Process for installing a pipe liner

• US 5,861,116 A
• Filed: 09/17/1996
• Issued: 01/19/1999
• Est. Priority Date: 08/31/1994
• Status: Expired due to Fees

• Current Assignee: Plastic Inventions and Patents Incorporated
• Original Assignee: Plastic Inventions and Patents Incorporated
• Inventors: Mandich, Ivan C.
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US08/714,818
• Time in Patent Office: 854 Days
• Field of Search: 264/516, 264/269, 264/36, 264/35, 264/230, 156/237, 156/294, 138/97
• US Class Current: 264/35
• CPC Class Codes: B29C 53/08 of tubes or other profiled members
• CPC Class Codes: B29C 63/343 the tubular sheathing having a deformed non-circular cross-section prior to introduction
• CPC Class Codes: F16L 55/1654 and being inflated

Abstract

A thermoplastic liner is extruded in cylindrical form and deformed at a temperature below the crystallization temperature of the polyethylene material forming the liner into a generally W-shaped configuration. The liner in that configuration has three convex lobes and two concave lobes along one side of the liner with a convex portion of the liner wall along the opposite side. The cylindrical liner is initially extruded in cylindrical form and deformed by a series of axially spaced sets of rollers progressively inclined toward a vertical position wherein the final W-shaped configuration of the liner is formed. The liner has a cross-section in any direction less than one-half of the diameter of the liner when expanded into a cylindrical configuration. The deformed liner is coiled about a reel. At an installation site, the liner is pulled from the reel through the pipe and sealed at opposite ends. Steam under pressure expands the W-shaped liner to a cylindrical configuration to line the pipe.

Claims

1. A process for installing in situ a thermoplastic liner in a generally horizontally extending, generally cylindrical pipe, comprising the steps of:

providing an elongated hollow liner formed of a shape memory thermoplastic material having a longitudinal axis and a non-cylindrical cross-section, said liner being expandable, by injecting a heated fluid under pressure therethrough, into a generally cylindrical cross-section from said non-cylindrical cross-section and to a certain outside diameter corresponding approximately to the inside diameter of said pipe, said liner being defined in cross-section by a continuous liner wall having three convex lobes of substantially the same lateral extent and two concave lobes along one side of said liner facing in a generally radial direction and, in said non-cylindrical cross-section, having a lateral extent in any cross-sectional direction less than one-half said certain outside diameter of said liner, said liner having longitudinal axis generally parallel to said longitudinal axis of said liner, said two concave lobes straddling a convex lobe intermediate a remaining pair of said three convex lobes, said liner wall including a convex portion opposite said concave lobes and having a curvature less than the curvature of said lobes, said non-cylindrical cross-section distributing the stresses applied to said lobes of said wall and said concave lobes approaching contact with said convex portion of said liner wall;

inserting said liner into said pipe such that end portions of said liner extend beyond opposite end portions of said pipe;

sealing the end portions of said liner extending beyond the opposite ends of said pipe;

subsequent to the step of sealing the liner and while maintaining the liner sealed, generally conforming said liner to the interior wall of the pipe while maintaining substantially the original predetermined wall thickness by (1) injecting a heated fluid into and through said sealed liner;

(2) pressurizing the interior of said liner to a first predetermined pressure above atmospheric pressure by means of said heated fluid; and

(3) heating the liner to predetermined temperature by heat transfer from said heated fluid to said liner, whereby said non-cylindrical liner returns substantially to its cylindrical cross-section; and

,

increasing the pressure in said liner to a second predetermined pressure above the first predetermined pressure to conform the liner substantially precisely to the interior wall surface contours of the pipe.

2. A process of installing a liner according to claim 1 wherein the liner is formed of a thermoplastic material having a non-cylindrical cross-section altered at a shape-memory activation temperature from a generally cylindrical cross-section having an original diameter substantially comparable to the inside diameter of the pipe to be lined and wherein the step of reheating the liner includes heating the liner to a predetermined temperature by heat transfer from the heated fluid to the liner to substantially erase its memory of said non-cylindrical cross-section and return its memory of the cylindrical cross-section.

3. A process for installing in situ a thermoplastic liner in a generally horizontally extending, generally cylindrical pipe, comprising the steps of:

providing an elongated hollow liner formed of a shape memory thermoplastic material having a longitudinal axis and a non-cylindrical cross-section, said liner being expandable, by injecting a heated fluid under pressure therethrough, into a generally cylindrical cross-section from said non-cylindrical cross-section and to a certain outside diameter corresponding approximately to the inside diameter of said pipe, said liner being defined in cross-section by a continuous liner wall having three convex lobes of substantially the same lateral extent and two concave lobes along one side of said liner facing in a generally radial direction and, in said non-cylindrical cross-section, having a lateral extent in any cross-sectional direction less than one-half said certain outside diameter of said liner, said liner having longitudinal axis generally parallel to said longitudinal axis of said liner, said two concave lobes straddling a convex lobe intermediate a remaining pair of said three convex lobes, said liner wall including a convex portion opposite said concave lobes and having a curvature less than the curvature of said lobes, said non-cylindrical cross-section distributing the stresses applied to said lobes of said wall and said concave lobes approaching contact with said convex portion of said liner wall;

inserting said liner into said pipe such that end portions of said liner extend beyond opposite end portions of said pipe;

sealing the end portions of said liner extending beyond the opposite ends of said pipe;

subsequent to the step of sealing the liner and while maintaining the liner sealed, generally conforming said liner to the interior wall of the pipe while maintaining substantially the original predetermined wall thickness by (1) injecting a heated fluid into and through said sealed liner;

(2) pressurizing the interior of said liner to a first predetermined pressure above atmospheric pressure by means of said heated fluid; and

(3) heating the liner to predetermined temperature by heat transfer from said heated fluid to said liner, whereby said non-cylindrical liner returns substantially to its cylindrical cross-section from said non-cylindrical cross-section and to a certain outside diameter corresponding approximately to the inside diameter of said pipe, said liner in said non-cylindrical cross-sectional shape having a lateral extent in any cross-sectional direction less than one-half said certain outside diameter of said liner; and

,

increasing the pressure in said liner to a second predetermined pressure above the first predetermined pressure to conform the liner substantially precisely to the interior wall surface contours of the pipe.