IIW History 1948-1958

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3° Ultrasonic Inspection . On the foundation of the IIW in 1948, experimental demonstrations on the practical possibility of detecting certain defects in welded assemblies were publicly presented by a member of the Belgian Institute of \Velding with the help of apparatus developed in Belgi um. This was the point of departure of research and investigations undertaken in different countries cooperatively with a view to improving and extending the inspection of welds by ultrasonics. After an investigation on exist ing t ypes of apparatus (1) and a statement of the qualities sought by inspect ors, which had the effect of stimulating makers t o try, after 1953, to meet the wishes of the IH\ , the Commission undertook a n investigation a nd research work on the most adequate methods in each field of welding (2). Among the results which have already been achieved may be mentioned the following : a) surface defects, such as defects in rolling in the base metal of a welded assem– bly, a re easily detectable (3); b) cracks and lack of fusion in weld seams, are easier to detect, a t least in certain cases and when account is t aken of the state of the surface, than by radio– graphy ; c) the inspection of spot welds is simple, but little is known about the relation– s hip between their appearance and their mechanical behaviour (4); d) ultrasonic inspection of undressed weld seams is possible, but special expertise is necessary 'vhen a \veld has to be judged by this method onl y; the use of radiography and ultrasonics combined is often the satisfactory solution (5); f) it is possible, using simple ultrasonic methods of inspection, to arrive at a qualitative evaluation of penetration in the case of fillet welds in Tee joints in steel. Quantitative measurement may also be achieved (7); g) in 1957, the IIW recommended a steel reference block by which an ultrasonic inspection apparatus may be characterised and which allows compa ri son of the calibration of a n apparatus from one moment to the next (8); h) finally, it is worth mentioning the Commission 's view that operators carrying out inspection by ultrasonics must be carefully trai ned . The use of ultrasonic inspection and research work on new scanning tech– niques are developing rapidly. Such rapid development has its risks ; if the scanni ng of a weld is apparently simple and if the apparatus is easier to handl e and less expensive than radio– graphic apparatus, it nevertheless remains true that the interpretation of the results is more difficult because the control is less direct. Consequently, Com– mission V is carrying out a long term programme of work which is sufficiently systematic in character t o enable it ultimately to provide fabricators and welders " ·ith real guarantees in the use of ultrasonic inspection. e) in certain special cases, such as that of induction welded steel tubes, ultra– sonic inspection can be adapted for continuous automatic inspection (6) ;

(1) (Paris Assembly r950.) (2) (Paris Assembly 1950 and Oxford Assembly 1951.) (3) (Brussels 1948, Paris 1950.) (4) (Oxford 195 r.) (5) (Oxford 1951 , Gi:iteborg 1952.) (6) (Document V-4-54 and annua l R eport F lorence 1954.) (7) (Document \"-17-55, Zurich 1955 .) (8) (Essen Assembly 1957.)