7.1 The Aim of Process Risk Assessment
161
publications and textbooks developed by the Center for Chemical Process Safety
(CCPS) (AICHE, 2018).
7.1.1 Relevant Terminology
Process risk assessment as introduced in this chapter involves a set of specific
terminology. This section introduces some of the terms most often used, and these
and others are further defined within the CCPS’ Process Safety Glossary (CCPS,
2020).
The assessment of chemical process risks involves a review of accident scenarios,
which consist of (1) process hazards, defined as an unplanned event or sequence of
events that lead to a loss event, and (2) the consequences of the loss event. The
concept of an accident scenario is illustrated in Fig. 7.2.
Within a process, a hazard is an inherent chemical or physical characteristic that
has the potential to cause damage to humans, the environment, or property. Process
hazards are determined by material properties, such as being flammable or toxic,
and by process conditions, such as high temperature or high pressure.
An event by itself is the occurrence or change of a particular set of circumstances.
And the consequence is defined as the undesirable result of an event. An event
becomes a loss event when it is irreversible and results in adverse consequences.
Examples in the chemical industry include the release of hazardous substances, fires,
and explosions. A loss event can have several initiating causes as well as several
consequences.
An initiating cause is the first event that occurs within potentially a sequence of
events leading to a loss. It can be, for example, a process failure, a human error,
or an external event, such as extreme weather conditions. It results in the transition
from a normal situation to an abnormal situation, namely, in a process deviation.
Safeguards refer to any engineered system or administrative control used to
interrupt the sequence of events following an initiating event (known as preventive
safeguards), or to mitigate the consequences (known as mitigative safeguards).
Some examples of safeguards include relief valves, automated control, operator
responses, alarms, vents, and sprinklers.
7.1.2 Chemical Process Safety
The aim of process risk assessment and management is to achieve chemical process
safety, which is based on the guiding principle of inherent safety during the process
design (see Chap. 4) and on functional safety management (CCPS, 2016). Inherent
process safety and functional safety are achieved through applying risk assessment
and management throughout all stages of process development.
161
publications and textbooks developed by the Center for Chemical Process Safety
(CCPS) (AICHE, 2018).
7.1.1 Relevant Terminology
Process risk assessment as introduced in this chapter involves a set of specific
terminology. This section introduces some of the terms most often used, and these
and others are further defined within the CCPS’ Process Safety Glossary (CCPS,
2020).
The assessment of chemical process risks involves a review of accident scenarios,
which consist of (1) process hazards, defined as an unplanned event or sequence of
events that lead to a loss event, and (2) the consequences of the loss event. The
concept of an accident scenario is illustrated in Fig. 7.2.
Within a process, a hazard is an inherent chemical or physical characteristic that
has the potential to cause damage to humans, the environment, or property. Process
hazards are determined by material properties, such as being flammable or toxic,
and by process conditions, such as high temperature or high pressure.
An event by itself is the occurrence or change of a particular set of circumstances.
And the consequence is defined as the undesirable result of an event. An event
becomes a loss event when it is irreversible and results in adverse consequences.
Examples in the chemical industry include the release of hazardous substances, fires,
and explosions. A loss event can have several initiating causes as well as several
consequences.
An initiating cause is the first event that occurs within potentially a sequence of
events leading to a loss. It can be, for example, a process failure, a human error,
or an external event, such as extreme weather conditions. It results in the transition
from a normal situation to an abnormal situation, namely, in a process deviation.
Safeguards refer to any engineered system or administrative control used to
interrupt the sequence of events following an initiating event (known as preventive
safeguards), or to mitigate the consequences (known as mitigative safeguards).
Some examples of safeguards include relief valves, automated control, operator
responses, alarms, vents, and sprinklers.
7.1.2 Chemical Process Safety
The aim of process risk assessment and management is to achieve chemical process
safety, which is based on the guiding principle of inherent safety during the process
design (see Chap. 4) and on functional safety management (CCPS, 2016). Inherent
process safety and functional safety are achieved through applying risk assessment
and management throughout all stages of process development.