WO2001077569A2

WO2001077569A2 - Fluorocarbon repair bladder

Info

Publication number: WO2001077569A2
Application number: PCT/US2001/011482
Authority: WO
Inventors: Nancy J. Marks
Original assignee: Flexfab Horizons International, Inc.
Priority date: 2000-04-05
Filing date: 2001-04-05
Publication date: 2001-10-18
Also published as: AU2001251460A1; WO2001077569A3

Abstract

An inflatable bladder for repairing a failure in an underground pipe with a thermally reactive material is made of fluorocarbon rubber. At least one end section (14, 16) of the bladder has an eccentric taper so that one side is substantially collinear with a middle section (12) of the bladder. A conduit for exhausting steam from the bladder is positioned near the collinear side of the end section.

Description

FLUOROCARBON REPAIR BLADDER RELATED APPLICATION

This application claims priority on United States Provisional Application Number 60/194,754. BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an inflatable bladder for positioning and applying a patch to a broken underground pipe, and, more specifically, to an inflatable bladder that is substantially inert relative to the patch material. 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 sandwich of opposing outer layers of fluorosilicone between which is positioned a carbon fiber mesh, commonly referred to as a carbon fiber sock. Electrical conductors, usually entrained about, forming part of, or contained within the conduit, 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 fluorosilicone inner and, outer layers, resulting in a transfer of the heat to the patch. 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. One disadvantage of the conventional inflatable bladder arises from the fluorosilicone outer layer being reactive with the activated styrene patch, especially when the bladder and patch are heated. There is a tendency for the activated styrene patch to simultaneously adhere to the interior of the underground pipe and the fluorosilicone outer layer of the inflatable bladder, reducing the efficacy of the patch. The sandwich construction of the conventional inflatable bladders is also relatively difficult and time-consuming to assemble. The internal fluorosilicone layer must first be formed about a tool, typically by wrapping one or more layers of fluorosilicone about the tool. The electricity conducting fiber sock is wrapped around the inner fluorosilicone layer. The outer fluorosilicone layer is then built up on the carbon fiber sock. Yet another disadvantage of the conventional repair bladder is that the outer fluorosilicone layer is susceptible to damage through abrasion, especially as the sock is dragged through the underground pipe, which can contain many discontinuities or objects capable of damaging the fluorosilicone layer. Finally, the carbon fiber sock has a tendency to trap air within and prevent the complete deflation of the bladder, increasing the likelihood that the bladder might get caught in the pipe during removal.

It is desirable to have an inflatable bladder that is less complex to manufacture, more abrasion-resistant, and relatively inert with respect to the patch material than prior art inflatable bladders.

SUMMARY OF THE INVENTION The invention addresses the disadvantages and shortcomings of prior inflatable bladders. The invention relates to an inflatable bladder made entirely of fluorocarbon. Steam heat is the preferred heat source. The bladder preferably has an elongated body with eccentric end sections, which in combination minimize the pooling of liquid in the bottom. Each eccentrically tapered end terminates in a fitting having a coupling adapted to connect to a steam tube. Preferably, one of the couplings functions as a steam inlet and the other coupling functions as a steam outlet. At least the steam outlet is substantially coplanar with the bottom of the inflatable bladder to aid in removing any moisture in the bladder without pooling. BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a side elevational view of the bladder according to the invention; FIG. 2 is a sectional view taken along line 2-2 of FIG. 1; FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG.4 is a schematic view illustrating the insertion and positioning of a bladder of FIG. 1 in an underground pipe;

FIG. 5 is similar to FIG. 4 with the bladder inflated; and FIG. 6 is a sectional view taken along lines 6-6 of FIG. 5. DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates an inflatable bladder 10 according to the invention. The inflatable bladder 10 can be conceptually divided into three areas: an elongated, substantially constant diameter section 12, a first tapered end section 14, and a second tapered end section 16. Each of the end sections 14, 16 terminates in a fitting 18, 20, respectively. Each of the fittings 18, 20 includes a coupling 19, 21, respectively, adapted to receive and mount a steam supply line.

Referring to FIGS. 2 and 3 specifically and FIG. 1 generally, the middle section 12 has a generally circular cross section. The cross section is substantially constant throughout the entire length of the middle section 12. The end section 16 eccentrically tapers from the middle section 12 toward the fitting 20, while maintaining a generally circular cross section. A result of the eccentric taper in combination with the generally circular cross section is the one side of the end section 16 (here shown as the bottom surface) remains substantially colinear with one side of the middle section (here shown as the bottom surface). The end section 14, like the end section 16, is also eccentrically tapered with a continuously smaller circular cross section although unlike the end section 16, it need not be eccentrically tapered. The conduit 19 is located above the bottom surface of the end section 14 and the bottom surface of the middle section 12. For the invention to function in the preferred manner, only one of the conduits 19 and 21 needs to be substantially colinear with the bottom of the middle section and/or the end section. Preferably, the conduit 19 is an inlet and the conduit 21 is an outlet or exhaust port. It is more important for the outlet to be colinear with the bottom of the middle section and/or the end section.

The advantage of the end section 16 having a tapered cross section and a bottom in substantially colinear relationship with the bottom of the middle section 12 lies in that any liquid in the bladder will not pool in the middle section 12 of the bladder 10. Instead, liquid will be free to flow or be drawn out of the bladder through the conduit 21 of fitting 20.

Previous inflatable bladders have end sections 14, 16 that are concentrically tapered with a constantly reducing cross section. The concentric taper in combination with a constantly reducing circular cross section created a rise in the bottom of the end section relative to the bottom of the middle section, which would inherently inhibit the flow of fluid from the middle section of the inflatable bladder through the end section, resulting in the pooling of liquid within the middle section. The inflatable bladder 10, including the middle section 12 and end sections

14, 16, is preferably made from fluorocarbon rubber. In the preferred form, the inflatable bladder consists solely of fluorocarbon rubber and is not a laminate or composite. The fluorocarbon inflatable bladder is preferably built up on a tool having an external shape conforming to the internal shape of the inflatable bladder 10. Preferably, the inflatable bladder 10 is built on the tool by wrapping one or more strips of fluorocarbon rubber about the tool and heating the fluorocarbon rubber until it cures.

Referring to FIGS. 4-6, the use of the inflatable bladder 10 is shown in the context of repairing an underground sewer pipe 30 to which access is gained by manholes 32, 34 (or in the absence of manholes, a drilled or dug hole provides access to the pipe 30). A failure 36 exists in the sewer pipe 30 between the manholes 32, 34.

The inflatable bladder 10 is positioned within the sewer pipe 30 by inserting it through the manhole 32. Steam lines 38, 40 each have one end affixed to one of the fittings 18, 20, and another end connected to a steam generator 42. The steam lines or, alternatively, a cable on a winch, 38, 40 can be used to push and pull the inflatable bladder 10 within the sewer 30 until the inflatable bladder 10 is positioned as desired with respect to the failure 36.

A patch material 44 circumscribes the inflatable bladder and is adhered thereto in one of many well-known ways, such as by friction or adhesive. In aligning the bladder with the failure 36 in the sewer pipe 30, it is preferred that the inflatable bladder 10 be positioned such that the patch 44 is axially aligned with the failure 36.

Referring to FIG. 5, once the patch 44 is axially aligned with the failure 36, steam is introduced into the end section 14 of the inflatable bladder 10 through the steam line 38. The introduction of the steam into the inflatable bladder 10 inflates and heats the inflatable bladder 10. As the bladder 10 is inflated, the patch 44 is brought into contact with a portion of the sewer pipe 30 in which the failure 36 is located, the continued introduction of steam from the steam generator 42 into the inflatable bladder 10 through the steam line 38 maintains the inflatable bladder in an inflated state and continues to heat the bladder, which, in turn, heats the patch 44. The introduction of steam continues until the patch 44 is heated to a temperature where it reacts with and cures to the sewer pipe 30. Preferably, the patch 44 is made from activated styrene, which begins to cure at approximately 200 F. Once initiation begins, the exothermic nature of the reaction pushes the temperature to approximately 300 F. The cure is complete in approximately 1 hour. Once the patch 44 is cured to the sewer pipe, the introduction of steam into the inflatable bladder 10 can cease. The steam is then withdrawn from the inflatable bladder 10 through the steam holes 40 by the steam generator 42. The withdrawal of the steam from the inflatable bladder 10 collapses the bladder and permits its removal.

A natural consequence of circulating steam through the inflatable bladder 10 and subsequently removing the steam at the end of the patching process is that some moisture from the steam can condense on the interior of the inflatable bladder 10. To completely collapse the inflatable bladder 10 and ensure its removal, it is important to prevent the moisture from pooling within the inflatable bladder 10. The eccentrically tapered ends of the inflatable bladder 10 substantially prevent the water from pooling within the inflatable bladder since the bottom of the inflatable bladder is generally planar and the outlet fitting 20 and conduit 21 are aligned with the generally planar bottom, eliminating low areas or depressions relative to the outlet fitting 20.

The steam generator will draw substantially all of the moisture from the inflatable bladder 10, permitting a substantially complete collapse of the of the bladder, easing the removal of the bladder from the sewer pipe. Alternatively, in a one pass method, the steam will condense and allow for essentially a complete collapse of the bladder. Residual condensate would leak from a thermally activated trap at the outlet, in this case.

The bladder 10 according to the invention addresses many of the disadvantages of the prior art bladders. The fluorocarbon bladder 10 is more resistant to abrasion than the previous flurosilicone bladders. Additionally, the fluorocarbon is relatively inert with respect to the preferred patch material, resulting in a better and more consistent repair. The lack of a carbon fiber sock eliminates the tendency for the sock to trap air that can prevent the withdrawal of the bladder from the pipe. Further, the eccentric ends of the bladder aid in preventing the pooling of moisture within the bladder that could otherwise interfere with the deflation of the bladder and its subsequent removal.

It is worth noting that since the steam is preferably recirculated between the steam generator 42 and the inflatable bladder 10 by the steam lines 38 and 40, it is only necessary for the downstream end section, the end section 10 in the case of the invention, to be eccentrically tapered relative to the middle section 12 of the inflatable bladder 10 to ensure the removal of moisture from within the inflatable bladder to prevent the pooling of the moisture. This is also true if the one-pass thermal trap method is used and condensate allowed to bleed out into the sewer. Similarly, it is also within the scope of the invention for only one of the inlet or outlet fittings 18, 20 to be substantially at the same level as the bottom of the inflatable bladder 10 to ensure the removal of the moisture. However, it is within the scope of the invention for both end sections 14, 16 to be eccentrically tapered and have their respective fittings 18, 20 positioned so that the outlet is substantially coplanar with the bottom of the inflatable bladder to thereby enable steam to be introduced and withdrawn from the inflatable bladder 10 in either direction.

While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.

Claims

CLAIMSI claim:

1. An inflatable bladder for use in repairing underground pipes with a thermally reactive patch material, the bladder comprising an elongated, substantially constant diameter middle section (12); a first end section (14) extending from one end of the middle section and second end section (16) extending from the other end of the middle section, each end section having a fitting (18, 20), characterized by: the middle section being formed of an inert material incapable of reacting with the thermally reactive patch material.

2. An inflatable bladder according to claim 1 wherein the first and second end sections are also formed of the same inert material.

3. An inflatable bladder according to claims 1 or 2 wherein the thermally reactive patch material comprises activated styrene and the inert material is fluorocarbon rubber.

4. An inflatable bladder for use in repairing underground pipes with a thermally reactive patch material, the bladder comprising an elongated, substantially constant diameter middle section (12); a first end section (14) extending from one end of the middle section and a second end section (16) extending from the other end of the middle section, a fitting (18) on the first end section (14) having an input conduit (19) connectable to a source of heated fluid and another fitting (20) on the second end section (16) having an exhaust conduit (21) connectable to a sink for the heated fluid, characterized by: the second end section being eccentrically tapered so that one side of the second end section is substantially collinear with one side of the middle section.

5. An inflatable bladder according to claim 4 characterized by the first end section being tapered.

6. An inflatable bladder according to claim 5 wherein the first end section is eccentrically tapered so that one side of the second end section is substantially collinear with one side of the middle section.

7. An inflatable bladder according to claims 4 - 6 wherein the exhaust conduit is near the one side of the second end section substantially collinear with one side of the middle section.

8. An inflatable bladder according to claims 4 - 7 wherein the source of heated fluid is a steam generator and the heated fluid is steam.

9. An inflatable bladder according to claims 4 - 8 wherein the middle section is formed of an inert material incapable of reacting with the thermally reactive patch material.

10. An inflatable bladder according to claim 9 wherein the thermally reactive patch material comprises activated styrene and the inert material is fluorocarbon rubber.