Technical Fi eld

The present invention relates to the lining of passages, particularly underground passages such as sewers. It is known to apply a lining of material to a wall of a passage by everting a prepared composite tube of plastics material so that the tube is held against the wall whi lst the pretreated material of the tube cures to a hardened state. This is described in published United Kingdom patent number 1449455. A shortcoming of this method is that the tube has to have two layers, one to keep the pressure medium, which is used for eversion, away from the pretreated material. The process of eversion itself necessari ly means that the thickness of the tube has to be limited. Further the pressure medium, if it is not a cheap material, like water, has to be recovered and this requires recovery apparatus.

In order to draw an uncured tube of plastic material into a passage of up to 200 metres in length it is necessary for the tensi le strength of the uncured material to be considerable. In general such materials do not have such st rength .

Disclosure of the Invention

It is an object of the invention to introduce a soft tube into a long passage and to use the tube so introduced for lining the passage. It is a further object of the invention to provide apparatus for effecting such introduction and lining.

According to the invention a method of introducing a soft tube into a long passage consists of laying the tube on a carrier and drawing the carrier into the passage.

The carrier may consist of a plurality of flat beds joined together to form a train, or a single long bed or mat.

According also to the invention a method of lining a passage consists of forming a tube of soft plastics material which is capable of being hardened over a period of time, laying the tube on to a carrier, drawing the carrier into the passage, inflating the tube into contiguous relationship with the walls of said passage and the surface of the carrier for a sufficient period of time to allow hardening of at least the material near the outer surface of the tube.

Preferably the material on the outer surface of the tube is treated with a hardener suitable for such soft plastics material before being laid on said carrier. Alternati ely the surface may be treated with hardener subsequent to introduction into the passage. As a further alternative the hardener may be incorporated in the bulk of the material of the tube prior to or during forming of the latter.

In the case where the outermost material has hardened the curing may be completed by the application of hardener to the inner surface of the tube after removal of the inflation pressure.

In the case where the hardener is incorporated in the bulk of the tube material to render it thermoset i ng the hardening process may be initiated and completed by elevating the temperature of the tube material whilst it is still inflated. This can be done by using or substituting steam as the inflating medium.

According also to the present invention apparatus for introducing a soft tube into a long passage comprises a carrier having a high longitudinal strength and so shaped as

to be able to constitute an alternative floor to the floor of the passage.

Preferably the carrier comprises a succession p i flat beds joined to each other by a coupling capable of sustaining high tension loads. In an alternative preference the carrier comprises a single elongated bed or mat incorporating a draught sustaining longitudinal reinforcement.

Description of the drawings

The invention wi ll now be described by reference to the accompanying drawings of which:

Figure 1 shows an underground sewer into which a carrier consisting of a train of flat beds and a tube are being introduced,

Figure 2a shows a side elevation of a flat bed,

Figure 2b shows an end elevation of the flat bed of figure 2a viewed in the direction of arrow A,

Figure 3 shows an elevation simi lar to Fig 2b of an alternative flat bed,

Figure 4 shows a cross section through a carrier formed by a mat ,

Figures 5a and 5b show views of a quick coupling for attaching two flat beds together,

Figures 6a,b,and c show steps i llustrating the inventive method.

Figures 7a,b and c show three steps i llustrating a second

variant of the method,

Figures 8a b andc show three steps illustrating a third variant of the invention and _*

Figure 9 illustrates the use of end fittings.

Best mode of carrying out the invention

In Fig.1 a sewer is represented by a passage 1 extending from an entry pit 2 to a terminal pit 3 both of which are excavated so as to expose the ends of the sewer, which is to be relined. A wire hawser 4 is fed into the passage 1 from pit 3 to emerge at entry pit 2. It is attached to the front of the first flat bed 5a. This has at its front end a clamp for holding gently the free end of a soft tube 6 of plastics material folded lengthwise to lay conveniently within the width of the flat beds 5a,b,c et seq. which constitute the carrier The hawser is pulled so as to draw the bed 5a into the passage 1 and as it enters a second bed 5b is coupled manually to it, which in turn is drawn in. As the succession of beds is assembled the tube 6 is laid upon them manually. A pulley 7, mounted on a suitable stand is placed in the terminal pit 3 to align the hawser with the passage 1.

Referring to f gs.2, each flat bed consists of a deck 8 which may be supported in the passage 1 by a contoured roller 10 at each end trunnioned on a pair of downwardly extending ribs 9 as shown in fig.2b. The rollers 10 are designed to deflect when pressure is applied to the deck 8 and allow the ribs 9 to seat along the whole of their Length on the passage and serve as a substitute floor.

Fig.3 conveniently shows how the support may simply consist of a pair of angled skids 11. It also illustrates how the

tube 6 may be folded and laid on the carrier.

Fig 4 shows a cross section through a carrier which is a relatively flexible mat 31 capable of bowing to the contour of the passage 1. Strips 32 are adhesively embedded in the mat 31 and extend throughout its length. These may be of any marerial capable of taking tensi le Load and could be metal or fabric. The number of strips 32 and their size are chosen depending on the size of the soft tube 6 to be carried and the maximum length of passage to be lined on a given occasion. In this embodiment the mat 31 may carry a soft tube 6 of thermosett i πg material.

Fig 5a is a plan view on the decks 8 of the beds 5a and 5b. The tai l end of bed 5a has has an elongated socket 13 which is capable of recieving in an interlocking manner a double curved tang 14 projecting from the front of bed 5b. As wi ll be seen from fig.5b, which is a cross section on Line BB in fig 5a, the bed 5b has to be elevated at an angle to engage the tang 14 with the socket 13 but whi lst the two beds remain longi udinally aligned they wi ll not separate. The beds 5 are made of the cheapest possible material consistent with strength and resistance to chemical attack.

In order to be able to unite the uπinflated tube with end fittings for the purpose of inflation and of preserving the continuity of the sewer through the pits 2/3 it is proposed that the first and last . bed of the train of beds be shorter than the others and shall be easi ly detachable to allow the placement of end fittings capable of allowing inflation connectors and attachment to other end fittings.

In fig 6a the tube 6 is shown in a deflated and folded condition on its carrier 5 within the passage 1. End fittings,not shown, are fitted to the ends to close these off and enable it to be inflated. The inflation is commenced

and, when it reaches a stage such as is shown in fig 6b in which there is still a free space 15, a draw wire is used to pull a spray head 16 secured to a feed pipe 17 along the Length of the passage 1.

During this time hardening promoting liquid chemical is pumped through the pipe 17 and out of the spray head 16 to soak the outer surface of tube 6. Thereafter the tube 6 is fully inflated to the state seen in fig 6c and the pressure is kept high Long enough for the tube 6 to cure in this position ie. firmly pressed against the walls of passage 1.

As an alternative to drawing the spray head 16 along the passage 1 a perforated pipe 18 may be attached lengthwise to the top of the tube 6 during or soon after it is formed. This embodiment is shown in fig.7a,b and c. The pipe 18 perforated along its whole length is adhered to what will become the top of tube 6 whilst the latter is still soft. The tube 6 is inflated as before so that it takes on a more rounded form and hardener, pumped through the pipe 18 and out of the perforations flows smoothly over the tube 6. The tube 6 is fully inflated as before and no attempt is made to withdraw pipe 18. The pipe 18 might be constituted by a woven pipe of relatively loose weave so that the hardening promoting chemical effuses from it on pressurising

The interior of the tube 6 is treated with hardener by drawing a soft wheeled carriage, on which is mounted a 360 degree spray head for the chemical, through the tube whi 1st spraying.

In fig. 8a a jaw 33 defines a slot 34 into which the free squared end of the mat 31 described with reference to fig. , fits. The jaw 33 has a ring 36 fixed to it at one end to receive the shackle 35 of the hawser 4. The end of soft tube 6,in this case being of a thermosettiπg material is

folded lengthwise and laid on the aw 33 or a shield 38 attached to it and the remainder of the length of tube 6 is laid on to the mat 31 as it is drawn into the passage by the j aw 33. ,

Fig.8b shows an enlarged view of a longitudinal cross section on line CC of the jaw 33 as seen in fig.8c and the latter is a cross section on line DD in fig.8b. From these figures it can be seen that jaw 33 has three through holes 37 which line up with strips 32 so that a dri ll inserted, in turn, into each of holes wi ll bore a hole 38 through the mat 31 and the strips 32. Pins 39 pushed through the holes 37 and 38 wi ll transmit draught load from the jaw 33 to the mat .

It is expected that where the mat 31 is used to carry soft tube 6 into existing sewers there wi ll be sufficient bacterial growth on the walls to faci litate the passage of the mat 31. Where the mat 31 is drawn into dry passages a dispenser of cheap Lubricating materiaL such as soap solution or grease may be attached to the jaw 33 for distributing a coating ahead of the movement of the mat 31.

In every embodiment described, but particularly i llustrated in fig 9 the carrier (5,31) is arranged to be somewhat shorter than the Length of the passage 1 by an amount to allow for the insertion into the passage of a sleeve 40 having a flange 46. This may serve the purpose of mounting an adaptor plate 41 which is arranged to carry suitable air connectors 42,steam connectors 43, pressure gauges 44 and temperature gauges 45 for use during the inflating and hardening stages it being understood that whi lst air would be used to inflate the tube into firm contact with the walls of the passage, steam would be substituted during the hardening period in the case of use of t he rmosett i ng tube ateri a I .

Following hardening the adaptor plate 41 would be removed and the flange 46 of sleeve 40 would be avai lable for fastening a connecting piece 47 to join up with a corresponding flange 46 protruding from the next section of passage .

It is anticipated that the thickness of the tube 6 wi ll be between 2 and 8 millimetres but the scope of the invention is not limmited by these dimensions.

Obvious safety precautions such as restraining movement of the flanged sleeve whi lst the interior of the tube is under pressure should be employed.

The benefits conferred by the invention are considerable and allow renovation of existing sewers without the expense and public disturbance involved in excavating as in the present practice. A further benefit is the abi lity to line a new sewer or other under or over ground passage with a thin, inert liner making the whole of the passage resistant to corrosion or other attack and allowing the possibi lity of using cheaper passage construction material.