AU3740193A - Apparatus for use in repairing a pipeline and method for carrying out such repairs - Google Patents

Description

APPARATUS FOR USE IN REPAIRING A PIPELINE AND METHOD FOR CARRYING OUT SUCH REPAIRS

This invention relates to apparatus used in the process of refurbishing damaged conduits, pipelines and sewer pipes through the application of a reinforced lining to their inner walls by means of an inflatable form.

The refurbishment of cracked, broken or eroded pipelines or sewer pipes through so-called soft lining methods involving the application of a reinforced lining to their inner walls is well known in the art. Two principal methods are employed : the eversion of a tube of thermosetting resin - impreg ,/ ed reinforcement fabric into a section to be reiined from an external position by means of a head of water, and the application of a layer of thermosetting resin - impregnated reinforcement material to the inner walls of a section to be reiined by means of a form inflatable by air or water pressure. In both cases, curing of the thermosetting resin may be accelerated by circulation of hot water, steam through said inflatable form.

A shortcoming exists in the second method described in which an inflatable form is employed in that, particularly with repeated use, the external material of the form may develop an affinity for the resins employed in the relining process and may thus bond to the new lining. This renders difficult the stripping and removal of the form after curing of the resins. It is of course possible to provide a separate layer or sheath between the resins and the external surface of the inflatable form to prevent the form being adhered to the resins, however, in the prior art such separate layers have been secured in some way to the inflatable form so that they can be withdrawn from the pipe being repaired. Such layers cannot be left in the pipeline as they may eventually become detached and ultimately form a blockage in the pipeline. On the other hand, if the layer is secured to the inflatable form, it creates the same removal difficulty that existed with the inflatable form without such a layer and therefore only serves to protect the inflatable form. The present invention aims to provide apparatus for the refurbishment of pipelines and sewer pipes through the application of a layer of thermosetting resin - impregnated reinforcement material to their inner walls by means of an inflatable form which may be readily and reliably stripped from a refurbished section and which embodies a coaxial duct capable of sustaining a flow of liquid through the form whilst it is in use.

According to a first aspect of the present invention, there is provided apparatus for applying in situ a repair material to a repair zone of an inner wall of a conduit, said apparatus for applying in situ a repair material to a repair zone of an inner wall of a conduit, said apparatus comprising a radially expandable device in use to extend over a predetermined axial length of the conduit to be repaired and over at least a part of the inner circumference of said conduit, said radially expandable device having an outer surface means forming an outer wall of an expandable cavity, means for supplying a pressure medium to said expandable cavity or withdraw said pressure medium from said expandable cavity to either move said outer surface means radially outwardly or to move said outer surface means radially inwardly, and a flexible sheath member separate from said radially expandable device and arranged so as to be capable of forming an outer layer extending along and at least partially circumferentially around said radially expandable device, in use, between said repair material and said outer surface means, and withdrawal means connected to said sheath member adjacent one end whereby said sheath member can be removed from said conduit with at least a portion of the sheath member contacting said repair material everting as the sheath member is moved axially along said conduit. Conveniently the radially expandable device may include a core member which can include a through flow passage. The core member and said withdrawal means for removal of said flexible sheath member together with said flexible sheath member are by means of the present invention thus adapted for independent withdrawal from said conduit by virtue of the fact that the flexible sheath member is independent of said core member. Alternatively, if it is desired to remove both the radially expandable device and the flexible sheath member simultaneously, the means for removal of said flexible sheath member may be adapted so as to withdraw or be withdrawn by the radially expandable device. In either case, the arrangement of the flexible sheath member enables it to be peeled away from the repair material by at least partial eversion when the radially expandable device and/or the flexible sheath member is withdrawn along the pipeline without affecting the bond between the repair material and the pipeline wall.

In an alternative form of the invention, the flexible sheath member comprises inner and outer layers, the inner layer being connected to the means for removal of the flexible sheath member and to the outer layer at ends of the inner layer which are axially remote from each other.

Preferably, the means for removal of the flexible sheath member and the core member of the apparatus are coaxial and define an axially extending passage so as to permit flow through the conduit whilst the apparatus is in use.

Conveniently, the means for removal of the flexible sheath member defines an annuius.

In this embodiment of the invention, the radially expandable device may comprise an inflatable element defining an annular or part annular enclosed space extending axially along the core member. Inflating medium inlet/outlet means may be provided internally of said core member so as to enable inflation and deflation of the inflatable element.

According to a second aspect of the invention, a method of applying a repair material in situ to a repair zone of an inner wall of a conduit to be repaired, said process comprising: providing a radially expandable device adapted in use to extend over a predetermined axial length of the conduit to be repaired and over at least part of the inner circumference of said conduit, said radially expandable device having an outer surface means forming an outer wall of an expandable cavity, means for supplying a pressure medium to said expandable cavity or withdrawn said pressure medium from said expandable cavity; providing a flexible sheath member, separate from said radially expandable device, over said outer surface means with withdrawal means enabling withdrawal of said sheath member from the conduit means; providing a structural repair material outwardly of said sheath member; moving said radially expandable device with said sheath member and repair material into said conduits to be repaired and thereby positioning said repair material adjacent the repair zone; introducing a pressure medium to said expandable cavity to move said outer surface means radially outwardly to press said repair material against said repair zone; subsequently withdrawing said pressure medium from said expandable cavity to move said outer surface radially inwardly; and withdrawing said radially expandable device from said conduit, said flexible sheath member being removed from said conduit either simultaneously with said radially expandable device or separately therefrom with at least a portion of said sheath member contacting the repair material everting as the sheath member is moved axially along said conduit during removal.

In a preferred method, according to this aspect of the invention, the radially expandable device and said flexible sheath member together with said means for removal of said flexible sheath member are withdrawn simultaneously or sequentially from said conduit by moving the radially expandable device and the means for removal of the flexible sheath member simultaneously or sequentially along the conduit in a direction towards an axial end of said flexible sheath member opposite to an end connected to said withdrawal means for removal of said flexible sheath member. in an alternative embodiment of this aspect of the invention, there is provided a method wherein said flexible sheath member comprises an inner and outer layer, said inner layer being connected to said means for removal of said flexible sheath member and to said outer layer at ends of said inner layer axially remote from each other, said radially expandable device and said flexible sheath member together with said means for removal of said flexible sheath member being withdrawn from said conduit in a manner such as to allow the flexible sheath member to be peeled away from said repair material by at least partial eversion. Preferably the radially expandable device comprises an inflatable element defining an annular or part annular enclosed space forming said expandable cavity, extending axially along said core member.

In a further preferred embodiment of this aspect of the invention, fluid is directed into said inflatable element so as to radially expand it. Conveniently the fluid is heated and the repair material includes a thermosetting material or substance.

Various preferred aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which :

Figure 1 is a longitudinal cross-sectional view of an inflatable form according to the invention in situ in a pipeline to be repaired.

Figure 2 is a longitudinal cross-sectional view of an inflatable form according to a second embodiment of the invention in situ in a pipeline to be repaired.

Figure 3 is a longitudinal cross-sectional view of the inflatable form of Figure 1 in an inflated condition in situ in a pipeline being repaired.

Figure 4 is a longitudinal cross-sectional view of a repaired pipeline from which a flexible sheath member is to be removed by eversion. With reference to Figure 1, an inflatable form (1) is made by forming an inflatable element (2) axially along and circumferentially around a core member

(3). The inflatable element is fixed at its ends (2a and 2b) to the core member

(3). Inlet/outlet duct (4) is provided through said core member (3) and into said inflatable element (2) to enable an inflating medium to be delivered to and withdrawn from the inflatable element (2). The inflatable form (1) is also provided with a separate flexible sheath (5) which is connected to means for its removal (6) in the form of an annuius at one axial end of the core member (3).

The separate flexible sheath (5) is located axially along and circumferentially around the inflatable element (2) located externally of the core member (3). The fact that the flexible sheath (5) is separated from the core member (3) and inflatable element (2) enables it to be withdrawn from the pipeline independently of the core member (3) and inflatable element (2) if so desired. However, it is also possible, if the means for removal of the flexible sheath is of substantial enough form, that the two parts could be removed simultaneously.

With reference to Figure 2, a second embodiment of the invention is illustrated in which the flexible sheath (5) comprises an inner layer (5a) and an outer layer (5b). The inner layer (5a) is connected to the means for removal of the flexible sheath (6) and to the outer layer (5b) at ends of the inner layer (5a) axially remote from each other. This embodiment merely enables an alternate orientation of the inflatable form which may be more convenient than the embodiment of Figure 1, depending on the orientation of the pipeline to be repaired.

In use, repair material in the form of a sheet or tube of reinforcement material (7) impregnated with thermosetting resin is placed over the inflatable form (1). The whole assembly including the core member (3) with attached inflatable element (2) and the separate flexible sheath (5) together with the means for removal of the flexible sheath (6) is then simultaneously introduced into the section of a pipeline or sewer pipe required to be refurbished. The apparatus may be oriented according to either Figures 1 or 2. Correct positioning may be verified through the use of closed circuit television. Referring to Figure 3, an inflation medium at a suitable temperature and pressure is then introduced through inlet/outlet duct (4) causing the inflatable element (2) to expand and force the resin - impregnated reinforcement material into intimate contact with the inner wall surfaces of the pipeline or sewer pipe. The inflating medium circulates at a suitable pressure and temperature and is preferably continued until full curing of the resin of the resin - impregnated reinforcement material is obtained. Conveniently, the inflating medium might be water, air or some other suitable gas or fluid.

Following full curing of the thermosetting resin with which the reinforcement material is impregnated, inflating medium circulation is stopped and the inflatable elements (2) are deflated by removal of the inflating medium from the apparatus. The inflatable form (1) include the core member (3) and the inflatable element (2) is then withdrawn from the pipeline or sewer pipe section. If the core member (3) is to be withdrawn independently and before the flexible sheath (5) and the means for removal of the flexible sheath (6) withdrawal should occur in an axial direction away from the means for removal of the flexible sheath (6). Referring to Figure 4, when withdrawal of the core member (3) and inflatable element (2) occurs independently of the flexible sheath (5), withdrawal of the latter occurs subsequent to withdrawal of the former and is conducted so that the flexible sheath everts and peels cleanly away from the reinforcement material (7). In this way, as the inflatable form exits the section which has been refurbished, it is, more or less, completely everted. This peeling action has been shown to be extremely efficient at overcoming any residual adhesion between the flexible sheath and the resin with which the reinforcement material is impregnated.

Alternatively, the flexible sheath (5), means for removal of the flexible sheath (6) and the inflatable form (1) comprising core member (3) and inflatable element (2), may be withdrawn from the pipeline simultaneously. In this instance, it is necessary that, according to the embodiment of Figure 1, the means for removal of the flexible sheath be of sufficient size to bear the force required to withdraw the core member (3) and inflatable element (2). Again, however, simultaneous withdrawal of the core member (3), inflatable element (2), flexible sheath (5) and means for removal of the flexible sheath (6) must be in a direction such that the flexible sheath (5) is caused to evert thus peeling away from the resin impregnated reinforcement material as previously described.

In another alternate withdrawal method which may be used with respect to the embodiment of Figure 2, the flexible sheath (5) and means for removal of the same (6) may be carefully withdrawn prior to withdrawal of the core member (3) and the inflatable element (2). Care must be taken to ensure that eversion of the flexible sheath (5) occurs such that it is peeled away from the resin impregnated reinforcement material.

Claims (9)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. Apparatus for applying in situ a repair material to a repair zone of an inner wall of a conduit, said apparatus comprising a radially expandable device adapted in use to extend over a predetermined axial length of the conduit to be repaired and over at least a part of the inner circumference of said conduit, said radially expandable device having an outer surface means forming an outer wall of an expandable cavity, means for supplying a pressure medium to said expandable cavity or withdraw said pressure medium from said expandable cavity to either move said outer surface means radially outwardly or to move said outer surface means radially inwardly, and a flexible sheath member separate from said radially expandable device and arranged so as to be capable of forming an outer layer extending along and at least partially circumferentially around said radially expandable device, in use, between said repair material and said outer surface means, and withdrawal means connected to said sheath member adjacent one end whereby said sheath member can be removed from said conduit with at least a portion of the sheath member contacting said repair material everting as the sheath member is moved axially along said conduit.

2. Apparatus according to Claim 1 wherein said outer surface means of the radially expandable device extends circumferentially around said device, said sheath means being formed as a tube separate from said radially expandable device.

3. Apparatus according to Claim 2 wherein said tube includes at least one circumferential fold with only an outer surface part of said tube being arranged to contact said repair material.

4. Apparatus according to anyone of Claims 1 to 3 wherein said radially expandable device includes a core member.

5. Apparatus according to Claim 4 wherein said core member extends axially between opposed axial ends of the radially expandable device, said core member having a central through flow passage to maintain flow in said conduit during a repair operation.

6. Apparatus according to any one of Claims 1 to 5 wherein said radially expandable device includes positioning means for locating said device at said repair zone and removal means for removing said device from said conduit.

7. Apparatus according to Claim 6 wherein said withdrawal means connected to said sheath member forms part of said removal means.

8. Apparatus according to Claim 6 wherein said withdrawal means connected to said sheath member is operable independently of said removal means.

9. A method of applying a repair material in situ to a repair zone of an inner wall of a conduit to be repaired, said process comprising; providing a radially expandable device adapted in use to extend over a predetermined axial length of the conduit to be repaired and over at least part of the inner circumference of said conduit, said radially expandable device having an outer surface means forming an outer wall of an expandable cavity, means for supplying a pressure medium to said expandable cavity to withdraw said pressure medium from said expandable cavity; providing a flexible sheath member, separate from said radially expandable device, over said outer surface means with withdrawal means enabling withdrawal of said sheath member from the conduit; providing a structural repair material outwardly of said sheath member; moving said radially expandable device with said sheath member and repair material into said conduit to be repaired and thereby positioning said repair material adjacent the repair zone; introducing a pressure medium to said expandable cavity to move said outer surface means radially outwardly to press said repair material against said repair zone; subsequently withdrawing said pressure medium from said expandable cavity to move said outer surface radially inwardly; and withdrawing said radially expandable device from said conduit, said flexible sheath member being removed from said conduit either simultaneously with said radially expandable device or separately therefrom with at least a portion of said sheath member contacting the repair material everting as the sheath member is moved axially along said conduit during removal.