Vibration in the pump outlet pipeline
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The outlet pipeline of a circulating hydrocarbon pump installed at this facility experiences severe vibration; the flow rate is 450 m3/h and the outlet pressure is 0.5 Mpa. Damping measures such as shock-absorbing bends and spring supports have been installed at the outlet site, but the vibration remains severe. Experts from various fields are requested to provide technical support!
Check the alignment of the coupling, as well as the condition of the pins or buffer rings； Whether a change in dielectric density causes overloading ； Are the foundation bolts loose? ； Check whether the inlet valve is damaged and whether the inlet pipe is blocked ； Pump evacuation or cavitation ； The pump shaft is bent or the impeller is unbalanced ； The impeller is loose or the key has failed ； Is the bearing damaged? ；
First, please determine whether it is pump vibration or pipeline vibration. If it is pump vibration, consider the pump alignment or the base; it could also be due to deformation of the pump body. Vibration spectrum analysis would be ideal. If it is pipeline vibration, it may be caused by pump vibration or by the fluid. It requires analysis based on specific circumstances.
Is the flow velocity at the pump outlet too high? Are there many elbows?
Is it the first run, and have there been any changes in the process parameters?
Is there stress in the pipeline? What is the condition of the pump foundation? Are there any issues with the pump itself? Do the process parameters of the medium meet the requirements? Is the pump pressure high?
Some pipelines experience significant vibration during normal operation; in such cases, more fixing brackets can be used； Also, if the medium in the pipeline contains water, it vibrates as well.
The vibration problem of mechanical pumps is indeed a complex issue. Over these two years, our company has indeed made efforts in addressing the problems with this pump. 1. Problems with the pump itself. This pump is a product of a well-known domestic company. Hydraulic models of pumps of this size were not common when the system was first installed in 2016; in October 2018, during a major repair of this pump, it was found that it had a single impeller and only 4 flow channels. With such a high flow rate, the design of the impeller in this type of pump can lead to water hammer effects, which may be the main cause of vibration in the pump. 2. Pipeline layout. Since this device is a modification of the original one, the pipeline layout on site is rather chaotic. By comparing with the pipeline layouts of other companies, their pipelines generally have a high inlet and high outlet position, with fewer elbows. The export pipeline of our company rises and then makes an S-shaped turn back to the ground, which increases the resonance effect. Solution: During the maintenance at the end of 2018, the horizontal section of the S-bend in the outlet pipeline was extended outward by 1 m, which reduced vibrations after operations resumed. The above is only a brief overview of the process for handling this issue; if there are any questions, feel free to continue the discussion. Thank you all for your suggestions!
What size should be used for the inlet and outlet pipes? Please send over the design parameters