Historically maintenance has focused on identifying equipment failure modes and correcting them. This is an ineffective asset management strategy because the failure modes always return and so you will always have to do maintenance.
A vastly more effective way to do plant and equipment maintenance is to apply a proactive plant wellness maintenance strategy
A great disservice has been done to all of us who work in industry. We have been taught to fix equipment problems and failures. We should have been taught how not to have equipment problems and failures.
Truly effective maintenance is proactive. It stops failure modes arising by preventing the causes of failure. Instead of fixing failing plant, the focus becomes plant wellness: ensuring life-long machinery health and well-being.
Sadly, the pervasive maintenance practice throughout industry is to find failure modes and then fix them. You wait for failure events to start and then correct the failure mode. This is ineffective, wasteful of resources and can never reduce equipment and machinery problems. It is an unhealthy practice—first get sick and then call-in the doctor to make you well. That is not the Plant Wellness Way. Plant Wellness is about creating machinery health and staying healthy for all your equipments’ service life.
There is a company that will sell you the PM work orders used in the nuclear industry, thinking that they are doing you a great favour in making them available. You can buy and use a wide range of preventive and predictive maintenance strategies that has taken the nuclear industry decades to develop and refine. When you look at the maintenance activities listed they are focused on finding failure modes and correcting them.
As an example, you are asked to look for over 140 pump failure causes on a centrifugal pump inspection. They provide a long checklist for the maintenance technician to work through. When they find a problem it is then fixed (you will always be growing new problems if your machine health strategy is to fix troubles only after they happen). It is a daunting task for any maintenance technician to tackle. It exposes them to misinterpretation because there are numerous failure causes for every failure mode. It is easy to mistakenly work on the wrong pump failure cause.
Fixing a machine after you detect a failure mode is an expensive equipment maintenance policy to follow. Such maintenance philosophy naturally produces high maintenance costs because you are repairing.
The Wrong Way to Prevent Roller Bearing Failures in Your Machines
is to Find a Failure Mode and then Replace the Bearing
We who work in asset maintenance have been taught to wait until a bearing failure mode reveals itself and then put in a new bearing. But only replacing the bearing leaves all the failure causes still in-place. If the bearing failure causes still exist within a machine its bearings must fail again in future.
Below is a list of over 120 roller bearing failure causes that produce the common bearing failure modes. (Follow this link to download 600+ Centrifugal Pump Failure Causes and their Failure Modes in an MS Excel spreadsheet from which the bearing failure list was extracted.)
With over 120 separate causes of roller bearing failures, many producing multiple failure modes, what chance do you think there is that all the failure causes will be found and removed if you wait for each failure mode to reveal themselves to you? If you wait for bearing failure to start before you address the cause you will always have plenty of bearing failures to repair.
For many years we have mistakenly been taught in Maintenance to correct failure modes. But fixing equipment failures cannot lead to the high equipment reliability we all seek.
The Plant Wellness Way to Extreme Roller Bearing Reliability
The Plant Wellness Way is not to let any equipment failure causes arise in the first place. You use your maintenance efforts to produce and sustain machinery health. In Plant Wellness Maintenance you create a lifetime of equipment health and thereby always get highly reliable plant and equipment. When you focus on keeping your machines healthy, and not on finding sick machines, you develop and sustain equipment health and thereby get the machinery uptime effect shown in the image below.
Maintaining roller bearings the Plant Wellness Way means doing those activities that prevent bearing failure. In the list above every bearing failure cause has a primary failure category that it belongs to. There are 14 bearing failure categories that cause all the roller bearing failure modes listed. In Plant Wellness you control and prevent the failure categories and as a consequence you remove all the failure causes.
The Plant Wellness Way requires use of precision maintenance to ensure that the machine and its parts’ are installed and kept to the lowest possible atomic stresses in its materials-of-construction. During operation the machine is run steady at design duty without cycling loads, pressures, flows or temperatures. Degradation reduction and degradation management is the operating creed.
Once installed correctly the machine, and all its working parts, including the bearings, are sustained for their entire life at the least material stress condition possible by controlling the failure categories. This involves ensuring lubricant is always chemically correct, that lubricant is contaminant-free, the parts’ fits are always in tolerance at operating temperature, that fasteners are at correct tension, along with applying all the other precision maintenance practices.
The companies that do maintenance and reliability best have taught their technicians to apply precision maintenance. They identify and remove the causes of machinery failure as part of the maintenance activity. By removing the root causes of a problem the technician improves machine reliability. Most maintenance technicians do not know how to do precision maintenance properly and would merely replace a failed part, thereby guaranteeing more machine failures in future.
Failure Mode based Maintenance vs.
Proactive Plant Wellness Maintenance
The reason Plant Wellness and its proactive precision maintenance works to lift equipment reliability to extreme levels, is that its practices stop multiple failure causes. Where failure mode based maintenance tackles a failure cause one at a time (and never removes them all), Plant Wellness proactive maintenance addresses all failure categories together. You set-up your machines so that you keep their parts in an optimal health environment. Plant Wellness guarantees outstanding equipment reliability because the causes of failure are always prevented from turning into failures.
A plant wellness philosophy promotes machine health and well-being, whereas a failure mode correction mentality expects ill-health and sickness. That difference in mindset determines whether you can become world class in maintenance and reliability, or whether your plant and equipment will always have failures and breakdowns.
My best regards to you,
Mike Sondalini
Managing Director
Lifetime Reliability Solutions HQ