The centrifugal pump vibrates severely; seeking help
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One of our units has a centrifugal pump of model 200AYS250, operating with aromatic compounds as the medium at a temperature of 180°C. After three years of continuous operation, the radial bearing 6213 started to seize the shaft. During maintenance, the pump shaft and the bearings at both ends were replaced. Four hours after the maintenance was completed, the radial bearing seized again; further maintenance was carried out, involving the replacement of the pump shaft and the bearings at both ends, as well as performing dynamic balancing on the rotor. The pump has now been in operation for five days, but there is significant vibration at the thrust end. The lubricating oil becomes cloudy within one or two days, and copper particles are present in it. We are unable to determine the cause at present; please help us analyze it
Possible reasons for the seizure of radial bearings include whether the clearance between the bearing and the shaft, as well as the clearance between the bearing and the bearing housing, meet the specified standards； Bearing quality issues, alignment problems (under operating conditions)
Based on your description, it seems to be caused by poor assembly.
The presence of copper filings indicates that the bearing cage is rubbing against the rollers or the inner and outer rings under additional loads, which leads to poor lubrication, loss of clearance, and subsequent overheating and seizure； Therefore, it is important to check for shaft bending and excessive shaft runout, as these can all lead to bearing misalignment and thus vibration problems.
It’s impossible to determine the cause at the moment; replacing the pump, replacing parts, and aligning the shafts – it’s all very troublesome
Better pump shafts and bearings – is there any measurement of the clearance? It seems to be a replacement imitation shaft. Are C3 bearings being used, or did you just mention 6213 bearings? According to the instructions, it seems that the axial thermal expansion of the shaft causes axial displacement of the bearing.
1. Check the bearing assembly clearance. 2. Due to bearing quality issues, it is recommended to try using bearings from another brand. 3. Regarding alignment issues, if alignment is not properly done, excessive vibration will occur; the likelihood of shaft seizure is very low. Personally, I think the first question is more likely to be the case; if the original poster solves the problem. Please tell me the reason, thank you!
Personally, I think it’s a problem with your assembly and installation; the friend on the 9th floor explained it in quite detail.
It may be that the clearance reserved for axial expansion is insufficient