The present invention relates to a device for feeding a liner into conduits. Piping is used in many applications to transport various fluids from one location to another. Depending on the application, the length of the piping or conduits may be on the order of meters to many kilometres. Piping that is laid on the ground, in the ground, on the seabed or in a ditch in the seabed, may for various reasons experience rupture or breakage. This may de due to internal or external corrosion, internal or external loads/strain, and/or movement of the ground.

Repair of piping may be costly and demanding, especially when the piping is long and inaccessible. A repair procedure may involve locating one or more ruptures, digging up the area around the rupture, and joining in a new length of pipe. It is understood that the costs involved with repairs may be extremely high if the piping runs over several kilometres on or under the seabed, the cost increasing multiple times if the piping in question has several ruptures and is in a generally poor condition. There have been presented several solutions for restoring the integrity of piping by introducing and arranging a liner inside a pipe. Some of these solutions are in common use and work well for their application. However, the conventional solutions have a number of shortcomings when the length of the piping to be lined exceeds a couple of hundred meters. Most conventional systems rely on air pressure to force the lining into the pipe. When the length of the piping exceeds a couple of hundred meters, the air pressure necessary to force the lining further into the piping becomes so high that it introduces significant problems in other regards. Firstly, air/gas is compressible, and as the length of the lining increases, the pressures required increase disproportionately. Secondly, air under such high pressures introduces unacceptable safety risks. If a leak or rupture should occur, the result could be an explosion that could harm equipment and people. Thirdly, the high pressures demand use of support structures that are cumbersome and expensive to handle. Furthermore, the pipe lining material is conventionally coiled onto drums when being transported to the pipe repair site. Each drum can hold a limited length of lining, but seldom more than a couple of hundred meters. In conventional lining methods using air to run the liner into conduits, the entire lining on the drum and the drum is pressurised. EP 1810814 (Kaneta) relates to a method and device for restoring conduits where a tubular pipe lining material is guided through first and second pressure chambers and attached to an eversion nozzle. The pipe lining material is held by a holding jack in the first pressure chamber, and is drawn into the second pressure chamber by lowering the first pressure chamber. When a prescribed length of the pipe lining material has been fed into the pressure chamber, the second pressure chamber is air tightly sealed, and the pipe lining material is everted and drawn out though the eversion nozzle by the action of fluid (air) pressure in the second pressure chamber. Thereafter, the first pressure chamber is raised, and the same operation is repeated to successively evert and draw out the pipe lining material from the second pressure chamber. Kaneta only describes the use of air as an eversion fluid.

GB 1044645 (Nelva) describes a process for lining the interior of piping. A lining is fed though a seal, the seal consisting of a roller seal, into a pressure chamber that is secured onto the pipe that is to be lined, by means of a collar. The pressure chamber is continuously fed by pressurized air as the lining is fed through the roller seal and everted into the pipe interior. Nelva only describes the use of air as an eversion medium.

US 2006/0093436 Al (Gearhart) shows a pipe liner eversion apparatus with a roller seal. The roller seal comprises a movable roller assembly and a rubber slot gasket communicating with the chamber and both sides of the pipe liner as the liner advances though the apparatus. Pressure is applied into a so-called pocket which acts on the liner to evert the liner into the conduit. Gearhart is not specific in regard to what kind of eversion medium is used, but the term "air tight" is used several times.

US 5942183 (Alexander) relates to a method for everting a liner using a compact apparatus. The apparatus includes a so-called sphincter valve which acts as seal or seal around the liner to be fed into the conduit. The sphincter valve constitutes a bellows that excerpts a pressure onto the outside of the liner and thereby seals the interface between the liner and the sphincter valve. Alexander describes the use of air or water as an eversion medium. The apparatus according to Alexander does not comprise a pressure chamber per se.

US 6390795 (Waring) describes an apparatus for installing a liner into a conduit. A relatively complex, multi-component seal is used to lead a flattened liner into an enclosed zone where an increased pressure is used to evert and move the liner through the conduit. Although the above mentioned publications suggest various kinds of lining evertion methods and apparatus that each may have their merit in applicable fields of use, none of them are suitable for lining greater lengths of piping. Furthermore, none of these solutions appear to have found industrial applicability. It is an object of the present invention to provide an apparatus and method that is suitable for lining long conduits. It is a further object of the present invention to provide an apparatus and method that is suitable for lining long conduits in a cost efficient and safe manner, requiring a minimum of auxiliary, bulky equipment. Another object of the present invention is to provide an apparatus and method that is flexible in terms of use and placement.

These and other objects are reached by means of an apparatus and method according to the appended independent claims. Further advantageous features and embodiments are indicated in the appended dependent claims.

By way of example, an embodiment of the present invention is described in the following with reference to the accompanying drawings, wherein:

Fig. 1 shows a side view of an embodiment of the present invention,

Fig. 2 shows a side view of the embodiment of Figure 1 during use, before the liner penetrates the conduit,

Fig. 3 shows a side view of the embodiment of Figure 1 during use, after the liner has penetrated the conduit and the pressure tight box is installed,

Fig. 4 shows a side view of the embodiment of Figure 1 during use, after the liner has penetrated the conduit, the pressure tight box has been installed and the liner has slipped through the seal,

Fig. 5 shows a top view of the embodiment of Figure 1 ,

Fig. 6 illustrates an alternative embodiment of the present invention,

Fig. 7 is a side view of an embodiment of the present invention illustrating in particular a fixing means prior to fixing of a liner, and

Fig. 8 is a side view of a detail of the embodiment of Fig. 7 illustrating the fixing means following fixing of the liner. Figs. 1 to 4 are side views of a pressure chamber 1 comprising a lock or a seal 2. A liner 3 is fed through the seal 2 into the pressure chamber 1 . The liner is everted and fixed to the pressure chamber as shown in fig. 1 a by means of suitable fixing means 4, e.g. a hose clamp, pressure cone, locking ring etc. A pressure medium 10 consisting of a liquid is fed through a liquid inlet 5. The pressure of the liquid may be monitored by a manometer 6.

The seal 2 comprises no moving parts, and according to one embodiment of the present invention, the seal 2 comprises two mainly flat face plates clad with sealing means 7. The sealing means 7 may consist of a block of suitable sealing material, e.g. a resilient material such as rubber or rubber like materials. Other sealing materials may also be used. The sealing means 7 may consist of different layers or sones of similar or different sealing materials. The two mainly flat face plates clad with a sealing means 7 are pressed and held together by means of a suitable adjustable clamp or fixing means 8, e.g. clamps that may be tightened to a sufficient degree by means of tightening means. The clamp 8 may comprise tightening bolts and/or springs. According to another embodiment of the present invention shown in fig. 6, the seal 2 constitutes a mouth, the mouth being provided with a flange 12. An elongated slotted block 13 (of resilient material) is arranged outside the flange 12. An elongated slotted support plate 14 is aligned outside the elongated slotted block 13, such that the flange 12, block 13 and clamp 14 form a sandwich-like construction. A clamp 15 comprises bolts or the like, which press the sandwich construction together, squeezing the block 13 and causing it to seal even tighter around the liner.

The liquid 10 used to pressurise the pressure chamber 1 may comprise water. In order to reduce friction between the liner 3 and the inner surface of the conduit 9, a lubricant may be introduced into the pressurising liquid. Good results have been achieved with a mix of sea water, silicone oil and soft soap. It will be appreciated of course that pure water, sea water, or other suitable liquids or mixes of liquids may work equally well. The seal 2, comprising a sealing material 7, is arranged and pressed together with sufficient force to make up a mainly liquid tight seal. The seal 2 comprises no moving parts, which is considered to be of significant importance in providing an efficient, cost effective, and compact pressure chamber 1 for lining the interior of conduits by means of a pressure medium comprising a liquid. In order to assist the easy movement of the liner through the seal, a lubricant may be sprayed or otherwise coated onto the liner surface as it is fed into the seal. This lubricant may comprise, for example, water with added soft soap and/or silicone oil.

The use of liquid as a pressure medium, in combination with the pressure chamber 1 described, provides a means for lining conduits of extended lengths compared to the methods and tools that are available and in use today. With the approach described here, means are provided that enable the lining of conduits that are several kilometres long. Tests have been conducted with success on conduits on the order of two kilometres, and measurements during the tests indicates that it should work for much longer conduits. This is in contrast to conventional solutions using air as a pressure medium which have proven to be effective only until a couple of hundreds of metres.

Fig. 5 is a top view of the pressure chamber 1. A clamp 8 is shown as the clamping means for providing a liquid tight seal 2 without any moving parts. The liner 3 is fed through the seal 2 into the pressure chamber 1 . The pressure chamber 1 may be positioned where desired as compared to an inlet of a conduit 9 (not shown on fig. 5). The liner 3 is fixed only to the pressure chamber 1 by means of suitable fixing means, and as the liner 3 is everted and starts to "grow", it may be guided into the conduit 9 (see figs. 1 to 4). The shape of the pressure chamber 1 is of course of importance. The pressure chamber 1 proposed here has a part cylindrical and part wedge shape, where the wedge tapers from the cylindrical part down to the seal 2. This shape ensures at least two things: a compact size and an oblong seal 2 that is suitable for providing a liquid tight seal without any movable parts. By arranging a suitable clamp or tightening means 8 on the two faces of the wedge, it is relatively easy to obtain the right clamping force on the sealing material 7. It is understood that other shapes and designs may be used with equal success, but the abovementioned design is currently believed to be close to the optimal design. In use, when wanting to line a conduit 9 of predetermined length, a liner stub is threaded through the seal, pulled through the pressure chamber 1 , turned inside out, and fixed to the opposite, cylindrical end of the pressure chamber 1 by means of suitable fixing means 4 (see fig. la). The space 1 1 inside the pressure chamber 1 and outside the liner 3 is then filled with the pressurising liquid 10 while air is bled out of the system. The pressure is then built up to, preferably, 6-8 bars. Preferably, the pressure does not exceed 10-12 bars. The liner 3 is fed through the seal 2 and pressure chamber 1 and as the everted liner 3 starts to "grow", it is guided into the conduit 9 while the liquid pressure medium 10 is continuously supplied. The pressure of the liquid pressure medium 10 is maintained within desirable limits (see fig. 1 b). The liner 3 is continuously everted further into the conduit 9. If the conduit 9 to be lined is of a significant length, the liner 3 may be fed from a container instead of from conventional drums. This is possible because the solution does not rely on having to pressurize the entire liner 3 with air before it is everted into the conduit 9.

When the end of the liner is close to the seal, e.g. 5-40 cm, the feeding of the liner is stopped. A pressure tight box 15 is then mounted over the liner end, so that the pressure can be maintained in the system when the liner end is pulled through the seal. The pressure tight box 15 is shown in use in figs. 3 and 4. The liner 3 has been previously glued or otherwise tightly closed so that it forms a "toe-box". The liner end is then released through the seal 2 as pressurising liquid 10 is continuously fed into the pressure 10 chamber and pressure is maintained at the desired level, until the "toe-box" of the entire liner 3 is everted and has reached the other end of the conduit 9 to be lined. The "toebox" may then be cut of and the liner may be fixed (or not) according to preference on the far other end of the conduit 9, with may be many kilometres long. Fig. 7 and 8 show an advantageous embodiment of a fixing means 4, in the form of a pressure cone. According to this embodiment, the pressure chamber 1 comprises a cone shaped mouth 16 and a flange 17. A mating cone shaped locking ring 18 with a flange 19 may be clamped outside the cone shaped mouth 16, thereby sealingly and securely holding onto the liner 3, which is fitted outside the cone shaped mouth 16, whereupon the mating cone shaped locking ring 18 is threaded over the cone shaped mouth 16 and liner 3, whereafter the cone shaped locking ring 18 is tightly fixed to the cone shaped mouth 16 by means of bolts 20 and nuts 21 squeezing together the flanges 17 and 19. Other fixing means 4 may of course also be envisaged.

The embodiments described here provide a compact, reliable and user-friendly device, consisting of a pressure chamber 1 of the aforementioned kind and with a seal 2 without movable parts, that is suitable for lining extended lengths of conduit 9 by means of a liquid pressure medium 10. As opposed to solutions using air as a pressure medium, the embodiments provide a much safer solution, without the risk of spurious ruptures causing dangerous explosions. Air is a highly compressible medium, and in addition to the abovementioned drawbacks, it is much more difficult to control than a liquid. Whereas pressure control of a liquid pressure medium is predictable and straightforward, the compressible nature of air causes large fluctuations in pressure, surges, cork effects etc. The risk of these undesirable effect only increase as the length of the conduit to be lined increases.

Since a liquid pressure medium is an incompressible medium, the everting of the liner 3 into the conduit 9 becomes an hydraulic process. This simplifies the demands placed on the pumps, etc., needed to feed and maintain pressure in the liquid pressure medium 10. As opposed to this, the use of air as a pressure medium requires increasingly large compressors as the length of the conduit 9 increases.