Abstract:
A tool for separating a gasketed pipe joint includes a body comprising a relatively thin member formed into a partially cylindrical shape having spaced-apart forward and rear edges; and an arcuate reinforcing collar attached to an outer surface of the body adjacent the rear edge. A driving apparatus for the tool includes a first driving ring adapted to be mounted around one of the pipes and sized to bear against the gasket release tool; a second driving ring adapted to be mounted around the other one of the pipes and sized to bear against the socket; and apparatus for drawing the first and second driving rings together so as to drive the gasket release tool into a pipe joint.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of Provisional Application No. 60/557,570 Filed Mar. 30, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates generally to joints for ductile iron pressure pipe and more particularly to a tool for disconnecting ductile iron pipes which have been joined with toothed gaskets.  
         [0003]     In many applications where pipes are joined in telescoping relationship, for example water and sewer pipes, the smooth or spigot end of one pipe is inserted into the socket end of the engaging pipe. The socket end has an opening large enough to receive the spigot end of the enclosed pipe. A gasket is inserted in the socket end of the enclosing pipe and prevents leakage of fluid from the joint by forming a seal between the two pipes. In applications where the fluid such as water for fire mains or municipal water distribution is under high pressure, various means are used to prevent separation of the two pipes. Although pipes may be connected with bolted flanges, blocks or other external restraining devices to prevent separation, these methods are costly and time consuming.  
         [0004]     Another known method to prevent separation of the pipes is to use a rubber gasket which serves as a fluid seal and which also has toothed metal segments spaced uniformly around its inner perimeter. The metal segments pivot about a bead to allow the spigot end of one pipe to be inserted into the socket end of the other pipe while preventing withdrawal of the inserted pipe under high fluid pressure conditions. The toothed metal segments bite into the outer surface of the spigot of the inserted pipe and prevent withdrawal of the inserted pipe. Such gaskets are described in U.S. Pat. No. 5,295,697 assigned to U.S Pipe &amp; Foundry Company, Birmingham, Ala., USA 35222, and available under the name FIELD LOK from the same company.  
         [0005]     The significant holding power of this type of gasket represents a drawback when a pipe joint must be taken apart. In order to disconnect pipes joined with one of these gaskets, it is first necessary to release all of the individual toothed metal segments. If a single one of the segments is not released, it will be impossible to separate the pipes, even with heavy construction equipment. In the prior art, the pipes have been separated using an array of narrow shim-type tools which are driven into the pipe joint to release each individual segment. However, such tools are prone to breakage and are tedious to use because the exact location of each toothed segment around the periphery of the pipe joint is not known. If all of the teeth cannot be released, the pipes must then be separated by cutting. This requires subsequent patching or replacement with new pipes, which is wasteful and time consuming.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     Accordingly, it is an object of the invention to provide a tool for simultaneously releasing all of the toothed segments of a pipe gasket.  
         [0007]     It is another object of the invention to provide a method for simultaneously releasing all of the toothed segments of a pipe gasket.  
         [0008]     It is another object of the invention to provide an apparatus for driving a release tool without impact tools.  
         [0009]     These and other objects are met by the present invention, which according to one embodiment provides: a tool for separating a gasketed pipe joint, including: a body comprising a relatively thin member formed into a partially cylindrical shape having spaced-apart forward and rear edges; and an arcuate reinforcing collar attached to an outer surface of the body adjacent the rear edge.  
         [0010]     According to another embodiment of the invention, a chamfer is formed on the forward edge  
         [0011]     According to another embodiment of the invention, the body and the reinforcing collar are made from stainless steel.  
         [0012]     According to another embodiment of the invention, the body has a thickness of about 16 gage.  
         [0013]     According to another embodiment of the invention, the reinforcing collar has a thickness of about 0.5 inches  
         [0014]     According to another embodiment of the invention, at least one weld bead is disposed on a rear face of the reinforcing collar to harden the face and reduce deformation of the reinforcing collar under impact.  
         [0015]     According to another embodiment of the invention, the body extends through an angle of approximately 180 degrees in a circumferential direction  
         [0016]     According to another embodiment of the invention, the body extends through an angle of approximately 120 degrees in a circumferential direction.  
         [0017]     According to another embodiment of the invention, the body extends through an angle of approximately 90 degrees in a circumferential direction.  
         [0018]     According to another embodiment of the invention, a method is provided for separating a pipe joint of the type including a first pipe received inside a second pipe and restrained therein by a resilient gasket carrying an annular array of toothed rigid segments which engage an outer surface of the first pipe to prevent withdrawal thereof. The method includes: providing at least one gasket release tool having a body formed into an arcuate shape and adapted to be received between the first and second pipes; placing one or more of the gasket release tools along an outer surface of the first pipe, such that the gasket release tools collectively engage all of the rigid segments; and driving the gasket release tools to into the joint so as to disengage the rigid segments from the first pipe.  
         [0019]     According to another embodiment of the invention, each of the gasket release tools includes an arcuate reinforcing collar attached to an outer surface of the body adjacent a rear edge thereof.  
         [0020]     According to another embodiment of the invention, each of the gasket release tools are extends through an angle in a circumferential direction such that two of the tools engage all of the rigid segments.  
         [0021]     According to another embodiment of the invention, each of the gasket release tools are extends through an angle in a circumferential direction such that three of the tools engage all of the rigid segments.  
         [0022]     According to another embodiment of the invention, each of the gasket release tools are extends through an angle in a circumferential direction such that four or more of the tools engage all of the rigid segments.  
         [0023]     According to another embodiment of the invention, an is provided apparatus for separating a pipe joint of the type including a first pipe received inside an enlarged socket of the second pipe and restrained therein by a resilient gasket carrying an annular array of toothed rigid segments which engage an outer surface of the first pipe to prevent withdrawal thereof. The apparatus includes: at least one gasket release tool having a body formed into an arcuate shape and adapted to be received between the first and second pipes; and a driving apparatus, including: a first driving ring adapted to be mounted around one of the pipes and sized to bear against the gasket release tool; a second driving ring adapted to be mounted around the other one of the pipes and sized to bear against the socket; and driving means for drawing the first and second driving rings together so as to drive the gasket release tool into the joint.  
         [0024]     According to another embodiment of the invention, each of the driving rings includes one or more arcuate rings segments adapted to be joined together.  
         [0025]     According to another embodiment of the invention, each of the ring segments has: an annular flange; and an annular band extending axially from said annular flange.  
         [0026]     According to another embodiment of the invention, the driving means includes at least one rod connecting the first and second driving rings, the rod engaging at least one fastener such that relative movement of the rod and the fastener causes axial motion of the driving rings.  
         [0027]     According to another embodiment of the invention, the driving means includes at least one actuator connecting the first and second driving rings.  
         [0028]     According to another embodiment of the invention, the driving means includes: at least one hydraulic cylinder connecting the first and second driving rings; and means for selectively supplying pressurized fluid to hydraulic cylinder.  
         [0029]     According to another embodiment of the invention, at least one of the driving rings includes at least one restraint disposed so as to engage the gasket release tool and prevent the gasket release tool from moving radially outward. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]     The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:  
         [0031]      FIG. 1  is a half-sectional view of two pipes connected together with a gasket having toothed metal segments;  
         [0032]      FIG. 2  is an end view of the gasket depicted in  FIG. 1   
         [0033]      FIG. 3  is a perspective view of a gasket release tool constructed in accordance with the present invention;  
         [0034]      FIG. 4  is a top view of the gasket release tool of  FIG. 3 ;  
         [0035]      FIG. 5  is a side view of the gasket release tool of  FIG. 3 ;  
         [0036]      FIG. 6  is an enlarged view of a portion of  FIG. 5 ;  
         [0037]      FIG. 7  is an end view of the gasket release tool of  FIG. 3 ;  
         [0038]      FIG. 8  is a cross-sectional view of the gasket release tool of the present invention being prepared to release a toothed gasket;  
         [0039]      FIG. 9  is a cross-sectional view of the gasket release tool inserted into the joint between the pipes shown in  FIG. 6 ;  
         [0040]      FIG. 10  is a top view of a gasket release tool having insertion markings thereon;  
         [0041]      FIG. 11  is a side view of the gasket release tool of  FIG. 10 ;  
         [0042]      FIG. 12  is a top view of a gasket release tool having a longitudinal stop bar disposed thereon;  
         [0043]      FIG. 13  is a side view of the gasket release tool of  FIG. 12 ;  
         [0044]      FIG. 14  is a top view of a gasket release tool having a lateral stop band disposed thereon;  
         [0045]      FIG. 15  is a side view of the gasket release tool of  FIG. 14   
         [0046]      FIG. 16  is a top view of a portion of a driving apparatus for use with the release tool;  
         [0047]      FIG. 17  is a perspective view of a portion of the driving apparatus shown in  FIG. 16 ;  
         [0048]      FIG. 18  is a partial end view of the driving apparatus shown in  FIG. 16 ;  
         [0049]      FIG. 19  is a side view of the driving apparatus shown in  FIG. 16   
         [0050]      FIG. 20  is a top view of a driving apparatus positioned to disassemble a pipe joint;  
         [0051]      FIG. 21  is a side view of the driving apparatus shown in  FIG. 20 ; and  
         [0052]      FIG. 22  is a schematic side view of a hydraulic apparatus for use with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0053]     Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  is a partial sectional view of a pair of first and second joined pipes  10  and  12 . The first pipe  10  has an enlarged-diameter socket  14  including an end face  16  which receives the smooth or spigot end  18  of the second pipe  12 . A gasket  20  including a plurality of metal segments  22  each having several teeth  24  (see  FIG. 2 ) is disposed between the first and second pipes  10  and  12  such that the teeth  24  bite into the outer surface  26  of the second pipe  12 . The number and spacing of the segments  22  will vary from gasket to gasket, however the circumferential spacing of the segments  22  will be generally constant as the diameter of the gasket  20  changes, i.e. a larger gasket will typically have more segments  22 .  
         [0054]      FIGS. 3-7  depict a gasket release tool  28  constructed according to the present invention. The gasket release tool  28  comprises a body  30  and a reinforcing collar  32 . The body  30  is a partially cylindrical shape and includes a forward edge  34 , a rear edge  36 , spaced-apart side edges  38  and  40 , and radially inner and outer surfaces  39  and  41 . The illustrated gasket release tool  28  has an overall length “L” in the longitudinal direction of about 30.5 cm (½ in.). The length L may be varied to suit a particular application so long as it is sufficient to reach the gasket  20  when inserted in the pipe joint. In another example, the length L may be about 10.2 cm (4 in.) The forward edge  34  includes a chamfer  43 , for example it may be about 0.8 mm ( 1/32 in.) wide at 45°. The material and thickness of the body  30  are chosen so that it will have adequate stiffness to resist buckling as it is driven in, yet still be thin enough to easily release the toothed segments  22 . One suitable material is 304 stainless steel of 16 gage thickness. The reinforcing collar  32  is made of an appropriate material which can be securely attached to the body  30  and which will have adequate strength to withstand repeated blows by a sledgehammer or other tool which is used to drive the gasket release tool  28 . One suitable material is 304 stainless steel, which has good hardness and corrosion resistance. In the illustrated example the reinforcing collar has a thickness “T” of about 1.27 cm (0.5 in.) thick in the radial direction and a length l of about 5 cm (2 in.). The reinforcing collar  32  may be attached to the body  30  in a position so that its rear face  42  is slightly offset in the longitudinal direction away from the rear edge  36  of the body. The reinforcing collar  32  is secured to the body with circumferential welds  44  and  46 . If desired, one or more weld beads (not shown) may be built up on the rear face  38  of the reinforcing collar  32  to harden it and reduce deformation under impact. The external surfaces of the gasket release tool  28  may be polished or otherwise provided with a smooth surface finish to reduce friction during use.  
         [0055]     Several of the dimensions of the gasket release tool  28  will vary depending upon the exact size and type of pipe that the gasket release tool  28  is to be used with. These include the inside radius “R” of the gasket release tool  28 , the circumferential angle “A” through which the gasket release tool  28  extends, and the number “N” of gasket release tools  28  required to disconnect a pair of joined pipes. The radius R is selected so that the gasket release tool  28  will fit against the outer surface of a spigot end of a pipe to be disconnected. This may be done by simply forming the body  30  of the gasket release tool  28  around the outside diameter of a pipe. The arc center of the gasket release tool  28  is offset by a gap distance “G” to prevent binding of the side edges  38  and  40  of adjacent gasket release tools  28  as they are placed around the pipes to be separated. The angle “A” is selected to be large enough so that the gasket release tool  28  will definitely engage several of the toothed metal segments  22  without the user having to manually align the gasket release tool  28  with the segments  22 , and small enough so that the gasket release tool  28  will not be too difficult to drive into the pipe joint. The number of gasket release tools  28  needed N is related to the angle A. For example if the angle A is 180°, then two gasket release tools  28  are needed to encircle a pipe joint, whereas if the angle A is 120°, then three gasket release tools  28  are required.  
         [0056]     The following Table 1 gives suitable approximate dimensions for gasket release tools  28  designed to be used with various diameter ANSI class 350 ductile iron pipes. These dimensions are merely an example and may be varied to suit a particular application.  
                               TABLE 1                       pipe inside   tool inside   angle       number of       diameter   radius, R   A   gap distance G   segments N                   20.3 cm (8 in.)   10.95 cm   180°   1.27cm (0.5 in.)   2       (4.3125 in.)       30.5 cm (12 in.)   16.19 cm   120°   1.27 cm (0.5 in.)   3       (6.375 in.)       40.6 cm (16 in.)   20.3 cm   120°   1.27 cm (0.5 in.)   3       (8 in.)       60.7 cm (24 in.)   30.5 cm    90°   1.27 cm (0.5 in.)   4       (12 in.)                  
 
         [0057]     The use of the gasket release tool  28  will now be described with respect to  FIGS. 8 and 9 . The gasket release tool  28  is prepared for use by placing it in contact with the outer surface  26  of the second pipe  12 , as shown in  FIG. 8 . As many gasket release tools  28  are used as needed to encircle the second pipe  12 . For example, if a 180° arc tool is used, then two identical gasket release tools  28  will be placed on opposite sides of the second pipe  12 . The gasket release tool  28  is slid forward until its forward edge  34  contacts the teeth  24  of the metal segments  22 . The gasket release tool  28  is then driven in by blows of a sledge hammer or other appropriate tool on the reinforcing collar  32 , until the body  30  of the gasket release tool  28  slides into the pipe joint and is interposed between the segments  22  and the second pipe  12 , as shown in  FIG. 9 . The chamfer  43  helps the body  30  of the gasket release tool  28  to slide under the teeth  24 . In this position, the gasket release tools  28  simultaneously release all of the segments  22  so that they cannot bite into the second pipe  12 . The friction force between the gasket release tool  28  and the outer surface  26  of the second pipe  12  is substantially less than the gripping force of the teeth  24 . Therefore, the first and second pipes  10  and  12  can be easily slid apart in the direction of the arrows in  FIG. 9 . Once the pipes  10  and  12  have been separated, the gasket release tool  28  may be removed. The first and second pipes  10  and  12  will be undamaged and ready for reuse. The gasket  20  may also be suitable for reuse in some situations.  
         [0058]     The gasket release tool  28  may optionally include stop means for indicating when the gasket release tool  28  has been driven in an adequate distance to disengage the gasket segments  22 .  FIGS. 10 and 11  illustrate a tool  128  in which the stop means comprises one or more indicia  50  that indicate the fully inserted position, such as a painted or printed marking such as a circumferential line, a circumferentially extending groove, or the like. Alternatively, the length L described above may selected so that the gasket release tool  28  disengages the segments  22  when it is driven to the point that the reinforcing collar  32  contacts the end face  16 . For example, the length L may be about 10.2 cm (4 in.). This eliminates the need for other stops, indicia, or measurement of the driving depth.  
         [0059]      FIGS. 12 and 13  depict another tool  228  wherein optional stop means include a longitudinal bar  52  having a stop face  54 . The longitudinal bar  52  may be simply welded to the outer surface of the tool  228  and has a length selected to contact the pipe end face  16  when the appropriate depth is reached.  
         [0060]      FIGS. 14 and 15  depict yet another tool  328  wherein optional stop means include a circumferential strap  56  having a stop edge  58 . The circumferential strap  56  may be simply welded to the outer surface of the tool  328  in a position so that the stop edge  58  contacts the pipe end face  16  when the appropriate depth is reached.  
         [0061]      FIGS. 16-19  illustrate a ring segment  402  of an exemplary driving apparatus  400  for use with the gasket release tool  28 . The ring segment  402  includes an annular flange  404 , which in the illustrated example is semi-circular, supported by an axially-extending annular band  406  which incorporates radially-extending connector flanges  408 . The ring segment  402  is constructed using suitable techniques and materials to withstand the expected loads in service. For example, it may be welded together from a material such as 1.27 mm (½ in.) thick steel. Optional gussets  409  may be used to provide additional support between the annular flange  404  and the annular band  406 , as shown in  FIG. 17 .  
         [0062]     Two or more ring segments  402  are connected together to form a first driving ring  410 . In the illustrated example, two semi-circular ring segments  402  are connected with bolts  412  through holes  414  in the connector flanges  408 . It is also possible that the first driving ring  410  could be made up from a greater number of ring segments each less than 180° in arc length.  
         [0063]     If desired, one or more restraints  416  made be disposed on the front face  417  of the annular flange  404 . The restraints  416  are spaced away from the inner edge  418  of the annular flange a distance approximately equal to the thickness of the reinforcing collar  32 . These restraints  416  help hold the gasket release tool  28  in position during use, as explained in more detail below.  
         [0064]      FIGS. 20 and 21  illustrate how the driving apparatus  400  is used to disassemble first and second joined pipes  10  and  12 . Initially, the gasket release tool  28  is prepared for use by placing it in contact with the outer surface  26  of the second pipe  12 , as described above. As many gasket release tools  28  are used as needed to encircle the second pipe  12 . For example, if a 180° arc tool is used, then two identical gasket release tools  28  will be placed on opposite sides of the second pipe  12 . The gasket release tool  28  is slid forward until its forward edge  34  contacts the teeth  24  of the metal segments  22 .  
         [0065]     The first driving ring  410  is secured around the second pipe  12 , with the annular flange  404  facing towards the socket  14  in contact with the reinforcing collar  32  of the gasket release tool  28 . The inside diameter of the annular flange  404  is chosen such that it can slide over the first pipe  10 , but that it will abut the gasket release tool  28  in an axial direction. The restraints  416 , if used, bear against the radially outer surface of the reinforcing collar  32 , so that it can not deflect outwards during a disassembly operation.  
         [0066]     A second driving ring  420 , substantially identical to the first driving ring  410 , is assembled around the first pipe  10 , behind the exterior of the socket  14 . Driving means which are capable of pulling the first and second driving rings  410  and  420  together then connected between the first and second driving rings  410  and  420 . In the illustrated example, the driving means comprise externally threaded rods  422  which extend through openings  424  (see  FIG. 18 ) in the first and second driving rings  410  and  420 , respectively. Nuts  426  are threaded on opposite ends of the threaded rods  422 .  
         [0067]     The gasket release tool  28  is then driven in by using the driving means to pull the first and second driving rings  410  and  420  together, for example by tightening the nuts  426  with an appropriate tool. The second driving ring  420  will bear against the socket  14  while the first driving ring  410  bears against the gasket release tool  28  to cause it to slide into the pipe joint and be interposed between the segments  22  and the second pipe  12 , as shown in  FIG. 9 . The driving means provide high mechanical advantage so that a high driving force can be generated with a relatively low amount of effort by an operator. The gasket release tool  28  is also less likely to suffer wear or damage since no sledge hammer or other impact tool is used. The chamfer  43  helps the body  30  of the gasket release tool  28  to slide under the teeth  24 . In this position, the gasket release tools  28  simultaneously release all of the segments  22  so that they cannot bite into the second pipe  12 . The friction force between the gasket release tool  28  and the outer surface  26  of the second pipe  12  is substantially less than the gripping force of the teeth  24 . Therefore, the first and second pipes  10  and  12  can be easily slid apart in the direction of the arrows in  FIG. 9 . Once the pipes  10  and  12  have been separated, the gasket release tool  28  may be removed. The first and second pipes  10  and  12  will be undamaged and ready for reuse. The gasket  20  may also be suitable for reuse in some situations.  
         [0068]      FIG. 22  illustrates a known type of portable hydraulic apparatus  428  comprising a double-acting cylinder  430  and a hand pump  432 , connected by appropriate piping and valves. Opposite ends of the cylinder  430  may be connected to the first and second driving rings  410  and  420  to serve as the driving means instead of the threaded rod  422 .  
         [0069]     The gasket release tool  28  and method described above results in a substantial savings of time and cost compared to prior art methods. It allows the disconnection of pipe joints in a matter of minutes instead of hours required by prior art methods. The gasket release tool  28  is durable and reusable. Furthermore, the tool allows the reuse of some or all of the piping components, which substantially reduces expenses.  
         [0070]     The foregoing has described a gasket release tool and a method for disconnecting pipes joined with a toothed gasket. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.