Hi to all,

I need your help to sort out this case.A vertical centrifugal pump.High pipe line vibration up to 35.7 mm/sec in the direction of flow.And one more thing when M21PU4 is running this vibration in pipe is less than vice verse.
Naming is mention in attached file.
Motor 1480 r/min
55kW

Pump Cap. 480 m3/ hr
Pressure head 28 m.


If any other info is required,will be provided.

Bump test readings are taken in operating condition of M21PU5.

Resonance_case.doc (3,012 KB, 41 downloads)

Following up on your resonance ideas:

Assuming you cannot shut down the pump for bump test, it would be helpful to compare two spectra: one while bumping and one while not bumping. The difference of these two would represent vibration due to bumping.

Also might be helpful to map magnitude and phase along the pipe and around the circumference of the pipe to visualize the operating deflection shape and directionality.

Also might be helpful to try temporary bracing to see if that changes the vib.

How high is vib on running pump (pump itself) ?

This message has been edited. Last edited by: electricpete,

I am attaching the bump and non bump spectras.At this time Pump was off and its stand by was running.
MTR NDE VV(At top,in direction of flow) = 7.1 mm/sec

MTR NDE HV(across the flow) = 5.9 mm/sec.

It is a direct mounted pump, no coupling in it.
I am attaching all spectrums with this readings.

Bump_data.doc (572 KB, 16 downloads)

Q: Has anyone insight in pipeline vibs vs. mechanical stresses on the welding of the pipelines?

I think the thick green "shock and vibration handbook" had a table or chart with recommended allowable or permissible piping vibration. Maybe 0.1 ips max or something similar. And it had a big disclaimer that the mechanical details of the piping fabrication and operating conditions really need to be evaluated as part of a real stress analysis