管道弱磁检测技术的有限元仿真

Finite element simulation of weak magnetic detection technology for pipelines

为减小漏磁检测器的体积,提高内检测的灵活性,采用有限元分析方法,在非磁饱和环境下,建立漏磁检测有限元模型,研究弱磁励磁对漏磁检测结果的影响,并对弱磁检测精度、信号特征和分布规律进行分析。结果表明：弱磁法具有一定的检测能力,但检测精度降低40%;管道缺陷深度在30%~40%壁厚范围内,外缺陷的径向弱磁信号不可区分;缺陷宽度小于2 mm时,外缺陷弱磁信号轴向分量幅值大于内缺陷信号幅值。该仿真结果可以作为内外缺陷评判的依据,同时对改进检测器结构具有参考价值。

To reduce the volume of magnetic flux leakage detector and enhance flexibility of inline inspections, the finite element analysis method is used under non-magnetic saturation conditions to construct the finite element model for detection of magnetic flux leakage and then determine impacts of weak magentic excitation to detection of magnetic flux leakage. In addition, detection accuracy, characteristics and distribution laws of weak magnetic signals are analyzed. The results show that the weak magentic technology can be used for detection, but with accuracy reduced by about 40%. For pipeline defects with depths at 30%-40% of wall thickness, radial weak magentic signals of external defects are undistinguishable. For defects with widths less than 2 mm, amplitudes of axial components of weak magnetic signals of external defects are lower than those of internal defects. The simulation results may serve as criteria for determination of internal or external defects. In addition, these results may provide valuable guidance to improve structure of detectors.