Accident, Accident Event Sequence
An unplanned event or sequence of events that has an undesirable consequence.
Aggregate Threshold Quantity
The total amount of a particular hazardous chemical contained in vessels that are
interconnected, or contained in a process and nearby unconnected vessels that may be
adversely affected by an incident at that process.
A storage tank that has been designed to operate at pressures from atmospheric pressure 1.01
x 106 dynes/cm2 (14.7 psia) through 1.05 x 106 dynes/cm2 (15.2 psia).
Audit (Process Safety Audit)
An inspection of a plant or process unit, drawings, procedures, emergency plan, and/or
management systems by an independent team.
That portion of a chemical plant in which the actual processes are carried out, as distinguished
from storage buildings, offices, and other subordinate structures.
The initial temperature at which a liquid begins to pass into the gaseous phase at a pressure of
1.01 x 106 dynes/cm2 (14.7 psia). If an accurate boiling point is not available, see ASTM
A major uncontrolled emission, fire, or explosion, involving one or more highly hazardous
chemicals, that presents serious danger to employees in the workplace or to the public.
To exchange information and solicit input and participation from workers and their
representatives in developing a written employee action plan and process hazard analyses;
and to provide employees with access to information required under the Rule.
For the purposes of this document, contractor in the PSM Rule refers to DOE subtier
contractors, i.e., subcontractors of DOE contractors.