Abstract:
A method and apparatus for installing a flexible lining tube in an underground pipe by eversion. A pressure vessel is equipped with a gasket that has an arcuate slot for receiving the lining tube in a manner that provides an effective seal without creating undue friction. A guide has a cylindrical wall curved in conformity with the slot and a conical surface leading to the cylindrical wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       FIELD OF THE INVENTION 
       [0002]    This invention relates in general to the rehabilitation of underground pipes and deals more particularly with the installation of a flexible lining tube into an underground pipe by everting the lining tube using fluid pressure. 
       BACKGROUND OF THE INVENTION 
       [0003]    Subterranean pipes and conduits such as sewers have been repaired and/or rehabilitated using a number of techniques. One approach that avoids the need for excavation is a process that involves everting a resin impregnated lining tube into the underground pipe using fluid pressure, expanding the tube with fluid pressure, and then curing the tube in place against the interior surface of the sewer pipe. Although this technique has been used for a number of years and has worked well for the most part, it has not been wholly free of problems. 
         [0004]    For example, when everting the lining tube into the sewer pipe, significant friction forces must be overcome. As exemplified by U.S. Pat. No. 6,390,795 to Waring et al., the lining tube is typically flattened and extended through a linear slot. The slot must provide a seal that is tight enough to maintain adequate pressure for everting the tube, while the seal must not be so tight that the frictional forces are unduly high. Using a linear slot such as in the Waring patent has proven to be problematic because the seal applies so much friction that there is an excessive restraint on pulling of the liner into the sewer pipe. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present invention, an improved method and apparatus is provided for installing flexible lining tubes into underground pipes such as sewers. A pressure vessel is equipped with a gasket in which an arcuate slot is formed. The lining tube is collapsed with its walls overlaid in a double-ply configuration and arranged in a curve to conform with the shape of the arcuate slot. This allows the lining tube to be extended through the slot, preferably with guidance from a forming member having a wall that is curved generally in conformity with the curvature of the arcuate slot. The leading end of the lining tube is coupled with the downstream end of the pressure vessel in a substantially fluid tight manner. Fluid pressure applied to the pressure vessel propels the lining tube out of the vessel and into the pipe as the tube is everted and continuously pulled through the slot until the entirety of the tube has been installed in the underground pipe. 
         [0006]    The curved configuration of the slot is a significant feature of the invention. The smooth curvature results in reduced friction to facilitate passage of the lining tube through the slot while reducing the power that is needed for eversion. At the same time, the slot can be custom cut to a size that effects a sufficient seal with the lining tube allowing eversion to proceed without large losses of pressure containment. The construction of the equipment preferably allows different gaskets to be interchanged so that different sizes of lining tubes can be accommodated without the need for wholly different equipment for each size. 
         [0007]    Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0008]    In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like or similar parts in the various views: 
           [0009]      FIG. 1  is a perspective view of an apparatus for installing flexible lining tubes in underground pipe in accordance with a preferred embodiment of the present invention; 
           [0010]      FIG. 2  is a perspective view of eversion apparatus that may be used in accordance with the invention; 
           [0011]      FIG. 3  is an exploded perspective view of the apparatus shown in  FIG. 2 ; and 
           [0012]      FIG. 4  is a perspective view of the eversion apparatus with a flexible lining tube that is to be installed depicted in broken lines. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Referring now to the drawings in more detail and initially to  FIG. 1 , numeral  10  generally designates a stand which may be used for the mounting of a flexible lining tube installation device constructed according to the present invention. The stand  10  includes opposing pairs of legs  12 . Each pair of legs is arranged generally in the configuration of the letter A to provide an A-frame structure when the stand  10  is erected. A roller  14  is supported for rotation at the top ends of the A-frames provided by legs  12 . The axis about which roller  14  turns is preferably a generally horizontal axis. The stand  10  may be arranged to collapse for ease of storage and transport. 
         [0014]    In use of the equipment, the stand  10  is erected on a horizontal support surface that overlies a manhole or other access to the underground pipe which is to be rehabilitated in accordance with the invention. The stand  10  may provide support for an eversion device which is generally identified by numeral  16 . As shown additionally in  FIGS. 2 and 3 , the eversion device  16  provides a pressure vessel which includes a funnel shape body  18  connected at its lower end with a cylindrical tube  20 . Opposite sides of the body  18  are provided with co-axial shafts  22  having their connections with body  18  reinforced by gusset plates  23 . The shafts  22  may be supported at their outer ends on brackets  24  ( FIG. 1 ) which are secured to the legs  12  of stand  10 . The brackets  24  provide a number of pockets  26  in which the ends of the shaft  22  are received, with the pockets  26  varying in their elevation to allow variation in the elevation of the eversion device  16 . When shafts  22  are applied to the brackets  24 , the shafts provide a horizontal axis about which the eversion device  16  may pivot on the stand  10 . 
         [0015]    With reference to  FIG. 3  in particular, the upper end of body  18  is covered by a circular plate  28  which may be welded or otherwise suitably secured to the upper edge of body  18 . An arcuate slot  30  is fanned through plate  28  with its center of curvature coincident with the center of plate  28 . The slot  30  separates plate  28  into a peripheral ring  32  and a circular center  34  which are connected by a neck  36  located between the opposite ends of the arcuate slot  30 . An angled brace  38  located within body  18  is connected at its upper end with the center of plate  28  and at its lower end with the interior wall of body  18  to provide support for the center portion  34  of plate  28 . The brace  28  extends beneath the neck  36  to avoid obstructing the area beneath slot  30 . 
         [0016]    With continued reference to  FIG. 3 , a circular gasket  40  overlies plate  28 . The gasket  40  may be constructed of any material suitable to provide a seal with the lining tube that is installed by the eversion device  16 . For example, the gasket  40  may be constructed of a reinforced silicon material. As will be explained, prior to use, an arcuate slot  41  (see  FIGS. 2 and 4 ) is cut through the gasket  40 . While an arcuate slot is preferred, other curved slot configurations may be used as well. 
         [0017]    Optional shims  42  and  44  ( FIG. 3 ) may be utilized in the eversion device  16 . Shim  42  may be in the form of a circular disk having a smaller diameter than the gasket  40 . Shim  44  may take the form of an annular ring having an outer diameter substantially equal to that of gasket  40 . The inside diameter of shim  44  is greater than the outside diameter of shim  42  to provide a continuous annular opening  46  between the shims  42  and  44 . The opening  46  is located and shaped to register with the slot  41  that is cut in gasket  40  when the shims  42  and  44  are applied on top of gasket  40 . 
         [0018]    A face plate  48  overlies gasket  40  (and shims  42  and  44  when they are used) and may have the same construction as plate  28 , including an arcuate slot  50  which is identical in size and shape to slot  30 . When the equipment is assembled, the gasket  40  is sandwiched between plates  28  and  48 , with the shims  42  and  44  optionally being sandwiched between the gasket  40  and face plate  48 . 
         [0019]    A guide  52  is mounted on top of the face plate  48  and acts to provide assistance in guiding of the flexible lining tube in a manner to be explained in more detail. The guide  52  has on its lower portion a cylindrical wall  54  having a lesser diameter than that of the inside edge of slot  50 . The top portion of guide  52  takes the form of a frusto-conical surface  56  which tapers upwardly from the upper edge of the wall  54 . The guide  52  may be secured in place by a bolt  58  equipped with a tee handle  60  to facilitate tightening and loosening of the bolt  58 . 
         [0020]    In setting up device  16  for use, the gasket  40  is provided with the arcuate slot  41  that is cut with a curvature to conform with the curvature of slots  30  and  50  and a width and length to accommodate the flexible lining tube that is to be installed. As shown in  FIG. 4 , the lining tube  62  is initially arranged in a collapsed condition with its walls  64  and  66  overlaid on one another in a double ply configuration. The slot  41  which is formed in gasket  40  may be cut in any desirable manner. However, it is important for the width of the groove to be sufficient to allow tube  62  to be pulled through the slot  41  without excessive friction that may provide an undue restraint to the process. Conversely, the slot  41  should not be so large that it provides an ineffective seal with the tube  62  such that inadequate pressure for eversion is maintained within the eversion device  16 . 
         [0021]    After the arcuate slot  41  has been cut in gasket  40  in the appropriate size and shape for the particular lining tube that is being handled, the gasket  40  is applied to plate  28  with slot  41  aligned with slot  30 . The face plate  48  is then applied on top of the gasket  40 , optionally with the shims  42  and  44  interposed between the gasket  40  and the face plate  48 . The face plate  48  is installed with its slot  50  in alignment with slot  41 . The shims  42  and  44  are preferably installed when relatively thin tubes  62  are to be handled by the equipment. Screws  68  (see  FIG. 3 ) or other fasteners may be applied through preformed holes in the face plate  48 , shims  42  and  44  and gasket  40  and threaded into holes in the plate  28  to secure the upper assembly on top of body  18 . Guide  52  is then secured on top of the face plate  48  by extending the bolt  58  through center holes in the face plate  48 , shim  42  and gasket  40  and threading the bolt  58  into an opening  70  formed in the center of plate  28 . 
         [0022]    The tube  62  is arranged for installation and is impregnated with resin in a manner well known in the industry. Tube  62  is initially arranged in its collapsed condition with its walls  64  and  66  overlaid on one another and the leading end of the tube  62  arranged in a curve conforming with the curvature of slot  41 . The leading end of tube  62  is extended through slot  41  and through the eversion device  16 . As shown in  FIG. 4 , an end can  72  may be releasably secured to the bottom of tube  20  so that the end of tube  62  can be extended through the end can  72  and arranged in a cuff  74  ( FIG. 4 ). The cuff  74  may be turned upwardly on the lower end portion of the end can  72  and secured by a band  76  or other securing means. 
         [0023]    Fluid pressure may then be applied to the interior of the eversion device  16  through a hose coupling  78  in order to pressurize the inside of the pressure vessel. The fluid is typically air but may be any suitable fluid. The fluid pressure pushes the tube  62  out through the bottom of the end can  72  while everting the tube  62  and pulling it continually through the slot  41 . As the tube  62  is everted and extended out through the bottom of the end can  72 , it is extended through a manhole (not shown) into an underground sewer pipe. Once the bottom of the manhole has been reached, the eversion device  16  may be moved downwardly on stand  10  into one of the lower pockets  26  in order to provide slack in tube  62  so that the tube can be turned generally horizontally into the sewer pipe. 
         [0024]    The fluid pressure is then applied again to the pressure vessel to complete installation of the tube  62  through the desired length of the sewer pipe. The pressure may then be relieved, and the eversion device  16  may be detached from the end can  72  prior to subsequent addition of heat and pressure to the tube  62  in accordance with conventional practice to expand tube  62  against the interior wall of the sewer pipe and cure it in place. 
         [0025]    Due to the curved shape of slot  41 , the friction encountered when pulling tube  62  through slot  41  is reduced without significant pressure loss within the pressure vessel. The tube  62  is guided into the slot due to the cylindrical shape of wall  54  and the conical shape of surface  56  as the tube  62  feeds into slot  41 . 
         [0026]    From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. 
         [0027]    It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
         [0028]    Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.