Plug Mill Process is a proven process for manufacturing of higher diameter Seamless Pipes by heating round billets up to the plastic stage of steel and piercing in a Cross Roll Piercer. Further elongation is achieved through a Plug Mill in which the thick wall hot hollow is rolled through a pair of Top and Bottom Rolls with a plug inside to control the ID and achieve better internal surface finish.


To achieve close tolerance on the Wall Thickness. As the OD and the ID are controlled by external and internal toolings during hot rolling in Plug Mill and Reeler, the pipe will have closer tolerance, to cater to the requirements of OCTG and other applications.

Seamless tubes in the diameter range from approx. 60 to 406 mm with wall thicknesses from approx. 3 to 40 mm are produced nowadays on plug mills. The usual wall thickness range lies between the limits of normal wall thickness to DIN 2448 up to four times normal wall thickness as a function of outside diameter

The blooms are heated in a rotary hearth furnace to a forming temperature of approx. 1280 °C. Following high-pressure waterjet descaling, the bloom is pierced in the cross roll piercing mill to produce a thin-walled hollow shell which is elongated to between 3 and 4.5 times its original length, corresponding to a deformation level of between 65 % and 75 %.