Abstract:
A new liner and method of forming a liner for use in lining the junction between a main pipe and a lateral pipe are provided. A liner tube is joined about one end to a liner member about an aperture in the liner member. A liquid thermoset adhesive is applied around a junction formed between the liner tube and the liner member on a resin impermeable coated side of the liner tube and the liner member. The thermoset adhesive is not affected by temperature changes present during an exothermic reaction when the resin impregnated liner tube and liner member are cured and hardened.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates a method and means for forming a liner for use in lining the junction between a main pipe and a lateral or branch pipe, such as in sewer pipeline repair. 
       BACKGROUND OF THE INVENTION 
       [0002]    One method of repairing the junction between main and lateral sewer pipelines is shown in U.S. Pat. No. 6,039,079. A liner assembly, as shown in  FIG. 3  of the patent, includes a lateral liner  26  connected to a flat sheet liner  28 . Both liners  26 ,  28  are formed of felt or other resin absorbent material. The resin is absorbed into both liners in an uncured state and the liners are held in place in the host pipelines as the resin is cured and hardened to form a hardened liner. 
         [0003]    Lateral liner  26  is formed by connecting side edges of a sheet of liner material with a polymer coating  30  on the exterior side. The edges are sewn together at a seam and a strip of polymer tape  34  is welded over the seam to form an airtight seal. Flat sheet liner  28  has a central aperture therein and is sewn to one end of the lateral liner  26  around the aperture. Then a strip of polymer tape  38  is folded along its length and welded continuously around the juncture to form an airtight seal. 
         [0004]    This method of forming a liner leaves room for improvement. The tape  38  is thermoplastic, which allows it to be applied using heat in a welding operation. The use of a thermal plastic tape, while normally sufficient, can be problematic when the tape is exposed to a heat source such as steam or from an exothermic reaction of the resin as it cures and hardens. This could result in the tape disbanding from the liner. 
         [0005]    There are also structural limitations inherent in tape that can be improved upon in sealing the liner junction. In specific, it is difficult to fold the tape in half and wrap it around the liner junction—one half of the tape on the lateral liner and the other half on the flat sheet liner—without either creating wrinkles in the flat sheet liner or cutting slits in the tape on the flat sheet liner for relief. Either condition risks compromising the airtight seal. 
         [0006]    Still further yet, the tape is applied while the liners are in an unstretched state. It is common to slightly undersize the liner so that when stretched the liner conforms to the interior of the host pipe without wrinkling. However, stretching the liner can compromise the structural integrity of the tape, which was applied to the liner in an un-stretched state. 
         [0007]    Therefore, it is an object of the present invention to provide an improved main/lateral liner and a means and method for forming the liner to provide an airtight seal between the main and lateral portions of the liner. 
       SUMMARY OF THE INVENTION 
       [0008]    One aspect of the invention includes a new method of forming a liner for use in lining the junction between a main pipe and a lateral pipe. The method generally includes taking a liner tube having a first end and an opposite second end and joining the first end of the liner tube to a liner member about an aperture in the liner member. The liner tube has a resin impermeable coated liner tube surface opposite an absorbent material liner tube surface, and the liner member has a resin impermeable coated liner member surface opposite an absorbent material liner member surface. A liquid thermoset adhesive is applied around a junction formed between the resin impermeable coated liner tube surface and the resin impermeable coated liner member surface, and the adhesive is cured. In a preferred form, the liquid thermoset adhesive has sufficiently high viscosity so as not to run along the liner tube or the liner member and is curable with exposure to a curing agent. It is also preferred that the liner member be a flat sheet liner that can be formed in a tubular shape. 
         [0009]    Another aspect of the invention includes forming a liner for use in lining the junction between a main pipe and a lateral pipe wherein a main/lateral liner is stretched radially outwardly around a junction formed between the main or lateral portions of the liner. A liquid thermoset adhesive is applied around the junction between the resin impermeable coated lateral and main portions of the liner while the liner assembly is in a stretched condition. In a preferred form, the main/lateral liner assembly is stretched using an inflation device inserted through an aperture in the main portion of the liner and at least partially into the lateral portion of the liner. It is also preferred that the inflation device extend from a rotatable table upon which the main/lateral liner assembly can be mounted to facilitate both the application and curing of the liquid adhesive. 
         [0010]    Another aspect of the invention includes a new main/lateral liner formed from a liner member and liner tube as previously discussed with a liquid thermoset adhesive disposed about a junction between the liner tube and the liner member. 
         [0011]    Those skilled in the art having the benefit of the disclosure contained herein will appreciate many of the benefits of the various aspects of the present invention. For example, a thermoset adhesive is not affected by temperature changes present during the resin curing process. Applying the adhesive in a liquid state also allows the adhesive to be applied where necessary and avoids the inherent structural limitations of using tape. In addition, one aspect of the invention includes applying the adhesive while the liner is stretched as it would be when expanded against the interior of the host pipe, which helps avoid the risk that the adhesive will loose its structural integrity. These as well as other advantages of the invention will become apparent from the following detailed disclosure of preferred embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of the main/lateral liner assembly of the present invention having an adhesive applied to the junction between the main and lateral portions of the liner. 
           [0013]      FIG. 2  is a sectional view of the apparatus shown in  FIG. 1 , but showing an adhesive bottle applying the adhesive. 
           [0014]      FIG. 3  is a sectional view of a modification in which an inflatable plug and rotating table are utilized in combination with an ultraviolet light which cures the adhesive. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Referring to  FIGS. 1-3 , a main/lateral liner assembly  10  is shown made of a felt or other material that can be impregnated with a curable and hardenable material. The liner assembly  10  includes a lateral liner  12  and a main liner member  14 . The main liner  14  preferably starts as a flat sheet liner and is formed into a cylinder (not shown) prior to installation. The main liner member  14  preferably forms a tubular shape for installation, but a main liner member  14  formed as a rim or collar can also be used. 
         [0016]    The ultimate repair is preferably accomplished by impregnating the liner assembly  10  with a resinous material capable of curing and hardening that contains an exothermic reaction agent therein. The exothermic reaction agent cures and hardens the liner assembly  10  in response to introduction of heat, ultraviolet light or other devices. The result is a hardened liner assembly  10  that has both a main and lateral portion that intersect and are communicated with one another. 
         [0017]    The lateral liner  12  is formed into a cylinder or other shape that fits aperture  16  in the main liner member  14 . The lateral liner  12  is then stitched in a line of stitching  24  to conform to its cylindrical or other shape, and a polymer tape  26  is adhered or welded over the stitches to create an airtight seal. 
         [0018]    The lateral liner  12  is then attached to the main liner member  14  with stitches  18  that extend through the aperture  16  in the main liner member  14 . A resin impermeable coating  20  extends on the exterior of the lateral liner  12  and a resin impermeable coating  22  extends on the upper horizontal surface of the main liner member  14 . It is preferred that the resin impermeable coating is a polymer, but other compositions having similar characteristics may be used as well. The lateral liner  12  is stitched to the main liner member  14  with the coating sides  20 ,  22  both on the exterior. The interior of the tubed lateral liner  12  and the bottom side of the main liner member  14  are comprised of a material which is suitable to soak up and absorb a resinous material capable of curing and hardening. An example of such an absorbent material is felt, or a felt-like material. The resin impermeable coatings  20 ,  22  on one side of the lateral liner  12  and the main liner member  14  create an air tight seal that does not allow the resinous material, or air, to penetrate. However, because the liner assembly  10  is produced from two separate pieces and stitched together, the juncture of the lateral liner  12  and the main liner member  14  may not be air tight. A liquid adhesive  30  is added to supplement the juncture to produce a pliable, air tight seal between the coating side  20  of the lateral liner  12  and the coating side  22  of the main liner member  14 . The adhesive is applied directly to the coatings  20 ,  22  to seal any gap between the two coatings, while not affecting the absorbent material. 
         [0019]    A bottle  28  of liquid adhesive  30  is used to create an adhesive collar  32  at the juncture of the lateral liner  12  and the main liner member  14 . The bottle  28  applies the liquid adhesive  30  in an uncured state that is viscous, but pours onto the coated surfaces that form the juncture between lateral liner  12  and main liner member  14 . The adhesive collar  32  includes a lateral flange portion  34  that engages the outside surface of the lateral liner  12 , and a main flange portion  36  that engages main liner member  14 . Because of the liquid nature of the adhesive  30 , the liquid can be applied where desired, and therefore the problems inherent in using tape wrapped around the juncture between the liner portions are overcome. 
         [0020]    The liquid adhesive  30  may be a silicone, a urethane, an epoxy, a UV curable liquid, or another liquid material capable of adhering to the resin impermeable material and meeting the requirements listed below. The preferred compound for the adhesive is manufactured by DYMAX Corporation of 318 Industrial Lane, Tarrington, Conn., under Product Number 3-20809. In a preferred form, the adhesive collar  32  would meet the following conditions:
       The viscosity is such that the adhesive does not run down the lateral liner  12  or off of the main liner member  14 . The lateral liner  12  is usually posed with its walls in a vertical position or inclined position while the main liner member  14  is usually posed in a horizontal position.   The adhesive has the properties of being adhesive—that is it adheres to the lateral liner  12  and the main liner member  12  both before and after the curing step.   The adhesive has the properties of being sufficiently flexible to fit around the juncture so that it hugs both the lateral liner  12  and the main liner assembly  14 .   The adhesive has the properties of being sufficiently elastic to permit the adhesive to stretch with the main/lateral liner  10  to engage both the lateral liner  12  and the main liner member  14 .   The adhesive is thermoset so that the exothermic reaction of the resin as it cures and hardens does not affect the adhesive and cause the adhesive to separate from the main liner  14  or the lateral liner  12 .   The adhesive can be extruded in a bead, applied with a trowel, or sprayed.       
 
         [0027]    As shown in  FIG. 3 , curing agent holder  52  having a curing agent  54  is provided for curing the adhesive collar  32  to cause it to become a solid or a material that is rubbery like in substance. Examples of curing agents which may be used to cure the adhesive collar  32  are heat, light, including ultraviolet light, water, sonar, or electricity. While specific examples of curing agents have been given, it should be appreciated that the present invention contemplates others that accomplish the goal of curing the adhesive collar  32 . Therefore, the curing agent holder  52  may be a light source, a heat source, a water source, a sound source, an electrical source or the like. The juncture is preferably cured after the liquid adhesive  30  is applied so that the adhesive collar  32  can flow to both the lateral flange  34  and the main flange  36 . 
         [0028]    Other compounds of different manufacturers or model numbers may be used which meet the specifications above as to viscosity, adherence, and flexibility. While the preferred adhesive should also have elasticity and be thermoset, these are not absolute conditions and a non-elastic or thermoplastic adhesive could be used. 
         [0029]    A rotatable table  38  is shown in  FIGS. 1 and 3 . The table  38  is provided with a centralized rotatable support  40 . An opening  42  is provided at the central portion or located outwardly from the central portion of table  38 . An inflatable plug  44  is provided with an inflation device  46  that extends within opening  42 . The size and shape of the inflatable plug  44  fits within the lateral liner  12 . Preferably, the plug  44  is inflated so that it stretches the main/lateral liner assembly, particularly at the juncture between the main and lateral portions of the liner assembly  10  to simulate the stretching of the liner. The lateral liner  12  is normally undersized and then stretches to remove any wrinkles when installed. 
         [0030]    The main/lateral liner assembly is preferably formed as follows: First the liner assembly  10  is constructed with the lateral liner  12  and the main liner  14  in separate pieces. The lateral liner  12  is then constructed with the lateral liner  12  being formed into a cylinder or other shape, and the stitches  24  are stitched together. The strip of polymer or other tape is then formed over the stitches  24  to create an airtight seal. The lateral liner  12  is inserted into the opening  16  within the main liner member  14  and the stitches  18  are inserted to join the lateral liner  12  to the main liner member  14  at the central opening  16 . The angle may be at 90° or it may be at another angle to accommodate a Y-shaped pipe connection. 
         [0031]    The liner assembly  10  is placed over a table  38  with the main liner member  14  engaging the table top and with the aperture  42  located below the lateral liner  12 . The lateral liner  12  extends upwardly with the longitudinal axis extending upwardly along a longitudinal axis  48 . The main liner member  14  surrounds the lateral liner  12  around central opening  16 , and extends horizontally along a longitudinal axis  50 . 
         [0032]    The plug  44  is inflated by inflation device  46  to cause the liner assembly to stretch about the junction between the lateral liner  12  and the main liner member  14 . The inflation device  46  inflates the plug  44  into the lateral liner  12  and causes it to stretch so that it has no wrinkles. The table  38  supports the main liner member  14  with the lateral liner  12  extending in an upstanding position. Other tables and inflation devices may be utilized without detracting from the invention. 
         [0033]    The bottle  28  is used to spread the liquid adhesive  30  all around the juncture of lateral liner  12  and the main liner member  14  on the resin impermeable coated sides  20 ,  22  of the liners. This liquid adhesive  30 , while in an uncured state, is somewhat viscous. The liquid adhesive  30  forms an adhesive collar  32  having a lateral flange portion  34  that engages the resin impermeable coating  20  of the lateral liner  12  and a main flange portion  36  that engages the resin impermeable coating of the main liner member  14 . The adhesive clings and adheres to the coatings  20 ,  22  to form an air tight bond at the juncture. Finally, the adhesive collar is exposed to the curing agent  54  to cure the liquid adhesive  30  into a desired material which is thermoset, pliable, and which creates an air tight seal at the juncture of the lateral liner  12  and the main liner member  14 . 
         [0034]    Wrinkles are often present in prior art main/lateral liner assemblies. The liner assembly  10  does not have wrinkles therein, as the liner assembly  10  is pre-stretched so as to be wrinkle free at the time the liquid adhesive  30  is applied. 
         [0035]    The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.