Asset Criticality Ranking
How is the Risk Priority Number (RPN) calculated in ACR?
RPN = (Weighted Consequence of Failure Score) × (Probability of Failure Score).
What four factors define a defensible ACR?
Safety/environmental consequence, production impact, asset replaceability, and failure probability.
Why is detectability included in ACR?
It adjusts the risk score by how likely a fault can be detected before functional failure, reducing expected consequences if early detection is possible.
Asset Criticality Ranking (ACR) is a structured, data-driven methodology that objectively quantifies an asset’s importance by calculating a numerical criticality score based on the consequence of failure (safety, environmental, production, quality, cost) multiplied by the probability of failure (reliability) and adjusted for detectability.
In shop floor maintenance, ACR is applied by a cross-functional team (operations, safety, maintenance SMEs) scoring each asset on agreed criteria like safety consequence, production impact, replaceability, and failure probability using a standardized scale. Scores are grouped into tiers (Critical, Essential, Non-essential) to assign maintenance strategies: Critical assets receive predictive/condition-based monitoring, Essential get preventive maintenance, and Non-essential may be run-to-failure. Results are integrated into the CMMS (e.g., ServiceGrid) to prioritize work orders, allocate capital, and drive reliability improvement programs.
Perception-based ranking: Assigning criticality based on gut feeling or recent breakdowns rather than documented risk data, leading to misallocated maintenance budgets.
Infrequent reviews: Failing to update rankings annually or after process changes/capacity additions, causing outdated strategies for newly critical assets.
Inconsistent scoring criteria: Using vague or non-standardized criteria across teams, resulting in unreliable tier cutoffs and inconsistent maintenance priorities.