Criticality is a measure of the relative importance of something to an organization's mission or objectives. I prefer using critical and importance synonymously. Merriam-Webster says it stronger by defining critical as being indispensable or vital.
In systems engineering and reliability engineering, we address systems or subsystems of higher importance to an organization with fault prevention measures. Fault prevention falls into two classes: fault avoidance (usually in the form of de-rating stresses or higher performance criteria) or fault tolerance (usually in the form of redundancy).
One common misconception is to equate criticality and risk. Risk is defined as the effect of uncertainty on objectives. A layman's definition is risk in the deviation from expectations. Risk is situationally specific and can be evaluated differently at an organization's corporate, operations, or business unit levels. Risk can also be expressed in over two dozen ways, including the multiplicative product of the consequences and likelihood of failure. Criticality is the more general case (importance to organization mission and objectives), and risk applies more granularly (expressed at different levels and on different components within the overall mission and objectives).
Another common misconception is that the likelihood of failure or condition of something makes it more critical. If something is not important (indispensable, vital) to the mission and objectives of the organization, then its condition does not increase its relative importance. In fact, there is a good case for either running it to failure or removing it as unnecessary (studies have shown up to 15 percent of system components are superfluous). The likelihood of failure may impact our evaluation of risk or our improvements plans, but the likelihood of failure will not make a system more or less critical.
A third misconception is that the presence of fault avoidance (usually in the form of redundancy) makes something less critical. This is the false equivalent of saying your respiratory system is not as important as your circulatory system because you have two lungs and only one heart. Indeed, they are equally important because you cannot live without both systems. In practice, we incorporate fault avoidance into our most critical systems (i.e., you have redundancy because the system is critical).
Criticality analysis is the best way to prioritize organizational activities such as business process improvements, condition assessments, preventative maintenance program improvement, workforce development, work prioritization, inventory management & critical spares, predictive maintenance programs, health & safety improvements, design or re-designs, O&M budget development, CIP prioritization, and communications. Improving system performance starts with criticality analysis.
JD Solomon Inc provides criticality analysis for many applications pertaining to facilities, infrastructure, and the environment. Contact us for more information on systems thinking and approaches as well as the Solomon-Oldach Asset Prioritization (SOAP) method.