Abstract: The manufacturing process for 238 mm series medium-heavy wall tubes is explored.By analyzing the forming mechanism of wall thickness inhomogeneity on medium-heavy wall tubes during the slight stretch sizing(reducing)process,and considering the capacity of the exsisting equipment and the actual production practice,the relevant hot tools and process parameters for 238 mm series medium-heavy wall tubes are designed and developed.The analysis indicates that by properly designing the mandrel size,reducing the reduction ratio on each rough rolling stand,and decreasing the reduction amount and pass ovality of the sizing mill,the wall thickness inhomogeneity on medium-heavy wall tubes can be decreased.