基于轴向漏磁检测技术，采用有限元方法结合牵拉试验对管道环焊缝的漏磁场进行分析。通过改变焊缝余高以及焊缝中心处椭球型凹坑缺陷的尺寸，得到了描述漏磁场特征的磁通密度分布曲线。结果表明，焊缝中心无缺陷时，漏磁信号呈典型的增厚型特征，且随余高增加，磁通密度径向分量峰峰值、轴向分量峰谷值均非线性增大；焊缝中心存在椭球型凹坑时，漏磁信号出现复合现象，即表现为外侧焊缝的增厚型与中心缺陷的减薄型漏磁信号的叠加，且随余高增加，焊缝处缺陷的减薄型信号特征减弱。相同缺陷在管壁、熔合区、焊缝中心处的漏磁信号依次减弱，说明同样缺陷在焊缝中心时最不易被检出，该结果与牵拉试验结果一致。

The magnetic flux leakage (MFL) characteristics of pipeline girth weld were analyzed using finite element method combined with the pull test based on axial magnetic flux leakage principle. By changing weld reinforcement and the size of ellipsoid defect in the center of weld, the magnetic flux density distribution curves were obtained. The results show that the magnetic field distribution of pipeline girth weld appears thickening-type characteristic when there is no defect in the weld center. The radial component peak-to-peak value and the axial component peak-to-valley value of magnetic flux density increase non-linearly. Magnetic flux leakage signals show the magnetic field distribution characteristics of the weld and the ellipsoid defect, that is, the superposition of the thickening by weld and the thinning by defect. Moreover, with the increase of weld reinforcements, the thinning type signal characteristics of the weld defect become weaker. The intensity of magnetic flux leakage signal for the same size defect follows the sequence as from strong to week:pipe wall, fusion zone and weld, indicating that the same defect is most likely to be detected in the weld center, which is consistent with the result of the pull test.