Stock material or miscellaneous articles – Pile or nap type surface or component – Particular shape or structure of pile
Utility Patent
1998-08-10
2001-01-02
Cole, Elizabeth M. (Department: 1771)
Stock material or miscellaneous articles
Pile or nap type surface or component
Particular shape or structure of pile
C428S298100, C428S299100, C428S299700, C405S150100, C405S151000
Utility Patent
active
06168846
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a liner strip for lining underground pipes such as pipelines, tunnels and structures. More particularly, the present invention relates to a liner strip particularly suitable for, but not limited to, renovating and/or protecting sewer pipes.
2. Description of the Prior Art
Sewer pipes often become obstructed or structurally deteriorated due to pipe corrosion by hydrogen sulfide, general degradation, organic growth, and root infiltration. As a result, the flow of sewage can become obstructed or the sewer pipe may collapse. A degraded sewer pipe, even if not obstructed, may allow ground water to infiltrate, thus unnecessarily increasing fluid flow to a treatment plant.
The cost associated with replacing sewer pipes can be prohibitively high, and disruption to above ground traffic may not be feasible. Therefore, sewer pipes are often relined rather than replaced. In order to minimize above ground disruption during sewer pipe relining, sewer pipes are often relined using technology that does not require digging a trench above the sewer pipe.
European Patent number 0450220, assigned to Danby Pty Ltd., discloses a method of renovating or protecting sewers or pipes which is effected using a liner strip and joiner strip spirally wound and locked together. This method, known as “PANEL LOK 3” was an improvement over the earlier “PANEL LOK 2” method of International Publication Number WO 88/05884, also assigned to Danby Pty Ltd. European patent publication 0475769 discloses a method of renovating and/or protecting oval or egg-shaped sewers and pipes known as “OVILOK.”
While these methods have generally proven successful, it would be desirable to increase the liner stiffness and tensile strength to resist forces imposed on the liner during installation, e.g., group pressure and hydrostatic pressure, and forces imposed on the liner during its service life (e.g., earth pressure and hydrostatic pressure). This could be accomplished by either increasing the liner thickness or increasing the height of the flanges or T-shaped formations on the liner. However, merely increasing the thickness of the liner would not be acceptable since this would make the liner too costly to achieve significant increases in stiffness.
In addition, increasing the height of the flanges or T-shaped formations on the liner strip would not be acceptable as this would reduce the effective diameter of the lined pipe and/or sewer.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a liner strip which has increased stiffness and tensile strength.
It is a further object to provide a liner strip which does not require a significant increase in the liner thickness or cost in order to achieve such increased stiffness and tensile strength.
Other preferred objects of the present invention will become apparent from the following description.
According to one broad aspect of the invention, there is provided a liner strip for lining an interior surface of a pipe of the type having a body and optional special flanges and/or T-shaped formations, the liner being formed of polyvinylchloride (PVC) or other plastics material, wherein reinforcing fibers or strands are extruded into and/or onto the body, flanges and/or T-formations.
In a preferred embodiment, the fibers or strands are aramid or KEVLAR® fibers (manufactured and sold by DuPont). Alternatively, the fibers or strands may be made of metal, e.g., stainless steel. The fibers or strands may be extruded into the liner strip and/or on the surfaces thereof.
It is believed that the fibers or strands will allow the liner strip to be formed (curved) to the desired installation shape with little extra applied force required.
Other objects and features of the present invention will be apparent from the following detailed description of the preferred embodiment.
REFERENCES:
patent: 4179539 (1979-12-01), Schweizer
patent: 5101863 (1992-04-01), Fuji et al.
patent: 5145281 (1992-09-01), Molyneux
patent: 5725328 (1998-03-01), Schmager
Cole Elizabeth M.
Danby of North America
Reed Smith Hazel & Thomas LLP
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