What constitutes a 'Safety Critical Element (SCE)'?

A Safety Critical Element (SCE) is a component, system, or piece of equipment whose failure could cause or contribute to a major accident hazard (MAH), such as a fire, explosion, or uncontrolled release of hazardous substances. SCEs are essential for preventing or mitigating the consequences of major accidents and are subject to rigorous performance standards and inspection regimes. An SCE is identified through a hazard identification and risk assessment process, which evaluates the potential hazards associated with the operation of a facility. If the failure of a particular item could lead to a major accident, it is classified as an SCE. Examples of SCEs include emergency shutdown (ESD) systems, fire and gas detection and suppression systems, pressure relief valves, blowout preventers (BOPs), structural components, and safety-related control systems. SCEs are subject to specific performance standards that define the required level of reliability and availability. These standards are used to guide the design, maintenance, testing, and inspection of the SCEs. For example, a fire and gas detection system on an offshore platform is an SCE because its failure to detect a gas leak or fire could lead to a major explosion or fire. This system would be subject to rigorous testing and maintenance requirements to ensure its reliability.