The purpose of this work is to develop high-strength mechanical designs for feeding oxygen into the cavity of converters. On the basis of the conducted set of industrial experiments, for the first time the hypothesis of significant increase of lance tip durability at providing cooling of nozzle zones of their copper bowls was confirmed and high degree of efficiency of this method was established. A new design (patent-protected) of lance tip with five extended Laval nozzles was developed, which due to a more rational distribution of a coolant in it, allowed increasing its resistance by 2.205 and 4.195 times in comparison with two similar designs. It was found that the external welding seams around the Laval nozzles at the end of the copper bowl are the limiting link that prevents significant durability of welded lance tip structures. This is in favor of forged and/or solid-steel lance tip designs with higher durability, which would be improved to a greater extent by providing cooling in the back-to-back (with water flow) zones of the copper bowls. The results of experimental evaluation of effectiveness degree of lance tip design, reflected in the work, testify to the possibility of more effective solution of the problem of low durability of lance tip of this type, which is always present at the converter shops in operation.