Pipes and tubular conduits – Repairing – Patches
Reexamination Certificate
2002-05-24
2004-05-11
Hook, James (Department: 3752)
Pipes and tubular conduits
Repairing
Patches
C138S125000, C405S150100
Reexamination Certificate
active
06732763
ABSTRACT:
FIELD OF THE INVENTION
The present invention provides a tubular lining material for lining pipes. The liner is made from a support sleeve of stretch-resistant woven fabric disposed between two sealing sleeves of resin-impregnated non-woven material. The invention also provides pipes lined with the stretch-resistant liners as well as methods for lining pipes with stretch-resistant liners.
BACKGROUND OF THE INVENTION
Over time, pipelines, such as those used in sewer systems, water systems, and rainwater conductors, may undergo structural deterioration and develop cracks or leaks due to internal friction, large temperature swings, and the shifting of the earth. Unfortunately, because these pipes are typically buried, accessing the pipes to fix these cracks and leaks is no easy matter. This is particularly true for lateral pipes. Laterals are underground pipelines that connect a main pipeline to end users in buildings such as homes or office buildings. Laterals often connect with the main line at angles of up to 90° and are usually only accessible from one end. In addition, laterals have narrow diameters, typically only 4 to 6 inches, making cracks and leaks difficult to access from the inside.
To avoid the expense and effort of digging up sewer pipes and replacing flawed parts, a variety of methods for lining the interior of pipes have been developed. A common technique makes use of a curable resin-impregnated felt sleeve which may be inserted into a cracked pipe and expanded in a radial direction until it presses against the interior surface of the pipe. Once a sleeve has been fitted into the pipe in this manner, the resin contained within the felt is cured, bonding the felt to the pipe and producing a hardened internal liner.
Selecting the length of the liner for these applications is critical because the liner must cover the last joint before the lateral joins the main pipe. If the liner is too short and does not cover the joint, an additional process must be used to seal the joint which adds costs and usually does not provide a good final product. Conventional solutions include grouting the joint or inserting an additional partial liner over the joint. On the other hand, if the liner is too long and extends through the lateral into the main, it can create a blockage. Typically, the part of the liner that extends into the main must be removed with a robotic cutting device. For these reasons, controlling the location of the end of the liner is of considerable importance. Unfortunately, the radially expandable liners presently in use expand not only in the radial direction during application but in the axial direction as well, making it difficult to gauge the appropriate length of the liner prior to installation.
In the past, manufacturers of pipe liners have attempted to overcome these shortcoming by incorporating layers of fiberglass or carbon fiber into the liners because these materials are strong and do not stretch easily. Unfortunately, fiberglass and carbon fiber are relatively stiff, making these liners unsuitable for use in applications where the liner is installed by inverting it into the interior of the pipe.
Thus, a need exists for a pipe liner that is stretch-resistant in the longitudinal direction and that is easy and inexpensive to install.
SUMMARY OF THE INVENTION
The present invention provides stretch-resistant liners for pipes, pipes lined with stretch-resistant liners, and methods for lining pipes with stretch-resistant liners. The liners of this invention are particularly useful for lining lateral pipes and other pipes that cannot be easily accessed from both ends.
One aspect of the present invention provides a stretch-resistant liner for a pipe which is made of a multi-layered tube-shaped lining that includes a first sealing sleeve comprising a layer of non-woven material impregnated with a curable resin, the first sealing sleeve having an inner surface and an outer surface; a support sleeve comprising a layer of stretch-resistant woven material, the support sleeve having an inner surface and an outer surface; a second sealing sleeve comprising a layer of non-woven material impregnated with a curable resin, the second sealing sleeve having an inner surface and an outer surface; and optionally, a barrier layer comprising a film of air impermeable plastic which is coated onto the outer surface of the second sealing sleeve. Within this liner, the inner surface of the support sleeve is disposed against the outer surface of the first sealing sleeve and the outer surface of the support sleeve is disposed against the inner surface of the second support sleeve to form a tube-shaped liner having concentric sleeves. In one embodiment of this invention, the stretch-resistant woven material is a stretch-resistant scrim.
Another aspect of the invention provides pipes that are lined with stretch-resistant liners of the type described above.
Still another aspect of the invention provides a method for lining the interior of a pipe with a stretch-resistant liner, including the steps of cutting a stretch-resistant, tube-shaped, resin-impregnated liner having an external surface and an internal surface, to a predetermined length and radius, disposing the exterior surface of the liner against the inner surface of the pipe, and curing the resin in the liner to form a hardened lining against the interior surface of the pipe. The stretch-resistant liner described above is particularly suited for use with this method.
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Choi Jin
Williamson John S.
Foley & Lardner
Hook James
Lantor, Inc.
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