Criticality analysis, what is it and how is it managed

Criticality analysis is a maintenance approach used to prioritize resources based on potential risks. Here’s how it’s managed

In order for a maintenance plan to be truly effective, it’s important to identify risks and how certain equipment can fail. It’s also important to evaluate which systems need to be repaired and prepare the various interventions by priority.

But how can we determine which resources are actually more “critical” within a production system? In most common cases, this is done by implementing a “Criticalilty Analysis”. It’s a widely used methodological approach within the Facility Management discipline. Its purpose is to classify a company’s assets according to the effects their potential failure could have on the organization’s processes and overall productivity.

If you haven’t heard about this type of analysis, find out more and discover methods and tools necessary to perform it correctly in this article.

Before moving on to develop criticality analysis in maintenance, why not get your hands on a Facility Management software. It’s a centralized, cloud-based system that allows you to keep track of all resources and activity within your facility. A platform that provides a reliable database within which you can set up any type of assessment.

What is Criticality Analysis?

Criticality analysis is a structured and systematic method used in the maintenance sector. It’s used to classify assets based on the operational risks associated with probable failure of equipment.

As the name suggests, the purpose of this analysis is to measure the priority of some assets over others. Each one is assigned a different “criticality” level, essential to establish an order of priority in planning of maintenance interventions.

Why is Criticality Analysis so important?

The implementation of criticality analysis plays a fundamental role in almost all types of maintenance. It helps identify and document all possible conditions that can lead to a company’s assets to fail. It’s also a way of evaluating consequences that such failures may have on the safety, operability and functioning of a production system as a whole.

Systematic assessments of criticality increase the possibility of achieving the company’s objectives. It allows you to address reliability aspects and availability of equipment based on real risks rather than simple individual perception.

Once an asset is classified according to its criticality, it is then possible to prioritize workflows and schedule preventive or corrective actions on time. Targeted maintenance strategies are therefore implemented reducing the risks associated with potential failures related to each individual resource.

Criticality analysis: Prioritizing Workflows

How is a criticality analysis carried out?

The methods used to perform the criticality analysis in maintenance are two, one of which is in-depth and the other simplified. Both approaches allow you to define a numerical value called RPN (Risk Priority Number) that helps classify the criticality level of each asset.

Before proceeding with the criticality analysis it is important to perform some fundamental steps that have the purpose of:

identify the resources to be included in the evaluation, by compiling a list which should normally not exceed 20% of the total resources;
create a team qualified experts to investigate the assets of the facility;
assess the risks associated with the potential failure events of each individual asset.

Once you have developed these steps, it is possible to go forward with the in-depth method and evaluate the RPN index applying the formula below. This formula takes into account the probability of a failure occurring, how severe the effects are on the production and the possibility of detecting the issue:

RPN = Severity x Probability x Detection

For the determination of these parameters it is possible to set reference scales. To describe the frequency with which a fault occurs we could use, for example, the following scale of values:

PROBABILITY
5	Frequent (once a month or more)
4	Probable (once a year)
3	Occasional (once every two years)
2	Remote (once every ten years)
1	Very unlikely (once every fifty years)

The severity categories focus on different aspects related to the impact that a potential failure could have on health, safety, the environment, operations and so on. The evaluation table can have the following structure (the choice of severity level will be based on the highest impact identified):

Minimal

SEVERITY
	SAFETY	ENVIRONMENT	OPERATIONS	COSTS
4	Deaths or Serious Injuries	Serious impact on the environment	Production line interruption	Between €200,000 and €500,000
3	Serious injuries or illnesses	Significant impact on the environment	Extremely low production capacity	Between €50,000 and €200,000
2	Minor injuries or illnesses	Mild impact on the environment	Limited production capacity	Between €10,000 and €50,000
1	No injuries	Low impact on the environment	disruption to productivity	Less than €10,000

Detection categories, on the other hand, refer to the ability to detect a fail using currently available tools and controls. A possible classification for this type of parameter could be the following:

DETECTION
5	Very low probability that a fail or defect will be detected with existing checks and instruments
4	Low probability that a fail or defect will be detected with existing checks and instruments
3	Moderate probability that a fail or defect will be detected with existing checks and instruments
2	High probability that a fail or defect will be detected with existing tests and tools
1	Very high probability that a fail or defect will be detected with existing checks and instruments

Once the values have been obtained from each table, it is possible to calculate the RPN for the asset using the formula above. Additionally the relative risk category can be classified on the basis of a reference scale similar to the following:

RISK CATEGORY	RPN
Extreme risk	100-200
High risk	70-99
Medium risk	90-69
Low risk	15-29
Risk not appreciable	0-14

The simplified approach for assessing criticality ignores detection requirements (which are sometimes too confusing and difficult to apply) and uses only severity and probability rates. This method involves the construction of a criticality matrix. The latter is a grid in which the severity of a failure event (shown on the X axis) is plotted versus the probability of such an event occurring (shown on the Y axis), as follows:

P R O B A B I L I T Y	6	12	18	24	30	36
	5	10	15	20	25	30
	4	8	12	16	20	24
	3	6	9	12	15	18
	2	4	6	8	10	12
	1	2	3	4	5	6
	SEVERITY

The intersection between the two parameters (severity and probability) provides the RPN index which can be used to determine the risk category of the asset.

4 Ways a Criticality Analysis can help your business

Criticality analysis is often considered as a crucial part of managing a facility’s resources and processes because it provides numerous benefits, including:

focus maintenance efforts on items that count more and less time spent on activities that do not reduce the risks for the assets;
better planning of activities in Total Productive Maintenance (TPM) or preventive maintenance processes. This is obtained by assigning a higher priority to the operations and interventions that need to be developed first;
better risk management, thanks to the identification of potential failure events and the most damaging consequences for a production system. This helps to choose the best strategy to be undertaken;
the rationalization of the costs of managing the structure, with a reduction in expenses relating to unnecessary activities and an appreciable reduction in costs due to unplanned downtime.

How can a CMMS system help in criticality analysis?

Criticality analysis in maintenance is based on the collection of reliable and accurate data. These are related to the equipment operating conditions. You can understand how it’s increasingly essential to use a good CMMS (Computerized Maintenance Management System).

Software designed specifically to manage maintenance activities allows, in fact, to:

track any resource or activity within a facility;
monitor asset performance in real time;
tracking failure rates (MTBF, MTTF, MTTR);
produce detailed reports that help plan maintenance activities.

Discover how easy it is to implement a criticality analysis with the help of a Facility Management software, the only system that allows you to manage all aspects of maintenance from a single centralized platform completely in the cloud. This will provides you with the information you need to assess the levels of risk and criticality of your assets.