Your Equipment Criticality ‘right now’ is different to the Equipment Criticality ‘as new’ and to your Equipment Criticality ‘in future’

Equipment Criticality is a measure of Operating Risk and Business Risk. When operating risk or business risk changes so to does Equipment Criticality. When you do an Equipment Criticality Analysis the results only apply to the current situation and once circumstances change so to does the Equipment Criticality.



Dear Mike,

I have a question regards equipment criticality. We are busy developing maintenance strategies and as part of it we have to conduct a criticality analysis, i.e. to determine which assets will receive RCM attention, etc. and to provide directive for future work to be done on the equipment.

Two interpretations have come to the fore, i.e. what were the original critical items when the plant was commissioned and what are the current critical/risky items based on plant age, maintenance history, etc.

Both these views are developed from the risk = probability x total consequence formula, but the concern is that a current risky situation (developed for instance because of poor maintenance) might overshadow the initial equipment criticality.

In your experience, have you come across this interpretation and are there definitions to distinguish equipment criticality from the current equipment risk assessment and should there be such a distinction? Like to hear your views on this.



Hello Ryan,

Equipment Criticality is a measure for operating risk. As you say, risk = chance x total business consequence, and if consequence or chance change then the risk is changed.

Plant and equipment assets degrade with the effects of time, as well as through use and from abuse. An Equipment Criticality Analysis done for a plant in new condition and one done for the same plant in ten years time would most likely have different results.

Operating risk changes and so any Criticality review done in the past may not be applicable today. Your insightful recognition of Equipment Criticality ‘at new condition’ and Equipment Criticality ‘at current condition’ being different is a correct observation.

The plant and equipment health today is not the same as it was when it started operation; the business today is not in the same commercial world as it was in the beginning. Because things have changed for the business so too has its Equipment Criticality — today’s consequences and chances are unlikely to be the same as those of the past; nor for the future.

The complete risk equation = total consequence x [opportunity to fail x probability of failure when the opportunity arises]. It is not affected by time and if you put the current values into the risk equation you will get the current Criticality.

Ideally you should do a criticality calculation for plant assets every day and base today’s decisions on today’s criticality. But that is impossible without knowing the value of the variables that affect the consequences and chances for every asset.

For your client I would be concerned about today’s Criticality and what needs to be done to reduce today’s high risks. Once an asset’s risks are reduced the asset is no longer so critical and a new Criticality Analysis ought to be done to re-establish the new baseline position across the operation.

The real challenge for you is making the right maintenance strategy selection, and including the right maintenance activity content in work orders, to truly reduce risk. If you have made the right risk reduction choices your event consequence and/or chance will drop and your Criticality will fall with each risk elimination decision you make.

To see how worthwhile your risk reduction selections are for your client in reducing their operating risk, you ought to do a second Equipment Criticality to determine what risk remains after the maintenance strategies you selected for your client are actioned. I bet you that most of your maintenance strategy choices have but minor benefit in reducing the operating risk.

I hope that the above provides some useful ideas for you.


My best regards to you,

Mike Sondalini
Managing Director
Lifetime Reliability Solutions HQ


PS. If you require advice on industrial asset management, industrial equipment maintenance strategy, defect elimination and failure prevention or plant and equipment maintenance and reliability, please feel free to contact me by email at