Empirical research on diffusion behavior of leaked gas in the ground

Chemical plants and gas utilities own large underground pipelines to transport material such as combustible gas. For example, city gas utilities in Japan have about 230,000 km of pipelines, even if only the pipelines to deliver gas to their customers are considered. Any accidents involving such pipelines can lead to enormous human and physical damage, and their security is therefore a top-priority issue for utilities. For the safety management of underground pipelines, in addition to assessment of the long-term reliability of pipeline materials, it is extremely important to understand the diffusion behavior of gases in the ground, such as the diffusion range and time, in the case of leakage, and the impact on the surrounding area is a fundamental factor to be considered in the design and maintenance of safe facilities and for emergency response. Although many papers introduce the situations of gas diffusion in the atmosphere such as indoor and outdoor conditions, only fundamental surveys have been conducted on gas diffusion in the ground, and there have been few full-scale empirical studies. This study reports the results of the verification of the diffusion behavior with full-scale gas leakage experiments simulating real underground pipelines, as well as the outcomes of the applicability test of a numerical simulation model investigated and proposed based on the results. This technical knowledge regarding security will contribute to further improvement of safety in the industry.     

由“7·28”南京丙烯管道爆燃事故探讨我国地下管道存在的安全问题

＂7·28＂南京丙烯管道爆燃事故和近期发生的一系列管道事故反映出我国在地下管道安全方面存在的问题。在事故原因分析与共性问题探讨的基础上,结合欧美国家在管道安全管理中的成功做法,从加强法制建设、合理规划城市布局、进行重大危险源普查并建立监测监控系统、强化城镇地面开挖施工安全管理、加强风险沟通提高公众应急能力等方面提出了对策建议。     

国外油气管道安全管理经验及启示

近年来,我国油气管道发展迅猛,管道数量激增;上世纪70!80年代修建的管道逐渐进入老龄化,管道事故呈上升趋势。文章对美国、加拿大和欧盟国家油气管道的发展现状和事故情况进行了介绍,重点对以美国为代表的国外油气管道安全管理先进经验进行了分析,并针对当前我国油气管道安全管理的形势和问题,提出了一些建议。     

基于IAHP和灾变链式方法的城市油气管道风险诱因与预警研究

城市油气管道穿越城区街道、建筑和居民区等特殊地段,保障其安全运行具有重要意义。为实现城市油气管道风险早期预警,基于城市与野外长输油气管道风险对比分析,识别城市油气管道风险预警指标;建立城市油气管道风险预警指标体系,采用区间层次分析法对预警指标重要度进行定量排序,确定关键预警监测点;并依据灾变链式理论,构建城市油气管道重大事故灾变链式模型,研究管道风险演化过程,发现灾变前兆进行断链减灾。研究结果表明:“腐蚀”及“第三方破坏”占据城市油气管道失效致因比重最大,风险因子“油气管道与市政管道距离”以及“城市工程施工作业”应作为城市油气管道重点监测点。同时,围绕城市油气管道风险预警需致力于孕源断链。     

An integrated methodology to manage risk factors of aging urban oil and gas pipelines

Aging urban oil and gas pipelines have a high failure probability due to their structural degradation and external interference. The operational safety of the aging urban oil and gas pipeline is challenged by different hazards. This paper proposes a novel methodology by integrating an index-based risk evaluation system and fuzzy TOPSIS model for risk management of aging urban oil and gas pipelines, and it is carried out by evaluating the priority of hazards affecting pipeline safety. Firstly, the hazard factors of aging urban oil and gas pipelines are identified to establish an index-based risk evaluation system. Subsequently, the fuzzy TOPSIS model is employed to evaluate the importance of these hazard factors and to decide which factors should be managed with priority. This work measures the importance of a hazard factor from three aspects, i.e. occurrence (O), severity (S) and detectability (D), and the weights of these three parameters are determined by a combination weight method. Eventually, the proposed methodology is tested by an industrial case to illustrate its effectiveness, and some safety strategies to reduce the operational risk of the pipeline are presented. The proposed methodology is a useful tool to implement more efficient risk management of aging urban oil and gas pipelines.     

城市燃气管线泄漏致灾灾害链研究

为了研究城市燃气管线泄漏致灾灾害链,对灾害链的形成机理进行分析,建立灾害链模型,并通过计算灾害链发生概率对灾害链断链减灾方法进行研究。结果表明,城市燃气管线泄漏致灾灾害链可分为致灾环、激发环、损害环三部分;灾害链中因管道裂纹导致的中毒窒息灾害事故、管道穿孔导致的中毒窒息灾害事故及火灾等链条的发生概率较高;致灾环是灾害链断链减灾的关键环节,在城市安全管理中应落实应急预案制度并加强对城市居民的防灾减灾安全教育力度。     

石油天然气长输管道危险性分析

基于四川省天然气长输管道事故的统计资料(即1969—1990年间发生的155次事故),结合1990年以后,直至1998年四川发生的管道事故,对油气长输管道所面临的各种可能的危险因素进行综合分析,找出油气长输管道事故诱因主要来自管道腐蚀、材料缺陷、设计和施工质量、不良环境条件和第三方破坏。进而分别探讨四大危险性因素对管道安全运行的影响,并从理论和工程角度提出了预防和控制油气长输管道事故的对策和建议。     

An integrated quantitative risk analysis method for natural gas pipeline network

Natural gas industry is developing rapidly, and its accidents are threatening the urban safety. Risk management through quantitative assessment has become an important way to improve the safety performance of the natural gas supply system. In this paper, an integrated quantitative risk analysis method for natural gas pipeline network is proposed. This method is composed of the probability assessment of accidents, the analysis of consequences and the evaluation of risk. It is noteworthy that the consequences analyzed here include those of the outside and inside gas pipelines. The analysis of consequences of the outside pipelines focuses on the individual risk and societal risk caused by different accidents, while those of the inside pipelines concerns about the risk of the economic loss because of the pressure re-distribution. Risk of a sample urban gas pipeline network is analyzed to demonstrate the presented method. The results show that this presented integrated quantitative risk analysis method for natural gas pipeline network can be used in practical application.     

城区天然气管道泄漏数值模拟与爆炸危害分析

在人口密度为三级和四级的城区内,密集的高建筑物对天然气管道泄漏后的扩散和流场形成产生重要影响。本文以某城市的实际情况为例,建立多建筑物的空间几何模型,采用k-ε湍流方程,SIMPLE算法,模拟了在三种不同风流速度、三种不同压力条件下,城区天然气管道泄漏气体在多建筑物地形中的扩散情况。根据模拟结果,依据天然气的爆炸极限,对模拟结果及其火灾爆炸危害的范围进行了对比分析。结果表明,CH4气体的泄漏扩散同时受管道压力、风流速度和周围建筑物的影响;同时受当地风速的影响,泄漏气柱在风流作用下会发生偏折,造成阻挡风流的建筑物内侧危险气体浓度升高,大大增加建筑物周围环境的危险性。研究结果对城区天然气管道的建设具有一定的指导意义。     

城市天然气管道风险特征与肯特法的改进

根据城市高压天然气管道特点,将适合于城市天然气管道风险分析的肯特评分法加以改进,包括调整评分项目和事故因素权重,使其成为适于城市天然气管道的风险分析法。将改进后的肯特评分法应用于常州21km高压天然气管道的风险评价,得出8个相对高风险管段,其分析结果可作为安全管理人员合理分配维护资源的理论依据。工程应用实例证明:改进后的肯特法具有较强的可行性,是城市高压天然气管道风险评估的有效工具。     

城市地下管线系统可靠性分析

随着城市经济水平的提高、城市规模的扩大和现代化步伐的加快，城市地下管网越来越庞大，越来越复杂，种类也越来越多，所担负的城市人民群众赖以生存的物质基础的作用也越来越强。对城市地下管线失效的特点和系统可靠性进行深入分析，为政府部门做好日常安全管理工作，做出科学合理的决策，实现地下管线安全预警等提供依据，对预防事故发生和减少生命财产损失具有现实的指导意义。     

Quantitative assessment of environmental risk due to accidental spills from onshore pipelines

The transport of hazardous materials by pipeline is widely used for the transfer of significant quantities of oil and chemicals. Due to the extremely low frequency of spills, pipelines are considered the safest mode for the land transportation of hazardous substances. Accident records, while confirming that Loss of Containment (LOC) events are rare, also point out the major-accident hazard of pipelines, due to the extremely severe potential consequences of spills. Quantitative Risk Analysis (QRA) techniques have been applied to pipelines since many years with the aim of evaluating risk for workers or exposed population. However, releases of liquids, as oil and oil products, also create an hazard to the environment, due to the potential of extensive soil and groundwater contamination. An integrated model was developed for the environmental Risk Analysis of spills from pipelines. Specific environmental risk indexes were defined, expressing the risk of soil and groundwater contamination, both in physical and economic terms. A case-study is presented and discussed to illustrate the features of the methodology. The results confirmed that the proposed model may be considered an important tool within a comprehensive approach to the management of risk related to onshore pipelines.     

Societal risk acceptance criteria for gas distribution pipelines based on incident data from the United States

A significant number of pipeline operators use pipeline integrity management (PIM) to improve pipeline safety and reliability. Risk assessment is a critical step in PIM, because it determines the necessity of conducting the following steps in PIM for certain pipelines. Risk acceptance criteria are required in the process of risk assessment. Individual risk and societal risk are most frequently adopted as the two indicators of the risk acceptance criteria. To the best of the authors’ knowledge, quantitative societal risk acceptance criteria, especially for gas distribution pipelines, do not exit. The aim of this paper is to establish the societal risk acceptance criteria for gas distribution pipelines. Hence, FN curves were established using historical incident data from 2002 to 2017 provided by the U.S. Department of Transportation (DOT). Linear regression and the ALARP principle are used in evaluating the limits of the negligible line and intolerable line to obtain a graphical societal risk acceptance criterion for gas distribution pipelines. A line having a slope of −1.224, and an anchor point of (1, 8.413 × 10⁻⁷) is proposed as the negligible line. Further, the intolerable line has a slope of −1.224, and an anchor point of (1, 2.524 × 10⁻⁶). Both the negligible risk and the intolerable risk for the gas distribution pipeline are lower than the current societal risk acceptance criteria for hazardous installations. The reasons for these relatively lower risk acceptance criteria are discussed.     

城市轨道交通工程建设期间危险有害因素分析

通过对国内城市轨道交通工程建设期间典型事故的统计分析,总结城市轨道交通工程建设期间可能存在的危险有害因素。分析结果表明,城市轨道交通工程建设期间事故多发的主要原因有:不同施工工法引起的地层坍塌和结构物破坏;不良地质体诱发的安全事故;地下管线引起的安全事故;沿线临近建筑、构筑物引起的安全事故;施工管理不当造成的安全事故等。     

An urban pipeline accident model based on system engineering and game theory

Urban pipeline accidents are caused by complex social-technical factors, in which urban communities and pipeline systems are involved. Such accidents can thus be investigated from the viewpoint of system engineering. System-Theoretic Accident Model and Processes (STAMP) is a systemic method for safety assessment, which has been adopted in many domains. This approach can provide deep insights of accident causes by considering direct and indirect factors. Meanwhile, competition and cooperation between stakeholders in accidents are observed. Therefore, these parties can also be analyzed with the game theory. That is, stakeholders in STAMP can be regarded as players in game. The aim of this paper is to provide a new insight to analyze urban pipeline accidents by considering both STAMP and game theory. In this paper, we proposed an accident model for urban pipelines, with a case study of China-Qingdao pipeline accident occurred in 2013. We concluded that accident reasons can be investigated in-depth and lessons can be learned from analyzing causal factors by using STAMP. Based on results generated from STAMP, we applied the game theory to analyze roles that government and companies act in the China-Qingdao urban pipeline accident. The results show that current punishment and incentive systems are incomplete, lacking of the driving force and constraining force for the stakeholders involved in the accident.     

工业管道压力试验应注意的安全问题

按有关规定,我国压力管道分为长输管道、工业管道和公用管道,工业管道是指工业企业所属的用于运输工艺介质的工艺管道、公用工程管道和其他辅助管道,即工业企业内运行的压力管道均为工业管道.主要介绍了我国工业企业内工业管道相关运行维护管理与检验现状,重点强调工业管道运行中安全性能,及对工业安全性能确定所进行的压力试验的相关要求,为企业内部如何防止工业管道事故发生,实现安全生产提供有益的探索.     

Dynamic probability assessment of urban natural gas pipeline accidents considering integrated external activities

Urban gas pipelines usually have high structural vulnerability due to long service time. The locations across urban areas with high population density make the gas pipelines easily exposed to external activities. Recently, urban pipelines may also have been the target of terrorist attacks. Nevertheless, the intentional damage, i.e. terrorist attack, was seldom considered in previous risk analysis of urban gas pipelines. This work presents a dynamic risk analysis of external activities to urban gas pipelines, which integrates unintentional and intentional damage to pipelines in a unified framework. A Bayesian network mapping from the Bow-tie model is used to represent the evolution process of pipeline accidents initiating from intentional and unintentional hazards. The probabilities of basic events and safety barriers are estimated by adopting the Fuzzy set theory and hierarchical Bayesian analysis (HBA). The developed model enables assessment of the dynamic probabilities of consequences and identifies the most credible contributing factors to the risk, given observed evidence. It also captures both data and model uncertainties. Eventually, an industrial case is presented to illustrate the applicability and effectiveness of the developed methodology. It is observed that the proposed methodology helps to more accurately conduct risk assessment and management of urban natural gas pipelines.     

我国城市灾害风险应对现状及对策研究

阐述了城市灾害的分类;从城市灾害预防与控制,应急反应与救援等方面分析我国在城市灾害风险控制与应对上的不足;提出8个方面的对策。该对策研究包括:建立城市安全规划、风险防范和危机管理法律体系;实施城市防灾减灾规划并融入城市规划中;完善城市灾害风险决策支持系统和信息管理系统;实行安全规划风险评价机制;加快防灾减灾综合管理机构建设;建立科学、完善的应急救援体系;加强安全教育和防灾减灾宣传;加强城市安全科学研究与交流。该研究结果对如何提高我国城市灾害风险预防与控制能力及应急救援水平具有重要的借鉴和指导作用。     

Airbag for the closing of pipelines on explosions and leakages

This paper is a result of international effort aimed at the construction of a device for quick closing of pipelines in the case of explosion propagation and/or chemical leakage. Such a problem exists in industries where flammable substances are transported by pipelines. The basic solution principle was the idea to use airbags similar to those utilized in cars.

Two pipeline applications were taken into consideration: a low-pressure module able to suppress explosion propagation and a high-pressure module to stop leakages from, e.g. natural gas pipeline capable to be used for duct diameters up to 0.6 m, pressures up to 5 MPa and reaction times of 50 ms. It was necessary to construct a new airbag, capable of withstanding up to 10 bar pressure. The choice of material was critical to ensure sufficient strength and chemical resistance while retaining impermeability.

CFD modeling of the bag deployment into a pipe flow and analysis of the bag shapes was also completed. Two gas generators were constructed and tested with novel propellant materials.

Different airbag models were tested to evaluate their effectiveness. Risk analysis approach was applied to evaluate the safety and economic benefits of the new technology in different fields of application.