changing white metal bearings 1

[Feg]

Guys
Looking for some tips on changing the white metal bearings on motors we have in service on turbo compressors which have a lot of hours on them. This is a precautionary measure as the main motor had a bearing failure a few months ago and it was decieded to change the bearings on the other one to try and eliminate this problem.
The motors are old SIEMENS IP55 frame 500 1200Kw 6.6Kv B3 foot mtd with Renk bearings with split cases, I have replaced these before but never in situ and am looking for some tips to help things run smooth as I will just have a short time to do this job.

Kind Regards

F.E.G

 

[edison123]

White metal bearings have a long life provided you had the right amount of oil and there is no delamination of the white metal from the shell. I would do UT on the old and the new bearings to check for delamination.

Replacing the bearings in situ should not be a problem. Decouple the motor, drain the oil from the housing, remove the top shell, jack the shaft at the end you want to change the bearing, slide out the bottom bearing shell, slide in the new bottom bearing shell, lower the shaft, fix the top shell and refill the with new oil. This is assuming that the new bearing is a direct one-to-one replacement. Always source the new bearings from the OEM.

 

[Feg]

Hi Edsion,

This is as I remember doing them before, i was just checking to make sure there was nothing i had forgot as it is so critical to get it back on-line. The compressor co. fitted the wrong grade of oil in the bearings after a service last year hense the problem, they used the same oil as the compressor hense the failure. See image of damage. And yes I will be using original parts, I agree this is always best.

 

[edison123]

That sure is a nasty failure. The right oil is very important and again OEM's word is mantra on that.

Is the journal area of the shaft scored ? If yes, you need to grind down the journal area and machine the new bearing to suit the reduced diameter of the shaft.

Good luck.

 

[oldfieldguy]

It appears you have shaft damage, too, and it's probably NOT going to repairable in situ. It depends on how deep the scoring is.

old field guy

 

[electricpete]

Some thoughts for simple bearing replacment:
Check clearance bearing-to-housing and shaft-to-bearing.
Perform dry roll check or blue check for contact pattern
Perform 4-corners check for alignment.

As others said the shaft repair will be the hard part.

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[Thedroid]

Is the image you posted of the first bearing which already failed, or the one that you are changing as a precautionary measure?

Scraping those bearings is a lost art as far as I know. They use to do it on the synchronous motor pedestal bearings at my plant, but nobody knows how to do it anymore.

I've serviced several bearings similar to those, and it's amazing the amount of abuse they will take, as long as they don't get hot. We have RTD's fitted to the reservoirs of all the babbitt bearings in the plant to monitor temp.

 

[oldfieldguy]

I have scraped bearings in myself. It's a tedious job but makes the bearing last much longer. I always did it in a shop. Most of our shop folks didn't have the patience, knowledge or inclination to do the job right.

And old machinist/millwright or motor shop guy should be able to explain and show the process. It doesn't lend itself well to a written explanation without a lot of pictures.

old field guy