| 摘要 |
PURPOSE:To improve simultaneity of a flaw detecting signal and precision of flaw detection, by a method wherein a magnetic field, which absolute method detecting coils emanate, is utilized for differential method detecting coils, and a dummy coil, shielded with a metal ring, is connected to the absolute method detecting coil. CONSTITUTION:Absolute detecting coils 4, 25 and differential coils 2, 3 are coaxially located at a probe 1. The absolute detecting coil 4 is positioned in the proximity of the middle of the differential detecting ciols 2 and 3, and the absolute coil (dummy coil) 25 is placed at a position allowing it to be spaced enoughly away from the detecting coils 2, 3, and 4 and is shielded with a metal ring 26. As a result, a magnetic field, which the detecting coil emanates, does not reach a wall of a pipe 6 to be measured. If the probe 1 is inserted into a pipe 6 to be measured, the differential detecting coils 2 and 3 are influenced by the magnetic field, which the absolute detecting coils emanate, to detect a flaw detecting signal, and thereby the signals, transmitted by an absolute method and a differential method, are obtained simultaneously. Additionally, the change in temperture and an electrostatic capacity, can be removed, because an absolute detect coil (dummy coil) 25 is provided in the coil of the absolute detecting coil. |
