NO348159B1

NO348159B1 - Bend guide structure

Info

Publication number: NO348159B1
Application number: NO20201010A
Authority: NO
Inventors: Alf Erik Rød
Original assignee: Nexans
Priority date: 2020-09-14
Filing date: 2020-09-14
Publication date: 2024-09-09
Also published as: NO20201010A1

Description

Bend guide structure

TECHNICAL FIELD

The invention relates to a bend guide structure for controlling the bending of a cable, a cable housing and a field joint arrangement.

More specifically the invention may be used for protection of the vulnerable regions where a flexible cable runs out from a cable housing of a field joint.

BACKGROUND

When installing long lengths of submarine cable, the weight of the cable or the volume of the cable, sets limitations for the actual length an installation vessel can handle at one time. To enable the installment of the required length of the cable, sections of cables are installed separately and then connected by field joints to obtain the required cable length. A field joint is a joint to connect cables outside the factory. The procedure is to install a first section of a cable, then go back to port to pick up an additional cable section, bring it out to the installation site of the first cable section and position the additional cable section at the end of the first cable section. The adjacent ends of the cable sections are connected by a field joint. The procedure may be repeated until the required cable length is obtained.

Whereas the cables are typical flexible, the field joint may be of a rigid or a semi rigid type. A field joint may also be applied if damage occurs on a cable or cable joint that is already installed. The cable will be installed with an initial field joint in an inline position between the cable to be repaired and a spare cable. Secondly a hairpin joint will be jointed between the spare cable and the second cable end. A hairpin joint is when both cables jointed are hanging down into the sea. The field joint can therefore assume the position both as an inline joint or as a hairpin joint.

Prior to the actual installation of the cable subsea, the cable end sections are connected by a field joint on the boat deck. After the joint assemblage, the installation process continues and the joint needs to be guided from the boat deck and into the water. Usually over a chute or laying wheel at the stern of the boat.

The field joint comprises two cables that are connected by an electrical joint and then placed in a cable housing for protection. The two cables are typically flexible cables which comprise an outer armour. The cable housing is provided as a rigid outer housing made of metal or composite material to mechanical protection for the electrical joint and provide tensile strength to the field joint. The cable housing is arranged with openings for the cables connected by the electrical joint and is provided with armour termination blocks at the end portions of the cable housing. The transition region between rigid cable housing and the flexible cable running out from the cable housing opening outside the armour termination, appears as a critical region in need of protection.

This need has been recognized within the technical field for some time and various protectors such as bend stiffeners and bend restrictors have been constructed to avoid excessive bending, such as overbending of the cable at the interface point between the flexible cable and cable housing. Typical scenarios prone to overbending and concurrent damage of the cable are; handling of the cable on deck with the installation wheel/ chute or when the joint is subjected to an angled touch down on the seabed.

Prior art solutions include arranging a bend stiffener at each end of the rigid or semi-rigid joint housing, or alternatively a bend restrictor. A known bend restrictor solution comprises an assembly of rigid sections arranged with flexible links positioned in between the rigid sections. This arrangement has the appearance of a pipe protection to be positioned over the cable. The protection can be made to bend to a certain degree before the flexible link locks and restricts further movement to avoid overbending of the cable. Usually the protection consists of 8-11 rigid sections which combined usually bend to a 90 degree angle from the rigid joint. This bend guide structure is arranged for attachment to each end of the rigid or semi-rigid joint housing.

This prior art bend restrictor protects the cable both when going overboard and when hitting the sea bottom. However, this solution consists of many parts which makes for an expensive solution, as well as a time-consuming solution to assemble offshore, and time offshore is expensive. The complexity, price and installation time of this bend restrictor are drawbacks that makes this bend restrictor a disadvantageous choice to the applicant.

A bend stiffener solution is designed to resist bending and makes a curve at a given tension and a given angel that fits the cable. In accordance with a prior art solution the bending curve of the bend stiffener is defined by the dimensions and elasticity of components such as elastomers, polyurethane, rubber. The technical features of this bending stiffener are calculated based on cable parameters, angles, tension and minimum bending radius. The problem with this solution is that the tension and angle is a variable parameter for a subsea cable installation. The depth varies and the installation handling differs in accordance with the installation scenario. It is almost impossible to design for several tension/angle scenarios. If the tension input is set too high, the bend stiffener will be too stiff when hitting the sea bottom, and risks overbending the cable. While too soft might not protect the cable going over the stern of the boat. A bend stiffener is an acceptable solution when there is a fixed point to a moving object, such as an offshore platform where the bend stiffener can be designed to protect against dynamic fatigue of a cable. The bend stiffener solution will however not work properly for an installation of a field joint, and has become in many situations a non-applicable solution for the applicant.

Further prior art solutions are disclosed in the following publications;

KR101467112 describes an armour clamp used to facilitate a connection work for submarine cable.

BR202015031996 discloses a curvature restrictor for the protection of conductive and umbilical tubes to avoid bending the tube to a smaller radius than the minimum radius of curvature.

WO9815865 shows a bend limiting boot assembly for protection of optical fibre. The stiffness of the boots acts to reduce bend in the cable at the joint assembly, and thus reduce the likelihood of damage to the fiber optic cable at the cable joint.

EP3158160 describes a bend stiffener for resisting excessive bending of a flexible riser where it meets a rigid structure. The bending stiffener has a frusto-conical shaped sleeve with a through-going channel for the flexible riser.

US2018097348 discloses a restrictor device for protecting the cable from excessive bending. The restrictor device includes two or more restrictor members having a helix shape extending along a longitudinal axis.

GB2102044 shows a bending restrictor for a riser, arranged with a passage for receiving the riser. The diameter of the passage allows a very narrow amount of bending in lower portions near the well head apparatus. The diameter of the passage increases progressively allowing a greater amount of bending in the vertically ascending direction.

GB777597 discloses submarine cables and in particular means for preventing such a cable from undergoing severe local deformation where it enters a joint or other rigid accessory between two lengths of the cable or when it is being picked up or lowered by a rope attached to the cable at a joint or elsewhere.

None of these publications discloses a bend restrictor for controlling the bending of a flexible cable at the interface between the cable and the cable joint such as a field joint. The bend restrictors and bend stiffeners as described in the publications are adapted for riser, tubes, optical fibers and also for restricting the bending of the cable itself, but not to protect the specific local region of a flexible cable as running out from cable housing.

Based on these mentioned challenges a need has evoked within the field to provide an improved bend guide structure for protection of the region of the cable extending from a cable housing.

Thus, an object of the invention is to provide a solution prepared for controlling the bending radius of a cable adjacent to its interface with a cable housing, especially a field joint where the cable housing accommodates an electrical joint connecting two cables.

A further object is to provide a solution that provides an efficient protection during multiple installation and depth scenarios, as well as providing a satisfactory protection when being handled on the boat deck, when going overboard and when hitting the sea bottom.

It is further an object of the invention that the bend guide structure is simple in manufacturing and installation.

It is also an object to provide a solution that facilitates installment, thereby minimizing installation time, and hence installation costs.

SUMMARY

The invention concerning a bend guide structure, a cable housing arranged with the bend guide structure and a field joint arrangement comprising the bend guide structure, has been set forth in the independent claims. Further additional features are set forth in the dependent claims.

The invention concerns a bend guide structure for controlling the bending of a cable extending from a cable housing, typical for subsea installation. The bend guide structure comprises a tubular part that is arranged with an interfacing end portion for attachment to the cable housing. Further, the tubular part has an inner circumferential wall forming a through-going passage comprising an inlet opening and an outlet opening for receiving and accommodating a portion of the length of the cable in the through-going passage. At least a portion of the inner circumferential wall is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage. The convex surface has a curvature away from the axial axis of the through-going passage. The radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage.

As mentioned above at least a portion of the inner circumferential wall that extends circumferentially around axial axis of the through-going passage is arranged as a convex surface. In some circumstances all of the inner circumferential wall as extending in the axial direction of the through-going passage has a convex configuration, and in other circumstances only a portion of the inner circumferential wall comprises the convex surface. For instance, an outer portion of the inner circumferential wall terminating at the outlet opening. In the latter case an inner portion of the inner circumferential wall may have a different configuration than a convex configuration, for instance a cylindrical configuration.

The bend guide structure may be made rigid. That is the bend guide structure is arranged to display a rigidity to withstand the side forces of the cable without bending. The bend guide structure may be made of metal, here a various kind of steel, aluminum, copper, bronze or other metal materials may be chosen. Alternatively, composites or other material as well as the outlay such as the lengths and outer outlay may vary according to need and material chosen.

The cable may typically comprise a flexible cable comprising 1, 3 or more conductors, or may be arranged as hybrid comprising tubes, pipes and fiber etc.

When the inner portion of the inner circumferential wall comprises a cylindrical surface and an outer portion of the inner comprises the convex surface, the radius of the through-going passage of the inner portion extending axially from the inlet opening may correspond essentially to the radius of the cable to be accommodated in the through going passage, and the through-going passage through the outer portion may gradually increases away from the axial axis of the through going passage towards the outlet opening.

The radius of curvature of the convex surface is measured to the outer curvature of the inner circumferential wall as curving away from the axial axis of the through going passage. The radius of curvature of the convex surface of the inner circumferential wall has a value that ensures that the length of the cable as accommodated in the bend guide structure is protected from overbending.

The bending radius of the cable is measured to the inside curvature of the cable when bending the cable, and the minimum bending radius is defined as the smallest allowed bending radius to which the cable may safely be bent without causing damage to the cable.

As mentioned above, the radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage. The allowed bending radius may in many cases be set equal to minimum bending radius of the cable to be accommodated in the through going passage. In other applications the allowed bending radius may be set smaller than the minimum bending radius or larger than the minimum bending radius. The allowed bending radius will then be kept within a range where the limit has a safety margin from the radius where overbending occurs.

When the allowed bending radius is set larger than the minimum bending radius, the allowed bending radius is determined based on the tension to be applied to the cable to be accommodated in the through-going passage. For instance, the allowed bending radius may be set equal to the minimum bending radius of the cable 1-2 meter.

The allowed bending radius may be selected within the range of 0.5-7.5m. The allowed bending radius may further be chosen to be within the range of 1-7.5m. The allowed bending radius may be typically be set equal to the minimum bending radius of the cable, typically within the range of 1-5m.

This inventive bending guide structure is suitable for cables having a diameter of for instance 120-300 mm. In some circumstances the diameter may even be larger than 300 mm, but also cross section down to 70mm or less may be used for specific circumstances.

The arrangement of the inventive bend guide structure enables protecting the cable at the interface or transition region the between rigid cable housing and the flexible cable as running out from the cable housing opening between the fixed point of the outer armour of the cable and the flexible cable. In addition, the bend guide structure also provide local protection from overbending as a portion of the length of the cables is accommodated in the through-going passage of the bend guide structure.

The solid and rigid configuration of the bend guide structure ensures that the different tensions(depths) or laying scenarios does not affect the outlay of the bend guide structure and it will protect the cable both at the boat deck and during touchdown at the sea bottom.

The bend guide protects the cable and sit tight at the interface part between cable and rigid cable housing, while allow the cable to be bent correctly for a shorter length axially.

The interfacing end portion of the bend guide structure may comprise a flange part which is arranged circumferentially around the inlet opening and adapted for connection to a flange part of the cable housing. A series of bolts or studs may be arranged in a circular pattern around the circumference of the flange part to provide secure mechanical locks between the bend guide structure and the cable housing.

The outer diameters of the bend guide structure and the cable housing may typically be provided correspondingly, to ease installation and provide a sustainable construction.

The bend guide structure may be made as a one-piece construction, and in this case the bend guide structure is placed in an installation position by threading the cable through the through-going passage and connecting the interfacing end portion to the cable housing. In an alternative solution the bend guide structure may comprise plural assembling parts arranged for being connected to each other, when being installed in installation position around the cable. The plural assembling parts may be prepared for later disassembling if the bend guide structure is to be demounted.

The radius of the inlet opening may correspond to the radius of the cable to be accommodated in the through going opening, and this radius may also correspond to the radius of an opening for passing the cable from the cable housing.

The invention further concerns a cable housing for accommodating an electrical joint connecting a first cable and a second cable. The cable housing is arranged with at least one bend guide structure and comprises a first housing end portion arranged with an opening for the first cable and a second housing end portion arranged with an opening for the second cable. At least one of the first housing end portion and second housing end portion is adapted for connection with the bend guide structure. The bend guide structure is arranged for controlling the bending of the either of the first cable or the second cable. The guide bend guide structure comprises a tubular part that is arranged with an interfacing end portion for attachment to either the first or second housing end portion, wherein an inner circumferential wall forms a through-going passage with an inlet opening and an outlet opening for receiving and accommodating a portion of the length of the cable in the through-going passage. At least a portion of the inner circumferential wall is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage. The convex surface has a curvature away from the axial axis of the through-going passage. The radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage.

As mentioned above, the radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage. The allowed bending radius may be selected within the range of 0.5-7.5m. The allowed bending radius may further be chosen to be within the range of 1-7.5m. The allowed bending radius may typically be selected so that it equals the minimum bending radius of either of the first or second cable to be to be accommodated in the through going passage. The minimum bending radius may be within the range of 1-5m.

In a typical embodiment, the first housing end portion is adapted for connection with a first bend guide structure arranged for controlling the bending of the first cable. The second housing end portion may then be adapted for connection with a second bend guide structure arranged for controlling the bending of the second cable. In accordance with this embodiment the first bend guide structure is arranged with an interfacing end portion for attachment to the first housing end portion and the second bend guide structure is arranged with an interfacing end portion for attachment to the second housing end portion.

The invention further concerns a field joint arrangement for subsea installation comprising

- a first cable and a second cable connected by an electrical joint,

- a cable housing accommodating the electric joint and a length of each of the first and second cable running out from the electric joint.

The cable housing comprises a first housing end portion arranged with and an opening for the running through of the first cable and a second housing end portion arranged with an opening for the running through of the second cable. The first housing end portion is arranged for connection with a first bend guide structure which is arranged for controlling the bending of the first cable. The second housing end portion is arranged for connection with a second bend guide structure which is arranged for controlling the bending of the second cable.

The first bend guide structure comprises a tubular part that is arranged with a first interfacing end portion for connection to the first housing end portion, wherein the tubular part has an inner circumferential wall forming a through-going passage with an inlet opening and an outlet opening for receiving and accommodating a portion of the length of the first cable in the through-going passage. At least a portion of the inner circumferential wall is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage. The convex surface has a curvature away from the axial axis of the through-going passage. The radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the first cable to be accommodated in the through-going passage.

The second bend guide structure comprises a tubular part that is arranged with a second interfacing end portion for connection to the second housing end portion, wherein the tubular part has an inner circumferential wall forming a through-going passage with an inlet opening and an outlet opening for receiving and accommodating a portion of the length of the first cable in the through-going passage. At least a portion of the inner circumferential wall is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage. The convex surface has a curvature away from the axial axis of the through-going passage. The radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the second cable to be accommodated in the through-going passage.

As mentioned above, the radius of curvature of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage. The allowed bending radius may be selected within the range of 0.5-7.5m. The allowed bending radius may further be chosen to be within the range of 1-7.5m. The allowed bending radius may typically be selected so that it equals the minimum bending radius of either of the first or second cable to be to be accommodated in the through going passage, wherein the minimum bending radius may be within the range of 1-5m.

The first and second cable may have the same allowed bending radius and minimum bending radius. Alternatively, the allowed bending radius and minimum bending radius of the first and second cable respectively may be different, in which case the radius of curvature of the inner circumferential wall may be set differently.

These and other characteristics of the invention will be clear from the following description of an exemplary embodiment, given as a non-restrictive example, with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic illustration of a bend stiffener according to prior art.

Fig. 2 is a schematic illustration of a prior art bend restrictor.

Fig. 3 shows an example of a bend guide structure in accordance with the invention. Fig. 4 shows a field joint comprising a cable housing arranged with two the bend guide structures.

Fig 1 shows prior art bend stiffeners 2 mounted to an end portion 3 of the cable housing 1. The cable housing 1 is arranged for accommodating and protecting a electrical joint connecting two cables. The electric joint and the cables are not illustrated in fig. 1. The bend stiffener 2 has an interfacing end portion 4 such as for instance a flange connection arranged for attaching the bend stiffener to the end portion 3 of the cable housing 2. The bend stiffener 2 has a through-going passage 5 arranged for a cable. When the electric joint connecting the two cables is accommodated in the cable housing 1 each of the cables extends from the interior of the cable housing 1 through an opening 6 in the end portion 3 and further into the through-going passage 5 of the bend stiffener 2. The diameter of the opening 6 corresponds with the diameter of the through-going passage 5. The bend stiffener 2 is arranged for preventing overbending of the cable. The bend stiffener is made of a flexible material for instance an elastomer or polyurethane with an elasticity capable of certain bending, but in a controlled way to avoid damage on the cable. As shown in the curved position illustrated by A in fig 1, the bend stiffener bends away from its initial position at a given tension, and ensures that no overbending occurs at this given tension. However, as the tension is varying depending on the installation scenario, the tension inputs varies, and the bend stiffener provides an insufficient solution lacking the versatile use in demand for the various installation scenarios of a subsea cable.

An alternative prior art solution for avoiding overbending is shown in fig 2. Fig 2. shows a bend restrictor 7 comprising plural bending restrictor elements 8 that are connected together as a snakelike assembly by flexible links 9. The flexible links 9 allows the bending restrictor elements 8 a certain degree of bending, and the bending restrictor can be set to the minimum bending radius of the cable to avoid overbending. A bend restrictor 7 is connected to each of the end portions 3 of the cable housing 1. The electric joint and the two connecting cables, when accommodated in the interior of the cable housing, is positioned with a cable length supported in the through-going passage 5 of the bend restrictor 7. This prior art bend restrictor is unfavourable due to the complexity and time consume of assemblage, as well as the incurred costs due to the installation time.

Fig 3 shows an example of the bend guide structure 10 in accordance with the invention. The bend guide structure 10 has an interfacing end portion 11 arranged for connection with the cable housing 1. In the illustrative example of fig 3, the interfacing end portion 11 is configured as a flange connection portion that will fit with a corresponding flange connection portion of the cable housing 1, see fig 4. The bend guide structure 10 as shown comprises a tubular part with a through-going passage 12 arranged with an inlet opening 13 and an outlet opening 14. The inner circumferential wall 13 of the bend guide structure 10 has a curved configuration away from the axial axis B of the through-going passage 5, when moving in the axial direction from the inlet opening 13 to the outlet opening 14. In this shown example the inner circumferential wall 15 is arranged having a convex surface with a curvature away from the axial axis B increasing the radius r of the through-going passage in the axial direction towards the outlet opening 14. In the shown example the outer surface 16 of the bend guide structure 10 has a conical configuration. However, the shape of this outer surface may vary according to need. The bend guide structure 10 as shown, is manufactured as one piece. The bend guide structure may also comprise plural parts to be assembled around the cable when it is to be installed on the cable housing, and then later the parts are disassembled when to be demounted. When the bend guide structure 10 is manufactured as one piece, the bend guide structure 10 is placed in installation position by threading the cable through the through-going passage 12 and connecting the interfacing end portion 11 to the cable housing 1.

The bend guide structure 10 as shown in fig 3 has an inner circumferential wall where the radius of curvature (rc) is for illustrative purposes set to the minimum bending radius of the cable to be accommodated in the through-going passage 12. It is thereby ensured that the length of the cable extending through the bend guide structure 10 is protected from overbending. If desirable, the radius of curvature (rc) may also be set to an allowed bending radius other than the minimum bending radius of the cable, it could be less than the minimum bending radius of the cable, and could also be larger than the minimum bending radius, but should be kept essentially within the range of 0.5-7.5meters.

Fig 4 shows a field joint 40 where the cable housing 1 is arranged with a first bend guide structure 21 and a second bend guide structure 22. The cable housing 1 accommodates an electric joint 33 which connects a first cable 31 and a second cable 32. The cable housing has a first housing end portion 23 arranged with an opening 24 for the first cable 31 and a second housing end portion 25 arranged with an opening for the second cable 32. As shown in fig 4 the shape and the dimension of the interfacing end portion 34 of first bend guide structure 21 corresponds with the first housing end portion 23 and is arranged for connection to the first housing end portion 23. This same also applies to the shape and the dimension of the interfacing end portion 35 of second bend guide structure 22 which corresponds with the second housing end portion 25 and is arranged for connection to the second housing end portion 25. The end portion of first bend guide structure 21 and the first housing end portion 23, as well as the interfacing end portion of second bend guide structure 22 and the second housing end portion 25, are arranged as corresponding flange portions for easy connection to each other. For instance, by means of bolts arranged circumferentially around the bend guide structures 21, 22, or by other means capable of secure connection to the cable housing. The opening 24 for the first cable 31 corresponds with the inlet opening of the first bend guide structure 21, and these two are set according to the diameter of the first cable 21. This same also applies for the opening 26 for the second cable, the inlet opening of the second bend guide structure 22 and the diameter of the second cable 21. A portion of a length of the two cables 31, 32 are each supported in the first and second bend guide structure 31, 32 respectively, thereby protection the vulnerable region of the cable where it passes from the rigid or semi rigid cable housing. The two cables 31, 32 may be the same cables or the cables may be different. The cables as shown in fig 4 have for illustrative purposes the same allowed bending radius and the radius of curvature rc of the inner circumferential wall is the same for both the first bend guide structure 21 and the second bend guide structure 22. The radius of curvature rc is for illustrative purposes set to the minimum bending radius.

However, the first and second cable may have different allowed bending radius and different minimum bending radius, or there may be a need for allowing different bending for each of the two cables, in which case the radius of curvature rc of the inner circumferential wall may be set differently. The allowed bending radius may be other than the minimum bending radius of the first and second cable respectively, it could be less than the minimum bending radius of the cable, and in some circumstances could also be larger than the minimum bending radius, but should be kept within the range of 0.5-7.5meters.

Fig 3 and 4 shows that an inner portion 27 of the inner circumferential wall 15 of both the first and second bend guide structure appears with a cylindrical configuration, while an outer portion 28 of the inner circumferential wall comprises the convex surface. The radius r of the through-going passage of the inner portion 27 extending axially from the inlet opening 13 corresponds essentially to the radius of the cable to be accommodated in the through-going passage 12, and further the radius of the through-going passage 12 of the outer portion 28 gradually increases away from the axial axis of the through-going passage 12 towards the outlet opening 14.

The distinction between the cylindrical and convex configuration of the inner circumferential wall as well as their individual axial extension may vary. The inner portion 27 of the inner circumferential wall 15 being arranged with the cylindrical configuration may have a shorter or longer axial extension than shown in the figs 3 and 4, and the same also applies for the outer portion 28 with the convex configuration. Further, the distinction and transition between the cylindrical configuration and the curved configuration is depending on the radius of curvature rc of selected for the outer portion 28 of the inner circumferential wall.

Claims

1. A bend guide structure (10) for controlling the bending of a cable extending from a cable housing accommodating an electric joint connecting a first cable (31) and a second cable (32), the bend guide structure (10) comprises a tubular part that is arranged with an interfacing end portion (11) for attachment to an end portion of the cable housing (1) and has an inner circumferential wall (15) configured to form a through-going passage (12) comprising an inlet opening (13) and an outlet opening (14) for receiving and accommodating a portion of the length of the cable in the through-going passage, wherein at least a portion of the inner circumferential wall (15) is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage, and that the convex surface has a curvature away from the axial axis (B)of the through-going passage (12), wherein the radius of curvature (rc) of the convex surface is selected so that it equals an allowed bending radius (BR) of the cable to be accommodated in the through-going passage (12), wherein the allowed bending radius (BR) of the cable to be to be accommodated in the through-going passage (12) cables is within the range of 0.5-7.5m.

2. Bend guide structure (10) in accordance with claim 1, wherein the allowed bending radius of the cable comprises the minimum bending radius of the cable to be to be accommodated in the through-going passage (12).

3. Bend guide structure (10) in accordance with one of the previous claims, wherein the interfacing end portion (11) comprises a flange part arranged circumferentially around the inlet opening (13) and adapted for connection to a flange part of the cable housing (1).

4. Bend guide structure (10) in accordance with one of the previous claims, wherein an inner portion (27) of the inner circumferential wall (15) extending axially from the inlet opening (13) comprises a cylindrical surface and an outer portion (28) of the inner circumferential wall (15) terminating at the outlet opening (14) comprises the convex surface.

5. Bend guide structure (10) in accordance with claim 4, wherein a radius (r) of the through-going passage (12) of the inner portion (27) corresponds essentially to the radius of the cable to be accommodated in the through-going passage (12), and the radius (r) of through-going passage (12) through the outer portion (28) gradually increases away from the axial axis (B) of the through-going passage (12) towards the outlet opening (14).

6. Bend guide structure (10) in accordance with one of the previous claims, wherein the bend guide structure (10) comprises plural assembling parts arranged for being connected to each other for installment of the bend guide structure (10) in installation position around the cable.

7. Bend guide structure (10) in accordance with one of the previous claims, wherein the bend guide structure (10) is provided as one piece construction.

8. A cable housing (1) for accommodating of an electrical joint (33) connecting a first cable and a second cable, the cable housing (1) being arranged with at least one bend guide structure (10) and comprises a first housing end portion (23) arranged with an opening (24) for the first cable and a second housing end portion (25) arranged with an opening (26) for the second cable, wherein at least one of the first housing end portion (23) and second housing end portion (25) is adapted for connection with the bend guide structure (10) which is arranged for controlling the bending of the either of the first cable or the second cable, wherein the bend guide structure (10) comprises a tubular part that is arranged with an interfacing end portion (11) for attachment to either the first or second housing end portion, and has an inner circumferential wall (15) configured to form a through-going passage (12) with an inlet opening (13) and an outlet opening (14) for receiving and accommodating a portion of the length of the first or second cable in the throughgoing passage (12) , wherein at least a portion of the inner circumferential wall (15) is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage, and that the convex surface has a curvature away from the axial axis (B) of the through-going passage (12) wherein the radius of curvature (rc) of the convex surface is selected so that it equals an allowed bending radius of the cable to be accommodated in the through-going passage (12), wherein the allowed bending radius of either of the first or second cable (32) to be to be accommodated in the through going passage is within the range of 0.5-7.5m m.

9. Cable housing (1) in accordance with claim 8, wherein the allowed bending radius comprises the minimum bending radius of either of the first or second cable (32) to be to be accommodated in the through going passage.

10. Cable housing (1) in accordance with one of the claims 8-9, wherein the first housing end portion (23) is adapted for connection with a first bend guide structure (21) arranged for controlling the bending of the first cable and second housing end portion (25) is adapted for connection with a second bend guide structure (22) arranged for controlling the bending of the second cable, wherein the first bend guide structure (21) is arranged with an interfacing end portion for attachment to first housing end portion (23) and the second bend guide structure (22) is arranged with an interfacing end portion for attachment to second housing end portion.

11. A field joint arrangement for subsea installation comprising

- a first cable (31) and a second cable (32) connected by an electrical joint (33), - a cable housing (1) accommodating the electrical joint (33) and a length of each of the first and a length of second cable (32) running out from the electrical joint (33), the cable housing (1) comprises a first housing end portion (23) arranged with an opening for the running through of the first cable (31) and a second housing end portion (25) arranged with an opening for the running through of the second cable, wherein the first housing end portion (23) is arranged for connection with a first bend guide structure (21) for controlling the bending of the first cable (31) and second housing end portion (25) is arranged for connection with a second bend guide structure (22) for controlling the bending of the second cable, wherein -the first bend guide structure (21) comprises a tubular part that is arranged with a first interfacing end portion for connection to the first housing end portion, wherein the first bend guide structure (21) has an inner circumferential wall (15) configured to form a through-going passage (12) with an inlet opening (13) and an outlet opening (14) for receiving and accommodating a portion of the length of the first cable (31) in the through-going passage (12), wherein at least a portion of the inner circumferential wall (15) is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage, and that the convex surface has a curvature away from the axial axis (B) of the through-going passage (12) wherein the radius of curvature (rc) of the convex surface is selected so that it equals an allowed bending radius of the first cable (31) to be accommodated in the through-going passage (12),

-the second bend guide structure (22) comprises a tubular part that is arranged with a second interfacing end portion for connection to the second housing end portion, wherein the second bend guide structure (22) has an inner circumferential wall (15) configured to form a through-going passage (12) with an inlet opening (13) and an outlet opening for receiving and accommodating a portion of the length of the first cable (31) in the through-going passage (12), wherein at least a portion of the inner circumferential wall (15) is arranged as a convex surface for restricting the bending of the cable accommodated in the through-going passage, and that the convex surface has a curvature away from the axial axis (B) of the through-going passage (12) wherein the radius of curvature (rc) of the convex surface is selected so that it equals an allowed bending radius (BR) of the second cable (32) to be accommodated in the through-going passage (12), wherein the allowed bending radius of the first cable (31) and/or the second cable (32) to be to be accommodated in the through-going passage (12) is within the range of 0.5-7.5m..

12. Field joint arrangement for subsea in accordance with claim 11, wherein the allowed bending radius of the first cable (31) and/or the second cable (32) to be to be accommodated in the through-going passage (12) comprises the minimum bending radius of the first cable (31) and the second cable (32) respectively.