A simple pipe turning manually operated set of rolls would need the following :

1. Two pairs of hardened and tempered C-45 machined rollers. Diameter can be selected based on the pipe dia.

2.One pair of base plate of at least 16 mm thick ( 200 x 1000 )

3. Two pairs of support plates with grooves at equal distances from the centre line so that the distance between the rolls could be varied based on the pipe diameter. The vertical support plates should be identical to each other. The shape of the support plates and the distances of the grooves from the centre line is critical.

4. Two pairs of mandrels or shafts to mount the rollers on the support plate grooves. The shaft O/D is to be machined to match with the I/D of the rollers.

5. A few stiffeners between the support plates to provide rigidity.

This is the most elimentary design for a set of turning rolls. You can improvise on it by making it motorised, mounting the rolls on bearings etc.