Thanks to the careful organization of this conference, the unambiguous definition of its scope, prior circulation of papers, and the example to be followed as outlined by Kelly in his account of the work of Dr Rosenhain, it is possible at this stage to save precious discussion time by addressing the topic of engineering requirements for structural steels almost without preamble. The three papers in this session, on bridges by Harper, line pipe by Mercer, and offshore structures by Cotton, are completely complementary. Thus Harper, although obviously aware of the necessary inhibitions of the bridge designer, arising simply from the need to ensure safe erection, and long operating lives despite the rigours of wear and weather, and the maintenance of public confidence, shows such an open mind that he would consider the use of adhesive joints in future constructions. In so doing he implies the invitation to consider other far reaching ideas that could be introduced. Mercer’s paper is packed with information, in terms of numbers that stretch the imagination. Yet the sources are authoritative, and a fair impression is given of the challenge of pipeline construction to be expected through the next decade. Cotton gives a balanced comparison of the relative merits of concrete and steel offshore structures, not without confirmation that the former embody more steel than the latter. In addition, he mounts a vigorous challenge with regard to existing methods of quantifying notch toughness requirements, ranging from material selection, through fabrication procedures to quality control. He is quite specific in describing particular problems of other types of service failure, in need of the attention of the physical metallurgist
