Industry Application and Benefits of ISO/TR 12489 for Reliability Modelling and Calculation of Safety Systems

Abstract

Abstract The paper presents benefits of applying the ISO technical report ISO/TR 12489, i.e., a document providing guidance for analysts on how to perform reliability modelling and calculation of safety systems. The objective of the paper is to show how this document adds value when used in relevant industries, including oil, gas, and lower carbon energy industries. The benefits are discussed and illustrated using examples of safety systems in gas production, processing, and signal transmission applications. These discussions and examples reflect the broad guidance given in the ISO/TR 12489, covering different approaches and technical challenges within this area with explanations regarding how to solve these. An aim of the ISO technical report is to close a gap between the state-of-the-art and the application of probabilistic calculations for safety systems, where the paper contributes to this aim by illustrating how the ISO technical report applies in practice with focus on the methods and tools covered. Several application areas and benefits are addressed, such as: relevant issues encountered when implementing relevant standards, and particularly the IEC 61508 and IEC 61511; the understanding of key concepts and approaches; the use of simplified approaches; understanding of systemic approaches and demonstration that they can be simpler to implement than so-called ‘simplified formulae’; how to use common standardized models for more complex situations (e.g., reliability block diagrams, fault trees, Markovian approach and Petri nets); and how to assess the frequency of failures. The observations show that the ISO technical report plays a key role in supporting the existing framework in how to perform probabilistic modelling and calculations in a safety context. Safety systems are necessary to protect industrial installations against undesired events. The illustrations given in this paper show how the ISO/TR 12489 can guide assessments leading to acceptable safety levels for protected installations and safer oil and gas industries including lower carbon energy.