Dear All,

can any one support me in this problem:

we have one Siemens compressor centrifugal single stage integrally geared

observed a high vibration in radial tilting pad bearing in pinion shaft compressor side without any changes in axial displacements?

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Actions for inspection:

*IGV & Impeller are ok but found amount of water insuction spool passing from the demister.

*Gears teeth & backlash are ok.

*Clearances are checked for Radial tilting pad bearings of pinion shaft and found:

comp side: out of permissible range by 0.07 mm

motor side: equal to max range

*shaft runout is ok

*axial displacements are ok for both shafts.

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Q1.  What is the clear effect of water to the comp performance?and  how can be observed thru vibration monitoring?

Q2.   Is bearing clearance root cause or result?

Q3.  Do anyone know about adding shims below the top pads of the bearing to adjust the clearances in case of unavailability of spare pads????

ready to share more information about the case....

thanks in advance :-)

 

 

Regards,

Mechanical Mostafa

 

Original Post

I think that:

Q1.  What is the clear effect of water to the comp performance?and  how can be observed thru vibration monitoring?

The water in air/gas will effect to comp performance (changing density of gas/air) and it depends on how many water in. In my experience, one of effect you can see when you inspect impeller is erosion/corrosion on surface of impeller.

I have no experience with much water in gas so I do not know how it is. However, I think that if the water in gas too much, it will damage to machine (water is not able to be compressed)

Q2.   Is bearing clearance root cause or result?

The clearance is not the same on both side of bearing could effect to vibration and off course if it is like you said the vibration could be high. you can check the orbit, shaft centerline and waterfall to see how much it change.

One of other cause I have met, it is related to alignment of bearing housing, especially, to integrated gear compressor.

Q3.  Do anyone know about adding shims below the top pads of the bearing to adjust the clearances in case of unavailability of spare pads????

you can insert shim under back of pad (pivot location) but be careful to avoid looseness of shim. I would like to see how the pad look like.

Hope that help.

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