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.
How an Asset Criticality Assessment works
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:
- Prioritizing the workflow and resources according to the most significant value to the overall organization
- Clarifying reliability maintenance strategies
- Ensuring that assets operate at their designed level of capacity
- Incorporating the safety implications of asset failure into the overall workplace safety plan
- Stack-ranking the order of continuous improvement projects
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:
- An ACA must identify the 20 percent most critical assets so that workflows, maintenance strategies, and resources can be allocated according to the organization’s most significant long-term risk.
- “Forced rankings”—those based more on objective, data-driven criteria rather than gut feeling or maintenance team bias—must be applied to make an Asset Criticality Assessment legitimate and impactful. In a world of limited resources, the forced ranking of an asset criticality approach prevents reactive decision-making from consuming all of a team’s time and energy.
- An asset’s criticalness cannot be determined by how an asset performs on a given day or month. Any ACA must apply more rigor and criteria than this.
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:
Tip No. 1: Rank all equipment by criticalness and classify by tier level
“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:
- Operational severity
- Safety severity
- Environmental severity
- Single point of failure (key inclusion)
- Maintainability
- Reliability
- Spares lead time
- Likelihood of failure
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.
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Tier 1 |
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. |
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Tier 2 |
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. |
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Tier 3 |
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. |
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Tier 4 |
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
Tip No. 2: Determine the top 20 percent and maintain them with more urgency
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.
Figure 3. How to lay asset criticality on top of the P-F Curve to align maintenance strategies
If an asset turns out to be flawed by design, build, or installation, the temptation is to make it a critical asset because of the investment made and the high risk of failure. But from a resource perspective, it likely makes more sense to apply “criticalness” thinking instead.
You may know the asset will continue to cause problems, and you want to avoid constant reactive maintenance—so it’s worth it to define a specific maintenance strategy for that asset. For example, if the asset is critical to production, consider installing a bypass. If it’s not essential for production, classify the asset as run-to-fail and plan to fail with minimal impact on the line, such as having a backup ready. Otherwise, the costs of preventing failure may exceed the actual costs incurred by the loss.
What ‘criticalness’ looks like in real plants
It’s easy enough to discuss Asset Criticality Assessment theory, but how do you apply tiered criticalness? Here are some examples. Figures 4a-b demonstrate the outcome of an ACA at Fluke Park, the Everett, Wash., headquarters of Fluke Corporation. This team initially categorized more assets than what 20 percent would allow as critical but emphasizing production criticalness helped focus the exercise.
Figure 4a Ranked critical asset list
Figure 4b. Preventive action test schedule and inspection routes
These criticality tools operate as living documents. Create and then review every 12-18 months to incorporate changes to assets, operations, and workflows.
Adding a “criticalness” filter to ACA efforts adds an analysis layer to the original assessment activity. By using definitions as well as a cumulative weighted score, plants can prioritize the risk categories most pertinent to their operations, from production to environmental, safety, and other consequence of failure. The best practices are those that return value to the organization and team.
