A High-Pressure Swivel for Natural Gas Service and Oscillating Motion in a Marine Environment

A joint development program has produced a unique flowline swivel for high-pressure natural gas service under continuous, small degree rotation, oscillating service. The swivel uses an elastomeric bearing element made up of alternate, frusto-conical shaped rings of metal and rubber (elastomer) to absorb continuous small degree rotary oscillations or flexures of the swivel. It accommodates larger oscillations, including complete 360-deg rotations, by locking the elastomeric element at its maximum design flexure capability and permitting the entire shaft assembly to rotate relative to the housing. A 6-in. (152.4-mm), 6000-psig (41,370-kPa) prototype successfully passed a rigorous qualification test program. The swivel should be useful in offshore marine production riser systems and loading terminals.