Research on the Method and Apparatus of Alternating Magnetic Flux Leakage Testing for Sucker Rod

Based on the principle of alternative current magnetic flux leakage testing, various kinds of surface defects in the sucker rod were detected under alternating magnetization by insert coil. It was indicated by experiment that the amplitude of signals was affected greatly by several parameters such as the depth of defect, excitation magnetization strength and lift-off distance. Finally, the influence caused by various kinds of parameters was analyzed. Because the alternating magnetization was induced in the sucker rod in the whole circumferential direction, the method has a good sensitivity to test pockmarks with the resulting in inspection for sucker rod under corrosive environment.