Why can’t shims be used under the pump head for alignment?
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The last edit to this post was made by 3983596_FPPZ on 2018-12-5 at 09:58. Why do many standards stipulate that during the alignment of pumps and motors, shims cannot be used under the pump for adjustment; instead, shims can only be used under the motor? What is the reasoning behind this?
The pump head is connected to the pipes, and alignment is carried out after the inlet and outlet pipes have been aligned without any stress.
Mainly, it is convenient to align the motor, with the pump body connected to the inlet and outlet pipelines
When the motor’s height couldn’t be adjusted, the pump head was adjusted as a last resort
The first is trouble. Second, using shims to align the pump head causes the pump body to bear additional external forces from the pipes.
Adjust the motor with the pump as a reference; using shims on the pump can easily cause vibration in the pump.
It’s not that padding can’t be used; it’s just that, comparatively speaking, the motor is more convenient. Adjusting the inlet and outlet of the pump head with padding is too troublesome, and in some cases grouting may even be necessary.
If the inlet and outlet pipes are rigidly connected, aligning the pump will increase stress
It’s possible, but it’s troublesome to add pads at the pump end – the pipes have to be removed
For flexible connections, it is acceptable if the motor height is too great; when using rigid connections, the stress exerted by the pipeline on the pump must be taken into account, otherwise it will cause vibration in the pump
In principle, once the piping for the pump has been installed, gaskets cannot be added under the pump feet during maintenance in production. This is because the flanges at the pump’s inlet and outlet are adjusted and fixed at this point to ensure the proper gap and concentricity with the pump’s inlet and outlet flanges; if shims are used under the pump feet, it can affect the concentricity or alignment of these flanges, and strictly speaking, it causes additional stress on the piping connected to the pump. Additionally, shims are placed at the pump feet; if there are a large number of these shims, the vibration of the pump or the pipelines can cause the shims to shift or create a spring effect, thereby increasing the vibration of the pump. Therefore, it is not recommended to add pads under the pump feet.