Hazard
An inherent chemical or physical characteristic that has the potential for causing damage to people, property, or the environment.
Hazard Analysis
The identification of undesired events that lead to the materialization of a hazard, the analysis of the mechanisms by which these undesired events could occur and usually the estimation of the consequences.
Hazard and Operability Study (HAZOP)
A systematic qualitative technique to identify process hazards and potential operating problems using a series of guide words to study process deviations. A HAZOP is used to question every part of a process to discover what deviations from the intention of the design can occur and what their causes and consequences may be. This is done systematically by applying suitable guidewords. This is a systematic detailed review technique, for both batch and continuous plants, which can be applied to new or existing processes to identify hazards.
Hazard Checklist
An experience-based list of hazards, potential incident situations, or other process safety concerns used to stimulate the identification of hazardous situations for a process or operation.
Hazard Evaluation
Identification of individual hazards of a system, determination of the mechanisms by which they could give rise to undesired events, and evaluation of the consequences of these events on health (including public health), environment and property. Uses qualitative techniques to pinpoint weaknesses in the design and operation of facilities that could lead to incidents.
Hazard Identification
Part of the Hazards Identification and Risk Analysis (HIRA) method in which the material and energy hazards of the process, along with the siting and layout of the facility, are identified so that a risk analysis can be performed on potential incident scenarios.
Hazard Identification and Risk Analysis (HIRA)
CCPS RBPS Element 07: This Element addresses potential scenarios of what could go wrong by identifying the hazards, evaluating their risks, and determining if additional safeguards are needed.
Hazard Identification and Risk Analysis (HIRA)
A collective term that encompasses all activities involved in identifying hazards and evaluating risk at facilities, throughout their life cycle, to make certain that risks to employees, the public, or the environment are consistently controlled within the organization's risk tolerance.
Hazard Zone
For an incident that produces an outcome such as toxic release, the hazard zone is the area over which the airborne concentration equals or exceeds some level of concern. For a flammable release, the area of effect is based on a specified level of thermal radiation. For a release that results in explosion, this is the area defined by specified overpressure levels.
Hazardous Chemical
A material that is toxic, reactive, or flammable and is capable of causing a process safety incident if released. Also Hazardous material.
Hazardous Chemical Reactivity
Any chemical reaction with the potential to exhibit rates of increase in temperature and/or pressure too high to be absorbed by the environment surrounding the system. Included are reactive materials and unstable materials.
Hazardous Material
In a broad sense, any substance or mixture of substances having properties capable of producing adverse effects to the health or safety of human beings or the environment. Material presenting dangers beyond the fire problems relating to flash point and boiling point. These dangers may arise from, but are not limited to, toxicity, reactivity, instability, or corrosivity
HAZOP/LOPA Study
The extension of a HAZOP Study to include aspects of a LOPA, including selecting identified scenarios for further analysis; evaluating the initiating event frequency, consequence severity and effectiveness of IPLs on an order-of-magnitude basis; considering enabling conditions and/or conditional modifiers as appropriate when evaluating scenario risk; and comparing the calculated scenario risk to a risk goal to determine the adequacy of existing risk control measures.
Health Hazard
A chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees. (OSHA 1994)
Heat of Combustion, Hci
The heat of reaction obtained by burning a unit mass of
Heat of Reaction
The net difference in heat of formation of all reactants and of all products in an adiabatic system. The reaction is exothermic if heat is released (heat of reaction is negative), and endothermic if heat is absorbed by the reaction.
Heavy Gas
A gas with density exceeding that of air at ambient temperature. See also dense gas and negatively buoyant vapors.
High Potential Incident
An event that, under different circumstances, might easily have resulted in a catastrophic loss
Highly Hazardous chemical
A material that is toxic, reactive, or flammable and is capable of causing a process safety incident if released. These materials are included in OSHA's PSM Standard, 29 CFR 1910.119.
Historical Data
Data recorded from actual past experience.
Hot Work
Any operation that uses flames or can produce sparks (e.g., welding).
Human Error
Intended or unintended human action or inaction that produces an inappropriate result. Includes actions by designers, operators, engineers, or managers that may contribute to or result in accidents.
Human Error Probability
The ratio between the number of human errors and the number of opportunities for human error. Synonyms: human failure probability and task failure probability.
Human Factors
A discipline concerned with designing machines, operations, and work environments so that they match human capabilities, limitations, and needs. Includes any technical work (engineering, procedure writing, worker training, worker selection, etc.) related to the human factor in operator-machine systems.
Human Reliability Analysis (HRA)
A method used to evaluate whether system-required human-actions, tasks, or jobs will be completed successfully within a required time period. Also used to determine the probability that no extraneous human actions detrimental to the system will be performed.
Hybrid Mixture
A mixture of a flammable gas with either a combustible dust or combustible mist.
Hypergolic
Hypergolic behavior is characterized by immediate, spontaneous ignition of an oxidation reaction upon mixing of two or more substances.
Ignitable Mixture
A flammable gas, mist, or dust mixture or any combination of these that can be ignited by a specified ignition source such as a static spark.
Ignition
Self-sustained flame propagation caused by a static discharge in a flammable mixture.
Ignition Energy
Energy in Joules stored in a capacitor which upon discharge is just sufficient to effect ignition of a given fuel mixture under specified test conditions (Methods: ASTM 582 for Gas Mixtures)
Immediately Dangerous to Life or Health
An atmospheric concentration of any toxic, corrosive, or asphyxiant substance that poses an immediate threat to life or would cause irreversible or delayed adverse health effects or would interfere with an individual's ability to escape from a dangerous atmosphere. [29 CFR* 1910.120]
Impact
A measure of the ultimate loss and harm of a loss event.
Note: Impact may be expressed as the number of injuries and/or fatalities, the extent of the environmental damage, or the magnitude of the loss, such as property damage, material loss, production loss, market share loss, and recovery costs.
Implementation
Completion of an action plan associated with the outcome of the process of resolving audit findings, incident investigation team recommendations, risk analysis team recommendations, and so forth. Also, the establishment or execution of PSM program element work activities.
Impulse
The area under the overpressure-time curve for explosions. The area can be calculated for the positive phase or negative phase of the blast.
Incident
An event, or series of events, resulting in one or more undesirable consequences, such as harm to people, damage to the environment, or asset/business losses.
Note: Such events include fires, explosions, releases of toxic or otherwise harmful substances, runaway reactions, etc.
Incident investigation
A systematic approach for determining the causes of an incident and developing recommendations that address the causes to help prevent or mitigate future incidents. See also Root cause analysis and Apparent cause analysis.
Incident Investigation Management System
A written document that defines the roles, responsibilities, protocols, and specific activities to be carried out by personnel performing an incident investigation.
Incident Investigation Team
a group of qualified people who examine an incident in a manner that is timely, objective, systematic, and technically sound to determine that factual information pertaining to the event is documented, probable cause(s) are ascertained, and complete technical understanding of such an event is achieved.
Incident Investigations
CCPS RBPS Element 17: This Element is the system used to identify, investigate, and document incidents, including tracking corrective actions to closure.
Incident Outcome
The physical manifestation of the incident: for toxic materials, the incident outcome is a toxic release, while for flammable materials; the incident outcome could be a boiling liquid expanding vapor explosion (BLEVE), flash fire, vapor cloud explosion (VCE), etc. For example, the incident outcome for a leak of chlorine from a railcar is a toxic release.
Incident Sequence
A series of events composed of an initiating event and intermediate events leading to an undesirable outcome.
Incident Warning Sign
An indicator of a subtle problem that could lead to an incident.
Incipient failure
An imperfection in the state or condition of hardware such that a degraded or catastrophic failure can be expected to result if corrective action is not taken.
Incompatible
The term can refer to any undesired results occurring when substances are combined. In the context of this publication, it refers to incompatible substances giving an undesired chemical reaction when combined, posing a chemical reactivity hazard under a defined scenario.
Independent Protection Layer (IPL)
A device, system, or action that is capable of preventing a scenario from proceeding to the undesired consequence without being adversely affected by the initiating event or the action of any other protection layer associated with the scenario.
Note: There are specific functional criteria for protection layers that are designated as "independent." A protection layer meets the requirements of being an IPL when it is designed and managed to achieve the following seven core attributes: Independent; Functional; Integrity; Reliable; Validated, Maintained and Audited; Access Security; and Management of Change.
Individual Risk
The risk to a person in the vicinity of a hazard. This includes the nature of the injury to the individual, the likelihood of the injury occurring, and the time period over which the injury might occur.
Induction Period/Time
Time interval (starting at operating conditions) after which a runaway shows its maximum effects.
Inert
A chemical that does not react chemically with other substances. (Cambridge online)
Inert Gas
A nonflammable, nonreactive gas that can be used to render the combustible material in a system incapable of supporting combustion.
Inerting
A technique by which a combustible mixture is rendered non-ignitable by addition of an inert gas or a noncombustible dust. See Oxidant Concentration Reduction.