Barrier Functions
Barriers
Section titled “Barriers”Barriers are measures intended to identify conditions that may lead to failure, hazard and accident situations, prevent an actual sequence of events occurring or developing, influence a sequence of events in a deliberate way, or limit damage and/or loss. Barrier are sometimes referred to as Safety and Environmental Critical Barriers (SECBs).
What is a barrier function?
Section titled “What is a barrier function?”A barrier function is the task or role of a barrier. Each barrier function is implemented through one or more barrier elements, also known as Safety and Environmental Critical Elements (SECEs) — the physical or logical components that carry out the function. For example, a barrier function of “prevent overpressure” might be implemented through a combination of pressure transmitters, high-pressure trip logic, and pressure safety valves.
What is a barrier element?
Section titled “What is a barrier element?”A barrier element is a technical, operational or organizational measure involved in the realization of a barrier function.
While a barrier function is the purpose or role the barrier is meant to perform, such as prevent, control, or mitigate an unwanted event. A barrier element is the actual component or measure that helps deliver that function, such as equipment, a device, or a procedural step.
The function is “what it does,” while the element is “what provides it”. For example, preventing leakage is a barrier function, while a valve, seal, or operating procedure can be a barrier element contributing to that function.
How barrier functions relate to areas and hazards
Section titled “How barrier functions relate to areas and hazards”Barrier functions are associated with both the area they protect and the major accident hazards they relate to. This means a single barrier function can appear in multiple views within the BSP — by area, by hazard, or by performance standard.
Types of barrier functions:
Section titled “Types of barrier functions:”Barrier functions can be technological (e.g. a control system trip), physical (e.g. a valve), or operational (e.g. a procedure or competency requirement).
Types of barrier elements:
Section titled “Types of barrier elements:”Technical - The equipment or system that helps achieve the barrier function, such as hardware, machinery, or safety systems
Organisational – Personnel with defined roles, responsibilities, and competence needed to make the barrier work.
Operational – The action or activity those people must carry out to realise the barrier function.
| For example: | |
|---|---|
| Barrier function: | Time to safely evacuate personnel |
| Technial barrier element: | Capacity of the means of evacuation e.g. alarm noise level |
| Organisational barrier elements: | Specific competence required for personnel e.g. participation frequency in safety drills |
| Operational barrier element: | Criteria for warning/informing e.g. time requirements |
Barrier Hierarchy:
Section titled “Barrier Hierarchy:”The Eigen Barrier Status Panel will often use the following barrier hierarchy to display information visually.
- Area – The protected area being viewed.
- Barrier Function – The high level protective objective associated with a specific hazard.
- Any Barrier Sub-Functions - This is a sub-function of the barrier function above it, representing a more specific protective activity that contributes to preventing the hazard.
- Barrier Element - This is the barrier element, the specific operational control that implements the sub-function.
Refer to sunburst section for a worked example.