Application of domino effect quantitative risk assessment to an extended industrial area

Escalation of primary accidental scenarios triggering a “domino effect” have caused extremely severe accidental events in the chemical and process industry. The identification of possible escalation events is required in the safety assessment of sites where relevant quantities of hazardous substances are stored or handled. In the European Union, “Seveso-II” Directive requires the assessment of on-site and off-site possible escalation scenarios in sites falling under the obligations of the Directive. In the present study, a methodology developed for the quantitative assessment of risk due to domino effect was applied to the analysis of an extended industrial area. Recently developed equipment damage probability models were applied for the identification of the final scenarios and for escalation probability assessment. The domino package of the Aripar-GIS software was used for risk recomposition. The results evidence that quantitative risk assessment of escalation hazard is of fundamental importance in order to identify critical equipment and to address prevention and protection actions.     

Quantitative risk assessment of domino effect in Natech scenarios triggered by lightning

Lightning strike is the natural event more frequency causing Natech accidents involving atmospheric storage tanks. Despite the resulting fires have usually limited severity and only local effects, domino effect may cause the escalation of these primary events, possibly affecting nearby pressurized storages and process equipment, thus resulting in relevant increase in the potential area impacted. A methodology was developed for the quantitative assessment of risk due to domino effects caused by Natech accidents triggered by lightning. A comprehensive procedure was obtained, tailoring lightning risk assessment to include probabilistic models for domino escalation based on probit approach and combinatorial analysis. The methodology was applied to a case-study to evidence the shift in risk figures due to domino effect and the credibility of the secondary domino scenarios. The results of the case-study show that an increase up to two orders of magnitude with respect to risk calculated for conventional scenarios is possible when considering lightning-induced Natech primary scenarios and their escalation.     

Quantitative assessment of domino and NaTech scenarios in complex industrial areas

Since the late 80s the application of quantitative risk assessment to the issue of land-use planning with respect to major accident hazards emerged as a topic to be addressed within the safety assessment of chemical and process plants. However, in the case of industrial clusters or complex industrial areas specific methodologies are needed to deal with high-impact low-probability (HILP) events. In the present study, innovative methodologies developed for the quantitative assessment of risk due to domino and NaTech scenarios are presented. In recent years a set of models for the calculation of equipment damage probability were developed. A specific effort was dedicated to the improvement of models for the calculation of equipment damage probability in these accident scenarios. In the present study, the application of these models to case-studies was analyzed. The results of the improved models obtained for NaTech quantitative assessment were compared to previous results in the literature. A specific innovative approach was developed to multi-level quantitative assessment of domino scenarios, and its potential was analyzed. The results were examined also evidencing the role and the progress with respect to the pioneering work started on these topics by Franco Foraboschi.     

DomPrevPlanning: User-friendly software for planning domino effects prevention

Chains of accidents, in literature generally referred to as domino effects, knock-on effects, cascade effects or escalation effects occur very infrequently but with disastrous consequences. There exist very few software packages to study such domino accidents in complex industrial areas and to forecast potential catastrophes caused by secondary order (involving a sequence of three installations submitted to two consecutive accidents), tertiary order or even higher order accidents. Moreover, available domino software focuses on risk assessment and on consequence assessment. None of these toolkits specifically addresses the prioritization of installation sequences in an industrial area in order to facilitate objective prevention decisions about domino effects. This paper describes the application of a new computer-automated tool designed to support decision-making on preventive and protective measures to alleviate domino effects in a complex surrounding of chemical installations. Using a holistic approach and thus looking at the entire industrial area as a whole, all sequences of three installations in the area are ranked according to their danger contribution to domino effects. An example of a cluster of chemical plants demonstrates the level of qualitative and quantitative input data required. The example is also used to explain the toolkit results, as well as the surplus value and the benefits for company safety managers and regulators.     

基于LOPA逻辑的罐区多米诺效应定量风险评估*

为了更好地降低化工企业罐区事故造成多米诺效应的风险,提出1种基于保护层分析（LOPA）的定量风险评估程序。首先,阐述基于保护层分析(LOPA)逻辑的多米诺定量风险评估流程,即引入包括可用性、有效性及3种逻辑门定义及量化的安全屏障定量评估;然后,利用LOPA的分析逻辑将安全屏障融入多米诺定量风险评估框架中;最后,选取2×2 000 m3苯乙烯罐区为对象,识别防火层与喷淋冷却系统2种安全屏障并开展基于LOPA逻辑的罐区多米诺效应定量风险评估,得出安全屏障能有效地降低多米诺事故发生频率及罐区个人风险的结论。研究结果表明:该分析方法可为化工企业开展多米诺效应定量风险评估提供参考。     

Reference criteria for the identification of accident scenarios in the framework of land use planning

Land use planning (LUP) around industrial sites at risk of major accidents requires the application of sound approaches in the selection of credible accident scenarios. In fact, the ‘technical’ phase of LUP is based on the identification and assessment of relevant accident scenarios. An improper choice of scenarios may critically affect both the ‘technical’ phase of risk assessment and the following ‘policy’ phase concerning decision making on land-use restrictions and/or licensing. The present study introduces a procedure aimed at the systematic identification of reference accident scenarios to be used in the gathering of technical data on potential major accidents, which is a necessary step for LUP around Seveso sites. Possible accident scenarios are generated by an improved version of the MIMAH methodology (Methodology for the Identification of Major Accident Hazards). The accident scenarios are then assessed for LUP relevance considering severity, frequency and time scale criteria. The influence of prevention and mitigation barriers is also taken into account. Two applications are used to demonstrate the proposed procedure. In both case-studies, the proposed methodology proved successful in producing consistent sets of reference scenarios.     

A fuzzy set analysis to estimate loss intensity following blast wave interaction with process equipment

Blast waves are able to produce structural damage to process equipment even at great distances from the source point of an explosion. A loss of containment may follow and, if hazardous substances are released, relevant secondary scenarios may be triggered, resulting in domino effects.The present study was focused on the assessment of the expected structural damage and of the associated intensity of loss of containment of process vessels loaded by blast waves. Hence, a knowledge-based fuzzy set analysis was used to assess the expected overall probability of occurrence of different damage states defined for several categories of process equipment items. The fuzzy approach was also used to obtain specific threshold values for the escalation sequences (domino effects), taking into account the hazard due to the expected secondary scenarios caused by the loss of containment following blast wave impact.     

Mechanism analysis and risk assessment of escalation scenario in chemical industry zones

Many major hazard installations (MHIs) are located in chemical industry zones and escalation effect may be triggered when the fire or explosion occurs on a MHI. To investigate the mechanism of the accident escalation, a systematic quantitative assessment methodology is proposed by the considering the feature and uncertainty of the escalation scenario. The main accident energy carriers of the escalation are heat radiation, overpressure of blast and fragments. The escalation probability, joint influence of the three energy carriers and risk characterization of the accident scenarios are carried out. By the new methodology, the escalation scenario in chemical industry zones can be analyzed and the risk escalation morphology is demonstrated by the simulation software. The visualized risk cloud figure gives a supplementary way to prevent the escalation scenario in chemical industry zones planning.     

质子交换膜燃料电池电站多米诺事故概率和风险研究*

为探究氢能电站火灾爆炸事故发展规律,采用多米诺效应对电站进行事故概率和风险研究,建立氢能电站多米诺效应定量风险分析模型。基于设备受损概率模型与多米诺理论基础,提出氢能电站多米诺效应概率计算方法,并将方法运用到实际案例,结合SAFETI软件对具体多米诺事故场景进行定量计算。研究结果表明:氢能电站易发生多米诺事故,考虑一级多米诺效应后人员潜在死亡概率增加56%。研究结果可为制定氢能电站安全防控措施以及降低火灾爆炸事故对人员和设备的危害提供依据。     

Method for quantitative assessment of the domino effect in industrial sites

Accidents caused by the domino effect are the most destructive accidents related to industrial sites. The most typical primary incidents for a domino effect sequence are explosions (57%), followed by fires (43%) (Abdolhamidzadeh et al., 2010). These former can generate three escalation vectors (heat load, overpressure, and fragments), and may affect the surrounding equipments and/or facilities. If the affected targets are damaged, they may also explode and generate other threats to other surrounding facilities and so on. These chains of accidents may lead to catastrophic consequences and may affect not only the industrial sites, but also people, environment and economy. This paper presents a methodology for quantitative assessment of domino effects caused by fire and explosion on storage areas. The individual and societal risks are also estimated.     

基于多米诺效应的定量风险评价研究

多米诺效应是引发化工重大事故的主要原因之一.本文综合国内外的研究成果,对火灾热辐射、冲击波超压等造成的多米诺效应进行了深入分析,建立基于多米诺效应的定量风险评价模型,其中包括了评价流程、传播概率、阈值距离计算、多米诺效应对事故频率的影响及后果分析的内容.最后利用Matlab7.1计算平台,以汽油储罐进行实例分析,结果表明该方法是一种适用于多米诺效应定量评价的良好方法,能够比较科学、有效的对危险单元进行风险评价,使重大事故风险评价更切合实际,为政府监管部门和化工企业进行事故的控制和预防提供决策技术.     

Assessment of risks posed by chemical industries—application of a new computer automated tool maxcred-III

The paper describes the application of a new computer automated tool, developed by us, in the risk analysis of a typical chemical industry engaged in the manufacture of linear alkyl benzene. Using the tool—a comprehensive software package maxcred-III (MAXimum CREDible accident analysis)—nine different scenarios, one for each storage unit, have been studied. It is observed that the accident scenario for chlorine (instantaneous release followed by dispersion) leads to the largest area-under-lethal-impact, while the accident scenario for propylene (CVCE followed by fireball) forecasts the most intense damage per unit area. The accidents involving propylene, benzene, and fuel oil have a high possibility of causing domino/secondary accidents as their destructive impacts (shock waves, heat load) would envelope other storage and process units.Besides demonstrating the utilizability of maxcred-III, this study also focuses attention on the need to bestow greater effort towards risk assessment/crisis management. The authors hope that the study will highlight the severity of the risk posed by the industry and thus generate safety consciousness among plant managers. The study may also help in developing accident-prevention strategies and the installation of damage control devices.     

Resilience-based optimal firefighting to prevent domino effects in process plants

Domino effects triggered by fire can cause extremely severe damages to the chemical and process plants. In the need of a more effective prevention of fire domino effects, the present study focuses on firefighting which has received less attention compared to passive and active fire protection systems. Considering both the vulnerability and recoverability phases during fire domino effects, we have introduced a methodology for optimal identification of firefighting strategies so as to increase the resiliency of process plants in dealing with fire escalation scenarios. The area above the resilience curve (AARC), which is equal to the accumulation of loss of resilience over time, was considered as the metric to identify the optimal firefighting strategies. In other words, the strategy leading to the lowest AARC can be selected as the optimal strategy from a resiliency perspective.     

基于RBI与多米诺效应的输气站场设备定量风险评价

针对目前输气站场设备风险评价方法仅以单个设备为评价对象,并未考虑设备间相互影响的特点,提出将多米诺效应分析引入输气站场设备风险评价当中,再结合RBI(基于风险检测方法)对输气站场设备进行定量风险评价。首先,计算所评价设备的失效概率与危险指数,得到设备固有风险;然后对设备的多米诺效应风险进行计算;最后,得到设备总风险。实例分析表明,考虑多米诺效应风险后,站场单个设备的风险要明显增大。     

ExSys-LOPA for the chemical process industry

The chemical process industries are characterized by the use, processing, and storage of large amounts of dangerous chemical substances and/or energy. Among different missions of chemical plants there are two very important ones, which: 1. provide a safe work environment, 2. fully protect the environment. These important missions can be achieved only by design of adequate safeguards for identified process hazards. Layer of Protection Analysis (LOPA) can successfully answer this question. This technique is a simplified process of quantitative risk assessment, using the order of magnitude categories for initiating cause frequency, consequence severity, and the likelihood of failure of independent protection layers to analyze and assess the risk of particular accident scenarios. LOPA requires application of qualitative hazard evaluation methods to identify accident scenarios, including initiating causes and appropriate safeguards. This can be well fulfilled, e.g., by HAZOP Studies or What-If Analysis. However, those techniques require extensive experience, efforts by teams of experts as well as significant time commitments, especially for complex chemical process units. In order to simplify that process, this paper presents another strategy that is a combination of an expert system for accident scenario identification with subsequent application of LOPA. The concept is called ExSys-LOPA, which employs, prepared in advance, values from engineering databases for identification of loss events specific to the selected target process and subsequently a accident scenario barrier model developed as an input for LOPA. Such consistent rules for the identification of accident scenarios to be analyzed can facilitate and expedite the analysis and thereby incorporate many more scenarios and analyze those for adequacy of the safeguards. An associated computer program is under development. The proposed technique supports and extends the Layer of Protection Analysis application, especially for safety assurance assessment of risk-based determination for the process industries. A case study concerning HF alkylation plant illustrates the proposed method.     

基于蒙特卡洛模拟的多米诺事故风险量化管理*

为降低危化品相关的化工事故造成的人员伤亡和财产损失，以化工多米诺事故为研究对象，探讨由初始事故引发1个或多个次生事故的连锁反应机理与风险评估方法。提出应用蒙特卡洛模拟对多米诺事故风险进行动态量化的方法，梳理化工多米诺事故风险的识别、分析、评定、处理全周期管理流程，并以1个天然气压气站为案例，验证基于蒙卡模拟的化工多米诺事故风险量化方法的有效性。结果表明:该方法可以更准确地对化工多米诺事故风险进行定量评估。多米诺事故风险全周期管理流程的梳理能够有效指导化工企业开展安全管理、事故预防等工作。     

化工储罐区池火灾多米诺效应风险评估

化工储罐区储罐数量较多且集中,一旦发生事故很可能诱发多米诺效应造成灾难性的后果。在分析池火灾多米诺效应作用模式的基础上,建立了池火灾多米诺效应风险评估模型,并对某化工储罐区进行了实例计算,分析了单一储罐池火灾事故引发其他储罐池火灾的风险。分析结果表明,池火灾是诱发化工储罐多米诺事故的重要因素,且会造成风险的显著增加,但并非所有的池火灾事故都会诱发多米诺效应。此外,将多米诺效应评价方法应用于化工储罐池火灾事故风险评估中可有效地预测次生事故的发生概率和后果,从而提出针对性措施。     

基于多米诺效应的油品储罐区个人风险研究

介绍了多米诺效应的基本原理和多米诺事故发生的概率分析方法。提出在一定条件下进行储罐区风险评价时，多米诺效应对个人风险值的影响不容忽视，并给出了考虑多米诺效应的个人风险计算方法。最后利用开发的个人风险计算软件通过分析计算，给出了某储罐区的个人风险等值线分布图。结果表明，该罐区正北方向相邻的一劳动密集型工厂需搬迁，或采取相应安全保护措施降低风险。该方法考虑了多米诺效应对装置事故发生概率的影响，能提高个人风险计算结果的真实性与准确性。     

Project risk identification and assessment simultaneously using multi-attribute group decision making technique

The identification and assessment of project risks among potential risks can be considered a multi-attribute group decision making (MAGDM) problem including both quantitative and qualitative criteria. We extend the concept of safety to risk identification and assessment; this is to emphasize that the focus should not only be on the time and cost criteria, but also on the health, safety and environment (HSE) criterion. Conventional approaches to risk identification and risk assessment separately tend to be less effective in dealing with the imprecise of the risk assessment individually. The aim of this paper is to present a new methodology for identifying and assessing risks simultaneously by applying MAGDM technique. This paper includes a new procedure for classifying potential risks which it is named potential risk breakdown structure (PRBS) based on project work breakdown structure (WBS). Nominal group technique (NGT) is utilized for gathering potential risks. Obtained results have been applied in gas refinery plant construction successfully.