GB2155195A

GB2155195A - Anchoring light weight submarine cable

Info

Publication number: GB2155195A
Application number: GB08404968A
Authority: GB
Inventors: Ronald Charles Oldham
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1984-02-25
Filing date: 1984-02-25
Publication date: 1985-09-18
Also published as: JPS60234417A; DK82785D0; GB8404968D0; FR2560455A1; FR2560455B1; US4621167A; DK82785A; GB2155195B

Description

1 GB 2 155 195 A 1

SPECIFICATION

Anchoring lightweight submarine cable This invention relates to anchoring a lightweight submarine cable to repeater housing, particularly for terminated lightweight f ibre optic submarine cables.

Present day submarine telecommunications cables fall into two categories. The first category is a generally lightweight cable comprising a central conductor, which may be a fibre optic conductor, surrounded by a high tensile strength member for taking the tensile loads which the cable has to bear, an electrical conductor to supply power to the repeaters, and a dielectric sheath in order to insulate the electrical conductor from the surrounding water. The second type of cable is similar to the lightweight type just described, except that it has an outer armouring layer or layers to protect the cable f rom chafing and from trawler and anchor damage.

The first type of cable, the lightweight cable, is used in deep water applications where the likelihood of damage from chafing and anchors is negligible. The second type of cable is used in shallow water and landfall applications where the likelihood of damage from chafing, fishing vessels and anchors, is high.

Connecting the second type of cable to a repeater housing poses little problem because the armour wires can be used to effect the connection. The first type of cable poses greater difficulty and it has been our practice in the past to armour the end portion of the cable so that for all intents and purposes it is similar to the armoured cable for the purposes of connecting itto the repeater housing.

The application of armour wires to the end portion of a lightweight cable is an expensive and time consuming task, requiring as it does, passing the lightweight cable through a conventional armouring machine for a very short run.

It is an object of the present invention to provide a simplified cable anchorage which is inexpensive yet effective for anchoring a submarine cable end to a repeater housing.

According to the present invention there is pro- vided a method of securing a terminated submarine cable to a repeater housing comprising snapping helically-preformed high tensile anchorwires onto the joint portion of the termination and an adjoining portion of the cable, there being a pressure resisting collar beneath the armour wires at the end of the cable, clamping the end of the preformed armour wires between an external clamping arrangement secured to the repeater housing and the internal pressure resisting collar, and clamping the armour wires towards the other end onto the submarine cable.

Conveniently the preformed wires can be formed singularly and snapped individually onto the termin ated cable, or they can be glued into subsets in groups of three or four and then assembled around the cable mutually conforming as to hand of lay, internal helical diameter and pitch length. Preferably the external clamping arrangement comprises the parallel internal fitting grip collar to provide the 130 internal pressure resisting core, and parallel-bored external-tapered segments which are clamped against a plate so that the conical taper drives the segments inwardly to clamp the armour wires.

The armour wires are strapped at their other ends around the cable with wire binders or stainless steel strapping, to clamp them to the cable.

As an alternative the preformed armour wires may be formed complete around a mandrel, then taken off in groups of three or four and glued together into subsets.

The armour wires are preferably coated with a vinyl synthetic adhesive and can be dusted with grit.

In order that the invention can be clearly under- stood reference will now be made to the accompanying drawings in which:

Figure 1 shows a single preformed armour wire for use in terminating a submarine optical fibre cable according to a first embodiment of the invention, Figure 2 shows a subset of armour wires each similar to Figure 1 and glued together, Figure 3 shows the armour wires of Figure 1 or Figure 2 applied to a terminated lightweight submarine optical fibre cable according to an embodi- ment of the present invention, and Figure 4 shows part of Figure 3 on a larger scale.

Referring to Figure 1 the preformed armour wire comprises a vinyl synthetic adhesive coated high tensile steel wire 1 which has a helical pitch of about 18 inches and an internal helix diameter slightly less than the outer dianneter of the terminated cable 2 shown in Figure 3.

Referring to Figure 2 there is shown a subset of armour wires 3 each as shown in Figure 1 but glued together with a synthetic resin. These wires are glued in subsets of three or four and can either be formed singularly such as the one shown in Figure 1 or can be formed complete around a mandrel (not shown) and then taken off in groups of three or four and subsequently glued together with a vinyl synthetic adhesive (GRIPSOTITE XN1 9) and dusted with aluminium oxide or carbon grit of e.g. Grade 100.

Referring to Figure 3 a terminated cable 2 is terminated to a smaller diameter tail cable 4 at a joint extending over the length 5. Around tail cable 4 is a helical spring 6 which supports the armour wires over the tail cable and allows tail cable bending over the end portion. At the very end a parallel sided internal fitting grip collar 7 is secured to the spring 6.

This resists the radial clamping pressure of the seg m ents 11.

The spring 6 is located at one end on a spigot 6A which has a tapered interior 6B to fit over the tapered end of the termination 5, and at the other end on a spigot 7A of the collar 7 (see Figure 4).

The collar 7 has a threaded end 713 so it can be passed through a hole in the anchor plate 9 and be locked thereto with a nut 7C.

Preformed anchor wires such as shown in Figure 1 or Figure 2 are snapped around the cable 2 and are indicated generally by the reference numeral 8. A plate 9 schematically represents a mounting plate at the end of a submersible repeater housing and the ends 10 of the armour wires are clamped between parallel bored externally tapered segments 11 and 2 GB 2 155 195 A 2 an internally conically tapered clampring 12. The clampring 12 is drawn towards the plate 9 by bolts such as 13, so that the tapered segments 11 tightly grip the ends of the preformed armour wires against 5 the fitting grip collar 7.

At the other end of the armour wires are wire binders or stainless steel strappings 14 which clamp the wires to the cable.

The anchor wires have a length in the range eighteen to twenty five feet and are helically formed with a helix having an internal diameter such as to be capable of being wrapped around the cable and with an open pitch of about eighteen inches and sufficieritto enable the wire to be wrapped around the cable from the side without exceeding the elastic limit of the wire.

As can be seen the anchoring arrangement described is simple and yet we have found effective in terminating a lightweight submarine cable to a repeater housing.

Claims

1. A method of securing a terminated submarine cable to a repeater housing comprising snapping helical ly-preformed high tensile anchor wires onto the joint portion of the termination and an adjoining portion of the cable, there being a pressure resisting collar beneath the armour wires at the end of the cable, clamping the end of the preformed armour wires between an external clamping arrangement secured to the repeater housing and the internal pressure resisting collar, and clamping the armour wires towards the other end onto the submarine cable.

2. A method as claimed in claim 1, wherein the preformed wires are individually assembled onto the cable.

3. A method as claimed in claim 1, wherein sets of the preformed wires are bonded together and applied as a set to the cable.

4. A method as claimed in any preceding claim, wherein the armour wires are coated with adhesive which holds grit to improve the grip of the armour wires.

5. A method substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. A terminated submarine cable secured by a method as claimed in any preceding claim.

7. A secured, terminated submarine cable substantialiy as hereinbefore described with reference to and as illustrated in Figure 3 of the accompanying drawings.

Printed in the U K for HMSO, D8818935,7185,7102. Published byThe Patent Office, 25 Southampton Buildings, London, WC2A lAYfrom which copies may be obtained.