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Sinski

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Reply with quote  #46 
Quote:
Originally Posted by Ralph Stewart
ssimmon1,

David has a good point on the purging of the bearing.

Where I worked for some 38 years, we developed a "ritual" of manually greasing all bearings which were on grease, on our two, 400 to 850 fpm machines, , immediately after the machine was shutdown on every 28 day cycle for routine maintenance and/or clothing change.

The oilers were on the job pumping grease, as soon as the machine stopped turning, until the grease and water was seen coming out of the bearings. Not only does "water" get in the bearing from being located in the wet area of the machine, but also from the condensate that develops as the machine cools down when shutdown. This condensate gradually enters into the bearings while it is in a cool down stage during each shutdown.

Some may say that filling the bearings with that much grease could cause a heat problem, but with the forced hot air of 200+ degrees being blown into the dryer sections while the machine is making paper, sort of makes things hot too.

Bottom line is, it really worked good on our problem, which seems to be similar to yours.

The use of Peakvue always carries, IMO, a little leery feeling of making calls too early on bearings. It is a good tool, but calling for a replacement, IMO, should come 90% of the time from the velocity data from a routine condition monitoring setup on a paper machine. I never, in all my years, have made but a couple of calls from Peakvue data alone on outer race defects. The inner race calls are a little different animal when it comes to Peakvue, especially on slow speed bearings. As far as the FTF being present in Peakvue data, does not always mean the cage is bad.

Just my opinion and I could be totally wrong.

Thanks,
Ralph


Spot on with the Lube issues there. Our wet end rolls are manually greased (we don't have an auto system) to purge every 2 weeks. Not a pleasant job but has to be done. When this schedule is not adhered to we have come across bearing faults on both felt rolls and larger rolls so its very important this gets done. We have direct access to the bearing housings so that makes it easy for us and for the difficult to access ones we have put in remote lines to make it more safe.
ssimmon1

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Reply with quote  #47 
Quote:
Originally Posted by David Eason
Vibe-Rater,
My comment was meant as a lighthearted observation of the different cultures that we live in. Like SSimon, I was told in grade school that metric would replace imperial before I graduated school. That was 50+ years ago....

SSimon1,
If I am understanding your posts correctly, you are saying that you have a DCS set up for PeakVue 500 HP and an additional DCS set up for PeakVue 100-600 BP. That's good thinking. Bandpass filters can help provide clarity in your data sometimes, but you can't trust that you're seeing all of the energy. You have that covered with your highpass filter though, so you should be in good shape. You posted a PeakVue trend, and then later a trend from your normal vibe data. In both, we can see a long, flat stretch where life is good, then a short burst of activity. When seeing this trend on the wet end, I always pictured that burst of activity as crunching going on as contamination passed through the bearing raceway, and then the trend leveled back out as the bearing somehow spit out the mess. Our lube tech was allowed to disconnect the auto lube system and connect manually. He would open the purge and usually, he observed "gunk" come out as he added grease. I didn't see an outage in either of your trends, so you must have one coming up fairly soon. It would be good to know if there really is contamination in there. Changing the bearing will get rid of the bearing fault but it doesn't get rid of the cause. If it does have water in it, you'll have a chance to find out how it is getting in before it kills the next bearing.

David


Quote:
Originally Posted by Ralph Stewart
ssimmon1,

David has a good point on the purging of the bearing.

Where I worked for some 38 years, we developed a "ritual" of manually greasing all bearings which were on grease, on our two, 400 to 850 fpm machines, , immediately after the machine was shutdown on every 28 day cycle for routine maintenance and/or clothing change.

The oilers were on the job pumping grease, as soon as the machine stopped turning, until the grease and water was seen coming out of the bearings. Not only does "water" get in the bearing from being located in the wet area of the machine, but also from the condensate that develops as the machine cools down when shutdown. This condensate gradually enters into the bearings while it is in a cool down stage during each shutdown.

Some may say that filling the bearings with that much grease could cause a heat problem, but with the forced hot air of 200+ degrees being blown into the dryer sections while the machine is making paper, sort of makes things hot too.

Bottom line is, it really worked good on our problem, which seems to be similar to yours.

The use of Peakvue always carries, IMO, a little leery feeling of making calls too early on bearings. It is a good tool, but calling for a replacement, IMO, should come 90% of the time from the velocity data from a routine condition monitoring setup on a paper machine. I never, in all my years, have made but a couple of calls from Peakvue data alone on outer race defects. The inner race calls are a little different animal when it comes to Peakvue, especially on slow speed bearings. As far as the FTF being present in Peakvue data, does not always mean the cage is bad.

Just my opinion and I could be totally wrong.

Thanks,
Ralph


Both excellent pieces of advice! Thank you.


In regard to the bandpass and highpass PV readings, someone pointed out earlier that my order-based bandpass PV reading was in actuality a 500-1000Hz filter at speeds over 150 RPM...so I'm going to change both readings to Hz based readings so I know I'm covering the energy in that entire frequency range.

We have semi-annual scheduled outages. I've missed the window for getting anything on the schedule for this spring outage, so my next opportunity to get anything done will be in November.


Since the consensus is that some level of purging be done, I'll be entering a project to add tees, zirc fittings and check valves to the outlets of the automatic greaser manifolds so that we can manually grease each bearing without having to open any lines.


After pulling the 3 rolls we did based on some very low Peakvue readings...I concur that that call was likely WAYYY premature, but we knew that going into it. Now that we've observed what amount of damage that correlates to, we're now in a better position to know exactly how we expect these to trend going forward. It also shed some light on some potential installation/design issues, in addition to lubrication problems. I was extremely disappointed in the Valmet/SKF reports that I got on the bearings, so I'm going to send them out to our internal lab to confirm my suspicions.


Thanks for all the feedback. It's been much appreciated.

When I get the reports back from our lab, I plan to do a brief writeup on what the data was showing and what that translated to in the bearings.
Sinski

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Posts: 394
Reply with quote  #48 
Quote:
Originally Posted by ssimmon1




Both excellent pieces of advice! Thank you.


In regard to the bandpass and highpass PV readings, someone pointed out earlier that my order-based bandpass PV reading was in actuality a 500-1000Hz filter at speeds over 150 RPM...so I'm going to change both readings to Hz based readings so I know I'm covering the energy in that entire frequency range.

We have semi-annual scheduled outages. I've missed the window for getting anything on the schedule for this spring outage, so my next opportunity to get anything done will be in November.


Since the consensus is that some level of purging be done, I'll be entering a project to add tees, zirc fittings and check valves to the outlets of the automatic greaser manifolds so that we can manually grease each bearing without having to open any lines.


After pulling the 3 rolls we did based on some very low Peakvue readings...I concur that that call was likely WAYYY premature, but we knew that going into it. Now that we've observed what amount of damage that correlates to, we're now in a better position to know exactly how we expect these to trend going forward. It also shed some light on some potential installation/design issues, in addition to lubrication problems. I was extremely disappointed in the Valmet/SKF reports that I got on the bearings, so I'm going to send them out to our internal lab to confirm my suspicions.


Thanks for all the feedback. It's been much appreciated.

When I get the reports back from our lab, I plan to do a brief writeup on what the data was showing and what that translated to in the bearings.


Good way to go about it I think. Will be interesting to see how your reports come back. When you see them I think you will gain more confidence in future. 

Only 2 shuts a year? I am used to having 4 weekly maintenance shuts that are normally 12 hours in length and 1 major shut a year that is normally 3 days in length. We also have two caustic wash shuts a week that last about 1.5hrs. How long are the shuts when you actually have them?
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