The History of ACT

Abstract

Automated Ultrasonic Testing (AUT) of welds has a long history. Around 1950, the first ideas on how to inspect a weld with multiple ultrasonic transducers and a scanning mechanism arose and were patented. The first AUT machine for the inspection of pipeline girth welds was successfully tested in the lab in 1959. In this paper, the history and backgrounds of mechanised and automated ultrasonic inspection are illustrated with pipeline girth weld inspection as an example. The paper not only addresses the technical developments, but also standardization of the basic zonal concept, development of acceptance criteria for weld imperfections and improvements in accurate defect sizing which were crucial for AUT introduction and acceptance. The paper will highlight lessons learned during this process. Recent developments in phased array technology, using for example innovative Inverse Wave field EXtrapolation (RTD IWEX) technology are going to enable 3D imaging of defects in the real sense. First results show not only enhanced defect detection capabilities but also reliable determination of shape, orientation and size with the ultrasonic wavelength as the only limitation. The potential impact of such a development will be discussed.