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Sr. Member
Posts: 78
Reply with quote  #1 
My guys were changing out a closed loop cooling water pump (Flowserve/Durco 2K6x4) and I happened to wander by and took a look at the coupling. There is a fine dust in the Woods coupling half's that due to its color I assume is from the coupling insert. I took a real good look at the insert but didn't see any signs of wear. Could this be a normal condition after many years of service? We have 10 of these pumps and was wondering if it was time to think about changing out the inserts.     

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Sr. Member
Posts: 106
Reply with quote  #2 
I think you have two choices:

first: Predictive maintenance (It´s time for a good vibration revision). If you know a good vibration study company I would prefer, with ten pumps, to do a vibration study in the 10 pumps, so comparatively a good analyst will be able to say you what couplings change or no (or other parts). There are defined  vibration patterns to identify this problem without having to remove all the pumps and subsequently realign [frown].

Second: preventive maintenance:
- Remove all the electrical motors
- change all the couplings
- Perhaps preventively change any bearing
- Assemble
- Align.

Quantify the difference in time and money (production losses + spare parts costs + manpower costs) of the two choices. And remember "if it's not broken, do not fix it"
Danny Harvey

Sr. Member / Moderator / Supporter
Posts: 1,403
Reply with quote  #3 
How long have the sleeves been in place? How about the hubs?  It looks like they may be worn which would cause wear in a new sleeve.

This material is very torsional rigid and if your service factor is too high, it starts and stops often or reverses, this may not be the best selection.

Check the motor hp and speed or torque against the coupling rating with the Hytrel sleeve.  If the service factor is over about 4 or 5, that can lead to premature wear and even rapid failure.

Sr. Member
Posts: 670
Reply with quote  #4 
Originally Posted by ruben
"if it's not broken, do not fix it"

Best advice ever

Sr. Member
Posts: 384
Reply with quote  #5 
If my coupler element looks like that after many years of service I would flip it 180° reinstall it and go have a beer. If I was really feeling like overachieving that day I would replace the element and then go have several beers. That looks like normal wear for years of service. If it looked like that in weeks or a couple months I would look into it. You have to figure even a properly aligned pump (.001"-.004") is going to cycle the teeth on those elements against the coupler half 120 times a second for a 3600 RPM pump (is RPM an acceptable unit to use here these days?).

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Posts: 843
Reply with quote  #6 
Big J 
I like your strategy,
Hz, orders cpm rpm its all the same [wink]

Sr. Member
Posts: 78
Reply with quote  #7 
I looked at the vibration data from both our installed sensors and the walk around data and don't see anything that might lead me to an alignment or coupling issue. The pump was replaced due to a seal leak (not bad enough to change IMHO) but due to the age-almost 18 years I will stipulate that the coupling be changed if we work the other machines.
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