Pump Vibration Issue

[siiruy]

Guys!

Just trying to figure out about the vibration on one of the installation onboard.

the alligment between motor and pump, pump and pipes is ok.

the foundation is up to standard. all stiffners are in order. Still, i have quite significant vibration.

i haven't open up th e pump yet to check the impeller and everything, but anybody coul please advise me the area which i should cover in trouble shoot this problem?

Thanks ..

 

[Artisi]

Is this something that has "just" happened or has it been a gradual build-up.

Is there any noise associated with the vibration?
Could be the pipework at its natural frequency.
Is it the pump vibrating or the driver (it always seems to be a faulty pumps - never the driver)

If the installation is correct I would be investigating:
A hydraulic problem.
A foreign object lodged in the impeller
A broken vane

More detail from yourself might also help.

 

[JJPellin]

In my experience the most common causes of high vibration in a pump are: Mechanical Imbalance, Misalignment, Run-Out (bent shaft), Rubs, Cavitation, Bearing Failure, Coupling Failure, Looseness, Hydraulic Imbalance, Resonance, Whip, Whirl or Plugged Passages. Each of these, in turn, could have several different manifestations. You could do a detailed analysis of the vibration: spectra, wave forms, phase relationships, housing vibration, shaft deflection. Or you could disassemble the pump and perform a detailed inspection.

Johnny Pellin

 

[siiruy]

Thanks Artisi for your advise.
Below is the answer for question you ask;


Is this something that has "just" happened or has it been a gradual build-up.
==> gradually build up, i believed. i've done workshop testing befor we installed and nothing wrong with that pump.

Is there any noise associated with the vibration?
==> humming noise but not very significant

Could be the pipework at its natural frequency.
==> the pipe is intact... i don't see pipework problem.

Is it the pump vibrating or the driver (it always seems to be a faulty pumps - never the driver)
==> definately the pump.

If the installation is correct I would be investigating:
A hydraulic problem.
==> not sure what you mean here.

A foreign object lodged in the impeller
A broken vane
==> yes, this is what i think. by the way, it is sea water pump direct suction from my sea chest. there is duplex strainer, but i still think about possibility of foreign object damaging the impeller.

 

[Artisi]

What pump style are we discusing - end suction, double suction, vertical lineshaft turbine etc.

Hydraulic problem = partially blocked inlet /strainer, a valve in the system partially closed, increased or decreased system requirement etc etc.

Might be time to open the pump for an inspection.

 

[siiruy]

Thanks JJpellin,

Artisi,

it's a normal 4x3x13 horizontal centrifugal pump.

hydraulic problem ==> i don't think so, due to independant seachest suction.

anyway, just give order to inspect the pump impeller and do the balancing check. crossing my finger

 

[Artisi]

Lets us know the outcome.

 

[siiruy]

Gents!
After complete inspection, the first thing we notice is the impeller chipped significantly.

this is due to defective MGPS system which allow shells alike went inside the system and .... it's like sand blasted.

Not only the pump, but all the valve is also affected.

Cheers,

 

[Artisi]

any photo's of the damage?

 

[BigInch]

What did the strainer look like?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

What strainer

 

[BigInch]

The one he's going to install now.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

Oh! that one.

 

[BigInch]

Not that one.

THIS BIG ONE!!!!

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

Now that's a nice looking strainer - that's of course if you are into strainers.

 

[BigInch]

Well, you could "get into" that one!

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Artisi]

It is probably big enough for the OP's 4x3x13 pump