GB1601234A - Materials for lining passageways - Google Patents

Description

(54) IMPROVEMENTS RELATING TO MATERIALS FOR LINING PASSAGEWAYS (71) We, INSITUFORM (PIPES & STRUCTURES) LIMITED, a British Company of 12B Station Road, Ince, Nr. Chester, Cheshire, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to the lining of passageways and to the production of materials for use in methods of lining passageways. By the expression, "passageways", as used herein is intended to mean the bores of ducts, pipes and channels, which may be above or below ground, as well as underground tunnels, passages, sewers and shafts.

In our British Patent No. 1,357,355 it is disclosed that in order to line a passageway, a tubular lining structure is formed comprising an inner impermeable membrane, a layer of resin absorbent felt material, and an outer impermeable membrane. The felt material is thoroughly impregnated with resin and in the process, before the resin has had sufficient time to cure, the tubular structure is inflated by any suitable fluid such as gas or liquid, against the surface to be lined, and it is held in this position whilst curing is effected. The resin when cured forms a hard self-supporting rigid liner, and the inflating pressure can be removed leaving the lining in situ. In this Patent it is disclosed that the tubular liner is inserted into the passageway by any suitable means.

In British Patent No. 1,499,455, there is disclosed a particular method for the insertion of an impregnated tubular liner which facilitates the handling of same. It is to be appreciated that when a tubular liner having a resin absorbent felt is in the condition in which the felt is thoroughly soaked with resin, it is an extremely heavy article, especially if it is of long length e.g. of the order of two or three hundred metres. In the said British Application, there is disclosed that the tubular liner can be inserted by anchoring one end of the liner, and by everting the liner into the passageway using a liquid. The liquid serves two functions, it inflates the everted liner against the passage to be lined and maintains it in such condition, and secondly the portion of the liner which is passing through the already everted portion is buoyantly supported by the liquid, ensuring that the heavy liner as it is passing into the already everted portion of the liner will not frictionally drag along the already everted portion. In this connection, it is also possible to include in the liquid a lubricant such as a soap in order to facilitate slippage of the impregnated liner into the passageway.

The practise heretofore for constructing liners of the type described above, is to form a separate tube of the resin absorbent material and a separate tube of the inflating membrane material. The adoption of this practise had led to difficulties for a number of reasons.

Firstly, and most obviously, it is a difficult procedure to insert a very long tube into another long tube, and as the eversion technique as outlined above is used in the majority of applications, it is necessary for the resin absorbent material to be put inside the separate membrane which is of course more difficult than inserting a light flexible membrane into the heavier and less flexible and thicker resin absorbent material.

Secondly, because in practise separate tubes have been used to form the lining, there is a possibility that air pockets can form between the two tubes of resin absorbent material and membrane, even although the resin absorbent material is soaked with the curable resin, and the presence of these air pockets can create problems when the eversion technique as outlined above is used.

The use of particular materials for the resin absorbent material and the membrane or membranes, causes particular problems.

Thus, when installing a lining using a polyester resin impregnated felt and a separate inflation membrane of the polyurethane film "Tuftane" (Registered Trade Mark), which has good strength properties and is sufficiently elastic to accommodate the stretch necessary in the lining so that it will conform to the variations in section that normally obtain, the polyurethane film "Tuftane" (Registered Trade Mark), like other elastomeric materials tried degraded upon exposure to the styrene in the polyester resin to the extent that it was not reusable, because it does not bond to the felt; it is removed after each installing method and discarded. Since the cost of the film is high e.g. of the order of 7.4 U.S. dollars per M2 this has resulted in a very material cost consideration.

Finally, with the liners as used in production, it is necessary to form separate seams in the membrane and resin absorbent material.

With these problems in mind, the present invention aims at the production of a lining material suitable for use in the methods outlined above, and suitable in particular for use in the eversion method outlined above.

In accordance with the present invention there is provided a method of manufacturing a tubular lining material, wherein a resin absorbent felt in tubular form is coated with a fluent composition which bonds or anchors to the outside surface fibres of the resin absorbent felt, leaving the body of the felt free to absorb synthetic resin, and which sets so as to form a fluid impermeable membrane.

The coating may be applied by anyone or several of the following: calendaring, spraying, dipping, painting and may be applied in a number of layers in order to build up a membrane of the requisite thickness, each layer being cured by heating after its application if desired.

In the preferred form the method includes the step of forming the needled felt into a tube, for example, by winding a web of felt on a mandrel and securing together the overlapped portions, and as the tube is fed from the mandrel, it may be coated with the coating material to form the membrane. If a number of layers of coating are to be applied, there may be a number of application stations arranged in sequence. After the application of the coating material, or each layer of the coating material, it may be subjected to a heat treatment in order to effect cure thereof.

By applying the coating material in liquid or paste form, one achieves the avoidance of having seams in the lining material membrane.

In one preferred arrangement, a tube of resin absorbent felt is caused to pass down through a circular applicator, defining a well in which is contained the quantity of the coating medium in paste or liquid form so that the outer surface of the absorbent material tube wipes against the coating material in the well, thereby forming a layer on the downward travelling absorbent material.

In another example, a spraying head applies the coating material to overlapping layers of felt material secured together to form a tubular construction and the spraying head is caused to rotate around the tubular, formed structure.

In another arrangement, the felt material is formed into a tubular structure by being fed to a rotating mandrel at an angle, so that the turns of felt material overlap, and where they overlap the turns are bonded or stitched together, and then the coating material is applied to the outside of the thus formed tubular structure of felt material by one of the aforesaid methods or by transfer application from a carrier belt, and as the formed coated lining comes off the end of the mandrel, it is laid in a rotating container in order to neutralise the twist which would be imparted thereto as a result of rotation with the mandrel.

In another application, the felt tube may simply be dipped into a bath of the coating material and then removed therefrom, so as to take up a layer on the outside of the absorbent felt.lent felt.

The absorbent felt can be impregnated with the resin by the injection into the interior of the lining of a quantity of resin, and by working the resin along the length of the tube, for example by the use of squeeze rollers.

Embodiments of the present invention will now be described by way of example, with reference to the accompanying diagrammatic drawings, wherein: Fig. 1 illustrates, in perspective view, how a tubular structure can be formed from a flat web of resin absorbent felt; Fig. 2 illustrates one method showing how the tubular structure of Fig. 1 may be coated by dipping; Fig. 3 illustrates another method for the continuous formation of a tubular structure of resin absorbent felt and for the coating thereof; Fig. 3A illustrates a modified method of applying the coating; Fig. 4 illustrates another method of coat ina tubular resin absorbent felt; Fig. 5 illustrates another method of forming a tubular structure of resin absorbent felt from a web thereof, the Figure also illustrating how the tubular structure formed is coated; Fig. 6 is useful for explaining the method illustrated in Fig. 5; Fig. 7 is an enlarged sectional elevation showing a part of felt tube with a coating applied thereto; and Fig. 8 illustrates a method of applying the lining material to the passageway.

Referring first to Fig. 7, this figure illustrates a resin absorbent felt 10 to which has been applied a coating 16 in liquid or paste form, such coating being of a material which sets or can be set by heat to form a fluid impermeable membrane and also sets so as to be bonded to or mechanically anchored to the fibres of the felt material surface, whilst leaving the felt free to absorb a curable resin for the subsequent application of the material to a surface to be lined, as will be explained hereinafter.

The present invention is concerned with the production of a tube of the material illustrated in Fig. 7, and an example of how a tubular lining may be installed is given hereinafter.

In the invention a coating material 16 is applied to the ouside of a needled felt tube 10, the coating material is applied in liquid or paste state so as to form a thin film 16 on the outside of the felt 10. The coating may be applied under heat and pressure so as to form the composite material illustrated in enlarged detail in Fig. 7.

To use the coated tubular material, the felt 10 is thoroughly impregnated with a curable resin to the extent that it becomes completely embedded in the resin, and whilst the resin is still wet i.e. before it cures, the lining is applied to the passageway to be lined, the membrane 16 serving as a means whereby the tubular lining can be inflated, using gas or liquid against the surface to be lined.

Fig. 8 shows how a tubular coated felt produced as described above and having the felt impregnated with resin can be applied to a passageway surface to form a passageway lining in that it is so shaped whilst the felt 10 is impregnated with the resin as above described and is held in this position against the passageway until the resin cures, when the pressure applied, by a fluid, may be removed and the ends of the tubular lining trimmed off. With the setting of the resin, the lining becomes a free standing insitu lining having the membrane 16 forming a smooth inner surface thereto, and the resin absorbent felt lending impact strength to the lining as a whole.

In the arrangement shown in Fig. 8, the tubular lining is everted into the passageway as shown by anchoring one end of the lining and by filling the everted portion of the lining with liquid which buoyantly supports the heavy, resin impregnated lining as it passes along the inside of the already everted portion of the lining. In this regard, the liquid chosen is so related to the specific gravity of the lining including the resin that the lining is buoyantly supported and out of contact with the already everted portion of the tube.

This is important, because the linings according to the invention when impregnated with resin are extremely heavy and difficult to handle and were it not for the lending of the buoyant support to the lining by the liquid, it would be impossible to insert linings impregnated with resin which are of the length required e.g. of the order of two or three hundred metres.

It is possible in some cases to impregnate the resin absorbent material 10 with resin as it is everting inside the passageway, but it is still desirable to insert the lining using a liquid as above described.

A number of arrangements aim essentially at producing the material as illustrated in detail in Fig. 7 and for the purposes illustrated essentially in Fig. 8 and such arrangements are illustrated in Figs. 1-6.

In Fig. 1 it is shown how a flat web 30 of felt material can be formed into a tubular structure 32 by having the longer tubular edges overlapped as indicated at 34 and such edges are secured together with a connecting apparatus 36. In Fig. 2, it is shown how the tubular structure 32 formed as illustrated in Fig. 1, is coated with a coating medium 38 by being dipped in a bath of such medium and extracted vertically as shown in Fig. 2. Soon after the coated tubular structure 32 leaves the bath 38, it is passed into a heating apparatus 40 which serves to set the coating material to form the membrane for the inflation of the tubular lining during installation.

In the arrangement shown in Fig. 3, a reel of felt 42 is unrolled and wrapped around a mandrel 44 so that the turns of felt material overlap as shown, and the overlapped turns are connected together by the apparatus 46 which may stitch bond, fuse or adhesively connect the turns together. The connected turns therefore define a tubular structure of resin absorbent felt which moves in the direction of arrow 48 in Fig. 3 rotating at the same time, and the tubular structure passes a spraying head 50 from which is sprayed the coating material eventually to form the membrane. Although not shown, the thus coated tubular structure passes a heater which cures the coating material, and then the formed tubular lining is laid up in a rotating container for example container 52 so as to remove the twist in the tubular lining which arises by virtue of a rotation of the felt on the mandrel 44.

Instead of using a spraying head 50, the coating may be applied by transfer from a moving carrier, such as a belt. The coating will therefore be applied on a spiral winding and the overlapping coils will be sealed together.

Thus, as shown in Fig. 3A, in one form of transfer application, an endless band 46' has a layer of the coating applied to the top reach thereof, for example, by a doctor blade and the band 46' is pressed against tubular structure of felt whilst rotating on mandrel 44, as shown so that the coating material is transferred from the belt 46' to the felt to form the coating thereon.

In the arrangement shown in Fig. 4, the tube of felt 52 is caused to move upwardly in the direction of arrow 54 in Fig. 4 through a frusto-conical well 56 containing a quantity 58 of the coating composition, such that the upwardly travelling felt 52 picks up a layer of the coating material 60 on the outside thereof before passing through the heating apparatus 62 in order to set the material 60.

A supply tank for maintaining the level of coating material in well 56 is shown at 64 in Fig. 4. In a modification of this arrangement, the tube of felt moves downwardly.

In the arrangement illustrated in Figs. 5 and 6, a reel 66 of the felt material is rotated around a mandrel 68 and at the same time the resulting tubular structure of felt so formed is fed axially off the mandrel 68 as indicated by arrow 70 in Fig. 5, and at the same time a spray head 72 which is spraying coating material onto the outside of the tubular structure so formed, is rotated around the mandrel 68 as indicated by arrow 74 in Fig. 5. Although not shown in Figs. 5 and 6 there will again be a heater for setting the coating material.

In all of the processes above described, the coating step may be repeated in order to build up thicker layer of coating material or within the method, there maybe a plurality of stages of coating each followed by heating again to achieve the desired thickness of coating material.

In the arrangements of Figs. 3 and 5, the mandrel may be heated to effect or assist curing of the coating.

All of the tubular linings produced by the method illustrated in Figs. 1-6 are solely for use in connection with the method illustrated in Fig. 8, and normally the resin will be applied by injection into the interior of the lining and by passing the lining through squeezing rollers in order to ensure even distribution of the resin throughout the felt, before the lining is everted. In some cases it maybe possible to impregnate the felt material during eversion and in the passageway. The relationship between the coating material and the resin absorbent felt which is used must be such that the coating material bonds or mechanically anchors essentially to the surface fibres of the resin absorbent and does not penetrate the absorbent material too deeply which could impair its resin absorbent qualities. furthermore, the coating material should be selected so as not to react chemically and adversely with the resin when it is applied thereto.

The felt material may be of polyurethane, polypropylene or polyester felt.

The felt materials may be made up by laying thinner layers one on top of another and by needing the layers together.

As regards coating materials we have found that the polyurethane coating material known as "Tuftane" (Registered Trade Mark), is extremely suitable for use with polyurethane felts, but for polyester felts P.V.C. coating has been found to be suitable.

In a particular arrangement, the resin absorbent material is a polyester felt, and the resin is a polyester resin. The coating is of polyurethane or polyvinyl chloride liquid or paste composition. The felt tends to stabilize the polyurethane dimensionally and the polyurethane remains part of the installed lining. Applying the polyurethane as a coating also contributes to eliminating the pinhole effect which sometimes results, we believe, because the polyester fibre retains moisture which turns to steam during the exotherm of curing the resin. This effect is we believe also eliminated through the use of polypropylene fibre which has much less permeability than the polyester; the use of polypropylene felt is therefore preferred.

Another advantage of the coated material as compared to the separate tube arrangements of the prior art results when long lengths of lining are installed by eversion.

Polyurethane degradation shows up as a swelling of the material and when it is a free membrane it becomes longer than the absorbent material itself and can during eversion become gathered causing resin wrinkles on the surface of the lining.

Another benefit of the coated material is the significant increase in the strength of the material enabling the use of the higher heads of water or other liquid in the eversion process which contributes to increasing the length of lining possible in one operation.

In short, the coated material offers a significant reduction of the overall cost of material and simplified installation as all that is required to complete the installation to take the ends off and there is a minimum of material waste.

The thickness of the coating material would depend upon the application, but may for example in the range of 10-50 mils.

WHAT WE CLAIM IS: 1. A method of manufacturing a tubular lining material, wherein a resin absorbent felt in tubular form is coated with a fluent composition which bonds or anchors to the outside surface fibres of the resin absorbent felt, leaving the body of the felt free to absorb synthetic resin and which sets so as to form a fluid impermeable membrane.

2. A method according to Claim 1, wherein the coating is applied by at least one of the following processes, transferring, calendaring, spraying, dripping, painting.

3. A method according to Claim 1 or 2, wherein the coating is applied in a number of layers to build up a membrane of the requisite thickness.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   tube of felt 52 is caused to move upwardly in the direction of arrow 54 in Fig. 4 through a frusto-conical well 56 containing a quantity

   58 of the coating composition, such that the upwardly travelling felt 52 picks up a layer of the coating material 60 on the outside thereof before passing through the heating apparatus 62 in order to set the material 60.

   A supply tank for maintaining the level of coating material in well 56 is shown at 64 in Fig. 4. In a modification of this arrangement, the tube of felt moves downwardly.

   In the arrangement illustrated in Figs. 5 and 6, a reel 66 of the felt material is rotated around a mandrel 68 and at the same time the resulting tubular structure of felt so formed is fed axially off the mandrel 68 as indicated by arrow 70 in Fig. 5, and at the same time a spray head 72 which is spraying coating material onto the outside of the tubular structure so formed, is rotated around the mandrel 68 as indicated by arrow 74 in Fig. 5. Although not shown in Figs. 5 and 6 there will again be a heater for setting the coating material.

   In all of the processes above described, the coating step may be repeated in order to build up thicker layer of coating material or within the method, there maybe a plurality of stages of coating each followed by heating again to achieve the desired thickness of coating material.

   In the arrangements of Figs. 3 and 5, the mandrel may be heated to effect or assist curing of the coating.

   All of the tubular linings produced by the method illustrated in Figs. 1-6 are solely for use in connection with the method illustrated in Fig. 8, and normally the resin will be applied by injection into the interior of the lining and by passing the lining through squeezing rollers in order to ensure even distribution of the resin throughout the felt, before the lining is everted. In some cases it maybe possible to impregnate the felt material during eversion and in the passageway. The relationship between the coating material and the resin absorbent felt which is used must be such that the coating material bonds or mechanically anchors essentially to the surface fibres of the resin absorbent and does not penetrate the absorbent material too deeply which could impair its resin absorbent qualities. furthermore, the coating material should be selected so as not to react chemically and adversely with the resin when it is applied thereto.

   The felt material may be of polyurethane, polypropylene or polyester felt.

   The felt materials may be made up by laying thinner layers one on top of another and by needing the layers together.

   As regards coating materials we have found that the polyurethane coating material known as "Tuftane" (Registered Trade Mark), is extremely suitable for use with polyurethane felts, but for polyester felts P.V.C. coating has been found to be suitable.

   In a particular arrangement, the resin absorbent material is a polyester felt, and the resin is a polyester resin. The coating is of polyurethane or polyvinyl chloride liquid or paste composition. The felt tends to stabilize the polyurethane dimensionally and the polyurethane remains part of the installed lining. Applying the polyurethane as a coating also contributes to eliminating the pinhole effect which sometimes results, we believe, because the polyester fibre retains moisture which turns to steam during the exotherm of curing the resin. This effect is we believe also eliminated through the use of polypropylene fibre which has much less permeability than the polyester; the use of polypropylene felt is therefore preferred.

   Another advantage of the coated material as compared to the separate tube arrangements of the prior art results when long lengths of lining are installed by eversion.

   Polyurethane degradation shows up as a swelling of the material and when it is a free membrane it becomes longer than the absorbent material itself and can during eversion become gathered causing resin wrinkles on the surface of the lining.

   Another benefit of the coated material is the significant increase in the strength of the material enabling the use of the higher heads of water or other liquid in the eversion process which contributes to increasing the length of lining possible in one operation.

   In short, the coated material offers a significant reduction of the overall cost of material and simplified installation as all that is required to complete the installation to take the ends off and there is a minimum of material waste.

   The thickness of the coating material would depend upon the application, but may for example in the range of 10-50 mils.

   WHAT WE CLAIM IS: 1. A method of manufacturing a tubular lining material, wherein a resin absorbent felt in tubular form is coated with a fluent composition which bonds or anchors to the outside surface fibres of the resin absorbent felt, leaving the body of the felt free to absorb synthetic resin and which sets so as to form a fluid impermeable membrane.
2. 2. A method according to Claim 1, wherein the coating is applied by at least one of the following processes, transferring, calendaring, spraying, dripping, painting.
3. 3. A method according to Claim 1 or 2, wherein the coating is applied in a number of layers to build up a membrane of the requisite thickness.
4. 4. A method according to any preceding

   claim, including the steps of forming felt web into tubular form by winding on a mandrel so that the portions of the web overlap, and securing together overlapped portions of the web.
5. 5. A method according to any of claims 1 to 3, wherein the tube of resin absorbent felt is caused to pass down through a circular applicator. defining a well in which is contained the quantity of the coating medium in paste or liquid form, so that the outer surfaces of the absorbent material tube wipes against the coating material in the well, there by forming a layer on the downward travelling absorbent material.
6. 6. A method according to any of claims l to 3, wherein a spraying head applies the coating material to overlapping layers of felt material secured together to form a tubular construction and the spraying head is caused to rotate around the tubular, formed structure.
7. 7. A method according to any of claims 1 to 3, wherein the felt material in web form is formed into a tubular structure by being fed to a rotating mandrel at an angle, so that the turns of felt material overlap, and where they overlap, the turns are bonded or stitched together, and then the coating material is applied to the outside of the thus formed tubular structure of felt material and as this comes off the end of the mandrel. it is laid in a rotating container in order to neutralise the twist which would be imparted thereto as a result of rotation with the mandrel.
8. 8. A method according to claim 3 or 4.

   wherein the coating is transferred from a carrier to the outside of the tube.
9. 9. A method according to any of claims 1 to 3, wherein the felt tube is dipped into a bath of the coating material and then removed therefrom, so as to take up a layer on the outside of the absorbent material.
10. 10. A method according to any preceding claim, wherein a number of layers of coating are applied and there are a number of coating layer application stations arranged in sequence.
11. 11. A method according to any preceding claim, wherein the coating, or each layer of coating, after application to the resin absorbent felt, is subject to a heat treatment to set the material.
12. 12. A method according to any preceding claim, including the additional step of impregnating the resin absorbent felt with curable resin.
13. 13. A method according to claim 12, including introducing the resin into the interior of the lining and moving the lining relative to squeezing means which squeeze the resin evenly throughout the resin absorbent felt.
14. 14. A method of manufacturing a lining material, substantially as hereinbefore described with reference to any of the embodiments illustrated in the accompanying drawings.
15. 15. A lining manufactured in accordance with the method of any of the preceding claims.