GB2591786A

GB2591786A - Flexible-elongate-element clamp

Info

Publication number: GB2591786A
Application number: GB2001634.1A
Authority: GB
Inventors: Arthur Brown Stephen; Thomas Leslie Colin; Preston Ewan
Original assignee: Maats Tech Ltd
Current assignee: Maats Tech Ltd
Priority date: 2020-02-06
Filing date: 2020-02-06
Publication date: 2021-08-11
Anticipated expiration: 2040-02-06
Also published as: GB202001634D0; GB2591786B; WO2021156606A1

Abstract

A flexible-elongate-element clamp 12 for holding a flexible-elongate element 18 when overboarding or onboarding the flexible-elongate element 18 from or to a vessel (14, fig 1). The clamp 12 comprises at least two pivotal clamp elements 26 for clamping the flexible elongate element 18 therebetween. Each clamp element 26 has a clamping surface 28 and at least one of the clamp elements 26 is expandable from a non-clamping condition to a clamping condition so that in use the flexible elongate element 18 is clamped between the clamping surfaces 28. At least one of the clamping surfaces 28 is flexible. A guide device 50 is fixed relative to a support 24 and comprises two offset guides. Reference is also made to a method of reducing deck space required for holding a flexible elongate element relative to a vessel and to a method of raising or lowering a flexible elongate element without requiring the use of a flexible-elongate-element tensioner.

Description

Flexible-Elongate-Element Clamp The present invention relates to a flexible-elongate-element clamp, in particular a vessel-supportable flexible-elongate-element clamp. The invention further relates to a flexibleelongate-element clamp assembly, a flexible-elongate-element clamp system and methods of holding and raising or lowering a flexible elongate element whilst preventing or limiting damage being caused to said flexible-elongate-element.

Flexible elongate elements are laid from vessels into the water, and especially onto the ground beneath the water, or seabed, to connect two locations which are separated by water.

Flexible elongate elements are typically laid continuously from the vessel, with the weight of the flexible elongate element in the water and above the seabed providing force to draw the flexible elongate element from the vessel. During the continuous laying, if necessary, a deck tensioner can usually provide sufficient restraining force to control the descent of the flexible elongate element to the seabed.

However, it can be required to halt the continuous laying, for example in the instance of equipment maintenance or rough seas. Thus, the flexible elongate element is required to be stopped, or substantially stopped, from moving. The deck tensioner may require maintenance during the laying operation and so would be unable to provide sufficient force to stop the flexible elongate element from descending, for example if taken off-line.

Additionally, it may be uneconomical or impractical to use the deck tensioner for halting the flexible elongate element for extended periods of time.

For laying in relatively shallow water, such as off-shore laying, Kellems (RTM) grips or "Chinese finger" grips are commonly used. Such grips include wires which wrap around the flexible elongate element to grip the flexible elongate element via frictional engagement therewith. The wires can then be restrained relative to the deck of the vessel to hold the flexible elongate element. However, Kellems (RTM) grips can be difficult and time consuming to apply to the flexible elongate element, requiring highly skilled deckhands. Additionally, for laying in deeper water, the additional weight of flexible elongate element can result in frictional forces which damage the outside of the flexible elongate element. For example, the wires can perforate or score the flexible-elongateelement sheath.

Rigid clamps which clamp around the exterior of oil or gas flexible pipelines are known for deep water application. However, such rigid clamps can damage more fragile flexible elongate elements, such as power cables, if used therewith due to the large point-loads which the rigid clamps apply. Due to an increasingly delocalised global power supply, power cables are more frequently required to span deep water.

Therefore, a clamp which can be quickly deployed to hold delicate flexible elongate elements without damage is required.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the present invention, there is provided a flexible-elongate-element clamp for holding a flexible-elongate element when overboarding or onboarding the flexible-elongate element from or to a vessel, the clamp comprising: at least two clamp elements for clamping the flexible elongate element therebetween, each clamp element having a clamping surface and at least one of the clamping surfaces being flexible; at least one of the clamp elements being expandable from a non-clamping condition to a clamping condition so that in use the flexible elongate element is clamped between the clamping surfaces.

Using at least one expandable clamp element, and in particular an inflatable clamp element, allows for a more even and better distributed clamping force to be applied to the flexible elongate element. This prevents or limits high point loads from being applied and thus prevents or limits damage to more delicate submersible flexible elongate elements, such as power cables. Having a pliable or flexible clamping surface additionally assists with better distributing the clamping force. Such an arrangement can also be applied to the flexible elongate element when submersed, rather than the application of Kellems (RTM) grips which is done manually on deck. This arrangement can therefore save deck space on a vessel.

Preferably, the clamp may further comprise a clamp housing including two clamp-housing members, each clamp-housing member for receiving at least one clamp element. A clamp housing can protect and contain the clamp elements, which may prevent or limit the expandable or inflatable clamp element from becoming perforated or otherwise damaged.

Advantageously, at least two of the clamp elements may be separable from each other to define a flexible-elongate-element-receiving opening for laterally receiving the flexible elongate element between the clamping surfaces. Therefore, the clamp can be positioned around a length of flexible elongate element without requiring an end of the flexible elongate element to be fed through the clamp.

Beneficially, at least one of the clamp elements may be pivotal relative to the other at at 5 least one hinge axis. Pivoting, rather than translating, the clamp elements can be simpler and easier to achieve.

In a preferable embodiment, the clamp elements may be pivotal at separate hinge axes. Separate hinge axes can allow for a greater separation of the clamp elements.

Additionally, the clamp may further comprise at least one guide for directing the flexible elongate element or the clamp so that the flexible elongate element is received through the flexible-elongate-element-receiving opening. A guide helps to ensure the flexible elongate element is correctly positioned. This may prevent or limit the clamp housing closing onto, rather than around, the flexible elongate element, and therefore preventing damage thereto.

Optionally, the or each guide may be moveable for engaging the flexible elongate element and creating relative movement between the flexible elongate element and the clamp to receive the flexible elongate element in a clamping position. A moveable guide allows for the flexible elongate element to be automatically received in position.

Preferably, there may be two guides. Two guides, such as two guide arms which project 20 in different radial directions relative to the flexible elongate element, allow for the clamp and/or flexible elongate element to be guided when at various positions Advantageously, the guides are offset from each other. Offset guides, such as guides which are offset in a longitudinal or axial direction, may allow for overlapping if the guides are moveable.

Beneficially, a plurality of the clamp elements is expandable from a non-clamping condition to a clamping condition. In a preferable embodiment, a plurality of the clamping surfaces is flexible.

Additionally, the number of clamp elements may be greater than or equal to three. A minimum of three clamp elements may prevent or limit the flexible elongate element from 30 moving once clamped.

Optionally, the number of clamp elements may be greater than or equal to six.

Preferably, the clamp may be elongate along a direction of the clamping surface. An elongate clamp and/or clamping surface can allow for a reduction in clamping pressure, whilst still providing sufficient holding force.

Advantageously, a longitudinal extent of the clamp may be greater than or equal to 2 metres. Beneficially, a longitudinal extent of the clamp may be greater than or equal to 3 metres. Additionally, a longitudinal extent of the clamp may be greater than or equal to 7 metres or 15 metres. Such values may allow for the clamp to provide sufficient holding force to hold the flexible elongate element in deep water without applying a clamping pressure which could damage the flexible elongate element.

Preferably, said at least one clamp element is inflatable from the non-clamping condition to the clamping condition.

In a preferable embodiment, the clamp further comprises a pump for pumping fluid surrounding the clamp to inflate said clamp element. In this way, seawater surrounding the clamp can be used to inflate the clamp elements. As such, a chamber or pipeline of inflation fluid is not required.

Additionally, the clamp may further comprise a suspension means for suspending the clamp housing from the vessel. Therefore, the clamp can be suspended in the sea and a longer clamp can be utilised due to the clamp not being subject to deck space restrictions. As such, clamping forces can be dispersed along a longer length and so less clamping pressure is applied to the flexible elongate element.

Preferably, the suspension means may comprise a flexible elongate member.

According to a second aspect of the present invention, there is provided a flexibleelongate-element-clamp assembly comprising: at least one flexible-elongate-element clamp according to a first aspect of the invention; and a support for supporting and receiving the or each clamp. A support can protect the clamp from damage and allows for the clamp to be mounted thereto.

Preferably the assembly may further comprise a plurality of clamps supportable and receivable by the support along the flexible-elongate-element path. A plurality of clamps, for example provided as clamp modules, may allow for a holding force to be more easily 30 customised.

Advantageously, the support may have a U-shaped or substantially U-shaped cross-section which defines a channel for receiving the or each clamp therein.

According to a third aspect of the present invention, there is provided a flexible-elongateelement-clamp system comprising: a power or signal transmission cable; a flexibleelongate-element clamp according to the first aspect of the invention, the clamp arranged to clamp the power or signal transmission cable.

According to a fourth aspect of the present invention, there is provided a method of reducing deck space required for holding a flexible elongate element relative to a vessel, the method comprising; a) suspending a flexible-elongate-element clamp preferably according to a first aspect of the invention; b) receiving a flexible elongate element between the clamping surfaces of said clamp; c) expanding at least one of the clamp elements from a non-clamping condition to a clamping condition to hold the flexible elongate element between the clamping surfaces.

According to a fifth aspect of the present invention, there is provided a method of raising or lowering a flexible elongate element along a flexible-elongate-element path without requiring the use of a flexible-elongate-element tensioner, the method comprising: a) providing a first and second flexible-elongate-element clamp preferably according to the first aspect of the invention, each suspended from the same or separate vessels; b) clamping the flexible elongate element with a first clamp and raising the flexible elongate element by raising the first clamp to a higher position along the flexible-elongate-element path; c) clamping the flexible elongate element with the second clamp to hold the flexible elongate element; and d) unclamping the first clamp.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a side view of a first embodiment of a vessel-supportable flexibleelongate-element-clamp assembly according to a second aspect of the invention, having a first embodiment of a vessel-supportable flexible-elongate-element clamp according to a first aspect of the invention, suspended from a vessel and aligned along a flexibleelongate-element path of a flexible elongate element being overboarded from the vessel; Figure 2 shows a perspective view of the vessel-supportable flexible-elongateelement assembly of Figure 1 illustrating two vessel-supportable flexible-elongate-element clamps, an upper clamp in a clamping condition with a clamp housing closed and the clamp elements expanded and a lower clamp being in a non-clamping condition with the clamp housing open; Figure 3 shows a top view of a vessel-supportable flexible-elongate-element clamp of Figure 1 in a closed condition; Figure 4 shows a top view of a vessel-supportable flexible-elongate-element clamp of Figure 1 in a closed and clamping condition; Figure 5 shows two first embodiments of a vessel-supportable flexible-elongate-element-clamp assembly, a lower vessel-supportable flexible-elongate-element-clamp assembly being in a lowered condition; Figure 6 shows the vessel-supportable flexible-elongate-element-clamp assemblies of Figure 5, the lower vessel-supportable flexible-elongate-element-clamp 10 assembly being in a raised condition; Figure 7 shows a second embodiment of a vessel-supportable flexible-elongate-element-clamp assembly with two vessel-supportable flexible-elongate-element clamps in an open condition, positioned on a deck of a vessel; Figure 8 shows the vessel-supportable flexible-elongate-element-clamp assembly of Figure 7 in a closed condition; Figure 9 shows three first embodiments of the clamping assembly, a first and second clamping assembly at a first leg of a loop or bight of flexible elongate element, 20 and a third clamping assembly at a second leg of the loop or bight of flexible elongate element, the second clamping assembly being in a lowered condition; Figure 10 shows the arrangement of Figure 9, with the second clamping assembly in a raised condition.

Figure 11 shows a representation of a third embodiment of a vessel-supportable 25 flexible-elongate-element clamp in an open condition; and Figure 12 shows the vessel-supportable flexible-elongate-element clamp of Figure 11 in a closed condition.

Referring firstly to Figure 1, there is shown a first embodiment of a vessel-supportable flexible-elongate-element-clamp assembly 10. The clamp assembly 10 comprises two vessel-supportable flexible-elongate-element clamps 12 and is shown in use suspended from a vessel 14 via a suspension element, not shown. The clamp assembly 10 is positioned along a flexible-elongate-element path 16 which is defined by a path of movement of a flexible elongate element 18 when being overboarded.

Here the clamp assembly is positioned in the water 20, and thus may be referred to as a sub-sea or submersible clamp assembly. Thus, the clamp assembly 10 is positioned offboard, outboard or overboard of the vessel 14. It will be appreciated that the clamp assembly 10 or clamp 12 may be positioned out of the water 20 so as to be suspended in the air, or part in the water 20 and part out of the water 20.

The vessel 14 comprises an overboarding chute 22 for overboarding the flexible elongate element 18 from the vessel 14 and it will be appreciated that the clamp assembly 10 may be suspended from the overboarding chute 22 or any other overboarding device.

However, the clamp assembly 10 may be suspended from other parts of the vessel 14, such as from the deck 14a, from the hull 14b, or from a crane 14c or other support which may project from the deck 14a.

Referring to Figure 2, the clamp assembly 10 preferably comprises two clamps 12, although only a single clamp 12 may be considered or any number of clamps 12. The clamps 12 are linearly aligned to receive a flexible elongate element 18 therethrough. The assembly 10 further comprises a support 24, for supporting the clamps 12. Here the support 24 comprises a frame or a cage, although a support 24 formed from continuous walls may also be considered. The support 24 may protect the clamps 12 from damage, and/or may provide a structure for mounting the clamps 12 thereto. Here the support 24 is U-shaped or substantially U-shaped such that it defines a channel for receiving the clamps 12. For example, the support 24 may have a rear wall 24a and two projecting side walls 24b for receiving the clamp 12 therebetween.

Each clamp 12 preferably has a longitudinal extent of between 2 m and 6 m and more preferably has a longitudinal extent of 4 m. Each clamp 12 may have a separate portion of support 24c associated therewith. Therefore, one clamp 12 and associated support portion 24c may form a clamp assembly module 10a. Multiple clamp assembly modules 10a may be interconnected or inter-attached. For example, the clamp assembly 10 as shown comprises three clamp assembly modules 10a. The total length of the clamp assembly 10 or clamp 12 may be greater than 8 m, for example being greater than or equal to 15 m.

Each clamp 12 comprises at least two clamp elements 26 each having a clamping surface 28 for clamping the flexible elongate element 18 therebetween. At least one of 5 the clamp elements 26 is expandable or inflatable from a non-clamping condition to a clamping condition. In this way at least one of the clamping surfaces 28 is proximal to the flexible elongate element 18, or flexible-elongate-element path 16, when in the clamping condition relative to the non-clamping condition. At least one of the clamping surfaces 28 is pliable, flexible, pliant or pliably flexible. In this way, the clamping surface 10 28 may be depressible.

The clamp 12 further comprises a clamp housing 30 for receiving the clamp elements 26. The clamp housing 30 has two clamp-housing members 32. The clamp housing 30 is openable to define a flexible-elongate-element-receiving opening 34 along an axial extent thereof. At least one of the clamp-housing members 32 is pivotal relative to the other at a hinge axis which is parallel with the axial extent of the flexible-elongateelement path 16. Here both clamp-housing members 32 are pivotable, and together they may be considered to be a pair of jaws for closing around the flexible elongate element 18. Referring to Figure 3, each clamp-housing member 32 has a separate pivot axis 36. However, it will be appreciated that the clamp-housing members may each have the same pivot axis, in other words their pivot axis may be co-linear or aligned. Each clamp-housing member 32 is preferably semi-cylindrical, having a semi-circular cross-section, so that the clamp housing 30, when closed, is cylindrical. However, it will be appreciated that other shapes may be considered for example cuboidal housings.

Each clamp-housing member 32 is preferably actuatable or moveable about its pivot, for 25 example, each clamp-housing member 32 may be mechanically moveable by an actuator such as a piston, motor or similar mechanical mechanism.

The clamp housing 30 defines a void, space or receiving volume for receiving the clamp elements 26 and the flexible elongate element 18. Each end or flange 38 of the housing 30 has an aperture 40 therein for receiving the flexible elongate element 18 therethrough.

Each clamp-housing member 32 defines a part of, and here half of the aperture 40. The apertures 40 are preferably circular, and thus the shape of the aperture 40 preferably corresponds to a cross-section of the flexible elongate element 18. The flexibleelongate-element path 16 extends through the receiving volume and between the apertures 40, and thus a path between the apertures 40 through the void may at least in part define the flexible-elongate-element path 16 when the flexible elongate element 18 is received therein.

The clamp housing 30 preferably has a continuous side wall; however, it will be appreciated that the clamp housing 30 may be framework. The clamp housing 30 here has ribbing 46 around a circumferential extent thereof, although it will be appreciated that this may not be included. Additionally, each clamp housing 30 preferably has an axially extending flange 42, the axially extending flanges 42 being engageable with each other to close the clamp housing 30.

The clamp housing 30 preferably includes a locking element 44 for locking the two clamp-housing members 32 together in a closed condition. Here the locking element 44 comprises at least one hole 44a on each of the clamp-housing member 32. A U-shaped locking bolt or similar may be inserted through the holes so as to lock the clamp-housing members together. There may be multiple pairs of holes, with separate locking bolts, or the pairs of holes may be aligned so that a single U-shaped locking bolt may be inserted through all of the holes.

Alternatively, the locking element may comprise at least one projection on each clamp-housing member and at least one receiver. The projections are aligned with each other in an axial direction of the flexible-elongate-element path, and the receiver has an opening sized to receive both projections. The receiver has side walls arranged to prevent or limit movement of the projections received therebetween away from each other. Each projection extends from a rib of the ribbing and/or the axially extending flange, although the projections may extend from other positions on the clamp housing. Each projection is hook-shaped, crescent-shaped, substantially hook-shaped, substantially crescent shaped, and an outward end of each projection preferably extends in a direction away from the other projection. However, it will be appreciated that this may not be the case. Additionally, it will be appreciated that other locking elements or mechanisms may be considered, for example locking bolts. There may be multiple pairs of projections and multiple receivers, each receiver configured to receive each pair of projections. Preferably, the receivers are connected together so as to be operable simultaneously.

Whilst a housing 30 is described and shown for receiving the clamp elements 26, it will be appreciated that a housing may be omitted and instead the clamp elements may instead be held in position, for example at each end.

There are preferably sufficient clamp elements 26 to maintain the position of the flexible 5 elongate element 18, for example there may be a minimum of three clamp elements 26. The clamp elements 26 oppose each other and are on opposing sides of the flexible elongate element 18. Here there are six clamp elements 26, and three clamp elements 26 are received within each clamp-housing member 30. Whilst separate clamp elements 26 are described, it will be appreciated that a single inflatable device may be considered, 10 such as an inflatable device with an annular cross-section, with the inflatable device being required to be received axially therethrough, or a C-shaped cross-section.

Preferably, a plurality of the clamp elements 26 are inflatable to clamp the flexible elongate element 18, and here all the clamp elements 26 are inflatable to clamp the flexible elongate element 18. The clamp elements 26 may therefore be considered to be inflatable elements or inflation devices, for example being bladders which may be expanded by being filled with a fluid. The clamping surface 28 of the or each clamp element 26 preferably forms the outer wall of the bladder or inflation device. The clamp elements may be formed from an elastomer, such as rubber. Additionally or alternatively, preferably a plurality of the clamping surfaces 28 of the clamp elements 26 are flexible, and here all the clamping surfaces 28 are pliant, pliable or flexible. However, it will be appreciated that only one clamp element 26 may be inflatable, for example inflatably clamping the flexible elongate element 18 against a non-inflated or already inflated clamping surface 28. Alternatively, one or more of the clamping surfaces may be rigid.

The clamp elements 26 are elongate, having a longitudinal direction extending in a direction parallel or substantially parallel with the flexible-elongate-element path 16. Each clamp element 26 is preferably cylindrical in shape or has an annular cross-section, although other shapes may be considered. Each clamp element 26 has a supporting element 48 for holding the clamp element 26 in position, the supporting element 48 may extend through the clamp element 26, for example in the instance of an annular clamp element 26, and/or may clamp 12 the clamp element 26 at each or either end. The clamp element 26 includes an inlet for the insertion of a fluid for inflating the clamp element 26. Said inlet may be at or adjacent to an axial end of the clamp element 26, or may for example at an inside surface of the clamp element 26 between the supporting element 48 and the clamp element 26, particularly in the instance that the supporting element 48 extends through the clamp element 26. Said inlet may include a valve for controlling ingress and egress of fluid via the inlet. The clamp element 26 may include a separate outlet for removal of fluid for deflating the clamp element 26, although it will be appreciated that removal of fluid may occur via the inlet. Thus, the inlet may be a combined inlet and outlet.

It will be appreciated that an intervening flexible wall or matrix may be between the clamp elements 26 and the flexible elongate element 18, and as such the clamp elements 26 may not directly engage the flexible elongate element 18.

The clamp 12 may additionally include a conduit for provision of an inflation fluid to the inflation device. The conduit preferably has a conduit-inlet. Due to there being multiple clamp elements 26, there may be a plurality of conduits which preferably have a common conduit-inlet. The clamp assembly 10 may further comprise a pump for pumping inflation fluid to and/or away from the clamp elements 26. Here the pump may, for example, be separate to the remainder of the assembly, for example being on a remotely operated underwater 20 vehicle (ROV). A pump-inlet may be communicatively connected to the pump, the pump-inlet for receiving water 20 surrounding the clamp 12, such as sea-water 20, to be pumped to inflate the clamp elements 26. The inlet may be at or adjacent to the pump. Therefore, the clamp elements 26 are configured to be inflated and deflated via water 20 surrounding the clamp 12. However, it will be appreciated that other inflation fluids or mediums may be considered, such as air, for example pumped via an umbilical to the surface. Oil may be considered as an inflation fluid in some circumstances, although it will be appreciated that it may be preferable that the inflation fluid does not comprise of oil.

The pump, for example a pump outlet of the pump, may be communicatively connectable to the conduit inlet. In the instance of ROV-based pump, the conduit-inlet may be positioned in an easily accessible position, for example on a control panel positioned at or adjacent to a rear of the support 24 relative to the clamp 12.

The clamp assembly 10 preferably further comprises at least one guide for guiding the flexible elongate element 18 onto the flexible-elongate-element path 16 for clamping by the clamp 12. Here there is only a primary guide device 50, although secondary and tertiary guide devices may be considered as well as or instead of the primary guide device.

The primary guide device 50 comprises at least one pair of primary guide arms 50a which project at different angles to each other. Each primary guide arm 50a of a pair preferably projects from the support 24, for example in an in-use horizontal plane, at or adjacent to a common point. In this way, the primary guide device 50 is V-shaped or substantially V5 shaped. The primary guide device 50 is preferably fixed or non-moving relative to the remainder of the support 24 and so may be a passive guide device. The primary guide device 50 may otherwise be referred to as a bumper. Here there are two pairs of primary guide arms 50a one at or adjacent to each axial end of the support 24, although it will be appreciated that only one pair of primary guide arms 50a may be included or more than 10 two pairs.

A secondary guide device may also be considered and is preferably axially offset from the primary guide device, for example the secondary guide device may be proximal to an end of the support as compared to the primary guide device. However, it will be appreciated that the secondary guide device may be distal to the end of the support. The secondary guide device preferably comprises a pair of secondary guide arms. Each pair of secondary guide arms project radially from the support, for example in a radial plane of the flexible-elongate-element path, from spaced apart positions in the horizontal or radial plane of the flexible elongate. The secondary guide arms are moveable or rotatable between an open condition, wherein each secondary guide arm of a pair is directed away from each other, and a closed condition, wherein each secondary guide arm of a pair is directed towards each other and/or overlaps or overlies. To allow for overlapping or overlying, the guide arms preferably project from offset positions in an axial direction. There are here two pairs of secondary guide arms, one at or adjacent to each axial end of the support, although it will be appreciated that only one pair of primary guide arms may be included or more than two pairs. The secondary guide arms may be moved via actuators, for example motors or pistons.

A tertiary guide device may also be considered and is preferably similar to the primary guide device, in that tertiary guide arms of the tertiary guide device are fixed relative to the support. However, the tertiary guide arms may be curvate forming a U-shape or substantial U-shape. The tertiary guide arms have a shorter projecting extent than the primary guide device and are positioned between the ends of the support. The tertiary guide arms may correspond or substantially correspond in shape, size and position to the cross-section of the void for receiving the flexible elongate element.

The clamp assembly 10 or clamp 12 preferably includes a suspension means for suspending, or suspendably supporting, the clamp assembly 10 or clamp 12 from the vessel 14. The suspension means may include a suspension element, not shown, for example a flexible elongate member such as a cable, supportively connectable to the vessel 14. The suspension means may also comprise connection elements for connection of the suspension means to the clamp assembly 10 or clamp 12. For example, the support 24 may have at least one primary aperture for passing a cable or shackle therethrough for connecting the suspension element to the support. The primary apertures may be referred to as eyes and may extend through a projecting plate or wing on the support. The support may additionally comprise secondary apertures which have a smaller radius than the primary apertures. The secondary apertures may be for connecting buoyancy aids, handling cables or other support means which may be able to support the clamp in the water, but not wholly support the weight of the flexible elongate element being clamped.

In use, the vessel 14, which is laying a flexible elongate element 18, may be required to halt the laying process. Therefore, the clamp 12 and support 24 are overboarded into the water 20, if not already prepositioned in the water 20. The clamp assembly 10 is supported from the vessel 14 via the suspension element connected to the vessel 14, for example to the overboarding chute 22 or a crane, and the connection elements on the support 24. The clamp assembly 10 is positioned so as to have a longitudinal extent of the clamp assembly 10 aligned or substantially aligned with the vertical direction. This may be achieved via using buoyancy elements and/or handling cables. The clamp assembly 10 is then manoeuvred at or adjacent to the flexible elongate element 18 which descends through the water 20. The manoeuvring is preferably achieved via the use of a ROV, and so the ROV is engageable and may be connectable with the clamp assembly 10. For example, the control panel may include handles for engagement by arms of the ROV. Alternatively, the clamp assembly 10 may be manoeuvred via the handling cables or the clamp assembly 10 may have a self-propulsion means such as jets or propellers.

The clamp assembly 10 is then manoeuvred so that the flexible elongate element 18 is received along the flexible-elongate-element path 16 for clamping. The guide device 50may be utilised to assist this process. The clamp assembly 10 is manoeuvred so that the flexible elongate element 18 engages one of the primary guide arms 50a. The secondary guide device, if present, which is initially in the open condition, is then actuated to the closed condition so as to positively engage the flexible elongate element 18. This causes relative movement between the flexible elongate element 18 and the clamp assembly 10 so that the flexible elongate element 18 is received at the intersection of the primary guide arms 50a and/or in the tertiary guide device. The relative movement may be achieved by the secondary guide device propelling the remainder of the clamp assembly 10 into position around the flexible elongate element 18, by moving the flexible elongate element 18 itself, or a combination of these two movements.

With the flexible elongate element 18 correctly positioned, the or each clamp 12 or clamp housing 30, which was initially in the open condition, can then be actuated to the closed condition. However, it will be appreciated that the clamp-housing members 32 may close at the same time as the secondary guide device is actuated to the closed condition, and they may, for example be linked. With the clamp housing 30 in the closed condition, the flexible elongate element 18 is not yet clamped. In the instance of multiple clamps 12, the clamps 12 can either be closed sequentially or simultaneously. The clamp-housing members 32 are then locked together by the locking element 44.

The clamp elements 26 can then be inflated or expanded so as to clamp the flexible elongate element 18. To inflate the clamp elements 26, the ROV is connected so that a pump outlet is communicative and sealed with the conduit inlet of the clamp assembly 10. The pump is then activated which pumps sea water 20 from the surroundings of the clamp assembly 10 through the conduits and into the clamp elements 26. This inflates the clamp elements 26 so that the clamping surface 28 of each is brought into engagement with the flexible elongate element 18. This applies a clamping force between the clamp elements 26 to the flexible elongate element 18. The clamp elements 26 of a clamp 12 may be inflated simultaneously or sequentially. The clamp elements 26 of different clamps 12 of the clamp assembly 10 may similarly be inflated simultaneously, for example if there is a common conduit inlet, or separately or sequentially, if there are different conduit inlets. The pump may continuously operate to keep the clamp elements 26 inflated, or the clamp elements 26 may be sealed via a valve.

The clamping condition of the clamp elements 26 can be seen in Figure 4, and may be contrasted to the non-clamping condition shown in Figure 3. As can be seen, in the 30 clamping condition the clamping surface 28 extends towards the flexible-elongateelement path 16 relative to the non-clamping condition.

With the flexible elongate element 18 clamped by the clamp 12 and the clamp assembly 10 supported by the vessel 14, the weight or tension of the flexible elongate element 18 is taken via the clamp 12. On board tensioners can therefore be deactivated or taken off-line.

To unclamp 12 the flexible elongate element 18, for example if laying is able to continue, the clamp elements 26 are deflated. This may be achieved by removing the pump and/or 5 opening a valve. Alternatively, the clamp elements 26 could be evacuated of fluid by the pump, if the pump is a reversable pump, to provide more rapid deflation. The clamp-housing members 32 can then be unlocked, the clamp housing 30 opened and the clamp assembly 10 manoeuvred away. The flexible elongate element 18 can then be continued to be laid. However, it will be appreciated that laying could occur with the flexible elongate 10 element 18 extending through the clamp housing 30 but with the clamp 12 in the non-clamping condition.

The actuators of the clamp-housing members 32 and the secondary guide device 52 may be powered by a power source located on the clamp assembly 10, such as a battery, or alternatively may be powered from a power source on the vessel 14. Such a power source may be connected via an umbilical and/or via an umbilical of the ROV, which could electrically connect with the clamp assembly 10.

Referring to Figures 5 and 6 there is shown two first embodiments of a clamp assembly 10 each having a single clamp 12. Guide devices are omitted from the second embodiments, although these may be used. Each of the clamp assemblies 10 are 20 supported from the vessel 14 via a suspension element, not shown.

Two vessel-suspended clamp assemblies 10 can be used in a method to raise a flexible elongate element 18 without requiring a conventional on-deck tensioner, although a small on-deck tensioner or wheel-based guide may be used to assist with manoeuvring the flexible elongate element once raised by the clamp assemblies 10. This may be achieved via clamping the flexible elongate element 18 with a first clamp assembly 10a, as shown in Figure 5. The first clamp assembly 10a is then raised via the suspension element so as to raise the flexible elongate element 18, as shown in Figure 6. The second clamp assembly 10b preferably then clamps the flexible elongate element 18 so as to support it, and the first clamp assembly 10a may release the flexible elongate element 18. The first clamp assembly 10a can then be lowered, for example to its initial position as shown in Figure 5, to clamp the flexible elongate element 18 again. With the first clamp assembly 10a supporting the flexible elongate element 18, the second clamp assembly 10b releases the flexible elongate element 18. The first clamp assembly 10a is then raised to raise the flexible elongate element 18, as shown in Figure 6. Such steps are then repeated until a desired length of flexible elongate element 18 is raised. Such a method may be described as a "hand-to-hand" method.

By using such a method as illustrated and described, the clamp housings 30 of each clamp assembly 10 are not required to be opened and closed. Additionally, only one clamp assembly 10 is required to be manoeuvred in a vertical direction, and neither are required to be laterally manoeuvred. However, it will be appreciated that the second clamp assembly 10b may be positioned at a raised position whilst the first clamp assembly 10a raises the flexible elongate element 18 towards the second clamp assembly 10b. The first clamp assembly 10a may then hold the flexible elongate element 18 whilst the second clamp assembly 10b is manoeuvred to a lowered position, passing by the first clamp assembly 10a. The second clamp assembly 10b then clamps 12 the flexible elongate element 18, the first clamp assembly 10a releases the flexible elongate element 18, and the second clamp assembly 10b raises the flexible elongate element 18 towards the first clamp assembly 10a.

Additionally, it will be appreciated that two vessel-suspended clamp assemblies 10 as described may not be necessary, and only one vessel-suspended clamp assembly 10 may be used. In such an arrangement, an on-deck clamp or tensioner may be used to tension or support the flexible elongate element 18 whilst the vessel-suspended clamp assembly 10 is being repositioned between raising actions.

One or more vessel-suspended clamp assemblies 10 may also be utilised to raise a damaged section of cable from the seabed. For example, the clamp assembly may be lowered to the seabed and horizontally aligned to receive the flexible elongate element. The flexible elongate element may then be clamped by the clamp assembly and the clamp assembly raised to the vessel.

Referring to Figures 7 and 8, there is shown a second embodiment of a clamp assembly 110. The second embodiment is supported on the deck 14a of a vessel 14. Similar or identical reference numerals are used as for the first embodiment, with 100 added.

The support 124 of the fourth embodiment includes a flexible-elongate-element support 30 surface 170 for supporting the flexible elongate element 18 thereon. The support surface 170 may include rotatable elements such as rollers to allow for the flexible elongate element 18 to move relative to the clamp assembly 110 during laying. The support surface 170 and the clamp elements 126 are positioned so that the clamp elements 126 may close about the flexible elongate element 18 when the flexible elongate element 18 is received on the support surface 170.

It will be appreciated that when used on deck 14a, the clamp assembly 110 may include 5 a supply or reservoir of inflation fluid or medium. The pump may pump the inflation fluid from the reservoir to the clamp elements 126 to inflate the clamp elements 126. The reservoir of inflation fluid may include oil, water, in particular seawater, or other fluids. Alternatively, the clamp elements 126 may be inflated with air, and so the pump may be an air-pump. Additionally, in the instance of seawater 20 as the inflation fluid, it will be 10 appreciated that a reservoir may not be required and seawater 20 may be pumped via the pump of the assembly from the sea directly.

The clamp housing 130 may close about the flexible elongate element 18 and the clamp element 126 clamps the flexible elongate element 18 in the same way as described for the previous embodiments.

Referring to Figures 9 and 10, three first embodiments of the clamp assembly 10a, 10b, 10c may be used to raise flexible elongate element 18 onto a vessel 14 in a similar arrangement to that shown in Figures Sand 6. A bight of loop of flexible elongate element may be raised onto a vessel in a conventional manner, or via a clamp assembly, with two legs 18a, 18b of the bight extending from the vessel 14 into the water. The bight may extend around a quadrant on deck to achieve this arrangement. A first and second clamp assembly 10a, 10b may be supported from the vessel 14 and positioned at or adjacent to a first leg 18a of the bight. A third clamp assembly 10c is supported from the vessel 14 positioned at or adjacent to a second leg 18b of the bight. The third clamp assembly 10c clamps and supports the second leg 18b of the bight whilst the first and second clamp assemblies 10a, 10b raise the flexible elongate element 18 at the first leg 18a of the bight in a similar or identical manner as described for Figures Sand 6. Given that the third clamp assembly 10c is holding the second leg 18b of the bight in position, the amount of flexible elongate element 18 on deck increases. A tensioner may be used to direct onto the deck flexible elongate element 18 which has been raised by this method, and or remove slack from the flexible elongate element 18.

Additionally, a fourth clamp assembly may also be used on the second leg of the bight. This allows for flexible elongate element to be raised to the deck in a similar or identical way as previously described, preferably for both legs of the bight simultaneously. Each leg of the bight should be clamped by at least one clamping assembly at all times to avoid flexible elongate element from descending under gravity.

Alternatively, the clamp assembly may be utilised to lower a bight or half loop of flexible elongate element from a vessel. For example, a bight of flexile elongate element which 5 is on a deck of a vessel, for example having undergone repair, has two legs of flexible elongate element which extend into the water. To overboard the bight, it is usually required to support the bight on an overboarding quadrant which is then raised and lowered via a crane. The overboarding quadrant ensures a curvature of the bight does not have a bend radius which is lower than a minimum bend radius of the flexible 10 elongate element. By supporting the bight at each leg, the tension is reduced on the quadrant and the minimum bend radius of the flexible elongate element is maintained as the flexible elongate element is descended to the seabed.

Whilst described as expanding via inflation, it will be appreciated that in some instances the clamp elements may be expanded via actuators moving portions of the clamp 15 element away from each other.

Referring to Figures 11 and 12, there is shown a representation of a second embodiment of a flexible-elongate-element clamp 212. Here the clamp elements 226 are not necessarily inflatable and may be actuated towards and away from the flexible elongate element 18 so as to clamp the flexible elongate element 18 therebetween. As such the clamp elements may not necessarily be expandable in this instance.

It is therefore possible to provide a flexible elongate element clamp which applies a lower clamping pressure on the flexible elongate element than known clamps, but still maintains a sufficient holding force. Such an arrangement is achieved via utilising a flexible clamping surface, which can help disperse a clamping pressure, and inflatable clamp elements, which in general provide a lower clamping pressure than grips. This prevents or limits damage to a flexible elongate element. The clamp is suitable for use subsea, and therefore deck space can be saved by suspending the clamp from the vessel when in use.

The words 'comprises/comprising' and the words 'having/including' when used herein 30 with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 4. 5.
A flexible-elongate-element clamp for holding a flexible-elongate element when overboarding or onboarding the flexible-elongate element from or to a vessel, the clamp comprising: at least two clamp elements for clamping the flexible elongate element therebetween, each clamp element having a clamping surface and at least one of the clamping surfaces being flexible; at least one of the clamp elements being expandable from a non-clamping condition to a clamping condition so that in use the flexible elongate element is clamped between the clamping surfaces.
A flexible-elongate-element clamp as claimed in claim 1, further comprising a clamp housing including two clamp-housing members, each clamp-housing member for receiving at least one clamp element.
A flexible-elongate-element clamp as claimed in claim 1 or claim 2, wherein at least two of the clamp elements are separable from each other to define a flexibleelongate-element-receiving opening for laterally receiving the flexible elongate element between the clamping surfaces.
A flexible-elongate-element clamp as claimed in claim 3, wherein at least one of the clamp elements is pivotal relative to the other at at least one hinge axis.
A flexible-elongate-element clamp as claimed in claim 4, wherein the clamp elements are pivotal at separate hinge axes.
A flexible-elongate-element clamp as claimed in any one of claims 3 to 5, further comprising at least one guide for directing the flexible elongate element or the clamp so that the flexible elongate element is received through the flexible-elongate-element-receiving opening.
A flexible-elongate-element clamp as claimed in claim 6, wherein the or each guide is moveable for engaging the flexible elongate element and creating relative movement between the flexible elongate element and the clamp to receive the flexible-elongate-element-receiving in a clamping position 8. A flexible-elongate-element clamp as claimed in claim 6 or claim 7, wherein there are two guides.
9. A flexible-elongate-element clamp as claimed in claim 8, wherein the guides are offset from each other.
10. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein a plurality of the clamp elements is expandable from a non-clamping condition to a clamping condition
11. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein a plurality of the clamping surfaces is flexible.
12. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein the number of clamp elements is greater than or equal to three.
13. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein the number of clamp elements is greater than or equal to six.
14. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein the clamp is elongate along a direction of the clamping surface.
15. A flexible-elongate-element clamp as claimed in claim 14, wherein a longitudinal extent of the clamp is greater than or equal to 2 metres.
16. A flexible-elongate-element clamp as claimed any one of the preceding claims, wherein said at least one clamp element is inflatable from the non-clamping condition to the clamping condition.
17. A flexible-elongate-element clamp as claimed in claim 16, further comprising a pump for pumping fluid surrounding the clamp to inflate said at least one clamp element.
18. A flexible-elongate-element clamp as claimed in any one of the preceding claims, further comprising a suspension means for suspending the clamp housing from the vessel.
19. A flexible-elongate-element clamp as claimed in any one of the preceding claims, wherein the suspension means comprises a flexible elongate member.
20. A flexible-elongate-element-clamp assembly comprising: at least one flexible-elongate-element clamp as claimed in anyone of the preceding claims; and a support for supporting and receiving the or each clamp.
21. A flexible-elongate-element-clamp assembly as claimed in claim 20, further comprising a plurality of clamps supportable and receivable by the support along the flexible-elongate-element path.
22. A flexible-elongate-element-clamp assembly as claimed in claim 20 or claim 21, wherein the support has a U-shaped or substantially U-shaped cross-section which defines a channel for receiving the or each clamp therein.
23. A flexible-elongate-element-clamp system comprising: a power or signal transmission cable; and a flexible-elongate-element clamp as claimed in any one of claims 1 to 19, the clamp arranged to clamp the power or signal transmission cable.
24. A method of reducing deck space required for holding a flexible elongate element relative to a vessel, the method comprising; a) suspending a flexible-elongate-element clamp as claimed in any one of claims 1 to 19 from the vessel; b) receiving a flexible elongate element between the clamping surfaces of said clamp; c) expanding at least one of the clamp elements from a non-clamping condition to a clamping condition to hold the flexible elongate element between the clamping surfaces.
25. A method of raising or lowering a flexible elongate element along a flexibleelongate-element path without requiring the use of a flexible-elongate-element tensioner, the method comprising: a) providing a first and second flexible-elongate-element clamp as claimed in any one of claims 1 to 19, each suspended from the same or separate vessels; b) clamping the flexible elongate element with a first clamp and raising the flexible elongate element by raising the first clamp to a higher position along the flexible-elongate-element path; c) clamping the flexible elongate element with the second clamp to hold the flexible elongate element; and d) unclamping the first clamp. 10