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GB2101392A - An electric and/or optical cable - Google Patents

An electric and/or optical cable Download PDF

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Publication number
GB2101392A
GB2101392A GB08211727A GB8211727A GB2101392A GB 2101392 A GB2101392 A GB 2101392A GB 08211727 A GB08211727 A GB 08211727A GB 8211727 A GB8211727 A GB 8211727A GB 2101392 A GB2101392 A GB 2101392A
Authority
GB
United Kingdom
Prior art keywords
electric
tape
plastics
metal
cable
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08211727A
Other versions
GB2101392B (en
Inventor
Godfrey Reginald Morgan Dench
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balfour Beatty PLC
Original Assignee
BICC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BICC PLC filed Critical BICC PLC
Priority to GB08211727A priority Critical patent/GB2101392B/en
Publication of GB2101392A publication Critical patent/GB2101392A/en
Application granted granted Critical
Publication of GB2101392B publication Critical patent/GB2101392B/en
Expired legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B9/00Power cables
    • H01B9/005Power cables including optical transmission elements
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00Insulated conductors or cables characterised by their form
    • H01B7/17Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • H01B7/2825Preventing penetration of fluid, e.g. water or humidity, into conductor or cable using a water impermeable sheath
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B9/00Power cables
    • H01B9/02Power cables with screens or conductive layers, e.g. for avoiding large potential gradients

Landscapes

  • Insulated Conductors (AREA)

Abstract

In an electric and/or optical cable for use suspended under water at depths of at least 1,000m, a stranded conductor 11 is surrounded by a water-impermeable barrier comprising a cushioning layer 15 of elastomeric material e.g. non-vulcanised butyl rubber, a longitudinally applied, transversely folded copper tape 17 carrying a polyethylene coating 18 and, bonded to the coating, a high density polyethylene sheath 20. The tape 17 has a helically extending corrugation formed by winding around the tape a plastics coated polyethylene terephthalate filament 19 which is applied under such a tension as to corrugate the tape, the plastics coating on the filament being bonded to the sheath 20. The cores 2 are laid up around a tensile member 1 comprising polyamide filaments 6 using two cores per phase. The assembly of cores 2 is surrounded by helically wound tin-bronze tape 3 and helically lapped polypropylene tape 4. Semiconductive screening layers 12, 14 may be provided and the tape may have a polyester layer 16 bonded to layer 15. <IMAGE>

Description

SPECIFICATION An improved electric and/or optical cable This invention relates to electric and/or optical cables and more particularly to waterproof electric and/or optical cables for use under water or in any other location in which entry of water or moisture into the interior of the cable might occur if the cable were not rendered waterproof.
It is common practice to render waterproof an electric cable that is to be installed under water by enclosing the cable within an extruded sheath of metal or metal alloy that is suitably protected against corrosion. However, where it is required to suspend an electric cable under water under its own weight substantially vertically or in a catenary curve, e.g. when feeding an oil or gas production facility on the seabed at a depth of several hundreds of metres, the cable must be of such a construction that, not only must it be able to withstand an external water pressure which might be in the region of one hundred bar, but, whilst in service, it must also be capable of withstanding many millions of flexing cycles caused by the heavy water currents to which the cable will be subjected when suspended at such water depths.Under such conditions an electric cable with an extruded metal sheath is unable to withstand the many millions of flexing cycles to which it will be subjected and, consequently, a metal sheathed electric cable is not suitable for feeding an oil or gas production facility located on the seabed at a depth of several hundreds of metres.
It is an object of the present invention to provide an improved electric and/or optical cable which is suitable for use when suspended under water at depths of at least 1000 metres and which, during its service life at such depths, is capable of withstanding at least several million flexing cycles.
According to the invention, the improved electric and/or optical cable comprises at least one electric and/or optical cable core, and, surrounding the core or assembly of cores, a water-impermeable barrier comprising a cushioning layer of elastomeric material; a substantially circumferentially continuous wall of metal or metal alloy constituted by at least one longitudinally applied, transversely folded metal tape which carries a coating of plastics material on its outwardly facing surface, the metal having mutually spaced circumferential corrugations or at least one helically extending corrugation throughout its length and the metal wall so overlying the cushioning layer that elastomeric material fills the trough or troughs of the corrugation or corrugations in the inner surface of the metal wall; and, surrounding the metal wall, an extruded sheath of plastics material which is bonded to the plastics coating on the outer surface of the metal tape or tapes constituting the metal wall.
Preferably, the or each metal tape constituting the metal wall also carries a coating of plastics material on its inwardly facing surface and, preferably also, this plastics coating is bonded to the elastomeric material constituting the cushioning layer.
The mutually spaced circumferential corrugations or the or each helically extending corrugation in the metal wall may be formed after the or each metal tape has been longitudinally applied to and transversely folded around the cushioning layer and in such a way that elastomeric material of the cushioning layer is caused to flow into the troughs of the corrugations or the trough of the or each corrugation, or the or each longitudinally applied, transversely folded metal tape may be corrugated before it is applied to the cushioning layer, the tape being transversely folded around the cushioning layer so tightly that elastomeric material is caused to flow into the trough or troughs.Preferably, however, after the or each metal tape has been longitudinally applied to and transversely folded around the cushioning layer, at least one elongate flexible binder is helically wound around the metal wall under such a tension that the metal wall is deformed to form a helically extending corrugation or helically extending corrugations throughout the length of the cable and that elastomeric material of the cushioning layer is caused to flow into and to fil! the trough of the or each helical corrugation. At least the outer surface of the or each flexible binder preferably is of plastics material and preferably, also, the plastics material of the overlying sheath bonds not only to the plastics coating on the outer surface of the or each metal tape but also to the plastics surface of the or each flexible binder.The or each flexible binder may be a plastics coated wire or strand, a bare wire or strand, or a plastics coated non-metallic filament, e.g. filament of terylene or an aromatic polyamide, such as that sold under the Trade Mark "Kevlar".
The or each metal tape forming the metal wall is preferably of copper or a copper-based alloy or of aluminium or an aluminuum-based alloy.
Where the cable of the present invention is an electric cable, it may be an electric power cable and, in this case, the core may be a single stranded electric conductor. Alternatively, the cable may be a telecommunications cable and, in this case, the core may be a multiplicity of plastics insulated conductors. Where the cable of the present invention is an optical cable, the core may be an extruded elongate body of plastics material having a bore in which a separate optical fibre and/or an optical bundle is loosely housed or the core may be at least two plastics tubes assembled together in at least one of which tubes at least one separate optical fibre and/or at least one optical bundle is loosely housed. The cable of the present invention may be a combination of any two or more of an electric power cable, a pilot or communication cable and an optical cable.
A single core electric power cable in accordance with the present invention may also constitute one core of a multi-core electric power cable.
The water-impermeable barrier of the improved electric and/or optical cable of the present invention provides the important advantage that it will withstand heat cycling under service conditions more satisfactorily than other forms of water-impermeable barrier hitherto proposed and used.
The invention will be further illustrated by a description, by way of example, of a preferred 11 KV multi-core electric power cable for suspension under water under its own weight in a caternary curve with reference to the accompanying diagrammatic drawing which shows a transverse cross-sectional view of the cable.
Referring to the drawing, the cable comprises a central flexible tensile member 1, six cores 2 laid helically around the central tensile member and, surrounding the cores, a binding layer 3 of helically wound tape of tin-bronze, the direction of lay of the tape being opposite to that of the helically laid cores, and a serving layer 4 of helically lapped tape of polypropylene, the direction of lay of the serving layer being opposite to that of the binding layer.
The central tensile member 1 comprises a multiplicity of filaments 6 of Kevlar, which filaments all lie substantially parallel to the axis of the cable and, surrounding the multiplicity of filaments, a sheath 7 of the polyethylene The six cores 2 are arranged two cores per phase and each core comprises a flexible stranded conductor 1 a conductor screen 1 2 comprising a layer of semi-conducting tape and an extruded layer of semi-conducting cross-linked polyethylene; a dielectric wall 1 3 comprising an extruded layer of cross-linked polyethylene; a dielectric screen 14 comprising an extruded layer of semi-conducting cross-linked polyethylene; a cushioning layer 15 of the non-vulcanised butyl rubber; a water-impermeable barrier comprising a longitudinally applied transversely folded copper tape 1 7 having on its inner surface a coating 16 of polyester which is bonded to the cushioning layer 1 5 and having on its outer surface a coating 1 8 of polyethylene; a plastics coated terylene filament 1 9 helically wound around the polythene-coated copper tape 1 7 under such tension as to form in the water-impermeable barrier a helical corrugation, the helical trough on the inner surface of the barrier being filled with non-vulcanised butyl rubber; and, overlying and bonded to the polyethylene coating 1 8 and to the plastics coated terylene filament 19, an extruded overall sheath 20 of high density polyethylene.
The cable illustrated in the drawing, when suspended under water in a catenary curve to a depth of 1 000m, is capable of withstanding an external water pressure of 100 bar and at least several million flexing cycles. In addition, the central tensile member takes substantially all the tensile load to which the suspended cable will be subjected so that there is negligible risk that the suspended cable will twist or become tangled.
Terylene is a registered Trade Mark.

Claims (13)

Claims
1. An electric and/or optical cable comprising at least one electric and/or optical cable core and, surrounding the core or assembly of cores, a water-impermeable barrier comprising a cushioning layer of elastomeric material; a substantially circumferentially continuous wall of metal or metal alloy constituted by at least one longitudinally applied, transversely folded metal tape which carries a coating of plastics material on its outwardly facing surface, the metal wall having mutually spaced circumferential corrugations or at least one helically extending corrugation throughout its length and the metal wall so overlying the cushioning layer that elastomeric material fills the trough or troughs of the corrugation or corrugations in the inner surface of the metal wall; and, surrounding the metal wall, an extruded sheath of plastics material which is bonded to the plastics coating on the outer surface of the metal tape or tapes constituting the metal wall.
2. An electric and/or optical cable as claimed in Claim 1, wherein the or each metal tape constituting the metal wall also carries a coating of plastics material on its inwardly facing surface.
3. An electric and/or optical cable as claimed in Claim 2, wherein the plastics coating on the inwardly facing surface of the or each metal tape is bonded to the elastomeric material constituting the cushioning layer.
4. An electric and/or optical cable as claimed in any one of the preceding Claims, wherein at least one elongate flexible binder is helically wound around the metal wall under such a tension that the metal wall is deformed to form a helically extending corrugation or helically extending corrugations throughout the length of the cable and that elastomeric material of the cushioning layer is caused to flow into and to fill the trough of the or each helical corrugation.
5. An electric and/or optical cable as claimed in Claim 4, wherein at least the outer surface of the or each flexible binder is of plastics material and the plastics material of the overlying sheath bonds not only to the plastics coating on the outer surface of the or each metal tape but also to the plastics surface of the or each flexible binder.
6. An electric and/or optical cable as claimed in Claim 4 or 5, wherein the or each flexible binder is a plastics coated wire or strand, a bare wire or strand, or a plastics coated non-metallic filament.
7. An electric and/or optical cable as claimed in any one of the preceding Claims, wherein the or each metal tape forming the metal wall is of copper or a copper-based alloy or of aluminium or an aluminium-based alloy.
8. An electric cable as claimed in any one of the preceding Claims, wherein the core is a single stranded electric conductor.
9. An electric cable as claimed in any one of Claims 1 to 7, wherein the core is a multiplicity of plastics insulated conductors.
10. An optical cable as claimed in any one of Claims 1 to 7, wherein the core is an extruded elongate body of plastics material having a bore in which a separate optical fibre and/or an optical bundle is loosely housed.
11. An opticaLcable as claimed in any one of Claims 1 to 7, wherein the core is at least two plastics tubes assembled together in at least one of tubes which at least one separate optical fibre and/or at least one optical bundle is loosely housed;
1 2. A method of manufacturing an electric and/or optical cable as claimed in any one of Claims 1 to 3, wherein the mutually spaced circumferential corrugations or the or each helically extending corrugation in the metal wall is formed- after the or each metal tape has been longitudinally applied to and transversely folded around the cushioning layer and in such a way that eíastomeric material of the cushioning layer is caused to flow into the troughs of the corrugations or the trough of the or each corrugation.
13. A method as claimed in Claim 12, wherein at least one elongate flexible binder is helically wound around the metal wall under such a tension that the metal is deformed to form a helically extending corrugation or helically extending corrugations throughout the length of the cable and that elastomeric material of the cushioning layer is caused to flow into and to fill the trough of the or each helical corrugation.
1 4. A method of manufacturing an electric and/or optical cable as claimed in any one of Claims 1 to 3, wherein each longitudinally applied, transversely folded metal tape is corrugated before it is applied to the cushioning layer, the tape being transversely folded around the cushioning layer so tightly that elastomeric material is caused to flow into the trough or troughs.
1 5. An electric cable substantially as hereinbefore described with reference to and as shown in the accompanying drawing.
GB08211727A 1981-04-23 1982-04-22 An electric and/or optical cable Expired GB2101392B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08211727A GB2101392B (en) 1981-04-23 1982-04-22 An electric and/or optical cable

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8112561 1981-04-23
GB08211727A GB2101392B (en) 1981-04-23 1982-04-22 An electric and/or optical cable

Publications (2)

Publication Number Publication Date
GB2101392A true GB2101392A (en) 1983-01-12
GB2101392B GB2101392B (en) 1984-11-14

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Family Applications (1)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2550863A1 (en) * 1983-08-18 1985-02-22 Kokusai Denshin Denwa Co Ltd OPTICAL FIBER CABLE
GB2144878A (en) * 1983-08-05 1985-03-13 Bicc Plc Optical cables
US4652323A (en) * 1984-01-09 1987-03-24 Olin Corporation Plasma deposition applications for communication cables
EP0217066A3 (en) * 1985-08-30 1988-11-30 PIRELLI CAVI S.p.A. Optical fiber telecommunication cable
EP2750144A4 (en) * 2011-08-23 2015-03-04 Furukawa Electric Co Ltd SUBMARINE CABLE, MULTILAYER TAPE FOR A WATER SHIELDING LAYER OF A SUBMARINE CABLE, AND METHOD FOR IMPROVING FATIGUE CHARACTERISTICS OF A SUBMARINE CABLE
CN113113174A (en) * 2021-02-22 2021-07-13 深圳市壹电电力技术有限公司 Cable with fault self-diagnosis function for intelligent cable system

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2144878A (en) * 1983-08-05 1985-03-13 Bicc Plc Optical cables
FR2550863A1 (en) * 1983-08-18 1985-02-22 Kokusai Denshin Denwa Co Ltd OPTICAL FIBER CABLE
US4652323A (en) * 1984-01-09 1987-03-24 Olin Corporation Plasma deposition applications for communication cables
EP0217066A3 (en) * 1985-08-30 1988-11-30 PIRELLI CAVI S.p.A. Optical fiber telecommunication cable
EP2750144A4 (en) * 2011-08-23 2015-03-04 Furukawa Electric Co Ltd SUBMARINE CABLE, MULTILAYER TAPE FOR A WATER SHIELDING LAYER OF A SUBMARINE CABLE, AND METHOD FOR IMPROVING FATIGUE CHARACTERISTICS OF A SUBMARINE CABLE
US9006574B2 (en) 2011-08-23 2015-04-14 Furukawa Electric Co., Ltd. Undersea cable, multilayer tape for water shielding layer of undersea cable, and method for improving fatigue characteristics of undersea cable
CN113113174A (en) * 2021-02-22 2021-07-13 深圳市壹电电力技术有限公司 Cable with fault self-diagnosis function for intelligent cable system

Also Published As

Publication number Publication date
GB2101392B (en) 1984-11-14

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PCNP Patent ceased through non-payment of renewal fee