Abstract: Briefed in thearticleare themanufacturing processesfor hot-rolled seamlesssteel tubes,and the shapes and types of mandrels as used thereto.Also analyzed here are the operation manners and characteristics of different pipe-rolling mill mandrels,and the influences thereby on such aspects as the product size range and rolling cycle of the mill,the deformation degree of the rolled-piece and the tube wall thickness accuracy,etc.Moreover the material of and the formation method for the mandrel are also described.It is regarded via the analysis that the mandrels are sorted into three types as long,medium-long and short ones according to their length,and categorized as four types as fixed, floating, retained and semi-floating ones according to their movement status.Most of the long and medium-long mandrels are solid ones.Nevertheless,for the Assel mill and some mandrel mills,hollow mandrels are used for the need of retained-mandrel operation.In fact,most overwhelming majority of the long and medium-long mandrels are cylindrically-shaped,while coned mandrels are used for rolling light-wall pipes by few,very few retained-mandrel pipe mills.