I have a turbine driven feed water pump that has a 1/2 times turning speed spike that just showed up in the last survey. My question is what parameters I should use to collect orbital data with accelerometers. I realize this is not the proper way to collect orbits but the turbine does not have proximity probes and I am trying to get an idea on what the problem may be. I am using a CSI 2130 and RBMware.
It is a sleeve bearing turbine running at 3570 rpm.
Any suggestions?

Thanks, Ken

You're stating the problem or 1/2X is in the pump: what type bearings are in the pump? Is there a tach/key phasor output that monitors RPM that you can plug-in to? And, direction of rotation?

Sam,
The 1/2 times is in the turbine, now as far as direction of rotation I will have to get back with you on that. I just recently took over this area and I am not very fimiliar with the equipment.

Thanks

Ken,

Take PeakVue waveform and spectrum and see if the 1/2 is in there. I would be concerned with a possible rub. Any work done on this unit lately?

thanks

Bill,
I'll give that a shot.
I have attached the orbit I collected yesterday, it is showing 4 revolutions of the shaft. Looking at it I think it is a rub; I am just not sure if my setting are correct.

Thanks

This_orbital_plot_is_showing_4_revolutions_of_the_shaft.doc (44 Kb, 69 downloads)

You need to be careful of reading too much into a bearing housing orbit, it is not the same as a rotor orbit at all.

The orbit you posted does not really tell me much at all about what is going on with the machine.

If the spectrum has a pure 1/2X that might be a rub, it might be looseness, it might be a reexcitation of the 1st critical due to fluid instability as well. Without a real shaft orbit from a set of prox probes it will be difficult to tell.

Steve,
I collected more vibration data and it does appear to be a true 1/2x. I spoke with the Production and Maintenance foremen and told them the same thing, without prox probes I cannot be sure exactly what might be wrong with the turbine. They informed me that this unit is scheduled for rebuild in the early part of next year. As a precaution they shut it down and put it on standby.
Thanks for everyones help.
Ken

Ken,

Are you going to see about adding prox probes when the unit is down for rebuild?

Skip

I am suggesting it, but you know how that goes sometimes.

Might go poke around and make sure eveything is tight, especially bearing caps etc...