| 摘要 |
PURPOSE:To detect easily and exactly a position of a damaged part of a gas pipe, etc. to which asphalt covering is performed on its outside face, by connecting a buried pipe and an oscillator to a closed circuit by a current line laid on the ground. CONSTITUTION:A buried pipe 1 and an oscillator 3 are connected so as to form a closed circuit by a current line 5 laid on the ground, an AC current is made to flow to the closed circuit from the oscillator 3, and a current value of the line 5 is measured 6 along the line 5. In this way, a damaged position of asphalt covering performed to the outside face of the buried pipe 1 is detected in accordance with Ferranti phenomena. |
