| 摘要 |
PURPOSE:To calibrate sensitivity with a small artificial error by providing a detector for the oscillation distance of a probe holder, an arithmetic circuit for the tube circumferential angle (circumferential distance) when the echo from a probe is maximum, and a display device or recorder. CONSTITUTION:The external diameter D and thickness T of steel pipe of a next lot are inputted from an external controller 25 to a flaw detector 18 and a switch 23 is connected to a contact A with a signal C. The pipe circumferential angle arithmetic circuit 21 calculates a preset value thetap matching with respective contactors 3-8 and it is displayed 24. Contactor positions are set temporarily according to the display value. The contactor holder is brought into contact with a steel pipe and swung by a proper angle in the pipe circumferential direction to adjust the sensitivity between respective channels to the same level. At this time, a holding circuit 22 is supplied with a dynamic pipe peripheral angle thetad and the current pipe circumferential angle is held with the maximum echo generation period signal tm from a generator 20. When the calibration sequence operation of a mechanism side is completed, the switch 23 is connected to a contact B with the signal C of the controller 25 and the corrected value thetax of the pipe circumferential angle where the maximum echo is generated is displayed 24. The respective contactor positions are corrected according to the display value and the sensitivity calibration is completed.
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