Buoys – rafts – and aquatic devices – Buoy – For mooring a vessel
Patent
1995-09-08
1997-07-29
Basinger, Sherman
Buoys, rafts, and aquatic devices
Buoy
For mooring a vessel
114230, B63B 2202
Patent
active
056517084
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an arrangement for buoy loading of hydrocarbons at sea, comprising a buoy means which is anchored to the sea floor by means of mooring lines and is connected to at least one riser line and is arranged to be received in a seat in a vessel for rotation with respect to the vessel about a generally vertical axis, said riser line being in flow communication with a lower connector member which is arranged on the buoy means and fitting together with an upper connector member arranged in the vessel, a flow communication being arranged between the upper connector member and one side of a swivel means, the other side of which being connected to a pipe system in the vessel.
Such an arrangement is known, e.g., from Norwegian patent No. 167.906. When used in rough weather areas, e.g., in the North Sea, the vessel will be moving all the time in order to assume the most favourable direction for meeting waves, wind and current. These movements cause frequent movements in the swivel means, which therefore is worn relatively quickly and becomes a critical element as regards the regularity of the arrangement. This problem becomes even greater if one wishes to connect further riser lines or injection lines to the ship because, in that case, the swivel will need more channels and becomes correspondingly complicated.
SUMMARY OF THE INVENTION
One of the objects of the present invention is therefore to provide an arrangement of the introductory type where frequent relative turning movements between the vessel and the buoy means can be allowed without concurrently causing mutual turning between the inlet and outlet sides of the swivel means.
This is obtained according to the invention by an arrangement of the introductory type, which is characterized in that said one side of the swivel means is arranged on a turing body arranged in the vessel spaced above said seat, in that the flow communication between the upper connector member and the swivel means comprises a flexible conduit which is resiliently supported in the turning body, and in that means are arranged for turning the turning body in steps in order to keep the turning body and the buoy means within a predetermined mutual angular relationship when the vessel turns about the buoy means in order to assume the most favourable orientation for meeting waves, wind and current.
The flexible connecting conduit can tolerate a certain twisting due to mutual rotation between the buoy means and the turning body, and the elongation necessitated by this rotation is provided by means of the resilient support of the conduit.
In case there is a desire to run several riser or injection lines via the buoy means, it is suggested according to the invention that each line be attributed its own passage through said lower and upper connector members and its own flexible conduit.
In many cases it will be desirable to connect remotely controlled equipment on the sea floor to a control unit in the vessel by means of a control cable. For this purpose it is suggested according to the invention to let such a connection comprise a resiliently supported control cable which extends between a connector on the buoy means and the turning body.
According to an advantageous embodiment of the invention, the flexible conduit or conduits are provided with a swivel, preferably at their upper end. This facilitates a larger rotation angle between the buoy means and the turning body without the torsion becoming too large in the flexible conduit. Even when using a larger number of conduits, e.g., ten, this will make it possible to obtain a mutual rotation angle of 70.degree. or more before the turning body has to be moved.
In order to facilitate the resilient support of the flexible conduit in the turning body in a simple and reliable manner, it is suggested according to the invention to provide the conduit with a rigid pipe bend which is connected to a tensioning device. This tensioning device may comprise a hydropneumatic line tensioning means, e.g., o
REFERENCES:
patent: 4604961 (1986-08-01), Ortloff et al.
Basinger Sherman
Maritime Tentech AS
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