Inspection robot for spherical storage tanks

Abstract

Osaka Gas Co. Ltd has utilized ultrasonic flaw detection systems (time of flight diffraction method) to externally inspect the inner and outer surfaces of weld seams on spherical storage tanks while the tanks are in use. In these systems, the vehicle mounted with an ultrasonic flaw detection probe is designed to travel in a straight line only. To improve the work efficiency, we developed an inspection robot that is propelled by four independently driven magnetic wheels. This robot has been in experimental operation on an actual spherical tank. The introduction of this robot has shorten inspection time by about one week from the conventional 23 days, and reduced the conventional number of inspectors required from 4 to 2.