Impact Damage Testing Study of Shanxi-Beijing Natural Gas Pipeline Based on Decision Tree Rotary Tiller Operation

The North China Plain and the agricultural region are crossed by the Shanxi-Beijing natural gas pipeline.Resi-dents in the area use rototillers for planting and harvesting;however,the depth of the rototillers into the ground is greater than the depth of the pipeline,posing a significant threat to the safe operation of the pipeline.Therefore,it is of great significance to study the dynamic response of rotary tillers impacting pipelines to ensure the safe opera-tion of pipelines.This article focuses on the Shanxi-Beijing natural gas pipeline,utilizingfinite element simulation software to establish afinite element model for the interaction among the machinery,pipeline,and soil,and ana-lyzing the dynamic response of the pipeline.At the same time,a decision tree model is introduced to classify the damage of pipelines under different working conditions,and the boundary value and importance of each influen-cing factor on pipeline damage are derived.Considering the actual conditions in the hemp yam planting area,targeted management measures have been proposed to ensure the operational safety of the Shanxi-Beijing natural gas pipeline in this region.

Use of community mobile phone big location data to recognize unusual patterns close to a pipeline which may indicate unauthorized activities and possible risk of damage

Damage caused by people and organizations unconnected with the pipeline management is a major risk faced by pipelines,and its consequences can have a huge impact.However,the present measures to monitor this have major problems such as time delays,overlooking threats,and false alarms.To overcome the disadvantages of these methods,analysis of big location data from mobile phone systems was applied to prevent third-party damage to pipelines,and a third-party damage prevention system was developed for pipelines including encryption mobile phone data,data preprocessing,and extraction of characteristic patterns.By applying this to natural gas pipelines,a large amount of location data was collected for data feature recognition and model analysis.Third-party illegal construction and occupation activities were discovered in a timely manner.This is important for preventing third-party damage to pipelines.

Analysis of Pipeline Damage to Impact Load by Dropped Objects

Marine pipeline damage subjected to dropped objects from platforms or supply vessels is analyzed to introduce an easy and applicable approach to investigating the damage induced by impact load from drop weight. A practical engineering example was presented and analyzed using the commercial program 'ANSYS/LS-DYNA', which is a powerful tool with an explicit dynamic solver. And rational agreement of the results with previous works was obtained. The suggested procedure might be taken as a checking analysis of the protection measures of pipelines in addition to the general risk assessment method.

Probabilistic Model of Cumulative Damage in Pipelines Using Markov Chains

This paper presents a probabilistic model of cumulative damage based on Markov chains theory to model propagation of internal corrosion depth localized in a hydrocarbons transport pipeline. The damage accumulation mechanism is unit jump type, depending on the state. It uses a shock model based on Bernoulli trials and probabilities to remain in the same state or the next one. Data are adjusted to Lognormal distribution and proven with a Kolmogórov-Smirnov test. The vector obtained from multiplying the initial state vector with the transition matrix was developed and the system of equations to find each transition probability with a single inspection report was solved. In order to calculate propagation of internal corrosion after inspection, an exponential equation was proposed and a parameter was adjusted to the data. Time to expected failure was obtained by adding the time expected in each damage state. Each time step was adjusted to real time.

Research of Risk Identification and Prevention of Underground Pressure Pipelines Damage Caused by External Disturbance

External disturbance is an important cause of underground pressure pipeline damage,which leads to accidents,and it is crucial to study the risk of damage caused by external disturbance and come up with proper prevention and control measures.We reviewed literature on risk identification of underground pressure pipelines damage due to external disturbance was conducted,and a list of risk factors was formed.Based on the list of risk factors,fault tree analysis was carried out on underground pressure pipelines damage caused by external disturbances,and risk prevention and control measures were proposed through the calculation of minimum cut sets,minimum path sets,and structural importance,in hopes of providing reference for the normal operation of underground pressure pipelines.

Study on Interaction Relationship for Submarine Pipeline with Axial Corrosion Defects

Corrosion is one of the main reasons to cause the operation accident of submarine oil and gas transmission pipelines. As the major corrosion pattern in submarine pipelines, the effects of corrosion clusters consisting of the adjacent corrosion defects on failure pressure are investigated through non-linear large-deformation finite element method. Typically, the failure behavior and limit strength of submarine pipeline with axial groove- groove corrosion defect pair exposed to interhal pressure are analyzed. The effects of corrosion depth and axial spacing between a pair of corrosion defects on failure pressure are concluded. An interaction relationship for corrosion defects in pipelines, as well as prediction formulations for assessing the remaining strength of corroded pipelines are proposed. The expressions based on the proposed interaction relationship give more accurate results than the methods used in the existing design guidelines.

Sendai Water Pipeline Response to the 2011 Tohoku Earthquake

Damage caused by the 2011 Tohoku Earthquake （Mw 9.0） to transmission and distribution pipelines in Sendai City is summarized. The locations of the pipeline repairs are discussed relative to earthquake intensity, geomorphologic conditions and landform change in the developed areas of hilly land. Repair rate （repairs/km） is summarized according to pipe material and presence or absence of artificial landform change. The following findings were obtained： （1） More than 80% of the repairs took place in pipelines installed in higher lands such as hill and terrace areas consisting of hard soils; （2） Nearly all the pipe repairlocations in hill areas are where landform change was made through land development tor residential purposes over me past several decades; （3） The aforementioned repair rate was more than 3.6 times than that of other lowland areas where no landform change occurred. The heaviest concentrations of pipe repairs of vinyl chloride pipes and ductile iron pipes were observed within the boundary area between cutting and filling, having a thickness between -2.5 m and 2.5 m. Approximately 78% of the all pipe repairs occurred outside of areas where severe ground failures took place. A mechanism of pipe damage in the areas free of severe ground failure was discussed.

冲击载荷下含腐蚀缺陷的海底管道损伤分析

针对海底油气管道因冲击和腐蚀易造成管道损伤破坏的问题,基于耦合欧拉-拉格朗日算法(CEL)建立坠物-腐蚀管道-海床土体冲击有限元模型,分析了坠物质量、速度、埋深和腐蚀深度对含腐蚀缺陷管道损伤的影响,并与未腐蚀的完整管道进行了对比。以此为基础,分析了内压和腐蚀深度对撞击后的腐蚀管道应力的影响规律。研究结果表明:含腐蚀缺陷管道受冲击损伤程度均大于完整管道,同等撞击速度、质量和埋深下,冲击损伤值最大分别相差68.6%、14.3%和194.7%;撞击后的腐蚀管道和完整管道最大等效应力均随内压增加而增大,同等内压等效应力值最大相差50.4%;同等腐蚀深度下,未撞击腐蚀管道和撞击后腐蚀管道等效应力值最大相差11.7%。这表明海底油气管道冲击损伤分析应考虑腐蚀缺陷的影响。研究方法及结果可为海底油气管道冲击损伤分析与评价提供参考。

积石山6.2级地震供水系统震害调查与分析

2023年12月18日甘肃省积石山县发生6.2级地震,造成当地各类工程结构发生不同程度的破坏,导致了重大人员伤亡。基于调查资料,总结了供水系统中的建(构)筑物、设施设备和供水管网的震害特征。研究表明:经过正规抗震设计和施工的建筑物震害较轻,表明我国抗震设计规范发挥了积极作用;低烈度区水厂设施设备因地震破坏而停运,个别设备漏油污染了水质,进而导致了供水能力下降;位于高烈度区的供水管网在老旧钢质管道连接处发生多处破坏,出现了水量不足、水压降低的情况,给居民生活造成了不利影响。最后,从采取设备减隔震技术、管道和设备接口采用柔性连接、选择供水管道材质、全面开展管网漏损排查等四个方面提出了恢复重建的建议。

基于MMC韧性断裂准则的X80管道凹陷损伤程度分析

为提高管道凹陷安全评价的准确性,将修正Mohr-Coulomb(Modified Mohr-Coulomb, MMC)韧性断裂准则应用于管道损伤评价中,建立了球形压头压入管道表面的凹陷受损有限元模型,并结合ABAQUS-VUMAT实现了凹陷受损区域损伤值可视化。精确分析了不同凹陷深度下X80管道的内压和凹陷尺寸对凹陷处损伤值的影响。结果表明:凹陷深度值较浅时,最大损伤值位于管道凹陷处内表面中心。随着凹陷深度的增大,最大损伤值位置由中心向四周转移;凹陷深度越深、管道内压越大、凹陷尺寸越小,管道损伤值越大;当凹陷深度超过12%D时,随着凹陷深度的增加,管道内压越大、凹陷尺寸越小,损伤值增长速率越大。

空调冷凝器管道激光超声导波跨能量层级映射迁移检测方法

空调冷凝器是空调设备的关键部件,其弯管连接部位由于损伤类型多和几何形状复杂等原因造成传统接触式损伤检测手段难以应用,本文提出一种基于能量映射迁移网络的非接触式激光超声导波无损检测方法。首先,通过小波分解提取烧蚀信号和热弹信号的概貌波形,设计自编码能量映射函数将热弹信号特征空间映射到烧蚀信号特征空间,获得更接近烧蚀信号特征的映射热弹信号。其次,通过能量映射迁移网络对齐映射热弹信号和烧蚀信号特征空间,将网络模型中的域转换误差和样本标签误差之和用作特征空间对齐误差值。最后,对空调冷凝器泄漏、分层和裂纹等损伤进行检测实验验证所提新方法性能,结果表明其损伤识别精度为93.09%,比传统激光热弹激励检测方法提高了7.23%。

基于神经网络的高压蒸汽管道损伤识别

核电站高压蒸汽管道存在诸多问题,对他进行结构健康监测至关重要。文中以某核电站高压蒸汽管道为研究对象,建立缩比模型,结合有限元模型更新方法和BP神经网络进行损伤识别。通过管道模态采集试验获取结构特征参数,更新有限元模型,使他与实际管道结构在动态响应上相似。利用BP神经网络对损伤工况进行识别,选取合适的参数进行训练。结果表明训练后的神经网络在损伤识别中具有高准确率,证明了该方法的可靠性,为实际管道结构的损伤识别积累经验。

基于混频非线性超声的金属压力管道早期疲劳损伤检测

压力管道在服役过程中由于受载荷波动等因素的影响容易产生疲劳损伤,疲劳损伤的累积会导致管道失效。本文针对金属压力管道早期疲劳损伤的检测问题开展研究,提出了基于混频非线性超声的疲劳损伤检测方法,设计了混频非线性超声检测装置,开展了304不锈钢试样的疲劳损伤检测实验,建立了疲劳损伤程度与混频非线性指数之间的联系。在此基础上,开展了304不锈钢管道疲劳损伤的在线检测实验,结果表明,在疲劳加载过程中管道应力集中部位的混频非线性指数的增长速度明显高于其他部位,证实了混频非线性超声检测方法可用于金属压力管道早期疲劳损伤的检测与评估。

基于周向SH导波的钢制环氧套筒胶结缺陷检测方法研究

钢制环氧套筒目前已在油气管道损伤修复领域得到广泛应用,其树脂层的胶结质量对管道修复后的补强效果至关重要。对此,本文提出了基于电磁超声周向SH导波的钢制环氧套筒胶结缺陷检测方法。首先,通过建立有限元模型研究了周向SH0模态导波在钢制环氧套筒结构中的传播特性;其次,采用有限元仿真与实验研究相结合的方式探究了周向SH0模态导波检测钢制环氧套筒胶结层内预制的阶梯型贯穿空腔缺陷的可行性。仿真和实验结果均表明,SH0模态直达波幅值与空腔宽度基本呈线性正相关,说明该方法可实现对胶结层中贯穿型空腔缺陷的检测,并且可区分空腔大小,验证了所提方法用于检测钢制环氧套筒胶结缺陷的可行性。

输氢腐蚀管道在轴向拉伸应力与内压共同作用下的失效压力研究

为评估内压和轴向拉伸应力共同作用下含腐蚀缺陷的氢气管道安全状况,基于Abaqus构建1种三维有限元模型,利用X100管线钢在不同充氢时间下的机械性能,模拟管道的氢损伤程度。研究确定部分参数效应,即轴向拉伸应力、氢损伤和缺陷几何形状。研究结果表明:轴向拉伸应力、内压、腐蚀和氢损伤的协同作用可导致管道失效压力显著降低;失效压力随着氢损伤、轴向拉伸应力、缺陷长度和缺陷深度增加而减小;缺陷区域的应力分布受到轴向拉伸应力、腐蚀缺陷长度和深度的影响,但在正常工作条件下(即内压为10 MPa)却不受氢损伤影响。研究结果有助于更好地理解氢气传输管道的失效行为,从而优化氢损伤情况下的管道设计和完整性管理策略。

航空液压管路高低周复合疲劳寿命预测研究

为有效预测航空液压管路的疲劳寿命,在分析现有液压管路寿命预测方法不足的基础上,针对飞机液压管路受力特点,分析了液压管路的载荷类型,并对其进行了载荷分解,进而提出了一种基于高低周复合载荷的疲劳寿命预测方法。为验证所提方法的有效性,以某型航空液压管路为例,利用Ansys Workbench软件对其进行仿真分析,在此基础上,对所分析液压管路分别进行了考虑高低周载荷作用和不考虑高低周载荷作用的疲劳寿命预测。对比寿命预测结果发现,高低周复合疲劳载荷对液压管路的寿命影响较大,在预测液压管路的疲劳寿命时,需同时考虑高周疲劳载荷和低周疲劳载荷的作用。

大型变电站消防栓给水管道断裂原因

某大型变电站消防栓给水管道发生断裂。采用宏观观察、化学成分分析、扫描电镜分析、金相检验、力学性能测试及强度校核计算等方法对管道断裂的原因进行分析。结果表明:管道沟槽接头的滚槽工艺不当,使管道内壁沟槽边缘出现严重的机械损伤,破坏了基体的连续性,并产生较大的应力集中;管道组织中存在大量游离态渗碳体,使材料脆化,降低了材料的抗滚压加工开裂能力;管道及沟槽接头装配不规范,在管道与弯头连接的卡箍边缘形成了较大的弯曲力矩,内壁机械损伤部位萌生裂纹并扩展,最终导致管道断裂。

埋地管线破损漏土诱发地面塌陷过程的流固耦合离散元模拟

为了探究埋地管线破损-漏土诱发地面塌陷的规律,采用DEM-CFD方法,综合考虑管线埋深、水压和破损口半径等因素,对单一砂土层和上覆黏土层两种工况的地面塌陷过程进行了数值模拟分析。结果表明:颗粒损失率和地面沉降值呈正相关关系;根据颗粒损失速率,塌陷过程可划分为颗粒运移、快速损失和沉降槽缓慢扩展3个阶段;水压是影响颗粒损失速率的主要因素;对于单一砂土层,随着水压、破损口半径的增大和管线埋深的减小,颗粒损失率逐渐增大;对于上覆黏土层,由于颗粒的黏结作用,颗粒运移阶段持续时间与上覆黏土层厚度呈正相关关系,与水压、破损口半径呈负相关关系。

交直流混合干扰下涂层破损X70钢腐蚀特性研究

油气管道经过电气化铁路和高压输电线路易出现交直流混合干扰腐蚀现象。针对目前交直流混合干扰下涂层破损管道的腐蚀行为研究尚不充分的情况,采用失重、电化学试验,并结合光学显微镜、激光光谱共聚焦显微镜、X射线衍射(X Ray Diffraction,XRD)等检测手段,开展了微小涂层破损X70钢在交直流混合干扰下的腐蚀特性研究。结果表明:(1)相同电流密度下试样最大腐蚀坑深度由深到浅排序为:涂层破损直径D=5 mm试样、D=2 mm试样、D=1 mm试样、无涂层试样;(2)存在临界电流密度,当i<120 A/m^(2)时,随电流密度的增加最大腐蚀坑深度缓慢增加,当i≥120 A/m^(2)时,随电流密度的增加最大腐蚀坑深度急剧增加;(3)当i=180 A/m^(2)时,D=5 mm试样腐蚀深度达1883.18μm,涂层破损直径由原来5 mm扩展到7 mm。

液氢管道在线检测技术分析

液氢管道在液氢输送、储存、加注等环节发挥着不可替代的作用,管道运行期间,定期检验是保障其安全使用的必要手段。鉴于其内外管全封闭结构的特殊性,液氢管道唯有采用在线检测。依据在役液氢管道的失效和损伤模式分析,梳理了液氢管道的在线检测技术。对目前常用在线检测技术的适用性进行分析后发现,射线数字成像检测技术(DR)是液氢管道内管焊缝检测的最优选择。开展含缺陷内管的双层管试件DR检测试验,证明液氢管道DR在线检测技术具有可行性和有效性。