Improving PHA/LOPA by consistent consequence severity estimation

Most risk analysis methods rely on a qualitative judgment of consequence severity, regardless of the analysis rigor applied to the estimation of hazardous event frequency. Since the risk analysis is dependent on the estimated frequency and consequence severity of the hazardous event, the error associated with the consequence severity estimate directly impacts the estimated risk and ultimately the risk reduction requirements. Overstatement of the consequence severity creates excessive risk reduction requirements. Understatement results in inadequate risk reduction.Consistency in the consequence severity estimate can be substantially improved by implementing consequence estimation tools that assist PHA/LOPA team members in understanding the flammability, explosivity, or toxicity of process chemical releases. This paper provides justification for developing semi-quantitative look-up tables to support the team assessment of consequence severity. Just as the frequency and risk reduction tables have greatly improved consistency in the estimate of the hazardous event frequency, consequence severity tables can significantly increase confidence in the severity estimate.     

Developing a chaotic pattern of dynamic risk definition for solving hazardous material routing-locating problem

In the case of determining routes and locations for constructing distribution centers on hazardous materials (Hazmat) transportation, risk and cost are considered as the main attributes for developing mathematical models. Since, Hazmat transport risk may be defined as a chaotic factor, using dynamic risk changes the selected routes and optimized locations for constructing distribution centers.In the present paper, an iterative procedure has been proposed to determine the best routes and optimized locations of distribution centers for transporting hazardous materials based on the concept of chaos theory in which hazmat transport risk is defined as a dynamic variable. A mathematical model has been developed for solving Hazmat routing and locating problems, simultaneously. Daily transport risk, defined as a chaotic variable, is iteratively updated using one-dimensional logistic map equation over the time period (year). An experimental road network, consists of eighty nine nodes and one hundred and three two-way edges, has been selected for analytical process and model validation. Results revealed that although different amounts of risk and cost priorities change optimized locations of distribution centers and their associated supplies, but the most frequent set of optimized centers remains independent. Therefore, the proposed procedure is capable to determine the best routes and optimized locations for distributing hazardous materials. While risk is iteratively updated over a specific time period, results show that the main property of chaos theory known as dependency upon initial condition would not be a serious concern for decision makers who are dealing with Hazmat management.     

Assessment of hazardous material risks for rail yard safety

This paper illustrates the application of quantitative risk assessment in a rail yard where tank cars of hazardous materials are received and stored. The assessment was conducted in response to community concerns about the safety of a proposed yard expansion. Six different chemicals are involved. For each one, the average monthly volume and the hazard of most concern are specified. We use an event tree populated with empirical data to compute the probability of a major spill in each case and we estimate the corresponding critical impact distances using available modeling tools. We find that for some of the chemicals, the relative increases in risk are appreciable, but that in all cases, the absolute levels of risk remain low. Then we identify some ways in which such an analysis can be extended and discuss the potential difficulties associated with these extensions.     

Risk informed optimization of a hazardous material multi-periodic transportation model

This paper presents a systematic framework toward the development of a Transportation Model for Hazardous Materials (HazMat). In practice, the proposed modeling framework is realized through an appropriate generalization of the traditional transportation network problem in the presence of safety constraints that need to be satisfied. The objective is to minimize transportation cost while reducing risks at the desired levels.In particular, the present research study identifies and evaluates different risk factors that influence the HazMat transportation network. Next, the transportation model is depicted graphically using nodes and arcs and optimal conditions are identified by solving the associated minimum cost flow network problem. The results show safety levels that help making informed decisions on choosing the optimal transportation configuration for hazardous material shipments.Within the proposed methodological context, appropriately parameterized simulation studies elucidate the effects of occurrence probabilities of the different risk events on transportation cost. Furthermore, as the appropriate management decisions must consider the effect of actions in one time period on future periods, the proposed model is structured as a multi-periodic model.Finally, the proposed methodological approach is employed to demonstrate the utility of proper analytical tools in decision making and particularly in ensuring that scientifically informed safety procedures are in place while transporting goods that can be potentially proven dangerous to the public and the surroundings.     

LNG as a potential alternative fuel - Safety and security of storage facilities

The aim of this article is to summarize the safety and security aspects of storing of Liquefied Natural Gas (LNG) as a potential alternative fuel. The contribution deals with possible scenarios of accidents associated with LNG storage facilities and with a methodology for the assessment of vulnerability of such facilities. The protection of LNG storage facilities as element of critical infrastructure should also be a matter of interest to the state. The study presents the results of determination of hazardous zones around LNG facilities in the event of various sorts of release. For calculations, the programs ALOHA, EFFECTS and TerEx were used and results obtained were compared. Scenarios modelled within this study represent a possible approach to the preliminary assessment of risk that should be verified by more detailed modelling (CFD). These scenarios can also be used for a quick estimation of areas endangered by an incident or accident. The results of modelling of the hazardous zones contribute to a reduction in risk of major accidents associated with these potential alternative energy sources.     

A cascaded fuzzy-LOPA risk assessment model applied in natural gas industry

Natural gas plants demand high amount of energy provided through immense fuel gas units that may suffer risk hazards. Implementing a safety management system is the most efficient way of allocating resources for safety. This paper adopts The Layer of Protection Analysis (LOPA) risk Management associated with Fuzzy Logic methodology to prevent or limit industrial accidents. We provide an innovative cascaded fuzzy-LOPA model for certain hazardous scenarios and at different frequencies of occurrence. The introduced model is tested at moderate and high risk levels controlled in its practical limits through the use of Safety Integrity Functions (SIF). Obtained results show how this fuzzy-LOPA achieves better results to maintain the Safety Integrity Level (SIL) rating to acceptable limits.     

Impact analysis of multi-sensor layout on the source term estimation of hazardous gas leakage

In chemical industry, sensors are used to monitor the leakage and emission of hazardous materials that are used for hazard warning and risk assessment to ensure safety production. The traditional sensor layout designs the scheme at single-layer, and thus causes large deviations in the estimated height and accuracy of source term estimation (STE). In this study, a dual-layer layout scheme for sensors is proposed. The numerical experiments verify that the improved schemes with an equal number of sensors, as well as detection errors, are beneficial to the accuracy of the STE results. The influence of the heights of the sensors and leak source on the results of STE is studied. Results show that the dual-layer sensor scheme with adjacent intervals at high places in the potential search space is highly favorable to locate the leak, and the scheme arranged near the ground is conducive for improving the estimation accuracy of source intensity. This study also compares the STE results of computational fluid dynamics (CFD) simulated scenarios under different sensor schemes and verifies the effectiveness of the proposed dual-layer sensor deployment scheme with adjacent intervals under turbulence condition.     

Simulation of scenario characteristics of LPG tank explosion accident and its contribution to emergency planning: A case study

Leakage and explosion of hazardous chemicals during road transportation can cause serious building damage and casualties, and adoption of highly-efficient emergency rescue measures plays a critical role in reducing accidental hazards. Considering a liquefied petroleum gas (LPG) transport tanker explosion accident that occurred in Wenling, Zhejiang Province, China on June 13, 2020 as example, this study proposes a risk assessment framework. This framework recreates the leakage and explosion of the accident process using FLACS v10.9, suggests plans for evacuation, describes the rescue areas of different levels, and explores the influence of environmental factors on the evacuation and rescue areas. The results show that simulated and predicted distributions of fuel vapour cloud concentration and explosion overpressure can provide a reference basis for rapid rescue activities; the characterization of the dynamic effects of wind speed, wind direction, and temperature with respect to the evacuation and rescue areas can be used as theoretical support for on-site adjustment of rescue forces. The role of obstacles can prevent the expansion of the evacuation areas under low wind-speed conditions, and the presence of highly congested obstacles determines the level of the rescue area. The results obtained are important for the risk analysis and the development of emergency rescue measures in case of explosion accidents associated with transportation of hazardous chemicals on high-hazard and high-sensitive road sections.     

基于风险的有害物品运输的线路选择分析

为了选择风险尽量小的线路来运输有害物品,减小在运输此类物质时对道路两侧人口带来的风险,通过比较分析,在选择Gaussian模型基础上,将有害物品泄漏后果的概率函数法与人口的风险描述方法相结合,并根据运输中对风险标准的不同要求,结合实际运输过程中可供选择的不同线路的实际情况,得到一次运输中选择不同线路时所产生的相异风险值,从而为有害物品运输中如何通过最小化运输过程中的人口风险来选择线路提供了依据。通过算例分析,得到的结果与使用其它分析性工具得到的结论一致,但结果精确性更高,表明研究结果有很好的实用性,能对实际生产中避免因有害物品运输而带来重大事故有一定指导作用。     

Main differences on European regulations in the frame of the Seveso Directive

Since the first Seveso Directive was issued 25 years ago, each Member State of the European Union developed own regulations to enforce its application. The lack of a common approach generated differences between Member States, or even between regions within a Member State, which in practical terms caused that establishments falling under the field of application of the Seveso Directive face a different level of requirements. This situation causes significantly different impact on social, technical and financial aspects.Factors like industrial background, accidental history, actual land use, social attitude towards risk, economical and political structures play an important role in how the decisions about hazardous activities are perceived and handled.Answering the question: “Is there a right methodology for the assessment of the risk of major accidents?” may be sterile or impossible. Many tools are appropriate and the main concern is to use them properly. Technically, the causes and consequences of, e.g., a fire in a port in Spain on the Mediterranean Sea or in the port of Basel (Switzerland) in the Rhine River could be assessed using the same methods and criteria, but this is not usually the case.This paper shows, with practical examples, the differences existing while applying different regulations in the field of prevention of major accidents and the potential effects that these differences may generate regarding the definition and management of emergency plans outside establishments.If the existing unequal situation is not faced, the comparative disagreements between Member States will prevail. Therefore, the application of the Seveso Directive will generate a different impact on the society, operators and regulators, and may become a factor which may cause a risk transfer between Member States. Efforts should be addressed to harmonize criteria in this subject.     

A transportation network assessment tool for hazardous material cargo routing: Weighing exposure health risks,proximity to vulnerable areas,delay costs and trucking expenses

The inherent risks associated with accidental releases of hazardous materials during transport have drawn attention and concerns in the recent decades. The aim of this study is to propose a tool for evaluation and comparison of the transportation networks which can be used to assess the routing options between origins and destinations of the cargos for their suitability for transporting hazardous material cargos by tanker trucks and to identify routes which provide lower accidental release risks, lower public exposure risks, and offer economical benefits. Each route segment of transportation networks were evaluated using specific criteria which included health risk and cost of delay in case of an accidental release of materials, trucking cost and proximity to vulnerable areas. Since, the health impact of hazardous materials differ depending on the characteristics of the material being transported as well as release quantities and atmospheric conditions; this paper aimed in providing a tool that can be used to estimate the impact radius (for health risks) after accidental release of hazardous materials by taking into account different atmospheric conditions based on the meteorological data and solar elevation angle. The Gaussian air dispersion model paired with ArcGIS using Python programming were employed to estimate the health risk impact zones by considering the meteorological data, and accordingly to analyze road segments for cost impacts (delay and trucking costs), and the proximity to vulnerable areas. The route assessment tool was demonstrated with a case study. The results of this study can efficiently aid decision makers for transportation of hazardous materials.     

An Analysis of the Cumulative Uncertainty Associated with a Quantitative Consequence Assessment of a Major Accident

The accident consequence estimation for a particular hazardous installation consists of source term estimation, dispersion simulation, and an assessment of the effects on the people, buildings and equipment. In the article the typical range of the uncertainty of each separate step is assessed and then combined and analysed with the view to understand their cumulative influence on the uncertainty surrounding the resulting consequence value. Certain assumptions and a simple error calculation formula have been applied to produce the analysis of influence of individual error estimates on the final consequence assessment. The data used are partially taken from past benchmarking exercises conducted by the Major Accident Hazards Bureau (MAHB) of the European Commission's Joint Research Centre, and partially from literature sources. The methodology for combining the separate uncertainty values together and the results of the analysis of the combined influence of the uncertainties associated with each step are described.     

Accidents: A discrepancy between indicators and facts!

Despite, the overwhelming amount of currently available safety management systems (and accompanying tools) accidents with hazardous substances still occur every now and then in the process industries.In this paper a large number of recently occurred accidents in the process industries are analysed showing that reoccurring disruptions during daily operation were present in the causal path of these accidents. The reoccurring disruptions can be seen as pre-warning signals. Their existence forms a gap with the common proactive safety indicators. This gap exists of information, already present and available in daily operation, of which it is UNKNOWN (to the local assessor) that it may lead to unsafe situations/accidents, e.g. maintenance backlogs, quality reports, etc.It is argued that these reoccurring events should be considered to be included in the safety indicators after assessment by an extended body of knowledge, because these events seem to become increasingly important regarding the prevention of accidents that still occur nowadays.     

Risk analysis of deepwater drilling operations using Bayesian network

Deepwater drilling is one of the high-risk operations in the oil and gas sector due to large uncertainties and extreme operating conditions. In the last few decades Managed Pressure Drilling Operations (MPD) and Underbalanced Drilling (UBD) have become increasingly used as alternatives to conventional drilling operations such as Overbalanced Drilling (OVD) technology. These newer techniques provide several advantages however the blowout risk during these operations is still not fully understood. Blowout is regarded as one of the most catastrophic events in offshore drilling operations; therefore implementation and maintenance of safety measures is essential to maintain risk below the acceptance criteria. This study is aimed at applying the Bayesian Network (BN) to conduct a dynamic safety analysis of deepwater MPD and UBD operations. It investigates different risk factors associated with MPD and UBD technologies, which could lead to a blowout accident. Blowout accident scenarios are investigated and the BNs are developed for MPD and UBD technologies in order to predict the probability of blowout occurrence. The main objective of this paper is to understand MPD and UBD technologies, to identify hazardous events during MPD and UBD operations, to perform failure analysis (modelling) of blowout events and to evaluate plus compare risk. Importance factor analysis in drilling operations is performed to assess contribution of each root cause to the potential accident; the results show that UBD has a higher occurrence probability of kick and blowout compared to MPD technology. The Rotating Control Devices (RCD) failure in MPD technology and increase in flow-through annulus in UBD technology are the most critical situations for kick and blowout.     

A guide for assessing control room operator performance using speed and accuracy,perceived workload,situation awareness,and eye tracking

In the petrochemical industry, control room operators must address safety-critical alarms and other tasks using complex interfaces. This study developed a guide for assessing human performance using standard human factors measurement tools, and tested the sensitivity of those tools with two interface designs (i.e., gray and black) at three levels of workload (i.e., easy, medium, and difficult). The guide measures human performance through speed and accuracy, perceived workload using two standard instruments (i.e., NASA Task Load Index (NASA-TLX) and Subjective Workload Assessment Technique (SWAT)), situation awareness through the Situation Awareness Global Assessment Technique (SAGAT), and gaze through eye tracking coordinates. Twelve engineering student participants completed one simulation session at each of the three workload levels using one of two interface designs. Workload was manipulated through the number of simulated events (failures) in each session. Overall, the speed and accuracy measures, workload ratings, and eye tracking showed sensitivity to differences in workload level, and situation awareness showed sensitivity to the interaction between workload level and interface type. None of the tools were sensitive to interface type alone. Accuracy was highest under easy workload. Time per failure decreased at higher workload levels. Perceived workload ratings from the SWAT increased as workload increased, but workload ratings from the NASA-TLX were not different across workload levels. When workload increased, situation awareness remained steady for the gray interface but decreased sharply for the black interface, illustrating an interaction effect. Finally, the percentage of time spent looking at different areas of the screen during steady-state periods differed among workload levels. The tools in this guide can be used in the petrochemical industry to make design decisions for control room interfaces when workload levels are a concern.     

基于Apriori算法的易燃易爆危险化学品储运火灾爆炸事故关键致险因素的挖掘

导致易燃易爆危险化学品储运火灾爆炸事故的因素繁多、关系复杂,挖掘关键致险因素是减少管理成本、提高防控效率的关键。研究了200例事故等级为较大事故以上的易燃易爆危险化学品储运火灾爆炸事故的原因,采用事故树分析法建立易燃易爆危险化学品储运火灾爆炸事故树,并运用频度统计法遴选出致险因素;在此基础上,建立基于Apriori算法的关联规则模型进行数据挖掘,共得到14个关键致险因素。通过对关键致险因素与易燃易爆危险化学品储运火灾爆炸事故之间关联规则的分析表明,关键致险因素与事故之间存在强关联规则,单一关键致险因素或其组合的存在必将导致事故的发生,为实现危险化学品储运精准化安全管理提供参考。     

高科技制造业环安卫风险管理系统

只要有危害源就会存在一定的风险。由于生产过程的需要,高科技制造行业往往使用大量有毒、危险化学品,生产环境与生产设备也不同于传统产业,也因此,如何运用有效地环安卫(环境保护、工业安全、职业健康)风险管理机制来避免各种危害源可能对企业造成的负面冲击,以降低高科技行业营运过程可能遭遇的环安卫风险一直是高科技行业风险管理者所面临的挑战。本文将介绍如何以PDCA持续改善的架构来贯穿高科技行业环安卫风险管理流程与风险管理概念。     

A preliminary analysis of aortic injuries in lateral impacts

Injuries to the aorta are among the more serious injuries that result from vehicle impacts, and often may be fatal. This article examines the incidence of aortic injuries in the United States and United Kingdom by using two international databases of real-world crashes. The main outcome of interest was the level of risk associated with each principal direction of force for drivers and front-seat passengers with respect to sustaining aortic injuries. The results indicate that the risk of sustaining an injury to the aorta is greater for near-side crashes than for far-side crashes. Further it is apparent that, given a near-side crash, the risk of an aortic injury is greater on the left side of the body (and left side of the vehicle) than on the right. It also was found that the delta-V of crashes where occupants sustained an injury to the aorta was considerably higher than crashes where occupants did not sustain aortic injuries. It is speculated that the anatomical asymmetry of the thorax might play a role in the differences seen in injury risk associated with different impact directions. The results presented in this article could be of use to both the emergency physician treating patients involved in motor vehicle collisions as well as the engineer involved in occupant design countermeasures. Limitations and further planned research are discussed.     

Confidence-based quantitative risk analysis for offshore accidental hydrocarbon release events

Quantitative risk analysis (QRA) has been widely used to conduct the assessment of offshore accidental risks. However, the accuracy and validity of QRA is significantly affected by uncertainties when subjective judgments are involved. Therefore, it is unrealistic to determine the probability of a hazardous event by using one single explicit value when safety experts have a relatively low confidence level in their judgments. This paper proposes a new methodology for incorporating uncertainties into conventional QRA using the concept of confidence level. Offshore hydrocarbon release hazards are focused on and a barrier and operational risk analysis (BORA-Release) method is selected as the basic model to illustrate the proposed methodology. A left–right (L–R) bell-shaped fuzzy number is employed and its membership curve is able to control its shape to represent different confidence levels. As to the complex geometry of the bell-shaped fuzzy number, an α-cut operation is introduced to conduct the arithmetic operations of the fuzzy number, and a defuzzification method with total integral value is chosen to match the α-cut operations and acquire complete information for the fuzzy numbers. In the meantime, an optimism index is used to describe the attitude of the decision-maker. One case study is provided in this paper to demonstrate the implementation of this method.     

Organizational Climate Metrics as Safety,Health and Environment Performance Indicators and an Aid to Relative Risk Ranking within Industry

The chemical, pharmaceutical and other related process industries are characterized by inherently hazardous processes and activities. To ensure that considered risk management decisions are made it is essential that organizations have the ability to rank the risk profiles of their assets and operations. Current industry risk ranking techniques are biased toward the assessment of the risk potential of the asset or operation. Methodologies used to assess these risks tend to be engineering-based and include, for example, hazard identification and event rate estimation techniques. Recent research has associated lagging safety performance indicators with metrics of organizational safety climate. Despite the evidence suggesting their potential usefulness, organizational climate metrics have not yet been exploited as a proactive safety, health and environmental performance indicator or as an aid to relative risk ranking. This paper summarizes research that successfully produced a statistical model of organizational climate and its relationship to site significant injury frequency rates, allowing the relative risk ranking of sites based upon organizational climate metrics. The responses to an industrial organizational survey are examined for a pharmaceutical company's sites in the United Kingdom, Sweden and the United States. Projection to Latent Structures Analysis is performed on the survey responses. The resultant models are shown to be able to accurately model the site significant injury frequency rates. The organizational climate metrics that discriminate between the safety performance levels of different sites are identified.