针对石油化工行业中压力管道的运行特点，根据漏磁检测原理开展了管道外漏磁检测。首先利用有限元分析软件建立了双励磁结构管道外漏磁检测模型，得到了半球形缺陷漏磁场的空间分布特性。然后研究了缺陷体积、管道壁厚、气隙厚度、两磁化结构张开角度等因素对缺陷漏磁信号的影响规律，并进行了试验验证。试验结果与仿真结果均表明，缺陷漏磁场磁通密度随缺陷体积的增大而增大，随管道壁厚和气隙厚度的增加而减小；缺陷漏磁场磁通密度轴向分量随着磁化装置张开角度的增加而变小。试验所用的漏磁检测装置能够有效地识别半球形缺陷，并能够对半球形缺陷进行量化和定位。

In view of the operating characteristics of pressure pipelines in the petrochemical industry, research on magnetic flux leakage outside the pipeline is carried out according to the principle of magnetic flux leakage detection. The finite element analysis software was used to establish a magnetic flux leakage detection model for the double-excitation structure pipeline, and the spatial distribution characteristics of the magnetic flux leakage of the hemispherical defect were obtained. The influence of the defect volume, pipe wall thickness, the value of the air gap, the opening angle of the two magnetized structures and other factors on the magnetic flux leakage signal of the defect were studied, and experimental research was correspondingly conducted. Both test results and simulation results show that the magnetic flux density of the defect leakage field increases with the increase of the defect volume, and decreases with the increase of the pipe wall thickness and the air gap; the axial component of the defect leakage field magnetic flux density decreases with the increase of the opening angle. The magnetic leakage detector can effectively identify hemispherical defects, and can quantify and locate the defects.