A tube or other structural member particularly for use in aircraft is made from one or a number of lengths of sheet metal rolled, drawn or pressed to shape and having outwardly flanged edges, adjacent flanges being connected together by electric resistance welding and some or all of the joints so formed being subsequently pressed inwards so that they are accommodated within the contour of the member. In one form, a streamlined strut may be formed by welding the flanges of two shaped strips of metal 8, 9 together and then bending the flanges over and pressing them down into the contour as in Fig. 2 or pressing them edgewise into the strut. In the latter case the depth of the flange may be decreased in the process. In a further modification a boom is formed from five strips of metal, the seams 18 (Fig. 4) being pressed in and the flanges 17 being employed to join the booms to the web. The various members may be formed of annealed metal, which is subsequently hardened by heat treatment. According to the Provisional Specification, a tube made in the manner set out may be heat treated by the electric resistance process described in Specifications 207,279 and 240,902 [both in Class 83 (iv), Metals, Working].
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