Multi-objective optimization of safety instrumented systems maintenance strategy: a case study

Abstract

PurposeThe main objective of safety instrumented systems (SISs) is to maintain a safe condition of a facility if hazardous events occur. However, in some cases, SIS's can be activated prematurely, these activations are characterized in terms of frequency by a Spurious Trip Rate (STR) and their occurrence leads to significant technical, economic and even environmental losses. This work aims to propose an approach to optimize the performances of the SIS by a multi-objective genetic algorithm. The optimization of SIS performances is performed using the multi-objective genetic algorithm by minimizing their probability of failure on demand PFDavg, Spurious Trip Rate (STR) and Life Cycle Costs (LCCavg). A set of constraints related to maintenance costs have been established. These constraints imply specific maintenance strategies which improve the SIS performances and minimize the technical, economic and environmental risks related to spurious shutdowns. Validation of such an approach is applied to an Emergency Shutdown (ESD) of the blower section of an industrial facility (RGTE- In Amenas).Design/methodology/approachThe optimization of SIS performances is performed using the multi-objective genetic algorithm by minimizing their probability of failure on demand PFDavg, Spurious Trip Rate (STR) and Life Cycle Costs (LCCavg). A set of constraints related to maintenance costs have been established. These constraints imply specific maintenance strategies which improve the SIS performances and minimize the technical, economic and environmental risks related to spurious shutdowns. Validation of such an approach is applied to an Emergency Shutdown (ESD) of the blower section of an industrial facility (RGTE- In Amenas).FindingsA case study concerning a safety instrumented system implemented in the RGTE facility has shown the great applicability of the proposed approach and the results are encouraging. The results show that the selection of a good maintenance strategy allows a very significant minimization of the PFDavg, the frequency of spurious trips and Life Cycle Costs of SIS.Originality/valueThe maintenance strategy defined by the system designer can be modified and improved during the operational phase, in particular safety systems. It constitutes one of the least expensive investment strategies for improving SIS performances. It has allowed a considerable minimization of the SIS life cycle costs; PFDavg and the frequency of spurious trips.

Optimization the reliability of emergency safety barriers based on the subjective safety analysis and evidential reasoning theory. Case study

“…Therefore, in 2000, the American Institute of Chemical Engineers (AIChE) developed guidelines for chemical process quantitative risk assessment (CPQRA) for use in the chemical industry. CPQRA provides a quantitative or qualitative method to assess industry risk and identify safety barriers for cost-effective risk reduction (Touahar et al. , 2021).…”

“…Therefore, in 2000, the American Institute of Chemical Engineers (AIChE) developed guidelines for chemical process quantitative risk assessment (CPQRA) for use in the chemical industry. CPQRA provides a quantitative or qualitative method to assess industry risk and identify safety barriers for cost-effective risk reduction (Touahar et al, 2021). Therefore, safety assessment and implementation of risk management of storage tanks should be done to reduce the probability and severity of these scenarios based on the analysis of the results, evaluate their safety status and improve the level of safety management (Van Wingerden, 2000;Davies and Nolan, 2004;Sarvestani et al, 2021).…”