Abstract:
A new apparatus for repairing a damaged portion of a pipe includes a liner having a tubular sleeve of resin absorbent material that is capable of being stretched circumferentially and a plastic film laminated to an exterior surface of the sleeve. The plastic film contains resinous material in the liner until the liner is stretched circumferentially to thereby breech the integrity of the plastic film and expose the resinous material to a damaged section of pipe in need of repair. A method of lining a damaged section of pipe using the liner is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 of a provisional application Ser. No. 61/155,742 filed Feb. 26, 2009, which application is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an apparatus and method for repairing pipe, such as underground sewer pipe and the like. 
         [0003]    Prior methods for repairing damaged sections of pipe include moving a liner tube impregnated with a resinous material capable of curing and hardening to a position within the pipe where the damaged portion is located. Once the liner tube is positioned within the host pipe, it is pressurized, causing the liner to press against the interior wall of the host pipe, and the liner is cured by applying heat, such as with steam or hot water. These liners can also be cured at ambient temperatures by a chemical mixture which generates an exothermic reaction or by ultraviolet light. The liner tube forms an interior liner in the pipe for the pipeline being repaired. Such a process is commonly known as cured-in-place pipelining. 
         [0004]    The liner tube is positioned within the pipe by pulling, pushing or inverting the liner. Pulling or pushing a liner into position within a pipe can be an efficient process, particularly in situations where the liner must only travel a short distance and need not navigate significant bends in the pipe. Typically, a flat sheet liner is wrapped around an inflation plug to form a tube with the longitudinal edges of the sheet overlapping. The inflation plug with liner is then pushed or pulled into position adjacent the damaged section of pipe. 
         [0005]    Although a pull-in-place or push-in-place installation is feasible in many instances, problems remain. For example, prior art lining tubes are typically made of a fabric material that is resin absorbent. Once the resin is applied to the liner, there is nothing around the outside of the liner to contain the resin. Consequently, resin is wiped off of the liner when the liner rubs against the interior of the host pipe as the liner is either pulled or pushed into position. Workers must also take great care so as to not come into contact with the resin and also avoid contaminating the exposed resin impregnated liner. 
         [0006]    Prior art liners pushed or pulled in place are also not well suited for lining at bends in the pipeline. Flat sheet liners with overlapping edges are not capable of stretching or expanding sufficiently to avoid folds in the liner when pressed against the interior of the host pipe. In addition, flat sheet style liners must be banded, strapped, tied or otherwise attached with fasteners to the inflation plug to avoid falling off the plug prior to inflating the plug and pressing the liner against the interior of the host pipe. 
         [0007]    In light of the foregoing, the primary objective of the present invention is to provide an improved method and apparatus for lining pipe. 
         [0008]    Another objective of the present invention is to provide a new resin absorbent liner that contains the resin in the liner prior to stretching the liner and pressing it against the interior of the host pipe. 
         [0009]    Another objective of the present invention is to provide a new lining apparatus for pull-in-place or push-in-place applications that prevents resin from being wiped off of the liner as it is moved into the pipe, yet allows the resin to contact the interior of the host pipe once the liner is expanded or stretched under pressure. 
         [0010]    Another objective of the present invention is to provide a new lining apparatus and method for effectively lining at bends and turns in the pipeline. 
         [0011]    A still further objective of the present invention is to provide a new lining apparatus which is economical to manufacture, durable in use and efficient in operation. 
       SUMMARY OF THE INVENTION 
       [0012]    According to one aspect of the present invention, an apparatus for repairing a damaged portion of a pipe is provided. The apparatus includes a liner with a tubular sleeve of a resin absorbent material that is capable of being stretched circumferentially and a plastic film disposed on an exterior surface of the sleeve. Once the liner is impregnated with a resinous material, the plastic film contains the resin and prevents the resin from being wiped off of the liner while outside of the pipe and as the liner is being moved to an operative position adjacent the damaged section of pipe in need of repair. Stretching the liner circumferentially toward the damaged section of pipe breeches the integrity of the plastic film to expose the resinous material and tubular sleeve to the damaged section of the pipe. 
         [0013]    In a preferred form of the invention, the plastic film is a TPU or like polymer film with a wall thickness of approximately 1-2 mils that is laminated to the sleeve. The preferred tubular sleeve is also capable of being stretched to a diameter of at least approximately 100% greater than its non-stretched diameter. Allowing the sleeve to stretch to such an extent allows the sleeve to conform to the shape of the pipe even at bends and curves in the pipeline without creating undesirable folds in the liner. 
         [0014]    Another aspect of the invention is a new method of lining a damaged section of pipe using a liner having a tubular sleeve of resin absorbent material and a plastic film laminated to an exterior surface of the sleeve. The liner is impregnated with a resinous material capable of curing and hardening. The liner is moved into the pipe to a position adjacent the damaged section of the pipe. Once in position, the liner is stretched circumferentially toward the damaged section of pipe to thereby breech the integrity of the plastic film and expose the resinous material in the tubular sleeve to the damaged section of the pipe. The liner is pressed against the damaged section of a pipe, allowing the resinous material to cure and harden. 
         [0015]    In a preferred form of the method, the liner is positioned on an inflatable plug with a substantially non-stick bladder material located therebetween. The tubular non-stick bladder material is banded to the front end of the inflatable plug such that the bladder material peels away from the cured liner as the inflatable plug is removed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of a liner from a preferred embodiment of the present invention. 
           [0017]      FIG. 2  is a sectional view of the liner in  FIG. 1  taken along line  2 - 2  in  FIG. 1 . 
           [0018]      FIG. 3  is a sectional view of the preferred liner of the present invention ready for impregnation of a thermal-set resin using a vacuum process. 
           [0019]      FIG. 4  is a schematic view showing the vacuum impregnation process. 
           [0020]      FIG. 5  is a perspective view of the preferred liner mounted on an inflatable plug. 
           [0021]      FIG. 6  is a cross-sectional view of the device shown in  FIG. 5  taken along line  6 - 6  in  FIG. 5 . 
           [0022]      FIG. 7  is a schematic view illustrating a preferred method of the present invention for repairing a portion of a damaged pipeline extending between two manholes. 
           [0023]      FIG. 8  is a sectional view at the damaged section of pipe after the liner has been stretched and pressed against the interior of the pipe. 
           [0024]      FIG. 9  is a sectional view similar to  FIG. 8 , showing the liner pressed against a bend in the pipeline. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]      FIG. 1  shows a perspective view of a preferred liner  10  of the present invention. The liner  10  is formed by a tubular sleeve  12  including a fabric fiber material which can preferably be stretched circumferentially up to at least approximately 100% of its non-stretched diameter. The sleeve  12  is preferably formed from a sheet of material stitched about its longitudinal edges. A preferred fabric for the sleeve  12  is a material known as “stitch bond” distributed by LMK Enterprises, Inc. of 1779 Chessie Lane, Ottawa, Ill. 61350. 
         [0026]    The preferred liner  10  also includes a plastic film  14  laminated to an exterior surface of the tubular sleeve  12 . The preferred plastic film  14  has a thickness of approximately 1-2 mils and is made of TPU, but could be made of PVC or a similar polymer film. The plastic film  14  is cured and then laminated to the sleeve  12  using an adhesive or glue as is known in the art. 
         [0027]    The sleeve  12  is impregnated with a resin, preferably a thermal-set resin, which is forced into the fabric fibers. A method of impregnating the sleeve  12  with the resin is shown in  FIGS. 3 and 4 . More particularly, the fabric fibers of the sleeve  12  are on the inside of the sleeve with the plastic film  14  on the exterior of the sleeve  12 . One end of the sleeve  12  is connected to a vacuum bag using tape or other adhesive. The opposite end of the vacuum bag  16  is connected to a vacuum hose  18  through a threaded coupling  20 . The vacuum hose  18  is connected to a vacuum source  22 , as seen in  FIGS. 3 and 4 . A wick  24  extends through the length of the vacuum bag  16  and functions to expel air from the sleeve  12  during the resin impregnation process. 
         [0028]    As shown in  FIG. 4 , a slug  27  of resin is introduced into the open end of the sleeve  12  and is forced through the sleeve so as to impregnate the fabric fibers. A pipe  26  may be rolled over the sleeve  12  so as to push the resin  27  through the sleeve. Simultaneously or alternatively, the vacuum source  22  can be activated to pull the resin slug  27  through the sleeve  12 , thereby coating and impregnating the fabric fibers with the resin. After this resin impregnation process is completed, the sleeve  12  is in the form of a flattened tube with the plastic film  14  still on the outside and the resin coated fibers on the inside. As an alternative to the vacuum impregnation process, the resin can be poured into the liner tube and then pressed into the fibers by a person or other means in a manual impregnation process. 
         [0029]    Once the liner  10  is impregnated with resin, the plastic film  14  on the outside of the sleeve  12  helps to contain the resin and prevent it from being wiped off or coming into contact with persons or objects prior to stretching the sleeve  12  and pressing the liner  10  against the interior of host pipe at the damaged section of pipe. The plastic film  14  is very thin to begin, preferably 1-2 mils thick. As the sleeve  12  stretches or expands radially outwardly, the plastic film  14  becomes even thinner and eventually the stretching of the sleeve  12  breeches the structural integrity of the plastic film  14 , which becomes extremely porous. This unique characteristic of the plastic film  14  helps contain the resin in the liner  10  prior to stretching the tubular sleeve  12  and pressing the liner  10  against the damaged section of pipe. 
         [0030]    The liner  10  is preferably installed in the pipe by using an inflatable plug. Inflatable plugs normally include an inflatable rubber sleeve secured between end plates. Inflatable plugs for installing cured-in-place liners are well known in the art. For example, push-type and pull-type inflatable plugs are available from Logiball, Inc. of 440 Papin Street, Quebec, QC G1P3 T9 and 21 Long Pond Road, Jackman, Me. 04945. Push-type inflatable plugs are often used when the liner must only be moved a relatively short distance within the pipe or there is no convenient downstream manhole or other access point from which to pull in the plug. For example, a push-type inflatable plug may be used to push a liner through a cleanout and into a lateral sewer pipe for a spot repair on a damaged portion of the lateral pipe. A rigid hose assembly can be used to push the inflatable plug with liner through the pipe, as is known in the art. Alternatively, an air hose with fiberglass push rod disposed therein can be used. The fiberglass push rod provides for greater stiffness when pushing the plug long distances, and the push rod can be sized so as to allow for air to pass through the hose and inflate the plug. A sealing gland with O-ring allows the hose with rod to slide forward within the plug into contact with the leading end of the plug, which aids in pushing the plug through the pipe. Similarly, the hose with rod can be pulled back until stopped by a retaining ring at the opposite end of the plug, which aids in pulling the plug out of the pipe after installation of the liner. 
         [0031]    After the liner  10  has been “wet out” with resin, the liner is pulled over an inflatable plug  28 . A liner  10  mounted on the inflatable plug  2  is shown in  FIG. 5 . The elastic properties of the liner  10  allow it to stay in place on the inflatable plug  28  without the use of bands, straps, strings or other fasteners. 
         [0032]    A cross-sectional view of the assembly in  FIG. 6  shows a tubular sleeve of non-stick bladder material  30  disposed between the inflatable plug  28  and the liner  10 . The purpose of the non-stick sleeve of bladder material  30  is to facilitate removal of the plug  28  after the liner  10  has cured and hardened in the pipe. The non-stick bladder material is preferably formed from a fiber reinforced non-stick plastic material, which includes a scrim reinforcing fabric coated with a translucent or semi-transparent thermo plastic elastomer, such as a thermo plastic polyolefin (TPO) or vulcanizate (TPUV). The preferred non-stick bladder material is disclosed in application Ser. No. 12/026,209, the contents of which are incorporated herein by reference. 
         [0033]    The non-stick sleeve  30  is preferably attached to the inflation plug  28  by banding a non-stick sleeve to the front end of the plug. Banding the non-stick sleeve  30  to the front end of the plug  28  maintains the non-stick sleeve in place as the inflatable plug is pulled or pushed into position along the pipe. Banding only at one end also causes the non-stick sleeve  30  to invert during removal of the inflation plug  28 , which facilitates separation of the non-stick sleeve  30  from the liner  10  once the liner is cured and hardened in the pipe. 
         [0034]      FIG. 7  shows a sectional view of a main sewer pipe  32  in communication with an upstream manhole  34  and downstream manhole  36 . To perform a spot repair in a main sewer pipe  32  using a pull-in-place process, the inflatable plug  28  with liner  10  is introduced into the main pipe through one of the manhole openings. The plug  28  is drawn into the pipe  32  by means of a winch cable attached to the front end of the plug and extending through an upstream manhole or other access point. As the inflatable plug  28  with liner  10  moves through the pipe  32 , the plastic film  14  prevents the resin from wiping off on the pipe. 
         [0035]    Once the inflation plug  28  with liner  10  is moved into operative position adjacent the damaged section of pipe, the inflation plug is inflated with air or other liquid under pressure from a convenient fluid source, causing the liner to stretch radially outwardly toward the interior of host pipe. Stretching the liner  10  breeches the structural integrity of the plastic film  14  on the outside of the sleeve  12 . This allows the resin and sleeve  12  to become exposed to the host pipe. The liner  10  continues to stretch under pressure and is pressed against the interior of the host pipe, allowing the liner to cure and harden. The inflation plug  28  remains inflated while the resin cures. Upon curing of the resin, the liner  10  is bonded and mechanically adhered to the interior of the pipe  32 . The expansion of the inflatable plug  28  assures that no angular spaces reside between the liner  10  and the host pipe. Also, the stretching of the sleeve  12  from a first unstretched diameter to an enlarged diameter matching the contours of the interior of the host pipe precludes undesirable folds in the liner  10 . The liner  10  is preferably sized to stretch in the pipe to a diameter at least 50% greater than the pre-inflation diameter. In a most preferred form, the liner  10  is sized approximately half of the internal diameter of the host pipe. The liner  10  should stretch such that it conforms to the shape of the pipe without folds in the liner. Stretching the sleeve  12  also enables the liner  10  to be used at bends or turns in the pipe. This is illustrated in  FIG. 9 . 
         [0036]    After the resin cures, the inflation plug  28  is deflated and removed from the cured liner  10 . Removing the inflation plug  28  causes the non-stick sleeve  30  to invert and pull away from the interior of the cured liner  10 . 
         [0037]      FIG. 8  is a sectional view of the lining apparatus with the inflatable plug  28  inflated, pressing the liner  10  against the host pipe. As illustrated in  FIG. 8 , the plastic film previously on the outside of the sleeve has lost its structural integrity and becomes part of the resin/liner material mechanically adhered to the host pipe. 
         [0038]    Although  FIGS. 7 and 8  illustrate a pull-in-place style installation, persons skilled in the art having the benefit of this disclosure will recognize that the lining methods and apparatus disclosed herein are also applicable to push-in-place installations. 
         [0039]    The invention has been shown and described above with reference to 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.