Development of Electromagnetic Cylinder-Type Probe for Inspection of Heat Exchanger Tubes

This article presents a cylinder-type magnetic camera (CMC) system in nondestructive testing (NDT) of a heat exchanger (HX) tube. The CMC system is developed for the inspection of corrosion on HX tubes of nuclear power plants. The CMC probe works based on the principle of eddy current testing, in which a single-large bobbin coil is used to supply eddy current on the tube, and a matrix array of InSb Hall sensor is used to measure the electromagnetic field around the corrosion. The CMC system can measure both the real and imaginary components of the magnetic field. The CMC system can operate in two modes: single-line scan mode by selecting a single-line Hall sensor or area scan mode by the electrical scan. The limitations and advantages of each operation mode will be presented. The CMC system has the potential for further applications such as evaluating corrosion size, shape, and locations.