WO2020249732A1

WO2020249732A1 - Clamping system

Info

Publication number: WO2020249732A1
Application number: PCT/EP2020/066309
Authority: WO
Inventors: Kristen Andrew FOSHAUG; Aleksander HAGEN; Pål Magne HISDAL
Original assignee: Connector Subsea Solutions As
Priority date: 2019-06-14
Filing date: 2020-06-12
Publication date: 2020-12-17
Also published as: GB2584729A; GB2584729B; GB201908581D0

Abstract

A clamping system for a pipe, the clamping system comprising a first clamp shell, a second clamp shell, and a pre-tensioning device comprising a first elongate member comprising a first wedge shaped portion and a second elongate member comprising a second wedge shaped portion, wherein the first wedge shaped portion and the second wedge shaped portion are arranged in slidable contact with each other, and wherein, in use, relative movement of the first elongate member and the second elongate member along their longitudinal axes causes a pretension force to be applied between the first clamp shell and the second clamp shell.

Description

CLAMPING SYSTEM

Field of the Invention The present invention relates to a clamping system for a pipe and a method of clamping a pipe, in particular a subsea pipe.

Background Subsea pipes, such as pipelines and risers, are commonly used in the oil and gas industries to transport substances underwater. If these pipes become damaged, they are typically repaired using clamps, which fit around the damaged part of the pipe, and may provide structural support and sealing to the pipe. Such clamps are typically secured to the pipes using bolts, which are put under tension (known as pre-tension) in order to provide a secure fit to the pipe.

There is a general need to provide an improved clamp for a subsea pipe.

Summary of the Invention

According to a first aspect of the present invention, there is provided a clamping system for a pipe, the clamping system comprising: a first clamp shell; a second clamp shell; and a pre-tensioning device comprising: a first elongate member comprising a first wedge shaped portion; and a second elongate member comprising a second wedge shaped portion; wherein the first wedge shaped portion and the second wedge shaped portion are arranged in slidable contact with each other; and wherein, in use, relative movement of the first elongate member and the second elongate member along their longitudinal axes causes a pretension force to be applied between the first clamp shell and the second clamp shell.

Preferably, the first elongate member comprises a first plurality of wedge shaped portions arranged along a longitudinal axis of the first elongate member; the second elongate member comprises a second plurality of wedge shaped portions arranged along a longitudinal axis of the second elongate member; and the first plurality of wedge shaped portions and the second plurality of wedge shaped portions are arranged in slidable contact with each other.

Preferably, the first plurality of wedge shaped portions and the second plurality of wedge shaped portions each form a sawtooth shape.

Preferably, the first and second elongate members are separately formed from the first and second clamp shells; and the first and second elongate members are mounted on the first clamp shell.

Preferably, the system further comprises a plurality of fasteners extending between the first clamp shell and the second clamp shell to join the first clamp shell to the second clamp shell; wherein said pretension force between the first clamp shell and the second clamp shell is provided by the relative sliding of the first plurality of wedge shaped portions and second plurality of wedge shaped portions to create pre-tension in the fasteners.

Preferably, a first end of each of the plurality of fasteners is fixedly secured to the second elongate member.

Preferably, a second end of each of the plurality of fasteners is removably secured to the second clamp shell by a nut.

Preferably, each of the plurality of fasteners comprises a thread around at least part of its circumference at the second end, and each respective nut comprises a thread around at least part of its inner circumference.

Preferably, the system further comprises an elongate nut actuating device comprising a plurality of nut actuating teeth; wherein: each nut comprises a plurality of teeth on its outer circumferential surface; and the nut actuating device is arranged to slide such that the nut actuating teeth interact with the teeth on the outer circumferential surfaces of the nuts to rotate each of the nuts simultaneously.

Preferably, each nut comprises two separable parts, wherein the second end of each of the fasteners is released when the separable parts are separated, and the second end of each of the fasteners is secured to the second clamp shell when the separable parts are brought together.

Preferably, the system further comprises at least one locking rod, wherein a second end of each of the plurality of fasteners comprises an aperture configured to receive the locking rod such that the fasteners are removably secured to the second clamp shell.

Preferably, the first elongate member comprises a first section and a second section, wherein the first section and the second section are arranged to move away from each other to thereby slide the first plurality of wedge shaped portions relative to the second plurality of wedge shaped portions.

Preferably, the system further comprises an outer sleeve arranged to be mounted to span at least part of the first clamp shell and the second clamp shell to join the first clamp shell to the second clamp shell, wherein the first elongate member is located on the first clamp shell; and the second elongate member is located on the outer sleeve.

Preferably, the second clamp shell comprises a third plurality of wedge shaped portions; the first outer sleeve comprises a fourth plurality of wedge shaped portions; and the third plurality of wedge shaped portions and the fourth plurality of wedge shaped portions are configured to slide relative to each other to thereby secure the first clamp shell to the second clamp shell.

Preferably, the outer sleeve is divided into a first block and a second block, wherein the first block and the second block are configured to move towards each other to thereby slide the wedge shaped portions relative to each other. Preferably, the system further comprises a second pre-tensioning device.

Preferably, the system further comprises at least one seal located on the inner circumference of the first and second clamp shells.

Preferably, the clamping system is arranged to be assembled by a remote operated vehicle.

Preferably, the clamp is for repairing a surface pipeline, a subsea pipeline and/or subsea riser.

According to a second aspect of the present invention, there is provided a method of clamping a subsea pipe using a clamping system, the method comprising: arranging a first clamp shell and a second clamp shell around the pipe; providing a pre-tensioning device comprising a first elongate member comprising a first wedge shaped portion, and a second elongate member comprising a second wedge shaped portion, wherein the first wedge shaped portion and the second wedge shaped portion are in slidable contact with each other; and applying a pretension force between the first clamp shell and the second clamp shell by moving the first elongate member and the second elongate member relative to each other along their longitudinal axes.

Preferably, the method is performed in a system according to any one the above aspects.

Description of the Drawings

The present invention will now be described, by way of non-limitative example only, with reference to the following figures, in which:

Figure 1 is an exploded perspective view of a clamping system according to an embodiment of the present invention; Figure 2 is an exploded view of the clamping system according to an embodiment of the present invention viewed axially along the pipe;

Figure 3 is a perspective view of the assembled clamping system according to an embodiment of the present invention;

Figure 4 is a view of the assembled clamping system according to an embodiment of the present invention viewed axially along the pipe; Figure 5 is a close up view of the wedges according to an embodiment of the present invention before pre-tensioning;

Figure 6 is a close up view of the wedges according to an embodiment of the present invention after pre-tensioning;

Figure 7 is a close up view of the nut actuating member according to an embodiment of the present invention before actuation;

Figure 8 is a close up view of the nut actuating member according to an embodiment of the present invention after actuation;

Figure 9 is a perspective view of a clamp shell according to an embodiment of the present invention; Figure 10 is a perspective view of an outer sleeve according to an embodiment of the present invention.

Figure 11 is a perspective view of a clamping system according to an embodiment of the present invention, including fasteners with apertures, and locking rods;

Figure 12 is a close up view of an arrangement with a plurality of split nuts, with the split nuts in a released configuration; and Figure 13 is a close up view of an arrangement with a plurality of split nuts, with the split nuts in a secured configuration.

Detailed Description

The present invention provides a clamping system for a subsea pipe. An example of such a clamping system is shown in Figures 1 to 8. The clamping system 100 is arranged to clamp a pipe 110. The pipe typically has a substantially cylindrical shape, and thus has a circular cross section.

The clamping system includes a first clamp shell 101 and a second clamp shell 102. The first clamp shell 101 and second clamp shell 102 fit together to surround the pipe 110 so that they can be clamped to the pipe. When positioned around the pipe 110, the interior shape of the first and second clamp shells may be substantially cylindrical such that they loosely surround the pipe before the clamp is secured (i.e. before the clamp grips the pipe). In other words, the first clamp shell and second clamp shell fit loosely around the pipe so that they can slide along the pipe.

The clamping system further comprises a pre-tensioning device 103. The pre tensioning device 103 may cause a force to be applied between the first clamp shell 101 and the second clamp shell 102, in order to firmly secure the first clamp shell 101 and second clamp shell 102 together. Thus, even if unexpected external forces are applied to the clamp shells, or forces are applied to the clamp shell by the pipe 110, the first clamp shell 101 and second clamp shell 102 remain secured in place because they cannot be separated unless the pre-tensioning force is overcome.

The pre-tensioning device 103 may comprise a first elongate member 104 comprising a first plurality of wedge shaped portions 106 (or wedges), and a second elongate member 105 comprising a second plurality of wedge shaped portions 107 (or wedges). The pluralities of wedge shaped portions 106, 107, may each form a generally sawtooth shape on a surface of the first and second elongate members, although their shape is not limited thereto. That is, each of the wedge shaped portions may have an inclined surface which is inclined with respect to the direction in which the elongate members are elongate (i.e. the longitudinal axis of the elongate member), and a surface which is perpendicular to the longitudinal direction, such that each wedge shaped portion has a triangular shape in cross-section.

As shown in Figure 1, the first elongate member 104 may have a generally elongate cuboidal shape, with the plurality of wedge shaped portions 105 forming a sawtooth shape on one edge of the cuboidal shape. Likewise, the second elongate member 105 may form a cuboidal shape, with the plurality of wedge shaped portions 107 forming a sawtooth shape on one face of the cuboid.

In the pre-tensioning device 103, the first plurality of wedge shaped portions 105 are in contact with the second plurality of wedge shaped portions 107, and the wedge shaped portions can slide relative to each other when the first elongate member 104 and second elongate member 106 are moved relative to each other (in the longitudinal direction). When the wedges slide relative to each other, one of the pluralities of wedge shape portions may be fixed, such that the movement of the other plurality of wedge shaped portions (i.e. the relative movement) causes the wedges to slide along each other. The relative movement of the inclined surfaces causes a gap G to be created between the wedges, as shown in Figures 5 and 6. Because of the inclined surfaces, the relative movement of the first elongate member 104 and second elongate member 106 has a component in the longitudinal direction and a component which is perpendicular to the longitudinal direction.

When the first clamp shell 101 is joined to the second clamp shell 102, and the first and second elongate members slide relative to each other when attached to the clamp shells, the component of the sliding movement which is perpendicular to the longitudinal direction causes a pre-tensioning force to be applied between the first clamp shell 101 and the second clamp shell 102. In the arrangement described above and shown in Figure 1, a plurality of wedge shaped portions is present on both the first elongate member 104 and on the second elongate member 106. However, it will be appreciated that a single wedge shaped portion on each of the first and second elongate members could be used.

In the arrangement shown in Figure 1, the first elongate member 104 and the second elongate member 105, which form part of the pre-tensioning device 103, are formed as separate parts to the clamp shells, and are mounted on the first clamp shell 101. In other arrangements, the first and/or elongate members may also be integrally formed with the clamp shells. For example, the wedge shaped portions may be machined into the clamp shell.

As shown in Figures 1-4, the first clamp shell 101 maybe secured to the second clamp shell 102 by a plurality of fasteners 108. The fasteners 108 may be elongate fasteners such as bolts or screws, or any other suitable fasteners. The first and second elongate members may be arranged such that, when they slide relative to each other, a pre tension force is applied to the fasteners, which is in turn applied between the first clamp shell 101 and the second clamp shell 102.

In order to apply the pre-tension force to the fasteners 108, one end of the fasteners 108 may be fixedly secured to the second elongate member 105, as shown in, for example Figure 1. The other end of the fasteners 108 may be secured to the second clamp shell 102. The second end may be removably secured, so that, the fasteners 108 are attached only to the second elongate member (and thus the pre-tensioning device 103 and the first clamp shell 101) before the clamp is assembled, as shown in the exploded view of Figure 1.

Then, when the clamp is assembled around the pipe, the second end of each of the fasteners 108 can be secured to the second clamp shell 102, as shown in, for example, Figures 3 and 4. The second end may be removably secured by, for example, a nut.

In the arrangement shown in Figures 1-4, each of the fasteners 108 is a partially threaded bolt with a thread at one end around part of its circumference. In other words, the thread only extends around a portion of the circumference of the bolt at the tip of the bolt. A plurality of corresponding partially threaded nuts 109 may be used to secure the partially threaded bolts, with each of the plurality of particularly threaded nuts 109 having a thread around part of its inner circumference. This may allow the thread on the nuts 109 to cooperate with the thread on the bolt 108 to thereby secure the end of the bolt. The provision of a thread around only part of the circumference of the bolts allows the bolts to be inserted into the nuts without the bolts being rotated, and allows the rotation of the bolts to be carried out in a subsequent operation after the bolts have been inserted into the nuts. In addition, the nuts being partially threaded may prevent over- tightening of the bolts.

As shown in Figures 1-4, the clamping assembly may further be provided with an elongate nut actuating device 114. As shown in Figures 7 and 8, the elongate nut actuating member is generally rectangular in shape, and includes a plurality of teeth protruding from one of its surfaces. The teeth form grooves which are perpendicular to the direction in which the nut actuating device 114 is elongate.

Each of the partially threaded nuts 109 may have corresponding teeth around part of its outer circumference, the teeth forming grooves which extend generally in the axial direction of the nut. As shown in Figures 7 and 8, the nuts 109 and the nut actuating device 114 may be mounted on the second clamp shell 102 such that the grooves on the nut actuating device 114 and the grooves on the outer circumference of the nuts 109 are in contact with each other. Figure 7 shows the device when the bolts 108 are not secured in position by the nuts 109.

In order to secure the bolts in position, the nut actuating device is moved in the direction in which it is elongate (i.e. along its longitudinal axis). This causes the teeth on the nut actuating device to cooperate with the teeth on the external circumference of the nuts, and cause the nuts to rotate. This may secure each of the bolts 108 to the second clamp shell 102. Figure 8 shows the position of the nuts after this has been done. Once this has been done, both ends of the bolts 108 are secured, which then allows the bolts to be pre-tensioned by the pre-tensioning device 103. Such an arrangement may allow all of the nuts 108 to be tightened in one operation by moving the nut actuating device, which results in easier installation of the clamp compared to tightening each nut individually. As shown in Figure 1, the first elongate member 104 may be divided into a first section 104a and a second section 104b. The relative motion of the first elongate member and the second elongate member may be provided by moving the first section and second section away from each other in the axial direction. In such an arrangement, there may be no axial movement of the second elongate member (i.e. the relative motion between the first elongate member and the second elongate member is provided by moving the first elongate member only). This may be achieved by an actuating cylinder 115 provided between the first and second sections of the first elongate member, as shown in Figure 1. The actuating cylinder may be actuated by a remotely operated vehicle (ROV), by hydraulics or by any other suitable means known in the art of clamping for subsea and/or surface operations.

In the arrangement in which relative motion of the first elongate member and the second elongate member is provided by moving the first section 104a and second section 104b away from each other in the axial direction, it will be appreciated that the orientations of the wedge shaped portions 106 differ such that inclined surfaces of the wedge shaped portions in the first and second sections of the first elongate member slope in opposite directions. Thus, when these two sections move away from each other, the pre-tensioning force applied to the bolts 108 is in the same direction. Likewise, the orientations of the wedge shaped portions of the second elongate member 105 may be different in the two corresponding parts of the second elongate member 105, so that they cooperate with the first and second sections of the first elongate member.

As shown in Figures 1-4, a second pre-tensioning device may be provided to join the first clamp shell to the second clamp shell on the opposite side of the clamp shells to the first pre-tensioning device. The second pre-tensioning device may be the same as the first pre-tensioning device, and mounted so that its first elongate member and second elongate member are mounted on the second clamp shell 102. Such an arrangement may provide symmetric pre -tensioning, increase the amount of pre-tensioning that can be applied, and prevent stress concentrations in the clamp or pipe. The clamp shells may have at least one seal 112 on their inner circumferential surface, and, as shown in Figure 1, may have two seals 112 provided around their inner circumferential surface, spaced apart in the axial direction of the pipe. The sealing provided by the seals may be activated by a seal actuator, which applies a force to the seal so that a reaction force is produced against a stationary part of the clamp shell, thus forming the seal. The seals may prevent the content of the pipe from leaking out if a portion of the pipe is damaged.

The first clamp shell 101 and the second clamp shell 102 may also include at least one gripping parts 113, and may, as shown in Figure 1, include two gripping parts 113 located at either axial end of the clamp shells. These gripping parts secure the clamping system to the pipe so that it cannot move relative to the pipe, and may also provide structural support to the pipe near the area where the pipe is damaged. The gripping parts 113 may be actuated using a similar arrangement of sliding wedges as described above in relation to the pre-tension, with the wedges extending circumferentially around the insides of the clamp shells. The gripping parts 113 may be activated after the clamp shells have been arranged around the pipe, and after the pre -tension has been applied.

It will be understood that, although Figure 1 shows an arrangement with two seals and two structural supports, the first clamp shell 101 and the second clamp shell 102 may include any number or combination of seals and/or structural supports. The seals 112 and gripping parts 113 may cooperate to repair, or prevent further damage to, the pipe 110. In one arrangement, a number of separate seals which together form a seal envelope around the pipe may be used. In such an arrangement, there may be a seal running longitudinally along the pipe along the two lines where the first and second clamp shells meet on either side of the pipe, thus providing two longitudinal seals. The longitudinal seals may be activated when the pre-tension is applied. There may also be seals running

circumferentially around the two ends of the clamping system (i.e. at the axial ends of the clamp shells. There may be one such seal at each end of each clamp shell, making a total of four circumferential seals. The longitudinal seals and circumferential seals may co operate to form a single seal envelope. In a second arrangement, as shown in Figures 9 and 10, a similar principle to the first arrangement is used to apply a pre -tension force between the first clamp shell 101 and the second clamp shell 102 is used. However, in this arrangement, the first elongate member 104 is located on the first clamp shell, and the second elongate member is located on a separate outer sleeve 201. In other words, the pre-tensioning device 103 is split between the first clamp shell 201 and the outer sleeve 202.

In such an arrangement, the first plurality of wedge shape portions 206, which form part of the first elongate member 204, are located on the first clamp shell 201, and the second plurality of wedge shape portions 207, which form part of the second elongate member 205, are located on the outer sleeve 202. The outer sleeve 202 is arranged to be mounted to span at least part of the first clamp shell 201 and the second clamp shell 203 to join the first clamp shell 201 to the second clamp shell 203. In other words, the outer sleeve 202 is mounted over part of the first clamp shell 201 and the second clamp shell 203 to join them together. Thus, instead of the pre -tension force being transmitted through bolts 108, as in the first arrangement, the pre -tension force is transmitted through the outer sleeve 202 in the second arrangement.

The second clamp shell 203 may also comprise a third plurality of wedge-shaped portions 208. The outer sleeve 202 may comprise a fourth plurality of wedge shaped portions 209. Thus, the first and second plurality of wedge shape portions may slide relative to each other, and the third and fourth plurality of wedge-shaped portion may slide relative to each other, such that a pre -tensioning force is applied to the first and second clamp shells through the outer sleeve 202 from both sides of the outer sleeve. The second clamp shell 203 may be substantially the same as the first clamp shell 201.

As shown in Figure 10, the outer sleeve 202 may be divided into a first block 210 and a second block 211. The first block and second block may be joined by rods, and the first block 210 and the second block 211 may slide towards each other to move their respective wedge shape portions relative to the wedge shaped portions on the clamp shells. The sliding movement may be provided by the first block 210 and the second block 211 pushing against each other, or against the clamp shells. In other words, the reaction force when the blocks move may be provided by the other blocks, or by the clamp shells.

It will be understood that the inclined surfaces of the first block and the inclined surfaces of the second block may slope in opposite directions such that when they are slid towards each other they all provide a pre-tensioning force in the same direction, and such that the longitudinal components of the force may cancel each other out. This means that there may be no resultant longitudinal force or bending moment applied to the clamp or pipe. However, in some arrangements, there may be a residual longitudinal force, depending on the specific arrangement of wedge shaped portions that is used. It will also be appreciated that, if the direction of incline of the wedge shape portion were reversed, the tension could be applied by moving the first block and second block away from each other, rather than towards each other, in a similar manner to the first arrangement. The reaction force required to sustain the tension may be provided by the two blocks pushing against each other, or against the housing.

It will also be appreciated that a second outer sleeve may be provided on the opposite side of the clamp to the first outer sleeve, which interacts with corresponding wedges provided on the circumferentially opposite side of the clamp shells. Thus, a second pre-tensioning device may be provided, which may be the same as the first pre tensioning device. In both the first and second arrangements, the two clamp shells may be substantially the same as each other. This means that two of the same component can be used for the two clamp shells, rather than manufacturing and providing two different clamp shells.

In the arrangements described above, various configurations of nuts and fasteners, and optionally, nut actuating members, are used to secure the clamp shells together, to allow the pre-tension to be applied. However, it will be understood that other

arrangements may be used to secure the clamp shells together. Examples of such arrangements are described below. It will be understood that in these arrangements, other than the features described below, the other features of the clamping system may be substantially the same as, or similar to, the arrangements described above. Further, the various arrangements for securing the clamp shells together may be combined so as to use more than one of the arrangements described.

In another arrangement for securing the clamp shells together and as shown in Figure 11, each fastener 108 may include an aperture 108a at one end (e.g. the end which is secured to the second clamp shell) as an alternative to a thread onto which a nut is fastened. One or more locking rods 109a may be inserted into the apertures to secure the bolts (and thus the two clamp shells). That is, the locking rod or rods fill the apertures, thus bracing the end of the fastener which has the aperture against the clamp shell.

In one arrangement, the apertures of each bolt may be aligned with each other (and coincident when viewed from the axial direction) so that the locking rod 109a can be inserted through the apertures in the longitudinal direction. It will be understood that, as shown in Figure 11, more than one locking rod 109a may be provided, with each locking rod passing through a subset of the apertures, or in other arrangements that a single locking rod passing through all of the apertures may be provided. It will be understood that, when multiple locking rods are used, the apertures of each bolt need not be aligned, but rather only those which share the same locking rod.

In another arrangement for securing the clamp shells together and as shown in Figures 12 and 13, as an alternative to, or in addition to, the bolts 108 and partially threaded nuts 109 described above, the nuts may be split nuts 308, split circumferentially into two parts 308a, 308b. This is shown in Figures 12 and 13, which are a frontal view of the end of the nuts and bolts (i.e. a frontal partial view of the view of Figure 8, but with a split nut arrangement rather than a partially threaded nut arrangement). Each split nut comprises a first separable part 308a and a second separable part 308b, which separate along a line perpendicular to the axis of the nut.

The end of each of the fastener which is to be secured to the second clamp shell is released when the separable parts of the split nut are separated, and is secured when the separable parts of the split nut are brought together (i.e. by gripping the fastener). Thus, rather than the nut being threaded (or screwed) onto the fastener, it is moved into place with the separable parts separated (i.e. split apart, with the nut in a released configuration), then the separable parts are brought together to secure the nut to the fastener (i.e. the nut is in a secured configuration).

It will be understood that the split nut may be of any suitable shape, such as a round nut (i.e. a split version of the round nuts shown in Figure 8), or have a rectangular shape when closed, as shown in Figures 12 and 13. It will be understood that the two separable parts may be brought together and separated by any suitable actuator 314. Thus, in this arrangement the actuator 314 may fulfil the function of the nut actuating device (i.e.

releasing and securing the nuts to thereby release and secure the clamp shells) described above in relation to arrangements which use partially threaded nuts.

In arrangements which use a split nut, there may be no pitch on the thread such that the threads of the nuts (and corresponding threads on the fasteners) are parallel to each other.

In other words, instead of the thread on the nut being a helical shape, it is made up of a plurality of parallel circles around the circumference of the nut, which do not meet each other. The thread on the bolt is also made up of a plurality of corresponding parallel circles around the circumference of the bolt, which do not meet each other. This means that, instead of the nut being screwed on (i.e. attached by rotating it onto the bolt), the two parts of the nut can be moved apart, moved into position around the bolt, and brought together to secure the nut to the bolt. This may be particularly advantageous in high pressure applications. It will also be understood that in some arrangements, a mixture of split nuts and partially threaded nuts may be used.

According to the present invention, there is also provided a method of clamping a subsea pipe. In such a method, the first clamp shell 102 and the second clamp shell 102 are arranged around the pipe (i.e. positioned either side of the pipe), as shown in Figures 1 and 2. The first clamp shell and the second clamp shell are then moved together to fit either side of the pipe. Where present, the bolts 108 are placed into holes 116 in the second clamp shell. In arrangements where bolts and nuts are present (as described above), the bolts are then secured by inserting the bolts into the nuts and rotating the nuts. Then, a pretension force is applied between the first clamp shell and the second clamp shell by moving the first elongate member and the second elongate member relative to each other along their longitudinal axes. The clamp is then in the closed position, as shown in Figures 3 and 4.

The clamping system of the present invention may be used for a subsea pipe of any size, and installed horizontally, vertically or at any angle therebetween. For example, it may be used to repair a riser, or a subsea or topside pipeline.

Such an assembly process may be assembled by a subsea remote operated vehicle. Such a vehicle may manipulate the various moving parts of the clamping assembly, for example by using a robotic arm or by using a hydraulic attachment.

The embodiments of the present invention provide an improved subsea clamping system to known systems and techniques because pre-tensioning can be applied efficiently and effectively.

The clamping system according to embodiments may be used to both provide structural support to a pipe, by gripping the pipe, and also to provide a seal around the pipe. Embodiments also include the clamping system only providing structural support to a pipe and not a seal around the pipe, as well as the clamping system only providing a seal around a pipe and not structural support to the pipe. Embodiments therefore include clamping systems as described herein with the features for both providing structural support to a pipe as well as forming a seal around the pipe, as well as a clamping system for providing the features required for only one of these functions.

The accompanying drawings are provided for purposes of illustration only, and the dimensions, positions, order, and relative sizes reflected in the drawings attached hereto may vary. The detailed description will be better understood in conjunction with the accompanying drawings, with reference made in detail to embodiments of the present subject matter, examples of which are illustrated in the drawings. Each example is provided by way of explanation of the present subject matter, not limitation of the present subject matter. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope of the present subject matter. Thus, it is intended that the present subject matter covers such modifications and variations as come within the scope of the appended claims and their equivalents.

In the foregoing description, it will be appreciated that the phrases“at least one”, “one or more”, and“and/or”, as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. The term“a” or“an” entity, as used herein, refers to one or more of that entity. As such, the terms“a” (or“an”),“one or more” and “at least one” can be used interchangeably herein. All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise,

counterclockwise, and/or the like) are used for identification purposes to aid the reader’s understanding of the present disclosure, and/or serve to distinguish regions of the associated elements from one another, and do not limit the associated element, particularly as to the position, orientation, or use of this disclosure.

Claims

1. A clamping system for a pipe, the clamping system comprising:

a first clamp shell;

a second clamp shell; and

a pre-tensioning device comprising:

a first elongate member comprising a first wedge shaped portion; and

a second elongate member comprising a second wedge shaped portion;

wherein the first wedge shaped portion and the second wedge shaped portion are arranged in slidable contact with each other; and

wherein, in use, relative movement of the first elongate member and the second elongate member along their longitudinal axes causes a pretension force to be applied between the first clamp shell and the second clamp shell.

2. The clamping system according to claim 1, wherein:

the first elongate member comprises a first plurality of wedge shaped portions arranged along a longitudinal axis of the first elongate member;

the second elongate member comprises a second plurality of wedge shaped portions arranged along a longitudinal axis of the second elongate member; and

the first plurality of wedge shaped portions and the second plurality of wedge shaped portions are arranged in slidable contact with each other.

3. The clamping system according to claim 2, wherein the first plurality of wedge shaped portions and the second plurality of wedge shaped portions each form a sawtooth shape.

4. The clamping system according to claim 1, 2 or 3, wherein the first and second elongate members are separately formed from the first and second clamp shells; and

the first and second elongate members are mounted on the first clamp shell.

5. The clamping system according to claim 2-4, further comprising a plurality of fasteners extending between the first clamp shell and the second clamp shell to join the first clamp shell to the second clamp shell;

wherein said pretension force between the first clamp shell and the second clamp shell is provided by the relative sliding of the first plurality of wedge shaped portions and second plurality of wedge shaped portions to create pre-tension in the fasteners.

6. The clamping system according to claim 5, wherein a first end of each of the plurality of fasteners is fixedly secured to the second elongate member.

7. The clamping system according to claim 6, wherein a second end of each of the plurality of fasteners is removably secured to the second clamp shell by a nut.

8. The clamping system according to claim 7, wherein each of the plurality of fasteners comprises a thread around at least part of its circumference at the second end, and each respective nut comprises a thread around at least part of its inner circumference.

9. The clamping system according to claim 7 or 8, further comprising an elongate nut actuating device comprising a plurality of nut actuating teeth, wherein:

each nut comprises a plurality of teeth on its outer circumferential surface; and the nut actuating device is arranged to slide such that the nut actuating teeth interact with the teeth on the outer circumferential surfaces of the nuts to rotate each of the nuts simultaneously.

10. The clamping system according to claim 7, wherein each nut comprises two separable parts, wherein the second end of each of the fasteners is released when the separable parts are separated, and the second end of each of the fasteners is secured to the second clamp shell when the separable parts are brought together.

11. The clamping system according to claim 6, further comprising at least one locking rod, wherein a second end of each of the plurality of fasteners comprises an aperture configured to receive the locking rod such that the fasteners are removably secured to the second clamp shell.

12. The clamping system according to any preceding claim, wherein the first elongate member comprises a first section and a second section, wherein the first section and the second section are arranged to move away from each other to thereby slide the first plurality of wedge shaped portions relative to the second plurality of wedge shaped portions.

13. The clamping system according to claim 1 or 2, further comprising an outer sleeve arranged to be mounted to span at least part of the first clamp shell and at least part of the second clamp shell to join the first clamp shell to the second clamp shell,

wherein the first elongate member is located on the first clamp shell, and the second elongate member is located on the outer sleeve.

14. The clamping system according to claim 13, wherein:

the second clamp shell comprises a third plurality of wedge shaped portions;

the first outer sleeve comprises a fourth plurality of wedge shaped portions; and the third plurality of wedge shaped portions and the fourth plurality of wedge shaped portions are configured to slide relative to each other to thereby secure the first clamp shell to the second clamp shell.

15. The clamping system according to any claim 13 or 14, wherein the outer sleeve is divided into a first block and a second block, wherein the first block and the second block are configured to move towards each other to thereby slide the wedge shaped portions relative to each other.

16. The clamping system according to any preceding claim, further comprising a second pre-tensioning device.

17. The clamping system according to any preceding claim, further comprising at least one seal located on the inner circumference of the first and second clamp shells.

18. The clamping system according to any preceding claim, wherein the clamping system is arranged to be assembled by a remote operated vehicle.

19. The clamping system according to any preceding claim, wherein the clamp is for repairing a surface pipeline, a subsea pipeline and/or subsea riser.

20. A method of clamping a subsea pipe using a clamping system, the method comprising:

arranging a first clamp shell and a second clamp shell around the pipe;

providing a pre-tensioning device comprising a first elongate member comprising a first wedge shaped portion, and a second elongate member comprising a second wedge shaped portion, wherein the first wedge shaped portion and the second wedge shaped portion are in slidable contact with each other; and

applying a pretension force between the first clamp shell and the second clamp shell by moving the first elongate member and the second elongate member relative to each other along their longitudinal axes.

21. The method according to claim 20, wherein the method is performed in a system according to any one of claims 1-19.