WO2001077570A1

WO2001077570A1 - Repair bladder with breather vent

Info

Publication number: WO2001077570A1
Application number: PCT/US2000/009221
Authority: WO
Inventors: Nancy J. Marks
Original assignee: Flexfab Horizons International, Inc.
Priority date: 2000-04-07
Filing date: 2000-04-07
Publication date: 2001-10-18
Also published as: AU2000242083A1

Abstract

An inflatable bladder (10) for use in repairing a failure in a pipe. The inflatable bladder has an elongated, tubular body portion (12) defining a hollow interior with open ends and first and second end portions (14, 16). Each of the end portions closes one of the tubular body open ends. The bladder is made from a laminate of an inner (30) and outer (32) air-impermeable material with an electrically conductive intermediate layer (34) positioned therebetween. A vent (50) extends from the intermediate layer through one of the inner and outer layers to vent air from the intermediate layer.

Description

REPAIR BLADDER WITH BREATHER VENT BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an inflatable bladder comprising a heating layer encapsulated by one or more air impermeable layers for use in patching a broken underground pipe, and, more specifically, to an inflatable bladder having a breather vent for releasing air between the heating layer and the air-impermeable layers.

Description of the Related Art

Inflatable bladders are commonly used to repair breaks or cracks in underground pipes such as sewers. The inflatable bladder typically includes a leading and trailing conduit that is used to pull the bladder within the sewer and position it adjacent the failure in the sewer pipe. A patch material, typically comprising activated styrene, is temporarily affixed to the exterior of the bladder prior to positioning the bladder within the sewer. Once the bladder is properly positioned so that the patch is aligned with the pipe failure, the bladder is inflated through one or both of the leading and trailing hoses to press the patch against the failure in the pipe. The patch material is heated to a temperature great enough to affix/cure the patch to the pipe and seal the failure.

Current bladders typically comprise a laminate of opposing layers of air- impermeable material, preferably fluorosilicone, between which is positioned a carbon fiber mesh, commonly referred to as a carbon fiber sock, which is electrically conductive. The inflatable bladder terminates in opposing tapered ends on which are mounted end caps that close the ends of the bladder and couple the conduits to the sock. Electrical conductors, usually entrained about, forming part of, or contained within the conduits, electrically couple the carbon fiber sock to a source of electrical power. The application of electrical power to the carbon fiber sock generates heat, which heats the air-impermeable layers, resulting in a transfer of the heat to the patch to cure the patch to the sewer pipe. U.S. Patent Nos. 5,451,651; 5,648,137; and 5,656,231 all disclose conventional inflatable bladders for patching an underground pipe as described above. A disadvantage of the current inflatable bladders is that, during the inflation process, pressurized air tends to propagate between the air-impermeable layers and the sock by entering the ends of the inflatable bladder at the end caps. The propagating air tends to bubble, which in extreme cases can delaminate the air-impermeable layer from the sock. Such air bubbles can also be large enough to impede deflation of the bladder sufficient to hamper easy removal from the sewer, which increases the likelihood of damage during removal. In extreme cases, a bubble can prevent the removal of the bladder altogether.

It is desirable to have an inflatable bladder in which air does not propagate between the sock and air-impermeable layer to avoid the potential delamination of the air-impermeable layers from the sock and permit the complete deflation of the bladder.

SUMMARY OF THE INVENTION The invention addresses the problems and disadvantages of previous bladders and relates to an inflatable bladder (10) comprising an elongated, tubular body portion (12), defining a hollow interior and having open ends, which are closed by first and second end portions (18, 20). At least one of the tubular body portion, first end portion, and second end portion is made from a laminate comprising air-impermeable outer and inner layers (30, 32) and an electrically conductive intermediate layer (34) positioned between the outer and inner layers. A vent (50) extends from the intermediate layer through one of the inner and outer layers to vent air from the intermediate layer beyond the one of the inner and outer layers.

Preferably, the vent extends from the intermediate layer to the outer layer. The vent is a passageway formed in the one of the inner and outer layers. The passageway is dimensioned such that a portion of the passageway closes when the inflatable bladder is deflated.

Either or both of the outer and inner layers can comprise multiple layers. The outer layer is preferable made from fluorosilicone or fluorocarbon. The conductive layer can be made from carbon fiber, preferably a carbon fiber mesh. Preferably, a strengthening web (72) is disposed between the intermediate layer and the one of the outer

The invention also relates to a method for making an inflatable bladder (10) for use in repairing a failure in a pipe. The method comprises: positioning a conductive material (64) on a form (54) in the shape of the bladder to form the conductive layer; positioning an insert (66) on the form such that a portion of the insert is adjacent the conductive layer; positioning an air- impermeable material (52 or 70) about the form to form the air-impermeable layer and such that a portion of the insert extends beyond the air-impermeable material; and removing the insert to create a passage (50) extending from the conductive layer to the exterior of the air- impermeable material.

Preferably, the positioning of the insert occurs prior to the positioning of the air-impermeable layer. The positioning of the air-impermeable material can include the wrapping of a strip of air-impermeable material (52 or 70) about the form. The method can further include the positioning of a strengthening web (72) between the insert and the air-permeable layer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 illustrates a side view of an inflatable bladder with a breather vent according to the invention; FIG. 2 is a left end view of the inflatable bladder of FIG. 1 illustrating the exterior opening of the breather vent;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2 and illustrating the breather vent and an electrical coupler;

FIG. 4 is an enlarged view of the left end of the bladder of FIG. 4 more clearly illustrating the breather vent and electrical coupler;

FIG. 5 is a schematic view of the building of a first air-impermeable layer of the inflatable bladder on a mandrel or tool; FIG. 6 is a schematic view illustrating the buildup of a conductive layer over the first air-impermeable layer of FIG. 5;

FIG. 7 is a schematic view illustrating the positioning of an insert on the conductive layer after the buildup of the conductive layer of FIG. 6; and FIG. 8 is a schematic view illustrating the buildup of a second air- impermeable layer about the conductive layer and the insert in combination with the placing of a structural support between the insert and the second air-impermeable layer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates an inflatable bladder 10 comprising a generally constant diameter middle portion 12 and opposing concentrically tapered end portions 14, 16. Each of the end portions terminates in an opening 18, 20 (FIG. 4) sized to receive a conduit 22, 24, respectively. Couplers 26, 28 close off the openings 18, 20 and connect the corresponding conduit 20, 22 to the appropriate end 14, 16.

Referring to FIGS. 3 and 4, the inflatable bladder 10 is made from a laminate comprising inner and outer air-impermeable layers 30, 32 between which is positioned an electrically conductive layer 34. Preferably, the inner and outer air-impermeable layers are made from rubber, such as fluorosilicone or fluorocarbon rubber. The conductive layer 34 preferably is made from carbon fiber, specifically, a sock or cylinder of a carbon fiber mesh.

As best seen in FIG. 4, the ends of the carbon fiber sock extend a distance away from the ends of the air-impermeable layers 30, 32. The exposed portions of the carbon fiber sock extending beyond the ends of the air-impermeable layers 30, 32 are electrically coupled to an electrical conduit by the couplers 26, 28. Each of the couplers 26, 28 includes an inner cone 36 and an outer cone 38. The inner cone 36 has an axial opening 40, a clamping surface 42, and an annular angled shoulder 44. The outer cone comprises a clamping surface 48 sized to receive the inner cone clamping surface and the bladder therebetween. The conduit 22 couples to the outer cone 38 and supplies pressurized air to the bladder 10 and electrically couples to the inner cone 38 or conductive layer 34 in the traditional manner.

The inner cone 36 is received within the opening 18 and the exposed portions of the carbon fiber sock are wrapped around the base. The outer cone 38 is positioned over the inner cone 36 so that the clamping surfaces 42, 48 compressively trap a portion of the bladder therebetween.

A breather vent 50 extends from the conductive layer 34 through the outer air- impermeable layer 32. The breather vent 50 is preferably an opening or passageway in the outer air-impermeable layer 32 that fluidly connects the conductive layer 34 to the exterior of the inflatable bladder 10. The passage has opposing ports, one of which faces the exterior of the bladder, and the other faces the conductive layer. The breather vent 50 is exaggerated for clarity in the drawings. Preferably, the size of the passageway is such that the passageway will collapse and be self-closing when air is withdrawn from the inflatable bladder 10 during bladder deflation. It is within the scope of the invention for the breather vent 50 to have a more complex structure than merely a passageway extending from the conductive layer 34 through the outer air-impermeable layer 32. For example, the passageway could contain a one-way valve or check valve. The check valve would ensure the exhausting or releasing of air propagating between the inner and outer air- impermeable layers 30, 32 along the conductive layer 34 and the closure of the breather vent 50 during deflation. It should also be noted that the breather vent 50 could just as easily extend from the conductive layer 34 through the inner air- impermeable layer 30 and into the interior of the inflatable bladder 10. For ease of manufacture, it is preferred that the breather vent extend from the conductive layer 34 through the outer impermeable layer 32. It is also preferred that there be a breather vent 50 on each end 14, 16 of the inflatable bladder 10. It is further within the scope of invention to have more than one breather vent 50 on each end 14, 16.

The manufacture of the inflatable bladder 10 with a breather vent 50 according to the invention is illustrated in FIGS. 5-8. FIG. 5 illustrates the buildup of the inner air-impermeable layer 30, which is preferably created by wrapping a strip 52 of air- impermeable material about a mandrel or tool 54. The tool 54 has an exterior shape corresponding to the desired finished exterior shape of the inflatable bladder 10. For example, the tool 54 has a substantially constant diameter middle portion 56 with concentrically tapered ends 58, 60, from which extend projections 62, 64, which form the end of openings 18, 20 in the inflatable bladder.

The buildup of the strip of air-impermeable material 52 about the tool 54 starts, for example, by beginning the wrapping of the strip 52 at one end portion 58, and ending at another end portion 60. Depending on the desired thickness of the inner air-impermeable layer 30, multiple strips of air-impermeable material 52 may be wrapped about the tool 54, preferably one strip on top the other. The strips of air- impermeable material 52 are preferably wrapped in a helical-type fashion.

Referring to FIG. 6, once the inner air-impermeable layer 30 is built up on the tool 54, the conductive layer 34 is then built on the tool on top of the inner air- impermeable layer 30. The conductive layer 34 is preferably built up on the tool by taking a cylinder or sock 64 of conductive material and sliding it over the strips of air- impermeable material 52 built up on the tool. Preferably, the sock 64 is of such a length that the ends of the sock extend slightly beyond the ends of the air- impermeable material 52. The sock 64 can be made from a conductive material that is capable of radial stretching or expansion to provide a snug fit relative to the inner air- impermeable layer 30 as the sock 64 is slid over the tool 54.

Referring to FIG. 7, after the conductive layer 34 is built up on the tool 52, an insert 64 has one portion attached to the sock 64 wherever it is desired to form the breather vent 50. For purposes of this description, only one insert 66 is illustrated. Preferably, an insert 66 is attached to each end of the sock 64. The insert 66 is preferably a ribbon made from Teflon™ and/or coated with Teflon™.

Referring to FIG. 8, after the insert 66 is attached, the outer air-impermeable layer 32 is built up on the tool 54. As with the inner air-impermeable layer 30, the outer air-impermeable layer 32 is built up by wrapping a strip of air-impermeable material 70 about the tool 54 on the exterior of the sock 64. The strip of air- impermeable material 70 is wrapped in the same manner as the strip 52, preferably in a helical fashion.

During the wrapping of the strip of air-impermeable material 70, the position of the insert 66 is controlled so that the free end of the insert 66 does not become trapped under the strip of air-impermeable material 70, ensuring that the free end of the insert 66 is accessible to the exterior of the bladder after the buildup of the outer air-impermeable layer 32.

A support web 72 is positioned on top of the insert 66 at a location at least corresponding to the area where the strip of air-impermeable material 70 overlies the insert 66. The support web 72 is preferably placed over the insert 66 prior to the strip of air-impermeable material 70 being wrapped over the insert 66. The support web 72 provides additional strength to the adjacent portion of the air-impermeable strip 70 and aids in preventing the insert 66 from tearing or cutting the air-impermeable layer 32 when the insert 66 is removed. The outer air-impermeable layer 32, as with the inner air-impermeable layer

30, can be built up of one or more strips of air-impermeable material 70. If multiple strips of air-impermeable material 70 are wrapped around the tool 54, it is preferred that the edges of the strip 70 do not overlap. It is also preferred that the support web 72 be positioned at least at the outer layer of the multiple layers of air-impermeable strips 70.

Upon the completion of the buildup of the outer air-impermeable layer 32, the inner and outer air-impermeable layers 30, 32 and the conductive layer 34 are subjected to a curing process, typically heat, for the fluorocarbon and fluorosilicone rubber. Once the bladder is cured, the insert 66 is removed, preferably by pulling on the free end of the insert 66 extending from the outer air-impermeable layer 32. The removal of the insert 66 leaves a passage extending through the outer air-impermeable layer 32 to the conductive layer 34 that is generally in a shape corresponding to the insert 66. The passage forms the breather vent 50.

In some implementations of the invention, a relatively large amount of force must be applied to the insert 66 to remove it from the cured outer air-impermeable layer 32. The support web provides additional structural support to the outer air- impermeable layer 32 along the insert 66 and prevents the tearing of the outer air- impermeable layer 32 in response to the force the insert 66 applies to the outer air- impermeable layer when the insert 66 is pulled. It should be noted that although the insert 66 is shown as extending from the conductive layer 34 through the outer air-impermeable layer 32, the insert 66 could just as easily extend from the conductive layer 34 through the inner air-impermeable layer 30. However, such an inwardly directed orientation of the insert 66 would require some modifications to the process. For example, the free end of the insert 66 would extend along the projections 60 of the tool and be wound through the various layers of the inner air-impermeable layer 30 to ensure that the free end of the insert 66 could be grasped and pulled after the curing of the buildup bladder. Also, support web 72 would need to be disposed between the appropriate portions of the air- impermeable strips 50. The cured bladder 10 is removed from the tool by blowing air into one or more of the openings 18, 20 of the ends 14, 16 of the bladder 10. The pressurized air helps to lift the bladder 10 off the tool and enable the bladder to be slid off of the tool. A lubricant can also be used alone or in combination with the pressurized air to enhance the sliding of the bladder off the tool. The inner and outer air-impermeable layers 30, 32 and the conductive layer 34 typically can stretch a sufficient amount to permit the sliding removal of the bladder from the tool 52. The bladder is preferably removed from the tool after the insert 66 is removed. However, the bladder can be removed earlier if desired.

Claims

1. An inflatable bladder (10) for use in repairing a failure in a pipe, the inflatable bladder comprising: an elongated, tubular body portion (12) defining a hollow interior and having open ends, first and second end portions (18, 20), each closing one of the tubular body open ends, at least one of the tubular body portion, first end portion, and second end portion being made from a laminate comprising air-impermeable outer and inner layers (30, 32) and an electrically conductive intermediate layer (34) positioned between the outer and inner layers; and a vent (50) extending from the intermediate layer through one of the inner and outer layers to vent air from the intermediate layer beyond the one of the inner and outer layers.

2. An inflatable bladder according to claim 1 wherein the vent extends from the intermediate layer to the outer layer.

3. An inflatable bladder according to claims 1 and 2 wherein the vent is a passageway formed in the one of the inner and outer layers, said passageway having a first port in fluid communication with the intermediate layer and a second port in fluid communication with one of the hollow interior and atmosphere.

4. An inflatable bladder according to claim 3 wherein the passageway is dimensioned such that at least one of the ports closes when the inflatable bladder is deflated.

5. An inflatable bladder according to claims 1-4 wherein the one of the outer and inner layers comprises multiple layers.

6. An inflatable bladder according to claims 1-5, and further comprising a strengthening web (72) disposed between the intermediate layer and the one of the outer and inner layers and located near the passageway.

7. An inflatable bladder according to claim 6 wherein the strengthening web is positioned between the two layers of the multiple layers farthest from the intermediate layer.

8. An inflatable bladder according to claims 1-7 wherein the outer layer is made from flourosilicone.

9. An inflatable bladder according to claims 1-7 wherein the outer layer is made from flourocarbon.

10. An inflatable bladder according to claims 1-9 wherein the intermediate layer is made from carbon fiber.

11. An inflatable bladder according to claim 10 wherein the carbon fiber is woven.

12. A method for making an inflatable bladder (10) for use in repairing a failure in a pipe, the inflatable bladder comprising an elongated, tubular body (12) made from a laminate having an air-impermeable layer (30 or 32) and an electrically conductive layer (34) abutting the air-impermeable layer, and a vent (50) extending from the electrically conductive layer through the air-impermeable layer to vent air from the electrically conductive layer beyond the air-impermeable layer, the method comprising: positioning a conductive material (64) on a form (54) in the shape of the bladder to form the conductive layer; positioning an insert 66) on the form such that a portion of the insert is adjacent the conductive layer; positioning an air-impermeable material (52 or 70) about the form to form the air-impermeable layer and such that a portion of the insert extends beyond the air- impermeable material; and removing the insert to create a passage (50) extending from the conductive layer to the exterior of the air-impermeable material.

13. The method of claim 12 wherein the positioning of the insert occurs prior to the positioning of the air-impermeable layer.

14. The method of claims 12-13 wherein the positioning of the conductive material comprises sliding the conductive layer over the form.

15. The method of claims 12-14 wherein the sliding of the conductive material comprises sliding a tube (64) of conductive material over the form.

16. The method of claims 12-15 wherein the positioning of the air- impermeable material comprises wrapping a strip of air-impermeable material (52 or 70) about the form.

17. The method of claim 16 wherein the wrapping of the air-impermeable strip includes wrapping the air-impermeable strip into multiple layers such that the insert extends between at least one pair of adjacent layers of the multiple layers of the air-impermeable strip.

18. The method of claims 12-17 and further comprising the step of positioning a strengthening web (72) between the insert and the air-permeable layer.

19. The method of claim 18 wherein the positioning of the strengthening web comprises positioning the strengthening web between the insert and the pair of adjacent air-permeable layers such that upon the removal of the insert, the insert bears against the strengthening web.

20. The method of claims 12-19 wherein the positioning of the air- impermeable layer occurs after the positioning of the conductive layer.

21. The method of claims 12-20 and further comprising the step of placing a second layer (32 or 30) of air permeable material about the form such that the second layer of air-impermeable material is on an opposite side of the conductive layer.

22. The method of claims 12-21 and further comprising the step of curing the air permeable layer.

23. The method of claim 22 wherein the step of removing the insert occurs after the curing of the air permeable layer.

24. The method of claims 12-23 wherein the insert is a ribbon and the step of removing the insert comprises pulling the insert.