Machinery Lubrication

Machinery Lubrication Jan-Feb 2018

Machinery Lubrication magazine published by Noria Corporation

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A helicopter's planetary gearbox conveys power between the main drive shaft (from the engine) to the main rotor, giving the helicopter aerodynamic lift and thrust. e condition of the lubricant (the right health, cleanliness and supply) is essential for reliable, safe operation. Any failure of the lubricant can quickly start a disastrous chain of events, from lube failure to bearing failure to gear failure to rotor failure to lift failure to helicopter failure (crash and burn). While the helicopter example may be an extreme case, it is still an important and vivid illustration of the seriousness of early detec- tion and response. What might seem like a mild condition now (rising varnish potential, cloudy oil, elevated particle count, uptick in fuel dilution, out-of-grade viscosity, low oil level, etc.) can abruptly worsen to a runaway catastrophic outcome. Root Cause Alarms Proactive maintenance should always be "job one" in condition monitoring. To do well, it requires a solid understanding of root causes that are ranked by likelihood (the Pareto prin- ciple). ere is also a need to understand the criticality of each machine. What you perceive as "the cause" may be nothing more than a transitional step in a sequence of many in route to functional failure. e real root cause you are seeking is the one that could have been controlled or prevented. at is not to say your purpose is to look for someone to blame. I was once surveying a steel mill and noted that the needles on most of the pressure- differential gauges (used on filters) were in the yellow or red zones. My escort quickly commented that the maintenance staff no longer used the gauge readings to schedule oil changes. Instead, all oil filters were changed on six-month intervals regardless of the gauge reading. Needless to say, I was shocked. On-condition maintenance should always take precedence over scheduled maintenance. See the fault tree in Figure 1 used to trou- bleshoot the root cause of a large process pump failure. Asking the "repetitive why" takes you to the pump (and not the coupling or motor) that failed. Next, the pump bearings were found destroyed. An examination of the lubricant revealed heavy contamination. An effective functioning filter would have prevented such contamination. In fact, the filter was found to be plugged, as indicated by the red-alert pressure gauge reading that went unnoticed. Had an operator reported the high gauge reading and followed up with a filter change, the pump might have been saved. A red-alert gauge reading is not a pump failure unless it does not get reported with corrective action. If the filter became plugged prematurely, it should have been examined. Analyze the used filter to deter- mine the type and source of particles. How have they invaded the machine and the oil? Don't just change the filter. Correct the ingression points, i.e., the source of particles that plugs the filter. Many root causes can be detected by oil analysis. ese include various types of contam- inants, wrong oil and degraded oil. If cleanliness targets and other alerts are adjusted to promptly weed out root causes, they won't advance to even the earliest state of failure. I recently finished a case related to diesel engine failures. e lab was using a 5-percent alarm limit for fuel dilution. Anything less than 5 percent was reported as normal. No wonder the many defective fuel injectors were not detected until catastrophic engine failure had occurred. Coolant leak detection is also poorly deployed in diesel engine oil analysis. In my opinion, even the slightest amount of coolant leak is cause for concern. Weak Signal Alarms Long ago, researchers and tribologists discov- ered that the strength of signals being emitted during machine failure depends on the state of failure. Incipient failure produces weak signals, while precipitous (advanced) failure creates strong signals. is applies to various types of signals, including wear debris generation, vibra- tion, heat and acoustics. Hence, if you want to catch failure early, you need to be good at detecting and responding to weak signals. Sadly, many oil analysis programs are struc- tured to do the opposite. You can't fix a problem that you can't see. Rather than setting tight alarms and limits that are a slight offset from normal conditions, some programs don't alarm until problems advance to a state of imminent danger, such as two or even three standard devia- tions over the mean based on data history. Loose alarms equate to failure blindness. Some of the best oil analysis programs use cautionary alarms to alert condition-based main- tenance (CBM) technicians of abnormal lab data or a reportable inspection condition. is way, the alarm results in a more measured or throttled response. People who wrongly push the panic button often discredit the value of condition ML PUBLISHER Mike Ramsey - GROUP PUBLISHER Brett O'Kelley - EDITOR-IN-CHIEF Jason Sowards - SENIOR EDITOR Jim Fitch - TECHNICAL WRITERS Wes Cash - Alejandro Meza - Bennett Fitch - Loren Green - Michael Brown - Garrett Bapp - Devin Jarrett - CREATIVE DIRECTOR Ryan Kiker - GRAPHIC ARTISTS Patrick Clark - Josh Couch - Greg Rex - ADVERTISING SALES Tim Davidson - 800-597-5460, ext. 224 MEDIA PRODUCTION COORDINATOR Libby Bahlinger - CORRESPONDENCE You may address articles, case studies, special requests and other correspondence to: Editor-in-Chief MACHINERY LUBRICATION Noria Corporation 1328 E. 43rd Court • Tulsa, Oklahoma 74105 Phone: 918-749-1400 Fax: 918-746-0925 Email address: MACHINERY LUBRICATION Volume 18 - Issue 1 January-February 2018 ( USPS 021-695) is published bimonthly by Noria Corporation, 1328 E. 43rd Court, Tulsa, OK 74105-4124. Periodicals postage paid at Tulsa, OK and additional mailing offices. POSTMASTER: Send address changes and form 3579 to MACHINERY LUBRICATION, P.O. BOX 47702, Plymouth, MN 55447-0401. Canada Post International Publica - tions Mail Product (Canadian Distribution) Publications Mail Agreement #40612608. Send returns (Canada) to BleuChip International, P.O. Box 25542, London, Ontario, N6C 6B2. SUBSCRIBER SERVICES: The publisher reserves the right to accept or reject any subscription. Send subscription orders, change of address and all subscription-related correspondence to: Noria Corporation, P.O. Box 47702, Plymouth, MN 55447. 800-869-6882 or Fax: 866-658-6156. Copyright © 2018 Noria Corporation. Noria, Machinery Lubrication and associated logos are trademarks of Noria Corporation. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of Noria Corporation is prohibited. Machinery Lubri - cation is an independently produced publication of Noria Corporation. Noria Corporation reserves the right, with respect to submissions, to revise, republish and authorize its readers to use the tips and articles submitted for personal and commercial use. The opinions of those inter - viewed and those who write articles for this magazine are not necessarily shared by Noria Corporation. CONTENT NOTICE: The recommendations and information provided in Machinery Lubrication and its related information properties do not purport to address all of the safety concerns that may exist. It is the responsibility of the user to follow appropriate safety and health practices. Further, Noria does not make any representations, warranties, express or implied, regarding the accuracy, completeness or suitability of the information or recommen - dations provided herewith. Noria shall not be liable for any injuries, loss of profits, business, goodwill, data, interruption of business, nor for incidental or consequential merchantability or fitness of purpose, or damages related to the use of information or recommendations provided. Machinery Lubrication

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