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Layers of Protection Analysis
Layers of Protection Analysis (LOPA)
Understanding Risk with Layers of Protection Analysis
Layers of Protection Analysis (LOPA) serves as a valuable tool for assessing the risk associated with major accidents. While it is predominantly employed within process industries, its underlying methodology is applicable to a wide range of risk assessments. LOPA utilises a semi-quantitative approach, providing ‘order-of-magnitude’ approximations for frequency estimates and, consequently, the risk related to specific event consequences. These risk estimates are confined to the particular scenarios under consideration and focus solely on credible worst-case scenarios.
- As a risk assessment technique, LOPA occupies an intermediate position between basic qualitative methods (such as simple risk matrices) and comprehensive Quantitative Risk Assessment (QRA)
- It is particularly well-suited to situations requiring greater risk quantification due to high potential consequence severity, yet not necessitating a full quantitative analysis
- LOPA offers transparent connections between causes, controls and outcomes, evaluates the effectiveness of individual controls and enables demonstration of control adequacy using straightforward risk criteria – an essential component of any major hazard safety case.
Layers of Protection Analysis (LOPA)
LOPA in Practice
A central element of the LOPA methodology involves identifying ‘preventative’ controls that avert hazards from resulting in accidents (the loss of control event), as well as ‘mitigating’ controls that reduce the magnitude or severity of incidents once they occur. Collectively referred to as ‘layers of protection’, these measures are explicitly recognised and assigned probabilities of failure, based on their assessed effectiveness and reliability. By combining the estimated frequency of initiating events with the probability of control failures, LOPA produces frequency estimates for accident outcomes. These estimates may then be compared to established risk acceptance criteria and, if appropriate, visualised using a risk matrix.
- When further risk reduction is required, the LOPA method helps to identify the performance level required for additional or alternative controls to achieve risk targets
- LOPA results can also specify requirements like SIL for safety systems and may be shown in bowtie diagrams for clear communication (such studies are typically carried out in small workshops that balance technical and operational expertise)
- R4Risk’s facilitators have experience across various industries and provide support including a technical secretary and software for documenting LOPA results
Layers of Protection Analysis (LOPA) Webinars
Related Webinars
R4Risk Webinars
LOPA – What Is It and Why Would I Use It
An online, live training course (i.e. not pre-recorded) that covers the principles underlying Layers of Protection Analysis and its use in risk management events
