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RustyCas

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Reply with quote  #1 
Seen a lot of crazy things in my career, but nothing quite like this. This is a Dodge Sleevoil bearing on a 1500 hp, 16,000 lb center-hung fan.

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ssimmon1

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Reply with quote  #2 
That's some impressive neglect!
MachDiag

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Reply with quote  #3 

I have some power generation customers that have fans with these bearings, but I've not seen any with that recessed tuna fish can located a 180 degrees in your picture (not sure what that feature is).   

That one appears to be a water cooled unit.  What's the shaft size?

>>> Edit... When first viewed, the screen size on my device was quite small and Rusty's photo image even smaller.  I can clearly see now, what I couldn't see earlier.   Yeah..., well okay so that tuna fish can I inquired about is actually the fan shaft [rolleyes].  
 
But, I have seen an instance like this one.  So time back, I did have have a customer call me wanting me to balance their I.D. Fan.  Said it was shaking so badly that sparks were coming out of the inboard fan bearing.  I mentioned they probably have a mechanical issue that needed to be dealt with first.  They called back later saying that when they had split the coupling, the fan shaft fell down about 1/2".  I later balanced it, after repairs were completed.          

Danny Harvey

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Reply with quote  #4 
Ted,

I'd say the shaft is about the size of a tuna fish can.

Rusty,

I have seen worse but on a rolling element bearing at higher speed and a much smaller rotor.

I would guess that this was a lack of lube and once the bearing is wiped, it progresses pretty fast through the soft cast iron.
OLi

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I have a example from a customer that "claimed" no bearing condition alarm on a new route collector as the ballbearing was converted to a water lubed bearing with no rotating balls at all.
Similar but with grease lubed and no rotating balls, called to "balance". Generator w/o any balls left inside, called to "balance". That for antifriction bearings not so common on the others.

Turbine bearing and bad steam seal so oil carbonized, shaft dug in to bearing, turbine rotor contacted stator and failed dramatically.

Neither of the above went that far.......


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Walt Strong

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Reply with quote  #6 
Seen it! 8000-hp ID fan with shaft that cut through journal bearing housing and about 18" of steel bearing support pedestal and came to rest sitting on the concrete foundation. It was reported that lube oil system had failed!

Walt
Danny Harvey

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Reply with quote  #7 
I know a colleague who spent some years working as a maintenance mechanic in a papermill and one of his jobs was maintenance of the lube systems for the turbines.  He was meticulous in how he did it and it never gave them any problems.  

He retired and nobody took the job over because it was so low on the list of things to do.

It quickly moved itself way up the list when a clogged filter (or some other seemingly trivial component failure) shut down the oil flow to a bearing.

External lubrication systems, no matter how small, are critical if they lubricate critical equipment.  There's not much glory in keeping the systems working right but there's always plenty of excitement when you don't.
Danny Harvey

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Reply with quote  #8 
Walt and Rusty,

How long do you think it took to go from good to what you guys saw?

In my case I found the bearings (double row spherical rollers in a pb housing) bad enough to walk off my route to tell the supv. in August.  When I returned in Feb. of the next year, there was no bearing left except a little ring from the cage and the inner race. But still running.

But that rotor was about 3540 rpm and only about 300 lb.

I would imagine that at 10-15 tons with no oil pressure the relatively hard shaft eats away pretty quick through the babbit, the cast iron and then the steel.
Walt Strong

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Reply with quote  #9 
Danny,

Perhaps about 5-8 hours of the length of the night shift.

Walt
fburgos

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Reply with quote  #10 
Never seen something similar
electricpete

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Reply with quote  #11 

Dang, it looks like the bearing failed and the shaft kept spinning and spinning… eventually wore down through the bearing and the housing. I wonder how long it took it to do that. 

That is impressive all right. Never seen anything like it.

RustyCas

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Reply with quote  #12 
Vibration went high, but the fan's PLC had lost communications with the master PLC in the MCC.  At some point in time, the command which would shut the fan down if communications was lost was disabled.  So there were no vibration alarms seen, and no trip initiated.  I'm not sure what the vibration "readings" were on the operators screen, but other than on day shift, those screens are not monitored.

This was a holiday weekend, so no one around and the fan just kept running.  Once it ate through the liner into the water jacket, there was a flood of cool water to keep it lubricated and cool.  They actually found the problem when they investigated the cloud of steam coming from the outboard end of the fan.  As you might guess, the gear coupling on the other end was destroyed (and maybe the inboard fan bearing).

The crazy thing is, the same thing happened about 6 weeks ago and the bearings and fan shaft had to be replaced.  And that fan had only been in service for about 4 months.  So this will be the 3rd rebuild in the last 6 months.

But, hey, the IOT is going to fix all this stuff, right?  It's all way better than a bunch of hard-wired relays and contacts, right?

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Walt Strong

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Reply with quote  #13 
Add Id to IOT and get Idiot!

They need a  vibration monitor that when an alarm occurs, it reaches out and grabs an operator and pulls him/her closer to machine for attention!

Walt
fburgos

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Reply with quote  #14 
Quote:
Originally Posted by Walt Strong
Add Id to IOT and get Idiot!

They need a  vibration monitor that when an alarm occurs, it reaches out and grabs an operator and pulls him/her closer to machine for attention!

Walt


But what to do with asimov laws of robotics?
OLi

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Reply with quote  #15 
If you as operator see 200 mm/s reading on a fan in the monitoring and only write a work order to get it fixed not noticing any alarms in the process previously I would say in the best world, some training would be suggested. Done that. I would say autolubers are better than no lube, minimum it extend the pain a year and then some. I think in general that on the size of things I work that emptying a canister per year is about enough, "lagom". Lube tracking systems also work, even better, that register how much grease every zerk got and when. 
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