WO2014177500A1

WO2014177500A1 - Electric flanged splice

Info

Publication number: WO2014177500A1
Application number: PCT/EP2014/058565
Authority: WO
Inventors: Olav Bakka; Ole A. Heggdal
Original assignee: Aker Subsea AS
Current assignee: Aker Solutions AS
Priority date: 2013-04-29
Filing date: 2014-04-28
Publication date: 2014-11-06
Anticipated expiration: 2015-10-29
Also published as: NO20130584A1

Abstract

This invention relates to a cable flange for providing sealed penetration for a cable through a water tight barrier, the flange comprising an opening having an inner part with essentially the same inner dimensions as the outer dimension of said cable, the flange inner part comprising a section extending a distance along the cable in a least one direction.

Description

ELECTRIC FLANGED SPLICE

The present invention relates to a cable passing through a sealed enclosure wall, especially a sea cable passing through a subsea enclosure wall, utilising one or two watertight flanges spliced onto the cable, for providing a method of simple, reliable connection of a cable to the electric equipment inside the enclosure. ELECTRIC FLANGED SPLICE

The present invention relates to a flange spliced onto a sea cable for providing a watertight assembly. The following description covers the simplest of the assemblies covered by the present invention. It is an object to the present invention to aim for simplicity. Complexity adds to possible sources of failure and is hence often less reliable then simple solutions. In this report simple solutions is called more reliable, however, simple solutions may have other failure mechanisms, which is considered.

Splicing of cable directly to the flange represents the present invention. Penetrators with flanges connecting the electric cable conductor in a penetrator on the outside of the enclosure represent known solutions. US4227043 illustrate as complicated solution for higher pressures incorporating additional sealing means. US2008/00173415 illustrates a fluid tight cable duct with connection for high pressure differences, thus not allowing the a cable to pass through. It is an object to the present invention to provide a simpler method for conducting the electric current through the enclosure wall then of known solutions. Known solutions utilise additional conductor connections (on each side of a penetrator) which represents a less reliable method then if the cable conductor is unbroken or spliced. It is also an object to the present invention to provide simpler methods then known insulation solutions. Penetrators utilise additional insulation pieces to insulate the conductor from earth (where conductor passes through the flange-wall and on each side of a penetrator), which represents a less reliable method then if the cable insulation is unbroken.

Thus it is an object to the present invention by splicing the cable to a flange to provide a simpler method of ensuring that any mechanical forces between the cable and the enclosure are not representing any risk.

It is also an object of the present invention to ensure that migration and diffusion processes of particles between the sea and the internals of the enclosure does not present a risk of insulation properties deterioration of insulating materials and fluids inside the enclosure. It is an additional object of the present invention to ensure that the cable is sufficiently water blocked in the longitude direction so that water cannot leak through or between any cable layer. The objects stated above are obtained with a cable penetration flange as described in the accompanying claims.

The technology design according to the invention is especially suitable for is for cables entering pressure balanced enclosures/ barriers, for example in applications related to cables or similar devices passing through a water tight wall or barrier where the pressure difference over the wall or barrier is low.

The invention will be described below with reference to the accompanying drawings, illustrating the invention by way of examples.

Figure 1 illustrates a first, preferred embodiment of the invention.

Figure 2 illustrates the cross section of the cable extending through the flange. Figure 3 illustrates a cross section of the flange shown in figure 1.

Figures 3a-c illustrates different embodiments of the flange sealing to the related

structure.

Figure 4 illustrates a cross section of a flange mounted on a cable.

Figure 5 illustrates an embodiment of the invention using two flanges and a pipe passing through a wall. Figure 6 illustrates an embodiment comprising an extension of the extended part of the flange.

Thus the invention as illustrated in figure 1 shows a conductor 1 having an insulation layer 2 and a outer sheath 4 passing through an opening in the flange body 11. The flange body has a tapered part 12 extending along the cable being provided with a tape or similar 21 fixing and sealing it against the flange body 11. The flange body is also fastened to a structure part 6 with bolts 18, where the structure may be part of a wall, hull etc. In the drawing the cable extends inside the structure in a tube or pipe 7 extending from the structure 6. The tape 21 will typically be placed on the side of the flange having the highest pressure to ensuring improved sealing.

As shown in figure 2 the insulation layer 2 may be constituted by a triple extruded inner semiconductor, insulation and outer semiconductor 2a and an insulation layer without semi conductors 2b as well as an outer sheath.

It is a supplementary object of the present invention to seal the layers and in between layers of the cable against longitude water migration or leak by utilising traditional splice components as done in industrial application. This applies for outer sheath, armours, screens, semiconductive layers, insulation layer(s) and conductor.

Figure 3 shows the flange body 11 more in detail. The spicing area 12 is shaped as an extension of the flange body 11 in the cable 1 direction having a thickness being rediced in the same direction. This way a tape 21 or similar may provide a gradual transition from the flange body to the cable. The tape material may be flexible so as to act as a gradual bend restrictor thus protecting the cable. This is illustrated more in detail in figure 4.

The flange body also is provided with a inner recess 13 with corresponding channel 15 to one of the flange sides in order to provide means for leak detection. The recess may include a block and bleed valve. The channel is shown as opening in the opposite side of the flange of the tape 21, but this may depend on the application and most suitable the environment for connecting devices to the channel 15. In addition the flange body may include metal or polymer O-rings 16 or similar sealing means in the contact area toward the structure 6, as well as bolt holes 17.

The flange body 11 can be shaped as traditionally used flanges except where it lays against the cable. The shape of the flange (the slope) where it lays against the cable (a shape that fits the splice) is an object of the present solution. It is an object of the present invention to simplify also the flange, by an alternative design where 2 or more (dependant on seal version) o-ring seals can be tested one by one without making use of any block and bleed valves.

Figures 3a-3c illustrates different types of connection to the structure 6 where figure 3a has sealing means encircling the cable where a metal seal (or 2 o-ring seals) placed on a cylinder face. In figure 3b two -o-ring seals on the face between the flanges. A combination of the sealings in figure 3a and 3b is also possible.

Figure 3 c illustrated an embodiment where the flange is welded to the structure 6.

Traditionally splice types are used. To use the traditional splice components to joint the flange to the cable is an object of the present invention. On figure 4 splice is applied on one side of the flange 11, preferably on the side being subject to the highest pressure. Dependant on access to do the splicing or casting one or two sides of the flange can be equipped with splice.

Figure 5 shows an additional embodiment of the invention for obtaining a

supplementary object of the present solution to enable using a second flanged splice. If the first seal for some reason do no function the second one will. In this case the first (and the second) spliced flange is welded by weld wl) to a pipe p) Pipe p) is welded to the enclosure wall by weld w2).

Another supplementary object of the present solution is to prevent long term water diffusion. A solution to this problem is illustrated in fig. 6. An oil filled hose hi) is fixed in one end to the flange f2). The hose hi) seals utilising a seal s4) against the cable outer sheath in the other end. Water migration in lognitudal direction will by this feature take significantly longer time then if no additional Water Migration Preventer is used.

Thus to summarize the invention relates to a cable flange for providing sealed penetration for a cable through a water tight barrier at small or no pressure differences between the different sides of the barrier. The flange comprises an opening having an inner part with essentially the same inner dimensions as the outer dimension of said cable, the flange inner part comprising a section extending a distance along the cable in a least one direction. The cable with insulation is thus allowed to extend unchanged through the splice

A sealing material, e.g. tape or casting, extends over said extended inner part and a chosen length of the cable extending through it so as to provide and improved sealing. The tape may also be flexible to provide an additional function as a bend restrictor. Preferably the extending inner part has a gradually reduced thickness along the cable direction from the flange to provide a gradual transition from the extending flange to the cable.

The flange may advantageously comprise a leakage test recess between the flange and the cable and a passage to at least one side of the flange comprising a block and bleed valve for connecting to measuring instruments on one side of the flange..

One embodiment of the invention the cable may be extending through a hose or pipe extending from said extended section along a predetermined length of the cable, the hose being sealed against said extended part in one end and the cable in the second end. This way leakage through the cable material may be limited by increasing the sealed length of the cable on one side of the flange. This may be advanateous when certain cables are used which may allow some migration of liquids into the material. A tape or similar may be applied to said extended section and first end of said hose for sealing said first end.

The flange according to the invention may be used in a system comprising a pipe or hose extending through a wall, where each end of said pipe or hose being connected to a cable flange according to the invention. The extending parts being oriented away from said hose thus sealing the inside of the pipe or hose from the environment of both sides The pipe is connected to each flange and may be welded or otherwise connected to the wall.

Claims

C l a i m s

1. Cable flange for providing sealed penetration for a cable through a water tight barrier at low pressure differences, the flange comprising an opening having an inner part with essentially the same inner dimensions as the outer dimension of said cable, the flange inner part comprising a section extending a distance along the cable in a least one direction, the cable with insulation thus extending .through the splice.

2. Cable flange according to claim 1, comprising a sealing material, e.g. tape or casting, extending over said inner part and a chosen length of the cable extending therethrough.

3. Cable flange according to claim 2, wherein the extending inner part has a gradually reduced thickness along the cable direction from the flange.

4. Cable flange according to claim 1, wherein the flange comprises a leakage test recess between the flange and the cable and a passage to at least one side of the flange comprising a block and bleed valve.

5. Cable flange according to claim 1, including a hose or pipe extending from said extended section along a predetermined length of the cable, the hose being sealed against said extended part in one end and the cable in the second end.

6. Cable flange according to claim 5, wherein a tape or similar is applied to said extended section and first end of said hose for sealing said first end.

7. System comprising a pipe or hose extending through a wall, each end of said pipe or hose being connected to a cable flange according to claim 1 , wherein said pipe is connected to each flange, the extending parts being oriented away from said hose.