1,721,090 research outputs found
Assessment of safety barriers and mitigation of domino scenarios
No full textSafety barriers play an important role in accident prevention and mitigation. The severity of domino scenarios usually calls for the displacement of a number of specific safety barriers to manage and reduce the risk due to escalation. However, the quantitative effect of safety barrier performance in managing the risk induced by domino scenarios is seldom addressed, at least in most of the methodologies proposed for domino effect risk assessment. A specific quantitative approach, based on a modified event tree analysis (ETA), is introduced for the probabilistic assessment of escalation accounting for the presence of safety barriers. The procedure considers the quantitative performance of safety barriers by the assessment of two parameters: the probability of failure on demand and the effectiveness of the barrier. The ETA approach and the assessment of barrier parameters are also discussed. In particular, specific gates are proposed for reference target equipment items, to support the ETA. Suggested approaches to barrier probability of failure on demand and effectiveness are presented, and a repository of baseline data for the performance parameters of these barriers is reported. Overall, tools and procedures to support the implementation of quantitative safety barrier performance assessment aimed at including the effect of safety barrier performance in the quantitative assessment of risk due to domino scenarios are presented
Mitigation barriers for domino effect
No full textThis chapter provides a detailed analysis of the safety barriers and systems aimed controlling and/or mitigating risks due to domino effect. A preliminary conceptualization of safety barriers, layered protection, and safety functions is provided, in order to identify and select a reference framework for the description and analysis of safety barriers working principles. In particular, the analysis focuses on inherent, passive, active, and procedural emergency measures. Advantages and limitation of the more commonly applied solutions in industrial contexts are detailed, reporting specific examples for the prevention and mitigation of domino effects triggered by fire heat radiation exposure, explosion overpressure, and fragments projection. Finally, the examination of managerial aspects is carried out, in order to show the necessary policies, strategies, and resources aimed at ensuring the effective performance of safety barriers
Assessment of safety barrier performance in Natech scenarios
Full text linkThe impact of natural hazards on chemical and process facilities may lead to catastrophic technological accidents defined as Natech events. In the present study, a performance assessment of safety barriers during extreme natural events as floods and earthquakes was carried out. Assessing the performance of safety barriers during such complex scenarios is a key issue to identify the final consequences and the evolution of Natech events. Due to the scarcity of available data, an anonymous survey was carried out, involving more than 40 experts of different nationalities and background. Categories of safety barriers highly vulnerable to the impact of natural events were identified. Baseline values for performance modification factors describing how barrier performance may be affected by floods and earthquakes were obtained from the expert elicitation procedure. The results may support the probabilistic analysis of Natech scenarios, in order to achieve a more accurate assessment of final consequences and of possible escalation
The influence of harsh environment in the management of safety barriers
No full textThis chapter is aimed at introducing a structured approach to support the probabilistic assessment of domino effects accounting for the influence of harsh environmental conditions on safety barriers. A specific metric is defined to consider the external factors related to harsh environment on the assessment of safety barriers availability and efficiency. The method proposed addresses both hardware barriers (active and passive systems) and emergency response strategies. The approach is exemplified by its application to two case studies, aimed at the assessment of the influence of harsh environmental conditions on the risk due to cascading events, respectively, in onshore and offshore industrial facilities
Assessing the impact of natural hazards on safety barriers on the basis of expert elicitation
Full text linkNatural hazards pose critical threats to chemical and process installations handling hazardous materials. In particular, severe technological accidents involving the release of chemicals can be triggered by natural events, namely Natech accidents. Moreover, natural hazards can impact and weaken safety measures for accident prevention and mitigation implemented in the impacted plant, increasing the credibility of severe domino effect escalation and, thus, affecting the risk induced by Natech scenarios. The present study is aimed at developing a structured approach aimed at supporting the probabilistic evaluation of Natech events in presence of safety barriers. Barrier performance are described with a specific metric, able to quantitatively assess the degradation due to natural hazards. The methodology is applied to the analysis of an industrial case study, showing the influence of the natural event impact on the performance of safety barriers and, thus, on the probability and frequency of escalation scenarios triggered by Natech events
Mitigation of fire-induced domino scenarios
No full textPrimary fire scenarios are those that most frequently triggered domino effects, causing severe overall escalation scenarios. Due to the potential severity of such scenarios, baseline conventional methods for the quantitative risk assessment of domino effect may lead to overconservative results when applied for their specific assessment. Thus, a specific methodology accounting for the mitigation effects deriving from the introduction of safety barriers in the quantitative assessment of risk due to the escalation of primary scenarios caused by thermal radiation as an escalation vector is introduced in this chapter. The methodology is based on the concepts of availability and effectiveness of safety barriers and on the application of a dedicated event tree analysis. A tutorial showing the application of the methodology and the potential results that may be obtained is also provided
Assessment of safety barrier performance in the mitigation of domino scenarios caused by Natech events
Full text linkTechnological accidents triggered by natural hazards (Natech accidents) are likely to escalate in cascading scenarios with severe consequences. Indeed, safety barriers implemented in process plants to prevent and mitigate accidents may be affected by natural hazards as well. The present study proposes a novel comprehensive method to assess safety barriers and protection systems performance modification during natural hazards, as well as the resulting modification in the expected frequency of secondary technological scenarios that may arise. In particular, the probability and frequency of domino scenarios initiated by Natech events are assessed considering the possible concurrent degradation of safety barrier performance in case of floods and earthquakes. An approach based on layer of protection analysis is adopted to quantify safety barrier performance degradation, accounting for the modification of barrier availability and effectiveness. A dedicated event tree analysis is applied to domino effect assessment and quantification of overall escalation scenarios. The results obtained allowed a detailed assessment of the expected frequency of secondary mitigated escalation scenarios, considering the possible effect of barriers degradation within Natech events
Assessment of risk modification due to safety barrier performance degradation in Natech events
Full text linkNatural hazards may cause severe technological accidents involving hazardous substances (Natech accidents). Along with process equipment also safety critical elements as safety barriers might be impacted by such events, thus reducing the protection provided and the possibility to prevent escalation and cascading effects. In the present study a comprehensive methodology is developed to address the quantitative assessment of the risk caused by the escalation of Natech accidents, specifically addressing the effect of the performance modification of safety barriers caused by the impact of the natural hazard. Barrier performance depletion is modelled through an innovative multi-level approach, and it is then introduced in the quantitative risk assessment procedure by a modified event tree analysis. A demonstrative application of the proposed methodology to a case study is provided, showing a relevant increase in risk figures deriving from the degradation of safety barrier performance caused by natural events. The proposed framework extends the systemic assessment of Natech scenarios to encompass the specific criticalities introduced by safety barrier performance modification induced by natural events, providing a more effective support to decision-making in the management and control of risk deriving from the interaction of natural hazards with technological installations
Vulnerability assessment of process pipelines affected by flood events
No full textTechnological accidents can be triggered by the impact of natural events on industrial areas. Recent studies highlight the problem and the need to assess possible damage to process pipelines involved in flooding scenarios. The present study proposes for the first time a vulnerability model for this equipment category impacted by floods and suitable for the implementation in quantitative risk assessment (QRA) studies for the process industry. A mechanical model was first developed and compared against data available from the historical analysis of past accidents. The model is then applied to several geometries of process pipelines, with the aim of extending the range of conditions for failure prediction and developing a set of simplified correlations for the evaluation of pipelines failure. A simplified approach is finally adopted to develop the vulnerability model, in order to estimate the pipelines failure probability based on the analysis of critical design parameters and flooding conditions. In order to test the potentialities of the method, the vulnerability model proposed was implemented in the framework of a QRA and applied to an industrial case-study
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