Abstract: The extrusion roll assembly is a critical part of the hi-frequency welded pipe mill.Nowadays,hi-frequency welded pipes with O.D.above 114mm are produced by means of the conventional multi-roll extrusion assembly which has such disadvantages as rather complicated frame,inconvenient adjustment and inconsistent quality of pipe weld seam.It has been proven that the subjective extrusion roll assembly with a unique two-high/multi-level structure newly developed by the author's own company is very effective in operation.