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The supply chain disruptions of 2020 and 2021 have created a highly dynamic manufacturing environment, making asset availability for production a more important operations target than ever. Conducting an asset criticality assessment (ACA) identifies the 20 percent most essential assets in the plant, according to a range of production, safety, regulatory and other criteria, and helps focus maintenance and reliability activity accordingly. However, in today’s environment, expanding the ACA formula to consider “criticalness” benefits overall uptime, as well as the bottom line.
“Criticalness” involves a more nuanced approach than a traditional criticality assessment. It places a stronger emphasis on determining the machines your plant or company could not survive without and delves more extensively into the financial impact an asset has on an organization.
An ACA systematically ranks assets for workflow prioritization, maintenance strategy development, and other reliability initiatives. It provides the basis for determining the value and impact a specific asset has on operations. It also assesses the level of attention the asset requires regarding reliability strategy development (RSD) or asset management plans.
General benefits of an asset criticality analysis include:
Asset criticality and/or production criticalness thinking helps focus maintenance and reliability actions on vital assets and systems. Adding an Impact Rating of 1/3/9 for Safety, Environment, and Production brings further attention to risk elements.
An Asset Criticality Assessment a “decision-making tool” for evaluating how likely asset failures are as well as how they may impact organizational performance. The process of an ACA evaluates the value proposition of an asset from a risk perspective. It identifies the most critical assets according to their criticalness and unmasks operational risks.
Three essential points about asset criticality:
Even following these guidelines, many criticality assessments still deem more than half of a company’s assets to be critical. That exceeds the scope of an Asset Criticality Assessment but opens the door for an additional criticalness assessment.
Here are two tips for delving deeper into the “criticalness” of your machines and equipment:
“Criticalness” is defined as a state of urgency—an earnest and insistent necessity—that applies critical thinking to consider the larger environment’s needs and the operating context. It’s a more holistic approach in line with ISO 55000 and overall asset management needs.
Criticalness assesses assets and resources at a more macro level than pure asset criticality, helping teams formulate strategies for assets lying just outside the top 20 percent. Criticalness also follows an inherent reliability approach, where you consider the entire lifespan of the asset, not just how it is currently being used.
The weighted asset scoring methodology requires considering multiple criteria:
The evaluation starts by asking, “What is the asset’s effect on production output?” But it takes more than that into account.
The table in Figure 1 offers some guidelines for stack-ranking critical assets into tiers.
Failure has an immediate impact on or shutdown of multiple operations or systems. This failure will prevent capacity assurance due to operational, environmental, or quality issues. Equipment assigned this cursory criticality ranking (Rime Code) typically will have no redundancy and identified issues must be addressed immediately to complete scheduled production targets and goals.
Failure results in limited production capabilities, or shutdown of, a single operation or system. Equipment assigned this ranking may have redundancy or established bypass equipment or systems but may limit capacity assurance. Although this equipment could become highly critical if the redundancy or bypass fails, identified issues should be planned and scheduled with a higher work order priority. Safety systems designed for high reliability may also fall in this category.
Failure results in an impact on, or shutdown of, a single operation or system. Equipment assigned in this ranking typically has redundancy or established bypass equipment or systems to complete the production schedule.
Failure has no immediate impact on capacity assurance. Some of these assets may have the maintenance strategy of Run-to-Failure associated with them. In contrast, others require addressing issues promptly through the normal planned workflow processes.
Figure 1. Tier level definitions for asset criticality ranking
Create templates to guide the asset-ranking process, depending on the facility or environment, the task’s granularity, and the team’s experience level.
Figure 2 below is an example of a “mid-level” template.
Teams should select a template suited for their environment. For example, a highly granular template works best for a high-criticality environment, such as a pharmaceutical plant, but probably not for a distribution center.
“Take ownership of your criticality tools,” Perry says, and feel free to adjust templates to make them fit for purpose.
Figure 2. Sample Asset Criticality Analysis template
The asset criticality level combined with failure mode insights should determine the maintenance strategy approach, techniques, plan, and resource allocation. The 20 percent most critical equipment should receive comprehensive reliability maintenance, such as a complete failure mode analysis, automated sensors and alarms mapped to failure indicators, and regular screening inspections.
Figure 3 applies asset criticality tiers to the P-F Curve to show what comprehensive reliability maintenance looks like for critical assets. Only the far left (Tier 1) receives a full RCM (reliability-centered maintenance) but the first three tiers—the top 20 percent—qualify for failure mode mapping.
The assets after that receive “minimal maintenance” appropriate to their level of criticality and lifecycle stage. Minimal maintenance includes scheduled PMs and, for those assets moving closer to the right of the P-F Curve, may also include thermography screening if it’s important to know when an asset is likely to fail.