EDDY CURRENT FLAW DETECTION METHOD AND APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an eddy current flaw detection method and an eddy current flaw detection apparatus capable of reducing the effects of noise sources on the close-range side and the far-range side and detecting crack signals. SOLUTION: An eddy current flaw detection sensor 14 is cylindrical, and two exciting coils 1A and 1B and at least one detection coil 2 are arranged on its side surface in such a way that the direction along the winding of the detection coil 2 may be matched with the circumferential direction of the eddy current flaw detection sensor. An eddy current flaw detector 13 applies a first exciting frequency f1 reduced to an amplitude capable of ignoring tube noise and a second exciting frequency f2 of a frequency higher than the first exciting frequency f1 to the eddy current flaw detection sensor 14. The phase and gain of a measured waveform of the second exciting frequency f2 are adjusted so as to remove tube noise on the basis of an induced voltage detected by the detection coil 2 to obtaine a difference waveform between the first exciting frequency f1 and the second exciting frequency f2. COPYRIGHT: (C)2009,JPO&INPIT