Process Safety Definitions
An unplanned event or sequence of events that results in an undesirable consequence. The scope of the accident description is arbitrary.
What is an accident?
Determination of the mechanisms causing a potential incident and evaluation of the incident outcomes or consequences.
What is Hazard Analysis?
A leak in a pressurized vessel containing 500 kg of ammonia.
What is an accident
A Hazard and Operability (HAZOP) study was completed on the distillation column
What is a hazard evaluation?
A measure of human injury, environmental damage, or economic loss in terms of both the incident likelihood and the magnitude of the loss or injury.
What is a risk?
A fractional probability that a particular event occurs.
What is a conditional modifier
Identification of material, process, and plant characteristics that can produce undesirable consequences through the occurrence of an incident.
What is Hazard Identification?
The probability of a flammable release being ignited is 0.10?
What is a conditional modifier?
The chemicals in the process are toxic and flammable hazards.
What is Hazard identifcation?
A detailed fault tree and event tree analysis of the process resulted in an overall risk estimate
What is a risk analysis?
A measure of the expected effects of a specific incident outcome case.
What is a consequence
A measure of the ultimate loss and harm of an incident.
What is impact?
A 10 kg/s ammonia leak results in a toxic cloud downwind.
What is a consequence?
A 10 kg/s ammonia leak produces a downwind toxic vapor cloud resulting in local evacuations, an emergency response, plant downtime, and loss of community support.
What is impact
The plant added additional fire protection after completion of the risk analysis.
What is a risk assessment?
A fractional probability that a particular circumstance exists. It accounts for the time-at-risk
What is an enabling conditions?
The basic description of 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.
What is an incident?
The probability of the ambient temperature being low enough to cause a water line to freeze is 0.10
What is an enabling condition?
A plant incident involves a leak of 10 kg/s of ammonia producing a toxic vapor cloud
What is an incident?
The plant decided after completion of the risk analysis that the risk is below their acceptable risk criteria.
What is risk tolerance?
An inherent chemical or physical characteristic that has the potential for causing damage to people, the environment, or property.
What is a Hazard?
The description of the physical manifestation of the incident. This could include toxic release, fire, explosion, and so on.
A pressurized tank containing 500 kg of ammonia
What is a hazard?
A leak in an ammonia pipeline results in a toxic release.
What is an incident outcome?
Design features, equipment, procedures, and other resources in place to decrease the probability of an initiating cause or mitigate the severity of a loss impact.
What is a Safeguard?