WO2015075555A1

WO2015075555A1 - Transfer mechanism

Info

Publication number: WO2015075555A1
Application number: PCT/IB2014/003036
Authority: WO
Inventors: Cédric MOUCHEL
Original assignee: Technip France
Priority date: 2013-11-21
Filing date: 2014-11-20
Publication date: 2015-05-28
Also published as: GB201320599D0; GB2520512B; GB2520512A

Abstract

The present invention relates to a transfer mechanism (28) for transferring a fitting (46) on a flexible tubular conduit (48) about a guiding means (26) of a pipelay tower (20). The transfer mechanism (28) comprises a transport collar assembly (32) connectable to a flexible tubular conduit (48) proximate a fitting (46) on the flexibly tubular conduit (48) and a conveyor assembly (29) engageable with the transport collar assembly (32). Actuation of the transfer mechanism (28) is configured activate the conveyor assembly (29) to engage with the transport collar assembly (32) and cause at least one part of a fitting (46) on a flexible tubular conduit (48) connected to the transport collar assembly (32) of the transfer mechanism (28) to move along a path outside a surface of the guiding means (26) from a first position upstream of the guiding means (26) to a second position downstream of the guiding means (26).

Description

TRANSFER MECHANISM

The present invention relates to a transfer mechanism, in particular, a transfer mechanism for transferring a fitting on a flexible tubular conduit.

The laying of flexible tubular conduits subsea is usually preformed from a suitable pipe-laying/pipelay vessel such as a floating platform, barge, ship or other vessel. The flexible tubular conduit may be one of many different forms. The flexible tubular conduit is preferably a flexible pipe of the unbounded type for conveying hydrocarbons as defined in the American Petroleum Institute Recommendations API17J "Specification for unbounded flexible tubular conduit". However, the flexible tubular conduit may be of the bonded type. The flexible tubular conduit may alternatively be an umbilical as defined in the American Petroleum Institute API17E "Specification for subsea umbilical" third Edition, 2003. Alternatively, the flexible tubular conduit may be an Integrated Production Bundle (IPB) described in the patent US6102077 and marketed by the applicant under the registered trademark ISU^® (Integrated Subsea Umbilical). The flexible tubular conduit is stored in a basket or on a reel on the deck of the vessel and in one method is fed from the basket/reel to a vertical pipelay tower, where it is vertically aligned prior to laying the flexible tubular conduit underwater.

Guiding means in the form of an aligner, a chute or a reel is positioned on the top of the pipelay tower and used to divert the flexible tubular conduit from a horizontal path to a vertical path for laying. The guiding means generally comprises a groove, channel or gutter for receiving the flexible tubular conduit and for facilitating the diverting of the flexible tubular conduit from the horizontal path to the vertical path. The pipelay tower further comprises tensioning means, for example pipe tensioners comprising one or more caterpillar tracks, to facilitate the feeding of the flexible tubular conduit along the required vertical path. In use, the tensioning means grip the flexible tubular conduit and help feed and deploy the flexible tubular conduit towards the seabed.

Before commencing the normal lay of the flexible tubular conduit, the first end of the flexible tubular conduit is engaged on the guiding means located on top of the pipelay tower and appropriately vertically aligned. The first end of the flexible tubular conduit is then guided along the vertical path, often referred to as the 'firing line' and through the tensioning means towards an opening, such a moon pool, on the deck of the vessel.

A normal procedure for getting the first end of the flexible tubular conduit onto the guiding means, and thereafter vertically aligned with the firing line involves the use of a initiation winch to lift the first end of the flexible tubular conduit onto the guiding means.

However, a flexible tubular conduit is generally provided with one or more fittings, such as an end fitting and/or stiffener, which generally have an outer diameter that is greater than the outer diameter of the flexible tubular conduit. As a result, a fitting located at the end of the flexible tubular conduit cannot easily navigate the guiding means in order to get the first end of the flexible tubular conduit vertically aligned with the firing line.

In cases where the first end of the flexible tubular conduit comprises a fitting attached thereto, the use of a deck crane or auxiliary winch is required in order to lift the fitting and position it downstream of the guiding means. This is because the fitting has a greater outer diameter than the flexible tubular conduit and as such cannot easily navigate the guiding means if just pulled by the initiation winch. Assistance of a vessel crane and men on the top of the pipelay tower is often required to guide the end fitting on the guiding means and to get it down the hole formed by the entrance of the upper tensioner. US 5348423 describes a method of laying a flexible tubular conduit according to the state of the art. A device is disclosed for laying flexible tubular conduits having a fitting, such as end fittings or the like, attached to the end thereof. The device comprises a main linear winch-type tensioning means for normal lowering of the flexible conduit to be laid and an auxiliary winch for lifting the fitting clear of the guiding means and into the tower when the outer diameter of the fitting is greater than the outer diameter of the conduit.

Hydrocarbons are now extracted from deeper seabed, and as a result there is a need to deploy longer lengths of flexible tubular conduit. Thus the capacity of the pipelay tower has to be increased.

To achieve this aim, larger tensioning means are required on the pipelay tower, for example moving from 1 or 2 tensioners to 3 or 4 tensioners within the tensioning means. This leads to an increase in the height of the pipelay tower as a tower having 4 tensioners will be almost twice the height of a tower having 2 tensioners.

In addition, as the flexible tubular conduit length increases, the end fitting becomes bigger and the stiffener becomes larger and longer in order to sustain the force exerted on it.

The need for bigger end fittings coupled with the increase in the height of the pipelay tower, means that methods currently known in the art are not very practical for transferring the fitting attached to the first end of the flexible tubular conduit over the guiding means. In particular, this would need a long boom vessel crane to reach the aligner reel and higher capacity crane. In addition assistance of men at this height for prolonged periods of time is not recommended for safety reasons.

There is therefore a need for a transfer mechanism and method which facilitates the transfer of a fitting attached to the first end of the flexible tubular conduit over the guiding means in the deployment of longer lengths of flexible tubular conduits. It is an object of the invention to provide an improved transfer mechanism and method for transferring a fitting attached to the end of a flexible tubular conduit about the guiding means of a pipelay tower. According to a first aspect, there is provided a transfer mechanism for transferring a fitting on a flexible tubular conduit about a guiding means of a pipelay tower, said transfer mechanism comprising:

a transport collar assembly connectable to a flexible tubular conduit proximate a fitting on the flexible tubular conduit; and

a conveyor assembly engageable with the transport collar assembly, wherein actuation of the transfer mechanism is configured to activate the conveyor assembly to engage with the transport collar and cause at least one part of a fitting on a flexible tubular conduit connected to the transport collar assembly of the transfer mechanism to move along a path outside a surface of the guiding means from a first position upstream of the guiding means to a second position downstream of the guiding means.

By means of the invention, the transfer of a fitting attached to the first end of the flexible tubular conduit over the guiding means in the deployment of longer lengths of flexible tubular conduits can be more easily achieved.

In addition, a transfer mechanism in accordance with the invention removes or reduces the need for the use of a deck crane or an auxiliary winch to move the end fitting on a flexible tubular conduit from a first position upstream of the guiding means to a second position downstream of the guiding means, as required in methods currently known in the art.

In addition, a transfer mechanism in accordance with the invention does not necessitate the assistance of men working at elevated heights for prolong periods of time. Another advantage of the transfer mechanism according to the invention is that the product minimum bending radius (MBR) of a flexible tubular conduit does not need to be exceeded at any time during the operation. Preferably, the path outside the surface of the guiding means is within a vertical plane defined by the guiding means. This prevents any over bending of the fitting.

Preferably, the transport collar assembly comprises a runner adapted to slide within a channel in the guiding means.

Preferably, the transport collar assembly comprises a clamp mechanism adapted to connect and secure the flexible tubular conduit to the transfer mechanism.

In exemplary embodiments wherein the transport collar assembly comprises a runner and a clamp mechanism, the clamp mechanism is preferably mounted on the runner.

Preferably, the conveyor assembly comprises a head portion and a frame portion, the head portion being coupled to the frame portion.

In exemplary embodiments, the frame portion is adapted to rotate about the guiding means.

Optionally, the head portion is adapted to engage with the transport collar assembly.

In exemplary embodiments, the head portion comprises a support for receiving a portion of a flexible tubular conduit therein. The transfer mechanism preferably further comprises actuation means for actuating the transfer mechanism. The actuation means may be any suitable device for rotating the frame portion about the guiding means. For example, the actuation means may be in the form of an electronic or hydraulic motor engageable with a large diameter ring gear attached to the frame portion of the conveyor assembly.

According to a second aspect, there is provided a pipelay tower comprising:

a guiding means for passing a flexible tubular conduit in a vertical direction; and

a transfer mechanism for transferring a fitting on a flexible tubular conduit about said guiding means, said transfer mechanism comprising a transport collar assembly and a conveyor assembly engageable with the transport collar assembly, wherein actuation of the transfer mechanism is configured to activate the conveyor assembly to engage with the transport collar and cause at least one part of a fitting on a flexible tubular conduit connected to the transport collar assembly of the transfer mechanism to move along a path outside a surface of the guiding means from a first position upstream of the guiding means to a second position downstream of the guiding means.

Preferably, the transfer mechanism forming part of the second aspect of the invention is a transfer mechanism according to the first aspect of the invention. The guiding means may be in any suitable form to facilitate the transfer of the flexible tubular conduit. For example, the guiding means may comprise an aligner, a chute, a reel or a wheel.

Preferably, the pipelay tower further comprises at least one tensioning means. The tensioning means may be in any suitable form as known in the art, for example, the tensioning means may comprise a pipe tensioner comprising one or more caterpillar tracks.

According to a third aspect, there is provided a pipelay vessel comprising a pipelay tower according to the second aspect of the invention. In exemplary embodiments, the pipelay vessel comprises storage means for storing a flexible tubular conduit.

The storage means may be in any suitable form for storing flexible tubular conduits. Preferably, the storage means comprises a basket.

According to a fourth aspect, there is provided a method of transferring a fitting on a flexible tubular conduit about a guiding means of a pipelay tower, comprising the steps of:

(a) connecting a transport collar assembly of a transfer mechanism to a flexible tubular conduit proximate a fitting on the flexible tubular conduit; and

(b) actuating the transfer mechanism to activate a conveyor assembly of the transfer mechanism to engage with the transport collar and cause at least one part of the fitting on the flexible tubular conduit to move along a path outside a surface of the guiding means from a first position upstream of the guiding means to a second position downstream of the guiding means.

Preferably, the transfer mechanism is a transfer mechanism according to the first aspect of the invention.

The invention will now be described by way of non-limiting example, with reference being made to the accompanying drawings, in which:

Figure 1 is a schematic view of an embodiment of a pipelay vessel in accordance with an aspect of the invention;

Figure 2 is a perspective view of an embodiment of a transport collar assembly forming part of a transfer mechanism in accordance with an aspect of the invention; Figure 3 is a perspective view of an embodiment of a conveyor assembly forming part of a transfer mechanism in accordance with an aspect of the invention; Figure 4 is a perspective view showing a first embodiment of a transfer mechanism in accordance with an aspect of the invention mounted on top of a pipelay tower;

Figure 4a is an enlarged view of the area indicated by A in figure 4;

Figure 5 is a partial cross-sectional view of the transfer mechanism and pipelay tower shown in figure 4;

Figure 6 is a perspective view of the embodiment of figure 4 showing the engagement of conveyor assembly with the transport collar assembly;

Figure 6a is an enlarged view of the area indicated by B in figure 6;

Figure 7 is a perspective view of the embodiment of figure 4 with the conveyor assembly and the transport collar assembly cooperating to move the fitting on the flexible tubular conduit about the guiding means;

Figure 7a is an enlarged view of the area indicated by C in figure 7; Figure 8 is a perspective view of the embodiment of figure 4 showing the fitting on the flexible tubular conduit moved by the transport collar assembly downstream of the guiding means;

Figure 8a is an enlarged view of the area indicated by D in figure 8;

Figure 9 is a perspective view of the embodiment of figure 4 showing the transport collar assembly disengaged from the conveyor assembly; and

Figure 9a is an enlarged view of the area indicated by E in figure 9.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application. Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Features, integers or characteristics, compounds described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. Referring to figure 1, an embodiment of a pipelay vessel 10 in accordance with an aspect of the invention is shown.

The vessel 10 comprises a deck 12 on which is positioned a storage means 14 for storing a flexible tubular conduit 48 and an initiation winch 16. In the embodiment shown, the storage means 14 is in the form of a basket although it may take any suitable form. For example, the storage means 14 may comprise a reel.

The vessel 10 further comprises a moon pool 18 and an associated pipelay tower 20. The pipelay tower 20 is in the form of a vertical pipelay tower.

The pipelay tower 20 comprises at least one tensioning means 22 associated therewith. The at least one tensioning means 22 is provided to facilitate the feeding of a flexible tubular conduit, such as a flexible pipe, along the firing line for laying the flexible tubular conduit.

In the embodiment shown, the tensioning means 22 is in the form of pipe tensioners 23 comprising one or more caterpillar tracks 24 as known in the art. While three tensioners 23 are shown, it would be understood that the tensioning means 22 may comprise more or less than three tensioners.

Each tensioner 23 of the tensioning means 22 is moveable between a first extracted position and a second stowed position such that the each tensioner 23 of the tensioning means 22 is retractable from the firing line of the flexible tubular conduit 48.

Guiding means 26 are located on top of the pipelay tower 20 to facilitate the diversion of the flexible tubular conduit 48 from a horizontal path to a vertical path for laying. The guiding means 26 comprises a channel 23 (not shown in figure 1) for receiving the flexible tubular conduit 48 therein. In the embodiment shown in figure 1, the guiding means 26 is in the form of a reel although it would be understood that the guiding means 26 may take any other suitable form, for example the guiding means 26 may be in the form of an aligner or a chute.

A transfer mechanism 28 is provided for engagement with the guiding means 26. The transfer mechanism 28 is configured to facilitate the transfer a fitting 46 on the flexible tubular conduit 48 about the guiding means 26.

The transfer mechanism 28 comprises a transport collar assembly 32 connectable to the flexible conduit 48 proximate the fitting 46 on the flexible tubular conduit 48.

The transport collar assembly 32 comprises a runner 33 adapted to slide within the channel 23 in the guiding means 26. The channel 23 provides a track along which the runner 33 runs and moves about the guiding means 26. The transport collar assembly 32 further comprises a clamp mechanism 34 adapted to connect and secure the flexible tubular conduit 48 to the transfer mechanism 28.

Referring to figure 2, an embodiment of the transport collar assembly 32 is shown. The clamp mechanism 34 is in the form of a conduit clamp and is mounted on the runner 33. The clamp mechanism 34 comprises a pair of spaced apart padeyes 40, each located at a distal end thereof.

The runner 33 is shaped and sized to fit within the channel in the guiding means 26. The runner 33 may be made from any suitable material that would facilitate the movement of the runner 33 within the channel. For example, the runner 33 may be made from a composite material, a plastics material, fibre glass, a rubber material or a metallic material. The transport collar assembly 32 further comprises a link 38 for connecting a winch cable 50 thereto. The link 38 may be positioned on the runner 33 or the clamp mechanism 34. In the embodiment shown, the link 38 is positioned on the runner 33. The transfer mechanism 28 further comprises a conveyor system 29 comprising a head portion 31 and frame portion 30.

The head portion 31 is adapted to engage with the transport collar assembly.

The frame portion 30 is adapted to rotate about the guiding means 26. The frame portion 30 comprises a longitudinal length that is approximately equal to a maximum radius of the guiding means 26. That is to say the longitudinal length of the frame portion 30 is approximately equal to a distance defined by the length from the midpoint of the diameter of the guiding means 26 to a circumference of or outer boundary of the guiding means 26.

Figure 3 depicts an embodiment of the conveyor assembly 29 in accordance with the invention. In the embodiment shown, the frame portion 30 is in the form of two parallel Y-shaped arms 36 and the head portion 31 is coupled to the branches of the Y-shaped arms 36 at the distal end thereof. Each Y-shaped arm 36 comprises a padeye 44 on a brank thereof. The head portion 31 is in the form of trough-shaped slider 42 and comprises a support 43 in the form of a cradle for receiving a portion of the flexible tubular conduit therein. In use, the cradle 43 supports a portion of the flexible tubular conduit proximate the transport collar assembly 32. The slider 42 is shaped and sized such that a least a bottom portion thereof is receivable within the channel 23 of the guiding means 26.

The frame portion 30 is pivotably mounted to the guiding means 26 such that actuation of the transfer mechanism 28 is configured to activate the conveyor assembly 29 and cause the frame portion 30 to rotate about the guiding means 26. This will cause the head portion 31 of the conveyor assembly to engage with the transport collar assembly 32 when the transport collar assembly 32 is positioned within the channel 23 if the guiding means 26. As a result, at least one part of a fitting 46 on the flexible tubular conduit 48 connected to the transport collar assembly 32 of the transfer mechanism 28 would move along a path outside a surface of the guiding means 26 from a first position upstream of the guiding means 26 to a second position downstream of the guiding means 26 as the frame portion 30 rotates about the guiding means 26.

The transfer mechanism 28 further comprises actuation means (not shown) for actuating the conveyor assembly 29 of the transfer mechanism 28. The actuation means may be any suitable device for rotating the frame portion 30 about the guiding means 26. For example, the actuation means may be in the form of an electronic or hydraulic motor engageable with a large diameter ring gear attached to the frame portion 30. While not specifically described or shown, the pipelay vessel 10 may comprise one or more features which are commonly incorporated in pipelay vessels known in the art, for example work table(s), access platform(s) etc. The method of transferring a fitting 46, in the form of an end fitting and attached bend stiffener (herein after referred to as "end fitting assembly" for simplicity), on a flexible tubular conduit 48 about the guiding means 26 of the pipelay tower 20 will now be described with particular reference to figures 4 to 9a. Only the top portion of the pipelay tower 20 is shown for clarity. The flexible tubular conduit 48 is shown in the form of a flexible pipe for conveying hydrocarbons.

A first end of the flexible tubular conduit 48 is first removed from the basket 14 and the end fitting assembly 46 connected thereto. It would be understood that the end fitting assembly 46 may be connected to the end of the flexible tubular conduit 48 prior to storage of the flexible tubular conduit 48 in the basket 14.

The transport collar assembly 32 is then connected to the flexible tubular conduit 48 proximate the end fitting assembly 46 by means of the clamp mechanism 34. The transport collar assembly 32 may be connected to flexible tubular conduit 48 prior to storage of the flexible tubular conduit 48 in the basket 14.

The conveyor assembly 29 is placed in a 'parked' position wherein the frame portion 30 is positioned in a substantially horizontal orientation (see figure 4) and the winch cable 50 is then fed from the initiation winch 16 along the path of the firing line, over the guiding means 26 and to the deck 12 of the vessel 10 where it is connected to the link 38 of the transport collar assembly 32, as shown in figure 1.

The free end of the end fitting assembly46 is then connected to an auxiliary winch or support crane (not shown) by an auxiliary cable 60 (see figure 5). The auxiliary winch or support crane provides support for the end fitting assembly 46 and helps to bear some or all of the weight of the end fitting assembly 46 during the transfer of the end fitting assembly 46 from a position upstream to a position downstream of the guiding means 26.

Once the auxiliary cable 60 is connected to the end fitting assembly 46 and the winch cable 50 connected to the link of the of transport collar assembly 32, the winch cable 50 is then rewound by the initiation winch 16. As the winch cable 50 is wound in by the initiation winch 16, the end fitting assembly 46 will be lifted upwards and towards the guiding means 26. The end fitting assembly 46 is lifted upwards to follow a substantially linear path. Due to the fact that the transport collar assembly 32 is connected to the winch cable 50, the runner 33 of the transport collar assembly 32 will be drawn into the channel 23 of the guiding means 26 as the winch cable 50 is rewound. At this point, the end fitting assembly 46 will have been lifted to a height above the central axis of the guiding means 26 (see figures 4, 4a and 5).

The actuation means is then engaged and initiated to cause the frame portion 30 to rotate about the guiding means 26 so that the head portion 31 of the conveyor assembly 29 comes into contact with the transport collar assembly 32 as shown in figures 6 and 6a.

The conveyor assembly 29 is then rigged to the transport collar assembly 32 (see figure 6a) via their respective padeyes 40,44. Once rigged, the actuation means is disengaged such that the drive is disconnected from the conveyor assembly 29 to allow the motor to free-wheel and allow the frame portion 30 to be driven by the movement of the transport collar assembly 32.

The initiation winch is then set into constant tension mode and further rewinding of the winch cable 50 will pull the transport collar assembly 32, and hence the end fitting assembly 46, towards the initiation winch 16. As the conveyor assembly 29 is now connected to the transport collar assembly 32, the conveyor assembly 29 will move with the transport collar assembly 32.

As the winch cable 50 is rewound, it will move the transport collar assembly 32 around the guiding means 36 resulting in the transfer of the end fitting assembly 36 and the flexible tubular conduit in a downstream direction as shown in figures 7 and 7a.

The support 43 of the head portion 31 of the conveyor assembly 29 helps maintain the minimum bend radius of the flexible tubular conduit 48.

As the runner 33 of the transport collar assembly 32 slides within the channel 23 about the guiding means 26, it will cause at least one part of the end fitting assembly 46 to move along a path outside a surface of the guiding means 26 from a first position upstream of the guiding means 26 (as shown in figure 4) to a second position downstream of the guiding means 26 (as shown in figure 8). The path outside the surface of the guiding means 26 is within a vertical plane defined by the guiding means 26. Once the end fitting assembly 46 is located downstream of the guiding means 26 and orientated in the vertical path of the firing line (see figure 8), the actuation means is reengaged with the conveyor assembly 29 and will hold the conveyor assembly 29 in position in order to allow the rigging to be removed. Once the rigging is removed, the auxiliary cable 60 is disconnected from the end fitting assembly 46 and the conveyor assembly 29 returned to the parked position by the activation means. The load is then transferred back to the initiation winch, which is re-set into drive mode. The end fitting assembly 46 may then be moved along the firing line by the rewinding of the initiation winch 16 as known in the art. Once the end fitting assembly 46 is secured in the tensioners, the initiation winch can be removed. While the invention has been described with reference to the laying of flexible tubular conduits in the form of flexible tubular conduits for conveying hydrocarbons, it would equally be applicable to the laying of other flexible tubular conduits, for example power cables, data cables etc.

While the invention has been described with reference to the utilization of an adapter to connect a fitting to the transfer mechanism, the clamp mechanism may be configured to clamp onto a portion of the fitting directly.

Claims

1. A transfer mechanism for transferring a fitting on a flexible tubular conduit about a guiding means of a pipelay tower, said transfer mechanism comprising: a transport collar assembly connectable to a flexible tubular conduit proximate a fitting on the flexible tubular conduit; and

2. A transfer mechanism according to claim 1 wherein the path outside a surface of the guiding means is within a vertical plane defined by the guiding means.

3. A transfer mechanism according to claim 1 or claim 2 wherein the transport collar assembly comprises a runner adapted to slide within a channel in the guiding means.

4. A transfer mechanism according to any one of the preceding claims wherein the transport collar assembly comprises a clamp mechanism adapted to connect and secure the flexible tubular conduit to the transfer mechanism.

5. A transfer mechanism according to claim 4 when dependent on claim 3, wherein the clamp mechanism is mounted on the runner.

6. A transfer mechanism according to any one of the preceding claims wherein the conveyor system comprises a head portion and a frame portion, the head portion being coupled to the frame portion.

7. A transfer mechanism according to claim 6 wherein the frame portion is adapted to rotate about the guiding means.

8. A transfer mechanism according to claim 6 or claim 7 wherein the head portion is adapted to engage with the transport collar assembly.

9. A transfer mechanism according to claim 8 wherein the head portion comprises a support for receiving a portion of a flexible tubular conduit therein.

10. A pipelay tower comprising:

11. A pipelay tower according to claim 10 wherein the transfer mechanism is a transfer mechanism according to any one of claims 1 to 9.

12. A pipelay tower according to claims 10 or claim 11 wherein the guiding means comprises an aligner, a chute, a reel or a wheel.

13. A pipelay tower according to any one of claims 10 to 12, further comprising at least one tensioning means.

14. A pipelay vessel comprising a pipelay tower according to any one of claims 9 to 12.

15. A pipelay vessel according to claim 13 further comprising storage means for storing a flexible tubular conduit.

16. A pipelay vessel according to claim 14 wherein the storage means comprises a basket.

17. A method of transferring a fitting on a flexible tubular conduit about a guiding means of a pipelay tower, comprising the steps of:

(b) actuating the transfer mechanism to activate a conveyor assembly of the transfer mechanism to engage with the transport collar and cause at least one part of the fitting on the flexible tubular conduit connected to the transport collar assembly of the transfer mechanism to move along a path outside a surface of the guiding means from a first position upstream of the guiding means to a second position downstream of the guiding means.

18. A method according to claim 17 wherein the transfer mechanism is a transfer mechanism according to any one of claims 1 to 9.