IIW History 1948-1958

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At first sight, t he reading of a radiographic film would appear to be simple work which can be carried out objectively. Discussions between trained radio– graphers from the different member countries of the IIvV have, however, shmYn that this is not always the case. An early t a'>k of Commission \ was to improve the « reading » of radio– graphs as regards objectivit y, faithfulness and precision ; this ,,,ork was made possible by the adoption of a nomenclature for defect s of homogeneity, by a syst emati c classification of their images and by the adoption of IIW symbols characterizing the nature and scale of the defect s revealed, by making recom– mendati ons regarding satisfactory photographic conditions for exposure, etc. b) The Commission then p repared and gradually completed at its meetings a Collechon of R eference Radiographs of Welds (r ). This Collection was published under the auspices of the IIW \vith the assistance of four national institutions from member countries of the Institute. (1st edition 1953 ; supplements 1953 and 1954). The purpose of the Collection is t wofold : r) to provide operators and radiographers who have to read films with standards of comparison for the prin– cipal defects as normally met with in practice; 2) to facilitate the training of welders and radiographers. The Collection is in t wo forms : r) a card index, the films having perforated mounts which allow radiographs of a given t ype t o be immediately withdrawn; 2) an album of positive images. The Collection a lso contains a scale of photographic densities. This publication has met with considerable success and is increasingly used in the industri al world. c) Another result of the work of Commission V has been t o reveal the con– fusion which used to exist with regard to the proper use of instruments formerly called « penetrameters », which were used sometimes to appraise the quality of a radiographic i1n::1ge, sometimes to evaluate the volume of a defect in a weld. The Commission began by banishing the word « penetramet er » for the first and principal of these uses and has replaced it by t he expression : I mage Q,1,tafrty Ind1:cator, which is abb reviat ed t o I QI both in F rench a nd English, the two official languages of the Institute. The only purpose of an IQI is t o provide the reader of a radiograph with a guarantee that it has been t aken in conditions such that the ima<>e should be irreproachable. Going a stage further, the Commission compared the principal I Qi s used and concluded (2) by recommending the use, for all purposes, of one of the t\Yo types of I QI mentioned below : l ) IQI step indicator with steps in the geometrical ratio of r.25 and holes of a diameter equal to the thickness of the st eps; 2) IQI wire indicator with diamet ers in a geometrical ratio of r.25. For countries usi ng the British system of measures, these IQis must be constructed in inches and fractions of inches. The study of the possibilities of estimati ng the volume of cert ain weld defects by a « penetrameter » has been begun, but no conclusions have yet been reached. At present, it seems that this application is only possible for particular t ypes of mat erial and defects. Special skill and judgement are necessary for thi s appli– cation.

( r) See Chap. II, sect. 3. (i) ) Iadrid Assembly 1956.