Justifying Condition Monitoring
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Return to Condition Monitoring - Predictive Maintenance Techniques
Justifying Existing CM Activities
It is a common experience that when organizations stop condition monitoring
- For equipment that does not have full redundancy, there are failures within a year or so that affect business operation.
- For equipment with full redundancy, there are multiple failures in systems within 3 or 4 years that affect business operation.
The failure pattern for most mechanical equipment such as pumps, fans, motors and gearboxes is ‘high early failures’ going to a background random failure rate. Because of this the biggest payback for CM is for monitoring equipment directly after repair or overhaul. This is using CM as quality control for maintenance and is typically easy to justify will all except low cost non-critical equipment.
The normal way to justify continuing to do condition monitoring is to review all the faults recorded in the CM reports and estimate the cost savings in repairs, operations and safety. You need to give a cost operations and safety problems. These cost savings are then compared to the cost of performing the monitoring activities. If the monitoring cost is less than the total cost savings then the monitoring is viable. This type of analysis is not always easy to do formally but it is usually not too hard to get a gut feeling if the monitoring is viable or not.
Where the condition monitoring does not seem viable there are some things to look at
- Are the condition monitoring report recommendations being effectively implemented in the recommended time.
- Are the condition monitoring techniques being used appropriate for the equipment and correctly implemented by capable personnel.
- Are there less costly condition monitoring techniques available that will still be effective eg in-house using simple instruments rather than using contractors
- Are the routine monitoring frequencies appropriate for the equipment criticality, failure rate and PF intervals (warning time)
Some people faviour use of time based maintenance rather than Condition Based. See first figure below from Ron Moore presentation that shows the reduced maintenance cost with greater use of vibration monitoring. Oil analysis shows a similar result. The second figure shows the effect of time based maintenance, which there is a certain amount of low cost PM such as lubrication but time based equipment change outs are very expensive. There is some other good information in the presentation.
The other thing that needs to be considered is where Condition Monitoring fits in your overall reliability strategy.
