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.     

页岩气井下开采管路气固耦合振动特性分析

页岩气开采过程中,井下管路内气体与管路的耦合作用,会引起管路振动,这是此类管路振动失效的主要原因。管路振动响应特性与井下管路长度、气体流速及压力等参数有直接关系,因此,研究这些参数的影响对揭示页岩气管路振动规律,提高井下管路安全性及寿命有重要意义。针对页岩气井下管路,在ADINA软件平台中建立有限元分析模型,进行振动模态分析,研究管路长度、气体流速及压力对管路气固耦合振动特性的作用规律。研究结果为页岩气井下管路振动实验研究提供理论指导,同时为气固耦合振动特性研究奠定基础。     

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。     

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.     

基于概率断裂力学的管道失效分析

针对油气管道的断裂失效模式以及失效分析过程中存在的不确定性，结合概率断裂力学和安全评定规范，提出了管道缺陷失效概率计算方法。根据主要评定参数：缺陷尺寸、工况栽荷、断裂韧性、机械强度的分布特征，对各随机变量模拟抽样，应用Monte Carlo数值计算方法确定管道上各缺陷的失效概率。可靠性失效评定方法确实反映了评定参数客观存在的不确定性，克服了确定性失效评定方法的缺点，具有极高的应用价值。     

Probabilistic forecasting for life of a cross-country gas pipeline under stress-corrosion damages

The life distribution and reliability indices for a cross-country gas pipeline under stress-corrosion are determined by a determinate formula with the use a static modeling method. As a result, the optimum planned replacement interval for the damaged gas pipeline that eliminates its crashes is established.     

天然气管道开裂失效分析

摘要：对发生开裂的天然气管道进行了系统的分析与测试,如宏观分析、成分分析、金相组织分析、硬度测试、氢含量测试、扫描电镜观察等。结果表明,管道开裂的机理为氢致开裂,管道局部的划伤是管道发生开裂的主要原因。     

Failure probability of corrosion pipeline with varying boundary condition

This paper presents the effect of external corrosion, material properties, operation condition and design thickness in pipeline on failure prediction using a failure probability model. The predicted failure assessment for the simulated corrosion defects discovered in corroded pipeline is compared with that determined by ANSI/ASME B31G code and a modified B31G method. The effects of environmental, operational, and random design variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress and pipe thickness on the failure probability are systematically studied using a failure probability model for the corrosion pipeline.     

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。     

天然气输送钢管研究与应用中的几个热点问题

全面阐述了天然气输送钢管研究与应用中的热点问题：高压输送与高钢级管线钢的研究开发;抗HIC管线管及其技术条件;富气输送及其对钢管性能的要求;直缝埋弧焊管和螺旋缝埋弧焊管的比较与选择;输气钢管延性断裂的止裂;管线在近中性pH土壤环境中的应力腐蚀开裂;管线管的残余应力及控制;高强度管线钢的屈强比问题;在役管道的适用性评价及风险管理等。     

20G钢输气管线腐蚀失效研究

针对某20G钢输气管线腐蚀穿孔失效,对管线失效特征和腐蚀环境特征进行了分析,试验研究了20G钢的组织结构、腐蚀速率及腐蚀产物,探讨了20G钢与环境介质的相互作用.结果表明:腐蚀失效发生在沟壑积液处;20G钢是铁素体和渗碳体的复相组织,晶粒粗大,在液相中具有较高的腐蚀破坏风险,CO2和Cl-是影响腐蚀的主要因素,腐蚀速率...     

天然气配气管网定量风险分析

天然气作为一种清洁环保的能源，需求量越来越大。提高天然气管网运行的安全性是一个至关重要而且必须解决的问题。风险评价技术是一种有效的安全评价模式，已成功地应用于油气管道的安全性评价。本文采用管道失效的历史数据分析与专家评价相结合的方法，计算天然气管道的失效率，并考虑穿孔和破裂两种失效形式所产生的后果，对天然气管道的风险进行了定量评价，并针对铸铁管进行了详细的案例分析。     

基于Lyapunov稳定性理论的气体管道泄漏检测技术研究

管道泄漏检测技术已经在长输气体管道安全运行中起到很重要的作用.本文讨论了基于李雅普诺夫稳定性理论的天然气管道泄漏检测技术,建立了气体管道泄漏动态模型,根据李雅普诺夫意义下对非线性系统的稳定性定义,通过对特征值的分析判断泄漏.实验仿真证明该方法具有一定的可行性.     

Structural features of crack formation during corrosion cracking

Stress corrosion cracking (SCC) causes damage to main gas pipelines due to formation and development of cracks on the outer surface of a tube. Prevention of SCC crack development and fracture of a gas pipeline is an important problem of diagnostics that can be solved in various ways. The most effective approach involves systematic use of in-tube nondestructive testing and local testing in shafts, owing to which the position of a flaw and its linear size are determined. The hazard of the flaw (residual life of a tube with cracks) is found and a decision is made about the necessity and methods of flaw repair, such as cutting out the tube, grinding the flaw, and reinsulating the tube surface, and the date of repeated nondestructive testing is set. These measures ensure timely discovery of potentially hazardous flaws and make it possible to take the necessary steps for preventing development of SCC.     

Monte-Carlo法计算含缺陷油气输送管线的失效概率

利用Monte-Carlo方法全面分析了裂纹深度、裂纹深长比、断裂韧度、屈服强度和输送压力等主要随机参数对含裂纹长输油气管线结构的失效概率的影响。利用故障树分析中的参数敏感性方法确定了随机参数的敏感性。计算结果表明,断裂韧度和裂纹深度对结构的失效概率影响较大,裂纹深长比对结构的失效概率也有重要影响。此外,还分析了焊接接头在不同的裂纹深度下,强度匹配对失效概率的影响,并还给出了管线在不同的失效模式下的年失效概率。     

Calculation of the reliability of the beam segment of a gas pipeline according to the stiffness criterion

A mathematical model for estimating the reliability of an aboveground beam segment of a gas pipeline according to the stiffness criteria has been developed in the framework of the Gaussian distribution of random quantities. The expected value of the gas pipeline wall thickness according to the predetermined reliability is determined that depends on the ratio between the expenditures for scheduled and emergency replacements.     

A marker system of equipment for nondestructive testing of gas main pipelines

Contemporary means of in-tube nondestructive testing are passed through a gas pipeline during its exploitation. In-tube pig flaw detectors are passed under a gas pressure from the launching to the receiving chamber for diagnostics of the gas pipeline. For some reasons, the pig flaw detectors are stuck in the gas pipeline. The marker system is designed not only for searching for a stop of a pig flaw detector on the route, but also designed for additional topographic referencing of the in-tube equipment for nondestructive testing during diagnostics of a gas pipeline.     

排污阀螺纹失效分析

针对西气东输管线中某处阀室排污管线上排污阀的螺纹失效,进行了宏观形貌、材质化学成分、金相组织、扫描电镜等失效分析工作。结果表明,堵头硬度、强度过低是导致排污阀螺纹失效的主要原因,提出了解决方案。通过淬火加适合的高温回火工艺,获得主要以回火索氏体为主要组织组成的显微组织,使硬度合适。通过高温扩散退火消除铸造组织形态,并细化晶粒,提高材料的强韧性。     

含缺陷高压管道复合材料补强有限元模拟

针对输气管道存在缺陷时容易引起气体的泄漏,利用高压管道复合材料补强力学模型,用有限元方法计算了在不同管道尺寸、厚度、缺陷面积和缺陷深度下用复合材料补强的最小层数,并绘出了补强厚度与缺陷面积和深度的关系图。计算结果表明,在极限输送气压下,缺陷深度和面积是决定补强层数的主要因素。     

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。