An asset criticality assessment (ACA) is most impactful when assets are ranked by “criticalness” rather than criticality. “Criticalness” is a deeper, more nuanced approach than how many criticality assessments are done today. It places a stronger emphasis on determining the machines your plant or company could not survive without.

The difference between “criticalness” and “criticality” was the theme of a December 2020 webinar—“Why you must rank your assets for ‘criticalness'”—presented by Fluke Reliability experts Gregory Perry and Frederic Baudart.

They outlined a strategy for improving your ACA by delving more extensively into the financial impact an asset has on an organization. We discuss this strategy and offer a template below, but you should view the webinar for more detail.

Three other essential points surfaced during this presentation:

  • An ACA must identify the 20% most critical assets so that workflows, maintenance strategies, and resources can be allocated according to the organization’s most significant long-term risk. In many criticality assessments today, more than half of a company’s assets are deemed critical, but that is not realistic. Know your 20% most critical assets.
  • “Forced rankings”—those based more on objective, data-driven criteria rather than gut feeling or maintenance team bias—must be applied to make an ACA 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, Perry notes.
  • 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.

Back to basics: How an ACA 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
  • Stack-ranking the order of continuous improvement projects

Perry calls an asset criticality analysis a “decision-making tool” for evaluating how asset failures 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.

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

Perry defines “criticalness” 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%. 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 in an ACA requires considering multiple criteria. These experts say:

    • Operational severity
    • Safety severity
    • Environmental severity
    • Single point of failure (key inclusion)
    • Maintainability
    • Reliability
    • Spares lead time

The evaluation starts by asking, “What is the asset’s effect on production output?” But it takes far more than that into account.

The table in Figure 1 offers some guidelines from Perry and Baudart for stack-ranking critical assets into tiers.

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.
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.
Tier 3 Failure results in an impact on, or shutdown of, a single operation or system. Equipment assigned this ranking typically has redundancy or established bypass equipment or systems to complete the production schedule.
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

Perry recommends several ACA templates to guide the asset-ranking process, depending on the facility or environment, the task’s granularity, and the team’s experience level. Watch the webinar for more information.

Figure 2 below is an example of a “mid-level” template.

Teams should select an ACA 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

Figure 2. Sample Asset Criticality Analysis template

 

Tip No. 2: Determine the top 20% 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% 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%—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

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, says Perry, 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

In the second half of the webinar, Baudart walks through three different asset criticality scenarios he has experienced.

“It’s easy enough to discuss the theory, but how do you apply ACA in reality?” he challenges. “It makes a lot more sense when you see it for real.”

Figures 4a-b demonstrates the outcome of an ACA at Fluke Park, the Everett, Wash., headquarters of Fluke Corporation.

“This is a living document,” Baudart says. “You do it initially and then review it every 12-18 months to see what’s changed with your assets, operations, and workflows. It’s not something you want to do once and leave.”

Figure 4a Ranked critical asset list

Figure 4a Ranked critical asset list

Figure 4b. Preventive action test schedule and inspection routes

Figure 4b. Preventive action test schedule and inspection routes

Additional plant examples included a food manufacturer in the Midwestern United States with various gearbox, conveyor, pump, and valve assets; and a wastewater treatment plant on the U.S. West Coast with critical pumps, separators, motors, and digester systems.

Listen to the webinar online to learn more about the “criticalness” approach and hear all three case studies.

 

Related articles:

Webinar: Using the P-F curve to plan maintenance