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seanddd

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Reply with quote  #1 
Looking for some advice or information.  Does anyone have recommendations or experience with shock or vibration sensors that can be used for detecting shock or vibration levels while equipment is being transported from a rebuild facility to a mill facility?

Little background.  We have had several premature failures of large vacuum pump bearings mostly what has been deemed False Brinelling or fatigue...  These failures have occurred as little as a week after install and are usually within the first year of operation.  One theory or hypothesis is this damage may be occurring during shipping.  Traveling upwards of 500 miles on a flatbed semi on the great US interstates and highways.  It has been hit or miss with installing rubber pads under the pump feet during transport.  Any assistance would be greatly appreciated. 
John from PA

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Reply with quote  #2 
Back when I worked for BN, we tested the Pelican shipping containers that had been developed for one of our diagnostic instruments and found that the shock the instrument encountered in shipping by air was horrendous.  We initially used an electric logging device that as I recall went to 50 g’s and unfortunately it got pegged.  That enabled us to go back to Pelican who redesigned the interior with a more resilient foam interior.

I don‘t remember the device we used but a google search found devices by a company called Dry Pac that might be suitable for your purposes.  But some only show the highest level reached, not a log.  See http://www.drypak.com/shippingHandlingIndicators.html for the details.

If you need something along the lines of a data logger, see 
https://www.environmental-expert.com/products/electronic-shock-detector-for-shipment-monitoring-457032

M
ore to the story, should you have interest, I brought up this potential problem as I travelled to Reno NV for a visit to Minden, where BN is located.  As I was getting off the plane, I saw baggage handlers taking the Pelican case of what was likely our instrument, and literally tossing it 4 to 6 feet onto a conveyor.  That observation is what prompted the study.

Sorry about the underlining of text, this site does that to me sometimes when I use an iPad.
Curran919

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Reply with quote  #3 
As an alternative to data loggers, there exist chemo-mechanical alternatives that are designed explicitly for this (though with much less precision). They are just patches that you stick on your equipment or packaging.

DryPak is one such vendor.
John from PA

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Quote:
Originally Posted by Curran919
As an alternative to data loggers, there exist chemo-mechanical alternatives that are designed explicitly for this (though with much less precision). They are just patches that you stick on your equipment or packaging.

DryPak is one such vendor.


Must be an echo in this thread.  [wave]
electricpete

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Reply with quote  #5 
We have specified shock recorders in our motor repair specifications and they can be a pain.  Mainly because they require attention every time a motor gets delivered.   Are you going to require review of the recorder prior to accepting delivery? Who is responsible to do that?   Typically we let the repair vendor provide the shock recorder, which means we get a variety of different gizmo's showing up. An alternative would be to purchase our own recorder, but that requires some time too and coordination getting it to the repair shop. You have to select a limit (5g's true peak is mine).   If the limit is exceeded, do you have time to send the equipment back?  I'm sure someone somewhere has  a smooth process for this, but it has been somewhat of a pain for me. 

Shock recorders have a place, but it's certainly better to avoid bearing damage if you have any ways to help influence that.  Which leads to another angle on the problem: the preparation of the machine for shipment may have some relevance to the degree of bearing damage during a rough ride. 

For motor repair, a long established practice is to "block the shaft" prior to shipping. There is a belief that this helps the motor survive a rough ride with less potential for bearing damage.   Typically it involves putting axial pressure / tension and radial force on the shaft extension and locking it in position.   For example pull to put axial pressure on the shaft, pull it outwards outwards and then apply a clamp to the shaft which is also snug against the frame.  To put upward radial pressure on a horizontal shaft extension, wedge something between the shaft extension and the shipping base or pallet.  What does it really accomplish? Putting an axial load on the bearing takes some of the looseness out of that bearing (the fixed bearing or thrust bearing). The radial pressure if you're lucky might stop some movement on the non-fixed/non-thrust bearing although that seems more dubious when the non-fixed bearing is in the ODE as is most often the case.   I'm not sure how much it would help for your vacuum pump, but maybe worth considering.  People that repair vacuum pumps may have some idea about best practices to prepare them for shipping (sometimes people know how to do a job better, they just don't do it if it's not in the spec). 





Curran919

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Reply with quote  #6 
Quote:
Originally Posted by John from PA


Must be an echo in this thread.  [wave]


Wow, how embarassing...
Vibe-Rater

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Reply with quote  #7 
Hi Curran919, better twice than not at all. I don't always read the preceding posts in detail.  You see the thread header and start typing. Maybe that is bad form but when you are in a hurry. Sometimes that happens.  Stay safe and healthy wherever you are. rgds
Shoveldr

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Reply with quote  #8 
Quote:
Originally Posted by electricpete


For motor repair, a long established practice is to "block the shaft" prior to shipping. There is a belief that this helps the motor survive a rough ride with less potential for bearing damage.   Typically it involves putting axial pressure / tension and radial force on the shaft extension and locking it in position.   For example pull to put axial pressure on the shaft, pull it outwards outwards and then apply a clamp to the shaft which is also snug against the frame.  To put upward radial pressure on a horizontal shaft extension, wedge something between the shaft extension and the shipping base or pallet.  What does it really accomplish? Putting an axial load on the bearing takes some of the looseness out of that bearing (the fixed bearing or thrust bearing). The radial pressure if you're lucky might stop some movement on the non-fixed/non-thrust bearing although that seems more dubious when the non-fixed bearing is in the ODE as is most often the case.   I'm not sure how much it would help for your vacuum pump, but maybe worth considering.  People that repair vacuum pumps may have some idea about best practices to prepare them for shipping (sometimes people know how to do a job better, they just don't do it if it's not in the spec). 




This is what I have done in the past.  Another thing is to require vibration testing results at the factory and upon arrival on site, which may be more difficult with a vacuum pump.
Walt Strong

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Reply with quote  #9 
I think being proactive and eliminating travel vibrations with shaft blocking makes more sense than just monitoring vibrations; unless you really want to know. A vacuum pump is not a pallet of eggs!

Walt
Noknroll

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Reply with quote  #10 
Quote of the day

"A vacuum pump is not a pallet of eggs!" 😉

Thanks Walt, I'm going to try and put that into a conversation today 
electricpete

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Reply with quote  #11 

EPRI makes a lot of their documents available for free (or for the cost of giving up your email address).

Here is their document on shipping and storage of electric motors: https://www.epri.com/research/products/1009698

They don’t say much about blocking other than: “Ensure that the shaft is properly blocked to prevent axial and radial movement during transport. For methods, contact OEM (original equipment manufacturer), motor shop vendor or utilize specific site requirements.”

Below is a photo where they give for one example of blocking a vertical motor (Figure 2-5).  They build the yellow frame that and it pulls down on the shaft via bolt inserted into a threaded hole in the bottom end of the shaft.     Note that this only provides an axial /vertical force, but it seems pretty typical for vertical motors and sort of makes sense that this vertical direction is the most critical direction to block for a vertical motors.  Likewise, it seems for horizontal motors the radial /vertical direction would be the most critical to brace.  I have seen for horizontal motors on a pallet, either the the shaft extension is lashed downward to the pallet, or something is wedged between shaft extension and the pallet (frame is still lashed down to pallet).  I can't say I ever remember seeing blocking that preloaded both directions axial and radial as described in the text above.  If I had to guess I'd say blocking both directions is probably the cadillac for best protection, but blocking the vertical direction (axial for vert motors and radial/vertical for horizontal motors) seems to be what most shops do and might be good enough in most cases (for electric motors). 
VerticalMotorBlocking.gif 


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