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Abnormal Situation
A disturbance in an industrial process with which the basic process control system of the process cannot cope. Note: In the context of a hazard evaluation, synonymous with deviation.
Accelerating Rate Calorimetry (ARC)
A technique in which a substance is heated in stages until very slow decomposition [or other reaction] is detected. The substance is then held under adiabatic conditions and the course of the decomposition [or other reaction] is monitored. (Also the name of a commercial test apparatus.) [Barton and Rogers 1997]
Acceptable Risk
The average rate of loss that is considered tolerable for a given activity.
Acceptance criteria
Technical basis used to determine whether equipment is deficient (e.g., when analyzing inspection, testing, and preventive maintenance [ITPM] results).
Accident
For Laboratories: An event that can cause (or has caused) harm to workers and property within the laboratory facility.
For Industry: An event that can cause (or has caused) significant harm to workers, the environment, property, and the surrounding community. See Incident.
Accident Prevention Pillar
A group of mutually supporting RBPS elements. The RBPS management system is composed of four accident prevention pillars: (1) commit to process safety, (2) understand hazards and risk, (3) manage risk, and (4) learn from experience.
Accident-Initiated Event
An event (or the first event in an event sequence) that is caused by a movement-related transportation accident, such as a train derailment or a barge grounding.
Accidental Chemical Release
An unintended or sudden release of chemical(s) from manufacturing, processing, handling, or on-site storage facilities to the air, water, or land.
Action Tracking
A method of logging progress when implementing a task or set of tasks.
Active Equipment
Denotes physical motion or activity in the performance of the equipment's function, as with rotating machinery.
Active System
A system in which failures during normal operations are detected immediately.
Acute
A single, short-term exposure (less than 24 hr)
Acute Effect
An adverse effect on a human or animal body, with severe symptoms developing rapidly and coming quickly to a crisis. See also, "Chronic". Importance: How much and how long one is exposed to a chemical is the critical factor to how adverse the health effects will be.
Adiabatic Temperature Rise
Maximum increase in temperature that can be achieved. This increase only occurs when the substance or reaction mixture decomposes completely and at adiabatic conditions.
Administrative control
Procedures that will hold human and/or equipment performance within established limits.
Administrative Controls
Procedural mechanism for controlling, monitoring, or auditing human performance, such as lock out/tagout procedures, bypass approval processes, car seals, and permit systems.
Aggregate Risk
Societal risk for on-site workers in occupied buildings (API 752).
Aggregation
The statistical combination of several data points to form a single data point and confidence interval.
ALARP
As Low As Reasonably Practicable
The concept that efforts to reduce risk should be continued until the incremental sacrifice (in terms of cost, time, effort, or other expenditure of resources) is grossly disproportionate to the incremental risk reduction achieved. The term As Low As Reasonably Achievable (ALARA) is often used synonymously.
Anomaly
An unusual, abnormal, or irregular set of circumstances that left unrecognized or uncorrected may result in an incident.
Antistatic
Having the ability to dissipate charge at a sufficient rate to prevent hazards or nuisances under the conditions of use.
Apparent Activation Energy
In practice, reaction rates are often determined by physical processes (e.g. mass flow, diffusion, mass transfer area) as well as by chemical processes. The activation energy observed in these cases is called the apparent activation energy.
Apparent cause analysis (ACA)
A less formal investigation method that focuses on the immediate causes of a specific incident.
Appearance and Odor
The physical properties of a chemical, such as color and smell. Importance: Knowing what chemicals look and smell like allows an employee to recognized unsafe working conditions.
Apportionment
The subdividing of a risk criterion among a number of risk sources (for example, among all process units at an operating site). The concept of risk apportionment can apply to both individual and societal risk, but at different levels in the enterprise.
Approved Independent Safety Layer (AISL)
Is one layer of a system or subsystem considered adequate protection, in whole or in part, against a specific hazard. An AISL: Is generally one of a number of AISL required as protection against a specific hazards. Cannot be contaminated by the failure of another AISL. Is totally independent of any other AISL. May be a chemical or mechanical design alternate. Must be an "approved mature" EMR, PC, DCS, or microcomputer if electrical controls are used. Must have EMR, PC, DCS or microcomputer with the necessary safety features. Must be able to pass tests for today's process hazard analysis. Is generally one of a number of AISL required as protection against a specific hazards
As Low As Reasonably Practicable
See ALARP
Asphyxiant
A vapor or gas which can cause unconsciousness or death by suffocation (lack of oxygen). Most simple asphyxiants are harmful to the body only when they become so concentrated that they reduce oxygen in the air (normally about 21%) to dangerous levels (19.5% or lower). Importance: Asphyxiation is one of the principal potential hazards of working in confined spaces.
Asset
A process area or facility involved in the use, storage, manufacturing, handling, or transport of chemicals.
The equipment, such as vessels, piping systems, controls, safety systems, utilities, structures and other elements in the process area or facility.
Asset Category
Assets may be categorized in many ways, including people, chemicals, information, environment, equipment, facilities, and activities/operations.
Asset integrity
The condition of an asset that is properly designed and installed in accordance with specifications and remains fit for purpose.
Asset Integrity and Reliability
CCPS RBPS Element 10: This Element helps ensure that equipment is properly designed, fabricated, installed, commissioned, and maintained during its useful life.
Asset Integrity Management (AIM)
A process safety management system for ensuring the integrity of assets throughout their life cycle.
Assumed Risk
A risk that has been identified, analyzed, and accepted at the appropriate management level, unanalyzed or unknown risks fall under oversight and omissions by default.
Atmospheric Boundary Layer
The layer about 1000 m deep next to the ground that is strongly affected by diurnal variations in surface conditions such as ground temperature.
Atmospheric Dispersion
The mixing of a gas or vapor with air at atmospheric conditions ((1 atm, 77 F)
Atmospheric Stability
A measure of the degree of atmospheric turbulence commonly defined in terms of the vertical temperature gradient. In neutral stability the gradient is equivalent to the Adiabatic Lapse Rate (ALR). Stable atmospheric conditions refer to a gradient less than the ALR (ultimately to a temperature inversion), and unstable conditions to a gradient greater than the ALR.
Atmospheric Tank
A storage tank that has been designed to operate at pressures from atmospheric through 0.5 psig measured at the top of the tank. (NFPA30)
Atmospheric Transport and Dispersion model
A model that follows the movement and dilution of a pollutant after it is released into the atmosphere (Hanna et al., 1982).
Atmospheric Turbulence
Random and rapid fluctuations in wind components, which determine the rate of turbulent dispersion or spread of the cloud. Typically expressed by the turbulent velocity (averaging about 1 m/s), which is the standard deviation of rapid fluctuations in wind speed.
Audit
A systematic, independent review to verify conformance with prescribed standards of care using a well-defined review process to ensure consistency and to allow the auditor to reach defensible conclusions.
Audit (process safety audit)
An inspection of a plant or process unit, drawings, procedures, emergency plans, and/or management systems, etc., usually by an independent, impartial team. (See "Safety Review" for contrast.)
Audit Trail
The proof that systematic documentation of activities was performed in a way that allows an auditor to confirm compliance with required or desired organizational behavior.
Auditability
The ability to inspect information, documents, and procedures that demonstrate the adequacy of and adherence to the design, inspection, maintenance, testing, and operation practices used to achieve the other core attributes.
Auditing
CCPS RBPS Element 19: This Element is the system used to schedule, perform, and document periodic audits of the CCPS RBPS Elements, including tracking corrective actions to closure.
Authority Having Jurisdiction
The organization, office, or individual responsible for approving equipment, materials, an installation, or a procedure.
Autocatalysis
The increase of the rate of reaction due to the catalyzing effect of the reaction products. (HSE 2000)
Autodecomposition
The sustained decomposition of a substance without introduction of any other apparent ignition source besides thermal energy and without air or other oxidants present. Autodecomposition is the result of a thermal self-decomposition reaction for given initial conditions (temperature, pressure, volume) at which the rate of heat evolution exceeds the rate of heat loss from the reacting system, thus resulting in an increasing reaction temperature and reaction rate. CCPS 1995b
Autodecomposition Temperature
The minimum temperature for a specified test method, test apparatus (including material of construction and test volume) and initial pressure required to initiate self-sustained decomposition of a solid, liquid or gaseous substance without any other apparent source of ignition and without air or other oxidants present. CCPS 1995b
Autoignition temperature
The lowest temperature at which a fuel/oxidant mixture will spontaneously ignite under specified test conditions.