| 摘要 |
PURPOSE:To make it possible to detect the welded part position of a metal pipe from the inside, by sending an electromagnetic induction type detector into the metal pipe. CONSTITUTION:When the welded part W of a stainless pipe S used as the cooling pipe of an internally cooling type cable is detected, a moving apparatus 2 having a search coil 1 attached to the leading end thereof is sent into the stainless pipe S from the end part of said pipe S. This moving apparatus 2 is supported in midair by a plurality of rollers 3 contacted with the inner surface of the stainless pipe S with elasticity and pushed into the stainless pipe S from the end part thereof, for example, by a pusher 4 such as a piano wire and the moving distance from the end part of the stainless pipe S to the center of the search coil 1 is measured by the push-in length of a pusher 4. The output of the search coil 1 generated by the welded part W is taken out by a lead wire 5 and detected by a high sensitivity voltage recorder 6. |
