GB2387188A

GB2387188A - Apparatus for attaching a fluid conduit to a structure

Info

Publication number: GB2387188A
Application number: GB0207832A
Authority: GB
Inventors: Baan Jacob De
Original assignee: Bluewater Terminal Systems NV; Bluewater Energy Services BV
Current assignee: Bluewater Energy Services BV
Priority date: 2002-04-04
Filing date: 2002-04-04
Publication date: 2003-10-08
Anticipated expiration: 2022-04-04
Also published as: GB2387188B; NO329888B1; NO20031514D0; NO20031514L; GB0207832D0

Abstract

A buoyant body 3 having a fluid conduit connected to a riser 4 is engaged with a floating vessel 1 by pulling the body 3 into a recess 6 formed in the vessel and activating locking means 9. A valve 13 on the fluid conduit is automatically closed during disengagement of the body 3 from the vessel 1 by a chain 17 attached to an actuation handle 16 of the valve 13 being pulled taut to rotate the handle 13 to the vertical position.

Description

2387 88

- 1 APPARATUS FOR ATTACHING A FLUID CONDUIT TO A STRUCTURE

The presentinvention relates to an apparatus for attaching fluid conduits, such as flexible risers, to 5 a structure, such as a floating vessel, via a buoyant body. In particular, the invention relates to means for automatically closing off the flow path upon disconnection of the buoyant body from the vessel.

10 It is known to attach the ends of flexible risers to a buoyant body which can itself be engaged with a floating vessel for transfer of fluids from the risers to the vessel. In such known systems, when it is desired to disconnect the buoyant body from the 15 vessel, it is first necessary to activate valves to close off the risers, by some means such as hydraulic, electrical or air-powered systems. Additionally, a coupler is usually incorporated to couple the flow paths in the risers to those in the vessel and this 20 also requires initiation and power to disengage. Only after the valves have been closed and the flow paths decoupled and separated can the buoyant body be released from the vessel.

25 The present invention provides apparatus for attaching a fluid conduit to a structure, comprising a buoyant body, at least one fluid conduit attached to the buoyant body, means to selectively engage the buoyant body with a structure, means to couple the 30 fluid conduit to a fluid receiving conduit on the structure for conveyance of fluid from the fluid conduit to the structure, and valve means operable selectively to open and close the fluid conduit, wherein upon disengagement of the buoyant body from 35 the structure actuation means is operable automatically to close the valve means and the means to couple is operable automatically to separate the

fluid conduit from the fluid receiving conduit.

In this way, a simple and failsafe disconnection mechanism is provided which ensures the fluid flow 5 paths are automatically sealed off and separated without the need for separate actuation.

Preferably, the means to engage the buoyant body with the structure comprises a recess in the structure 10 shaped to receive at least part of the buoyant body.

In a preferred embodiment, the recess is located in a turret rotatably mounted to the structure and, conveniently, a swivel arrangement is located on the 15 turret to provide a fluid flow path between the buoyant body and the structure.

The means to engage the buoyant body also preferably includes locking means to selectively lock 20 the buoyant body in the recess.

The means to engage the buoyant body to the structure may also comprise a pullwire mechanism attachable between the structure and the buoyant body 25 operable to pull the buoyant body into engagement with the structure.

The actuation means preferably comprises an actuation handle operable to move the valve means 30 between open and closed positions and a connection member connected between the structure and the actuation handle, whereby upon disengagement of the buoyant body from the structure the connection member displaces the actuation handle in a direction to close 35 the valve means.

Preferably, the connection member is a flexible

member, such as a chain, cable or wire.

In a preferred embodiment, the actuation means is arranged such that, upon disengagement of the buoyant 5 body from the structure, the buoyant body moves downwardly under gravity pulling the connection member taut, whereupon further downward movement of the buoyant body causes the connection member to displace the actuation handle.

The connection member is preferably designed to break at a load greater than that required to displace the actuation handle, in order to allow complete disengagement of the buoyant body from the structure.

Preferably, the means to couple the fluid conduit to the fluid receiving conduit comprises first and second members, each defining a bore therethrough, wherein the first member is received in the bore of 20 the second member in order to provide a continuous bore through the first and second members.

In particular, the first member may comprise a projection which is received in an enlarged portion of 25 the bore of the second member and seals may be provided between the projection and the enlarged portion. In a preferred embodiment, the first member is 30 provided on the end of the fluid conduits in the buoyant body and the second member is provided on the end of the fluid receiving conduits on the structure.

Typically, the structure comprises a floating 35 vessel and the fluid conduit comprises a flexible pipeline.

- 4 - The invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic view of the apparatus for 5 attaching a fluid conduit to a floating vessel in accordance with the present invention; Figure 2 is an enlarged view of part of the floating vessel and the means for engaging the buoyant body; 10 Figure 3a is a further enlarged view, partly in section, of the buoyant body when engaged with the vessel; Figure 3b is a further enlarged view, partly in section, of the top part of Figure 3a; and Figure 4 is a schematic diagram of the connecting sleeve between the buoyant body and the vessel.

As shown in Figure 1, a floating vessel maintains a position above a given point 2 on the sea bed, for 20 example by dynamic positioning means as well know in the industry.

A buoyant body 3, which may be partly or wholly submerged when not engaged with the vessel 1, is 25 connected to one or more fluid conduits, in particular flexible risers 4, which are attached to any structure 5 requiring the conveyance fluids. Structure 5 may be located above or under water, or on another vessel or on a platform on the sea bed. In this case, it is a 30 sea bed structure, such as a well head.

When it is desired to convey fluids from the risers 4 to the vessel 1, the buoyant body 3 is engaged with the vessel 1. As shown in Figure 2, this 35 is achieved by pulling the buoyant body 3 into a recess 6 formed in the vessel 1 by means of pullwire mechanism 7, which may be a chain, cable, wire or any

- s other convenient mechanism. The buoyant body 3 has a substantially cylindrical upward projection and the recess 6 is correspondingly shaped such that it may receive the upper part of the buoyant body 3. The 5 flared lower end of the recess 6 facilitates the location of the upward projection of the buoyant body 3 within the recess 6. When the buoyant body 3 is fully engaged within the recess 6, a locking means 9 is activated to lock the buoyant body 3 in position.

Preferably, the structure defining the recess 6 is a turret 18 fitted rotatably in the vessel 1 by means of a bearing arrangement 8, which may be located either above or below the waterline of the vessel.

As best seen in Figures 3a and 3b, the turret 18 is extended vertically with a number of substantially vertical support legs 10 and substantially horizontal support plates 11 which support a fully 360 swivel 20 arrangement 12, as is well known in the industry.

Connection of the flow paths between the buoyant body and the swivel arrangement 12 is effected by a coupling means such as a piping sleeve 14 seen in 25 Figure 4. The sleeve 14 is preferably configured as a spool piece consisting of two parts 14a and 14b with conventional seals 15 therebetween. The upper part 14a, shown in section in Figure 4, is mounted to the turret structure 18 and defines a bore 19. The lower 30 part 14b is mounted to the upper end of the buoyant body 3 and includes a projection 20 which is received in the bore 19. When connected together, the upper and lower parts 14a, 14b define a through-passage 21 to connect the flow paths in the buoyant body 3 to the 35 flow paths in the swivel arrangement 12. When the buoyant body 3 is disconnected from the vessel 1 by releasing the locking means 9, the two parts of the

sleeve 14 simply slide apart, thereby automatically separating the flow path in the buoyant body 3 from that in the vessel 1.

5 Referring back to Figures 3a and 3b, valve means 13 is provided in an upper part of the fluid conduit extending through the buoyant body 3, just below the sleeve 14. An actuation handle 16 operates the valve 13. In this example, the actuation handle 16 extends 10 substantially horizontally when the valve 13 is open and causes valve 13 to close if it is rotated approximately 90 clockwise to the vertical position.

A connection member 17, such a flexible chain, is 15 connected between the actuation handle 16 and the support structure 10, 11. When the buoyant body 3 is fully engaged with the vessel 1, the connection member 17 is slack.

20 When it is desired to disengage the buoyant 3 from the vessel 1, locking means 9 is released and the buoyant body 3 slides down the recess 6 under gravity and the two parts of sleeve 14 separate. As the buoyant body 3 moves downwardly, the connection member 25 17 first becomes pulled taut and then pulls actuation handle 16, causing it to rotate clockwise towards the vertical, thereby closing the valve 13.

At a predetermined load, which has a value 30 greater than the load required to displace the actuation handle 16 and close the valve 13, but much less than any value which could damage the valve 13, the connection member 17 breaks and the buoyant body 3 is fully released from the vessel 1 to sink to a 35 predetermined position above the sea bed.

It is to be noted that the axial pipe pressure

- 7 forces, which originate from the flow paths being under pressure, cannot be taken by the sliding sleeve 14 which would simply slide apart under these forces.

Therefore, the locking means 9, support structure 10, 5 11 and valve means 13 are designed to resist these loads, in addition to the vertical loads which originate from the weight of the various parts of the apparatus and the loads which are imposed by virtue of the apparatus being used at sea.

The skilled reader will appreciate that the present invention provides a simple mechanism for automatically disconnecting fluid conduits from a structure and automatically closing off the fluid flow 15 paths with no specific outside actuation required. It will also be appreciate that a number of modifications and variations to the precise details described can be employed, without departing from the scope of the claims. 20.

Claims

- 8 CLAIMS

1. Apparatus for attaching a fluid conduit to a structure, comprising a buoyant body, at least one 5 fluid conduit attached to the buoyant body, means to selectively engage the buoyant body with a structure, means to couple the fluid conduit to a fluid receiving conduit on the structure for conveyance of fluid from the fluid conduit to the structure, and valve means 10 operable selectively to open and close the fluid conduit, wherein upon disengagement of the buoyant body from the structure actuation means is operable automatically to close the valve means and the means to couple is operable automatically to separate the 15 fluid conduit from the fluid receiving conduit.

2. Apparatus as claimed in claim 1, wherein the means to selectively engage the buoyant body with the structure comprises a recess in the structure shaped 20 to receive at least part of the buoyant body.

3. Apparatus as claimed in claim 2, wherein the recess is located in a turret rotatably mounted to the structure. 4. Apparatus as claimed in claim 3, further comprising a swivel arrangement located on the turret to provide a flow path between the fluid conduit and the structure.

5. Apparatus as claimed in any of claims 2-4, further comprising locking means selectively to lock the buoyant body in the recess.

35 6. Apparatus as claimed in any preceding claim, further comprising pull wire mechanism attachable between the structure and buoyant body operable to

- 9 pull the buoyant body into engagement with the structure. 7. Apparatus as claimed in any preceding claim, 5 wherein the actuation means comprises an actuation handle operable to move the valve means between open and closed positions and a connection member connected between the structure and the actuation handle, whereby upon disengagement of the buoyant body from 10 the structure the connection member displaces the actuation handle in a direction to close the valve means. 8. Apparatus as claimed in claim 7, wherein the 15 connection member comprises a flexible member.

9. Apparatus as claimed in claim 8, wherein the flexible member is a chain, cable or wire.

20 10. Apparatus as claimed in any of claims 7-9, wherein the connection member is arranged such that upon disengagement of the buoyant body from the structure and subsequent downward movement of the buoyant body, the connection member is pulled taut, 25 and further downward movement of the body causes the connection member to displace the actuation handle.

11. Apparatus as claimed in any of claims 7-10, wherein the connection member is designed to break to 30 load greater than that required to displace the actuation handle and close the valve means, to allow complete disengagement of the buoyant body from the structure. 35 12. Apparatus as claimed in any preceding claim, wherein the means to couple the fluid conduit to the fluid receiving conduit comprises first and second

- 10 members, each defining a bore therethrough, wherein the first member is received in the bore of the second member to provide a continuous bore through both first and second members.

Apparatus as claimed in claim 12, wherein the first member further comprises a projection received in an enlarged portion of the bore of the second member.

10 14. Apparatus as claimed in claim 13, further comprising sealing means between the projection and the enlarged portion of the bore.

15. Apparatus as claimed in any of claims 12-14, 15 wherein the first member is provided on the end of the fluid conduit and the second member is provided on the end of the fluid receiving conduit.

16. Apparatus as claimed in any preceding claim, 20 wherein the structure comprises a floating vessel and the fluid conduit comprises a flexible pipeline.

17. Apparatus for attaching a fluid conduit to a structure substantially as hereinbefore described and 25 with reference to the accompanying drawings.