Background Art It will be appreciated that renovation is generally cheaper than replacement for most pipelines particularly when such pipelines are located in relatively inaccessible locations. An example of such a pipeline is a sewerage pipe which may pass about, under and through areas that would be difficult, if not impossible to dig up in order to provide a new pipe.

There are many ways of renovating a pipeline but the technique of interest with regards to the current invention is that involving a fabric tube appropriately impregnated with a curable resin to enable a rigid liner for the pipe to be achieved. This liner provides a renovating reinforcement for the pipeline.

Tubular pipeliner formed from fabrics and for use in renovation of pipes can be achieved by a wide range of methods including hosiery techniques but generally these fabric tubular linings are created from a sheet of fabric which is secured along a longitudinal edge to form a tube.

The fabric may be knitted, woven or a non-woven fabric. However, due to cost generally the fabric will be of the non-woven type in order to

provide the necessary matrix in which the curable resin can be impregnated.

The longitudinal edges of the fabric sheet used to form the tube can be secured together by stitching, butt welding or adhesive. However, whichever technique is used it is generally essential to provide an additional sealing tape beyond the edge bond in order to provide a substantial environmental seal. It is also normal for the fabric to be laminated with a barrier layer in order to further provide environmental containment for the pipeliner in use.

It will be appreciated the principal concerns with regard to the fabric tubular lining used to renovate pipelinings are its burst strength in use and its resilience to installation trauma. Burst strength is of particular importance when the pipeliner may be subject to pressurisation, whether intentional or transient, during its installation or use. For example, in one installation technique the curable resin is activated by inflating the pipeliner with hot water and such inflation may result in"ballooning" when the pipe to be reinforced has lost a substantial degree of its structural strength and so may allow the pipeliner to expand substantially beyond its intended dimensions. Alternatively, the pipelining may be used in pressurised water distribution systems or may be subject to gas pressurisation as a result of effluent decomposition between blockages in the pipeline. It is particularly important that the pipeliner and so the pipeline does not burst for a sewerage pipe in regions where ground water is collected for drinking etc. The other significant factor with regard to pipeliner performance is installation resilience. Upon installation the pipeliner will either be pulled or pushed through the pipe to be renovated.

Thus, there will be potential abrasion between the pipe to be renovated

and the pipeliner, extension of the pipeliner as it is pulled or pushed through the pipe and also simply due to the inherent trauma in construction activities.

With regard to burst strength it will be understood that the joint between the longitudinal edges of the fabric is generally considered the weak point of the tubular lining. This is partly the reason for the application of an environmentally sealing tape along this joint. One approach to improving this longitudinal joint within the tubular lining is to apply a further fillet, such as a strip of fabric, in order to reinforce the tubular lining at its longitudinal joint. This fillet can be applied either on the interior or the exterior of the longitudinal joint when the tubular lining is in use. However, it is far more advantageous and therefore common for the fillet to be applied on the interior of the pipeliner. By application on the interior of the pipeliner it will be appreciated that any pressure, in use, within the pipeliner will force the fillet into the longitudinal joint rather than away from such a joint. Typically, the fillet will be a similar fabric to that from which the tubular lining is created. Thus, the fillet will normally be a non-woven felt and will also become impregnated with the curable resin and so rigid upon activation.

As indicated above, as with other commercial activities cost is a significant factor with regard to choice of pipe renovation technique.

Unfortunately, the inclusion of a fillet within a pipeliner can greatly increase cost due to the multiplication of potential processing steps necessary to achieve an acceptable tubular lining for the pipeliner. Such increases in cost are due to the difficulty of attaching a fillet to the inside of the tubular lining. Thus, if at all possible the inclusion of a fillet is avoided possibly by increasing the gauge of fabric used and thus

increasing bond strength along the longitudinal edge joint and furthermore providing a more rigid pipeliner after the impregnant resin is activated.

Unfortunately these compromise palliatives on occasion can create their own problems. For example, for narrow pipe there is a limit to the gauge of fabric that can be used without significantly diminishing the cross-sectional area of the pipe to be renovated. Thus, attempts have been made to improve the process techniques to achieve a fillet location within the pipeliner. Again for illustration it has been suggested that the fillet could be attached to one side of the fabric longitudinal edge, the longitudinal edges joined and then the fillet attached to the other longitudinal edge of the fabric. An alternative, prior, approach is to turn short lengths of pipeliner inside out and then apply a fillet to the longitudinal joint. However, as indicated above both these approaches are expensive and not always satisfactory.

SUMMARY OF THE INVENTION It is an objective of the present invention to provide a tubular pipeliner construction including a fillet and which can be more readily achieved using known processing techniques and relatively cheaply.

In accordance with the present invention there is provided a tubular pipeliner suitable for use in renovating pipelines characterised in that the pipeliner comprises a fabric layer with longitudinally extending edges, a fillet and a sealing tape, the fabric layer having been formed to a tubular structure so that the longitudinal edges are presented adjacent one another with a fillet portion of the fillet therebetween and secured in said presentation by securing the fillet with said fabric layer with the sealing

tape sealed to marginal portions of the fabric layer adjacent the edges on the outer surface of the tubular pipeliner, whereby to provide the tubular pipeliner.

Preferably, the fabric is laminated with a barrier layer and said sealing tape is secured to the barrier layer.

The fillet may have a ribbed or bowed or stepped configuration.

The fillet may be simply secured to the fabric through its flats or along the surface of the longitudinal edge as well.

The mesa of the fillet may be adhered to the sealing tape or arranged to be substantially free for relative movement therebetween.

The fillet can be constructed and formed from a fabric similar to or the same as the fabric layer of the tubular pipeliner.

Brief Description of the Drawings Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 illustrates the first embodiment of the present invention where a fillet is created using a former; Figure 2 is a schematic illustration of a fillet construction; and,

Figure 3 is a schematic illustration of the fillet construction illustrated in Figure 2 presented in accordance with an alternative embodiment of the present invention.

Modes of Employing the Invention By having a gap between the two longitudinal wall edges of the pipeliner fabric to make a seam in the pipeliner and by introducing a fillet from the underside, it is possible to present and secure the longitudinal edges, the fillet and a sealing tape in one operation.

Figure 1 is a schematic illustration of one embodiment of the present invention. Only the joint is illustrated in an end elevation and it will be appreciated that the fabric layer 1 extends round to form a tubular lining. Respective longitudinal edges 2,3 of the fabric 1 are presented with a gap there between. In accordance with the present invention a fillet 4 is arranged to penetrate the gap between the edges 2,3.

In the embodiment illustrated in Figure 1 the fillet 4 comprises a flat segment of material and is deformed into the gap between the edges 2, 3 using a former 5. As indicated previously, the fabric 1 when used for sewer pipe renovation will typically have a plastics material barrier layer 6 applied to provide an environmental sealing barrier for the pipeliner.

Thus, above the edges 2,3 and the fillet portion provided by a mesa section 7 of the fillet 4 a sealing tape 8 is secured. This sealing tape 8 will at least be secured to the marginal portions ie shoulder areas adjacent the edges 2,3 and so it may be possible for there to be a degree of relative movement between the mesa section 7 and the tape 8. Such relative movement may help avoid any stress induced problems as a result of

installation extension of the pipeliner etc. However, it may equally be that the section 7 is secured to the tape 8.

The whole joint section comprising the fabric edges 2,3 along with the fillet 4 and the tape 8 will be secured together in order that the presented positioned relationships between these elements is stabilised within the pipeliner. Such stabilisation may be achieved using a variety of bond methods including hot fusion bonding, adhesive or stitch technology.

Furthermore, several of these bonding techniques may be combined in order to achieve the most effective performance for the pipeliner but whichever approach is taken all operations will be performed using one tool header machine.

In accordance with the present invention a construction of pipeliner is achieved whereby the tubular lining can be created in one process operation. Thus, in addition to reducing manufacturing cost there may be additional advantages with regard to improved production rate and quality.

Generally the fillet 4 is secured to the fabric 1 about shoulder areas to the edges 2,3. As indicated above such bonding can be achieved using adhesive or a fusion bond. However, as an alternative the fillet 4 may simply be secured to the tape 8 and the shoulder areas being free.

When an adhesive or a fusion bond is used, it will be understood that the bond contact surface is greatly increased in comparison with a simple butt bond between the edges 2,3. Thus, the bond strength may be significantly increased in comparison with previous joint configurations.

The top surface of the fillet 4 may be coated or impregnated with an activatable adhesive. Similarly, the contact surface of the tape 8 may have

an activatable adhesive. Activation may be using heat or solvent.

However, for convenience heat will be the preferred approach as this will allow more spatial and distributive control.

The former 5 may be arranged such that the fillet 4 may be moulded about the former 5 to a fillet configuration as illustrated i. e. ribbed or bowed or stepped.

In Figure 2 an alternative fillet construction is illustrated. This alternative fillet 21 comprises a base strip 22 of fabric combined with a fillet portion consisting of a ribbon of fabric 23. The strip 22 and ribbon 23 may be combined using a fusion bond, adhesive or using a stitching technique. This alternative fillet 21 is illustrated in Figure 3 as part of an alternative pipeliner configuration.

In Figure 3, the fillet 21 again is located with its ribbon 23 in the gap between the longitudinal edges 24,25 of a fabric 26. This fabric 26 again is formed into a tubular structure with the longitudinal edges 24,25 secured together as outlined below to create the tubular lining of the pipeliner. The base strip 22 of a fillet 21 is secured to the fabric 26 about the shoulder areas of the edges 24,25 using an adhesive, a fusion bond or stitching technique. However, an adhesive or a fusion bond is preferred in order that the contact bond area between the fillet 21 and the fabric 26 is sufficiently great to ensure a robust and strong bond for the pipeliner is achieved. A sealing tape 27 is applied to the combination of edges 24,25 and fillet 21 in order to provide an environmental barrier. The sealing tape 27 is secured to the normal laminated barrier layer 28 of the fabric 26. The bonding technique used is normally an adhesive or a fusion bond.

The sealing tape 27 may not be specifically secured to the fillet 21 in order

to allow a degree of relative movement and so diminish the prospects of bond failure during a trauma of pipeliner installation within a pipe for renovation.

The sealing tape 8,27 used in accordance with the present invention is preferably of the same material type as the barrier layer 6,28 used to provide an environmental barrier for the fabric 26. Thus, the extensivity of the barrier layer 6,28 material around the pipeliner is substantially equalised and again potential differentials which could precipitate bond rupture during the trauma of pipeliner installation are relieved.

Suitable plastics material types for the barrier layers 6,28 include polypropylene, polyurethane and ionomeric resins for example as supplied under the trade name Surlyn.

Once manufactured the tubular pipeliner in accordance with the present invention will be impregnated with a curable resin. This impregnation process, as with the installation process which follows, is generally traumatic to the pipeliner and again unless care is taken with regard to the strength of the pipeliner construction and the sealing tape relative to the barrier layer 6,28 damage can occur. The curable resin will also impregnate the fillet 4,21 and so, upon activation of the resin, the fillet 4,21 will become similarly rigidised as the fabric 1,26. As indicated previously the fabric 1,26 will generally be a non-woven felt.

Such non-woven felts are relatively cheap and provide an adequate matrix in which the curable resin can be impregnated for subsequent activation.

For example, a suitable fabric 1,26 would be a polyester non-woven felt

with a weight in excess of 800 g per square metre and a gauge in excess of 4 mm One manner of securing the fillet 4,21 to the fabric 1,26 is to present the fillet in the gap between edges 2,3; 24,25 and then provide stitches which extend through marginal portions either side of the edges 2, 3; 24,25 and into the flat portion of the fillet 4,21. The holes created by the stitches or staples used to secure the fillet 4,21 to the fabric 1,26 will then be covered by the sealing tape 27 applied using a fusion bond or adhesive. It will be appreciated that the post application stabilisation of a stitch bond is generally not a consideration. However, the use of an adhesive or fusion bond necessitates a consideration of the necessary time for bond stabilisation i. e. adhesive curing or fusion bond cooling, during which bond strength may not be sufficient before application of the sealing tape 8,27.

As indicated previously it may be advantageous for the top surface of the fillet 4,26 i. e. mesa section 7 or ribbon 23 to be substantially independent of the sealing tape 8,27 respectively. Thus, these portions may be coated to be non-adhesive and/or non-stick. Furthermore, a lubricant may be applied to these surfaces in order to facilitate relative movement between such surfaces and the surface of the tape 8,27.

In this structure or that where the fillet 4,26 is stitched in place as described above, the flat portions of the fillet 4,26 adjacent the marginal portions either side of the longitudinal edges 2,3; 24,25 of the fabric may then be free of any adhesive. When the fabric is impregnated with curable resin, the resin can penetrate through the flat portions of the fillet and into the marginal portions of the fabric. In either case the pipeliner will have

continuity of the curable reinforcing resin around the whole circumference of the pipeliner and the reinforcing resin will assist in retaining the fillet in place in the installed pipeliner. Where the flat portions of the fillet 4,21 are adhered to the marginal portions by a continuous adhesive layer as shown in Figures 1 and 3, there will still be continuity of resin around the whole circumference of the pipeliner but penetration of the curable resin into the marginal portions may be less. If the flat portions of the fillet are adhered by discontinuous adhesive deposits then penetration of the curable resin into the marginal portions of fabric is facilitated. The discontinuous deposits may be dots, longitudinal or transverse stripes, chevrons or of any other discontinuous deposit.

In the embodiment illustrated in Figure 1, it may be applicable after removal of the former 5 to apply an appropriately sectioned bead beneath the mesa section 7 in order to reinforce the fillet 4 configuration.

Furthermore, such reinforcing beads can be arranged to extend between manufactured lengths of pipeliner to provide pipeliner length keying and integration. The recess behind the mesa section 7 could also be arranged to facilitate a small degree of back tension useful during pipeliner installation against an inflating liquid. Finally, the recess behind the mesa section 7 could be arranged to accommodate a quick acting sealing compound released when a pipeliner is subject to significant over pressure such that this quick acting sealing compound is forced into any ruptures in the bond between the fillet 4 and the fabric 1. This quick acting sealing compound could be held in a distinct tube located within the recess or by applying an additional film layer below the fillet 4 with the result that a void is created where the former 5 is depicted in Figure 1. This further film would be rupturable during over pressure to release the curable compound into any fissures created in the fillet 4 due to the over pressure

cracking the curable resin. The void behind the mesa section 7 could also accommodate a traceable dye for use where there may be significant advantages in confirming whether or whether not a particular pipe has burst i. e. liberating pollutants into ground water and also possible to determine both the location and extent of rupture by consideration of the volume of dye and its spread. It will be understood that with current legislation in a large number of industrialised countries where in effect the polluter must pay for his pollution there will be significant advantages in confirming whether any pollution is a result of your particular pipeline and furthermore substantially by way of the liberated identifiable reagent the extent of the pollution release.

It will be understood that the degree of rigidity and extensivity of the core elements of the present invention i. e. the fillet 4,21 and the fabric 1,26 and the sealing tape 8,27 may be varied in order to achieve desired performance. For example the fabric 1,26 may be made of a non-woven felt to facilitate good curable impregnant uptake whilst the fillet 4,21 may be made of a woven material or include a resilient scrim to provide the pipeliner with some structural integrity and finally the sealing tape 8,27 may have a high degree of elasticity in order to ensure a good environmental seal is provided about the joint between edges 2,3; 24,25 even though there may be some damage to such joint as a result of the trauma of installation and/or impregnation with a curable resin. With the fillet 21 the base strip 22 may be formed of one particular fabric type whilst the ribbon 23 may be formed of a different fabric type so the strip 22 may include a resilient scrim whilst the ribbon 23 has a more deformable but more impregnant receptive nature.

It will be understood that in addition to a simple straight ribbon 23 in fillet 21 it may be possible to provide interlocking castellation between the edges 24,25 and an appropriately configured ribbon with the result that an improved bond strength may be achieved and the longitudinal stitch path through the castellations interlocked with one another may be achieved.

A final and potentially advantageous embodiment of the present invention would have the joint secured simply through adhesion of the mesa section 7,23 flat to the tape 8,27. The shoulder areas of the fillet and the longitudinal edges being unsecured other than through abutment.

Thus, the strength of the joint is determined by the tape 8,27 and any bonding between the mesa 7,23 and the edge faces of the fabric. In such a configuration, stress can be readily relieved and so the potential for bond rupture deminished.