| 摘要 |
PURPOSE:To efficiently and easily perform a flaw detection test with high accuracy, by magnetizing a steel pipe by directly supplying a current thereto from an external power source and scanning the flaw detection testing coil inserted into the steel pipe to perform flaw detection. CONSTITUTION:Electrode terminals 5 are contacted with a steel pipe 1 and a current is supplied to the steel pipe 1 from an external power source 3 to magnetize the same to obtain a magnetic saturation state. A current is blocked according to necessity to bring about a residual magnetization state. A flaw detection testing coil 2 is inserted into the steel pipe 1 held under the magnetic saturation or residual magnetization sate and scanned to perform a flaw detection test. When the steel pipe 1 has a crack or other flaws, change is generated in the eddy current flowed to the coil 2 and the impedance or induced voltage of the coil 2 changes to obtain an electric signal. This signal is guided to a flaw detector 6 and the presence or degree of a flaw part is judged from the amplitude and phase of the signal. By this method, the flaw detection test is efficiently and easily performed with high accuracy. |
