Abstract:

In MFL testing with helical motion of steel pipes, the higher detection speed required longer detection sensor array, which made the covering area of the sensor array exceed the uniformly magnetized area. The signals obtained by each sensor of the sensor array will be different from each other in this case. For the restriction of detection speed and precision in longitudinal defect detection of steel pipes, the signal consistency in high speed MFL testing was studied. The influences of magnetic pole shoe structure on the uniformity of magnetic field on pipe surface were analyzed by finite element simulation as well as experiments.Based on the analysis, a magnetization method for MFL testing of longitudinal defects was proposed. The uniformly distributed magnetization zone on pipe surface is increased in this method. And the signal consistency becomes better for the same detection zone.

Key words: steel pipe, magnetic flux leakage(MFL), nondestructive testing(NDT), longitudinal defect, circumferential magnetization

摘要：

在钢管螺旋推进漏磁检测扫描中,检测速度越快,要求的检测探靴轴向长度越长，使得扫描覆盖范围超出了均匀磁化区,出现信号不一致的问题。针对钢管纵向伤检测中检测精度与速度相互制约的问题，以保证钢管纵向伤高速检测的信号一致性为目标，采用有限元仿真与实验验证相结合的方法，分析了周向磁化中磁极靴的结构对钢管表面磁场均匀性的影响。在此基础上提出了一种纵向伤漏磁检测磁化方法,扩大了钢管表面的均匀磁场区域，在同样的检测区域内提高了检测信号的一致性。

关键词: 钢管, 漏磁, 无损检测, 纵向伤, 周向磁化