Feasibility of under-lagging corrosion detection in steel pipe using the magnetostrictive sensor technique

The feasibility of inspecting under-lagging steel pipes without lagging removal using the magnetostrictive sensor (MsS) technique is described. With the MsS technique, elastic waves are launched along the length of a pipe, and reflected echoes from defects such as cracks or corroded areas are detected using noncontacting sensors. Experimental results obtained from 6-m long, 3.8-cm diameter steel pipe samples before and after inducing simulated defects in the pipewall are presented, and the potential capabilities of the MsS technique are discussed.