EMA angle-probe prototype tests steel tubes on-line

A newly developed prototype system for the ultrasonic inspection seamless ferritic steel tubes using electromagnetic-ultrasonic transduction is described. The operation principle is that of an ultrasonic phased array. The system uses vertically polarized angle-beam shear waves and surface waves and can electronically be switched from one of these modes of operation to the other. A typical radiation pattern for the angle-beam mode is illustrated. The sensitivity of the system satisfies the German SEP 1915 and SEP 1918 standards. Detection of the corresponding calibration defects is achieved at a circumferential speed of 2 m/s with a signal-to-noise ratio of 20 dB. This sensitivity has been confirmed in a field test under in-line conditions. (IZFP