Risk-Based Inspection(RBI)

Risk-Based Inspection standard — provides guidance on developing and implementing a risk-based inspection program for fixed equipment in the hydrocarbon and chemical process industries. It defines the framework for assessing probability and consequence of failure to prioritize inspection resources.

Risk-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.

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.

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.

A 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.

A 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.

The time period between successive inspections of an equipment item, determined by the RBI risk ranking, the remaining life, and applicable code requirements. API 510/570 set maximum intervals but allow extension based on RBI assessments. The inspection interval must not exceed half the remaining life (for general thinning) and should be set at less than half the P-F interval for condition monitoring tasks.