Abstract:
An apparatus and method that accelerates curing of resin in a liner for a buried pipe includes an air inversion unit connected to an air compressor. The apparatus includes an inversion head with an interior inflatable plug. The plug, when inflated, creates a substantially airtight seal thereby maintaining pressure within the liner tube. The inversion head can then be removed from the liner inversion apparatus and a curing cap can be installed. To improve the wetting process, a vacuum head is installed at the inversion head and connected to a vacuum source. One end of the liner tube is attached to the inversion head and curable resin is poured into the opposite end. Vacuum pressure is applied to assist in the movement of the resin through the liner tube, ensuring uniform saturation. The resin is mechanically manipulated through the liner tube as the vacuum pressure is applied.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 to provisional application Ser. No. 61/603,360, filed Feb. 26, 2012, which is herein incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to liners that are used to repair buried pipes without excavation. More particularly, but not exclusively, it relates to an apparatus and method that reduces the amount of time required to complete such repairs. 
       BACKGROUND OF THE INVENTION 
       [0003]    Methods of rehabilitating damaged pipes by inverting a tubular liner impregnated with curable resin are known. The known methods of installing a liner to repair a buried pipe, while it remains underground, involve inserting a liner into the pipe and forcing the liner into engagement with the inner walls of the pipe by inflating a bladder. The liner is impregnated with curable resins prior to insertion and the bladder must remain inflated until the resin cures. The time required for the resin to cure, however, ranges from three to eight hours, depending upon ambient temperatures. 
         [0004]    Thus, there is a need in the art for an apparatus and method that provides a shorter curing time regardless of ambient temperatures. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore a primary object, feature, and/or advantage of the present invention to provide a method and system for identifying a product. 
         [0006]    It is another object, feature, and/or advantage of the present invention to provide an inversion head that can be attached to vacuums, fluid sources, and curing heads quickly and easily to repair a damaged section of pipe. 
         [0007]    It is yet another object, feature, and/or advantage of the present invention to provide an inflatable plug connected to an inversion head to plug an inflated liner to allow a different attachment to be attached to the inversion head. 
         [0008]    It is still another object, feature, and/or advantage of the present invention to provide a vacuum source attached to the inversion head to aid in impregnating a liner with a material capable of curing and hardening. 
         [0009]    These and/or other objects, features, and advantages of the present invention will be apparent to those skilled in the art. The present invention is not to be limited to or by these objects, features and advantages. No single embodiment need provide each and every object, feature, or advantage. 
         [0010]    The long-standing but heretofore unfulfilled need for an apparatus and method that shortens resin-curing times is now met by a new, useful, and non-obvious invention. The apparatus includes an inversion head with an interior inflatable bladder. The bladder, when inflated, creates a substantially airtight seal thereby maintaining pressure within the liner tube. The inversion head can then be removed from the liner inversion apparatus and a curing cap can be installed. 
         [0011]    To improve the “wetting process,” a vacuum head is installed in the inversion head and connected to a vacuum source. One end of the liner tube is attached to the inversion head and curable resin is poured into the opposite end. Vacuum pressure is applied to assist in the movement of the resin through the liner tube ensuring uniform saturation. The resin is preferable mechanically manipulated through the liner tube as the vacuum pressure is applied. 
         [0012]    According to an aspect of the invention, a method of repairing a damaged section of a pipe is provided. The method includes providing a liner having an open first end and a substantially closed second end, impregnating the liner with a material capable of curing and hardening, and inverting the liner into the pipe with an inversion head. The first end of the liner is attached to a portion of the inversion head. The method also includes inflating the liner to press the liner against the wall of the pipe, inflating a plug at least partially within the inversion head to substantially close the open end of the liner at the inversion head, and allowing the material to cure and harden. 
         [0013]    According to another aspect of the invention, an assembly for repairing a damaged section of a pipe is provided. The assembly includes an inversion head having an intake end and an opposite discharge end, and a liner having an open first end and a substantially closed second end, the first end attached to the discharge end of the inversion head. The intake end of the inversion head is configured to removably attach to an inversion member for inflating the liner, and a curing head for curing a material capable of curing and hardening that is impregnated in the liner. 
         [0014]    According to yet another aspect of the invention, a method of repairing a damaged section of a pipe is provided. The method includes providing a liner having an open first end and a substantially closed second end, attaching the open end of the liner to a discharge end of an inversion head, impregnating the liner with a material capable of curing and hardening by applying vacuum pressure at an intake end of the inversion head, inverting the liner into the pipe by a fluid source attached to the intake end of the inversion head, inflating the liner to press the liner against the wall of the pipe, inflating a plug at least partially within the inversion head to substantially close the open end of the liner at the inversion head, and allowing the material to cure and harden. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of an illustrative curing cap. 
           [0016]      FIG. 2  is a side plan view of an illustrative curing cap. 
           [0017]      FIG. 3A  is a side plan view of an inversion head, with an un-inverted tubular liner positioned thereon. 
           [0018]      FIG. 3B  is a side plan view of an illustrative curing cap installed in an inversion head, which is in turn installed in the open end of an liner tube. 
           [0019]      FIG. 4A  is a side plan view of an illustrative curing cap installed in an inversion head with the flexible tube extending there through. 
           [0020]      FIG. 4B  is a side plan view of an illustrative curing cap installed in an inversion head with the flexible tube extending there through and into the lumen of the tubular liner. 
           [0021]      FIG. 5  is a diagrammatic view of an illustrative manifold. 
           [0022]      FIG. 6A  is a diagrammatic view of an alternative inversion head. 
           [0023]      FIG. 6B  is a diagrammatic view of an alternative inversion head. 
           [0024]      FIG. 7  is a diagrammatic view of a vacuum head installed in the intake of an inversion head. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    While the present invention is shown for use with sewer pipeline repair, it should be appreciated that the invention can be utilized for repairing other types of pipes, ducts, tunnels and shafts, such as gas, water, oil, steam and compressed air conduits.  FIGS. 1 and 2  depict an illustrative embodiment of a curing cap or head, which is denoted as a whole by the reference numeral  10 . The curing cap  10  includes a substantially circular body  12  having an outer side  12   a  and an inner side  12   b.  The outer side  12   a  further includes an inflation port  14 , a curing port  16 , and a discharge port  18 . All ports are preferably arranged to provide unidirectional fluid communication between the outer side  12   a  and the inner side  12   b  of the circular body  12 . The inner side  12   b  of the circular body  12  is received by an intake  22  of inversion head  20  ( FIG. 3A ). The discharge end  24  releasably engages the interior of the open end  26   a  of the liner tube  26 . 
         [0026]    Two types of liner tubes are commonly used. The first type of liner comprises a felt or fiberglass lining, having a substantially closed end and an opposite open end, and being impregnated with a curable resin. The second type includes a lining composition of two (2) main layers; a first layer comprising an inflatable bladder having a substantially closed end and an opposite open end, and a second layer of felt or fiberglass lining that is impregnated with a curable resin. 
         [0027]    The liner tube  26  preferably comprises a resin-absorbent layer, such as a felt layer ( 26   b ), as well as a resin impervious layer ( 26   c ). The resin impervious layer may comprise a rubber, elastomer, or plastic, as is known in the art. The felt layer is adapted to absorb a resin or grout material, and the plastic layer is adapted to provide an impervious, smooth, and continuous surface. Prior to inverting the liner tube, the plastic layer is located on the outside of the liner tube and the felt layer is located on the inside. During the inversion process (described below), the liner tube  26  is inverted such that the felt layer is on the outside of the liner tube and the smooth plastic layer is on the inside of the liner tube. Use of an impermeable coating on the liner tube allows the liner tube to be inflated and inverted without the use of a separate bladder. However, the invention also contemplates that a bladder can be used, which can negate the need for the impervious layer of the liner. In embodiments using an inflatable bladder, the bladder overlies the felt lining and can contact with plastic layer  26   c.  After inversion, the bladder will be generally within the liner, with the felt layer of the liner against the wall of the pipe. 
         [0028]    Prior to inversion, the intake  22  of the inversion head  20  is connected (via a tubular conduit) to a liner dispensing unit (which normally include a source of pressurized air or other fluid). The dispensing unit holds a length of resin soaked liner prior to delivery. During inversion, the air or other fluid under pressure flows through the system from the dispensing unit towards inversion head  20 . 
         [0029]    As shown in  FIG. 3A , the open end  26   a  of the liner tube  26  is fitted over the discharge end  24  of the inversion head  20  and is secured in place to create an airtight connection therearound, ensuring the air under pressure causes the closed leading end of the liner tube  26  (not shown) to follow a path of travel through the curing cap  20  into the interior or lumen of the pipe, thereby inverting said liner as said closed end is propelled to the distal end of the pipe by said fluid under pressure (see  FIG. 3B ). 
         [0030]    Accordingly, the liner tube  26  is fully inverted along its entire extent when the closed end of the liner tube  26  reaches the distal end of the pipe. The impervious layer now forms the interior surface of liner tube  26  and the resin-impregnated outer layer now forms the exterior layer, which is pressed against the inner sidewalls of the pipe by the pressure of said gaseous or liquid fluid. 
         [0031]    Fluid, such as air or steam, from the inversion compressor further causes the liner  26  (or bladder/liner combination) to expand radially so that the resin-impregnated portion of the liner  26  comes into contact with the interior of the pipe to be repaired. Air pressure is continued against the interior of the liner (or inflatable bladder) to force the resin impregnated or coated surface of the liner  26  into contact with the interior of the pipe. 
         [0032]    Once the liner tube  26  is fully inverted, the inversion head  20  is uncoupled from the dispensing unit and compressed air source. Turning now to  FIG. 4A , a curing cap  10  is then coupled with the intake  22  of the inversion head  20  ( FIG. 3B ). An inflation port  14  is connected to an air compressor (not shown) via an airline  14   a.  Air from the compressor maintains the pressure within the liner  26  to keep the resin impregnated portion or layer ( 26   b ) of the liner  26  in contact with the interior of the pipe. 
         [0033]    The curing port  16  is connected, via a flexible curing tube  16   a,  to a manifold  30  (see  FIG. 5 ), which is in turn in fluid communication with a heated fluid source and an air compressor (not shown). In an alternative embodiment, however, it is possible to use a single air compressor connected to the manifold to provide connections to both the inflation port  14  and the curing port  16 . The curing port  16  is preferably of a slip-ring configuration, but can be adapted for any configuration that allows the curing tube  16   a  to slide through the curing port  16 , while maintaining a substantially fluid-tight seal. 
         [0034]    The drainage port  18  is also connected to the manifold  30  and provides fluid communication, via a drainage line  18   a,  from the interior of the pipe outward to the manifold  30 . 
         [0035]    The manifold  30 ,  FIG. 5 , includes a heat inlet  32 , an air inlet  34 , and an outlet  36 . The heat inlet  32  is in fluid communication with a heating source, which provides heated fluid (i.e. hot water or steam) to the system. The flow of heated fluid into the system is controlled by a heat valve  32   a,  and the temperature and/or pressure of the heated fluid is monitored by a gauge  32   b.  The air inlet  34  is in fluid communication with a drainage air compressor, which provides air, under pressure, to the system. The flow of air under pressure into the system is controlled by an air valve  34   a,  and the temperature and/or pressure of the air is monitored by a gauge  34   b.  As previously stated, the drainage air compressor can be replaced by the inversion air compressor using linkages as known in the art. Both the heat fluid inlet  32  and the air inlet  34  are in open fluid communication with the outlet valve  36 . For example, when the heat valve  32   a  is open, heated fluid is permitted to pass through the manifold  30 , thereby exiting the outlet  36  and entering the system via the curing tube  16   a.    
         [0036]    The manifold  30  also includes a drainage inlet  38 , connected to the drainage line  18 , which further comprises a drainage valve  38   a  and a temperature/pressure gauge  38   b.  Fluids leaving the system via the drainage line  18   a  can be monitored via the gauge  38   b  and disposed of when safe through the drainage outlet  38   c.    
         [0037]    Another aspect of the inventive method occurs after the liner tube  26  has been inverted and is being pressed against the sides of the pipe under pressure. This aspect includes the steps of inserting a curing tube  16   a  into the lumen of the liner tube  26 , opening the heat valve  32  so that heated fluid flows through the manifold  30  via the outlet  36 , into curing the curing tube  16   a,  and into the lumen of the liner tube  26 . 
         [0038]    The curing tube  16   a  is an elongate flexible tube including a substantially spherical guide  17  at its distal end. The curing tube  16   a  also includes a series of perforations  19  proximal to the spherical guide  17 . Once the liner tube  26  is fully extended, the curing tube  16   a  is fed through the curing port  16 , thereby advancing the guide  17  through the lumen of the liner tube  26 . The substantially spherical shape of the guide  17  allows the distal end of the tube to easily navigate corners and bends. Once properly positioned, the heated fluid passes through the curing tube  16   a  and out the perforations  19  into the lumen of the liner tube  26  near its distal end. This ensures that the liner tube  26  is heated from the distal (closed) end toward the proximal (open) end. 
         [0039]    As the heated fluid fills the lumen of the liner tube from the distal end, the air under pressure used to invert the liner tube is permitted to escape through the drainage port  18  and back towards the manifold  30  via the drainage line  18   a.  The gauge  38   a  is monitored as the fluids (air under pressure, steam or hot water) pass therethrough. When the gauge shows that the temperatures of the drainage fluids are substantially equal to the temperature of the heated fluid entering the system, this indicates that the heated fluid has reached the proximal end of the liner tube  26 . It can now be assumed that the liner tube  16  is substantially filled with said heated fluid. The heat valve  32   a  and the drainage valve  38   a  can then be closed, fully or partially, so that the liner tube  26  is not over-pressurized. The resin cures within a significantly abbreviated time because the heat of the heated fluid is conducted by the inflatable bladder (or plastic liner layer  26   c ) into the resin-impregnated layer  26   b,  where it acts as a catalyst. 
         [0040]    When the resin has sufficiently cured, the drainage valve  36   a  is opened to allow the lumen of the liner tube to be emptied of the added fluid. To facilitate drainage, the air valve  34   a  is opened, forcing air under pressure through the perforations  19  in the distal end of the curing tube  16   a.  This air under pressure forces any remaining heated fluid through the drainage port  18 , through the line  18   a  and into the drainage inlet  38   a.  The inversion head  20  and curing cap  10  can be removed once substantially all heated fluids are removed from the lumen of the liner tube  26 . 
         [0041]    According to an aspect of the invention shown generally in  FIG. 6A , the inversion head  20  can be adapted with an inflatable internal plug  29  disposed interiorly and connected to a source of pressurized fluid (preferably air). The plug  29  can be positioned within the inversion head  20  and can also be attached to a portion of the inversion head  20 . After the liner tube  26  has been inverted and pressurized, the plug  29  is inflated, thereby forming a substantially airtight seal at the open end of the liner. Once the plug  29  is inflated, it is possible to remove the inversion head  20  from the liner-dispensing unit without maintaining pressure within the liner tube  26 . The curing cap  10  (or other cap) can then be attached to the inversion head  20 , as described above. 
         [0042]    The plug  29  can be recessed within a groove in the interior wall of the inversion head  29 . This arrangement permits the liner tube  26  to travel smoothly through the inversion head as it is inverted. The plug  29  can be annular, but can be inflated to occlude the interior of inversion head  20 , not unlike a balloon ( FIG. 6B ). 
         [0043]    Alternatively, the plug  29  can be any mechanical means of occluding the interior of the inversion head  20  to provide a substantially airtight seal. Examples include an iris-like device, a ball valve, a check valve, a pipe interrupter, or the like. 
         [0044]    Prior to use, the curable resin material is applied to the liner tube  26  during a “wetting out” process. The liner tube  26  is attached to the inversion head  20 , with the felt or resin-absorbent layer on the interior. Resin is then poured into the opposite end of the liner tube  26 . A roller is used over the liner to ensure that the resin is spread evenly along the length of the liner tube  26 . An aspect of the invention improves on this method by the use of a vacuum head  100  attached to the inversion head  20 , as is shown in  FIG. 7 . The vacuum head  100  can be attached at the intake  22  of the inversion head. 
         [0045]    During the wetting or wetting out process, the vacuum head  100  is attached to the intake  22  of the inversion head  20 . After the resin is poured into the liner tube  26  and after or while the roller is rolled over the liner, negative (vacuum) pressure is provided to the interior of the liner tube  26  via the vacuum head  100 . The negative or vacuum pressure can be provided by a vacuum source (not shown). This can be any negative pressure source, such as a vacuum or the like. The addition of the vacuum source and pressure helps ensure the even spreading of the resin throughout the liner tube  26 . Vacuum (negative) pressure can be used with or without the use of a roller, as well. Once the liner tube  26  is impregnated or saturated with resin, the vacuum head  100  can be removed from the intake  22  of the inversion head  20 , and the fluid source and/or curing head can be attached, as described above. 
         [0046]    All documents cited herein are incorporated herein by reference in their entirety. The invention is illustrated by the preceding embodiments. These embodiments are provided to aid in the understanding of the invention and are not to be construed as a limitation with regard to the arrangement of the parts shown in the figures or the order of steps provided. 
         [0047]    It will thus be seen that the objects set forth above, and those made apparent from the foregoing disclosure, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing disclosure or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
         [0048]    The foregoing description has been presented for purposes of illustration and description, and is not intended to be an exhaustive list or to limit the invention to precise forms disclosed. It is contemplated that other alternative processes obvious to those skilled in the art are considered to be included in the invention. The description is merely examples of embodiments. It is understood that any other modifications, substitutions, and/or 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 the stated objectives.