Abstract
This article discusses the results of researches of continuously cast pipe billets structure used in the production of oil and gas pipes. In the course of the work, it has been proposed to replace the solid cast billet with a hollow one, which helps to improve the structure and eliminate defects that form in the center of the billet. The researches have demonstrated that the hollow billet has a number of advantages over the solid one. In particular, improved quality of the macrostructure due to the absence of misoriented crystals zone, a more uniform distribution of non-metallic inclusions and liquating elements, as well as a more dispersed microstructure have been noted. This research is of significant practical importance for seamless pipe manufacturers, since the proposed solutions will improve the quality of the billet and reduce the level of defects.