Explanation of Series System Reliability Property 3 for Plant and Equipment Reliability Improvement

Series System Reliability Property 3: A small rise in the reliability of all items causes a much larger proportionate rise in system reliability.

It tells us that for a small change in reliability at equipment level we can get a massive rise from that effect at business level.

An explanation of


Slide 35 – Use Series System Reliability Property 3 When You Want to Get Maximum Profits from Plant and Equipment Reliability



Series System Reliability Property 3 is amazing. The numbers in the boxes in the top reliability block diagrams on the slide tell an exciting story. They show us that changing each equipment’s reliability from 0.93 up to 0.95 is a 2.1% improvement, yet the total system-wide improvement produced is 8.9%. That is more than four units of improvement for each unit of effort—a 400% return-on-investment.

The numbers don’t lie. The system reliability formula tells us what will happen when we make a change that affects the entire system as one.

When we repeat the exercise for the reliability block diagrams at the bottom of the slide it confirms the effect. In this case our process train contains four equipment items. For a 2.1% rise in individual equipment reliability we get a positive 8.9% impact on the business. It seems that as the reliability of more equipment in the production train is improved the business gets ever greater benefits.

Using Series System Reliability Property 3

So, what are these system-wide improvements that Series System Reliability Property 3 tell us can produce massive returns-on-investment?

The improvements that fit Series System Reliability Property 3 have certain characteristics. One is that by doing them the reliability of each equipment item on which they are applied rises. A second characteristic is that they are universally applicable and can be used repeatedly in the same situations.

Examples include, Lubrication Management, Precision Maintenance, Operator up-skilling and training on their equipment. Maintainer up-skilling and training on their equipment, and the use of Standard Operating Procedures.

A third characteristic is that they are best practices. When best practices are used on equipment, and when working on equipment, they deliver higher reliability every time they are used. In Plant Wellness Way EAM we make use of Series System Reliability Property 3 everywhere there is a series system arrangement of any sort, be it production equipment or work processes.


This slide is a companion to the new Industrial and Manufacturing Wellness book. The book has extensive information, all the necessary templates, and useful examples of how to design and build your own Plant Wellness Way enterprise asset life cycle management system-of-reliability. Get the book from its publisher, Industrial Press, and Amazon Books.

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