Oceans of knowledge
Internal Turret Mooring systems
The internal turret mooring system includes a turret system that is integrated into the hull structure at the bow of the vessel. The internal turret is a slender structure that is connected to the vessel structure via a large-diameter 3-race roller main bearing at the top and via a large-diameter sliding bearing at the bottom.
The slender turret shaft ensures that the horizontal loads from the risers and mooring lines are transferred via the sliding bearing to the vessel, while the remaining forces from the turret and the vertical loads from the risers and mooring lines are transferred via the 3-race roller bearing. The supports of the bearings are integrated into the turret casing, which is part of the modified vessel hull structure. Typically the turret casing is a cylindrical structure that is integrated between the bottom and the deck of the vessel and transfers the turret loads via the vessel web frames to the vessel hull structures.
The turntable decks are positioned on top of the 3-race roller bearing. The turntables include the process facilities for commingling fluids from the risers using manifolds, as well as pigging facilities and/or chemical injection facilities to assure the flow in the risers. In addition, the turntables provide space for subsea control facilities, to enable safe operation of the subsea manifolds and well heads. The highest deck level of the turntables provides space for the swivel stack, which transfers fluid and electrical power to the turret access structure that is located on the vessel main deck. This access structure also provides support access to the different turntable decks.