API 580 key terms

A risk assessment method that uses the likelihood and consequences of equipment failure to prioritize inspection activities and direct resources toward the items that pose the greatest risk.

The combination of the probability that an undesirable event will occur and the severity of the consequences that result, commonly expressed as the product of likelihood and consequence.

The loss of function or the inability of a component to perform its intended purpose within acceptable limits, including loss of containment, leakage, or structural degradation requiring repair or replacement.

The likelihood that equipment or a component will fail within a specified time period, usually expressed as a frequency such as events per year.

The outcome or impact produced by a failure event, measured in terms of harm to people, environmental damage, property loss, and business interruption.

The physical, chemical, or mechanical process that causes deterioration of equipment or materials over time, such as corrosion, erosion, cracking, or fatigue.

The specific manner in which a component loses its function, describing how a damage mechanism ultimately produces failure, for example a pinhole leak, rupture, or deformation.

A numerical value expressing how much a specific damage mechanism raises the likelihood of failure relative to a baseline, adjusted for inspection effectiveness and observed equipment condition.

A published or industry-derived baseline failure rate for a category of equipment, used as a starting point before plant-specific damage and inspection factors are applied.

The speed at which material is lost through chemical or electrochemical attack, usually stated as thickness lost per year, which supports estimates of remaining life.

The estimated time before equipment reaches its minimum allowable thickness or another defined retirement limit under current operating and deterioration conditions.

A planned activity of examination, testing, or monitoring performed to determine equipment condition, detect damage, and confirm that the item remains fit for continued service.

A measure of how reliably a given inspection technique, coverage level, and timing can detect a specific damage mechanism and thereby reduce the probability of failure.

A documented schedule stating which equipment will be inspected, which techniques will be applied, when inspections will occur, and what coverage is needed to manage identified risks.

The period of time between successive inspections of an item, set so that expected damage is detected before it can develop into a failure.

The process of ordering equipment or components from highest to lowest risk so that inspection and mitigation resources are directed to the most critical items first.

A chart plotting likelihood categories against consequence categories to display resulting risk levels and help classify items into bands such as high, medium, or low risk.

Predefined limits that state the level of risk an organization is willing to tolerate, used to judge whether existing risk is acceptable or requires further mitigation.

The specific risk level an organization aims to achieve for an item or area, often set below the acceptance limit to provide a margin of safety.

The potential effect of a failure event on people, the environment, property, and operations, evaluated in categories that reflect the severity and the exposure of the affected area.

The potential for injury or fatality to personnel resulting from a failure event, influenced by the nature of the release, ignition or toxicity, and the number of people exposed.

The potential harm to air, water, soil, or ecosystems from a release of hazardous material, including cleanup cost, regulatory impact, and long-term ecological damage.

The operational and financial impact of a failure, including lost production, repair costs, and downtime, which can be significant even when no safety or environmental harm occurs.

A condition or substance with the potential to cause harm to people, the environment, or assets, such as a flammable, toxic, or pressurized material.

Actions taken to lower either the probability or the consequences of failure, including inspection, maintenance, repair, operational changes, and engineered controls.

A formal process for reviewing and approving changes to equipment, processes, or operating conditions so that risk assessments and inspection plans are updated accordingly.

The periodic review and update of an RBI assessment to reflect new data, inspection findings, operational changes, or evolving damage so that risk estimates remain valid.

A group of personnel with complementary knowledge, typically covering inspection, engineering, operations, and process safety, responsible for conducting and documenting the RBI assessment.

A person with recognized knowledge and experience in a specific technical area, such as damage mechanisms or inspection methods, who provides input to the assessment.

An initial simplified evaluation of equipment that uses limited data to quickly categorize risk and identify items needing a more detailed RBI analysis.

An assessment that relies on descriptive categories, judgment, and expert opinion rather than numerical values to estimate the likelihood and consequence of failure.

An assessment that combines numerical indices with judgment to estimate likelihood and consequence, giving more consistency than qualitative methods without full quantitative modeling.

An assessment that uses numerical models and data to calculate probabilities and consequences in physical units, producing a detailed and reproducible estimate of risk.

Information describing an item's design, materials, dimensions, and service history, used to identify relevant damage mechanisms and estimate deterioration and failure likelihood.

Information about operating conditions such as temperature, pressure, fluid composition, and flow that influence the rate of damage and the severity of potential consequences.

The gradual loss of material or performance caused by service conditions, assessed to predict when equipment may no longer meet its required integrity.