Self-propelled x-ray flaw detector

摘要

A self-propelled X-ray flaw detector for radiographic inspection of welded joints in pipelines comprises a carriage 1 mounting a motor 2, a detector 3 having two Geiger counters 4 and 5, a pulsed X-ray generator 6, and an exposure and carriage electronic control system 7. A memory unit 8 in the control system 7 has four storage elements containing information about the motion of the carriage. As the carriage moves in direction A, first one and then the other of the Geiger counters receives radiation from an isotope source positioned near a joint, and by means of logic circuitry in the control system 7, the information in the storage elements is modified to stop the carriage and to operate a timer 16 to expose the weld. During exposure the X-rays may interfere with the information in the storage elements, but by means of a square-wave generator 12 and the logic circuitry, the stored information is correctly reset in order to eliminate false operation of the memory unit 8. IMAGE