CONDUIT

FIELD OF THE INVENTION AND PRIOR ART

The present invention relates to a system according to the preamble of claim 1 for supporting an end section of a flexible conduit when the conduit is lowered into the sea and installed at the seabed in order to be connected to an end section of another conduit which in advance has been installed at the seabed fixed to a subsea support structure. A system according to the preamble of claim 1 is previously known from WO 2011/043672 A1. This known system comprises a termination head which is permanently fixed to the end section of a first conduit that is to be lowered into the sea from a surface vessel in order to be connected to the end section of a second conduit at the seabed. The system disclosed in WO 2011/043672 A1 comprises a lifting tool for supporting the termination head and the end section of the first conduit when they are lowered into the sea. This lifting tool comprises a lifting frame, which is detachably mounted to the end section of the first conduit. The lifting tool also comprises a lifting yoke, which is pivotally connected to the lifting frame so as to allow the lifting frame to pivot in relation to the lifting yoke when the lifting frame comes into contact with a guiding member at the end section of the second conduit. When the termination head has been properly landed onto a landing unit in front of the end section of the second conduit, the lifting frame is detached from the end section of the first conduit and retrieved to the surface vessel together with the lifting yoke.

SUMMARY OF THE INVENTION The object of the present invention is to achieve a further development of a system of the above-mentioned type so as to provide a system that is improved in at least some aspect.

According to the invention, this object is achieved by a system having the features defined in claim 1.

The system of the present invention comprises a termination head, which is to be permanently fixed to the end section of the conduit, and a lifting yoke, which has an upper end and a lower end, an attachment configured for engagement with a lifting wire being provided on the lifting yoke at the upper end thereof. The lifting yoke is configured to be detachably connected to the termination head through a joint formed between the lower end of the lifting yoke and a rear structural part of the termination head, the termination head being pivotable in relation to the lifting yoke, about a horizontal pivot axis formed by said joint, from a vertical position to a horizontal position.

With the system of the present invention, the lifting yoke is pivotally connected directly to the termination head, in contrast to the prior art solution disclosed in WO 2011/043672 A1 where the lifting yoke is pivotally connected to a lifting frame which in its turn is detachably mounted to the end section of the conduit behind the termination head. The system of the present invention has a simple, space-saving and cost-efficient construction.

According to an embodiment of the invention, the lifting yoke comprises a first leg and a second leg at its lower end, wherein these first and second legs are configured to engage with said structural part of the termination head on opposite sides thereof.

Another embodiment of the invention is characterized in: - that the l ifting yoke is provided with a connecting device for releasably connecting the l ifting yoke to the term ination head ;

- that the connecting device comprises a cyl indrical first connecting member wh ich is moveably mounted to said first leg so as to be moveable between an advanced position , in wh ich the first connecting member is in engagement with a first connecting hole provided in said structural part, and a retracted position , in wh ich the first connecting member is out of engagement with the first connecting hole; - that the connecting device comprises a cyl indrical second connecting member wh ich is moveably mounted to said second leg so as to be moveable between an advanced position , in wh ich the second connecting member is in engagement with a second connecting hole provided in said structural part, and a retracted position , in wh ich the second connecting member is out of engagement with the second connecting hole; and

- that the termination head is pivotable in relation to the l ifting yoke about said first and second connecting members .

Thus, the joint between the l ifting yoke and the termination head is formed by said connecting members and said connecting holes, and the l ifting yoke may be pivotal ly connected to the termination head is a simple and rel iable manner by a movement of the connecting members into engagement with the associated connecting holes.

Another embod iment of the invention is characterized in : - that the first connecting member is moveable between the advanced position and the retracted position by means of a first hydraul ic cyl inder provided on said first leg ; and - that the second connecting member is moveable between the advanced position and the retracted position by means of a second hydraulic cylinder provided on said second leg.

Hereby, no additional tool is required for actuating the connecting members.

Another embodiment of the invention is characterized in:

- that the connecting device comprises a first locking member which is moveable between a locking position, in which the first connecting member is prevented by the first locking member from moving from the advanced position to the retracted position, and a unlocking position, in which the first connecting member is allowed to move from the advanced position to the retracted position; and

- that the connecting device comprises a second locking member which is moveable between a locking position, in which the second connecting member is prevented by the second locking member from moving from the advanced position to the retracted position, and a unlocking position, in which the second connecting member is allowed to move from the advanced position to the retracted position. Thus, an unintentional release of the lifting yoke from the termination head is prevented by the locking members.

Further advantages as well as advantageous features of the system of the present invention will appear from the following description and the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, a specific description of preferred embodiments of the invention cited as examples follows below. In the drawings:

Fig 1 is a perspective view of a system according to an embodiment of the present invention with the termination head fixed to an end section of a conduit, as seen with the termination head in a vertical position,

Fig 2 is a perspective view of the termination head included in the system of Fig 1 , Fig 3 is a perspective view of the lifting yoke included in the system of Fig 1 ,

Fig 4 is a perspective view from another direction of the lifting yoke,

Fig 5 is a lateral view of the system of Fig 1, as seen with the termination head in a vertical position,

Fig 6 is a longitudinal section through the termination head and the conduit fixed to the termination head,

Figs 7a and 7b are cuts according to the line VII-VII in Fig 6, with the locking member shown in different positions, Figs 8-12 are lateral and perspective views illustrating different steps in a process of connecting the termination head to a subsea landing unit, and

Fig 13 is a rear view corresponding to Fig 10.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS THE INVENTION A system 10 according to an embodiment of the present invention is illustrated in Figs 1-13. The system 10 is to be used for supporting an end section 1 of a flexible first conduit when the conduit is lowered into the sea and installed at the seabed in order to be connected to an end section of a second conduit (not shown) which in advance has been installed at the seabed fixed to a subsea support structure.

The system 10 comprises a termination head 20, which is to be permanently fixed to the end section 1 of the above-mentioned first conduit. The end section 1 of this conduit is intended to be fixed to the termination head 20 during and after the connection of the two conduits to each other. In the illustrated embodiment, the termination head 20 comprises a base frame 21, a tubular body 22 and a holding plate 23 provided at the front end of the tubular body 22. The tubular body 22 and the holding plate 23 are rigidly mounted to the base frame 21. The tubular body 22 is configured to surround the end section 1 of the conduit. In the illustrated example, the end section 1 of the conduit extends through an opening at the rear end of the tubular body 22 and through an opening at the front end of the tubular body. A radially extending mounting collar 2 is fixed to the end section 1 of the conduit at the front end thereof. This mounting collar 2 is received in an annular recess 3 provided in the envelop surface of the end section 1 of the conduit, as illustrated in Fig 6. The mounting collar 2 surrounds the end section 1 of the conduit and is secured to the termination head 20, preferably to the end section of the tubular body 22, for instance by means of fastening members 4 in the form of screws or bolts, so as to thereby secure the end section 1 of the conduit to the termination head 20.

The system 10 also comprises a lifting yoke 40, which has an upper end 41 and a lower end 42. An attachment 43 configured for engagement with a l ifting wire (not shown) is provided on the l ifting yoke 40 at the upper end 41 thereof. In the il lustrated embod iment, said attachment 43 has the form of a horizontal shaft. The l ifting yoke 40 is configu red to be detachably con nected to the termination head 20 through a joint 44 formed between the lower end 42 of the l ifting yoke and a rear structural part 24 of the termination head 20. In the il lustrated example, said rear structural part 24 constitutes a rear part of the tubu lar body 22. When the l ifting yoke 40 is connected to the termination head 20, the termination head is pivotable in relation to the l ifting yoke 40 about a horizontal pivot axis 45 formed by said joint 44, the term ination head being pivotable about said pivot axis 45 between a vertical position (see Figs 1 and 5) and a horizontal position (see Figs 9-1 3). The joint 44 between the term ination head 20 and the l ifting yoke 40 has such a position on said structural part 24 of the term ination head that the pivot axis 45 extends across the centre axis of the end section 1 of the condu it that is attached to the term ination head 20.

The l ifting yoke 40 is curved and configured to extend through a recess 25 in the hold ing plate 23 of the term ination head 20 when the term ination head is in the vertical position in relation to the l ifting yoke. The attachment 43 for the l ifting wire is so positioned on the l ifting yoke 40 that the centre axis of the end section 1 of the condu it that is attached to the term ination head 20 is al igned with a l ifting wire that is engaged with the attachment 43, when the l ifting yoke 40 is suspended through the l ifting wire with the term ination head 20 in the vertical position in relation to the l ifting yoke.

The term ination head 20 is provided with a first stop surface 26 wh ich is configured to abut against a correspond ing first stop su rface 46 on the l ifting yoke 40 when the termination head is in the vertical position in relation to the l ifting yoke. Furthermore, the termination head 20 is provided with a second stop surface 27 which is configured to abut against a corresponding second stop surface 47 on the lifting yoke 40 when the termination head is in the horizontal position in relation to the lifting yoke. In the illustrated embodiment, said first and second stop surfaces 26, 27 of the termination head 20 are constituted by an edge on the holding plate 23 and a rear end surface of the tubular body 22, respectively. The stop surfaces 26, 27, 46, 47 limit the pivotability of the termination head 20 in relation to the lifting yoke 40 and thereby improve the safety in the use of the system 10.

The lifting yoke 40 comprises a first leg 48a and a second leg 48b at its lower end 42. The legs 48a, 48b are parallel with each other and configured to engage with said structural part 24 of the termination head 20 on opposite sides thereof. An opening 49 is provided in the lifting yoke 40 between the legs 48a, 48b, this opening 49 being so designed that the lifting yoke 40, when the termination head 20 is in the horizontal position in relation to the lifting yoke 40, is allowed to sit astraddle of a conduit that is attached to the termination head, as illustrated in Figs 11 and 13. In the illustrated embodiment, the lifting yoke 40 is formed by a first lateral plate 50a, a second lateral plate 50b and a back-plate 51. The lateral plates 50a, 50b are parallel with each other and the back-plate 51 extends between the lateral plates, each lateral plate 50a, 50b being fixed to the back-plate 51 along the rear edge of the lateral plate. In the illustrated example, the above-mentioned opening 49 is formed by a recess in the back-plate 51 at the lower end thereof, and the above-mentioned attachment 43 is formed by a shaft provided between the lateral plates 50a, 50b at the upper ends thereof. The lifting yoke 40 is provided with a connecting device 60 for releasably connecting the lifting yoke to the termination head 20. This connecting device 60 comprises a cylindrical first connecting member 61a which is moveably mounted to said first leg 48a of the lifting yoke so as to be moveable between an advanced position (see Fig 6), in which the first connecting member 61a is in engagement with a first connecting hole 31a provided in said structural part 24 of the termination head, and a retracted position, in which the first connecting member 61a is out of engagement with the first connecting hole 31a. The connecting device 60 also comprises a cylindrical second connecting member 61b which is moveably mounted to said second leg 48b of the lifting yoke so as to be moveable between an advanced position (see Fig 6), in which the second connecting member 61b is in engagement with a second connecting hole 31b provided in said structural part 24 of the termination head, and a retracted position, in which the second connecting member 61b is out of engagement with the second connecting hole 31b. In the illustrated embodiment, the termination head 20 is pivotable in relation to the lifting yoke 40 about said first and second connecting members 61a, 61b. Thus, the joint 44 between the termination head 20 and the lifting yoke 40 is in this case formed by the connecting members 61a, 61b and the associated connecting holes 31a, 31b.

In the illustrated embodiment, the first connecting member 61a is slidably received in a first sleeve 62a which is mounted to said first lateral plate 50a of the lifting yoke at the lower end thereof, the first connecting member 61a being moveable between the advanced position and the retracted position by means of a first hydraulic cylinder 63a mounted to the first sleeve 62a. In the corresponding manner, the second connecting member 61b is slidably received in a second sleeve 62b which is mounted to said second lateral plate 50b of the lifting yoke at the lower end thereof, the second connecting member 61b being moveable between the advanced position and the retracted position by means of a second hydraulic cylinder 63b mounted to the second sleeve 62b. The first connecting member 61a is linearly moveable in its axial direction by the first hydraulic cylinder 63a and connected to a piston rod 64a of this hydraulic cylinder, as illustrated in Fig 6. The second connecting member 61b is linearly moveable in its axial direction by the second hydraulic cylinder 63b and connected to a piston rod 64b of this hydraulic cylinder.

In the illustrated embodiment, the connecting device 60 comprises a first locking member 65a configured for engagement with the first connecting member 61a and a second locking member 65b configured for engagement with the second connecting member 61b. The first locking member 65a is moveable between:

- a locking position (see Fig 7a), in which the first locking member 65a is in engagement with a recess provided in the first connecting member 61a and thereby prevents the first connecting member 61a from moving from the advanced position to the retracted position; and

- an unlocking position (see Fig 7b), in which the first locking member 65a is out of engagement with said recess in the first connecting member 61a and thereby allows the first connecting member 61a to move from the advanced position to the retracted position.

In the illustrated example, the first locking member 65a is rotatably mounted to the first sleeve 62a and provided with a handle 66a, by means of which the first locking member 65a may be rotated about its longitudinal axis and thereby moved between said locking and unlocking positions. The first locking member 65a comprises a pin 67a wh ich is fixed to the hand le 66a . The pin 67a is provided with a recess 68a wh ich faces the first connecting member 61 a when the first locking member 65a is in said unlocking position to thereby allow the first connecting member 61 a to sl ide in its axial d irection in relation to the first locking member.

In a correspond ing manner, the second locking member 65b is moveable between :

- a locking position , in wh ich the second locking member 65b is in engagement with a recess provided in the second connecting member 61 b and thereby prevents the second connecting member 61 b from moving from the advanced position to the retracted position ; and

- an unlocking position , in wh ich the second locking member 65b is out of engagement with said recess in the second connecting member 61 b and thereby al lows the second connecting member 61 b to move from the advanced position to the retracted position .

In the il lustrated example, the second locking member 65b is rotatably mounted to the second sleeve 62b and provided with a handle 66b, by means of wh ich the second locking member 65b may be rotated about its long itud inal axis and thereby moved between said locking and unlocking positions. The second locking member 65b comprises a pin 67b wh ich is fixed to the handle 66b. The pin 67b is provided with a recess wh ich faces the second connecting member 61 b when the second locking member 65b is in said unlocking position to thereby allow the second connecting member 61 b to sl ide in its axial d irection in relation to the second locking member. The termination head 20 is connectable to a subsea landing unit 70 by being lowered downwards onto said landing unit 70 so as to come to bear against it, as illustrated in Figs 9-13. Thus, the landing unit 70 constitutes a landing platform for the termination head 20. The termination head 20 is provided with guiding means 28, 29a, 29b configured to co-operate with corresponding guiding means on the landing unit 70 so as to guide termination head 20 into a correct position in relation to the landing unit 70 when the termination head

20 is lowered downwards into contact with the landing unit 70. When the termination head 20 has been properly landed onto the landing unit 70 in front of the end section of the second conduit (not shown), the lifting yoke 40 may be detached from the termination head 20 and retrieved to the surface vessel.

In the illustrated embodiment, said guiding means of the termination head 20 comprise a ring-shaped guide member 28, which is mounted to the base frame 21 of the termination head 20 so as to project in a horizontal direction therefrom. This guide member 28 is configured to engage with a guide member in the form of a vertically extending guide post 78 detachably mounted to the landing unit 70. The guide member 28 is to pass over the top of the guide post 78 when the termination head 20 is lowered towards the landing unit 70 and then slide downwards along the guide post until the base frame

21 and the tubular body 22 of the termination head makes contact with the landing unit 70. In the illustrated example, the base frame 21 of the termination head is configured to rest against a horizontal beam 71 on the landing unit, whereas the tubular body 22 of the termination head is configured to rest against a seat 72 on the landing unit.

In the illustrated embodiment, said guiding means of the termination head 20 further comprise two inclined guide members 29a, 29b (see Figs 1 and 12), which are arranged opposite each other and project downwards from the lower end of the holding plate 23. These guide members 29a, 29b are configured to engage with the horizontal beam 71 of the landing unit 70 on opposite sides thereof, as illustrated in Fig 12.

In the illustrated embodiment, gripping members 30a, 30b (see Figs 1 and 13) are pivotally mounted to the termination head 20 and configured to engage with protrusions 73a, 73b (see Fig 13) provided on opposite sides of the horizontal beam 71 of the landing unit when the termination head 20 has been landed onto the landing unit 70 to thereby keep the termination head secured to the landing unit.

The illustrated termination head 20 is provided with two male-like alignment members 32 in the form of spears, which are configured to come into contact with corresponding female-like alignment members in the form of spear funnels on the subsea support structure that supports the end section of the above-mentioned second conduit (not shown) in order to align the end section 1 of the first conduit with the end section of the second conduit when these end sections are brought into contact with each other after the landing of the termination head 20 onto the landing unit 70.

Different steps in a process of connecting a termination head 20 and an associated end section 1 of a conduit to a subsea landing unit 70 are illustrated in Fig 8-13. A termination head 20 is fixed to each end of a conduit that is to be lowered into the sea from a surface vessel in order to be installed at the seabed. The first end of the conduit and the associated termination head is first lowered into the sea and installed at the seabed by means of a lifting yoke 40 of the above-mentioned type or in any other suitable manner, for instance by means of lifting wires attached to lifting points 33 (see Fig 2) provided on the termination head 20. Before the lowering of the second end 1 of the conduit into the sea, the second end 1 of the conduit and the associated termination head 20 is held in a vertical position, as illustrated in Fig 1. The last-mentioned termination head 20 may be pre-mounted to the second end 1 of the conduit without being connected to the lifting yoke 40. In this case, the lifting yoke 40 is connected to the termination head 20 before the lowering of the second end 1 of the conduit and the termination head 20 into the sea. As an alternative, the lifting yoke 40 may be connected to the termination head 20 before the termination head is mounted to the second end 1 of the conduit. The termination head 20 and the second end 1 of the conduit is lowered into the sea while hanging in a crane hook of a hoisting device through a lifting wire (not shown) attached to the attachment 43 of the lifting yoke 40. When the termination head 20 and the second end 1 of the conduit leave the vessel, they are in the vertical position. When the termination head 20 and the second end 1 of the conduit come closer to the seabed they will pivot in relation to the lifting yoke 40 and assume an inclined position, as illustrated in Fig 8. The termination head 20 is lowered towards the landing unit 70 in such a manner that the ring-shaped guide member 28 on the termination head will come into engagement with the guide post 78. The termination head 20 is then lowered further downwards while being guided along the guide post 78, as illustrated in Fig 9, until the base frame 21 and the tubular body 22 of the termination head 20 come to bear against the horizontal beam 71 and the seat 72 of the landing unit 70, as illustrated in Figs 10-13. The termination head 20 and the second end 1 of the conduit will assume a horizontal position when landed onto the landing unit 70. Thereafter, an ROV (ROV = Remotely Operated Vehicle) is made to grip the handles 66a, 66b of the locking members 65a, 65b in order to move the locking members from the locking position to the unlocking position. The hydraulic cylinders 63a, 63b are then actuated to pull each connecting member 61a, 61b from its advanced position to its retracted position, to thereby allow the lifting yoke 40 to be released from the termination head 20 and retrieved to the vessel.

The lifting yoke 40 may also be used for handling a conduit which has previously been installed at the seabed, in order to lift an end section of the conduit and an associated termination head 20 from the seabed towards a surface vessel. In this case, the lifting yoke 40 is connected to the termination head 20 at the seabed. Guiding members 34 (see Fig 2) are provided at the connecting holes 31a, 31b of the termination head 20 in order to assist the guiding of the connecting members 61a, 61b of the lifting yoke 40 into the correct position in relation to the connecting holes 31a, 31b and thereby facilitate a subsea connection of the lifting yoke 40 to the termination head 20. To be able to co-operate and come into engagement with the guiding members 34, the connecting members 61a, 61b are to be held in the position illustrated in Figs 3 and 4, i.e. with the connecting members 61a, 61b projecting a short distance beyond the inner surface of the lateral plates 50a, 50b of the lifting yoke 40.

The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.