| 摘要 |
PURPOSE:To accurately detect a defect present at a longitudinal seam from inside by providing a pipeline, 1st and 2nd lateral seam detectors, an ultrasonic flaw detector, etc. CONSTITUTION:While a pig main body travels in the pipeline, the 1st lateral seam detector 21A detects the lateral seam 22 of the pipeline 5 and then a longitudinal seam detector 4A operates under the command of a controller 34. This operation is carried out as to another longitudinal seam detector until a longitudinal seam 6 is detected, and the position signal of the seam 6 is stored in a controller 34. Further, when the pig main body further travels and the 2nd lateral seam detector 23A detects the seam 2, an ultrasonic flaw detector 25A operates under the command of the controller 34. Then when the pig main body furthermore travels and the 3rd lateral seam detector 33A detects the seam 22, a flaw detector 25A begins to detect the defect of the seam 6 under the command of the controller 34 and the result is stored in the controller 34. Thus, the defect present at the seam 6 is detected. |
