle. This maintenance method ensures the good operation of the equipment, but the economy is poor. The second is post maintenance, which maximizes the service life of equipment components, but can easily cause damage to other parts of the equipment body. The current equipment vibration diagnosis technology has gradually matured, and equipment management personnel can use advanced methods to achieve controllable equipment status and extend the service life of components.
2 Actual Case Analysis
Our factory has been conducting precision inspections for many years, and has also achieved initial results in spectrum analysis, which has played a positive role in extending equipment maintenance cycles and avoiding sudden equipment failures. Below is a brief analysis of two water pump bearing faults in our factory using the HY-106 vibration meter.
2.1 Case 1: Fault Analysis of 5 # Water Pump Bearing
2.1.1 The layout of measurement points for the 5 # water pump is shown in Figure 1.
Figure 1 The layout of measurement points for the 5 # water pump
2.1.2 Basic parameters of 5 # water pump
Water pump model: 600S-75A
Flow rate: 2950m3/h
Lift: 65m
Speed: 970r/min
Impeller stage 1
The bearing models on both sides of the pump body are 6320.
2.1.3 Measurement point number: Non load side bearing of pump body acceleration
Sampling time: 2012-05-0309:52:13
Measurement value: 303.4m/s2. The collected spectrum and trend plots are shown in Figure 2 and Figure 3, respectively.
Figure 2 Acceleration spectrogram
Figure 3 Acceleration value trend chart
2.1.4 Measurement point number: Non load side bearing of pump body velocity
Measurement value: 13.3mm/s. The collected spectrum and trend plots are shown in Figure 4 and Figure 5, respectively.
Figure 4 Acceleration spectrogram
Figure 5 Acceleration value trend chart
2.1.5 Diagnostic conclusions and recommendations
In the test of the non load side bearings of the 5 # water pump at the 8 # water pump station, we found that the acceleration and velocity values significantly increased. In the vibration monitoring of the pump body, it was found that the velocity value was 5.4mm/s from the monitoring on March 2, 2012, indicating poor lubrication. We require the user to strengthen lubrication and pay attention to observation. In the spectrum inspection in April and May, it was found that the degradation was significant and increased to 13.3mm/s. At the same time, it was found in the spectrum that the inner ring passing frequency was obvious and there was a fourth harmonic, accompanied by the inner ring passing frequency. The overall degradation of the bearing was severe, and the inner ring failure was severe. It is recommended to stop the operation of this equipment, check the wear and tear of the equipment, and replace the bearings. (Bearing model 6320)
2.1.6 Maintenance feedback
On May 4, 2012, the machine was shut down for maintenance, confirming the correctness of the diagnostic results. After replacing the spare parts at the same time, the two speed values were measured to be 1.6mm/s.
2.2 Case 2: Analysis of bearing failure in P60A spray pump.
2.2.1 Basic parameter description
Model: XA50/26
Flow rate: 65m3/h
Lift: 91m
Speed: 2930r/min
Impeller stage 1
Pump body load side bearing model 6305E
Pump body non load side bearing model 7305B
2.2.2 Measurement point number: Pump body load side bearing speed
Sampling time: 2012-11-1413:19:24
Measurement value: 8.2mm/s, the collected spectrum is shown in Figure 6.
Figure 6 Load side bearing spectrum diagram
2.2.3 Measurement point number: pump body non load side bearing speed
Measurement value: 6.2mm/s, the collected spectrum is shown in Figure 7.
Figure 7 Non load side bearing spectrum diagram
2.2.4 Diagnostic conclusions and recommendations
In this vibration diagnosis of the spray pump body of Unit 5, and analysis of the bearing vibration on the load side of the pump body, the speed value reached 8.2mm/s, which was too high, and the acceleration value overflowed. The spectrum observation shows that the inner ring of the bearing has a higher frequency doubling component at 97.5Hz. The problem with the inner ring of the bearing is severe. Bearing model (6305E). At the same time, in the analysis of the vibration situation of the non load side bearing: the speed value reaches 6.2mm/s, which is too high, and the acceleration value overflows. The spectrum shows that the inner ring of the bearing has more harmonic components passing through the frequency spectrum of 100.5Hz. The problem with the inner ring of the bearing is obvious. Bearing model (7305B). It is recommended to stop the operation of this equipment, check the wear and tear of the equipment, and replace the bearings.
2.2.5 Maintenance feedback
This maintenance was carried out on November 16th. After disassembly, no faults were observed in the two bearings from the appearance. At the same time, the bearings were rotated smoothly by hand and there were no abnormalities. The replacement time for the two bearing models 6305E and 7305B is less than a week. The construction unit replaced the bearings and shafts of this pump as a whole.
With the support of theoretical data, it was required to disassemble the two replaced bearings, and it was found that there were many grooves in the inner race of the two bearings, which verified the correctness of the diagnosis. After replacing the new bearings at the same time, the data of the bearings on both sides were measured to be 3.0mm/s and 2.1mm/s, respectively. The equipment is running well. The quality of the original bearing spare parts is poor.
3 Conclusion
Through the above two cases, we have gained an understanding of diagnosing faults in pump type equipment. Including trend analysis, velocity spectrum analysis, acceleration spectrum analysis, etc., in the case of rolling bearings, the early fault acceleration response is obvious, and the mid to late fault acceleration response is obvious. In the second case, the inner ring corresponding to the bearing library has a higher frequency doubling component and a larger secondary value. With the development of technology, equipment spectrum analysis has become increasingly mature in fault diagnosis of rotating machinery, and predictive maintenance has gradually become a trend in refined equipment management. Make the operation status of rotating equipment truly "controllable" and "controlled".
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2024-05-31