In the oil and gas industry a rotating control device (RCD) or rotating control head (also referred to as a rotating drilling device, rotating drilling head, rotating flow diverter, pressure control device and rotating annular) is used to form a seal against drill pipe and isolate the region of well bore below the RCD from whatever is above the RCD. On an offshore drilling rig the RCD may be located just below the rig floor, just above the subsea Blow Out Preventer stack (BOP), or anywhere in the riser. Typically, the RCD uses a passive or active sealing element which is mounted to a bearing assembly to form a seal on the drill pipe. The purpose of the bearing assembly is to allow the sealing element to rotate with the drill pipe as the drill pipe is rotated by the rig.
Like reference symbols in the various drawings indicate like elements.