TWI provides industry with engineering solutions in welding, joining and associated technologies through information; advice and technology transfer; consultancy and project support; contract R&D; training and qualification; and personal membership. It is the only single source of expertise in every aspect of joining technology for engineering materials; metals, plastics, ceramics and composites. TWI carries out confidential research contracts for industrial members. An extensive programme of core research and collaborative projects is also conducted. TWI serves companies in almost every industry sector - from motor sport teams to offshore oil platform operations; from microchip suppliers to civil engineers; from supermarkets to legal bodies. TWI is a non-profit distributing, membership-based company. It is owned by its Members - 3,500 from 60 countries around the world. The majority of the world's leading automotive OEMs are member companies. TWI's mission is to deliver world-class services in joining materials, engineering and allied technologies to meet the needs of a global membership and its associated community. Its vision is to be the most influential global network for stimulation and development of economic value and quality of life through Materials Joining Technologies. TWI's three decades of in-depth experience in all areas of ultrasonic inspection has made it an acknowledged world-leader. It has done preliminary work on NDT of spot welds in which weld quality was compared with ultrasonic response. It has also worked on the spot welding technique itself almost since its foundation in the mid 1940s. Recently this work has concentrated on spot welding of high strength steels. Thus it spans both the making of the welds and their inspection.