Patent Document

TECHNICAL FIELD 
     The invention related to an apparatus and method for removing obstructions from, stripping lining from and rerounding damaged or collapsed underground pipes. 
     BACKGROUND OF THE INVENTION 
     Underground pipelines used to convey water, gas, sewage and other fluids have, in the past been constructed of clay tile, concrete, cast iron, ductile iron, steel or even wood. These pipelines have limited useful service lives due to deterioration of mechanical properties leading to leakage, collapse, ingress of external matter (soil), or blockages due to, foreign matter buildup as a result of internal discontinuities. In some cases, deterioration of mechanical properties may be due to chemical attack. For example, concrete pipe and cast iron and/or ductile iron pipe is susceptible to interior degradation, particularly at the “crown” of the pipe, due to the effect of hydrogen sulfide gas. In other cases mechanical or environmental factors may cause the deterioration. For example, tree roots may accelerate or cause degradation or blockages of underground lines. Deterioration may occur throughout the body of the pipe or at the connections between pipe segments. 
     Pipe lining is a process that was developed to enhance or prolong the useful life of pipelines, in particular, underground lines. The lining is typically installed in-situ in cases wherein the mechanical and physical properties of the pipe have degraded, but before total collapse. In some cases, the lining is installed when the pipe is new during the manufacturing process with the intention of providing a barrier between the conveyed product and the host pipe material. These linings provided enhanced performance and service life. However, just as the host pipes had a limited life span, typically measured in decades, so did many of the early lining systems. Many linings that slowed or stopped deterioration of the host pipes are now suffering from the same ills that plagued the original host pipes. In some cases blockages due to lining collapse have resulted where the bond between the lining and host pipe has failed or where foreign material has entered between the lining and host pipe. 
     Failure of a pipe lining presents a dilemma to the owners of pipe systems that have previously been lined using early technology lining systems. In most instances, the failing lining prevents the use of new lining technologies to repair the existing host pipe, leaving the owners with two options. The lined pipe may be burst (see Streatfield et al., U.S. Pat. No. 4,738,565) and a new pipe pulled in, with some added difficulty due to the lining. Alternatively, the entire length of the pipe may be excavated to remove and replace the existing pipe. However, the host pipe holds value in that it could possibly be lined by utilizing one of the new and improved technologies. 
     The use of mechanical devices to clean and maintain pipes has been limited to the removal of relatively loose debris and damaged lining. For example, a mechanical rotary device for removing old pipe linings is disclosed in Wentworth et al. Ser. No. 11/324,018, filed Dec. 30, 2005. However, often a ductile pipe will partially collapse or become twisted, and needs to be restored to a round profile before lining can be attempted. See also Harr U.S. Patent Publication 20050097689, May 12, 2005, which describes a tool for cleaning a culvert including a bucket attachment to a rod string for pushing or pulling debris out of the culvert. A need remains for a process and apparatus suitable for clearing solid obstructions, removing linings or liners from and repairing damaged or twisted pipelines, and provide of restoring the shape of pipelines that have been distorted. This overall maintenance would prolong the life well being of such pipelines. The present invention addresses this need. 
     SUMMARY OF THE INVENTION 
     A method for reforming an underground pipe according to the invention includes the initial steps of inserting a reforming tool into the underground pipe and locating the pipe reforming tool at a location to be reformed. At least two arms of the reforming tool are then extended into engagement with the inner periphery of the underground pipe, which arms push the underground pipe outwardly in a manner effective to change its cross-sectional shape. The arms may then be retracted and the tool withdrawn from the pipeline. Such “reforming” or “rerounding” tool is preferably mounted at the distal end of a rod string so that the tool can be pushed, pulled and/or spun by operation of the rod pulling and pushing machine powering the rod string. “Rerounding” for purposes of the invention means restoring the interior of the pipeline at the target location to a more cylindrical profile. Following rerounding or reforming, the pipeline will most likely be relined as discussed further below. 
     In a preferred form of the invention, the arms of the reforming tool are collapsible and connected to a hydraulic cylinder, such that the extending and retracting steps are carried out by activating or actuating the hydraulic cylinder. The hydraulic cylinder can operate using hydraulic fluid such as water supplied through the rod string. A double-acting cylinder may be used, but preferably a spring biases the hydraulic cylinder to a collapsed position in which the arms are retracted, and pressure from the hydraulic fluid supplied through the rod string overcomes the force of the spring when the arms are extended. Fluid in the hydraulic cylinder flows through an exhaust port into the pipeline when the spring biases the hydraulic cylinder to a collapsed position. 
     A collapsible rotary apparatus for reforming an underground pipeline according to the invention includes a tubular housing including a rear connector configured for connection to a drill string, and a hydraulic cylinder including a cylinder body and an extendable piston. At least two collapsible arms are mounted on the tubular housing in positions to exert forces in opposing directions on a pipeline interior when the arms are extended. Linkages connect each of the arms to the hydraulic cylinder so that the arms are extended in response to activation of the hydraulic cylinder. Suitable means for returning the arms to a collapsed position following activation of the hydraulic cylinder is provided, as by using a spring or double acting cylinder as mentioned above. These and other aspects of the invention are discussed in the detailed description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will hereafter be described with reference to the accompanying drawings, wherein like numerals denote like elements, and wherein: 
         FIG. 1  a perspective side view of an apparatus according to the invention including a pipe rerounding tools attached to the collapsible arms, wherein the arms of the device are illustrated in an extended or deployed position; 
         FIG. 2  is a lengthwise section of the cylindrical housing of the apparatus shown in  FIG. 1 ; 
         FIG. 3  is a lengthwise section of the cylindrical housing of the apparatus shown in  FIG. 2 , in a collapsed or at rest position; 
         FIG. 4  is a side view of the apparatus shown in  FIG. 1 ; 
         FIG. 5  is a side view of the apparatus shown in  FIG. 1  in a collapsed position; 
         FIG. 6  is a front view of the apparatus of  FIG. 1 ; 
         FIG. 7  is a rear view of the apparatus of  FIG. 1 ; 
         FIG. 8  is a partial side view of a piston and head nut assembly of the apparatus of  FIG. 1 ; 
         FIG. 9  is a side view of the cylinder body of the apparatus of  FIG. 1 ; 
         FIG. 10  is a side view of the apparatus of  FIG. 1 , wherein the pipe rerounding tool has been replaced with a lining stripping tool; 
         FIG. 11  a rear view of the apparatus of  FIG. 10 ; 
         FIG. 12A  is a partial perspective view of a roller assembly attachment system according to the invention; 
         FIG. 12B  is a partial perspective view of a roller assembly attachment system of  FIG. 12A , showing the opposite side; 
         FIG. 13A  is a partial perspective view of a further roller assembly attachment system according to the invention; 
         FIG. 13B  is an exploded view of portions of the attachment system shown in  FIG. 13A ; 
         FIG. 14  is a side view of the apparatus of  FIG. 1 , wherein the pipe rerounding tool has been removed and a set of grappling claws which are in a closed position have been installed; 
         FIG. 15  is a side view of the apparatus of  FIG. 14 , with the grappling claws in an open position; 
         FIG. 16  is a side perspective view of the apparatus of  FIG. 14 ; 
         FIG. 17  is a rear view of the apparatus of  FIG. 12 ; 
         FIG. 18  is a rear view of an apparatus according to the invention disposed in a deformed ductile pipeline; 
         FIG. 19  is a rear view of an apparatus according to the invention disposed in a ductile pipeline following a rerounding operation according to the invention; and 
         FIG. 20  is a front view of an apparatus of the invention with a set of digging blades installed, shown in a closed position. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a reforming apparatus  10  according to the invention is designed for use with a horizontal directional drilling (HDD) machine such as the Vermeer Navigator or a rod pushing machine that is incapable of spinning the rod string. Apparatus  10  includes a tubular housing  11  having a threaded recess-type connector  12  at its rear end suitable for connection to the distal end of a drill string which may include an adapter  14  and starter rod  15  mounted on the distal end of a string of hollow rods. Connector  12  shown is a Splinelok® connection of the type described in Wentworth et. al. U.S. Pat. No. 6,148,935, Nov. 21, 2000, the contents of which are incorporated by reference herein. However, an API threaded socket can be used for direction connection to the threaded leading end of the drill string. 
     Housing  11  at its leading end includes the body portion of a hydraulic cylinder  13 . As shown in  FIGS. 3 to 9 , cylinder  13  includes a tubular cylinder body  16  slidably disposed inside of an outer sleeve (runner)  17 , and a piston  18  disposed for reciprocation inside of cylinder body  16 . Piston  18  has a rear head  19  that is in sliding contact with the inner surface of body  16 . Contact between head  19  and cylinder body  16  is close but not sealed, so that fluid inside of the pressure chamber  21  can leak out at a controlled rate. For this purpose, a lengthwise relief groove  22  can be provided along the outside of head  19  (see  FIG. 8 ). 
     The front end of piston  18  extends through a central hole in a head nut  23  threadedly secured in the front end of open end of cylinder body  16 . Engagement between piston  18  and nut  23  may be sealed, or permit a small amount of pressure fluid leakage out of the front of the unit. One or more spacer nuts  25  are threaded onto the exposed front end of piston  18  and can be adjusted to stop the piston from moving further back than the position at which rearwardmost nut  25  engages the bottom of a front recess  26  in head nut  23 . 
     The front end of a plunger  27  is engaged in a rearwardly opening recess  28  in piston  18  by means of a split ring  29  that fits in an annular groove  30  in the wall of recess  28 . A rear end portion of plunger  27  is slidably mounted in a guide sleeve  31  that forms part of housing  11  and may be welded or otherwise secured to the back of cylinder body  16 . Plunger  27  has a rearwardly extending central boss  32  at its rear end. A compression spring  33  is inserted into guide sleeve  31  with its front end wound over boss  32 . The rear end of spring  33  is disposed inside connector  12  and held by any suitable means, such as a front end face of adapter  14 . To complete housing  11 , connector  12  is welded or otherwise secured to the back of guide sleeve  31 . 
     Piston  18  and its extension (plunger  27 ) are mechanically engaged with outer sleeve  17  by means of a first transverse through hole  36 A in plunger  27  which is in alignment with a pair of threaded holes  37 A in sleeve  31 , and a pin  38  removably mounted in holes  36 A,  37 A. Pin  38  passes through a pair of grooves  39 A on opposite sides of cylinder body  16 . Grooves  39 A are elongated in the lengthwise direction of apparatus  10  so that cylinder body  16  can slide relative to piston  18 , plunger  27  and sleeve  17  over a range equal to the length of grooves  39 A. A second pair of holes  36 B,  37 B and second pair of grooves  39 B are provided at positions rearwardly offset from  36 A,  37 A,  39 B and offset by 90° radially. In this manner, pin  38  can be moved from holes  36 A,  37 A to  36 B,  37 B in order to change the stroke of the unit as explained hereafter. 
     At least two (in this example, three) arm assemblies  50  extend and retract in response to movement of piston  18 . Each arm assembly includes a pair of front and rear beams  51 ,  52  connected by a middle pivot  53 . Front beams  51  are connected to a front end portion of cylinder body  16  by a linkage including pivots  54  mounted in sets of brackets  56  on the outside of cylinder body  16 . In a similar fashion, the rear ends of rear beams  52  are connected to outer sleeve  17  by linkages comprising pivots  57  mounted in sets of brackets  58  on the outside of sleeve  17 . Brackets  56 ,  58  are aligned with each other in each arm assembly  50  and are positioned so that arm assemblies  50  will be spaced equiangularly, 120° apart in this example, which is sufficient to exert forces in opposing directions on the pipeline interior. Front and rear, beams  51 ,  52  are U-shaped in cross section with rear beams of slightly less width such that the front end of each beam  52  fits inside the rear end of a beam  51  as shown. Each pivot  53  passes through a pair of holes in each side of beams  51 ,  52 . Front beams  51  are longer than rear beams  52 , and with the arm assembly in a collapsed position as shown in  FIG. 5 , pivots  53  are positioned outwardly and far to the rear of rear pivots  57 . 
     Holes provided in the outside of the rear end of each front beam  51  permit a variety of removable attachments to be mounted in a position to engage the inside of a pipeline. In  FIGS. 1-9 , a roller assembly  60  is mounted to each front beam  51  by any suitable means, such as welding or bolts set in holes in a base plate  62  of the assembly  60  and corresponding holes in front arm beam  51 . A pair of end brackets  63  rotatably support a cylindrical roller  64 . Rollers  64  are positioned for tangential rolling contact with the inside of a pipeline in a manner suitable for a rerounding operation. 
     Such an operation may be carried out as follows. Apparatus  10  is mounted at the distal end of a string of drill rods powered by an HDD machine using adapter  14  and starter rod  15 . Additional rods are added as apparatus  10  in a collapsed state is advanced to a location in the pipeline in need of reforming or re-rounding. Once at the desired location, pressure fluid such as water is fed through the center of the rod string and enters a central channel in starter rod  15 . Further flow of water through adapter  14  is blocked such as by plugging one end of the central bore normally provided. Instead water flows through a radial hole  71  in the wall of starter rod  15 . A hose  72  provided with end fittings feeds water through a port  73  through the wall of cylinder body  16 . The pressure, taking into account leakage, is great enough to compress spring  33  and cause piston  18  and plunger  27  to move rearwardly relative to housing  11 . The front end of piston  18  pulls part way inside of cylinder body  16  as shown in  FIGS. 2 and 4 . Sleeve  17  moves with piston  18  and plunger  27  since it is connected to plunger  27  by pin  38 , but travel is limited by the rear ends of the associated grooves  39 A or  39 B. The stroke of the cylinder thus cannot exceed the length of grooves  39 A,  39 B. 
     As piston  18  moves rearwardly and the distance between front and rear pivots  54  and  57  increases, the arm assemblies  50  unfold outwardly by pivoting about middle pivots  53 , moving from the position shown in  FIG. 5  to the position shown in  FIG. 4 . Rollers  64  move to engage the inner periphery of the pipeline, and the force applied by means of arm assemblies  50  or the outside of the rear end of each front beam  51  (if no rollers are provided) is great enough to force a ductile pipe wall outwardly. As illustrated in  FIGS. 18 and 19 , during or after such a pushing operation, the operator may rotate the drill string so that apparatus  10  both spins and pushes outwardly at the same time in a manner to restore the interior of the pipeline at the target location to a round profile. 
     Once the rerounding operation is done, the supply of pressurized water to chamber  21  is cut off. Water continues to leak out the front and/or rear ends of chamber  21 . Water escaping through the rear end of piston  18  can exit housing  11  through grooves  39 A,  39 B. Spring  33  expands to push the water out of chamber  21  and move piston  18  back to its extended position. This in turn reverses the previous movement of arm assemblies  50 , causing them to return to the collapsed position. At this stage, the apparatus  10  can then be withdrawn from the pipeline or else moves to another location in need of reforming at which the foregoing steps are repeated. 
     As shown in  FIGS. 10-11 , rollers  64  can be replaced with stacked cutter wheels  81  provided with teeth or serrations  82  for stripping a liner from the inside of the pipeline at the same time as, or instead of, reforming it. Apparatus  10  can thereby be used for multiple purposes depending on the situation. 
     According to a further aspect of the invention, roller assemblies  60  using either roller  64  or stripper wheels  81  can be mounted in different positions, and can be installed and removed interchangeably.  FIGS. 12A and 12B  illustrate an arrangement for mounting of wheels  81  on the sides of front beams  51 . A large central hole  41  is provided through base plate  62  together with a series of spaced smaller holes  42  positioned to one side of it. A hat bushing  43  is set in hole  41 so that its flange engages the outer surface of base plate  62  just below wheels  81 . A bolt acting as pivot  53  is countersunk into bushing  43  and secured at its other end by a nut  44 , thereby rotatably mounting roller assembly  60  to arm beam  51 . Pivot  53  passes through a pair of bearing sleeves  45  welded into aligned, nearly circular openings in the sides of arm beam  51 . Arm  52  is mounted on pivot  53  between bearing sleeves  45 . 
     So secured, the roller assembly can pivot to conform to the inside profile of the pipeline  90 . To limit pivoting of roller assembly  60  so that it does not spin about pivot  53 , two or more roll pins  46  are set into smaller holes  42  and extend from the underside of plate  62 . Roll pins  46  engage the side of arm beam  51  to prevent roller assembly  60  from pivoting too far in either direction. To remove the roller assembly  60 , roller  64  or wheels  81  are first removed from brackets  63 , and then pivot  53  is removed so that hat bushing  43  and roller assembly  60  can be pulled off of arm beam  51 . The bolt used as pivot  53  can then be replaced or substituted with a shorter bolt set in its place. Roller assembly  60  can then be refitted and replaced. 
       FIGS. 13A and 13B  shows a roller assembly  60  moved to a position on the top or outside of beam  51 , rather than on its side. In this embodiment, a boss  47  is welded to the outside of each arm  51  near pivot  53 . Plate  62  is positioned over boss  47  so that hole  41  is in alignment with it. Hat bushing  43  is inserted through hole  41  and is secured to boss  47  with a tap screw  48 . Screw  48  engages a threaded central hole  49  in boss  47 . Base plate  62  and hat bushing  43  are interchangeable for use in either of the side mount and top mount embodiments. Additional spacers similar to bushing  43  in shape can be stacked on bushing  43 , and a longer screw  48  can be used to vary the distance that roller assembly  60  is spaced from arm beam  51 . This may vary depending on the size of the pipeline  90  and the maximum size the device is capable of opening to when the arms are fully extended. 
     Occasionally a pipe cleaning and reforming operation is halted by a large obstruction such as a stone or piece of wood or concrete that is blocking the collapsed pipeline. In a further adaptation of the apparatus  10  according to the invention shown in  FIGS. 12-15 , roller assemblies  60  are removed to reduce the external diameter of the device when the arms are unfolded, and a set of three gripping jaws  86  are mounted on front beams  51 . Each jaw  86  has a front, inwardly curving or hook-shaped tip portion  87  and a rear shank  88 . Shank  88  of each jaw  86  extends through lengthwise openings  89  in the outer wall of beam  51 . Shank  88  has a pair of holes therein by which it can be mounted on two pins  91  each set through a pair of holes  92  in the sides of front beam  51  at spaced positions as shown. By this means jaws  86  move in tandem with arm beams  51  and can be opened and closed, or moved to a partially closed position, as needed to grasp an object in the pipeline. Once the object us held by jaws  86 , the drill string is withdrawn so that the object is brought out of the pipeline. This provides an alternative to attempting to push/or pull the object as described in the Harr patent publication cited above. 
     As the foregoing description shows, the apparatus of the invention can be used for multiple purposes by changing the attachments provided on the front arm beams. As the need arises during a job of pipe cleaning or stripping, the apparatus can be used to strip a liner, reshape a section of the pipeline that has become distorted, or even pull debris out of the pipeline in situations where the bucket attachment provided in the in the Harr patent publication cited above proves ineffective. For the latter purpose, jaws  86  can be replaced with other accessories such as a set of rounded shovel blades  91  (see  FIG. 20 ) so that the apparatus can be used to excavate soil from a pipeline in a manner similar to a post-hole digger. 
     The method and apparatus of the invention will most often be used in connection with a pipe relining operation. In most cases, after the line has been cleared, a replacement pipe such as one made of polyethylene will be pulled into the existing pipeline, or one of a number of known relining processes will be used wherein a lining is formed on the inside of the existing pipeline. As part of the method of the invention, a step of relining the pipeline may follow the steps discussed above. This step may be carried out after or during the steps of the pipe cleaning method. A replacement pipe may be pulled into the pipeline by attaching it to the front of apparatus  10  at jaws  86 , which are connected by a cable to swivel bearing joint, shackle and pipe puller such as shown in Wentworth et al. U.S. Pat. No. 7,086,808, the contents of which are incorporated by reference herein. Additional holes to provide connector eyes may be formed as needed in the tips of jaws  86 . As apparatus  10  is pulled by the drill string from one end of the pipeline to the other, pausing where necessary to reform or expand the existing pipeline, the replacement pipe advances into the pipeline in front of it. 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments will be apparent to persons skilled in the art upon reference to the description. Such variations and additions are specifically contemplated to be with the scope of the invention. It is intended that the appended claims encompass any such modifications or embodiments.

Technology Category: f