In this investigation, rapidly quenched ribbons prepared by a melt spinning technique have been used as a magnetostrictive sensor (MsS) element for the generation and detection of guided waves traversing through a pipe. The materials we have used in the present study are the rapidly quenched Fe 80Si 8B 12 and Fe 40Ni 40B 20 which have a high magnetostriction constant. The experiments were conducted on a bare Al tube after generating proper dispersion curves. The experiments were carried out using as-spun and annealed ribbons. After optimizing the AC magnetizing field, DC bias field and frequency (from software), longitudinal guided waves were generated in the tubes using MsS ribbons. Measurements were carried out to test the sensitivity of this sensor to both circumferential discontinuity (saw cut) and defect free bare aluminum tubes at a frequency of 76kHz. The effect of defect size on the sensor signal was also investigated. Using the present technique, the defects were not only identified but their location in the pipe was also estimated. © 2012 IOP Publishing Ltd.