APPARATUS AND METHOD FOR EDDY CURRENT FLAW DETECTION

PROBLEM TO BE SOLVED: To provide an eddy current flaw detection method and an eddy current flaw detection apparatus capable of heightening a S/N ratio by reducing detection noise and improving accuracy in defect detection. SOLUTION: The eddy current flaw detection apparatus includes an eddy current flaw detection sensor 5 having exciting coils 7A-7D arranged at regular intervals in a circumferential direction of a heat-exchange tube 1 in such a way that the axial directions of the coils may be approximately perpendicular to a surface to be inspected of the heat-exchange tube 1 for inducing an eddy current in the heat-exchange tube 1 and detection coils 8A -8D each arranged between the exciting coils 7A-7D in such a way that the axial direction of the coils may be along the axial direction of the heat-exchange tube 1 for detecting changes in the eddy current induced in the heat-exchange tube 1. The eddy current flaw detection apparatus includes a voltage regulator 12 for making the amplitude of a voltage to be applied to the exciting coils 7A-7D different from one another in such a way that detection noise in detection signals of the detection coils 8A -8D due to a deformed part 1c of the heat-exchange tube 1 and a tube plate 2 may be reduced. COPYRIGHT: (C)2009,JPO&INPIT