关键词: 钢管, 漏磁, 无损检测, 纵向伤, 周向磁化

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