A new method for converting round pipes into octagonal ones with a ratio of width and height 1/3.018 along the median line of the design section is presented, which maximizes their bearing capacity of bending strength. Its originality has been confirmed by patent examination. The calculation of the optimal parameters of thin-walled octagonal sections is given according to an approximate method tested using profiles from a standard assortment. The entire diagram of changes in the design parameters of octagonal pipes during the transformation of their cross sections from vertical to horizontal configurations is shown, including the transition through a modification with equal dimensions of width and height, the outlines of which have the shape of an equilateral (regular) octagon. The demand for octagonal profile pipes is revealed not only in metal, but also in pipe-concrete structures. A comparative analysis of the design parameters of optimized sections of profile pipes, repurposed from round to oval, flat-oval, semi-flat, rectangular, octagonal, has been performed. Optimized tubular profiles with increased bending strength can be attributed to beam modifications.