In a market economy, increasing the competitiveness of steel products is an urgent trend in science and practice. Development of production of new pipe steels in terms of pipe-rolling plant open joint-stock company «BSW – management company of holding «Belarusian metallurgical company» casted on continuous casting machine, was complicated by the emergence of low-alloy pipe steel grades of internal defects, which negatively affects the quality of the pipes. Visual evaluation of samples on the inner surface revealed rolled defects significant clusters, close to each other, having a longitudinal orientation. The edges of the defects are tortuous, torn. Defects found on the inner surface of the pipes are characterized as steel melting captivity and swelling. The reason for the formation of internal defects of hot rolled pipes «steel-melting captivity and swelling» was the rolling of defects in the macrostructure of the central zone (central porosity and axial liquation) of a continuously cast workpiece with a diameter of 200 mm.