Inflatable sealing element

Abstract: The invention relates to a vessel comprising a detachable buoy (3) which is connected to the vessel near keel level. The buoy or the vessel comprise on their contact surfaces an annular sealing element (6) comprising at least one inflatable tube (7,8,9). By placing the inflatable tube on the contact surfaces, the buoy and the vessel can be firmly connected, even when the contact surfaces are not completely flat. A water tight seal is formed by the inflatable tube such that the room in the top part of the buoy can be drained. Hereby a firm connection is achieved and a dry room becomes available for placing structures such as for instance a manifold system.

Description: The invention relates to a vessel comprising a detachable mooring structure which is connected to the vessel near keel level, the mooring structure and the vessel each having a contact surface, the mooring structure or the vessel comprising on its contact surface an annular sealing element comprising at least one inflatable tube. A tanker comprising a detachable mooring buoy is known from US-A-4,604,961. The known tanker comprises a turret that can be connected to a mooring buoy by means of a mooring recess in the moonpool of the vessel. The known system has as a disadvantage that for a reliable connection of the buoy to the mooring recess, the contact surface must be accurately matched and be machined to a high degree of precision. Furthermore, no water tight seal is established, such that the space near the connecting interface of the vessel and the buoy will be below water level. From FR-A-2 348 848 a mooring structure according to the preamble of claim 1 is known in which a vessel is coupled to a subsea oil storage reservoir via a mooring column. The mooring column projects through an aperture in the hull of the vessel, around the circumferential wall of which an inflatable seal is placed to provide a closure for oil that is supplied through the mooring column into the hull of the vessel. The known mooring connection is not suitable for coupling a detachable mooring buoy to a vessel, in which contacts surfaces are placed in a generally parallel oppossing configuration. Furthermore, upon insertion of the mooring column into the recess of the vessel, the flexible seal may be damaged. It is an object of the present invention to provide a vessel, wherein the tolerances for the contact surfaces can be relatively large while still obtaining a proper fit. It is a further object of the present invention to provide a vessel with a disconnectable buoy, which can be engaged with the vessel in a water tight manner, without damage to the seals upon connection. Thereto the vessel according to the invention is characterised in that the mooring structure comprises a buoy, wherein upon coupling of the buoy and the vessel, the contact surfaces are in a substantially parallel, opposing configuration, the sealing element being positioned between two spaced apart abutment members, the sealing element being in its deflated state located below a contact surface of the abutment members. By placing the inflatable tube on the contact surface of the buoy or the vessel, the buoy and the vessel can be firmly connected, even when the contact surfaces are not completely flat. The inflatable tube can form a water tight seal such that the room in the top part of the buoy can be drained. Hereby the buoy will be pressed into its connected position by the water pressure prevailing at the depth of the buoy. Also can the room above the buoy be used to house equipement such as for instance a manifold system, or other structures that are not to be submerged. Upon coupling, the flexible sealing element is protected by the abutment members, such that damage to the sealing element is prevented. The buoy can be any connection body with a certain amount of buoyancy. However, the buoy can also be ballastable and not have any substantial buoyancy. The buoy can be a mooring buoy which is connected to the see floor by means of anchor lines, or can be a riser support buoy connected to a subsea structure such as a well head. In one embodiment of a vessel according to the invention, at least two inflatable tubes are located side by side in a radial direction, for improved sealing. Each sealing element may comprise a cross-section having a T-shaped wall part. The transverse wall of the T-shaped part provides a flat sealing surface. Each inflatable tube may in a radial direction be located between two abutment members, in the form of an annular wall, for effective sealing, and for keeping the tubes properly positioned. Preferably the sealing element is located on the vessel, each tube being connected to a fluid conduit for inflating the tubes. The source for providing pressurised fluid, such as compressed air, to the tubes is placed in the vessel. The tubes are inflated up to a pressure between about 1 and 10 bar. The diameter of the seals will generally be larger than 2 m. An embodiment of a vessel according to the invention will be explained with reference to the accompanying drawing. In the drawings: Figure 1 shows a cross sectional view of a vessel comprising a detachable buoy and a sealing element according to the present invention, Figure 2 shows an enlarged cross-sectional view of the sealing element of figure 1 and Figure 3 shows a detail of the inflatable sealing tubes of figure 2. Figure 1 shows a vessel 1 having a turret 2. To the bottom of the turret, a riser support buoy 3 is connected via a detachable connecting device 4. The buoy 3 can be drawn against thet bottom of the turret 2 by means of a cable 5 connected to a winch on the vessel 1. An inflatable sealing element 6,6' is placed on the contact surface of the vessel 1. As can be seen in figures 2 and 3, the sealing element comprises three inflatable tubes 7,8,9 . The tubes are circular and have a diameter that may for instance be larger than 2 m. The tubes 7,8,9 have a cross-section comprising a T-shaped part 10 with a flat wall part 11. The tubes 7,8,9 are each located between respective annular walls 12,13,14,15. Each tube is connected to a fluid conduit 16,17,18 which are attached to a fluid source on the vessel. After connecting the buoy 3 to the turret 2, the room 21 inboard from the sealing element 6,6' can be drained such that the buoy attaches firmly to the vessel and the connectors in the room 21 are not submerged.

Claims: Vessel (1) comprising a detachable mooring structure (3) which is connected to the vessel near keel level, the mooring structure and the vessel each having a contact surface, the mooring structure or the vessel comprising on its contact surface an annular sealing element comprising at least one inflatable tube (7,8,9), characterised in that , the mooring structure comprises a buoy, wherein upon coupling of the buoy and the vessel, the contact surfaces are in a substantially parallel, opposing configuration, the sealing element being positioned between two spaced apart abutment members (12,13,14,15), the sealing element being in its deflated state located below a contact surface of the abutment members. Vessel (1) according to claim 1, wherein at least two inflatable tubes are located concentrically. Vessel (1) according to claims 1 or 2, wherein each sealing element comprises a cross-section having a T-shaped sealing wall. Vessel (1) according to any of the previous claims, characterised in that each abutment member comprises an annular wall. Vessel (1) according to any of the previous claims, the sealing element being located on the vessel, each tube (7,8,9) being connected to a fluid conduit (16,17, 18) for inflating the tubes. Vessel (1) according to any of the previous claims, the vessel comprising a chamber located above the buoy and a pump for substantially freeing the room of water after connecting the buoy to the vessel.

Inventors: BRAUD JEAN, PERRATONE RENE, BRAUD, JEAN, PERRATONE, RENE, Perratone, René
Applicants: SINGLE BUOY MOORINGS, SINGLE BUOY MOORINGS INC.
Application year: 1996
Main classification: B63B22
IPC codes: B63B21, B63B27, B63B22