| 摘要 |
PURPOSE:To efficiently measure internal and external flaw without preliminarily magnetizing the interior of a metal pipe, by moving the coil wound around a magnetic bobbin through a ferromagnetic metal pipe while a low frequency AC current is flowed to said coil to perform eddy current flaw detection. CONSTITUTION:Coils 4, 6 are wound around a ferromagnetic bobbin 2 to constitute a probe 8 and the bridge 10 of the eddy current flaw detector main body 22 connected to a recorder 20 is connected to said probe 8. A low frequency AC exciting current is applied to said bridge 10 from an oscillator 12 and the probe 8 is inserted in a ferromagnetic metal pipe 24 while a low frequency current is flowed to the coils 4, 6 to be moved through said metal pipe 24. By the movement of the probe 8 in the metal pipe 24, the interior and exterior of the metal pipe 24 are subjected to eddy current flaw detection and the internal and external flaws of the metal pipe 24 are displayed on a cathode ray tube 18 without preliminarily magnetizing the interior of the metal pipe 24 and recorded on a recorder 21.
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