Consequence of Failure(CoF)
Definition
A measure of the impact resulting from an equipment failure, encompassing safety (personnel injury/fatality), environmental (release to atmosphere/ground/water), production (lost throughput and business interruption), and equipment (repair/replacement cost). CoF is evaluated based on the worst credible release scenario, considering fluid properties, operating conditions, detection and isolation systems, and the surrounding environment.
Guide
Context
The second axis of the RBI risk matrix. CoF is typically the more persistent risk driver because it is largely determined by the equipment's function, contents, and location — factors that cannot easily be changed. In Reliatic, CoF is stored as 'consequence_of_failure' (1-5) with database CHECK constraints.
Formula
CoF = max(safety consequence, environmental consequence, production consequence) per API 581
Examples
- A large-bore process line containing high-pressure H2S-rich gas adjacent to a control room has CoF 5 due to the potential for multiple fatalities in a toxic release scenario.
- A low-pressure utility water line in an open area has CoF 1 because failure consequences are limited to minor water release and localized repair costs.
Applicable Standards
- API 581
- API 580
- ISO 31000:2018
Related Terms
A quantitative or semi-quantitative measure of the likelihood that an equipment item will fail within a specified time period. PoF is determined by the generic failure frequency of the equipment type, modified by damage factors that account for specific active degradation mechanisms, and adjusted by a management system factor reflecting the quality of the facility's integrity management program.
Risk MatrixA two-dimensional grid that combines Probability of Failure (PoF) on one axis and Consequence of Failure (CoF) on the other to produce a visual risk ranking. The matrix divides risk into categories (typically A through E or Low/Medium/High/Very High/Extreme) that determine inspection priority, interval, and strategy. Risk matrices provide a standardized framework for comparing and prioritizing risks across diverse equipment populations.
Risk RankingA categorical classification (typically A through E) derived from the risk matrix that represents the combined probability and consequence of failure for an equipment item. Risk ranking determines the urgency and extent of inspection, monitoring, and maintenance activities. Rankings are typically: A (lowest risk) through E (highest risk), each with prescribed inspection strategies and maximum interval limits.
Risk-Based Inspection(RBI)A methodology that uses risk assessment to prioritize and plan inspection activities for pressurized and other equipment. RBI combines Probability of Failure (driven by damage mechanisms and equipment condition) with Consequence of Failure (driven by process hazards and safety impact) to rank equipment by risk and allocate inspection resources where they will have the greatest impact on risk reduction.
API 581Risk-Based Inspection Technology — provides the quantitative methodology for calculating probability of failure (PoF) and consequence of failure (CoF) for pressurized equipment. It includes detailed procedures for determining damage factor, management system factor, generic failure frequency, and consequence areas for toxic, flammable, and environmental releases.
Failure EffectThe consequence of a failure mode on the operation, function, or status of the item and the system. Failure effects describe what happens when the failure mode occurs, traced from the local effect on the component through the system level to the end effect on the plant, safety, and environment. Effects must be described assuming no detection or compensating provisions are in place.
Where this appears in Reliatic
This concept is used in the FMEA & Risk module.