B10铜镍合金与H62黄铜的电偶腐蚀及电绝缘研究

主要研究了船舶海水系统中B10铜镍合金与H62黄铜间的电偶腐蚀性能及电绝缘控制方法。通过电位监测、极化曲线测试考察了两种材料的电偶腐蚀倾向;通过电偶腐蚀试验、SEM观察和EDS分析考察了试样的电偶腐蚀程度、微观腐蚀形貌和成分变化;通过串联不同阻值电阻的模拟电绝缘试验,测定了两材料偶合的电绝缘判据。结果表明,B10与H62黄铜间存在明显的电偶腐蚀倾向,直接偶连时H62黄铜发生严重的脱锌腐蚀。电绝缘技术是控制电偶腐蚀的有效措施之一,串联电阻大于等于20kΩ时,可基本消除B10与H62黄铜间的电偶腐蚀。     

A hybrid machine learning model for predicting crater width formed by explosions of natural gas pipelines

Despite the existence of industry models for estimating the crater width formed by the explosion of natural gas pipelines, their applicability is still limited since the complex formation mechanisms. In this work, a novel hybrid model was developed to predict crater width formed by explosions of natural gas pipelines, using artificial neural networks (ANN) as the fundamental predictor. Based on the historical accident records, the proposed hybrid model was trained by the pipeline parameter, the operating condition, the installation parameter, and the crater width. A novel nature-inspired optimization algorithm, i.e., the Lévy-Weighted Quantum particle swarm optimization (LWQPSO) algorithm, was proposed to optimize the ANN model's parameters. Three machine learning models were developed for comparative reasons to predict the crater width. The use of precision and error analysis indicators assesses prediction performance. The results show that the proposed hybrid model (LWQPSO-ANN) has high prediction accuracy and stability, which outperforms QPSO-ANN-based benchmark hybrid models and the model without an optimizer (Support Vector Machine, SVM). The parameter sensitivities of the proposed algorithm, including the maximum number of iterations, population size and contraction-expansion coefficient, were determined. The proposed hybrid model is expected to support the quantitative risk assessment (QRA), Right-of-Way (ROW) definition and the inherently safer design of the underground parallel pipelines.     

陆上油气管道受高压直流接地极干扰的腐蚀与防护实例分析

高压直流接地极放电时会对附近的管道产生强烈的电干扰,导致管道腐蚀加速,为了预测高压直流接地极对埋地管道的干扰程度并及时筛选合适腐蚀防护措施,利用数值模拟技术计算高压直流干扰下管道的干扰电位以及管体腐蚀速率,并结合相关标准对干扰水平进行评估。在此基础上,研究“单独管道方采取措施”、“管道方和电力方均采取措施”、“电力接地极更换极址”3种方案下的腐蚀防护效果。研究结果表明:对当前极址来说,需要管道方安装大量措施同时电力方对放电电流进行控制才能达到目标;而高压直流接地极极址土壤电阻率较低的情况下可以大幅降低对附近管道的干扰水平;就本文所列工程案例来说,更换极址是比较经济的方案。     

Quantifying reputation loss of pipeline operator from various stakeholders’ perspectives – Part 1: Prioritization

Quantifying reputation loss (RL) due to pipeline damage is commonly generalized based on the owner's definition. This one-way perspective of portraying RL is unfair and unrealistic and consequently miscalculates the impact assessment of pipeline damage; hence, inaccurate risk prediction. It is crucial to develop a model to quantify qualitative RL to avoid unpredicted risk. Thus, this article provides a framework for a procedure to calculate RL by utilizing the factors identified in a previous study. In this paper (Part 1), the prioritization of factors based on the stakeholders' perspectives is presented. The factors were grouped into stakeholder-influenced categories and prioritized by a fuzzy analytic hierarchy process based on the feedback gained from the stakeholders, i.e., investors, customers, employees and the public. The result shows that factor D3, “Accident severity”, was ranked highest by all stakeholders. The priority vector for each factor obtained was assigned as a weight of the factor. The pipeline owner's reputation loss model (RLM) is developed by applying the obtained priority vectors in the subsequent paper (Part 2). The developed model was verified by experts as a comprehensive, clear, objective, practical and moderately reliable model. The model was applied to a case study and eventually produced a lower risk value when compared with the currently used model. It is proven that RL factors can be quantitatively measured and can simultaneously improve pipeline damage impact assessment. Thus, a risk-based inspection schedule can be managed comprehensively.     

浅析水土保持监理在长输管道建设中的实施

文章结合川渝地区天然气管网调整改造工程-北外环集输气管道建设中水土流失治理监理实施情况,着重介绍了长输管道工程建设中地面开挖破坏造成水土流失的特点及成因,指出在长输管道工程建设中实施水土保持监理工作的法律及技术规范方面的依据,从8个方面提出施工现场水土保持监理的重点,并进行阐述和探讨。最后提出对此项工作的若干认识。     

Impact of flood water on the technical condition of natural gas transmission pipeline valves

Maintaining the reliability of a transmission system's operation is an extremely important issue in the context of ensuring the continuity of gas delivery to customers. Threats to maintaining the reliability of a transmission system's operation may appear at any stage of transmission, and the most common reasons for this are corrosion, material defects or accidental damage. The paper presents the impact of flood water on transmission valves in the context of possible threats to ensuring the technical safety of gas supplies. Hazards are described which relate to the chemical composition of flood water, which may cause corrosion of valve elements and risk of loss of gas pipeline stability caused by flooding. In the context of the design of a natural gas transmission network, the strength aspects and the phenomenon of corrosion are described. The results of tests related to a specific example are presented. The finite element method (FEM) is used to build ball valve models. Two types of valves are modelled for nominal pipeline diameters of 50 mm (DN50) and 200 mm (DN200). The results of the presented analysis show that the leak tightness of the tested valve flange connections was mainly influenced by changes in their operating conditions because the occurring additional forces and moments caused significant changes in the load balance of the flange connections.     

Subsea pipelines incidents prevention: A case study in Brazil

There are more than 4000 subsea pipelines in Brazil. These pipes include umbilicals, drilling risers, flexible risers, rigid risers, hybrid risers, flowlines, and export pipelines. Despite all standards, regulations, guides, and risk management tools designed to avoid events, subsea pipeline incidents still occur, revealing possible failures in companies' risk control. Identifying similarities between different subsea pipeline failure events is crucial to improving the design, risk management practices, and regulation requirements, besides promoting accident prevention. This paper proposes applying the life cycle and management practices combined to analyze subsea pipeline incidents from the RDI (Detailed Incident Report) and investigations reported to ANP (Brazilian National Agency of Petroleum, Gas, and Biofuels), the Brazilian safety regulatory agency. Furthermore, subsea pipeline incidents data were analyzed: correlated circumstances, consequences, and causes. The results show that most riser and flowlines causal factors are related to equipment failures, and recurrent root causes are design errors and integrity control. Based on the proposed approach, it was possible to identify gaps in most riser and flowlines accident investigations since there are few causal factors, root causes, and the absence of riser and flowlines failure mode and mechanisms. Therefore, the development of accident recommendations can be compromised. Thus, this paper proposes improvements to current Brazilian regulations to clarify the minimal subsea pipeline accident investigation requirements.     

长输油气管线安全生产事故监测预警平台设计与实现

阐述了适用于长输油气管线安全生产事故应急救援全过程的事故监测预警平台的整体结构和实现要点,主要从长输油气管线的工作运行和事故特点出发,结合安全生产事故应急救援过程中各环节的业务需求,提出监测预警平台的建设目标和适用范围,对平台的需求进行分析,并进一步对平台的构建思路进行讨论。其中重点从应急预防、应急准备、应急响应和应急恢复四个阶段的应急任务和需求入手,提炼出长输油气管线安全生产事故监测预警平台在＂后端应急指挥中心＂、＂现场应急指挥中心＂及＂移动指挥所＂等多个位置和场景下的建设目标和功能框架,并对平台设计与实现过程中可能涉及到的平台总体结构设计、平台软硬件及网络支撑环境、平台数据采集传输与共享模式等方面进行了简要描述。     

ADVANTAGES AND DISADVANTAGES OF REGIONAL SEWERAGE SYSTEMS1

ABSTRACT: A few years ago, many water quality administrators were convinced that large regional sewerage systems, consisting of one large treatment plant and long trunk sewers extending out to various communities, represented the only efficient and economical means of assuring water quality control. In communities favoring rapid development, the provision of sewer service and encouragement of development of new centers along the trunk sewers offered an additional advantage. More recently quite different points of view are arising in certain areas. In parts of New Jersey strong environmental and community resistance has arisen to proposed central plant-trunk sewer systems. The facilitation of new development along the trunk sewers is viewed as a menace by townships not wanting intensive development of these areas. The diversion of effluent flows to trunk sewers rather than septic tanks would dry up the streams which water quality programs are supposed to protect. Both sides to the controversy have mobilized engineering, environmental, economic, and legal expertise and some critical policy issues have developed. Reconsideration of regional sewerage management and particularly trunk sewer policy is required. The decision as to extent of sewerage service areas involves complex and sensitive planning issues. Because of potential conflicts of interest, such decisions should not be left to staffs of sewerage authorities and their design engineers.     

Risk assessment in a hypothetical network pipeline in UK transporting carbon dioxide

With the advent of Carbon Capture and Storage technology (CCS) the scale and extent of its handling is set to increase. Carbon dioxide (CO₂) capture plants are expected to be situated near to power plants and other large industrial sources. Afterward CO₂ is to be transported to storage site using one or a combination of transport media: truck, train, ship or pipeline. Transport by pipeline is considered the preferred option for large quantities of CO₂ over long distances. The hazard connected with this kind of transportation can be considered an emerging risk and is the subject of this paper.The paper describes the Quantitative Risk Assessment of a hypothetical network pipeline located in UK, in particular the study of consequences due to a CO₂ release from pipeline.The risk analysis highlighted that some sections of pipeline network cross densely populated areas. For this reason, some changes in the original path of the network have been proposed in order to achieve a significant reduction in the societal risk.