钢质管道缺陷地面漏磁场定量表征方法与实验研究

Many oil and gas pipelines are unavailable to take internal inspection techniques to find out the pipeline defects, such as corrosion defects and crack. Thus, the defects in such pipelines are hard to be detected and impose a negative effect on safety of pipeline operation. A few techniques, like mental magnetic memory testing, are able to achieve quick detecting to mental damage caused by stress concentration, but cannot be used on the ground. Also, the features of defects cannot be identified effectively. According to the physical mechanism of ground leakage magnetic field and the characteristics of three-component magnetic field gradient in pipeline defects, this project will carry out experimental research, theoretical analysis and numerical calculation. The study focuses on the mechanism of ground leakage magnetic field, the forward and inverse method used to research the quantitative characterization in such defects. First, based on the metal magnetic memory theory, the magnetic mechanical effect and the microscopic physical mechanism of ground leakage magnetic field, the defect - stress - magnetic coupling relationship is put forward. Then, some factors, such as the type and size of the defects, the pipe location, depth, distance between two test sensors, which influence the distribution of ground leakage magnetic field, are considered through experiments. Last, by analyzing the features of waveforms and using the typical waveforms for defect inversion, the inspecting and qualitative parameters of the defects can be achieved. Through research projects, the type of defects can be effectively identify, which has an essential impact on the development of non-contact defect detection technology and the safety and integrity of the pipeline.

许多不能开展内检测的油气管道中形成的腐蚀与裂纹等缺陷直接影响安全运行，金属磁记忆检测等技术虽然可以实现应力集中造成损伤的检测，但其不适用于埋地管道的地面检测，并且不能有效识别出缺陷特征。本项目将针对缺陷的地面漏磁场物理形成机理及地面三分量磁场梯度特征开展实验研究、理论分析和和数值计算；重点研究缺陷的地面漏磁场形成机理、定量化表征与正反演方法。首先，利用金属磁记忆理论、磁机械效应与漏磁场形成微观物理机理，研究缺陷-应力-磁耦合关系；其次，实验系统研究缺陷类型、尺寸、管道位置、埋深、检测传感器距离等对地面磁场分布梯度的影响；在此基础上，识别缺陷地面漏磁场的波形特征，进而利用典型波形进行缺陷反演，实现地面非接触磁检测与定量化参数表征。通过项目的研究可实现管道缺陷的有效识别，对促进缺陷非接触式检测技术的发展以及保证管道本质安全与完整性具有重要意义。

为了实现非内检管道连续的非接触检测和判断，来真实反映管道整体的非连续性金属损失及超过标准的应力集中情况，针对铁磁管道缺陷的地面漏磁场物理形成机理及地面三分量磁场梯度特征开展了实验研究、理论分析和和数值计算；重点研究了管道缺陷应力增加的地面漏磁场形成机理、影响因素以及定量化表征方法。首先，利用金属磁记忆理论、磁机械效应，揭示了管道缺陷力磁基本关系与地面漏磁场形成微观物理机理；其次，通过实验研究确定了缺陷尺寸、管道位置、埋深等对地面磁场分布梯度的影响规律；有效识别出管道缺陷地面漏磁场的波形特征，利用典型波形进行了缺陷反演，实现了地面非接触磁检测与定量化参数表征。本项目建立了复杂应力条件下铁磁管道力磁耦合模型，以及油气管道缺陷-磁异常间的正演、反演模型，提出了埋地钢质管道腐蚀、裂纹等典型缺陷的磁异常特征参数；通过自主创新研制出管道应力非接触式磁应力检测系统与在线监测系统；在此基础上，形成了埋地管道缺陷非接触式磁应力现场检测方法，已在国家管网干线天然气管道中得到了应用。可实现管道缺陷的有效识别，促进了管道缺陷非接触式检测技术的发展，直接服务于国家能源的安全供应。