HEAVY-WALL PIPE PRODUCTION WITH THREE-HIGH CROSS-ROLLING REDUCING PROCESS

The existing problems regarding production of hot-rolled heavy-wall seamless steel pipes withsmall tube-rolling mill are analysed,and also described is the non-mandrel cross-rolling reducingprocess for small-sized heavy-wall seamless steel pipes with a φ108mm three-roll tube mill.The pro-cess makes it possible to eliminate undesirable internal-square profile of the pipe,reduce croppingamount and metal loss,being suitable for pierced-shell (or elongated-shell)non-mandrel reducing andtube non-mandrel sizing.