基于概率统计埋地钢质管道剩余寿命的评估研究

对埋地管道压力管道进行了腐蚀剩余寿命的评估。通过随机检测管道表面的腐蚀凹坑深度,并采用概率统计的方法得到了管道最大腐蚀深度,然后参照ASME标准进行了管道的腐蚀剩余寿命评估,并得出结论。     

Probabilistic prediction of the residual lifetime of a gas pipeline under pitting corrosion

With the help of a deterministic formula and statistical simulation method, the residual lifetime distribution, numerical performance, and residual factors of gas pipeline reliability are determined for the case when the yield point, pressure, and sizes of pipe walls and defects are distributed according to the Gauss law. The optimal strategy is determined for preventing the failure of the examined gas pipeline, which minimizes emergency failure and increases gas pipeline safety.     

Statistical modeling of the residual life of an oil and gas pipeline under alternating pressure

According to a deterministic formula, using the method of statistical modeling, it was found that the residual life of an oil and gas pipeline has a lognormal distribution, where the input arguments: Paris’ coefficients, the annual number of cycles, the diameter and the pipeline wall thickness, the initial and critical crack depth, and the maximum and minimum stresses are subject to the normal law. According to these data, limiting safe operation lifetimes of the pipeline sections analyzed are determined.     

腐蚀海底管道剩余强度的可靠性模型及评估研究

为了制订行之有效的海底管道检修方案,有效地保障海底管道的安全运营,极有必要对腐蚀海底管道的剩余强度进行可靠性评估。本文首先阐述了海洋环境对海底管道腐蚀的影响因素,其次建立了腐蚀海底管道可靠性模型;同时还以某腐蚀海底管道为例,进行了可靠性评估,为海底管道的维护管理提供了科学的依据。     

基于灰色组合模型的管道腐蚀速率预测

预测管道的腐蚀速率对于预测管道的剩余寿命及剩余强度的变化趋势具有重要意义。神经网络预测方法需要已知腐蚀影响因素的测量数据，而获取这些数据的成本较大，因此，有必要提出一种新的预测方法以降低检测成本。将灰色系统理论、人工神经网络及时间序列分析方法相结合，建立灰色组合模型，通过对腐蚀速率测量数据序列的趋势性、周期性及随机性成分分别建模，从而实现对腐蚀速率的预测。实例表明，灰色组合模型的预测精度高于其它几种预测方法，具有推广价值。     

Monitoring stressed state of pipelines by magnetic parameters of metal

A method is described for assessing the residual life of pipelines and articles made of structural steels. Dependences between applied stresses and parameters of registered magnetic noises are shown. Criteria are suggested for assessing the in-service destruction of pipeline metal by its magnetic parameters.     

管道内地磁场特性分析及实验研究

将油气管道理想化为无限长的磁性材料圆柱腔,根据静磁场理论中的磁通连续性原理,分析了管道对地磁场不同方向分量的屏蔽系数,推导出油气管道内剩余地磁场强度与管道走向之间的关系,建立了管道内三轴磁传感器采集数据的数学模型,通过大量现场实验数据验证本模型.在管道走向检测领域具有重要意义,研究成果具有广阔的应用前景.     

含体积型缺陷管线表面应力应变状态的有限元模型分析及试验验证

腐蚀是影响油气管道安全运行的主要因素,确定预测腐蚀管道的剩余强度和其剩余寿命的方法有重要意义。应用ANSYS软件对含内腐蚀缺陷管道的三种模型进行有限元分析,得到采用1/4模型计算更简便、高效;由两种边界条件的模拟结果可知,自由边界条件下缺陷中心处的应变数值较高。管道外壁周向应变峰值分别与缺陷直径呈线性关系,与缺陷深度呈指数关系。并利用电阻应变片测量的值,与相同条件下模拟值的偏差不超过5.3%,结果表明,该建模方法是可靠的。     

减底渣油泵P-17/1出口弯头爆管失效分析

通过无损探伤、断口检验、电镜和能谱分析,以及机泵的状态监测等方法,对某车间减压塔底部渣油泵P-17/1出口管线开裂、弯头爆管进行了分析。发现该泵出口管线开裂、弯头爆管的主要原因有：首先在停车用蒸汽和水对管线进行清理时,未处理干净,管线中残存的硫、氯发生浓缩;其次在很小的区域安装4个不锈钢弯头,造成残余应力过大,在焊缝处形成应力腐蚀裂纹;第三由于机泵及相连管线的振动,裂纹进一步扩展,最后由于吹扫的压力,发生爆管。     

双腐蚀缺陷油气管道剩余强度分析

以X60双腐蚀缺陷油气管道为研究对象,借助ANSYS软件,分析双腐蚀缺陷半径和缺陷深度对其等效应力和剩余强度的影响。结果表明:随着轴向位置的增加,双腐蚀缺陷管道等效应力在屈服极限与抗拉极限之间变化;随着缺陷半径的增大,剩余强度呈增加的趋势,安全性增强;随着缺陷深度的增大,剩余强度呈减小的趋势,安全性降低。所得结论对于油气管道的腐蚀安全评价有一定的参考意义。     

影响管线钢应力腐蚀破裂的力学和材料因素

介绍了有关管线钢应力腐蚀破裂（SCC）的类型及特点，重点阐述了影响管线钢SCC的力学和材料因素。在力学方面，分析了管线的最大运行应力、压力波动R值（最小和最大压力的比值）、残余应力以及应变速率对SCC的重要影响。在材料方面，介绍了不同钢级管线钢的化学成分和显微组织，并对不同SCC形式下，材料的化学成分、显微组织对SCC行为的影响进行了讨论。     

加氢管线泄漏原因分析

采用宏微观形貌分析、渗透探伤、化学成分分析、显微组织分析、力学性能测试、EDS微区成分分析等手段,分析了20钢加氢管线泄漏的原因。结果表明:20铜加氢管线泄漏是因为管材存在锻造裂纹,该裂纹在焊接残余应力和工作应力的作用下扩展,同时管材内表面局部冲刷腐蚀减薄也加快了锻造裂纹的扩展,最后导致开裂。     

腐蚀管道的剩余强度评定及ANSYS二次开发

针对腐蚀管道对工作承压能力的影响,利用ANSYS软件建模仿真,通过与真实材料拉伸试验的数据对比,验证了有限元方法有较高的可靠性。进一步研究了内腐蚀缺陷尺寸对管道剩余强度的影响,并重点研究了相邻腐蚀缺陷相互作用和群腐蚀管道的评价方法。研究结果表明,管道的剩余强度会随着缺陷尺寸的增大而减小,相邻腐蚀缺陷在轴向和环向距离一定范围内会随着间距增大而相互影响减小。利用相邻腐蚀缺陷相互作用准则建立了等效简化群腐蚀的方法。为了解决ANSYS评定管道剩余强度操作的复杂性,开发了针对单个腐蚀和复杂腐蚀的评估软件。     

Estimation of the Residual Magnetic Field Strength Inside a Pipeline after Testing by a Magnetic Flaw Detector

The residual magnetic field strength inside a pipeline after testing by a magnetic flaw detector is calculated. A portable device for demagnetizing local joint-pipe sections in carrying out repair-welding works is proposed.     

Kinetics of edge crack in the field of residual stresses

A methodical approach and program for calculating the kinetics of flat crack extension with an arbitrary front configuration in the spatial elements of constructions have been developed. The technique creates possibilities to estimate cyclical growth and changes in the front configuration at an arbitrary distribution of stresses. The experimentally calculated method of estimating the crack dimensions has been stated. The example of calculating a crack in the pipeline in the presence of residual stresses and taking into account T stresses is presented.     

Estimating the reliability of elastically curved segment of gas pipeline using the criterion of crack growth resistance

In the framework of random number theory, a mathematical model describing the reliability of an elastically curved segment of a gas pipeline according to a crack growth resistance criterion for the case where the physicomechanical characteristics of the pipe steel, fracture strength, gas pressure, temperature drop through the wall, and radius of the elastic curve are distributed according to a normal (Gaussian) law is developed. According to this data we find the permissible sizes of cracklike defects under which the safety of operation and residual rated lifetime of potentially dangerous segments of a gas pipeline are guaranteed.     

A method for improving the accuracy of evaluating the dimensions of flaws in walls of tubular elements of structures

An algorithm for evaluating the real accuracy of the basic measuring instrument (exterior or in-tube flaw detector) in measuring parameters of flaws of a particular inspected tube was proposed on condition that the basic measuring equipment has no systematic error, while a verification instrument is considered as “absolutely” precise or “reference.” A statistical method of increasing the accuracy of evaluating the dimensions of flaws in thin-walled tube elements was developed on the basis of a correlation between the dimensions of flaw parameters. It can be taken as a basis for finding real values of parameters of flaws and for performing reliable calculations of the residual strength and residual life, for scheduling optimal periods for the next inspection of pipelines, and for ranging segments of a pipeline by a risk criterion, thus providing optimal scheduling of repairs.     

Sensor design and image accuracy for application of capacitance CT to the petroleum refinery process

Fluid catalytic cracking (FCC) catalysts are used to produce high-quality petroleum from residual oil by the contact cracking process in the petroleum refinery. The key point in producing high-quality petroleum from residual oil is uniform fluidization at the mixing point. The sensor for capacitance computed tomography (CT) is designed to visualize the powder concentration in the process of mixing air and FCC catalysts in a vertical pipeline. The concentration distribution images are obtained under certain air-catalyst parameter conditions. The relationship between the air-catalyst parameter condition and the powder distribution is analyzed in detail. Moreover, the accuracy of the reconstructed image is discussed systemically in terms of volume fraction, residual capacitance, and capacitance correlation.     

基于总体局域均值分解及稀疏表示分类的天然气管道泄漏孔径识别

针对天然气管道泄漏受孔径、传感器距离、管道内压力等多种因素影响,特征提取及识别算法较为复杂的问题,提出了基于总体局域均值分解-相对熵的特征提取算法并结合稀疏表示分类的泄漏孔径识别新方法。该方法采用总体局域均值分解方法对泄漏信号进行自适应分解,得到不同孔径泄漏信号的特征信息,并根据KL散度选择包含主要泄漏信息的PF分量,在此基础上提取多种时频特征参数,获取全面准确表征泄漏信号的特征向量;针对小样本复杂信号的分类,提出稀疏表示分类器实现泄漏孔径准确分类。该分类器采用过完备字典求得测试信号的最稀疏解,并以此解作为测试信号的稀疏重构系数,以获取测试信号在不同类别中的重构信号,最终通过判断测试信号与重构信号的残差值大小完成泄漏孔径分类。实验结果表明,所提出的算法比传统的SVM及BP分类算法识别准确率高。     

基于紧致插值方法对气动制动管路研究

紧致插值方法可用于气动制动管路中气柱状态的分析,考虑管路内的热交换和摩擦因素等影响,利用气体动力学原理建立管路的数学模型。通过一般迎风差分方法对管路进行分析后,再利用紧致差值方法对管路内气柱的状态进行分析,然后结合MATLAB软件进行仿真计算。研究表明：通过紧致插值方法研究气动管路中的重要参数,得出其状态值与理论值基本吻合,从而确保了该方法的可行性,为后续分析气动制动系统中管路部分的研究提供了基础。