Centrifugal pumps - Best practices 2

[JKALLPA]

Hi:

I'd like to share experience on preventive maintenance of centrifugal pump, We could talk about mechanical and electrical jobs like:

- Lubrication of bearing housing.
- Bearing motor greasing.
- Vibrations measurement
- Adjustment clamp bolts and cleanness.
- Checking power consumption.

Checking alignment is a good practice if you measure vibrations every 3 months, I mean we have 2 pumps os i f you check alignment it takes like 1 hour depend on the technician so once of then has to be stand by, it is a huge risk if the another once fail.

To check desalignmet doing just vibrations measurement would be easy? Or we need an experience engineer to detect it?

Jorge

 

[JJPellin]

You didn't provide much detail about the types of pumps you work with. But, I will comment on the practices we use in a large oil refinery.

We have approximately 2000 pumps. About 1600 of them are centrifugal. Most of those are set up in pairs with one pump running and one pump on stand-by. The average size of our pumps is about 80 horsepower.

We normally change the oil in the pump bearing housings twice per year.
We add grease to the motor bearings twice per year, as well.
We take vibration data on running pumps once per month. We have a policy that requires us to take vibration data at least once every three months. So, the spare pumps must be run at least that often to allow us to take vibration data.
When the mechanic changes the oil, they do a general inspection of the entire machine train including the coupling, coupling guard, lubricator, etc.

We do not routinely check coupling alignment. We have enough confidence in our vibration program that it will catch misalignment and alert us of the need for correction. Checking alignment requires removal of the coupling guard, application of energy control, issue of a safe-work permit. This would be a substantial investment in time. And, properly installed equipment should not require periodic re-alignment.

A good vibration program requires a trained technician to evaluate the data. It is not necessary to have an engineer on staff for this evaluation. There are good training and certification programs for vibration technicians available through the Vibration Institute in the US. I am sure that there are similar organizations in many other countries.



Johnny Pellin

 

[JKALLPA]

It was a good information, What about bearings? We have some motor which has no sealed bearings... it is a good practice to change them for ZZ or 2RSL bearings? The majority are working without enclosures so the weather will be a big problem.

I'll receive next month my vibration meter, at the beginning I'll try to make my planning as well you wrote. I know We have several problems on many pumps, my commissioning department didn't work in a good way. I'm working on 3x1 combined cycle plant ( 870 MW) and I want to make the best maintenance planning for my pumps.

Jorge Cárdenas

 

[JJPellin]

We only use sealed bearings in very small motors (5 HP or less). Our environment is very cold.

Johnny Pellin

 

[JKALLPA]

What about electrical preventives? Have you got a plan?

Thermography, insulation measurement, checking power consumption... I'd like to know it.

Regards,

 

[JJPellin]

I have no involvement in electrical PM programs. I know that they use thermograph, but I don't know the details. I believe that they "megger" some equipment to verify insulation integrity. But, once again, I don't know the details.

I am involved in evaluating performance on our largest and most critical pumps. One part of that monitoring is to measure power consumption in the form of amp draw.

Johnny Pellin