A rotary machine for clamping, rotating and tilting pipes with round profiles in manual or automatic welding, mainly in the field of pipe construction (prefabrication and assembly on site) as well as in the manufacture of plant. Apart from being extremely economical (single handed operation, no interruptions due to repeated turning of the pipe to be welded), this machine also offers improvements in quality – there are no interruptions in the joint and a conti- nually precise horizontal position of the pipe is maintained.