2-D vector field visualization of corrosion in a small-bore piping system using bobbin-type integrated Hall and GMR sensors arrays

This study proposes a 2-D bobbin-type magnetic field vector camera in nondestructive testing for inspection of corrosions in inner and outer diameter (ID and OD) of a small-bore piping system. 16.1 mm diameter bobbin probe was produced by integrated of 71 Hall sensors (BIHaS) and 71 Giant magnetoresistance sensors (BIGiS) in two circumferential lines at interval of 0.6 mm. The BIHaS and BIGiS could measure radial and axial components of alternating magnetic field. Thus ID and OD corrosions could be imaged in a 2-D magnetic field vector. Two small-bore copper (16.56 mm inner diameter, 1.27 mm thickness) and titanium (17.28 mm inner diameter, 0.86 mm thickness) pipes with ID and OD corrosions were inspected and presented in this paper. The measured signal of each sensor array was displayed in a single contour plot and combined 2-D vector plot in real-time during scan.