Several issues regarding pump vibration (this phenomenon may occur in various refineries)
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Vibration phenomena of mechanical pumps: 1. The deviation is only present in the vertical direction, or only in the horizontal direction； 2. Replacing the bearings during major repairs or even performing dynamic balancing does not resolve the issue of excessive vibration, as all relevant measurements are within acceptable limits ； 3. After eliminating mechanical issues with the equipment, the root cause of the problem may lie in the manufacturing process or the strength of the equipment’s foundation; therefore, solutions are urgently needed. Such phenomena should exist in all refineries, and we urgently need the guidance of experts to discuss the possible causes of these failures as well as solutions!
When aligning your pump, were the screws of the coupling tightened in advance? If so, it’s fine for large pumps; but for small pumps, alignment will have an adverse effect, causing the equipment to vibrate excessively. The solution is to center the wheel when it is completely loose, then lock it, and check how the vibration behaves. I hope this can help you
Send a picture of the entire device to show what it looks like, indicate the locations where vibration occurs, and preferably include the pipes nearby; the more information, the better. Is this phenomenon acquired or innate?
Start by considering the following aspects: 1. Check whether the vibration detection instrument is functional, sensitive, and accurate, and verify that the data it provides is correct; it’s best to also analyze the spectrum. 2. In terms of mechanics, focus on checking the clearance between mating parts, examining the stress in the connecting pipes, and addressing issues related to rotor dynamic balance. By taking into account the relevant installation and maintenance procedures, instructions for use, as well as the manufacturer’s recommendations, it is necessary to address the issue of rotor dynamic balancing here. Before carrying out dynamic balancing, certain technical requirements must be met, including the performance of the balancing machine and the precision required for achieving balance; this implies that technicians need to have knowledge of rotor dynamic balancing. 3. Basic questions ； Foundation strength, stiffness, and uneven settlement are issues that arise frequently in refineries located by the sea due to foundation settlement. Uneven foundation settlement can cause slight elastic deformation of the pump and drive motor housings, affecting the operation of the rotor system and leading to vibration problems. 4. Process-related issues: Common process factors that cause vibration in pumps include cavitation and vaporization. These issues are relatively easy to diagnose by checking the vibration of the pump body, the noise from the pipes and the pump body itself, whether there are fluctuations in outlet pressure, and whether there are variations in motor current. 5. Regarding the design and operation of the pump, it is necessary to check whether the pump’s operating conditions deviate from those specified in the design. Vibration levels certainly change under conditions of low or high load; API610 can be used as a reference for this purpose.
Vibration of the equipment when it is running idle is usually due to installation issues. The equipment is rotating under load; if the medium is gas, it could be a sealing issue ； If the medium is a liquid, it could be caused by cavitation. Additionally, unstable loads can also cause equipment vibration.
Generally, for such vibration anomalies, issues such as the concentricity of the pump, the tightness of the bolts in various parts of the pump, the clearance between different components, and the dynamic balance of the rotor are all checked to rule them out
:Handshake: For such vibration anomalies, issues such as the concentricity of the pump, looseness of the bolts in various parts of the pump, clearance between different components, and rotor dynamic balance are all checked and ruled out. From a process perspective, conditions such as vacuum formation, cavitation, and flow rate deviations are also eliminated. What we want to know now is that some pump units show no abnormalities in various inspections; the excessive vibration is only present in the vertical direction, while the horizontal and axial levels are normal ； Either the horizontal level is out of spec, while the vertical and axial levels are normal. What are the common reasons that might lead to this situation?
We have a diesel-driven fire pump here; during trial operation, it was found that the axial vibration levels were above the acceptable range, while the horizontal and vertical vibrations were relatively normal. Further inspection revealed that the misalignment between the universal joint couplings was approximately 2 cm. After making adjustments and reinforcing the steel structure base with grout, the vibration levels returned to normal
Today’s testing methods are very advanced; spectral analysis can help resolve many issues related to vibrations. Problems such as dynamic balance, the angle of the rear wheels, soft foundations, and bearing issues can be addressed, and it is even possible to identify the cause and location of the fault