Preventing & Mitigating

Explanation of prevention vs mitigation in the context of MAH

The BSP adheres to the “Bow-tie” methodology for managing Major Accident Hazards (MAH).

Prevention (Left Side):  Controls designed to stop a scenario from leading to a hazard. For a gas leak (Loss of Containment), this includes overpressure sensors and dropped-object protections.

Mitigation (Right Side):  Controls that reduce consequences after a hazard occurs. Examples include fire extinguishing systems, emergency ventilation, and evacuation procedures.

How BSP represents both

A barrier function is the protective function put in place to prevent a major accident hazard from occurring, or to mitigate its consequences if it does. Barrier functions are sometimes referred to as Safety and Environmental Critical Barriers (SECBs).

Each barrier function is implemented through one or more barrier elements, 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.

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). The BSP represents all of these within the barrier model.