FR2489034A1 - Wax impregnation of multistrand cables using pressurised emulsion - to increase fluidity of impregnating material - Google Patents

Abstract

Impregnation under pressure of a multistrand cable core, to exclude moisture, is achieved by passing the core through a pressure chamber contg. an emulsion of a hydrophobic fluid and an inert gas such as nitrogen or carbon dioxide. For impregnation with a paraffin, petroleum jelly ('vaseline' RTM) or a polyethylene wax, the emulsion is less viscous than the base fluid, and penetrates more thoroughly and/or more quickly. Better impregnation may allow the amount of material needed to exclude moisture to be reduced by up to 50%.

Description

Method for impregnating a cable with a sealing material
The present invention relates to a method of impregnating a cable with a sealing material.

 It is known that cables, in particular telecommunications cables, have a core formed of a sometimes very high number of copper or aluminum wires insulated by means of a plastic material, these wires being assembled and then covered in length or in a helix d '' an insulating tape made of paper or non-woven material of the polyester type or of an extruded insulator, constituting a good electrical insulator, then optionally a metallic tape forming an electrical screen also applied lengthwise or helically, and finally of a outer sheath made of a plastic material or elastomer extruded over an electric screen.

 It is also known to impregnate the cable with a viscous molten sealing material injected under pressure generally before the installation of the sheath.

 The purpose of this material is in particular to prevent the propagation of moisture in the cable when the outer sheath is damaged.

 Such a viscous material is in particular a paraffin, petroleum jelly, a polyethylene wax.

 However, we realize that it is sometimes very difficult to penetrate the core of the cable, therefore between the wires of such materials, which results in prohibitive consumption of the latter.

 The present invention overcomes such a drawback, and it relates to a method of filling a cable with a sealing material, making it possible to achieve significant savings in consumption of said material.

 The subject of the invention is therefore a method of impregnating a cable with a sealing material by passing the core of said cable through an impregnation enclosure, characterized in that said impregnation enclosure contains said material sealing in the form of an emulsion with a gas which does not react with this material under the conditions of temperature and pressure of impregnation.

 Other characteristics and advantages of the invention emerge from the description which follows, given by way of purely illustrative but in no way limiting, with reference to the appended drawings which illustrate very schematically in Figures 1 and 2 the implementation of the process of invention according to two variants, and in FIG. 3, a cable produced by the implementation of the method according to the invention.

 In FIG. 1, the reference 1 designates the core of a cable made up of several insulated wires assembled in the known manner, 2 being an impregnation enclosure of known type in which the core 1 passes, allowing hot impregnation and under pressure by a sealing material 3 such as for example petroleum jelly, paraffin, polyethylene wax.

 According to the invention, said sealing material 3 is in the form of an emulsion with a gas such as nitrogen or carbon dioxide which does not react with said material under the conditions of temperature and pressure of impregnation. the enclosure 2 is supplied with an emulsion under pressure by the tube 4 emerging from a pump 5 in which the emulsion is produced. To this end, the pump body is supplied, for example, with petroleum jelly through the pipe 6, while the gas arrives through the pipe 7.

 In the variant shown in FIG. 2, the emulsion is produced "in situ" in enclosure 2.

 For this purpose, a pump 9 is used which receives petroleum jelly through the pipe 10 and delivers it into the impregnation enclosure 2 through the pipe 8, while the pressurized gas is supplied via a pipe 11.

 The core of the cable impregnated in accordance with the above is then provided with its insulating tape for its metallic screen and with its external sheath in the known manner.

 Figure 3 shows such a cable.

 It therefore comprises the core 1 successively covered with a paper tape 12 with a layer of petroleum jelly 13, with a plasticized aluminum tape 14 forming an electrical screen and finally with the external sheath 15 made of polyethylene.

 your implementation of the method according to the invention ensures very good impregnation of the core while saving at least 50% of material compared to conventional methods.

 The invention is implemented in particular in submarine telecommunications cables.

 Of course, the invention is in no way limited to the embodiments described, but on the contrary covers all of its variants.

Claims (7)

1 / A method of impregnating a cable with a sealing material by passing the core of said cable through an impregnation enclosure, characterized in that said impregnation enclosure contains said sealing material in the form of an emulsion with a gas which does not react with this material under the conditions of temperature and impregnation pressure. 2 / A method according to claim 1, characterized in that said gas is nitrogen or carbon dioxide. 3 / Method according to one of claims 1 or 2, characterized in that said sealing material is a paraffin, a petroleum gel or a polyethylene wax. 4 / Method according to one of claims 1 to 3, characterized in that said emulsion is formed outside of said impregnation enclosure. 5 / A method according to claim 4, characterized in that said emulsion is formed in the feed pump of said impregnation enclosure. 6 / A method according to one of claims I to 3, characterized in that said emulsion is formed inside of said impregnation enclosure. 7 / Cable impregnated by implementing the method according to one of the preceding claims.