Patent Abstract:
An apparatus and a method for using a bladder in combination with a curable material capable of curing and hardening is disclosed. A curable material capable of curing and hardening is dispensed about an interior wall of a damaged section of a pipe ahead of an inverting end of a bladder. The bladder inverts to push a plate attached to a dispensing unit, pushing the assembly through the pipe, while also compressing the curable material against the interior wall of the pipe. The material is pressed into fractures and the bladder remains inflated until the material cures and hardens, leaving a newly lined pipe. An assembly for forming the lining in the pipe includes a dispensing hose, a dispensing unit, and a bladder.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an apparatus and method for lining an interior surface of a pipe. More particularly, but not exclusively, the invention relates to a method and apparatus for repairing a pipe without the use of a pre-formed liner. 
       BACKGROUND OF THE INVENTION 
       [0002]    One method of repairing a damaged section of a pipe includes spraying or spin casting mortar about the interior of the pipe. The mortar will cure and harden to form a new interior wall at the damaged section of the pipe, lengthening the life of the pipe. However, many problems exist when the mortar is sprayed or spun onto the interior wall of the damaged section of a pipe. 
         [0003]    One problem associated with this method of pipe repair is that while the mortar generally has low viscosity, gravity may cause a portion of the material to sag in the pipe before the mortar is able to fully cure. The sagging mortar will cure away from the damaged section of the wall. The sag would also cause gaps between the mortar and wall, which would allow for water penetration behind the cured mortar. The water may damage the pipe wall, and the mortar would have to be removed and reapplied. 
         [0004]    Additionally, the sagging portion of the mortar will create new obstructions in the pipe. Merely spraying or spin casting the mortar onto the wall of the pipe would create a rough, jagged surface, which, over time, may create blockages in the pipe. Likewise, the application of the mortar by spraying or spin casting would produce a new wall of varying thickness, which would produce weak areas in the pipe. 
         [0005]    Another method presently used for repairing pipes includes the use of a liner tube having a felt layer on its inside and having a protective layer made of polymer or other plastic material on its outside. The liner tube is vacuum-impregnated with a resin mix in what is commonly referred to as a “wet-out” process. Just prior to wetting-out the liner, a catalyst is mixed with the resin so as to activate the resin and cause it to begin curing and hardening. The resin impregnated liner tube is then inverted into the pipe so that the felt layer is inverted from the inside of the tube to the outside. Once the resin cures and hardens, the liner provides a new lining for the pipe. 
         [0006]    One problem with the method is that the catalyst must be mixed with the resin before the liner tube is wet-out and before positioning the liner tube at the damaged section of pipe. Once the catalyst is applied to the resin, the resin begins curing and time is of the essence in order to have the liner tube in place within the pipe to be repaired. If the resin hardens before the liner tube is properly positioned within the pipe, it may require that a portion of the existing pipe be dug up and replaced. If, on the other hand, a resin mix with a longer cure time is used to ensure adequate working time to install the liner, productivity suffers as the crew waits for the liner to cure and harden. 
         [0007]    Accordingly, there is a need in the art for an improved method and means that overcomes the problem of a damaged section of a pipe not being fully repaired by the spraying or spin casting of mortar about an interior of the damaged section of the pipe. There is also a need in the art for a method and means of repairing a damaged section of a pipe that obviates the need of a pre-formed liner. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    It is therefore a principal object, feature, and/or advantage of the present invention to provide an improved method and means for lining a manhole which improves over or solves the deficiencies in the art. 
         [0009]    It is another object, feature, and/or advantage of the present invention to provide an improved means and method for lining a pipe that does not require a pre-formed liner. 
         [0010]    It is another object, feature, and/or advantage of the present invention to provide an improved means and method for lining a pipe that leaves a repaired pipe wall having a smooth surface and a uniform thickness. 
         [0011]    It is another object, feature, and/or advantage of the present invention to provide an improved means and method for lining a pipe that penetrates damages in the pipe to prevent water from seeping into the pipe. 
         [0012]    It is yet another object, feature, and/or advantage of the present invention to provide a method and means for lining a pipe that is more cost-effective than prior methods. 
         [0013]    It is another object, feature, and/or advantage of the present invention to provide a method and means for repairing a pipe that is flexible in allowing any length of lining to be installed during the installation process without pre-fabrication of a liner of a desired length. 
         [0014]    It is still another object, feature, and/or advantage of the present invention to provide an improved method and means for repairing a damaged section of a pipe that does not obstruct the normal use of the pipe. 
         [0015]    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, and no single embodiment need exhibit every object, feature, and advantage. 
         [0016]    According to one aspect of the present invention, a method of repairing a damaged section of a pipe that obviates the need for a pre-formed liner is provided. The method includes dispensing a material capable of curing about an interior wall of the pipe ahead of an inverting end of a bladder. The material is compressed against the wall of the pipe with the bladder. The material is allowed to cure, and then the bladder is removed from the pipe. 
         [0017]    According to another aspect of the present invention, a method of repairing a damaged section of a pipe that obviates the need for a pre-formed liner is provided. The method includes positioning a bladder in the damaged section of the pipe. The bladder is inverted in the pipe. A curable material is dispensed about an interior wall of the damaged section of the pipe with a dispensing unit ahead of an inverting end of the bladder. A plate, operatively attached to the dispensing unit, is pushed with the inverting end of the bladder to move the dispensing unit along the pipe. The curable material is pressed against the wall of the pipe with an exterior surface of the bladder and the curable material is allowed to cure. 
         [0018]    According to another aspect of the present invention, a method of repairing a damaged section of a pipe that obviates the need for a pre-formed liner is provided. A bladder, having an uneven exterior surface along the length of the bladder, is inverted into the damaged section of the pipe. A curable material is dispensed from a dispensing unit about an interior wall of the pipe ahead of an inverting face of the bladder. A plate attached to the dispensing unit is pushed with the inverting face of the bladder to move the dispensing unit along the damaged section of the pipe as the dispensing unit dispenses the curable material. The curable material is then compressed between the exterior surface of the bladder and the interior wall of the pipe, and the curable material is allowed to cure. 
         [0019]    According to another aspect of the present invention, a liner assembly for repairing an interior of a pipe is provided. The liner assembly includes a dispensing hose, a dispensing unit, and a bladder. The dispensing unit is in fluid communication with the dispensing hose. The dispensing unit has a spinning head adapted to dispense a curable material to an interior wall of a pipe and a plate positioned forward of the spinning head. The bladder is adapted to press the curable material dispensed from the dispensing unit against the interior wall of the pipe, with the bladder having an inverting end. The inverting end of the bladder is positioned adjacent the plate of the dispensing unit such that the bladder pushes the plate and corresponding dispensing unit through the pipe as the bladder is inverted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1A  is a schematic view illustrating a preferred embodiment of the present invention utilized for repairing a mainline pipe extending between two manholes. 
           [0021]      FIG. 1B  is a schematic view similar to  FIG. 1A , further illustrating the preferred lining process of the present invention. 
           [0022]      FIG. 2  is an enlarged side view of the dispensing unit for use with the preferred embodiment of the present invention. 
           [0023]      FIG. 3  is an enlarged sectional view of a pressurized reel with bladder loaded therein for use in a preferred embodiment of the present invention. 
           [0024]      FIG. 4  is a sectional view of a sewer pipe with a damaged section of pipe lined according to an alternative embodiment of the present invention. 
           [0025]      FIGS. 5A-5C  are enlarged sectional views, illustrating various forms of a bladder for use in an alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Referring to  FIG. 1A , a main pipe  10  is shown extending between a downstream manhole  14  and an upstream manhole  16 . Lateral pipes  18  extend from the main pipe  10  and extend through the ground  82 . While the present invention is shown for use with sewer pipe repair, the present invention can be utilized for repairing other types of pipe, such as gas, water, oil, steam and compressed air pipe. 
         [0027]    Adjacent the upstream manhole  16  is a pressurized reel  60 . Inside the reel  60  is a bladder  44  connected to a rope  72 . The reel  60  can be pressurized to invert the bladder  44  through the upstream manhole  16  and into the pipe  10 . The bladder  44  would be inverted to a position adjacent a dispensing unit  34 . 
         [0028]    Adjacent the downstream manhole  14  on the ground  82  is a truck  22  having pump  24  and a reservoir  26  mounted thereon. Hose  32  extends from the reservoir  26  to the dispensing unit  34  shown within the pipe  10 . The hose  32  may also include electronic cables for controlling the dispensing unit  34  and for transmitting images from an image device  40  operatively attached to the dispensing unit. The truck  22  also contains image receivers (not shown) for viewing data from the image device  40 . 
         [0029]    As further shown in  FIG. 1A , the hose, also known as a dispensing hose  32 , is wound through a take-up reel  74 , which is adjacent the downstream manhole  14 . The hose  32  is fluidly attached to the dispensing unit  34  located in the pipe  10 , and transports a curable material  28  to the dispensing unit  34 . The curable material  28  is a pumpable material capable of curing and hardening. Examples of materials that may be proper for use with the invention include mortar, grout, and modified liquid materials capable of hardening and producing high flexural and tensile properties. A preferred material for use with the present invention is Permacast, as manufactured by APM Permaform of 6843 N.W. Trail Ridge, P.O. Box 582, Johnston, Iowa 50131-0582, but other model numbers and/or manufacturers may be used as well. 
         [0030]      FIG. 2  is an enlarged side view of one embodiment of a dispensing unit  34  used with the present invention. The dispensing unit  34  comprises a dispensing unit housing  88  for receiving the dispensing hose  32 . Attached to the dispensing housing  88  is a plurality of wheels  42  to allow the dispensing unit  34  to move through the pipe  10 . An image device  40  is operatively attached to the dispensing housing  88  as well. The image device  40  is oriented rearwardly of the dispensing unit  34  to view the dispensing hose slack  80  in the pipe  10 . The image device  40  is also connected to image receivers (not shown) located outside of the pipe  10 , where operators can view the area rear of the dispensing unit  34  in the pipe  10 . 
         [0031]    The dispensing hose  32  extends through the dispensing unit housing  88  and is fluidly connected to a spinning device  36 , which is located forward of the dispensing unit housing  88 . While a spinning device  36  is shown operatively attached to the dispensing unit  34 , it should be appreciated that other application methods may be used to apply the curable material  28  to the interior wall  12  of the pipe  10 . Additionally, a plate  38  is attached to the dispensing unit  34  at a location forward of the spinning device  36 . The plate  38  is attached to the dispensing unit housing  88  by a plate connector  76 .  FIG. 2  shows the plate connector  76  extending through the axis of the spinning device  36 . Attaching the plate  38  in this manner will ensure that the spinning device  36  is able to sling curable material  28  about the full interior periphery of the pipe  10 . However, it may be desired that the plate  38  be connected in another manner, such as below or above the edge of the spinning device  36 . The plate  38  shown in  FIG. 2  comprises a concave shape. However, it should be appreciated that the plate  38  be shaped in many different manners. For example, the plate  38  may be substantially straight or flat, convex, triangular, or any variation thereof. It is only required that the plate  38  be able to engage an inverting end  46  of the bladder  44  to move the dispensing unit  34  through the pipe  10 . 
         [0032]      FIG. 3  is an enlarged sectional view of the pressurized reel  60  with a bladder  44  loaded therein for use in a preferred embodiment of the present invention. The pressurized reel  60  contains an outer cylindrical housing  62  and a center roller  64 . A pressure inlet valve  66  in the housing  62  provides communication from the interior of the housing to a pressure hose  68 . The pressure hose  68  is preferable connected to a pneumatic source of pressurized air; however, other fluids could be used without detracting from the invention. The inlet valve  66  is movable from an open position permitting pressurized fluid (preferably air) to be introduced to the interior of the pressurized reel  60  to a closed position shutting off communication of pressurized fluid from the interior of the pressurized reel  60 . The reel  60  includes an inverting boss  70  on one of its sides upon which may be mounted an inflatable bladder  44 . 
         [0033]    The bladder  44  is preferably formed from a fiber reinforced non-stick plastic material, which allows the bladder  44  to be easily removed from the cured lining material  78  when re-inverted through the pipe  10 . The bladder  44  preferably includes a body formed of a layer of fiber reinforcing material, such as a scrim reinforcing fabric. The layer of fiber reinforcing material is preferably a scrim of Nylon filament knit fibers. The body has an inside coating and an outside coating, both preferably made of a thermoplastic elastomer. An example of a commercial TPE elastomer alloy found suitable is Santoprene® from Exxon. The wall thickness of the bladder is preferably 15-30 mils. 
         [0034]    As further shown in  FIG. 4 , a rope  72  is wound around the center roller  64  within the pressurized reel  60 . Enough rope  72  must be included to traverse the entire length of the damaged area  20  of the pipe  10  to be repaired. A closed end  48  of the bladder  44  is attached to the end of the rope  72 . The bladder  44  is then wound around the center roller  64  until its complete length is taken up. The open end  58  of the bladder  44  is fitted over the boss  70  and is taped or clamped in place so as to have an airtight connection there around. As shown in  FIG. 4 , the open end  58  of the bladder  44  is folded back upon itself much in the same fashion s the peeling off of a sock. 
         [0035]    Referring back to  FIGS. 1A and 1B , the method of repairing a damaged section of a pipe  10  using the present invention will be described. To repair the pipe  10 , the bladder  44  must be properly positioned initially relative to the dispensing unit  34 . A portion of the bladder  44  is inverted and positioned in the upstream manhole  16  adjacent the opening of the pipe  10 . An operator in the manhole  16  can then position the inverting end  46  of the bladder  44  against the plate  38  of the dispensing unit  34 , which has been positioned in the pipe  10  through the downstream manhole  14 . The inverting end  46  of the bladder should be butted against the plate  38 , behind where the curable material  28  is dispensed. The pressure inlet valve  66  is moved to its open position to allow fluid pressure, preferably air, into the interior of the reel  60  such that the bladder  44  inflates and the rope  72  becomes taught. The curable material  28  is then pumped from the truck  22  through the hose  32  and is slung by the spinning device  36  about the interior wall  12  of the pipe  10 . 
         [0036]    Once an operator visually confirms that curable material  28  is dispensing through the spinning device  36 , the fluid pressure in the reel  60  is increased to further inflate the bladder  44 . The bladder  44  will continue to invert with the inverting end  46  of the bladder  44  pushing against the plate  38  of the dispensing unit  34 , creating a liner assembly  30 . The inversion of the bladder  44  against the plate  38  will push the dispensing unit  34  through the pipe  10 , with the liner assembly  30  moving at substantially the same speed through the pipe  10 . The liner assembly  30  essentially moves at the pace of bladder inversion. As the assembly moves through the pipe  10 , the spinning device  36  will continue to sling the curable material  28  against the interior wall  12  of the pipe  10 . While the bladder inverts and pushes the assembly through the pipe, operators view image data sent from the image device  40  on the dispensing unit  34  to view the dispensing hose slack  80  ahead of the dispensing unit  34 . If needed, the hose  32  is pulled taught by the take-up reel  74 . The use of the bladder  44  to move the assembly through the pipe  10  is beneficial to use over the use of control reels. The pushing bladder decreases the amount of devices required, and removes most of the electrical controls needed for control reels. With less parts, there is less chance of problems occurring, which helps to increase productivity of users in repairing the pipes. 
         [0037]    As the bladder  44  inverts through the pipe  10 , the exterior surface  50  of the bladder  44  will compress the curable material  28  against the wall  12  of the pipe  10  to smooth and evenly spread the material about the wall  12 . The assembly will move the through the pipe  10  in the direction generally shown by the arrow  84  of  FIG. 1A . Because the inverting end  46  of the bladder  44  is positioned a short distance from the spinning device  36 , the exterior surface  50  of the bladder  44  will compress the curable material  28  almost instantaneously after the material has been applied to the wall  12 . The almost instantaneous pressing of the bladder ensures that the material will not have an opportunity to drip or flow away from the top of the pipe, to help evenly spread the material. As the assembly moves down the pipe  10 , the image device  40 , oriented to a location ahead of the dispensing unit  34 , will transmit image data to outside of the pipe  10 . The image data will be used to determine the amount of slack  80  of the dispensing hose  32 . As the slack builds up, the take-up reel  74  will be activated to reel up the excess hose  32  until the assembly reaches its end position. The image device may be a camera, but it should be appreciated to those skilled in the art that it could also be a sensor or the like. 
         [0038]      FIG. 1A  shows a small section of the curable material  28  applied to the wall  12  of the pipe  10 . The instantaneous compression of the curable material  28  by the bladder  44  has many advantages. It prevents the material from sagging and running toward the bottom of the pipe  10 . The compression also presses the material into fractures in the pipe  10  which stops water infiltration until the material is able to cure. Additionally, the bladder  44  ensures that the material cures into an even layer, and cures with a smooth finish for more stability and to make sure that the material has not created any blockages. The bladder is sized to create a layer of material having a predetermined thickness as well. For example, one size of pipe that may be repaired may be eight inches in diameter. A material thickness of one-quarter of an inch may be determined to be enough to fully repair the structure of the pipe. Therefore, a bladder having an inflated diameter substantially equal to seven and one-half inches would be selected to produce this thickness. Because the bladder is inflated almost instantaneously as the material is applied to the pipe wall, the material will still be viscous enough to be pressed evenly about the outer surface of the bladder to produce an even layer of material about the interior of the pipe. 
         [0039]      FIG. 1B  shows the liner assembly  30  after the bladder  44  and the dispensing unit  34  have moved along a portion of the pipe  10 . The service connections to the lateral pipes  18  must be later reinstated using a robotic cutter or the like. Using a bladder  44  having a reinforced scrim, as previously described, limits the expansion of the bladder  44  when otherwise unconstrained at the lateral service connections. Once the desired length of lining has been applied to the pipe  10 , the bladder  44  can stop inverting, but the pressure in the bladder  44  is maintained until the curable material  28  has fully cured and hardened. It should be appreciated by those in the art that using a material as described above will shorten the length of cure time due to the characteristics of the material. The shorter cure time will shorten the repair time and increase productivity. 
         [0040]    In a preferred form of the invention, the bladder  44  is removed after the curable material  28  has cured and hardened. The bladder  44  is removed by pulling the rope  72 , which reinverts the bladder  44 . The easy removal of the bladder  44  is facilitated by the use of a non-stick bladder, as previously described. The dispensing unit  34  is also removed from the pipe  10  through the downstream manhole  14  and all of the dispensing hose  32  is reeled into the take-up reel  74 . 
         [0041]      FIG. 4  shows an alternative embodiment of the preferred lining method using a bladder  86  that is not removed from the pipe  10 . In this embodiment, the exterior surface  54  of the bladder  86  is uneven or irregular in shape, which facilitates a mechanical bond between the cured material  78  and the bladder  86 .  FIG. 4  shows a section of the finished lining with the cured material  78  and the bladder  86 . The bladder  86  has become mechanically bonded to the cured material  78  by use of various protrusions  56  located on the exterior surface  54  of the bladder  86 . 
         [0042]    The enlarged sectional views in  FIGS. 5A-5C  show the exterior surface  54  of the bladder  86  including various projections  56  which can be used to physically trap the cured material  78 . The hook-like projections or protrusions  56  trap the material to create a mechanical bond between the curable material and the bladder  86 . The bladder  86  creates a smooth, impermeable coating for the pipe  10 , which further strengthens the wall and also creates a new layer of protection against the infiltration of water into the pipe  10 . Once the material has cured and hardened, a closed end  48  of the bladder  86  can be cut out to reinstate service through the pipe  10 . The bladder  86  will also be cut at an open end  58  at a location near the end of the section of pipe being repaired. 
         [0043]    The invention has been shown and described above with reference to preferred embodiments, and it is understood that modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. The invention is only to be limited by claims appended hereto.

Technology Classification (CPC): 8