| 摘要 |
PURPOSE:To detect only the coupling part of a pipe in the inside of the pipe with other branch pipes and the like being distinguished, by running a truck, on which at least two or more magnetic sensors are provided radially with respect to the axis of the pipe, in a plane perpendicular to the axis of the metal pipe. CONSTITUTION:As magnetism sensors, e.g., eddy current sensors S1-S3 are radially attached on a truck 2 so that the sensors are positioned on the same circumference in a metal pipe 1. Towing ropes 5 and 6 are wound around winches 7 and 8, and the truck 2 is moved in the metal pipe back and forth so as to search a coupling part. At the position of the opening part of the branch pipe, which is provided at a part of the metal pipe 1, the detected outputs are not yielded from the two or more of the sensors S1-S3. At the coupling part, however, since a gap is formed along the entire circumference of the metal pipe 1, the detected outputs are yielded from all the sensors S1-S3. Therefore, only the coupling part can be recognized. |
