This invention relates to the lining of pipelines and passageways, and concerns those lining methods, which are now well established, wherein a flexible lining tube comprising or including one or more layers of resin absorbent material carries a curable synthetic resin system which impregnates the said absorbent layer or layers, and wherein after the flexible lining tube is applied to the pipeline or passageway, the resin is cured or caused to cure whilst the lining tube is held to the passageway surface by fluid pressure so that the lining tube in effect forms a hard rigid pipelining on the passageway surface which remains in position after the said fluid pressure is removed.

Examples of these methods of applying lining tubes to passageways are disclosed in US Patent Nos 4009063 and 4064211. In each of these patent specifications the main method used for curing of the resin is to apply heat by circulating heated fluid through the flexible tube when held to the passageway surface. Said heated fluid also forms the means of applying the fluid pressure.

The use of heat for curing the resin means that the resin system will be of a heat cure type, and it typically will be a polyester or epoxy resin system. The disadvantage of using heated fluid, and in particular heated water, is that curing takes a long time, and furthermore it is expensive, because a large volume of water is required for the heating process.

It has been proposed in US Patent No 4581247, that if an appropriate resin system is used, being one which curing can be effected by the application of light energy, then curing may be effected by the imparting of light energy onto the

flexible tube whilst it is held to the passageway surface. Specifically, it is suggested that ultraviolet light be used and that the curing system be one which can be activated by ultraviolet light radiation.

One of the difficulties which arises in connection with the use of ultraviolet light is that when water is used for the inflation of the lining tube to hold it to the passageway surface, the lights must be immersed in the water. It is important therefore that relatively clean water should be used as otherwise the ultraviolet light penetration is impaired. Because of the need to use clean water according to the suggested method in the said US patent, when the lining tube is being applied to a sewer, it is necessary to divert the sewage away from the section of the sewer which is being lined at any particular time, and to charge it back into the sewer at a position downstream of such section. This diversion of the sewage is known as overpumping, and typically the sewage is pumped from the sewer upstream of the section of sewer which is being lined, to ground level, over the ground, and then back to the sewer. Not only does this increase the cost of the lining operation considerably, as overpumping is expensive, but also there is the constant risk that the overpumping pipework may suffer a failure causing the spillage of sewage at ground level, which clearly could lead to a health hazard and at best would attract public criticism.

There is therefore clearly room for improvement in a number of aspects of the lining operations of the type to which the present invention relates, but a principle object to the present invention in a preferred form is to provide a system whereby curing can be effected by curing light means whilst overpumping is avoided.

According to an ancillary object of the preferred form, a particularly convenient apparatus is provided which enables effective curing of the resin system of the lining tube whilst still permitting avoidance of the said overpumping.

In accordance with the present invention in one aspect there is provided a method of lining a pipeline or passageway using a flexible lining tube which is impregnated with a curable synthetic resin, wherein the lining tube is held to the pipeline or passageway surface by fluid pressure, curing of the resin is effected by moving curing means along the inside of the passageway and inside the lining tube, and wherein the said curing means is an annular structure having a central aperture through which the fluid pressure medium can pass, the method further comprising the step of pumping a second fluid into said annular structure to prevent the first fluid from entering the annular structure, said second fluid either being heated to heat the lining and cure same, and/or serving as a means to isolate curing means such as radiation source means in the annular space from the first mentioned fluid pressure means without impairing substantially the radiation curing capability of said radiation source means.

Where the second fluid performs or assists curing it preferably is hot water, steam or a heated gas. The use of steam is particularly desireable because of its high temperature and low volume when condensed.

When the radiation means when provided, is UV lights, the second fluid should be transparent or translucent to the light radiation and preferably is clean water.

Other forms of radiation source can be used such as microwave sources, ultrasonic sources, radio wave sources and so on.

In a preferred case, the resin used is a light curable resin and said annular structure houses light sources; the second fluid is applied to the annular structure at a pressure greater than that of the pressurising fluid which keeps the lining tube inflated.

The said annular structure preferably comprises a central sleeve and end flanges extending outwardly from the sleeve ends, said flanges being of a character to form a seal or partial seal with the inside of the lining tube thereby to retain as much as possible the said second fluid inside the annular cavity formed between the flanges on the one hand and between the tubular lining and the sleeve on the other hand.

The annular structure may be designed to allow some of the second fluid to escape past the edges of the flanges which seal against the flexible lining tube.

The flexible lining tube is preferably maintained in position on the passageway surface by means of the fluid e.g. sewage, which normally flows through the passageway, whereby overpumping may be avoided.

The flexible lining tube when in position on the pipeline or passageway preferably comprises an inner plastics material coating or membrane, whilst the said layer or layers of resin absorbent material containing the resin therein are arranged between the said coating or membrane and the surface of the passageway.

The lining may be fabricated according to any suitable construction either known or yet to be devised, and the layer or layers may be impregnated by conventional methods, for example as described in US Patent No 4366012.

The lining tube preferably is everted into the pipeline or passageway, for example as disclosed in said US Patent No 4064211, and when eversion has been completed, the trailing end preferably is opened albeit to a restricted extent, to allow the flowing fluid in the passageway to pass therethrough and to maintain the lining tube in inflated condition on the passageway surface as the light curing means is pulled therethrough by means of a rope or the like.

As to the light sources which are used, a plurality of such sources is employed, and these may be grouped in for example threes arranged in alignment in a direction parallel to the axis of the sleeve of the annular structure. The groups may be arranged peripherally around the sleeve, and they will be positioned on a pitch circle in order to ensure that the light falling on the lining tube to cure the resin does not suffer total internal reflection from the lining tube surface. This is a matter of the geometrical position of the light groups, but typically if the diameter of the lining tube when on the passageway surface is D, the annular structure flanges will have an outer diameter of D, and typically have an inner diameter of 0.6 D, whilst the groups of light sources will be arranged on a pitch circle diameter of the order of 0.7 D.

The said flanges may comprise elastomeric rubber like plate members, but in an alternative construction the edges of the flanges may be inflatable so as to define inflated rings which can rest against the in place lining tube to seal against the inner surface of same.

The invention also provides a light cure apparatus comprising an annular structure made up of an inner sleeve and end flanges extending outwardly from the ends of the sleeve, and including light source means mounted externally of the sleeve

and between the flanges.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:-

Fig. 1 is a schematic view showing a lined length of underground sewer wherein curing of the lining is in operation;

Fig. 2 is a perspective view showing the curing apparatus of Fig. 1;

Fig. 3 is a sectional view of the apparatus shown in Fig. 1;

Fig. 4 is a longitudinal section of the apparatus of Figs. 2 and 3, when in position and effecting curing of the lining; and

Figs. 5, 6, 7 and 8 show as a sequence of stages, a practical embodiment of carrying out the method of the invention.

Referring to the drawings, and firstly to Fig. 1, which is a schematic sectional elevation through an underground sewer pipe 10, the section of pipe 10 between manholes 12 and 14 leading from ground level 16 to the pipe 10, is shown as lined with the curable flexible tubular lining 18. The sewage which flows in the pipe 10 is illustrated by reference 20, and for the purposes of explanation only, the sewage is shown as filling the sewer pipe, and extending up the manholes to level 22, whereby the tubular lining 18 is maintained inflated by the actual flowing sewage. The lining 18 is shown as being open at its ends, so that the sewage can flow freely therethrough. A practical method of inserting the lining and causing the sewage to flow therethrough is

explained in relation to Figures 5 to 8.

Inside the liner tube 18 is shown a curing apparatus 24, the details of which will be given hereinafter, but the apparatus 24 progressively cures the curable synthetic resin which impregnates the lining tube 18 as explained herein, but it does so in a progressive manner insofar as the apparatus 24 is pulled through the lining tube 18 by means of a pull rope 26 and winch 28 to which the pull rope is connected. The curing apparatus 24 is moved therefore progressively along the inside of the lining tube as indicated by arrow 30, curing the resin which impregnates the tube as described hereinbefore, as it proceeds. The hatching lines used in Fig. 1 are to indicate that section of the lining tube which has already cured under the influence of the curing apparatus. The curing apparatus embodies curing lights, and the resin which is used for the lining tube is one which will cure under the influence of light radiation and in particular UV light radiation. The light sources as used in the apparatus 24 will therefore be UV sources.

It will be appreciated that the number of light sources used and the speed of movement of the apparatus 24 will be related to the rate of which the resin cures, and the thickness of the lining tube 18. These parameters will have been established by laboratory testing so that the installer of the lining tube 18 will know exactly how many lights to use and the speed at which the apparatus should be moved along the lining tube.

The apparatus 24 is annular to allow the sewage 20 to flow therethrough, and it has two further cable or rope or pipe connections thereto namely an electrical supply cable 32 and a water hose 34, coupled respectively to an electrical supply 36 and a supply of clean water 38 contained in a service

vehicle 40 located at ground level. The electrical supply 32 is for the purpose of powering the light sources, whilst the clean water supply is for flushing clean water over the light sources to keep them isolated from the sewage for the purpose as described hereinafter.

If reference is now made to Figs. 2, 3 and 4, the detail of the curing apparatus will be understood. As shown in Fig. 2, the apparatus 24 is an annular structure and is provided with a central aperture 42 through which the sewage 20 can pass in use. The annular structure is defined by an inner sleeve 44 to the ends of which are attached flanges 46 and 48. These flanges extend outwardly so as to create an annular cavity 50 in which the light source assemblies 52 are located. Each assembly 52 can be considered as a tube or rod arrangement extending between the flanges 46 and 48. These rods are arranged on a pitch circle which is approximately 0.7 times the diameter of the flanges, and the flanges will be configured so as to be a neat fit in the lining tube 18 as shown in Figs. 1 and 4.

The light tubes 52 are arranged on this diameter in order to give best light penetration into the lining tube 18, and specifically to avoid total internal reflection in relation to a light tube 18, which would mean that in use no light would penetrate the tube 18.

In this embodiment there are nine light tubes 52 equiangularly spaced on the aforesaid pitch circle, and as shown in Fig. 4, each tube 52 is made up of three light sources 54, 56 and 58 which are spaced and are in alignment along the length of the tube. Each of the light sources may comprise typically a one kilowatt light, and the rods 52 may be backed by parabolic or other reflectors in order to concentrate the light issuing therefrom outwardly and onto

the lining tube 18.

In Figs. 3 and 4, the assembly 24 is shown in engagement with the inner surface of the lining tube 18. This tube 18 preferably will be constructed as set forth in said US Patent 4366012 in that it comprises an inner coating or membrane 60 of polyurethane or the like, and an outer layer or layers 62 of fibrous felt which is or are impregnated with the curable synthetic resin.

Fig. 4 shows the electrical supply cable 32 by which power is supplied to the lights, and also shown is the clean water pipe 34 which couples to the annular space 50 and in use, for example in the circumstances shown in Figs. 1 and 4, clean water is pumped through pipe 34 and into the annular space 50 in order to flush this space to prevent the sewage, which may be turbid and opaque, from covering the rods 52. The clean water 34 is at a higher pressure than that of the sewage and so it will bleed past the outer edges of the flanges 46 and 48 and into the surrounding sewage. This flow of clean water is maintained as the assembly 24 passes along the inside of the tube in order to cure the resin therein.

As shown in Fig. 4, the interior diameter of the sleeve 44 of the assembly 24 is in the order of 0.6 times the diameter of the inside of the tube 18. A central opening of this size has been found to be suitable to permit the sewage to flow at a satisfactory rate, even although there will be a pressure differential in the sewage between the upstream and downstream sides of the assembly 24.

In order to enhance the sealing of the flanges 46 and 48 to the inner surface of the lining tube 18, these flanges may be constructed of an elastomeric or rubber like material having natural sealing qualities, or alternatively the flanges may

be inflatable or have an inflatable bead at the sealing edge. It is preferred in any event that the clean water supplied through tube 34 will flush past the sealing edges 46 and 48 of the assembly 24 in order to enhance the movement of the assembly along the inside of the lining tube.

Any suitable method of inserting the lining tube and the assembly 24 may be adopted in order to achieve the arrangement shown in Fig. 1, and one practical method is illustrated by the schematic representations Fig. 5, 6, 7 and 8, and referring to these drawings, and firstly to Fig. 5, this is a view similar to Fig. 1 but showing how the lining tube and curing apparatus 24 are initially arranged in the manhole 12 prior to lining and curing.

In the arrangement shown, a T-shaped housing 64 is located at the base of manhole 12. In one arm of the housing 64 the apparatus 24 is loaded and it has connected thereto a pull rope 66 which eventually will serve for pulling the apparatus 24 along the lining tube as shown in Fig. 1. Rope 66 is brought to ground level through the leg 68 of the T-housing and also brought through the leg to ground level are the electric supply cable 32 and the water supply pipe 34.

The lining tube 18 extends through the leg of the T of the housing, and then it is turned back upon itself and banded to the open end of the other arm along with the leading end of a flexible prelining tube 72 as indicated at location 70. The prelining tube 72 is provided with a rolling ring 74 for the purpose and operation as set forth in International Patent Application No PCT/GB92/01508. The majority of the lining tube 18 is stored at ground level as indicated by reference 76 and it is housed in an enclosure 77 which may be a tent keeping it isolated from natural light which could cause problems with pre-curing of the resin.

In this condition, the sewage can flow over the housing 64 as indicated by the arrows 78, and can continue to flow along the section of the sewer 10 which is to be lined.

Finally, a submersible pump 80 is located in the sewer 10 upstream of the housing 64, and the submersible pump 80 has an outlet hose 82 by which sewage can be pumped from the sewer up and into the top of the leg 68 so as to flow into the housing 64 and cause the tube 18 to be everted into and along the passageway as will be described.

In the arrangement of Fig. 5, the lining and apparatus are set ready to commence the lining operation. To commence this operation, the submersible pump 80 pumps sewage from the sewer 10 up and into the top of the housing 64. The housing fills with sewage and the pressure thereof causes the lining tube 18 to commence eversion into and along the sewer 10 as shown in Fig. 6. The lining tube 18 inflates up and onto the sewer surface so that the sewage no longer flows over the housing 64 as indicated in Fig. 5. The preliner 72 is simultaneously applied to the pipeline surface to the outside of the lining tube.

This operation progresses until the trailing end 84 of the lining tube reaches manhole 14 as shown in Fig. 7. The length of the lining tube will have been calculated in accordance with the length of the sewer to be lined. To this trailing end 84 is connected a hold back rope 86, the purpose of which is to control the in-feed of the lining tube so that it does not "run away" due to the pressure of the sewage causing the eversion. Trailing end 84 is sealed, but it will subsequently be cut open to allow the sewage to flow therethrough. Before this takes place, the end 84 is clamped by a pair of clamping rollers 88 which can be moved together

and apart, and at the same time the hold back rope 86 is connected to the pull rope 66 connected to the apparatus 24.

When the trailing end 84 has been clamped, it is cut open and the leading end of the hold back rope 86 is pulled through the cut end 84. At the same time the rollers 88 are opened slightly to allow the sewage to flow therethrough as indicated in Fig. 8 by arrows 90. The rope 86 is pulled from ground level at manhole 14 by any suitable means (not shown) which in turn pulls the rope 66, which in turn moves the apparatus 24 along the inside of the lining tube 18 in the same manner as illustrated in Fig. 1.

From a consideration of the above specific embodiment, it will be appreciated that the invention has wider application insofar as as an alternative to using light radiation sources other forms of radiation sources can be adopted such as ultra sonic sources, microwave sources, electro magnetic sources, radio wave sources, as long as the curing resin is selected to match the type of radiation involved. In each case, a fluid will be pumped into the annular cavity in order isolate the radiation sources from the surrounding fluid which inflates the lining tube, and which is likely to be contaminated sewage.

Combinations of these radiation sources can be used if required, and furthermore, and equally interestingly, instead of using radiation sources, the fluid which is pumped into the annular cavity can itself form the curing medium. For example if the cavity is filled with hot water or heated gas, or preferably steam, at a pressure sufficient to keep the pressurized fluid out of the cavity, then the heat in the second fluid can be used to effect cure of the resin at that section embraced by the annular space. The use of steam is particularly preferred, because a large volume of steam can

be generated from a relatively small amount of water which means that the supply vehicle can be kept smaller, and steam escaping from the annular chamber will quickly condense into the pressurizing fluid when it is sewage, providing a particularly advantageous arrangement.

It will furthermore be appreciated that radiation sources can be used in combination with the second fluid for effecting the curing.

An extremely effective and efficient method and apparatus for the curing of impregnated lining tubes is provided. Considerable advantage is achieved when lights are used in that the lights are flushed with clean water ensuring that effective light transmission is achieved, and the apparatus in all embodiments of the invention enables curing to be effected without any necessity for overpumping of the sewage in that it is annular in construction, and the sewage can flow through the centre thereof.