Electricity + Control September 2017

PLANT MAINTENANCE, TEST + MEASUREMENT

So, What is Still Wrong With Maintenance? Mike Sondalini, LRS Consultants Global

The role of maintenance is to eliminate operating equipment risks. Yet, organisations using Preventive and Predictive Maintenance strategies still have equipment breakdowns.

Take Note!

A part’s chance of failure changeswith its stresses. Less stress slows the degradation rate and the part lives longer. Higher stress lifts the degradation rate, and the part’s life shortens.

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T hey have forced outages and stoppages. They consistently get emergency repairs. So, what makes today’s Maintenance paradigm so unsuccessful at equipment risk elimination? Why maintenance can never stop plant and equipment failures Every part in every machine has a degradation curve. The length and slope of the degradation curve depends on a component’s engineering de- sign and how it is cared for during its lifetime. When parts are new they provide their best service. As a part degrades its performance drops. Curves are monitored and tracked using appropri- ate condition monitoring methods. The ‘P’ (Poten-

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tial Failure) point is the earliest that we can detect changed performance. This allows the remaining service life to be predicted so the part can be re- placed or refurbished as planned maintenance before it is unusable at the ‘F’ (Functional Failure) point. Breakdowns, forced stoppages, and emer- gency work happen to equipment, despite using the best preventive and predictive maintenance strategies. Their parts’ degradation curves get dramatically cut-short. A part’s degradation curve shortens and falls as its material-of-construction is damaged by stress. Those unintended equipment failure events – breakdowns, emergency repairs, forced stoppages – result from excessive stress- es in microstructures curtailing the part’s degrada-

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SEPTEMBER 2017