IIW History 1948-1958

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this preliminary report and to make their comments known so that it will shortly be possible to publish a useful guide on the choice of materials. This study of steels has shown that no equivalent materials exist in the different standards but that it is always possible to find a substitute material which is close to the original. The relationship with ISO/TC rr has been established on an excellent basis The Chairman of Commission X I attends its meetings as IIW observer and the late Mr. GILG (U.S.A.) was a member of Commission XI of the IIW. In addition, many delegates participate in the work of the t wo bodies. Mr. GILG had under– taken t o draw the attention of the members of the ISO Committee to the collec– tion of recommended welded connex ions and to the new report on allowable stresses. Good relations a re also maintained through the intermediary of certain members with the European Committee for Boilermaking and Kindred Steel Structures. The details of assemblies prepared by Sub-Commission A have been approved by this Committee as a satisfactory basis on which design offices can work. The report published on allowable stresses and entitled Pressure Vessel Design only deals with carbon steels used at up to 350° C and low alloy steels used at up t o 410° C. The behaviour of steel at higher t emperatures, where the creep properties become p redominant, is still being investigated by Sub-Com– mission B. The first report on creep has already been drafted and comment s on it have been invited. In addition, the Commission has asked Sub-Commission B t o continue the investigation of stresses in clrum heads and, in particular, of the influence of non-linea rity of the stress distribution over the plate thickness in cases whe re the ratio wall thickness over radius of curvature is high. It was said above that the Commission considers that strain hardening, which probably plays an important part in the problem of local corrosion, should be avoided. In this connexion, it is necessary t o know the y ield point of the material. The method of det ermining this value varies from one country to another. It can happen , for example, that t he point determined by the British is different from that determined by the Germans for the same steel. It was therefore decided to carry out research work with regard t o the these differences. The list of st andardized st eels for boilers and pressure vessels is to be checked and completed by the national organisations. It was decided at the last assembly, held at Essen, that t wo ·working groups would be set up , both t o be responsible for drafting special report s t o be submitted t o the Commission at the 1958 assembly. The first v·vorking group will report on non-destructive t esting. Since a value of loo% has been agreed for the weld efficiency factor, the Commission considered that non-destructive inspection should always be carried out. It may happen, however, that in certain cases non-destructive inspection on a specimen can be considered sufficient. In addition, Commission V (Testing, Measure– ment and Control of Welds) must be asked many questions about, fo r example, the maximum plate thickness up to which radiography works effeciently, the t ype of image quality indicat or to be used, etc. A proposal is also to be drafted, on the basis of the Collection of Reference Radiographs published by the IIW, with a view t o establishing ·which defects do not render a weld inaccept able. 4. WORK IN HAND AND FUTURE PROGRAMME.