2003 Volume 21 Issue 7 Pages 770-775
Recently new ultrasonic flaw detection system called TOFD method is utilized to externally inspect the inner and outer surfaces of weld seams on spherical storage tanks while tanks are in use. In this system, the robot mounted the sensors is not only permitted to travel along the weld seam rapidly but also required to follow the weld seam precisely. In this paper, the development of a magnetic-wheeled robot that can follow the weld seam within 5 mm based on feedback control is described. Since October 1999, this robot has been in experimental operation on an actual spherical tank. Practical introduction of this robot will shorten inspection time by about one week from the conventional 23 days, and will reduce the conventional number of inspectors required from 4 to 2-3.
