Tofd inspection of v-groove butt welds on the hull of a container ship with a magnetically adhering wall climbing robot

Abstract

This paper presents the results of Time Of Flight Diffraction (TOFD) ultrasonic inspection of long welds on the hull of a container cargo ship. The TOFD probes are deployed by a low\ncost miniature climbing robot that adheres to the steel hull by using rare earth permanent magnets. 100% detection of defects sized larger than 0.6mm is obtained in V groove butt\nwelds by a single pass scan. A scan and B scan results obtained by the inspection robot detect weld defects such as porosity, lack of root penetration and internal cracks.