Dynamic approach to risk management: Application to the Hoeganaes metal dust accidents

Several major accidents caused by metal dusts were recorded in the past few years. For instance, in 2011, three accidents caused by iron dust killed five workers at the Hoeganaes Corp. facility in Gallatin, Tennessee (USA). In order to prevent such accidents, a dynamic approach to risk management was defined in this study. The method is able to take into account new risk notions and early warnings and to systematically update the related risk. It may be applied not only in the design phase of a system, but also throughout the system lifetime as a support to a more precise and robust decision making process. The synergy of two specific techniques for hazard identification and risk assessment was obtained: the Dynamic Procedure for Atypical Scenarios Identification (DyPASI) and the Dynamic Risk Assessment (DRA) methods. To demonstrate its effectiveness, this approach was applied to the analysis of Gallatin metal dust accidents. The application allowed collecting a number of risk notions related to the plant, equipment and materials used. The analysis of risk notions by means of this dynamic approach could have led to enhanced hazard identification and dynamic real-time risk assessment. However, the approach described is effective only if associated to a proper safety culture, in order to produce an appropriate and robust decision making response to emerging risk issues.     

Addressing emerging risks using carbon capture and storage as an example

The European iNTeg-Risk project is a large-scale integrated project aimed at improving the management of emerging risks related to new technologies in European industry. The project aims to build a new management paradigm for emerging risks as a set of principles supported by a common language, agreed tools and methods, and key performance indicators, all integrated into a single framework. It is using a number of Emerging Risk Representative Applications (ERRAs), or case studies, to inform the development of the framework; one of which concerns the carbon capture and storage (CCS) process.This paper describes the iNTeg-Risk CCS ERRA. Relevant hazards and properties of carbon dioxide are described and the emerging risks from CCS are discussed. Three new tools have been developed or trialled within the ERRA. These are: the DyPASI methodology for taking account of atypical (not usually identified) events during hazard identification; a methodology for including the time dimension in a risk assessment; and life-cycle approaches for risk management and communication. For CCS, the risk assessment needs to include both short-term potential accidents from capture, transport or injection, as well as very long-term risks from storage. Knowledge gaps which are generic to emerging risks are also identified.     

Surface installations intended for Carbon Capture and Sequestration: Atypical accident scenarios and their identification

With the advent of Carbon Capture and Sequestration (CCS) technology the extent of CO₂ handling is set to increase dramatically. However, lack of substantial operational experience in such a novel process can lead to significant difficulties in identifying the associated hazards. This field may be characterized by atypical accident scenarios, i.e. scenarios not captured by common HAZard IDentification (HAZID) techniques because of omissions, errors or lack of knowledge. Recent atypical events evidence that consequences may exceed by far those of worst-case reference scenarios. Identification of atypical scenarios related to CCS is a challenge, considering also the public concern that this technology raises. This study focuses on new and emerging technologies of carbon capture and transport. A HAZID analysis was carried out by means of two different approaches (‘top-down’ and ‘DyPASI’). This allowed not only for a double check of results, but also for the comparative assessment of the methodologies and of their applicability. A general overview of the accident scenarios related to these technologies was given. No absolute showstoppers were found. Rather, a number of potential hazards were identified which will require the adoption of safe design principles to eliminate, prevent, control or mitigate them. Some possible safety barriers required for implementation were identified as a starting point in this process.     

Supporting the selection of process and plant design options by Inherent Safety KPIs

Effective support of inherent safety implementation in process design requires a quantitative metric for monitoring and communicating the expected safety performance of alternative design options. The Inherent Safety Key Performance Indicators (IS-KPIs) methodology was developed to provide both a flexible procedure for the identification of the hazards, and a sound consequence-based quantification of the safety performance. The integration of different hazard identification techniques yields the relevant accident scenarios for each unit in the plant. The calculation of credible damage distances by consolidate consequence simulation models provides a sound basis for the definition of the KPIs based on worst case effects. Specific indicators were devoted to hazards from external actions, as natural events and intentional malicious acts. The methodology was demonstrated by the comparison of alternative technological options for LNG regasification. The application evidenced the potential of the IS-KPI method in pinpointing the critical issues related to each alternative configuration.     

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.     

Application of dynamic risk analysis in offshore drilling processes

Process safety is the common global language used to communicate the strategies of hazard identification, risk assessment and safety management. Process safety is identified as an integral part of process development and focuses on preventing and mitigating major process accidents such as fires, explosions, and toxic releases in process industries. Accident probability estimation is the most vital step to all quantitative risk assessment methods. Drilling process for oil is a hazardous operation and hence safety is one of the major concerns and is often measured in terms of risk. Dynamic risk assessment method is meant to reassess risk in terms of updating initial failure probabilities of events and safety barriers, as new information are made available during a specific operation. In this study, a Bayesian network model is developed to represent a well kick scenario. The concept of dynamic environment is incorporated by feeding the real-time failure probability values (observed at different time intervals) of safety barriers to the Bayesian network in order to obtain the corresponding time-dependent variations in kick consequences. This study reveals the importance of real-time monitoring of safety barrier performances and quantitatively shows the effect of deterioration of barrier performance on kick consequence probabilities. The Macondo blowout incident is used to demonstrate how early warnings in barrier probability variations could have been observed and adequately managed to prevent escalation to severe consequences.     

Qualitative Assessment for Inherently Safer Design (QAISD) at preliminary design stage

Conventional hazard evaluation techniques such as what-if checklist and hazard and operability (HAZOP) studies are often used to recognise potential hazards and recommend possible solutions. They are used to reduce any potential incidents in the process plant to as low as reasonably practicable (ALARP) level. Nevertheless, the suggested risk reduction alternatives merely focus on added passive and active safety systems rather than preventing or minimising the inherent hazards at source through application of inherently safer design (ISD) concept. One of the attributed reasons could be the shortage of techniques or tools to support implementation of the concept. Thus, this paper proposes a qualitative methodology that integrates ISD concept with hazard review technique to identify inherent hazards and generate ISD options at early stage of design as proactive measures to produce inherently safer plant. A modified theory of inventive problem solving (TRIZ) hazard review method is used in this work to identify inherent hazards, whereby an extended inherent safety heuristics tool is developed based on established ISD principles to create potential ISD options. The developed method namely Qualitative Assessment for Inherently Safer Design (QAISD) could be applied during preliminary design stage and the information required to apply the method would be based on common process and safety database of the studied process. However, user experiences and understanding of inherent safety concept are crucial for effective utilisation of the QAISD. This qualitative methodology is applied to a typical batch reactor of toluene nitration as a case study. The results show several ISD strategies that could be considered at early stage of design in order to prevent and minimise the potential of thermal runaway in the nitration process.     

Safety analysis and risk assessment of a Micro-GtL Plant

Laboratory hydrogen generators, medical oxygen, and micro-breweries are examples of modular and micro technologies that are commercial successes. Researchers, patients, and unskilled workers operate these facilities but more complex processes require highly qualified personnel to ensure they operate safely. Modular-micro processes in isolated locations meet economic objectives when operated remotely thereby minimizing labor costs. Mitigating the risk requires a comprehensive hazards analysis with advanced control systems particularly for explosive and toxic compounds. Here, we propose a method called Failure Mode Risk Decision (FMRD) to review the inherent hazards of a micro-refinery unit (MRU) that converts flared and wasted natural gas to long chain hydrocarbons. This approach combines the Process Flow Failure Mode (PFFM) methodology as a systematic and reliable technique with a novel numerical risk assessment to improve the analytical evaluation of hazardous conditions. The objective is to combine causes and consequences in a single metric, where scaled probability of evident causes and severity of consequences are used to derive a risk level measure. With the proposed metric, the magnitude of a potential hazard is directly correlated with the risk level. This mechanism identifies extra risk scenarios compared to the classical hazard analysis method and provides a straightforward comprehensive numerical assessment to represent the inherent and residual risks to facilitate justifying the hazardous scenarios. Accordingly, we design a safety loop and supply all the required facilities to remove the potential risks at the process plant. Not only the proposed methodology clarifies the risks of the MRU presented in this study, but can be extended to review the hazards of other chemical process plants.     

A blended hazard identification methodology to support process diagnosis

A novel hazard identification methodology applied to process systems is presented in this paper. This blended hazard identification (BLHAZID) methodology blends two different types of HAZID methods: the function-driven and component-driven approach. The BLHAZID method is based on a conceptual framework called the Functional Systems Framework, which describes structure–function–goal relationships in process systems.The goals of the BLHAZID methodology are to generate outcomes that contain a high coverage of hazards, describe detailed failure causality in process systems and express this knowledge in a structured form for effective reused in subsequent applications, such as fault diagnosis, operator training, design reviews, fault and event tree construction and hazard updates to satisfy major hazard facility requirements.Both the BLHAZID methodology and the Functional Systems Framework were developed with involvement and advice from two major industrial partners. An industrial case study of a benzene saturation unit is presented to illustrate how the BLHAZID methodology operates in practice.     

Reducing unknown risk: The safety engineers’ new horizon

A significant gap exists between accident scenarios as foreseen by company safety management systems and actual scenarios observed in major accidents.The mere fact that this gap exists is pointing at flawed risk assessments, is leaving hazards unmitigated, threatening worker safety, putting the environment at risk and endangering company continuity. This scoping review gathers perspectives reported in scientific literature about how to address these problems.Safety managers and regulators, attempting to reduce and eventually close this gap, not only encounter the pitfalls of poor safety studies, but also the acceptance of ‘unknown risk’ as a phenomenon, companies being numbed by inadequate process safety indicators, unsettled debates between paradigms on improving process safety, and inflexible recording systems in a dynamic industrial environment.The immediacy of the stagnating long term downward major accident rate trend in the Netherlands underlines the need to address these pitfalls. A method to identify and systematically reduce unknown risks is proposed. The main conclusion is that safety management can never be ready with hazard identification and risk assessment.     

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.     

Mapping human vulnerability and risk due to chemical accidents

Chemical accidents in the vicinity of densely populated areas can cause colossal damage. Close proximity of chemical facilities to the general public has been identified as a major issue for increased human exposure in 43% of the accidents investigated by the U.S. Chemical Safety Board (CSB). This emphasises the need for incorporating societal factors in risk assessment to plan actions in order to minimise exposure during accidents. The purpose of this research is to develop a model for the assessment of human vulnerability and risk due to chemical accidents. A GIS based methodology is proposed which uses computer aided hazard modelling tools and technical guidelines to model accidents and assesses population vulnerability. The population vulnerability is determined based on a set of societal indicators derived from relevant research work, expert opinions and suggestions by World Bank. Risk is defined as the probable magnitude of harm to humans and dependent on both the degrees of hazard and vulnerability. A case study is carried out by applying the methodology to Meghnaghat Industrial Area in Bangladesh. Accident scenarios are built and hazard modelling software ALOHA is used to spatially display accident footprints. Vulnerability of population is assessed using data from Bangladesh Bureau of Statistics (BBS) and field survey. The hazard footprints and vulnerability map are superimposed using mapping software ArcGIS to generate a composite risk map. The risk map is used to assess existing land use and recommendations are made for future land use planning. The composite risk map is expected to be of help for effective community response, emergency response planning and allocation of medical and support services during emergencies.     

Building Safety indicators: Part 2 – Application,practices and results

Petroleum exploration and production in the Barents Sea is a controversial topic. The Goliat field outside the northern coast of Norway will be the first offshore oil development in this region, with planned production start in 2013–2014. Avoiding major accidents at Goliat is critical; not only to reduce the risks to human lives and the environment, but also to gain political acceptance. Providing early warnings of major accidents for Goliat is one of the main objectives of the research project ‘Building Safety’. The objective of this paper is to describe the development of early warnings in the form of indicators. In addition, the paper includes an overview of current status of early warnings of accidents in other major hazard industries; the nuclear power industry, the chemical process industry, and aviation. Experiences from these industries, including lessons learned from recent major accidents, have been used as important input to the development of early warning indicators.     

基于危险的事故场景及其形式化描述

事故场景的鉴别是复杂装备系统安全风险分析的基础,其完备性直接影响风险评估的有效性,因为任何事故场景的遗漏即意味着设计上可能存在潜在的事故隐患。提出从鉴别系统危险出发。建立危险与其原因(关联引发事件)、事件与系统要素以及系统各要素之间的映射关系,通过对这些关系的运算来获取事故场景的新方法并给出其形式化表述,以期在理论上确保事故场景鉴别的完备性。     

设计初期化工过程本质安全化设计策略

该文提出了一种在设计初期进行化工过程本质安全化设计的策略。首先进行危险物质与危险能量两类共计11种危险类型的危险辨识。针对辨识出的危险类型,通过与相应的临界条件比较进行快速的危险评价,对于不可接受的危险必须采取本质安全化措施,可接受的危险可有选择性地进行本质安全化设计。在设计初期可以使用的本质安全化原则主要是消除、最小化、替代和缓和,针对11种危险类型可以应用不同的本质安全化设计模型,以使实际进行本质安全化设计时更加简单与快捷。该文把提出的本质安全化设计策略应用到一个甲苯硝化制硝基甲苯的工艺,形成了多种本质安全化措施,可以用来在设计初期消除或减少危险。     

Scenario identification and evaluation for layers of protection analysis

The identification and screening of scenarios has been identified as a source of variation in Layers of Protection Analysis (LOPA). Often the experience of the analyst is a significant factor in determining what scenarios are evaluated and the worst credible consequences. This paper presents a simplified chemical process risk analysis that is effective in providing a semi-quantitative measure of consequence that may include human harm and is independent of the analyst. This process may be used in evaluation of Management of Change, inherently safer design decisions for capital projects and LOPA re-validation. Conditional and relational logic may be captured with the use of simple spreadsheets to further improve overall efficiency. For example, this method minimizes the overall time required for scenario development and re-validation relative to Hazard and Operability studies (HAZOP).The technique simplifies established models used by engineers engaged in the operation or design of a chemical manufacturing facility without special software or training. The results of this technique are realistic and may be directly compared with corporate or regulatory guidelines for risk of fatality or injury. At each step in the risk analysis process, more detailed or sophisticated methods may be used to refine the technique. Furthermore, results from any step may indicate that the hazard from a specific scenario case is not sufficient to continue with subsequent analysis steps.     

Quantitative assessment of domino scenarios by a GIS-based software tool

A software procedure was developed for the quantitative assessment of domino effect. The procedure was based on a systematic methodology for the identification of domino scenarios and for the assessment of consequences and expected frequencies of the escalation events. A geographical information system (GIS) platform was interfaced to the domino assessment software. The implementation of plant lay-out data to the GIS allowed the automatic identification of the possible targets of escalation effects by the software procedure, and a straightforward calculation of the contribution to individual and societal risk indexes caused by the possible domino scenarios. The procedure was applied to the analysis of several case-studies based on actual plant lay-outs. The results evidenced that the approach allows the quantitative assessment of risk caused by escalation events with a limited additional effort with respect to that required by a conventional QRA. The use of a GIS-based software was a key element in the limitation of the effort required for the quantitative assessment of domino scenarios. Moreover, the results of the case-studies pointed out that the estimation of risk increase due to domino events is an important tool for an effective assessment and control of industrial risk in chemical and process plants.     

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 methodology for evaluation and monitoring of recurring hazards in underground coal mining

This study provides a methodology for evaluation and monitoring of recurring hazards in underground coal mining. An important measure in this regard may be the ‘time between occurrences’ (TBO) of hazards that can be modeled in the similar fashion of ‘time between failures’ (TBF) data modeling which is practiced in reliability study. Typically, time between accidents is modeled in safety study. This study is therefore new in two counts: (i) statistically modeling hazard occurrences based on inspection reports and (ii) monitoring of safety status based on control charting of hazard occurrences. The methodology includes Weibull-distribution based hazard rate functions, Poisson-distribution based cumulative risk functions, and Weibull-distribution based control charts. The new methodology is applied to an underground coal mining worksystem and the results are discussed. The case study results show that hazards related to machinery, ground-fall, housekeeping, roadways, and materials are more frequently occurring. It is recommended that in addition to planned inspections for identification of hazards, a control chart based hazard mitigation scheme should be employed at the mine sections for better monitoring and control of hazards.     

煤矿危险源风险预警与控制的研究

根据现代安全管理的理论与方法,结合煤矿人-机-环境特点和不同煤矿事故的发生机理,对煤矿危险源风险预警和控制的基本理论和方法进行了探讨,提出了基于危险源的煤矿风险预警与控制的一般流程,给出煤矿危险源辨识、风险评价、监控和预警的方法,为煤矿安全管理信息系统提供理论基础。