GB2138088A

GB2138088A - Submarine cable joint housing

Info

Publication number: GB2138088A
Application number: GB08310159A
Authority: GB
Inventors: Frank Richard Attenborough; Michael John Bryant
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1983-04-14
Filing date: 1983-04-14
Publication date: 1984-10-17
Also published as: GB8310159D0; NO841450L; FR2544562A1

Abstract

An armoured submarine cable joint comprising a tubular housing 10 with internally tapered end portions 10a closely fitting the outer sheath of the submarine cable 5 containing hydraulic hoses 1, 2 wherein the armouring wires 4 or tapes adjacent each cable end are splayed and deformed 4a within each tapered end portion, characterised in that the housing is fabricated from glass filament wound epoxy resin sections adhesively bonded together and potted with a filled epoxy resin system. <IMAGE>

Description

SPECIFICATION Submarine cable joint housing This invention relates to a housing assembly for submarine cable joints.

The term "cable" is used hereinafter to include electrical cables, fibre optic cables, hose bundles or any combinations thereof. For example a single cable may include hoses carrying hydraulic fluids, insulated metallic conductors for electric power requirements, and metallic conductors or optical fibres for communicating purposes. The cable also in cludes external armouring wires or tapes.

Such cables, and particularly joints in such cables, are required to withstand considerable longitudinal stresses when being laid in open sea conditions, or being lowered from oil rigs, whilst whist at the same time they must resist very high compressive forces when in situ at great depths.

Traditionally housing for submarine cable joints have been fabricated from machined steel tubes which incorporate (if required) steel armour anchorages, adjustable load col lars, threaded end caps, and are filled with filling compound after the joint has been made and the housing secured in place. The tensile load on the joint is transferred from the armouring via the load collars to the steel casing. The filling compound serves to pre vent any moisture entering the steel casing reaching the cable joints within the housing assembly. Such steel housings are expensive and heavy to handle.

According to the present invention there is provided a submarine cable joint housing comprising at least two housing end sections each formed as a hollow tube of filament wound epoxy resin composite, each end sec tion being formed with one internally tapered end portion with adjacent housing sections jointed together by bonded joints between non-tapering portions of the sections, at least one housing section being provided with a filler hole through which the completed hous ing is filled with a loaded epoxy resin filler compound.

The invention also provides a method of jointing an armoured submarine cable includ ing the steps of spreading and deforming the ends of the armouring wires or tapes adjacent each cable end, enclosing the cable joint within a tubular filament wound glass epoxy resin housing having internally tapered end portions closely fitting the external covering of the cable, and filling the housing with a loaded epoxy resin compound.

An embodiment of the invention will now be described with reference to the accom panying drawing which depicts a longitudinal section through one half of a submarine cable joint.

The cable to be joined is illustrated as a hydraulic hose bundle containing hoses 1, 2 encased in polyethylene belting which is in turn wrapped with steel armour wires 4.

Finally the armouring is covered by an outer polyethylene sheath 5.

Each cable end is threaded through a respective half of a filament wound glass epoxy resin housing section 10. The housing section is tubular in cross section, the main portion being of greater diameter internally then the external diameter of the cable outer sheath 5.

Each section has an internally tapered end portion 1 0a which is a close fit over the cable outer sheath 5.

To effect a cable joint each cable end is first threaded through a heat shrinkable sleeve 11, a synthetic resin bonded fibre (SRBF) annular plug 1 lea, an annular "U''-ring seal 1 lb. The housing section 10 is then slipped over the cable end. The outer sheath 5 is cut back to expose a length of armouring 4. The armour wires are splayed out and the ends 4a of the wires are randomly deformed, e.g. by kinking or joggling. Alternatively the wire ends may be left straight or just shot-blasted. The inner belting 3 is also cut back to a lesser extent to expose the individual hose ends 1,2. Each hose end is provided with a threaded coupling 12, 13 respectively. A metal stabilising sleeve 14 is forced over the inner belting 3 and a circular clamp 15 is attached thereto by screws 16.Compression of an annular seal ring 17 is effected between the sleeve and clamp flanges when the screws 16 are tightened. Lastly a heat shrink boot 18 may be placed over the end of the inner belting 3 and the clamp 15. The cable end is now ready for jointing to another similarly prepared cable end.

The two cable ends to be joined are brought together and the corresponding hose couplings 12. 13 screwed together. The respective housing sections 10 are then butted together after an internal joining sleeve 19 has been inserted into one housing section.

The housing sections are secured to each other and to the joining sleeve by adhesive bonded lap joint 10c, assisted by the butt joint 1 Ob. The SRBF plug 1 1 a is pushed into the machined recess in the housing end section, thereby compressing the "U"-ring seal 1 1 b. The heat shrinkable sleeve 11 is then moved into position over the plug and heated to form a tight shrink-fitted seal over the end of the housing and port of the cable. Alternatively the whole joint housing may be encased in a heat shrink covering.

When all of the above operations have been completed the interior of the housing is potted using a filled epoxy resin system via filler holes 1 Od in the housing sections 10, which act as a mould.

The result is a strong, lightweight cable joint that is pressure resistant and impervious to the ingress of moisture. Longitudinal tensile stress in the cable is transferred via the splayed and deformed armour wires to the epoxy resin filler within the tapered or conical end forms. Some of the stress is transferred further to the housing sections 10 and, via the bonded joint f Oc to the other end section, and thence back through the filler to the armour wires of the other cable end.

The fabrication of the housing end sections 10 is cheap compared with traditional steel housings. Each end section is easily fabricated on a removable mandrel, the only machining then required being to the joint areas to ensure good joints, and to the tapered extremity to provide a good fit for the "U"-ring seal.

The completed joint is very strong. Typical test figures for a joint on a 5 inch diameter cable with a housing of total length 48" show that it will withstand at least a 30 ton tensile stress.

As an alternative to a two part housing as shown in the drawing the housing can be made in, e.g. three parts. A central plain tubular section can be joined to two tapered end sections. Such a construction is shown in the figure with a machined overlap joint fOe between the central section and the tapered end section. This may be reinforced with a joining sleeve 1 8b if desired (shown in dotted outline only). This allows a versatile system to be built up with common end sections usable with a variety of different length central sections.

Whilst mention has been made of glass filament reinforcement of the epoxy resin composite, other filamentary materials are also available, e.g. KEVLAR (Reg. Trade Mark), carbon fibre, polyester etc. Also the lay angle of the filament can be different at different parts of the tube to provide required tensile/loop stress performance at difference positions.

CLAI MS: A submarine cable joint housing comprising at least two housing end sections each formed as a hollow tube filament wound epoxy resin composite, each end section being formed with one internally tapered end portion with adjacent housing sections jointed together by bonded joints between non-tapering portions of the sections, at least one housing section being provided with a filler hole through which the completed housing is filled with a loaded epoxy resin filler compound.

2. A joint housing according to claim 1 wherein two tapered end sections are combined with a central plain tubular section.

3. A joint housing according to claim 1 or 2, wherein the sections are jointed by means of machined overlap joints.

4. A joint housing according to claim 1 or 2, wherein the joints between the sections are provided with internal close fitting sleeves forming lap joints with the sections.

5. A joint housing according to any preceding claim wherein the epoxy resin composite is reinforced with a wound glass filament.

6. A submarine cable joint housing substantially as described with reference to the accompanying drawing.

7. A method of jointing an armoured submarine cable including the steps of spreading and deforming the ends of the armouring wires or tapes adjacent each cable end, enclosing the cable joint within a tubular filament wound epoxy resin housing having internally tapered end portions closely fitted the external covering of the cable, and filling the housing with a loaded epoxy resin compound.

8. A method of jointing an armoured submarine cable substantially as described with reference to the drawing.

9. An armoured submarine cable joint comprising a tubular housing with internally tapered end portions closely fitting the outer sheath of the submarine cable wherein the armouring wires or tapes adjacent each cable end are splayed and deformed within each tapered end portion, characterised in that the housing is fabricated from filament wound epoxy resin sections adhesively bonded together and potted with a loaded epoxy resin system.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

stress in the cable is transferred via the splayed and deformed armour wires to the epoxy resin filler within the tapered or conical end forms. Some of the stress is transferred further to the housing sections 10 and, via the bonded joint f Oc to the other end section, and thence back through the filler to the armour wires of the other cable end.

The fabrication of the housing end sections 10 is cheap compared with traditional steel housings. Each end section is easily fabricated on a removable mandrel, the only machining then required being to the joint areas to ensure good joints, and to the tapered extremity to provide a good fit for the "U"-ring seal.

The completed joint is very strong. Typical test figures for a joint on a 5 inch diameter cable with a housing of total length 48" show that it will withstand at least a 30 ton tensile stress.

As an alternative to a two part housing as shown in the drawing the housing can be made in, e.g. three parts. A central plain tubular section can be joined to two tapered end sections. Such a construction is shown in the figure with a machined overlap joint fOe between the central section and the tapered end section. This may be reinforced with a joining sleeve 1 8b if desired (shown in dotted outline only). This allows a versatile system to be built up with common end sections usable with a variety of different length central sections.

Whilst mention has been made of glass filament reinforcement of the epoxy resin composite, other filamentary materials are also available, e.g. KEVLAR (Reg. Trade Mark), carbon fibre, polyester etc. Also the lay angle of the filament can be different at different parts of the tube to provide required tensile/loop stress performance at difference positions.

CLAI MS: A submarine cable joint housing comprising at least two housing end sections each formed as a hollow tube filament wound epoxy resin composite, each end section being formed with one internally tapered end portion with adjacent housing sections jointed together by bonded joints between non-tapering portions of the sections, at least one housing section being provided with a filler hole through which the completed housing is filled with a loaded epoxy resin filler compound.
2. A joint housing according to claim 1 wherein two tapered end sections are combined with a central plain tubular section.
3. A joint housing according to claim 1 or 2, wherein the sections are jointed by means of machined overlap joints.
4. A joint housing according to claim 1 or 2, wherein the joints between the sections are provided with internal close fitting sleeves forming lap joints with the sections.
5. A joint housing according to any preceding claim wherein the epoxy resin composite is reinforced with a wound glass filament.
6. A submarine cable joint housing substantially as described with reference to the accompanying drawing.
7. A method of jointing an armoured submarine cable including the steps of spreading and deforming the ends of the armouring wires or tapes adjacent each cable end, enclosing the cable joint within a tubular filament wound epoxy resin housing having internally tapered end portions closely fitted the external covering of the cable, and filling the housing with a loaded epoxy resin compound.
8. A method of jointing an armoured submarine cable substantially as described with reference to the drawing.
9. An armoured submarine cable joint comprising a tubular housing with internally tapered end portions closely fitting the outer sheath of the submarine cable wherein the armouring wires or tapes adjacent each cable end are splayed and deformed within each tapered end portion, characterised in that the housing is fabricated from filament wound epoxy resin sections adhesively bonded together and potted with a loaded epoxy resin system.