The turbulent heat transfer and the friction in a circular pipe with ring ribs detached from the pipe wall have been studied experimentally. The effects of detached distance-to-rib height ratio, rib thickness-to-rib height ratio, and flow Reynolds number are examined for fixed rib height-to-pipe diameter ratio and rib pitch-to-rib height ratio. The clearance ratio (C/h) is varied from 0.222 up to unity and the Reynolds number ranged from 2.0