環形配列 磁氣센서를 利用한 高壓給水加熱器 傳熱管의 非破壞檢査

Abstract

A non-destructive testing system is developed for the inspection of austenitic stainless steel heat exchanger tubes. First, integrated Hall sensor arrays are disposed under absolute type coil. When an alternating current is applied to the bobbin coils, an induced current in circumferential direction is generated in the heat exchanger tube. In this structure, an eddy current is generated around the defect, and the impedance of bobbin coil changes. Therefore, it is possible to estimate the presence and location of a defect by analyzing the bobbin coil signal, i.e., the amplitude and phase shift. Furthermore, the eddt currents generated around the defects distort the time-varying magnetic field distribution, so the shape of defect can be evaluated by the measurement of these distortions using the bobbin-type integrated Hall sensor array and the AC amplification signal processing circuit. The developed system is verified using the artificial defects introduced into the SS304 heat exchanger tubes of the high-pressure water feeder.