Patent Application
20160126708
The present invention relates to methods of protecting a cable or cables, methods of repairing a cable or cables, to a sleeve, to a cable or cables in combination with a sleeve, and to a dispenser for a sleeve.
Cables have multifarious uses, including carrying electrical current, transmitting light, or just applying a tensile force. It is generally desirable in many instances to protect the cable from damage or the environment. Many cables are manufactured to incorporate a protective layer, e.g. electrical cables may have a plastic coating which protects and insulates the conductive elements. However, it may be desirable to apply further protection after the point of manufacture to protect or repair one cable or more cables by applying a protective sleeve around the outside of the cable or cables. This can be used for example to protect the cable from abrasion, impact, provide electrical, thermal or other insulation, or just to secure multiple cables together. Moreover, it may be desirable to apply the sleeve to the cable at the point where the cable is in end use or after it is assembled as part of a larger apparatus. The problem arises of how to apply the sleeve to the cable, particularly in the case where the cable is particularly long or the cable is inaccessible in use. It is also generally desirable for the sleeve to be securely applied to the cable so that it stays in place during normal use of the cable. It is also desirable in some instances the cable to bend with the sleeve applied during normal use of the cable.
Some known schemes include winding a strip in a spiral around the cable or feeding the cable through shrink wrap tubing before shrinking the tubing to the cable.
In other known examples, it is known to apply a slit tube sleeve to the cable, passing the cable through the slit in the sleeve. Such sleeves are typically made from a polymer, which gives enough flexibility to allow the sleeve to open to receive the cable. Interlocking of the edges may be used to help secure the sleeve on the cable.
The present invention aims to provide improved ways of protecting or repairing a cable or cables.
According to a first aspect of the present invention, there is provided a method of protecting a cable or cables, the method comprising:
uncoiling a protective sleeve and forming the sleeve around a length of the cable or cables, wherein the sleeve comprises a fibre-reinforced composite body which has an extended form in which it is resiliently biased in the form of an elongate tube having a slit along its length by which the sleeve can be opened to receive the cable or cables so that the sleeve self forms around the cable or cables due to its resilience, wherein when coiled the sleeve is opened out at the slit to assume a flattened cross section.
The use of fibre reinforces composite sleeve allow the properties of the sleeve to be manipulated to “self form” around the cable or cables due to its resiliency in the slit tube shape. Preferably, the sleeve has an appropriate hoop modulus such that it naturally forms a tube that generally matches the shape of the underlying cable or cables. At the same time, the sleeve can be given flexibility in the longitudinal direction allowing the sleeve to bend sufficiently according to the preferred implementation with the allowable bending of the cable. The sleeve is opened at the slit to allow cable to pass through the gap. This means that the sleeve can be applied without passing it over the end of the cable which is an important advantage where the ends of the cable are difficult to access. Thus, the sleeve can securely stay in place on the cable, possibly with the help of a mastic or adhesive applied between the cable and sleeve. At the same time, when not applied to the cable, the sleeve can be opened out at the slit until flat or relatively flat and wound about an axis extending transversely to the longitudinal extent of the member, allowing the sleeve to be coiled for storage, transportation, etc. This is particularly advantageous for long lengths of cable where a single long length of sleeve can be used to protect the cable, which can still have a much smaller volume initially in its coiled form. In embodiments, the length of the sleeve when extended can be greater than 10 m, or 100 m, or more.
This arrangement is superior to prior art sleeves made for example from a polymer because these lack the structural properties achieved by use of fibre reinforced composites, which allow the sleeve to both be coiled and to self form around the cable. A polymer sleeve for example suffers from creep, meaning that if the sleeve were opened out and coiled, it would effectively end up being flat or at least loose its slit tube shape and therefore lose its effectiveness in self forming around a cable.
In various embodiments, the cable can take many different forms. The cable may be a wire rope or other tensile element, which is used, for example, for lifting, hauling, and towing or conveying force through tension. Alternatively or additionally, the cable may be are used to carry electric currents via one or more electrical conductor elements. Alternatively or additionally, the cable may be an optical cable containing one or more optical fibres in a protective jacket that supports the fibres. The sleeve may be used to bundle together several individual cables. The sleeve can be applied to cables of varying sizes and carrying capacities, e.g. to bundle together cables of domestic electrical appliances, or to form a protective sheath over high voltage power cables used to deliver electricity across large distances.
In an embodiment, the method comprising: progressively uncoiling the sleeve and forming it along the length of the cable or cables. Thus, the sleeve can be compactly stored and transported to where it is to be applied to a cable, at which point it can be progressively unwound and applied along the cable.
Preferably the fibre-reinforced composite comprises fibres that are aligned to achieve the resiliently biased form in the shape of a slit tube. By giving an appropriate alignment and positioning to the fibres when manufacturing the sleeve, the properties of the sleeve can be carefully controlled to suit the intended application. In particular, the hoop and tensile modulus of the sleeve can be selected to control the properties of the sleeve when applied to the cable, for example to allow the sleeve to self form around the cable and stay in place, and in embodiments to also allow a degree of bending of the cable and/or provide resistance to bending to the cable.
In an embodiment, the sleeve is a bistable member, having a first stable form in said slit tube shape, and a second stable form in which it is coiled. The bistable member has a stable form when coiled, meaning that it is easier and safer to keep the sleeve in its coiled form. Otherwise, the tendency of the sleeve might be to spontaneously uncoil, requiring some form of housing to prevent this.
Preferably the sleeve provides any one or combination of:
impact resistance; and
protection from ice accumulation to the cable or cables.
Preferably the sleeve has sufficient hoop modulus to self form around the cable or cables. The sleeve may have sufficient longitudinal modulus to form to the cable or cables whilst the cable or cables bends. As will be appreciated, the degree of bending required depends on what the cable is to be used for. The properties of the sleeve can be selected in accordance.
The method may comprise applying a mastic or adhesive to bond the sleeve to the cable or cables and/or bond together the longitudinal edges of the slit tube. This can help retain the sleeve in place on a cable. This can allow a higher degree of bending of the cable without the sleeve detaching from the cable than would be possible due to the hoop modulus of the sleeve alone.
In an embodiment, at least one pocket of mastic or adhesive is attached to the inner surface of the sleeve, the method comprising applying pressure to the outer surface of the sleeve when applied to the cable or cables such that the pocket ruptures and delivers mastic or adhesive to a selected area. This provides a convenient way of applying the mastic or adhesive to the required areas.
The pocket may have at least one weak portion in a predetermined location that is designed to rupture when the pressure is applied, so as to control the location in which the mastic or adhesive is applied. This can allow for example one or more pockets to evenly distribute mastic or adhesive in the space all around the sleeve between the sleeve and cable.
The method may comprise applying a filler between the sleeve and the cable or cables where the density of the filler is chosen to achieve a predetermined buoyancy of the cable or cables and the sleeve. In marine or aquatic applications, this may be beneficial in helping control the position of the cable or cables.
In an embodiment, the longitudinal edges of the slit tube overlap. One or more pockets of adhesive may be used to seal the overlapping edges.
In an embodiment, the method comprises controlling the bend radius of the cable or cables under an expected load by applying a sleeve having predetermined bending stiffness to a portion of the cable or cables.
A second sleeve may be applied over a first portion of the first sleeve but not over a second portion of the first sleeve so that the bend radius of the cable or cables under the first portion is different from the bend radius of the cable or cables under the second portion under a bending load.
According to a second aspect of the present invention, there is provided a method of repairing a cable or cables, comprising applying a sleeve to a cable or cables according to any preceding claim over a damaged area.
In embodiments, the sleeve is applied to the cable or cables whilst the cable or cables is deployed.
In an embodiment the cable or cables is a marine seismic data acquisition cable. The sleeve may be applied to the cable or cables aboard a marine vessel. Thus, the marine cable can be repaired in situ, obviating downtime in removing cables for repair. The cable or cables may be spooled between two drums, wherein the sleeve is applied to the length of cable or cables extending between the drums. This provides a convenient way of applying the sleeve to a length of cable in situ.
The method may comprise applying the sleeve to the cable or cables using a dispenser, the dispenser comprising a support structure and a reel attached to the support structure about which the sleeve in its flat form is wound, wherein using the dispenser comprises progressively unwinding the sleeve from the reel and applying it to the cable or cables. The dispenser may comprise a guide device attached to the support structure arranged to apply pressure to the outside of the sleeve when applied to the cable or cables in order to rupture the pockets of mastic or adhesive.
According to a third aspect of the present invention, there is provided a cable or cables having a protective sleeve formed around a length of the cable or cables, wherein the sleeve comprises a fibre-reinforced composite body which has an extended form in which it is resiliently biased in the form of an elongate tube having a slit along its length by which the sleeve can be opened to receive the cable or cables so that the sleeve self forms around the cable or cables due to its resilience, wherein the sleeve can be opened out at the slit to assume a flattened cross section so that it can be coiled when not applied to the cable or cables.
According to a fourth aspect of the present invention, there is provided a sleeve comprising a fibre-reinforced composite body which has an extended form in which it is resiliently biased in the form of an elongate tube having a slit along its length by which the sleeve can be opened to receive the cable or cables so that the sleeve self forms around the cable or cables due to its resilience, wherein the sleeve can be opened out at the slit to assume a flattened cross section so that it can be coiled when not applied to the structure,
wherein the sleeve has at least one pocket attached to its inner surface, wherein the pocket contains mastic or adhesive, and wherein application of pressure to the outside of the sleeve when applied to the structure causes the pocket to burst so as to apply mastic or adhesive between the sleeve and cables and/or between two overlapping edges of the sleeve.
The dispenser may comprise a reel and a guide device attached to support structure, wherein the sleeve is disposed when coiled about the reel, wherein using the dispenser comprises progressively uncoiling the sleeve from the reel and applying it to the cable or cables.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:
The sleeve 1 comprises a fibre-reinforced composite body having a stable form in the shape of an elongate slit tube so as to self form around the cable. The sleeve 1 can be opened out to be substantially flat so that it can be coiled when not applied to the cable or cables.
Use of a fibre-reinforced composite means that the structural properties can be manipulated so that the sleeve is adapted to both self form around a cable and to be opened out flat when coiled. The fibre-reinforced composite comprises fibres which may be positioned and aligned so as to achieve a stable form in the shape of a slit tube. The sleeve 1 has sufficient hoop modulus to self form around the cable. The sleeve 1 preferably has sufficient longitudinal modulus to form to the cable whilst the cable bends to allow the expected bending range of the cable in use. Preferably the sleeve can self form to the cable whilst allowing a radius of bending of 10d, or more preferably 5d, or less, where d is the diameter of the slit tube in the bending direction.
The sleeve 1 may be a bistable member, having a first stable form in an extended form in which it has said slit tube shape, and a second stable form in which it is longitudinally curved having a flat cross section so that it can be coiled. Examples of bistable coilable members are disclosed in the Applicant's U.S. Pat. No. 6,217,975 the entire contents of which are hereby incorporated by reference. Conventional methods can be used to make the composite or bistable member. Advantageous mechanised production methods of making a composite member are disclosed in the Applicant's GB1301637.3 filed 30 Jan. 2013. Using a bistable member in this way means that the coiled sleeve is stable, meaning that it is easier to handle and store, etc.
Preferably, the sleeve 1 provides any one or combination of electrical insulation, abrasion resistance, impact resistance and protection from ice accumulation to the cable or cables, or just helps secure together a bundle of cables 10 to protect against tangling etc. The sleeve 1 may also protect the cable 10 from corrosion and may preferably be corrosion resistant itself.
The sleeve 1 can also allow areas of damage 13 to the protective layer 12 to be repaired.
Alternatively or additionally the sleeve 1 can incorporate an attachment element allowing the cable 10 to be attached at that point.
As shown in
In the case where the cable 10 has a damaged outer layer/coating, the sleeve 1 can be used to protect against ingress of water or other fluids that might migrate along the cable through the damaged section.
One example where it is beneficial to protect a cable 10 is in marine seismic data acquisition cable systems. Seismic vessels 51 are ships that are solely used for the purpose of seismic survey in the high seas and oceans. A seismic vessel 51 is used as a survey vessel for the purpose of pinpointing and locating the best possible area for oil drilling in the middle of the oceans. Traditional marine seismic surveys are conducted using specially-equipped vessels 51 that tow one or more cables 52 containing a series of hydrophones 53 at constant intervals (see
These seismic survey cables 52 typically consist of hundreds of strands of wire and tens of fibre optic strands encased in a plastic coating. The plastic coating is prone to damage when deployed and when being reeled onto and off of storage drums 56 at the back of the boat. The cables 52 are currently impractical to repair in the field. As a result, the cables 52 are either shipped back to the manufacturers for repair, which leads to the survey vessel being out of use for a significant period, or else the cables 52 are simply used to destruction and then discarded.
In the present embodiment, a sleeve 1 according to the present invention can be used to repair the cable 52 in the field. Coiled sleeves 1 can be stored on the vessel 51 until needed. When a cable 52 gets damaged, the sleeve 1 can be applied to the damaged section of cable 52. A mastic or adhesive can be applied between the cable and sleeve 1 or between the edges of the sleeve to join the slit in the tube. This can help secure the sleeve 1 to the cable 10.
Typically the cables 52 are oily/dirty and do not lend themselves well to adhesion. Nonetheless, applying mastic means sufficient friction is built up between the cable 52 and the mastic to prevent the sleeve 1 from moving during deployment or when wound on the drum 56.
The sleeve 1 can be applied as the cable 52 is wound on or off of the drum 56 at the back of the vessel 51 to a damaged section as shown in
Thus, the sleeve 1 repairs the damaged section of cable 52 whilst giving sufficient flexibility to allow the cable to be wound on to the drum. The sleeve 1 may be stored in a coiled form until needed, and may be applied progressively along the damaged length of cable 52. This much simplifies repairing the cable 52 in the field, or when transported back to a manufacturing/repair facility.
A dispenser 100 may be provided to help dispense and apply the sleeve 1. As shown in
Additionally or alternatively, the dispenser 100 has a guide device 110 arranged to guide the sleeve 1 and help form the sleeve 1 around the cable 10 as it unwinds. The guide device 110 may also be mounted to the housing or support structure. In the example of
The sleeve 1 may have pockets 115 of mastic or adhesive or similar bonding or filling substances disposed at desired positions around their inner surface. When the sleeve is formed around the cable 10 and pressure is applied to the sleeve 1, the pockets rupture, releasing the mastic or adhesive between the sleeve 1 and the cable, thereby bonding or filling the gap between the sleeve 1 and cable 10. The guide features of the guide device 110, e.g. the end profile 111a or rollers 112, may be arranged to compress the sleeve 1 against the cable 10 so as to burst the pockets 115. Alternatively, this could be performed manually or via a separate tool.
As will be appreciated, the number and positioning of the pockets 115 and or the way in which the pockets 115 are arranged to rupture can be selected in advance to control the way in which the mastic or adhesive is required to fill the void between the sleeve and cable 10. For example, as shown in
As shown by
Many different arrangements of pocket 18 and methods of applying the sleeve to rupture the pockets 18 can be used according to the application.
One or more sleeves 1 can also be used to provide strain relief or bending control to a cable 10. In the example shown by
Thus, by layering plural sleeves 1 along the cable 10, the degree of bending along the cable can be controlled so that the minimum bend radius is not reached. By controlling the size and positioning of the various layers of sleeves 1a,1b, the bending stiffness along the cable 10 and thus the bending radius under selected operating conditions can be controlled as desired using sleeves 1a,1b that themselves are homogenous in their bending stiffness along their length.
Embodiments of the present invention have been described with particular reference to the example illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1310141.5 | Jun 2013 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2014/051731 | 6/4/2014 | WO | 00 |
