Support structure

Abstract

A support structure (1) comprising a base portion (5), an attachment portion (7) configured to connect to a J-tube (100), a support channel (9) extending in a longitudinal direction and arranged between the base portion (5) and the attachment portion The support structure further comprises a bell-mouth-receiving room (23) between the support channel and the attachment portion. The attachment portion comprises a receiving structure (11) defining a receiving space (15) configured to receive a portion of the J-tube and a radially facing aperture (13) for entrance and exit of the J-tube. The receiving space is configured to accommodate a tube portion with a diameter that is larger than the aperture width.

Description

SUPPORT STRUCTURETechnical Field

[0001] The present disclosure relates to installation of offshore umbilicals and electrical power cables. In particular, it relates to the interface between their extension along the seabed and the portion entering a structure installed offshore, such as a wind turbine tower supported on the seabed, an offshore substation or a platform.Background Art

[0002] When connecting subsea umbilicals or cables to structures supported on the seabed, it is common to pull them into a so-called J-tube that is attached to the structure. The J-tube is a curved metal tube, typically formed with a J-shape, which extends vertically upwards along the structure and with a lower, curved portion. The lower end is typically provided with a bell-mouth.

[0003] The bell-mouth facilitates pulling the umbilical or cable into and up through the J-tube with a pulling string.

[0004] The bell-mouth, which constitutes the lowest portion of the J-tube, is normally positioned at a distance above the seabed. Thus, the umbilical or cable extends from the seabed and some distance upwards before entering the J-tube. It is known to provide a support structure to support and protect this part of the umbilical or cable. Such support structures can be several meters long and weigh several hundreds of kilograms.

[0005] Furthermore, it is known to secure the support structure to the J-tube with locking means. However, installation of the support structure and securing it to the J-tube can be cumbersome and time-consuming. An ROV (remotely operated vehicle) is typically used for installation of the support structure. However, J-tubes are often installed closed together, leaving too little space for operating the ROV. The present disclosure presents an alternative support structure that is installed and connected to the J-tube in a swift manner.Summary of invention

[0006] According to a first aspect of the present disclosure, there is provided a support structure comprising a base portion, an attachment portion configured to connect to a J-tube, a support channel extending in a longitudinal direction and arranged between the base portion and the attachment portion, and a bell-mouth-receiving room between the support channel and the attachment portion. The attachment portion comprises a receiving structure defining a receiving space configured to receive a portion of the J-tube and a radially facing aperture for entrance and exit of the J-tube. The receiving space is configured to accommodate a tube portion with a diameter that is larger than the aperture width.

[0007] When stating that the aperture is radially facing, it is meant that it faces in a direction crosswise to the longitudinal direction, i.e. crosswise to the direction of a supported cable. The term crosswise shall be construed to mean not merely perpendicular, but rather such that the aperture is able to receive a portion of a J-tube that extends in the longitudinal direction.

[0008] Since the receiving space is configured to accommodate a tube portion, such as a portion of the bell-mouth, with a diameter that is larger than the aperture width, the support structure can be connected to the J-tube by moving the receiving structure towards the bell-mouth. Thus, by moving the receiving structure along the increasing diameter of the bell-mouth, the support structure becomes attached to the J-tube. The only way to disconnect the support structure from the J-tube is to move the receiving structure in the opposite direction, upwards along the J-tube.

[0009] The support structure can thus be installed quickly and easily. Moreover, the support structure does not need further equipment for connection to the J-tube. In particular, one avoids the need for an ROV for locking the support structure to the J-tube.

[0010] This design of the support structure can prevent uplift without the need of an additional lock for securing the support structure to the J-tube.

[0011] In some embodiments, the support channel can exhibit a curved shape along the longitudinal direction.

[0012] The receiving structure can have the shape of an open circle.

[0013] The receiving structure can comprise two space-defining elements with a gap between them.

[0014] The inner face of the receiving structure can have a plurality of contact elements protruding into the receiving space. The contact elements can ensure low friction against the J-tube to facilitate sliding along the J-tube. Furthermore, the contact elements can protect the coating of the J-tube.

[0015] The contact elements can be made of a thermoplastic material.

[0016] The support structure can be made of a non-metallic material. In some embodiments, the material is a composite material (i.e. a polymer matrix reinforced with fibers), such as FRP (fiber reinforced polymer) or GRP (glass fiber reinforced polymer).

[0017] In some embodiments of the support structure, the base portion comprises a curved lower support face with an upwardly curving curvature.

[0018] The bell-mouth of a J-tube has an increasing diameter towards the end, such as the shape of the wider end of a trumpet. It is typically a curved shape, such that the rate of the diameter growth increases towards the end. However, the skilled reader will appreciate that the protection structure discussed herein will also be useful with a lower J-tube end with a constantly increasing diameter (funnel-shaped).

[0019] The support structure can be more than 3 or even 4 meters long.Furthermore, it can weigh more than 300 kg (dry).

[0020] There is also disclosed a method of connecting a support structure to a J-tube with a bell-mouth. The support structure comprises a base portion, an attachment portion with a receiving structure, and a support channel between the attachment portion and the base portion. The method comprisesa) lowering the receiving structure onto the J-tube at a distance from the lower end of the J-tube, thereby moving the J-tube through an aperture and into a receiving space of the receiving structure;b) after step a), moving the receiving structure towards the lower end of the J-tube, until the diameter of the bell-mouth engages with the receiving structure and halts said movement;the receiving space is configured to accommodate a tube portion with a diameter that is larger than the aperture width.

[0021] Detailed description

[0022] While various features have been discussed in general terms above, a more detailed and non-limiting example of embodiment will be presented in the following with reference to the drawings, in whichFig. 1 depicts a perspective view of a support structure attached to the lower portion of a J-tube;Fig. 2 is a perspective view of a support structure;Fig. 3 is a perspective view of the support structure from another angle;Fig. 4 is a side view of the support structure being connected to a J-tube;Fig. 5 is a side view of the support structure after installation, connected to the J- tube;Fig. 6 is a rear view of the support structure;Fig. 7 is another view of the support structure installed to the J-tube;Fig. 8 is a schematic view of a receiving structure, with a portion of a bell-mouth indicated inside its receiving space;Fig. 9 is a schematic view of another embodiment of a receiving structure; and Fig. 10 is a schematic view of a further embodiment of a receiving structure.

[0023] Fig. 1 depicts a support structure 1 installed at the seabed 201. On the seabed 101 there is arranged an armour layer 203. Moreover, a concrete mattress 205 is arranged on the armour layer 203.

[0024] As appears from Fig. 1 , the support structure 1 extends between the lower part of a J-tube 100 and the armour layer 203. The J-tube 100 is attached to and extends downwards along a not shown offshore structure supported on the seabed.The offshore structure can for instance be the tower of a wind turbine or the framework of an offshore substation. As the skilled reader will appreciate, J-tubes are used for guiding cables or umbilicals from the seabed upwards towards the surface.

[0025] At the lower part of the J-tube 100, it comprises a curved portion 101.Moreover, it has a bell-mouth 103 (cf. Fig. 4) at its lower end. This shape facilitates pull-in of the umbilical or cable.

[0026] Still referring to Fig. 1 , a cable 107 is shown resting on the concrete mattress 205 and extending into the support structure 1 and further up through the J-tube 100.

[0027] The support structure 1 comprises a cover 3, which in the shown situation is arranged over the cable 107.

[0028] Fig. 2 depicts the support structure 1 without the cover 3. The support structure 1 comprises a base portion 5 that, as shown in Fig. 1 , is configured to rest on the support surface, such as the armour layer 203.

[0029] Opposite of the base portion 5, the support structure 1 has an attachment portion 7. The attachment portion 7 is configured to attach the support structure 1 to the J-tube 100. This will be discussed in further detail below.

[0030] Between the base portion 5 and the attachment portion 7, the support structure 1 comprises a support channel 9. The support channel 9 is in the shown embodiment shaped as a curved groove. It will support a curved portion of the cable 107 between its resting position on the concrete mattress 205 and its position inside the J-tube 100.

[0031] The attachment of the support structure 1 to the J-tube will now be discussed with reference to Fig. 3 to Fig. 7.

[0032] As shown in Fig. 4, and as is common in the art, the lower end of the J-tube 100 has a bell-mouth 103 with an enlarged diameter. Above the bell-mouth 103, the J-tube 100 has a cylindrical portion 105 with a diameter that is smaller than the enlarged diameter of the bell-mouth 103.

[0033] The shape of the attachment portion 7 is shown with the perspective view of Fig. 3. It comprises a receiving structure 11 , which in the shown embodiment is in the form of an arced structure or an open circle. The receiving structure 11 has anaperture 13 configured to allow the cylindrical portion 105 of the J-tube 100 to pass through it. Furthermore, the receiving structure 11 has a receiving space 15 within the aperture 13. The receiving space 15 is configured to receive the cylindrical portion 105 of the J-tube 100 when the cylindrical portion 105 passes through the aperture 13.

[0034] This is shown in Fig. 4. The attachment portion 7 of the support structure 1 is lowered onto the cylindrical portion 105 of the J-tube 100. The cylindrical portion 105 then passes through the aperture 13 of the receiving structure 11 and into the receiving space 15.

[0035] Then, as shown in Fig. 5, the support structure 1 is lowered further. The receiving structure 13 slides down along the J-tube 100 towards the bell-mouth 103. Moreover, the support structure 1 is pivoted so that the base portion 5 lands on the armour layer 203.

[0036] Since the diameter of the bell-mouth 103 is larger than the aperture 13, the attachment portion 11 of the support structure 1 cannot be lifted off from the bellmouth 103 when the support structure 1 is in this position relative to the bell-mouth 103. The attachment portion 11 is thus connected to the J-tube 100.

[0037] If the operator wishes to disconnect the support structure 1 from the J-tube 100, the attachment portion 11 must be moved upwards away from the bell-mouth 103 towards the slimmer cylindrical portion 105. At this position, the J-tube 100 can be moved out of the receiving space 15, through the aperture 13.

[0038] Fig. 6 depicts the support structure 1 from an angle facing the attachment portion 7. Fig. 7 shows the support structure 1 installed on the J-tube 100, with the attachment portion 7 connected to the bell-mouth 103 of the J-tube 100.

[0039] Fig. 8 is a schematic illustration of the receiving structure 11 , configured for accommodating a portion of the bell-mouth 103. The aperture width 13a of the aperture 13 is indicated with a dashed arrow. Furthermore, the bell-mouth 103 is indicated with the dashed circle, while the diameter 103a of the bell-mouth 103 is indicated with a dashed arrow. Fig. 8 illustrates that the receiving space 15 can accommodate a tube portion, such as the shown part of the bell mouth 103, with a diameter that is larger than the aperture width 13a.

[0040] In the embodiment shown in Fig. 8, the inner shape of the receiving structure 11 has the shape of an open circle. Advantageously, it can have a circular shape with a constant radius. In this manner, forces between the receiving structure 11 and the bell-mouth 103 will be evenly distributed.

[0041] An alternative design of the receiving structure 11 is shown in Fig. 9. In this embodiment, the receiving structure 11 comprises two space-defining elements 11a. As with the previous embodiment, the receiving space 15 is configured to accommodate a portion of the bell-mouth 103 with a diameter that is larger than the aperture width 13a of the aperture 13. Moreover, shown at the upper portion of Fig.9, there is a gap 17 between the two space-defining elements 11a. The gap width 17a of the gap 17 is smaller than the aperture width 13a. The gap width 17a should advantageously be such that the cylindrical portion 105 of the J-tube 100 is prevented to move through it.

[0042] The space-defining elements 11a can advantageously be shaped as portions of a circle, as shown in Fig. 9.

[0043] Yet another embodiment is shown in Fig. 10. In this embodiment, the receiving structure 11 comprises three space-defining elements 11a. Hence, in this embodiment, there is defined one aperture 13 between two of the space-defining elements 11 a and two gaps 17.

[0044] The receiving structure 11 shown in Fig. 10 comprises contact elements 19. The contact elements 19 are attached to the inner face of the respective spacedefining elements 11a and are configured to contact the J-tube 100.

[0045] Reference is again made to Fig. 2 and Fig. 3. The receiving structure 11 is supported by two arms 21. The two arms 21 hold the receiving structure 11 at a longitudinal distance from the support channel 9. With the term “longitudinal” is meant the direction along a cable or umbilical to be supported by the support channel 9 and extend into the J-tube 100.

[0046] The two arms 21 extend on respective sides of a bell-mouth-receiving room 23. The bell-mouth-receiving room 23 is downwardly open, so that a portion of the bell-mouth 103 of the J-tube 100 can be received when lowering the support structure 1 from above. When the support structure 1 is in its installed position, suchas shown in Fig. 1 and Fig. 5, the upper end of the support channel 9 is aligned with the opening of the bell-mouth 103, such that the cable 107 can extend from the support channel 9 and into the J-tube 100.

[0047] The support structure 1 can advantageously be made of a non-metallic material. For instance, it can be made of a composite. An example of a suitable composite is GRP (glass fiber-reinforced polymer).

[0048] Reference is again made to Fig. 5. The base portion 5 comprises a curved lower support face 5a with an upwardly curving curvature. The curvature of the curved lower support face 5a allows some flexibility in vertical distance between the bell-mouth 103 of the J-tube 100 and the seabed 201 (or the concrete mattress 205).

Claims

Claims1. A support structure (1) comprising- a base portion (5);- an attachment portion (7) configured to connect to a J-tube (100);- a support channel (9) extending in a longitudinal direction and arranged between the base portion (5) and the attachment portion (7);- a bell-mouth-receiving room (23) between the support channel (9) and the attachment portion (7);wherein the attachment portion (7) comprises a receiving structure (11) defining a receiving space (15) configured to receive a portion of the J-tube (100) and a radially facing aperture (13) for entrance and exit of the J-tube (100), characterized in that the receiving space (15) is configured to accommodate a tube portion with a diameter that is larger than the aperture width (13a).

2. A support structure (1 ) according to claim 1 , wherein the support channel (9) exhibits a curved shape along the longitudinal direction.

3. A support structure (1) according to claim 1 or claim 2, wherein the receiving structure (11) exhibits the shape of an open circle.

4. A support structure (1) according to claim 1 or claim 2, wherein the receiving structure (11 ) comprises two space-defining elements (11 a) with a gap (17) between them.

5. A support structure (1 ) according to one of the preceding claims, wherein the inner face of the receiving structure (11) comprises a plurality of contact elements (19) protruding into the receiving space (15).

6. A support structure (1) according to one of the preceding claims made of a non-metallic material.

7. A support structure (1) according to one of the preceding claims, wherein the base portion (5) comprises a curved lower support face (5a) with an upwardlycurving curvature.

8. A method of connecting a support structure (1) to a J-tube (100) with a bellmouth (103), wherein the support structure (1) comprises a base portion (5), an attachment portion (7) with a receiving structure (11 ), and a support channel (9) between the attachment portion (7) and the base portion (5), the method comprisesa) lowering the receiving structure (11) onto the J-tube (100) at a distance from the lower end of the J-tube, thereby moving the J-tube through an aperture (13) and into a receiving space (15) of the receiving structure (11);b) after step a), moving the receiving structure (11 ) towards the lower end of the J-tube, until the diameter of the bell-mouth (103) engages with the receiving structure and halts said movement;wherein the receiving space (15) is configured to accommodate a tube portion with a diameter that is larger than the aperture width (13a).

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