WO2000028257A1

WO2000028257A1 - Repairing material for flow channels

Info

Publication number: WO2000028257A1
Application number: PCT/FI1999/000929
Authority: WO
Inventors: Seppo JÄRVINEN
Original assignee: Suomen Putkisaneeraus Oy
Priority date: 1998-11-06
Filing date: 1999-11-08
Publication date: 2000-05-18
Also published as: FI982416A0; FI982416A; AU1274200A

Abstract

A flow conduit repairing material is a tube formed of a flexible felt made of fibres, the felt being impregnated with a hardenable agent. The felt forming the tube is left unreinforced with a reinforcement textile, and the reinforcement is achieved at least by bonding between the fibres by means of a binder agent, e.g. by thermal bonding by means of solid particles, such as binder fibres. The slope of a graph showing force as a function of elongation in the elongation range from 0 to 10 % is greater in the machine direction than in the transverse direction.

Description

Repairing material for flow channels

The present invention relates to a flow conduit repairing material set forth in the preamble of claim 1 for repairing flow conduits, such as pipe lines.

The repair work of old, deteriorated pipe lines with a purpose of fixing cracks and fissures developed in the pipes is currently generally effected by using a flexible material to be laid on the inner surface of pipes, said material including a hardenable agent as well as a necessary reinforcement layer for providing strength during the installation. Such material is generally laid in underground pipe lines from above the ground as a long tubular sleeve in a manner that the pipes need not be dug up. Such a method, known for example under the name "Insituform" or "Paltem", is in a wide-spread use.

The material inserted inside a pipe line is required to have a particularly good flexibility, deformability and strength and, thus, it has been difficult to find proper materials. In addition, since pipes exist in varying sizes and often include sharp bends, flexibility and deformability are particularly important factors in a lining and repair material. Conventional reinforcement materials, such as e.g. a woven fabric, a staple fibre mat, and reinforcement filaments extending in the longitudinal direction, are not suitable for the method in question, because they restrict the deformability of the repair blank in the longitudinal direction of the pipe, which is needed at the stage of installing the blank.

For example, European application publication 0 392 026 presents reinforcement layers, in which the filaments are formed into uniform textiles, such as a woven fabric, a knitted fabric, or a braiding with a directional reinforcement effect. A similar problem is present in the solution of US patent 4,576,205, in which a fabric forming a basic reinforcement is provided with threads threaded around the warp threads. Furthermore, European application publication 0 278 466 discloses a uniform woven structure containing filaments which together with the woven structure accomplish a directional reinforcement effect.

Repair materials equipped with reinforcement textiles and having the form of a tubular sleeve are also known from Finnish patent 88646, to which corresponds European patent 0 523 090, as well as from Finnish patent 92570.

It is an aim of the invention to present a material with good flexibility as required by various pipe sizes, and a good reinforcement effect in all directions as required at the installation stage. The material to accomplish the invention is characterized in what will be presented in the characterizing part of the appended claim 1.

The invention is based on the observation that using an unreinforced felt and suitable binding of fibres, optimal properties are achieved when tubular repair materials of felt are used particularly for repairing un- pressu zed flow conduits (sewage pipes, water pipes).

In the following, the invention will be described in more detail with reference to the appended drawings, in which

Fig. 1 illustrates the use of a material according to the invention,

Fig. 2 illustrates the repair material according to the invention in a sectional view perpendicular to its plane,

Fig. 3 illustrates the strength values of the repair material, and

Figs. 4a and 4b illustrate ways of using the repair material in a cross- sectional view perpendicular to the flow conduit.

Figure 1 shows the use of the material according to the invention. A tubular continuous sleeve is inserted into a flow conduit 1 placed in the ground, such as e.g. a water-supply pipe or a sewage pipe, in such a way that its one open end is fixed with a hoop or the like 3' around the mouth of a particular guide pipe 3. The sleeve travels through the guide pipe in such a way that its outer surface, which comes against the tube to be actually mended, is as the inner surface inside the guide pipe, that is, the sleeve is, in a way, turned inside out. After this, a medium, such as a gas or a liquid, is used to push the sleeve 2 into the pipe 1 to be repaired, and the tubular sleeve is, thanks to its deformability, pressed at its outer surface against the inner walls of the pipe 1. At the final stage, the sleeve will be along its whole length inside a pipe section with a corresponding length as a tubular piece surrounding the inner periphery of the tube in the cross-sectional direction, after which the sleeve 2 is hardened by subjecting it to heat, e.g. by leading hot water or gas inside the sleeve. The hardening into an inner layer sealing the pipe is effected by a heat-setting resin, such as epoxy resin or unsaturated polyester, contained in the sleeve.

Figure 2 shows the structure of a repairing material according to the invention. The material 2 consists of a planar felt 5 with a substantially standard thickness, being a non-woven felt formed of fibres. The felt layer 5 is reinforced preferably by needling and heat-bonding; that is, the fibres are bound to each other mechanically in connection with the needling. The felt layer 5 can also be produced in such a way that the fibres are fed as a card mat or as a pre-felt on top of another pre-felt, after which the layers are subjected to needling and heat-bonding, to obtain a felt layer 5 reinforced by needling and heat-bonding.

For bonding of the fibres, it is, in principle, possible to use any suitable binder agent which can also act on another principle than by heat. In particular, the reinforcement is effected by thermal bonding by means of solid particles in the felt. These can be particularly fibrous, wherein they at least at the felt-forming stage are part of the fibrous structure of the felt.

By means of orientation of the fibres, anisotropism is obtained in the felt layer 5 in such a way that the felt has a certain stress-strain behaviour, which is particularly important in the elongation range from 0 to 10 %. Differences in longitudinal and transverse behaviour occur in this range, in this elongation range from 0 to 10 %, which is important from the use point of view, the slope of a curve showing force as a function of elongation is greater in the machine direction, e.g. at least 50 %, preferably at least 100 % greater than in the transverse direction.

For target values for the breaking force and the elongation at break can be given a breaking force of 40 — 150 %, preferably at least 50 — 140 % greater in the longitudinal direction than in the transverse direction, and an elongation at break of at least 40 %, preferably at least 50 % greater in the transverse direction than in the longitudinal direction. For the material to have sufficient strength, the tensile breaking strength in the transverse direction should be at least 800 N, but it is also possible to use materials having a value below said target value. The same applies to the tensile breaking strength in the longitudinal direction, which, according to target values, should be at least 900 N, preferably at least 1000 N. The grammage of the felt layer 5 must be sufficiently high, and it is preferably at least 600 g/m² without the impregnated agent, wherein the above-mentioned weight also refers to the total weight of the felt layer formed of different layers. It has been found that the felt in question, left unreinforced with a separate reinforcement textile layer, meets precisely the strength and stretching requirements necessary in the repair of unpressurized flow conduits. Stretching capacity in the transverse direction is significant as the tubular piece adapts to variations in the diameter and variations in the shape of the repaired pipe 1 in the direction of the diameter. The felt or pre-felt layers forming the basic structure of the felt layer 5 are made by forming a fibre mat of fibres onto a formation base by means of an air flow. In connection with the formation, the fibres are oriented in the direction of the plane of the felt in such a way that, seen in the direction of the plane, the felt is provided with said anisotropic properties. The machine direction of the mat formation is the axial direction, i.e. the longitudinal direction of the tubular piece to be produced, and the transverse direction is the peripheral direction of the tubular piece, and in view of the use, the above-mentioned values refer to properties of the tubular piece in the axial direction and in the peripheral direction.

As raw materials for the felt, it is possible to use heat-bondable synthetic fibres, particularly thermoplastic fibres. In particular, the fibrous raw materials for the felt are fibres which are thermally non-bondable at processing temperatures, with a suitable quantity, preferably 10 to 20 wt-% binder fibres admixed therein to be utilized for the thermal bonding. Such binder fibres are, at least on their surface, of a thermoplastic polymer which is converted into an adhesive state at the processing temperature. Such binder fibres used are preferably bicomponent fibres in which a part of the fibre remains unaltered and the part on the surface is converted to an adhesive state by the effect of the temperature. An example of such bicomponent fibres are PET/CoPET fibres, in which the unchangeable part is of polyester and the changeable part is of copolyester.

The following table shows some manufactured felts and their properties. The pre-felts of samples 1 and 2 were subjected to thermal bonding at a temperature of 130...140°C, after which they were needled together. In samples 3 and 4, the thermal bonding was performed on a felt formed of layers needled together.

Table. Examples of manufactured felts. Fibre compositions 85 % PET / 15 % Kanebo 4080 bicomponent fibre (PET/CoPET)

Sample 1 Sample 2 Sample 3 Sample 4

Way of needling needling of needling of needling of a pre-felt and a two pre-felts two pre-felts card mat together together together

Heat-bonding (°C) 135 139

Grammage (g/m²) 582 744 638 744 (SFS 3/92)

Thickness (mm) (Edana 30,3-78) 0,1 kPa, mean 6,0 6,7 6,7 6,6

- minimum 5,8 6,3 6,3 6,1

- maximum 6,8 7,1 6,7 7,0 0,5 kPa, mean 5,4 5,9 6,0 5,8

- minimum 5,0 5,5 5,7 5,3

- maximum 5,9 6,2 6,2 6,2

Breaking force (N)

(Edana 20.1-73)

- in the machine direction 1219 1848 1708 1830

- in the transverse direction 602 1085 792 962

Elongation at break (%)

(Edana 20.1.-73)

- in the machine direction 67 61 49 46

- in the transverse direction 113 98 118 106

Fibre content (Volume-%) 7,8 9,1 7,7 9,3 (calculated on the basis of thickness and grammage obtained at 0,5 kPa)

Depending on the apparatus, it is possible to manufacture felts having a greater grammage than those presented in the table, directly from a card mat.

Figure 3 shows strength values of the repairing materials measured in the longitudinal direction (graphs A) and in the transverse direction (graphs B) of the felt, and corresponding values of a known commercial felt are presented by graphs A0 and B0. As indicated by the graphs, in the elongation range from 0 to 10 %, the slopes of the linear initial portions of the graphs are greater in the machine direction (A) than in the transverse direction (B). The slopes are at least 50 %, preferably at least 100 % greater in the machine direction. Similarly, the graphs indicate that the force values measured at the elongation level of 10 % are greater in the machine direction than in the transverse direction, and for each pair of graphs, the values are at least 50 % greater in the machine direction. The values are preferably at least 100 % greater in the machine direction.

The material also comprises a thin surface layer 4 which is placed on the surface of the repairing material and which is indicated with a bro- ken line in the figures. The surface layer 4 can be applied onto the outer surface formed by the felt layer 5 for example by hot calendering. The layer 4 can be of a material previously used in corresponding materials, having sufficiently good stretchability and wear resistance, such as polyurethane, which will face the inner part of the flow conduit and insulate the other layers from the same.

The above-mentioned strength values indicate the strength values of the felt layer 5 without a coating. On the other hand, the coating, which is only a thin layer bound to the surface fibres, does not substantially affect the strength of the felt in use. In the installation, the strength properties of the felt and the strength of the coating act jointly.

A heat-setting resin, such as epoxy resin or unsaturated polyester resin, can be impregnated in the material for example just before the use by impregnating the felt layer 5 with said substance. A flowing substance is well absorbed in between the fibres.

The tubular sleeve formed by the repairing material can be manufactured of a continuous elongated fibrous felt made in the above- mentioned way for example by seaming a planar blank at its side edges.

Figure 4a shows a repair material located in the shape of a tube inside a flow conduit 1. Figure 4b shows an alternative use of the repairing material, according to which the repairing material can be used to give some mass between a conventional felt 6 equipped with a reinforcement textile 6a and the wall of a flow conduit 1. In this case, no surface layer 4 will be needed in the felt 5. The grammage of the felt used as the filler felt 5 depends on the amount of mass that is needed.

The invention is not limited solely to the embodiments presented in the above description and in the appended drawings, but it can be modified within the scope of the inventive idea presented in the claims. The material can also consist of shorter tubular pieces which are placed inside a pipe to be repaired, and the strength, stretchability and deformability of the material in the correct directions can thus be util- ized. Thanks to the anisotropic properties of the felt, the material is, however, particularly suitable to be used inside a long tubular flow conduit as a repair material turned inside out, because in this connection, its above-mentioned properties can best be utilized.

Claims

Claims:

1. A flow conduit repairing material which is a tube formed of a flexible felt made of fibres, the felt being impregnated with a hardenable agent, characterized in that the felt forming the tube is left unreinforced with a reinforcement textile, and the reinforcement is achieved at least by bonding between the fibres by means of a binder agent, e.g. by thermal bonding by means of solid particles, such as binder fibres.

2. The material according to claim 1 , characterized in that the slope of a graph showing force as a function of elongation in the elongation range from 0 to 10 % is greater in the machine direction than in the transverse direction.

3. The material according to claim 2, characterized in that the slope of the graph in the elongation range from 0 to 10 % is at least 50 %, preferably at least 100 % greater in the machine direction than in the transverse direction.

4. The material according to any of the preceding claims, characterized in that the breaking force is greater in the longitudinal direction than in the transverse direction of the tube and the elongation at break is smaller in the longitudinal direction than in the transverse direction of the tube.

5. The material according to claim 4, characterized in that the breaking force is 40 to 150 %, preferably at least 50 to 140 % greater in the longitudinal direction than in the transverse direction and the elongation at break is at least 40 %, preferably at least 50 % greater in the transverse direction than in the longitudinal direction.

6. The material according to any of the preceding claims, characterized in that the tensile breaking strength is at least 800 N in the transverse direction.

7. The material according to any of the preceding claims, characterized in that the tensile breaking strength is at least 900 N, preferably at least 1000 N in the longitudinal direction.

8. The material according to any of the preceding claims, characterized in that the content of the binder fibre used in thermal bonding is 5 to 40 wt-%, preferably 10 to 20 wt-% of the fibrous raw material of the felt.

9. The material according to any of the preceding claims, characterized in that the binder fibre is a bicomponent fibre, such as PET/CoPET fibre.

10. The material according to any of the preceding claims, character- ized in that the structure of the felt is reinforced by needling in addition to thermal bonding.

11. The material according to any of the preceding claims, characterized in that the felt is formed by a dry method of fibres brought with an air flow onto a formation base.