GB2045200A

GB2045200A - A movable connecting conduit between a mooring buoy and a submerged pipeline

Info

Publication number: GB2045200A
Application number: GB8008759A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1979-03-16
Filing date: 1980-03-14
Publication date: 1980-10-29
Also published as: JPS55126181A; NO152599B; NO800738L; AU5645580A; GB2045200B; ZA801522B; AU532154B2; NL7902096A; CA1120375A; NO152599C

Abstract

A movable connecting conduit between a mooring buoy 1 for fluid transfer and a submerged pipeline 4, characterized in that, seen from the mooring buoy in the direction of the pipeline, the connecting conduit is built up of at least one hose 5 and at least one rigid pipe 6, which rigid pipe is movably connected to the pipeline 4, while at least one flexible tension member 17, 18, which is under tensile stress, extends between the mooring buoy 1 and the rigid pipe end 14 located near the hose. <IMAGE>

Description

SPECIFICATION A movable connecting conduit between a mooring buoy and a submerged pipeline The invention relates to a movable connecting conduit between a mooring buoy for fluid transfer and a submerged pipeline, the mooring buoy being provided with means for mooring thereto a ship which is to be loaded or unloaded. A mooring buoy of this type is described, for example, in British patent specification No. 977,451.

For this purpose movable connecting conduits are known which are entirely built up of hoses. When a high specific gravity fluid, for example a liquid/solid slurry, is passed through such a movable connecting conduit entirely built up of hoses, the connecting conduit will easily be able to sag. Owing to the sagging, stresses may occur which may give rise to crack formation and even rupture of the conduit.

Another drawback of a movable connecting conduit entirely made up of hoses is the relatively short lifetime of the hoses. Moreover, the hoses are subject to substantial wear owing to the continuous movements of the mooring buoy in relation to the submerged pipeline, as a result of which worn hoses must often be replaced. Owing to the high price of the hoses their replacement means an economic disadvantage. Moreover, owing to the rapid wear of the hoses the mooring buoy often cannot be used.

Another known movable connecting conduit between a mooring buoy and a submerged pipeline consists of a series of rigid pipes which are movably interconnected. Connecting conduits of this type are, for example, known from British patent specification No. 1374392 and Netherlands patent application No.

7412517.

A drawback of a connecting conduit of the lastmentioned type is that the rigid pipe(s) located closest to the mooring buoy can easily be damaged when a ship moored to the buoy bumps against the rigid pipe(s).

The risk of a rigid pipe being damaged by a ship will be greater according as larger ships provided with a bulbous bow are moored to the buoy.

The object of the invention is to remove the abovementioned drawbacks, which are inherent in the known movable connecting conduit, by providing a movable connecting conduit which is characterized in that, seen from the mooring buoy in the direction of the pipeline, the connecting conduit is built up of at least one hose and at least one rigid pipe, which rigid pipe is movably connected to the pipeline, while at least one flexible tension member, which is under tensile stress, extends between the mooring buoy and the rigid pipe end located near the hose.

With this proposed movable connecting conduit the chance that a ship will cause damage is small, since the hose part of the conduit has a high degree of flexibility and in the event of a collision it can therefore readily bend away without permanent deformation.

Owing to the presence of said flexible tension member it is prevented that the hose part is subjected to excessive tensile stress. In the event of a collision this flexible tension member can also readily bend away without incurring damage.

Moreover, the hose according to the invention is stretched as much as possible and under any conditions it is subject to only a slight degree of bending. This is an advantage compared with a connecting conduit entirely built up of hoses, in which case the hoses, for example in the event of strong currents or wave action or high specific gravities of the fluids to be transported through the hoses, are highly subject to bending and will therefore soon be worn out. As may appear from the foregoing, the lifetime of the hose part of the connecting conduit according to the invention is prolonged considerably, owing to which a more economic use can be made of the mooring buoy.

The invention will now be further discussed with reference to an embodiment of the invention, as shown in the drawings, wherein: Figure 1 is a side-view of a movable connecting conduit according to the invention, and Figure 2 is a front view of part of the movable connecting conduit seen in the direction II according to Figure 1.

Figure 1 shows the submerged part of a single buoy mooring or mooring buoy 1 for fluid transfer which is connected to the bottom 2 of a body of water 3 by means of anchor chains (not shown in the drawings). The mooring buoy 1 is further provided with conventional means (not shown in the drawings) for mooring a ship to the buoy. A fixed pipeline 4 for the supply and discharge of fluid is located near the bottom 2.

A movable connecting conduit is located between the mooring buoy 1 and the pipeline 4, which connecting conduit is formed by a hose 5 and a rigid pipe 6, which pipe is provided with reinforcing elements 7 and is connected to the pipeline 4 by means of a universal joint 8.

The universal joint 8 has a rotary shaft 9 normal to the plane of the drawing and a rotary shaft 10 located in the plane of the drawing. At the universal joint 9 the pipeline 4 and the rigid pipe 6 are interconnected by means of a hose piece 11, in order to create a flexible fluid connection between the pipeline 4 and the rigid pipe 6.

The hose 5 is built up of a number of hose parts 12 which are interconnected by means of flanged connections 13. The ends of the hose 5 are connected by means of flanged connections 14 and 15, respectively, to the rigid pipe 6 and a pipe 16 which forms part of the mooring buoy 1.

Furthermore, two flexible tensile members in the form of chains 17 and 18 which are subject to tensile stress, extend between the mooring buoy 1 and the rigid pipe 6, which chains are connected to the rigid pipe 6 and the mooring buoy 1 by means of universal joints 19 and 20 respectively. The universal joints 19 and 20 are provided with a rotary shaft 21 and 22 respectively, normal to the plane of the drawing, and a rotary shaft 23 and 24 respectively, located in the plane of the drawing. Between the universal joint 20 and the mooring buoy 1 there is a rotatable coupling 25 allowing rotation around a vertical axis.

The universal joints 8, 19 and 20, together with the rotatable coupling 25, allow displacements of the mooring buoy 1 in relation to the pipeline 4, so that the occurrence of torsional stresses in the hose 5 and the rigid pipe 6 is prevented.

In order to prevent the hose 5 being damaged by the chains 17 and 18, the hose 5 is provided with removable collars 27 made, for example, of rubber.

In order to maintain the chains 17 and 18 under tensile stress also in heavy weather, when the mooring buoy 1 is subject to large displacements in relation to the pipeline 4, the rigid pipe 6 is provided with a weight 28. Preferably each of the chains 17 and 18 is provided with a device 29 to enable the length of the chains 17 and 18 to be adjusted. To measure the tensile stresses in the chains 17 and 18 an electronic measuring device (not shown on drawing) may, if desired, be used.

Furthermore the chains 17 and 18 may be provided with a shock absorber (not shown in the drawings) in order to prevent the occurrence of too heavy shocks. Such a shock absorber is in particular desirable in regions where wide tidal ranges and very poor weather conditions may occur.

When a ship moored to the mooring buoy 1 bumps against the hose Sand the chains 17 and 18, for example owing to the wave movements, the combination of hose and chains will, as a result of its flexibility, bend away and therefore incur no damage from the collision.

Since the chains 17 and 18 invariably absorb the weight of rigid pipe 6, the hose 5 can be replaced in a rapid and simple manner.

It should be noted that instead of the chains 17 and 18 shown, another suitable flexible tension member, for example a cable, can be used.

It is further remarked thatthe invention is not limited to the combination of one hose and two chains or other flexible tension members. For example, a combination of two hoses and one tension member or combinations of several hoses and several tension members isiare also possible.

Instead of the weight 28, it is also possible to use other forms of ballast to maintain the tension members under tensile stress. In this connection reference is made, for example, to ballast tanks which are connected to the rigid pipe 6.

Finally, it is noted that the universal joints 8, 19 and 20, together with the rotatable coupling 25, can be replaced by other special couplings, for example ball joints.

Claims

1. A movable connecting conduit between a mooring buoy for fluid transfer and a submerged pipeline, characterized in that, seen from the mooring buoy in the direction of the pipeline, the connecting conduit is built up of at least one hose and at least one rigid pipe, which rigid pipe is movably connected to the pipeline, whilst at least one flexible tension member, which is under tensile stress, extends between the mooring buoy and the rigid pipe end located near the hose.

2. A movable connecting conduit as claimed in claim 1, characterized in that the tension member is attached to the mooring buoy and the rigid pipe by means of movable couplings.

3. A movable connecting conduit as claimed in claim 1 or 2, characterized in that means are present for maintaining the tension member under tensile stress.

4. A movable connecting conduit as claimed in claim 3, characterized in that the rigid pipe is provided with ballast for maintaining the tension member under tensile stress.

5. A movable connecting conduit as claimed in any one of the claims 1-4, characterized in that the tension member is provided with a device for adjusting the length of the tension member.

6. A movable connecting conduit as claimed in any one of the claims 1-5, characterized in that the tension member is provided with a shock absorber.

7. A movable connecting conduit as claimed in any one of the claims 1-6, characterized in that the outside of the hose is provided with protecting elements.

8. A movable connecting conduit as claimed in any one of the claims 1-7, characterized in that one hose and two flexible tension members extend between the mooring buoy and the rigid pipe.

9. A movable connecting conduit as claimed in any one of the claims 2-8, characterized in that the tension member is attached to the rigid pipe by means of a universal joint and to the mooring buoy by means of a universal joint, the latter universal joint being connected to the mooring buoy by means of a coupling rotatable around a vertical axis.

10. A movable connecting conduit as claimed in any one of the claims 1-9, characterized in that the flexible tension member is a chain.

11. A movable connecting conduit between a mooring buoy for fluid transfer and a submerged pipeline substantially as described in the patent specification with particular reference to the accompanying drawings.