Patent Abstract:
A pipe pulling technique where an adaptor is attached to the end of the pipe prior to the pipe being pulled underground, for example through a drilled hole. Attaching the adaptor to the pipe end prior to the pipe being pulled underground is faster and reduces danger to workers compared to the conventional process of attaching the adaptor to the end of the pipe after the pipe has been pulled underground.

Full Description:
FIELD 
       [0001]    This description relates to pulling pipe underground beneath an obstacle from a first side to a second side of the obstacle. 
       BACKGROUND 
       [0002]    It is known to pull a pipe through a borehole drilled in the earth beneath an obstacle from a first side to a second side of the obstacle This process can be used to run the pipe underneath the obstacle, such as a river, a roadway, or the like, from one side to the other. 
         [0003]    In the conventional process, a pull head is attached to the pipe at the first side. The pipe is then pulled underground through the borehole from the first side to the second side. At the second side, the pull head is removed from the pipe, a section of pipe is then cut from the pipe end, and a pipe adaptor is then fused to the end of the pipe. The end of a new section of pipe is then joined to the pipe adaptor to continue the pipeline. 
         [0004]    The fusing or welding of the pipe adaptor to the end of the pipe at the second side typically occurs within a trench or bell hole that is dug at the second side. The trench accommodates the fusing or welding equipment, the pipe cutting equipment, the pipe pulling equipment and other equipment, as well as personnel operating the equipment. The trench or bell hole is typically deep, for example 6 to 8 feet deep. Therefore, the sides of the trench or bell hole need to be reinforced to prevent collapse of the trench onto personnel working in the trench. In addition, the trench can be muddy which increases the danger to personnel working in the trench. Therefore, the process of fusing or welding the pipe adaptor to the end of the pipe at the second side within the trench can be a lengthy process and it can be dangerous to personnel. 
       SUMMARY 
       [0005]    A pipe pulling technique is described where the adaptor is attached to the end of the pipe at the first side prior to the pipe being pulled underground, for example through a pre-drilled hole. The attachment of the adaptor to the pipe at the first side occurs above ground, e.g. not within a trench. As a result, attaching the adaptor to the pipe end at the first side while the pipe end is above ground, and prior to pulling the pipe underground, is faster and reduces danger to workers compared to the conventional process of attaching the adaptor at the second side within a trench. 
         [0006]    In one embodiment, the pipe and adaptor are both made of plastic, and the adaptor is attached to the pipe end by fusing the end of the adaptor to the end of the pipe. However, the pipe and the adaptor can be made of any materials, including but not limited to metal, that are suitable to permit attaching the adaptor and the pipe together in any manner that satisfies the intended application(s) of the pipe. 
         [0007]    In one embodiment, the pipe can be part of a pipeline that is intended to carry liquids and/or gases. In another embodiment, the pipe can be part of pipeline through which cables, for example electrical and/or fiber optic cables, can be run. 
         [0008]    The adaptor can be configured to connect to an end of any pipeline component at the second side that is intended to be part of the pipeline. In one embodiment, the adaptor can be a plastic pipe adaptor that is configured to connect to an end of a second plastic pipe at the second side. However, the pipeline component can be a section of pipe, a valve, a coupler that splits flow through the first pipe into multiple flow paths or that gathers flow from multiple flow paths into a single path for flow through the first pipe, and other components used in pipelines. 
         [0009]    In one embodiment, a method of pulling a pipe underground from a first side to a second side includes at the first side, attaching an adaptor to an end of the pipe, the adaptor being configured to connect to a pipeline component at the second side. At the first side, attaching a pull head to the adaptor. The pipe is then pulled underground from the first side to the second side by applying a pulling force to the pull head from the second side. At the second side, the pull head is removed, and the pipeline component is connected to the adaptor. 
         [0010]    As used herein, the term “first side” refers to the side at which the end of the pipe is first polled underground, while the “second side” refers to the side at which the end of the pipe exits after the pipe is pulled underground from the first side. From the perspective of the drilling equipment used to drill the hole through which the pipe is pulled, the first side may be considered an “exit side” as it is the side through which the drill exits after drilling the hole, while the second side may be considered an “entrance side” as it is the side through which the drill initially enters the earth for drilling the hole. Alternatively, from the perspective of the pipe to be pulled underground, the first side may also be considered an “entrance side” as it is the side through which the end of the pipe being pulled initially enters the hole through which the pipe is being pulled, while the second side may also be considered an “exit side” as it is the side through which the end of the pipe exits the hole after being pulled underground. 
         [0011]    In another embodiment, a method of pulling a pipe underground from a fast side to a second side includes at the first side, fusing or welding a first end of a pipe adaptor to an end of the pipe, a second end of the pipe adaptor being configured to connect to a pipeline component at the second side. In addition, at the first side, a pull head is attached to the pipe adaptor after the pipe adaptor is fused to the end of the pipe. Thereafter, the pipe is pulled underground from the first side to the second side by applying a pulling force to the pull head from the second side. At the second side, the pull head is removed, and the pipeline component is connected to the end of the pipe adaptor after removing the pull head. 
         [0012]    In still another embodiment, a pull head is provided that is used to pull a pipe underground from a first side to a second side. The pull head includes a pull head collar formed by at least first and second shell pieces that are detachably connectable to one another, where the at least first and second shell pieces are sized to surround an end of the pipe when the at least first and second shell pieces are connected together. Each of the at least first and second shell pieces includes an interior surface and a channel is firmed on the interior surface of each of the at least first and second shell pieces, wherein when the at least first and second shell pieces are connected together the channels of the at least first and second shell pieces align with one another to form a substantially continuous circumferential channel that in use receives a flange on the pipe. In addition, a pull head cap is connected to first ends of the at least first and second shell pieces when the at least first and second shell pieces are connected together, wherein in use the pull head cap connects to a pull line that applies a pulling force to the pull head. 
       DRAWINGS 
       [0013]      FIG. 1  illustrates an example application of the pipe pulling technique described herein. 
         [0014]      FIG. 2  is an exploded perspective view of the adaptor attached to the end of the pipe and the parts of the pull head. 
         [0015]      FIG. 3  is a cross-sectional side view of the adaptor attached to the end of the pipe and the pull head mounted in place. 
         [0016]      FIG. 4  is a perspective view of the pull head mounted in place. 
         [0017]      FIG. 5  illustrates an example of a pipe that is connected to the adaptor at the exit side. 
         [0018]      FIG. 6  illustrates another example of a pull head. 
         [0019]      FIG. 7  illustrates another example of a pull head. 
         [0020]      FIG. 8  illustrates still another example of a pull head. 
         [0021]      FIG. 9  illustrates still another example of a pull head. 
         [0022]      FIG. 10  is a side view of another embodiment of an adaptor attached to the end of the pipe. 
         [0023]      FIG. 11  is a cross-sectional side view of another embodiment of an adaptor attached to the end of the pipe. 
         [0024]      FIG. 12  is an exploded view of another embodiment of a pull head. 
         [0025]      FIG. 13  shows the pull head of  FIG. 12  assembled. 
     
    
     DETAILED DESCRIPTION 
       [0026]      FIG. 1  illustrates an example application of the pipe pulling technique described herein. In this example, a pipeline needs to be extended underneath an obstacle  10 , such as, but not limited to, a river. The obstacle  10  could be a roadway, or any other obstacle under which one may wish to extend a pipeline. The pipeline can be intended to carry liquids and/or gases, or the pipeline can act as a conduit through which cables, for example electrical and/or fiber optic cables, can be run underneath the obstacle  10 . 
         [0027]    A hole  14  is initially drilled into the ground underneath the obstacle  10 , with the hole  14  extending from a first side  16  on one side of the obstacle  10  to a second side  18  on the other side of the obstacle  10  using any suitable directional drilling technique. In one embodiment, the hole  14  is drilled by directional drill equipment the employs a drill that drills into the earth starting from the second side  18  and that exits the first side  16 . Directional drilling is well known in the art. Thereafter, a pipe  20  that forms part of the pipeline is pulled underground through the hole  14  from the first side  16  to the second side  18  as indicated by the arrows in  FIG. 1 . As discussed in further detail below, prior to pulling the pipe  20 , an adaptor  30  (seen in  FIGS. 2-3 and 5 ) is attached to an end of the pipe  20  at the first side  16 , and a pull head  32  is secured around the adaptor  30  at the first side  16 . A pull line (not shown), such as a cable or rope or pipe, is affixed to the pull head  32  and applies a pulling force to the pull head  32  and the pipe  20  via a suitable pulling mechanism (not shown) located at or near the second side  18 . 
         [0028]    The adaptor  30  will now be described with reference to  FIGS. 2-5 . In general, the adaptor  30  is configured to be attached to the pipe  20  at or near the first side  16  while the end of the pipe  20  is above ground and prior to the pipe  20  being pulled underground. The adaptor  30  is also configured to connect to a pipeline component at the exit side  18  that is intended to form part of the pipeline. For example, the pipeline component can be another section of pipe, a valve, a coupler that splits flow through the pipe  20  into multiple flow paths or that gathers flow from multiple flow paths into a single path for flow through the pipe  20 , and other pipeline components used in pipelines.  FIG. 5  illustrates the pipe  20  and the adaptor  30  after being pulled to the second side  18  and connected to a pipeline component  34  in the form of another section of pipe. 
         [0029]    The adaptor  30  and the pipe  20  can be attached to one another in any manner so that the adaptor  30  and the pipe  20  are attached together substantially permanently and a liquid-tight joint is formed therebetween. For example, the adaptor  30  and the pipe  20  can each be made of plastic and the adaptor  30  and the pipe  20  can be fused, i.e. “welded”, to one another whereby a molecular bond creating a liquid-tight joint is formed between the adaptor  30  and the pipe  20 . Fusing of a plastic adaptor to a plastic pipe is well known in the art. If the adaptor  30  and the pipe  20  are made of metal, the adaptor  30  and the pipe  20  could be welded together using conventional metal welding techniques. 
         [0030]    Referring to  FIGS. 2 and 3 , in one embodiment the adaptor  30  is a substantially cylindrical, tubular structure, and the pipe  20  is also substantially cylindrical. The adaptor  30  has a first end  40 , a second end  42 , an exterior surface  44  (best seen in  FIG. 5 ), and an interior surface  46 . The first end  40  is attached, for example fused, to an end  48  of the pipe  20  as shown in  FIGS. 3 and 5  to form a liquid-tight joint  49  therebetween. In the illustrated example, a thickness t a  of the adaptor  30  measured between the exterior surface  44  and the interior surface  46  at the first end  40  is substantially equal to the thickness t p  of the pipe  20  at the end  48  so that the interior surface  46  substantially forms a continuation of the interior surface of the pipe  20 . However, in some embodiments, the thickness t s  can be different than the thickness t p . 
         [0031]    Between the first end  40  and the second end  42 , the exterior surface  44  of the adaptor  30  is provided with at least one flange  50  that extends radially outwardly from the exterior surface  44 . The flange  50  is configured to engage with the pull head  32  to transfer a pulling force acting on the pull head  32  to the adaptor  30  and to the pipe  20 . More than one flange  50  can be used as described further below with respect to  FIG. 10 . The flange  50  can have any configuration that is suitable for achieving this function. In one embodiment, the flange  50  is circumferentially continuous around the entire circumference of the adaptor  30  although other configurations are possible. The flange  50  can be located anywhere along the length of the adaptor  30  but in the illustrated example, the flange  50  is located closer to the second end  42  than it is to the first end  40 . 
         [0032]    Referring to  FIG. 3 , a step  51  is formed to the rear of the flange  50 , for example integrally extending from the flange  50  and located between the flange  50  and the first end  40 . The step  51  helps to reduce loading applied to the flange  50  by the pull head  32  so that the flange  50  does not take all of the load. 
         [0033]    Still referring to  FIG. 3 , the interior surface  46  defines a portion extending from the first end  40  toward the second end  42  that has a substantially constant diameter D 1 . The constant diameter portion extends up to approximately a location of a front edge  52  of the flange  50 , where the interior surface  46  increases in diameter to form a portion having a substantially constant diameter D 2  that is larger than the diameter D 1 . The transition between the two diameters D 1  and D 2  forms a shoulder  54 . Due to the increase in diameter, the thickness of the adaptor  30  at the second end  42  is less than the thickness t a  at the first end  40 . In some embodiment, an end of a mechanism  53  for connecting the pipeline component  34  (see  FIG. 5 ) can abut against the shoulder  54  when the pipeline component  34  is connected to the adaptor  30 . In other embodiments, the mechanism  53  does not abut against the shoulder  54  as shown in  FIG. 5 , in which case the shoulder  54  can be eliminated and the interior surface  46  can have a substantially constant diameter D 1  from end to end. 
         [0034]      FIG. 10  illustrates another embodiment of the adaptor  30  that is attached to the end of the pipe  20 . In this embodiment, the adaptor  30  includes two or more flanges  50   a ,  50   b  that are spaced apart from one another. Each flange  50   a ,  50   b  can be received within a corresponding channel, similar to the channel  70  discussed further below, formed by the pull head  32 . In the illustrated example, the flanges  50   a ,  50   b  can have the same or similar thickness t f  and the same of similar height h f  from the exterior surface  44  of the adaptor  30 . A larger number of flanges can be utilized and the flanges can be spaced apart from one another or the flanges can abut one another. In addition, the flanges  50   a ,  50   b  can have different thicknesses t f  and heights f f . As discussed further below, the pull head  32  would be modified accordingly to engage with the flanges  50   a ,  50   b . Any number and sizes of the flanges  50   a ,  50   b  can be used on the adaptor  30  to give added strength to pull against while pulling the pipe underground. 
         [0035]      FIGS. 3 and 10  illustrate the flange(s)  50 ,  50   a ,  50   b  as being rectangular in side view. However, the flanges  50 ,  50   a ,  50   b  can have other shapes including, but not limited to, round, triangular, etc. when viewed in side view. In addition, although the flanges  50   a ,  50   b  are illustrated as being of the same size, the flanges  50   a ,  50   b  can have different sizes. 
         [0036]    In addition, referring to  FIG. 11 , the use of one or more flanges on the adaptor is not required. Instead,  FIG. 11  illustrates an adaptor  30 ′ that includes one or more channels  180  formed in the outer surface thereof. In one embodiment, the channel(s)  180  is circumferentially continuous about the periphery of the adaptor  30 ′. However, the channel(s)  180  need not be circumferentially continuous but can be interrupted by one or more non-recessed portions. In some embodiments, if required to accommodate pulling forces and forces during use, the thickness of the end of the adaptor  30 ′ may be increased to better accommodate the channel(s)  180 . If a channel(s)  180  is used, the pull heads described below will be modified to include corresponding one or more radially inwardly extending flanges that extend into the channel(s)  180  to secure the pull head  32  to the adaptor  30 ′ and transfer the pulling forces to the adaptor  30 ′. 
         [0037]    Referring now to  FIGS. 2-4 , an example of the pull head  32  will now be described. The pull head  32  is configured to detachably connect to the adaptor  30  to apply pulling forces to the adaptor  30  and the pipe  20  to pull the adaptor  30  and the pipe  20  underground to the exit side  18 . The pull head  32  can have any configuration that is suitable for achieving this function. 
         [0038]    In the embodiment illustrated in  FIGS. 2-4 , the pull head  32  includes a plurality of pieces that are connectable together. The pull head  32  can have any number of pieces that are connectable together in order to perform the intended functions of the pull head  32 . In one embodiment, the pull head  32  includes a pull head collar  58  that is removably disposable around the adaptor  30 , and a pull head cap  86  that connects to the pull head collar  58 . However, other configurations are possible. 
         [0039]    In the example illustrated in  FIGS. 2-4 , the pull head collar  58  includes a plurality of, for example first and second, shell pieces  60   a ,  60   b  that are detachably connectable to one another so as to surround the adaptor  30  when the shell pieces  60   a ,  60   b  are connected together. When there are two of the shell pieces  60   a ,  60   b , each of the shell pieces  60   a ,  60   b  can be configured as a half shell surrounding about half of the adaptor  30 . However, in the case of two shell pieces, the shell pieces  60   a ,  60   b  can be configured to cover more or less than half of the adaptor  30 . For example, the shell pieces  60   a ,  60   b  can be sized at ratios of 75/25, 60/40, etc. 
         [0040]    For sake of convenience in describing the concepts, the description will hereinafter refer to first and second shell pieces  60   a ,  60   b  although a different number of shell pieces can be used, and the shell pieces  60   a ,  60   b  sized at a 50/50 ratio, i,e, the shell pieces  60   a ,  60   b  are half shells. However, other configurations are possible. The first and second shell pieces  60   a ,  60   b  are substantially identical in construction to one another. Each shell piece  60   a ,  60   b  forms a half cylinder with an exterior surface  62 , an interior surface  64 , a first end  66 , and a second end  68 . In the illustrated example, when the pull head collar  58  is mounted in place, the first ends  66  terminate at approximately the joint  49  so that the shell pieces  60   a ,  60   b  only overlap the adaptor  30  and do not overlap, or only minimally overlap, the pipe  20 . However, the shell pieces  60   a ,  60   b ) can be sized such that the first ends  66  extend past the joint  49  so that the shell pieces  60   a ,  60   b  overlap the adaptor  30  as well as a portion of the pipe  20 . 
         [0041]    Referring to  FIGS. 2 and 3 , a channel  70  is formed on the interior surface  64  of each of the shell pieces  60   a ,  60   b  so that when the shell pieces  60   a ,  60   b  are connected together around the adaptor  30 , the channels  70  of the shell pieces  60   a ,  60   b  align with one another to form a substantially continuous circumferential channel that in use receives the flange  50  of the adaptor  30 . In addition to the channel  70 , the shell pieces  60   a ,  60   b  each include a smaller channel  71  so that when the shell pieces  60   a ,  60   b  are connected together around the adaptor  30 , the channels  71  of the shell pieces  60   a ,  60   b  align with one another to form a substantially continuous circumferential channel that in use receives the step  51  of the adaptor  30   
         [0042]    Referring to  FIGS. 2 and 4 , side edges  72 ,  74  of each shell piece  60   a ,  60   b  form mating surfaces that abut against and mate with one another to form a joint  76 . Fastener holes  78  are formed along the lengths of the side edges  72 ,  74  that allow passage of fasteners  80 , such as bolts, that removably secure the shell pieces  60   a ,  60   b  to one another surrounding the adaptor  30 . 
         [0043]    The interior surface  64  of each shell piece  60   a ,  60   b  is also formed with a friction enhancement section  82 , best seen in  FIGS. 2 and 3 , that is configured to enhance frictional engagement between the pull head  32  and the exterior surface  44  of the adaptor  30 . The friction enhancement section  82  can have any configuration that is suitable for achieving this function. In the illustrated example, the friction enhancement section  82  can be formed by teeth, knurling, rubber pads, or other friction enhancement features that engage with the exterior surface  44  of the adaptor  40 . The exterior surface  44  opposite the friction enhancement section  82  can be substantially smooth or the exterior surface  44  can be provided with friction enhancement features that engage with the friction enhancement features of the friction enhancement section  82 . The friction enhancement features can be integrally formed with the interior surface  64  of each shell piece  60   a ,  60   b , or the friction enhancement features can be formed by a separate layer of material that is fixed to the interior surface  64  or simply disposed between the interior surface  64  and the exterior surface  44 . In addition, in the illustrated example, the friction enhancement section  82  extends from one side edge  72  to the other side edge  74 , is spaced inwardly from and does not extend all the way to the first end  66 , and extends toward but stops short of the channel  70 . However, other sizes and arrangements of the friction enhancement section  82  are possible. 
         [0044]    Returning to  FIGS. 2 and 3 , each of the shell pieces  60   a ,  60   b  further includes an inwardly projecting flange  84  adjacent to the end  68  thereof. When the shell pieces  60   a ,  60   b  are connected together, the flanges  84  align with one another to form a substantially continuous circumferential flange the purpose of which is discussed further below. 
         [0045]    The pull head cap  86  of the pull head  32  is disposed at the front end of the pull head  32  and is connected to the end  68  of the shell pieces  60   a ,  60   b  when the shell pieces  60   a ,  60   b  are connected together around the adaptor  30 . When the shell pieces  60   a ,  60   b  are disconnected, the pull head cap  86  can be disconnected from the shell pieces  60   a ,  60   b . In another embodiment, the pull head cap  86  can be integrally or permanently attached to one or more of the shell pieces  60   a ,  60   b . In use, the pull head cap  86  connects to a pull line, such as a cable or rope or pipe, that applies a pulling force to the pull head  32 . The pull head cap  86  can have any configuration that is suitable for achieving the functions of the pull head cap  86 . In the illustrated example, the pull head cap  86  has a housing member  88 , a pull eye  90 , and a securement disk  92 . 
         [0046]    Referring to  FIG. 3 , the housing member  88  is a generally hollow, circular disk with a convex front surface  94  and a rearwardly extending flange  96 . A slot  98  is formed in the front surface  94  through which a portion of the pull eye  90  extends forwardly. The pull eye  90  includes a hole  100  for connecting to the pull line. A disk  102  of the pull eye  90  is disposed within the housing member  88  and includes a curved surface  104  that engages with an interior curved surface of the front surface  94 . 
         [0047]    The securement disk  92  is configured to close the open end of the housing member  88 . In particular, the securement disk  92  includes a disk  106  that closely fits within the flange  96  and the securement disk  92  and the housing member  88  are then fastened to one another by welding the disk  106  to the flange  96 . To the rear of the disk  106  is a second disk  108  that has a diameter that is less than, greater than, or equal to the diameter of the disk  106 . The disks  106 ,  108  define therebetween a circumferential channel  110  that in use receives the substantially continuous circumferential flanges  84  of the shell pieces  60   a ,  60   b  to secure the pull head cap  86  to the shell pieces  60   a ,  60   b.    
         [0048]    In some embodiments, it is desirable to prevent ingress of moisture, soil and other contaminants into the interior of the pipe  20  when pulling the pipe  20  underground. The joint  49  between the adaptor  30  and the pipe  20  is liquid tight and prevents ingress of moisture, soil and other contaminants. In addition, suitable sealing can be provided between the pull head  32  and the adaptor  30  to prevent ingress of moisture, soil and other contaminants. For example, in the illustrated example, a circumferential sealing groove  112  can be formed in the outer surface of the disk  108  that is designed to receive a sealing gasket therein which seals with the interior surface  64  of the shell pieces  60   a ,  60   b . In addition, the interior surface  64  of each shell piece  60   a ,  60   b  can be formed with a sealing groove  114  which combine to form a circumferential sealing groove that is designed to receive a sealing gasket therein which seals with the exterior surface  44  of the adaptor  30 . However, other sealing arrangements and configurations can be utilized including a seal between the rear surface of the disk  108  and the front facing surface of the adaptor  30 . 
         [0049]    Referring to  FIG. 6 , another example of a pull head  132  is illustrated. The pull head  132  can be generally similar in construction to the pull head  32  in that the pull head  132  includes the pull head collar  58  formed by the shell pieces  60   a ,  60   b  , as well as including the pull head cap  86 . However, in this embodiment, the shell pieces  60   a ,  60   b  are hinged to one another along one of the side edges  72 ,  74 , for example the side edge  74  in this example. The shell pieces  60   a ,  60   b  are connected together by one or more hinges  134 , for example two of the hinges  134 , that permits the shell piece  60   a  to open or close relative to the shell piece  60   b  while the shell pieces  60   a ,  60   b  remain connected to one another.  FIG. 6  shows the shell piece  60   a  at an open position relative to the shell piece  60   b . The shell piece  60   a  can swing to a closed position relative to the shell piece  60   b  so as to fit around the adaptor  30  similar to what is shown in  FIGS. 3 and 4 . This embodiment eliminates the need for a second row of fasteners  80  along the side edges  74  of the shell pieces  60   a ,  60   b . The construction of the shell pieces  60   a ,  60   b  of the pull head collar  58  and the pull head cap  86  are otherwise similar to the construction described in  FIGS. 2-4 . 
         [0050]      FIG. 7  illustrates another example of a pull head  140  that has a pull head collar  141  that is formed by three shell pieces  142   a ,  142   b ,  142   c . In this example, each shell piece  142   a ,  142   b ,  142   c  covers approximately 120 degrees, and when the shell pieces  142   a ,  142   b ,  142   c  are connected together, they combine to encircle the adaptor  30 . Each shell piece  142   a ,  142   b ,  142   c  is configured generally similarly to the shell pieces  60   a ,  60   b , including each shell piece  142   a ,  142   b ,  142   c  having the channel  70  and the smaller channel  71  the purpose of which is the same as for the shell pieces  60   a ,  60   b . In addition, the pull head  140  can include a pull head cap  144  that can be identical in construction to the pull head cap  86 . 
         [0051]      FIG. 8  illustrates another example of a pull head  150  that includes a pull head collar  151  that is formed by at least two shell pieces  152   a ,  152   b , and a pull head cap  154 . For sake of convenience, the pipe  20  is not illustrated in  FIG. 8 . In this example, the shell pieces  152   a ,  152   b  have a length that is shorter than the length of the shell pieces  60   a ,  60   b  so that an end  156  of each shell piece  152   a ,  152   b  stops well short or forward of the first ends  40  of the adaptor  30 . In addition, in this example, the shell pieces  152   a ,  154  include the channel  70  to receive the flange  50  but do not include the smaller channel  71  for the step  51  on the adaptor  30 . The second end  42  of the adaptor  30  is also spaced from the disk  108  of the pull head cap  154 . 
         [0052]    With continued reference to  FIG. 8 , the pull head cap  154  is generally similar in construction to the pull head cap  86 . However, the disk  106  does not fit within the flange  96 . Instead, the end of the flange  96  abuts against the face of the disk  106  and the end of the flange  96  is then welded to the face of the disk  106 . 
         [0053]      FIG. 9  illustrates another example of a pull head  160  that includes a pull head collar  162  and a pull head cap  164 . For sake of convenience, the pipe  20  is not illustrated in  FIG. 9 . The pull head collar  162  can be formed by two or more shell pieces that are constructed as discussed above for  FIGS. 2-4 and 6-8 . In this embodiment, the pull head cap  164  is a single piece construction. In addition, instead of having a pull eye  90 , the pull head cap  164  includes a central boss  166  that extends from a disk  168 . The central boss  166  includes a threaded aperture  170 . In use, a threaded connector (not shown) of a pull line will thread into the aperture  170  to secure the pull line to the pull head  160  while pulling the pipe underground. 
         [0054]      FIGS. 12 and 13  illustrate an embodiment of a pull head  200  that is formed by multiple shell pieces  202   a ,  202   b  that are connectable together around the adaptor using the fasteners  80  (not shown in  FIGS. 12 and 13 ). The interior construction of the shell pieces  202   a ,  2026   b  can be substantially similar to the interior construction of the shell pieces of the pull heads  32 ,  132 ,  142 , etc. described above. In this embodiment, the pull head  200  includes a pull head cap  204  that is formed by pull head cap pieces  206   a ,  206   b  that are integrally formed with the respective shell pieces  202   a ,  202   b  so that the shell piece  202   a  and the pull head cap piece  206   a  together form a single, unitary construction, and the shell piece  202   b  and the pull head cap piece  206   b  together form a single, unitary construction. Each pull head cap piece  206   a ,  206   b  includes an opening  208  formed therethrough, where the openings  208  align with one another when the shell pieces  202   a ,  202   b  are secured around the adaptor to form a pull eye. Optionally, one or more fastener openings  210  can be provided on the pull head cap pieces  206   a ,  206   b  that receive fasteners, such as bolts or screws, help fasten the pull head cap pieces  206   a ,  206   b  to one another when the shell pieces  202   a ,  202   b  are secured around the adaptor. 
         [0055]    An example operation and use will now be described with reference to the embodiment illustrated in  FIGS. 2-4 . The embodiments in  FIGS. 6-9  operate in a similar manner. This example will assume that the pipe  20  and the adaptor  30  are plastic and that the pipe  20  and adaptor  30  are fused to one another. However, a similar operation can be performed when the adaptor  30  is welded to the end of the pipe. Referring to  FIG. 1 , the pipe  20  needs to be pulled underground from the first side  16  to the second side  18  underneath the obstacle  10 . At the first side  16 , the end  40  of the adaptor  30  is fused to the end  48  of the pipe  20 , for example while the end  48  of the pipe  20  is disposed above ground. Therefore, the workers and equipment that are performing the fusing are working above ground instead of within a deep trench as with the prior art. Thereafter, the pull head  32  is secured around the adaptor  30  as shown in  FIGS. 3 and 4 . The pulling force is then applied to the pull head  32  from the second side  18 . The pulling force pulls the pipe  20  into and through the hole  14  until the pull head  32  emerges from the second side  18 . The pull head  32  is then removed from around the adaptor  30  which remains in place fused with the pipe  20 . Thereafter, the pipeline component  34  is installed to continue the pipeline as shown in  FIG. 5 . In this example, installing the pipeline component  34  occurs without having to cut-off any part of the pipe  20  or the adaptor  30  at the second side  18 , or fusing an adaptor to the pipe  20  at the second side  18  within a deep trench. So once the adaptor  30  is fused to the pipe  20  at the first side  16  and the pipe is pulled underground to the second side  18 , the pull head  32  can be removed and connection to the pipeline component  34  can occur without having to cut the pipe  20  or the adaptor  30  or fuse an adaptor to the pipe at the second side  18 . 
         [0056]    The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Technology Classification (CPC): 5