FLAW DETECTOR FOR HEATING TUBE

PROBLEM TO BE SOLVED: To enhance detection accuracy of the depth of flaw by making uniform a split detection coil, limiting the spread of the electromagnetic field distortion distribution of the flaw in a heating tube and suppressing the effect of a flaw part on the circumferential split detection coil. SOLUTION: A flaw detection probe 3" comprises a detection coil 2" and an exciting coil 1 held in a probe case 6 at an interval equal to or longer than two times of the diameter of a heating tube 4. The detection coil comprises two sets of split detection coil 9A, 9B, each comprising element coils split at least into four in the circumferential direction, arranged in two rows wherein the circumferential angle of the two sets of split detection coil is shifted such that the circumferential center of the element coil is matched with the circumferential end of the other element coil. Electromagnetic shielding boards partition respective element coils of the two sets of split detection coils 9A, 9B from each other and from the probe core.