AN EXTENSION OF THE FAILURE MODE EFFECTS AND CRITICALITY ANALYSIS WITH FUZZY ANALYTICAL HIERARCHY PROCESS METHOD TO ASSESS THE EMERGENCY SAFETY BARRIERS

The emergency safety barrier is one of the reactive technical safety barriers in industrial facilities. Degrade of emergency safety barriers can lead to a major accident with serious consequences for people, property and the environment. In this context, the purpose of this article is to present a proposed methodology to identify these deficiencies, thus ensuring the effectiveness of the emergency safety barriers. This paper presents an integrated approach that uses fuzzy set theory, extension of failure modes, effects and criticality analysis and the fuzzy analytic hierarchy process method to deal with uncertainty in decision-making related to the prioritization of risk factors. These risk factors are the prioritization of corrective actions associated with the most critical disturbance modes to improve the reliability of emergency safety barriers. In addition, a Liquefied Petroleum Gas production facility was selected as a case study to assess the emergency safety barriers. The results show that the proposed methodology provides the possibility to evaluate the fire-fighting systems. In addition, the fuzzy analytical approach method is the most reliable and accurate. Therefore, some corrective actions are suggested to reduce the failure criticality of the emergency safety barriers and help practitioners prioritize the improvement of the emergency safety barriers of the Liquefied Petroleum Gas storage facility. This paper has an important role in the dysfunctional analysis of the emergency safety barriers related to the others effects of the release of LPG, such as the effects of domino scenarios

Contribution à la modélisation des systèmes instrumentés de sécurité et à l'évaluation de leurs performances (analyse critique de la norme CEI 61508)

La norme CEI 61508 est le texte de référence dans le domaine de la sécurité fonctionnelle. Les systèmes instrumentés de sécurité (SIS) sont au cœur de cette norme. Notre travail a consisté à analyser les cinq concepts fondamentaux de cette norme que sont les modes de fonctionnement des SIS, dénommés faible demande et demande continue ou élevée , ainsi que leurs attributs respectifs connus sous les noms de probabilité moyenne de défaillance à la demande (PFDmoy) et de probabilité de défaillance par heure (PFH) . Le cinquième concept renvoyant à la relation étroite existant, selon la norme, entre le facteur de réduction du risque apporté par un SIS (RRF) et le niveau d intégrité de sécurité (SIL) qui lui est associé. Nous proposons une nouvelle interprétation des quatre premiers concepts et une certaine remise en cause du cinquième et de la notion de proportion de défaillance en sécurité (SFF). Nous avons de plus proposé deux démonstrations des formules analytiques présentées dans la norme en précisant leur domaine de validité et étudié l influence des défaillances intempestives d un SIS sur la fréquence des accidents qu il est chargé de prévenir.IEC 61508 standard is the reference text related to the so-called functional safety. The safety instrumented systems (SIS) are the core of this standard. Our work dealt with the analysis of its five main concepts, i.e., low and continuous modes of operation of SIS and their attributes known as probability of failure on demand (PFDavg) and probability of failure per hour (PFH). The fifth concept concerns the strong relation existing between the risk reduction factor (RRF) provided by a given layer of protection and the safety integrity level (SIL) of the latter. We propose a new interpretation of the fourth first concepts and some questioning of the fifth and of the safe failure fraction (SFF) notion. Morover we have proposed two ways suitable to demonstrate the analytical formulae given in the standard and to precise their underlying hypothesis. We have also studied the influence of the spurious failures of a given SIS on the accident frequency it must prevent.BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Fiabilité dynamique: Outils analytiques et numériques

National audienc

An Environmental Analysis of the Impact of an Accidental Fire in Process Industries

http://www.bepress.com/ijcre/vol7/A88International audienceThe models to prevent accidents from occurring in process industry, or to minimize the harm if an accident does take place, always revolve around forecasting the likely accidents and their impacts. Based on the several effects of an accident on the environment, the approach used in this study involves a qualitative analysis by the Environmental Effects Analysis (EEA) combined to Quantitative Risk Assessment approach (QRA). In fact, the EEA, under its current formalism, emphasizes environmental effects in normal operations solely. It does not consider abnormal situations (accidental aspects). In order to overcome this lack, the authors propose an extension of the current formalism of the EEA through the inclusion of accidental events that may occur in each phase of the product's life cycle, where from the EEA – Accidental Aspect method. Impacts associated with abnormal situations are identified and assessed in accordance with risk assessment practices. Risk assessment can be both qualitative and quantitative. Nevertheless, whenever possible, we adopt a Quantitative Risk Assessment approach (QRA). The evaluation criteria used in the classical EEA, i.e. Environmental Priority Number (EPN), is redefined to take into account the impacts due to accidental aspects. By doing so, we establish an effective link between methods for assessing environmental impacts and approaches to risk management. The validation of the proposed methodology is made on a storage system with a high potential of fire risk

Piecewise Deterministic Markov Processes based approach applied to an offshore oil production system

This paper is keeping with the topic of two papers which treated dynamic reliability problems and were presented in previous conferences. Its aim is to confirm the potentialities of a method which combines the high modeling ability of the piecewise deterministic processes and the great computing power inherent to the Monte Carlo simulation. This method is now applied to a simplified but realistic offshore oil production system which is a hybrid system combining continuous-time and discrete-time dynamics. The results thus obtained have been compared with those given by an ad hoc Petri net model for comparison and validation purposes

Probabilistic assessment in relationship with safety integrity levels by using Fault Trees

International audienc

Distributed vs. Hybrid Control Architecture Using STPA and AHP - Application to an Autonomous Mobile Multi-robot System

International audienceSystems composed of a fleet of autonomous mobile robots are among the most complex control systems. This control complexity is at a high level especially when those robots navigate in hazardous and dynamic environments such as chemical analysis laboratories. These systems include different dangerous and harmful products (toxic, flammable, explosive...) with different quantity. In order to perform its mission on a regular basis, this multi-robot system can be controlled according to multiple architectures. We propose, firstly, to apply the System Theoretic Process Analysis (STPA) on two selected control architectures, namely distributed and hybrid architectures in order to obtain a set of loss scenarios for each kind of architecture. For further assessment, the Analytic Hierarchy Process (AHP) is used to choose the best architecture. The proposed approach provides a risk analysis and a more practical comparison between the two control architectures of a mobile multi-robot system and facilitates decision-making, even in complex situations

Two-terminal reliability analysis for multi-phase communication networks

Abstract: Most researches of network reliability generally assume that the system structures do not change with time. This paper presents the concept of multi-phase network systems (MPNS) to consider dynamic characteristics of networks, and analyze the reliability of MPNS. MPNS reliability is evaluated through a cross-phase binary decision diagram (BDD). The BDD-based algorithm can act as a platform to consider various components behaviors such as repair and growing pressure. Case study shows that the proposed MPNS concept is an effective description of some practical communication networks, and the cross-phase BDD model is efficient in analyzing MPNS reliability