Vertical pumps
Vertical pumps
(OP)
What is the best way to determine what frequency you can expect to see excited when a spider bearing wears out on a vertical turbine?
Thanks,
Texark
Thanks,
Texark
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RE: Vertical pumps
Walt
RE: Vertical pumps
RE: Vertical pumps
Walt
RE: Vertical pumps
Thanks for your reply.
A scenario would be this: Large sub-synchronous peak in data taken on the motor (pump shafts & bearings are inaccessible, as you stated). This peak is suspected to be shaft whip due to worn or missing spiders. What is the best way to verify this before recommending the expense of pulling the pump?
RE: Vertical pumps
RE: Vertical pumps
Is there an identical pump nearby for making comparison vibration measurements? How long has the pump been in service? Does the water being pumped have a lot of silt or sand or other abrasive material? Do the bearings have clean water flush?
I would conduct an impact test with impulse (load cell) hammer; instead of an ordinary hammer. The hammer size/weight with extender mass would depend on motor size (typically 2-lb to 12-lb sledge). The impact tip should be soft rubber (grey) to get low frequency energy. The impact and response should be in two directions at top motor bearing housing (parallel and transverse to pump discharge). A low frequency accelerometer with high sensitivity (500 mv/g) is helpful for low vibration levels. I conducted a similar test on two 600-hp 720-rpm vertical circulating water pumps (10,700-b motor and 13,190-lb pump)a few weeks ago with a 2-lb impulse hammer and extender mass. Fortunately I did not need the 12-lb sledge! Good vibration test (operating and shutdown) data can be very helpful for making the decision to schedule and remove pump.
Walter Strong
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