Glossary cont'd - DOE-HDBK-1100-20040012

DOE-HDBK-1100-2004

Probability

An expression of the expected likelihood of occurrence of an event or event sequence during an interval of time,

or the likelihood of the success or failure of an event on test or on demand. By definition probability must be

expressed as a number ranging from 0 to 1.

Process

Any onsite activity that involves a highly hazardous chemical, including any use, storage, manufacturing,

handling, or movement of a highly hazardous chemical, or combination of these activities. Any interconnected

group of vessels is considered a single process. Vessels with no physical interconnections located such that an

accident in one vessel could spread to adjacent vessels are considered a single process.

Process Hazard

An inherent chemical or physical characteristic with the energy potential for damaging people, property, and/or

the environment.

Process Hazards Analysis (PrHA)

The application of one or more analytical methods to identify and evaluate process hazards for the purpose of

determining the adequacy of or need for control measures.

Process Safety Management

The application of management principles, methods, and practices to prevent and control accidental releases of

process chemicals or energy.

PSM Rule

The Occupational Safety and Health Administration's rule "Process Safety Management of Highly Hazardous

Chemicals," 29 CFR 1910.119.

Risk

The quantitative or qualitative expression of possible loss that considers both the probability that a hazard will

result in an adverse event and the consequences of that event.

Threshold Quantity

As defined in 29 CFR 1910.119, the minimum amount of a toxic, reactive, or flammable chemical judged by

OSHA as capable of causing a catastrophic event. The threshold quantity triggers application of the rule's

requirements.

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