Criticality Analysis: Definition, Methods and How to Perform It

What Is Criticality Analysis?

Criticality analysis is a systematic process to identify which assets, systems, or processes have the greatest impact on operations if they fail. It ranks equipment and infrastructure by how much their downtime costs the business in lost revenue, safety risk, or operational disruption.

The purpose is simple: focus maintenance effort and resources on what matters most. You cannot maintain everything equally, so criticality analysis tells you where to spend time and money to get the greatest benefit.

Why Criticality Analysis Matters

Manufacturing and industrial operations contain hundreds or thousands of assets. Maintaining all of them equally is impossible and wasteful. A small hydraulic pump on a support system is less critical than the main production line pump. Criticality analysis forces you to distinguish between them.

With criticality analysis, you can:

• Prevent the most damaging failures by focusing maintenance where it matters
• Allocate resources efficiently and justify spending on high-risk assets
• Reduce downtime and protect revenue
• Plan capital investments in equipment replacement or redundancy
• Improve safety by identifying assets critical to worker protection
• Build maintenance schedules based on real operational impact, not guesswork

How Criticality Analysis Works

Criticality analysis typically follows these steps:

1. Identify All Assets: Create a complete inventory of equipment and systems in your facility.
2. Define Failure Modes: For each asset, identify what can go wrong (bearing failure, loss of seal, electrical fault, etc.).
3. Assess Failure Impact: For each failure mode, estimate the consequence: lost production, safety risk, environmental impact, or repair cost.
4. Assess Failure Likelihood: Consider equipment age, history of failures, operating conditions, and current condition. Use Mean Time Between Failure (MTBF) if available.
5. Score and Rank: Combine impact and likelihood to create a criticality score. High impact and high likelihood = highest priority.
6. Recommend Actions: High-criticality assets get aggressive maintenance (Preventive Maintenance or Predictive Maintenance). Lower-criticality assets may run to failure.
7. Document and Review: Record findings and revisit annually as assets age or operations change.

Key Factors in Criticality Analysis

Failure Consequence (Impact)

What happens if the asset fails?

• Production Loss: Does the entire line stop, or can production continue on other equipment? How much revenue is lost per hour?
• Safety: Does failure create a hazard to workers or the public? Safety-critical assets are high priority regardless of other factors.
• Quality: Does failure compromise product quality or cause scrap?
• Repair Cost: How expensive is the replacement or repair? Specialty items with long lead times are riskier.
• Cascading Effects: Does failure of this asset trigger failures in dependent systems?

Failure Likelihood (Probability)

How likely is the asset to fail?

• Age: Older equipment generally has higher failure rates, especially past design life.
• Operating Conditions: Equipment running at high temperatures, pressure, or duty cycle fails faster.
• Historical Data: If an asset has failed frequently in the past, it is likely to fail again unless the root cause is fixed.
• Mean Time Between Failure (MTBF): Manufacturer specifications or historical averages give baseline failure rate.
• Current Condition: Equipment showing signs of wear, vibration, or temperature rise is closer to failure.

Failure Detectability

Can we spot problems before failure occurs?

• Visible Degradation: Some failures give warning signs (noise, leaks, vibration). These are easier to catch with Condition Monitoring.
• Sudden Failure: Some assets fail without warning. These need more aggressive preventive maintenance or redundancy.
• Monitoring Feasibility: Can you install sensors to track health? Complex equipment in hazardous environments may be hard to monitor.

Common Criticality Analysis Methods

Risk Priority Number (RPN)

A simple scoring method used in Failure Mode and Effects Analysis (FMEA):

RPN = Severity x Occurrence x Detection

Score each factor from 1 to 10, then multiply. Higher RPN means higher priority. Simple to use and understand.

Risk Matrix

Plot assets on a 2x2 or 3x3 matrix with likelihood on one axis and consequence on the other.

• High likelihood, high consequence: Critical; needs aggressive prevention
• High consequence, low likelihood: Important; monitor closely
• Low consequence, high likelihood: Annoying but not critical; standard maintenance
• Low consequence, low likelihood: Non-critical; run to failure is acceptable

Criticality Index

A weighted scoring system that considers multiple factors:

Criticality = (Impact Score x Likelihood Score) + Safety Factor + Environmental Factor

Allows customization based on your operational priorities.

Failure Mode, Effects, and Criticality Analysis (FMECA)

An expanded version of FMEA that includes criticality scoring. Documents all failure modes for each asset, estimates likelihood and consequence for each, and ranks them. More rigorous than RPN but also more time-consuming.

Using Criticality Analysis Results

Practical Example: Food Processing Facility

A food processing plant performs criticality analysis on its equipment:

• Main production line conveyor (high criticality): If it fails, production stops. 100 units per minute x cost per unit = $5,000 per hour downtime. Gets Predictive Maintenance with vibration monitoring. Critical spares kept in stock.
• Backup conveyor (medium criticality): Stops line if main is down, but main rarely fails. Gets Preventive Maintenance quarterly. Spares ordered as needed.
• Forklift (low criticality): If one breaks, use another. Gets basic maintenance. Failures are tolerable.
• Emergency cooling pump (high criticality): Failure creates food safety risk and compliance violation. Gets rigorous Preventive Maintenance. Redundant backup pump installed.

Best Practices for Criticality Analysis

• Involve the right people: Include operations, maintenance, safety, and finance. Cross-functional input improves accuracy and acceptance.
• Use data when available: Base scores on actual failure history, MTBF, and downtime cost, not guesses.
• Consider dependencies: Think about cascading failures. A support system may be low-criticality on its own but critical because other assets depend on it.
• Account for safety: Safety-critical assets deserve high criticality regardless of production impact. Do not downrank safety equipment.
• Be realistic about detection: If you cannot reliably detect failure, increase preventive maintenance frequency or install redundancy.
• Review annually: As assets age, failure likelihood increases. Update criticality scores and adjust maintenance as needed.
• Link to action: Do not just score and file. Use results to adjust maintenance schedules, guide capital spending, and justify condition monitoring investments.

Criticality Analysis Tools and Support

Criticality analysis can be done with spreadsheets, but dedicated tools help. Many CMMS platforms include criticality scoring. Some organizations use specialized reliability software or hire consultants for major facility reviews.

Regardless of tools, the key is discipline: systematic assessment, honest scoring, and commitment to act on results. Half-done analysis is worse than none.

Criticality Analysis vs. Risk Management

Frequently Asked Questions