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Criticality Analysis

Criticality and Risk

What is criticality?

Criticality, in its simplest form is a measure of how important something is related to some evaluation category  and the overall mission or goal.  A simple example to illustrate this would be to consider a facility comprised of hundreds of pieces of equipment.  The facility has a mission, or a goal, that each asset is to contribute towards.  How important are each, or any, of those pieces to that mission?  The answer to that question depends on what category you are looking at, (up-time, safety, cost of operation, capital spend) and its impact on the mission.

In relation to up-time, for example, there might be several key pieces of process related equipment that can shut the whole facility down, or at least seriously reduce capacity.  Those units would obviously be considered critical if the goal is to maximize up-time.  Conversely, if the evaluation is for safety or environmental compliance, the equipment list might look quite different, what is now considered critical, to assure safety and environmental objectives are met, and what might pose a serious risk to meeting those objectives in the event of a loss of some equipment functionality.

So how do we accurately, consistently, and comprehensively identify what is critical?  To get there we need to zero in on what is ‘criticality’, specifically, and then see how best to identify it in a real world context.

At the core, criticality is related to risk: both bad and good. Risk of negative or damaging consequences when considering the “bad”; and potentially beneficial effects when considering the “good”.  For this discussion, we will use the negative  perspective, as it is those risks we clearly want to eliminate.

Risk in complex systems(even those having multiple locations, areas, or types of risk events) is commonly represented by a risk matrix as in Figure 1.  In this form of presentation a two dimensional grid is used: with probability of occurrence of the ‘event’ on on one axis, and the consequences of an ‘event’ other axis.  Herein, an ‘event’ can be anything we define as undesirable in our discussion, such as a particular  type of failure, or unintended occurrence.

Figure 1 Risk Matrix

Either a higher likelihood of occurrence or a worse consequences places the event at a higher overall risk, represented be the upper right quadrant of the grid shown in red.  Different types of events are plotted as points representing their respective consequences and probability of occurrence, producing a risk matrix.  This type of presentation is useful to sort out the “biggies” from the “no worries” events as far as general groupings.

A criticality analysis is used to evaluate potential events against one another.  Its goal is to determine the proper position for the event within the grid, more or less probability, more or less consequence resulting in commensurate shift of position.  But for it to be broadly applicable the analysis must use a consistent process comparing each event, both in the present or current evaluation, as well as in any future evaluations.  Such that, will the position of A relative to B be accurately determined at some future evaluation?

An effective criticality analysis process should provide not only a general quadrant grouping, but should be able to produce a ranked listing of analyzed potential events in order of risk.  This ordering is what is commonly known as criticality.  It is simply the ranked order of events within a system.  Of special note, it is not necessary to base the ranking on an objective “score” for risk based on a specific scale, although that may be included.  As is mostly the case, an absolute scale is untenable an impractical when comparing large process systems in most facilities.  Data does not exist for all types of pumps, in all conditions, for all types of service.  Quite simply, each system is unique.  Rather, the key requirement for broad applicability, and meaningful comparisons between facilities as well as over time, is that the means of evaluation remain consistent.

In a risk matrix such as the one shown in this article, relative criticality values for each event (point) can be represented by the length of a line connecting the point to the axis intersection point (0,0).  For example, the length of the dotted line for point B is longer than the dotted line for point A; meaning point B has higher criticality.  For this example relative criticality is fairly obvious even without the lines, relationships between points can be more complex, or at least not apparently obvious.  Using visual acuity alone, it would be difficult to order all of the points shown in even the simple diagram shown here.

Further, the above example illustrates the simple challenge of ranking of events against one criteria, be it up-time or safety.  The evaluation becomes increasingly complex with each additional criteria (or dimension) such as safety, environmental, commercial, contractual, cost of operation, cost of capital, maintenance cost, public perception, stakeholders, etc., particularly when evaluating events concurrently.

The criticality analysis methodology that Uberlytics supports is a Multi-Dimensional Composited-Multiple-Scenario method (MDCMS).  The methodology was developed by Terry Nelson, who is chief technical consultant to Uberlytics, and forms part of the solution team consulting in respect to the approach at all levels.  The approach is most effectively used in a facilitated workshop environment where a trained facilitator, proficient in the criticality analysis process leads, a team of key and knowledgeable stakeholders through the analysis, documenting the team’s work as they proceed.

Criticality Analyzer™ empowers you the client to evaluate, discover, and act.  It is a stand alone PC based (Windows, Mac, Linux) software tool specifically designed to support this facilitated team approach and the MDCMS method.  It captures the data, presents it in multiple graphical  and tabular forms,  and provides the user/client the greatest flexibility to act on the results.  The long term benefit is that it places the power to re-evaluate previously analyses systems, or to do subsequent first-time evaluations on facilities not yet analyzed, into the hands of you: the client/facility owner.

Find out more about Criticality Analyzer™ or how to get Criticality Analyzer.

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