Abstract: Several problems are encountered with the Assel pipe mill featuring full-floating rolling and out-let table-located drive system, including swing-caused mandrel-bending, poor guidance to the shell/mandrel and serious temperature rise of the main gear reducer.Accordingly, a series of modifications are carried out, i.e., modification of mandrel-cooling system by means of hot-rotating straightening and stepped-cooling process;changing the drive type of the main gear reducer into individual drive, and improving the shell-guiding device with a better structure to increase the opening/closing range.Thanks to these measures, the temperature inhomogeneity and additional bending of the mandrel being cooled are mitigated, and the outlet table guidance to the shell is much better than before, resulting in good effectiveness.