preprints.org > engineering > safety, risk, reliability and quality > doi: 10.20944/preprints202406.1433.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 19 June 2024 / Approved: 20 June 2024 / Online: 21 June 2024 (05:13:15 CEST)

Although it’s been some forty years since we started to teach combined modified Fault Tree / Event Tree acyclic digraphs, as much simpler Bow Tie diagrams, their popularity seems undimmed; as their pictorial and focussed discussion prompts, fulfil a valuable function in the safe design and operation of hazardous plants and installations. An excellent review of the current state of the art and an authoritative treatise on the terminology and issues involved has been produced as an internationally recognised standard for using the approach. But just as this model has augmented and helped formalise previous pictorial tools, (such as “Dominoes” and holey “Cheese” slices), this paper suggests and sets out to show how we can build on even this current cornerstone of practice and augment its versatility; with the ability to obtain, what engineers rely on, some more quantitative insights from these pictures. “Layers Of Protection Analysis” (LOPA), has already demonstrated a way of pulling together more quantitative predictions from the pictures. This paper would go further and by concentrating on the function not the physicality of a barrier, outlines a methodology that can extend, not just the quantification ability of the LOPA extension, but present a much more holistic view of how the Barriers, as functions, need to work together, interact and interdepend; often in nonlinear, unexpected ways, to give system designers and operators a much clearer view of actual performance predictions.

Bow Ties and Barriers; LOPA; Risk and FRAM

Engineering, Safety, Risk, Reliability and Quality

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