Rail ruminations for process safety improvement

Process safety practices have undergone multiple refinements over the past few decades, but major accidents continue to occur. Most organizations strive to improve performance by strengthening existing methods or by adopting new and/or different approaches. Central to these continual improvement efforts is the practice of applying lessons learned as a means to drive out potential risk exposures. Often, lessons learned may be transferred from other industries; indeed, high-performing organizations regularly benchmark practices outside of their immediate industry.In pursuit of continual process safety improvement, this paper examines risk management practices in the Rail Industry, and explores how methods intended for managing passenger and public rail safety may be transferred to drive continual improvement of process safety. Rail safety has its roots in engineered safety solutions; modern practices have additionally embraced the human aspects of safety performance. A selection of approaches for rail safety assessment and risk management are described in three areas considered fundamental to safety management: management of systems, management of technology, and management of human elements. In light of these examples, the authors provide views regarding how the field of process safety management may leverage the rail experience.     

On the operator action analysis to reduce operational risk in research reactors

Human errors during operation and the resulting increase in operational risk are major concerns for nuclear reactors, just as they are for all industries. Additionally, human reliability analysis together with probabilistic risk analysis is a key element in reducing operational risk. The purpose of this paper is to analyze human reliability using appropriate methods for the probabilistic representation and calculation of human error to be used alongside probabilistic risk analysis in order to reduce the operational risk of the reactor operation. We present a technique for human error rate prediction and standardized plant analysis risk. Human reliability methods have been utilized to quantify different categories of human errors, which have been applied extensively to nuclear power plants. The Tehran research reactor is selected here as a case study, and after consultation with reactor operators and engineers human errors have been identified and adequate performance shaping factors assigned in order to calculate accurate probabilities of human failure.     

Determination of human error probabilities in maintenance procedures of a pump

The “human factor” constitutes an important role in the prediction of safe operation of a facility. Hence, information about human capacities and behaviours should be applied methodically to increase the safety of a systematic process. This paper provides an analysis of human factors in pre- and post-maintenance operations. For possible failure scenarios, this paper considers the procedures for removing process equipment from service (pre-maintenance) and returning the component to service (post-maintenance). In this study, a pump is used as the test example. For each scenario, the human error probability (HEP) is calculated for each activity, using the Human Error Assessment and Reduction Technique (HEART) which is commonly implemented technique in industry, can also be applied in the analyses of safety cases. HEART is a reliable technique for comparing HEP and its approach is based on the degree of error recovery. Consequences are also assessed for each activity in this methodology. The final value of risk for each activity is assigned by combining error likelihood and related consequences. When the calculated risk is beyond acceptable levels, risk management strategies are provided to increase the safety of the maintenance procedures. The most probable human errors for a considered case study are related to the activities of “draining lines” and “open valves”. These two activities have high HEPs, which are 9.57E−01 and 9.62E−01, respectively.     

航空维修差错分析及其管理

航空维修差错是诱发或直接导致飞行事故最重要的原因之一 ,对维修差错进行分类和分析有助于航空安全。笔者在分析航空维修环境变化的基础上 ,基于Reason模型构建了维修差错分类与诱因分析的框架 ,并结合机务维修的实际情况 ,对框架所包括的不安全行为、不安全行为的先兆、不安全的管理及组织因素进行了初步编码。文章还简要论述了维修差错的管理技术 ,指出借助框架编制详细的差错分类与分析编码系统是发展的方向。     

Dynamic-risk-informed safety barrier management: An application to cost-effective barrier optimization based on data from multiple sources

An integrated approach for performance assessment and management of safety barriers in a systemic manner is needed concerning the prevention and mitigation of major accidents in chemical process industries. Particularly, the effects of safety barriers on system risk reduction should be assessed in a dynamic manner to support the decision-making on safety barrier establishments and improvements. A simulation approach, named Simulink-based Safety Barrier Modeling (SSBM), is proposed in this paper to conduct dynamic risk assessment of chemical facilities with the consideration of the degradation of safety barriers. The main functional features of the SSBM include i) the basic model structures of SSBM can be determined based on bow-tie diagrams, ii) multiple data (periodic proof test data, continuous condition-monitoring data, and accident precursor data) may be combined to update barrier failure probabilities and initiating event probabilities, iii) SSBM is able to handle uncertainty propagation in probabilistic risk assessment by using Monte Carlo simulations, and iv) cost-effectiveness analysis (CEA) and optimization algorithms are integrated to support the decision-making on safety barrier establishments and improvements. An illustrative case study is demonstrated to show the procedures of applying the SSBM on dynamic risk-informed safety barrier management and validate the feasibility of implementing the SSBM for cost-effective safety barrier optimization.     

安全工程技术领域数字孪生应用研究综述

为系统了解安全工程技术领域数字孪生应用现状并预测其发展趋势,综述国内外安全工程领域数字孪生应用进展,主要包括数字孪生在动态仿真、安全监控、故障诊断、运维控制、预测性维护等方面的应用,展望未来数字孪生在安全工程技术领域的研究方向.研究结果表明:数字孪生技术在机械工业、航天航空、石油化工、矿山、电气、船舶运输、建筑施工、城...     

Maintenance-related major accidents: Classification of causes and case study

The potential for major accidents is inherent in most industries that handle or store hazardous substances, for e.g. the hydrocarbon and chemical process industries. Several major accidents have been experienced over the past three decades. Flixborough Disaster (1974), Seveso Disaster (1976), Alexander Kielland Disaster (1980), Bhopal Gas Tragedy (1984), Sandoz Chemical Spill (1986), Piper Alpha Disaster (1988), Philips 66 Disaster (1989), Esso Longford Gas Explosion (1998), Texas City Refinery Explosion (2005), and most recently the Macondo Blowout (2010) are a few examples of accidents with devastating consequences.Causes are being exposed over time, but in recent years maintenance influence tends to be given less attention. However, given that some major accidents are maintenance-related, we intend to concentrate on classifying them to give a better insight into the underlying and contributing causes.High degree of technological and organizational complexity are attributes of these industries, and in order to control the risk, it is common to deploy multiple and independent safety barriers whose integrity cannot be maintained without adequate level of maintenance. However, maintenance may have a negative effect on barrier performance if the execution is incorrect, insufficient, delayed, or excessive. Maintenance can also be the triggering event.The objectives of this article are: (1) To investigate how maintenance impacts the occurrence of major accidents, and (2) To develop classification schemes for causes of maintenance-related major accidents.The paper builds primarily on model-based and empirical approaches, the latter being applied to reports on accident investigation and analysis. Based on this, the Work and Accident Process (WAP) classification scheme was proposed in the paper.     

人失误模型在防止变电所检修事故中的应用

针对变电所检修事故的特点,认为人失误是导致该类事故发生的主要原因。运用安全人机工程学基本原理,分析了变电所检修过程中人失误产生的原因,在研究了以人失误为主因的事故模型基础上,进一步从人的特性、人机功能的分配、人机界面的设计、安全管理和环境因素五个方面人手构建了以人失误为主因的变电所检修事故模型,基于该模型提出了有效、合理的避免或减少变电所检修事故的五点对策措施。以期能为变电所检修事故的预防起到积极的指导作用。     

Risk assessment tools incorporating human error probabilities in the Japanese small-sized establishment

Although it has been estimated that as many as 80% of all occupational accidents have human errors as a cause, no risk assessment tools incorporating human-related elements have been developed for small companies. Human error probability (HEP) and human error analysis (HEA) have been used for large-scale, safety-critical industries for last three decades, but these tools are not suitable for smaller, more general industries that comprise the majority of accident settings.Here, we describe and verify a risk assessment tool that includes human-related elements for small companies. The tool expands on traditional risk assessment methods, such as matrix, risk graph and numerical scoring method, by adding human-related elements. The tool is easy-to-use in occupational environments, and includes assessments of human behavior and potentially outdated machinery at work place.     

民航机务维修系统安全风险监测

从人的因素、飞机的因素、环境因素和管理因素4方面分析了民航机务维修系统安全风险影响因素,结合专家调查意见建立了机务维修系统安全风险监测指标体系,并给出各个指标的含义及其衡量方法。根据机务维修系统安全风险指标及其数据特点,建立了行业机务维修系统安全风险模糊综合评价模型,并进行实例分析。结果表明,采用笔者建立的指标体系和风险模型可以方便地进行机务维修系统的安全风险评价和预警,从而找出主要的安全风险影响因素,为采取安全风险管理措施提供依据。     

地铁隧道施工安全风险演化的BP-SD模型研究

为深入研究地铁隧道施工风险的动态演化过程,结合系统动力学(SD)、误差反向传播(BP)神经网络与平均影响值（MIV）算法,确定模型中影响因素间的因果关系和影响函数,构建地铁隧道施工风险演化的BP-SD模型。模型仿真结果表明:安全管理风险系统与施工人员风险系统的值的变化对地铁隧道施工风险值影响最大,施工环境系统的值的变化对地铁隧道施工风险值影响次之,机械设备系统的值的变化对地铁隧道施工风险值影响最小。因此,可通过降低安全管理风险值与施工人员风险值控制地铁隧道施工风险发生的概率。     

Fuzzy risk modeling of process operations in the oil and gas refineries

Operating several assets has resulted in more complexity and so occurrence of some major accidents in the refining industries. The process operations risk factors including failure frequency and the consequence components like employees' safety and environment impacts, operation downtime, direct and indirect cost of operations and maintenance, and mean time to repair should be considered in the analysis of these major accidents in any refinery. Considering all of these factors, the risk based maintenance (RBM) as a proper risk assessment methodology minimizes the risk resulting from asset failures. But, one of the main engineering problems in risk modeling of the complex industries like refineries is uncertainty due to the lack of information. This paper proposes a model for the risk of the process operations in the oil and gas refineries. The fuzzy logic system (FLS) was proposed for risk modeling. The merit of using fuzzy model is to overcome the uncertainty of the RBM components. This approach also can be accounted as a benchmark for future failures. A unified risk number would be obtained to show how the criticality of units is. The case study of a gas plant in an oil refinery is performed to illustrate the application of the proposed model and a comparison between the results of both traditional RBM and fuzzy method is made.For the case study, 26 asset failures were identified. The fuzzy risk results show that 3 failures have semi-critical level and other 23 failures are non-critical. In both traditional and fuzzy RBM methods, some condenser failures had the highest risk number and some pumps were prioritized to have the lowest risk level. The unit with unified risk number less than 40 is in the non-critical conditions. Proposed methodology is also applicable to other industries dealing with process operations risks.     

Evaluation of risk and cost using an age-dependent unavailability modelling of test and maintenance for standby components

The improvement of safety in the process industries is related to assessment and reduction of risk in a cost-effective manner. This paper addresses the trade-off between risk and cost related to standby safety systems. An age-dependent unavailability model that integrates the effects of the test and maintenance (T&M) activities as well as component ageing is developed and represents the basis for calculating risk. The repair “same-as-new” process is considered regarding the T&M activities. Costs are expressed as a function of the selected risk measure. The time-averaged function of the selected risk measure is obtained from probabilistic safety assessment, i.e. the fault tree analysis. This function is further extended with inclusion of additional parameters related to T&M activities as well as ageing parameters related to component ageing. In that sense, a new model of system unavailability, incorporating component ageing and T&M costs, is presented. The testing strategy is also addressed. Sequential and staggered testings are compared. The developed approach is applied on a standard safety system in nuclear power plant although the method is applicable to standby safety systems that are tested and maintained in other industries as well. The results show that the risk-informed surveillance requirements differ from existing ones in technical specifications, which are deterministically based. Moreover, the presented approach achieves a significant reduction in system unavailability over a relatively small increase of total T&M costs.     

Developing a risk-based maintenance model for a Natural Gas Regulating and Metering Station using Bayesian Network

During the last decades, the vital role of maintenance activities in industries including natural gas distribution system has cleared up progressively. High costs may induce to reduced maintenance and, in turn, lead to a lower availability and high risk of undesired events. Therefore, a probabilistic model, based on an acceptable level of risk, is required to avoid under and over estimation of maintenance time interval. This paper presents an advanced Risk-based Maintenance (RBM) methodology to optimize maintenance time schedule. Bayesian Network (BN) is applied to model the risk and the associated uncertainty. The developed method can assist the asset managers to work out the exact maintenance time for each component according to the risk level. To demonstrate and discuss the applicability of the methodology, a case study of Natural Gas Reduction and Measuring Station in Italy is considered. Results prove that the most critical components are the calculator and pilots, while the most reliable one is the odorization. Furthermore, the pressure and temperature gauge (PTG), the remote control system (RCS) and the meter are predicted as the components that require less time to transit from minor risk to catastrophic risk.     

基于人因失误分析的医院电气安全管理研究

医院是重点用电单位,用电的安全性和供电可靠性都比较高,但因不可抗力、供电系统故障、医院管理问题、人为失误等方面的原因,仍存在发生各类电气突发事件的风险。其中,由人的误操作或不安全行为因素而诱发的电气方面的突发事件已成为医院非医疗事故的主要原因。文章针对医院电气安全操作方面的人因失误,从个人和组织两个角度进行了失误原因的分析,认为人的失误既受个体因素的影响,也受环境、制度和管理水平的影响。在此基础上,提出完善相关规章制度建设、加强教育与培训等,从组织制度建设、人员技术素质提高等方面,提出预防与减少人因失误的措施与方法,提高供配电质量,为医院医疗工作提供有效的电气安全后勤保障。     

基于DBT-DBN模型的气化炉超温动态风险分析

为加强煤气化装置核心设备气化炉的安全风险管理,利用动态领结(DBT)模型和动态贝叶斯网络(DBN)相结合的风险分析方法,构建气化炉超温事故风险分析模型.首先,分析设备故障的时序性,建立超温事故的DBT模型,结合模糊评价确定设备故障的发生概率;然后,将DBT映射到DBN中,将故障维修的动态特征定义为转移概率,双向推理气化...     

Reconsidering autoignition in the context of modern process safety: Literature review and experimental analysis

Autoignition is regarded as the spontaneous combustion of a fuel without an apparent ignition source. With respect to fires and explosions in the process industries, the autoignition hazard is one that requires management and consideration. Despite the importance of understanding the autoignition hazard, the literature on the topic is often disappointingly sparse and inconsistent. Experimental methods don't adequately represent real-world conditions and are complicated by experimental error, invoking the need for a reconsideration of autoignition as it pertains to process safety. This work utilized the ASTM E659 method to study potential experimental error for the purpose of improving the process safety community's understanding of autoignition phenomena. Of interest to this study were effects of humidity and suspected occurrences of cool flames, two sources of error which have not been fully explained in the literature. For the fuels tested, results show that humidity has only a slight effect on overall autoignition behavior. However, this study's examination of cool flames suggests that they could be a common occurrence in this testing method. Analysis of these experiments show that cool flames can feature significant exothermic effects and are thus of concern from a perspective of risk management. In addition, this work proposes a novel criterion for a more conservative assessment of autoignition experiments, which results in less subjectivity of analysis.     

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。     

海洋石油轮班作业风险定量分析方法研究

长期以来,海洋石油领域风险研究主要集中在对设施的潜在失效概率和后果研究方面,而对于人员可靠性及风险管理方面的研究较弱。然而,据统计资料显示,海上设施在其生命周期内的设计、建造和生产作业等各个阶段中发生的事故大多与人为错误和组织错误（HOE）有关联。在海洋工程领域,开展人员可靠性分析（HRA）的研究工作具有重要意义。根据海上作业的特殊性及轮班制度的特点,推导出轮班风险的定量分析公式,据此计算出每个工作日轮班风险的相对大小,然后结合我国海上作业的实际情况,对影响轮班风险的可变因素进行了敏感性分析,为风险控制与管理提供参考。     

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.