Abstract:
A method of attaching a branch outlet fitting to a metal pipe buried beneath the earth&#39;s surface while causing reduced disturbance to the earth above the pipe, comprising digging a vertical excavation from the earth&#39;s surface to expose a short length of the pipe; positioning a first fitting portion on a lower surface of the pipe; positioning a second fitting portion on an upper surface of the pipe in alignment with the first fitting portion, the first and second fitting portions having welding material thereon adjacent the pipe surfaces and each other; and from the earth&#39;s surface, activating the welding material to physically and sealably secure the fitting portions to the pipe and to each other.

Description:
REFERENCE TO PENDING APPLICATIONS 
       [0001]    This application is not based upon any pending domestic or international patent applications. 
       FIELD OF THE INVENTION 
       [0002]    The present invention is generally directed toward a method for attaching a self-contained keyhole weld fitting and apparatus. More specifically, the present invention provides an improved fitting and method of use providing a branch outlet which can be physically and sealably secured to an underground pipe while causing less disturbance to the earth above the pipe than using a traditional fitting and excavation. 
       BACKGROUND OF THE INVENTION 
       [0003]    Additional outlets must often be added to underground pipelines or pipes. This is typically accomplished by creating an excavation from the earth&#39;s surface down to the pipe to be tapped. In locations where disturbance of the surface is not an issue an excavation is made which exposes the underground pipe and is large enough to accommodate a fitting along with a welder and his equipment. The fitting is temporarily held in place by various means while the welder physically and sealably secures the fitting by welding it to the exterior of the pipe. Once the fitting has been welded in place the means by which the fitting is temporarily held in place are removed. At this point an operation called a hot tap is carried out wherein a portion of the pipe is cut and removed such that the fitting is now in fluid communication with the interior of the pipe. This is accomplished while the pipe is under pressure carrying gas or liquids. 
         [0004]    In many situations, such as pipes located under busy city streets, the surface disturbance caused by an excavation large enough to accommodate the fitting and welder are unacceptable. In these types of situations a much smaller excavation is created extending from the earth&#39;s surface down to just below the underground pipe being tapped. The excavation is deep enough to expose the lower surface of the pipe. The diameter of the excavation is typically just large enough to accommodate the fittings to be mounted on the pipe. A first portion of the fitting is seated on the lower surface of the pipe. The second portion of the fitting is then placed on a top portion of the pipe. The first and second portions are aligned with one another and secured to one another and the pipe using bolts. These bolt-on fittings are sealed to the pipe by elastomeric seals captured between the fitting and pipe. While these bolt-on fittings allow an underground pipe to be tapped with minimal disturbance to the surface, the elastomeric seals tend to deteriorate over time leading to leaks between the pipe and the fitting. 
         [0005]    There is a long felt need in the pipeline industry for a fitting and method which would provide a permanent welded seal for a branch outlet while accessing the existing pipe using a keyhole excavation. 
         [0006]    For additional information relating to excavation and fittings for tapping underground pipes, reference may be had to the following previously issued United States patents. 
         [0000]    
       
         
               
               
               
             
           
               
                   
               
               
                 Patent Number 
                 Inventor 
                 Title 
               
               
                   
               
             
             
               
                   847,594 
                 McCreary 
                 Hose or Pipe Mender 
               
               
                 3,178,793 
                 Rosengarten 
                 Apparatus For Sealing Mains 
               
               
                   
                 Jr. et al. 
               
               
                 4,323,526 
                 Hilbush III 
                 Method For Sealing Pipe Joints 
               
               
                 4,610,439 
                 Burghardt 
                 Service Saddle U-Bolt Installation Holder 
               
               
                 4,647,073 
                 Kosaka 
                 Clamping Device For Underground Pipes 
               
               
                 4,832,069 
                 Gale et al. 
                 Tapping Subterranean Pipes 
               
               
                 5,659,935 
                 Lo-Pinto 
                 Apparatus For Installing A Branch 
               
               
                   
                 et al. 
                 Tapping On A Pipe 
               
               
                 6,142,165 
                 Wartel et al. 
                 Method and Apparatus For Installing 
               
               
                   
                   
                 A Branch Connector From 
               
               
                   
                   
                 The Top Of An Excavation 
               
               
                 6,669,406 
                 Hutton et al. 
                 Method and Apparatus For Underground 
               
               
                   
                   
                 Connection of Pipe 
               
               
                 6,705,801 
                 Kiest Jr. 
                 Apparatus and Method For Providing 
               
               
                   
                   
                 Access To Buried Pipeline 
               
               
                 7,001,106 
                 Burnham 
                 Installation of Service Connections 
               
               
                   
                 et al. 
                 For Sensors or Transmitters In 
               
               
                   
                   
                 Buried Water Pipes 
               
               
                 2006/0002765 
                 Hutton et al. 
                 Tool Assembly With Universal Coupling 
               
               
                   
                   
                 For Various Tools, For 
               
               
                   
                   
                 Work On Underground Pipes 
               
               
                   
               
             
          
         
       
     
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention satisfies the needs discussed above. The present invention is generally directed toward a fitting and method of use which allows for tapping an underground pipe through a keyhole excavation which creates a minimum amount of disturbance to the earth&#39;s surface while also providing a welded connection and seal between the fitting and the pipe. 
         [0008]    The fitting of the present invention uses a weld material which is placed between the fitting and the pipe. This weld material can then be activated from the earth&#39;s surface by applying an electrical charge across the fitting, weld material and pipe. The method for using the apparatus is to dig a keyhole excavation from the earth&#39;s surface to a depth sufficient to expose the pipe being tapped. The fitting is then placed on the pipe with the weld material captured between the fitting and the pipe. A power lead is attached to the fitting and a ground lead is attached to the pipe. An electrical charge is then applied to the power lead. This charge goes through the fitting, weld material and pipe and into the ground lead. Once the weld material has been activated it physically and sealably holds the fitting in place. 
         [0009]    Further objects and features of the present invention will be apparent to those skilled in the art upon reference to the accompanying drawings and upon reading the following description of the preferred embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Preferred embodiments of the invention will now be described in further detail. Other features, aspects, and advantages of the present invention will become better understood with regard to the following detailed description, appended claims, and accompanying drawings (which are not to scale) where: 
           [0011]      FIG. 1  is a cross-sectional view of an excavation showing the prior art fitting in place on an underground pipe. 
           [0012]      FIG. 2  is a cross-sectional view of an excavation showing an embodiment of the fitting of the present invention in place on an underground pipe. 
           [0013]      FIG. 3  is a cross-sectional view illustrating one embodiment of the layout of the insulators, weld material and fittings on a pipe. 
           [0014]      FIG. 4  is a second embodiment of the layout of the insulators and weld material between the fitting and pipe. 
           [0015]      FIG. 5  is an exploded cross-sectional view of a second embodiment of the fitting of the present invention. 
           [0016]      FIG. 6  is an end view of a second embodiment of the present invention mounted on a pipe. 
           [0017]      FIG. 7  is a side view of a second embodiment of the fitting of the present invention mounted on a pipe. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    For explaining the present invention in detail it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of the parts illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein are for the purpose of description and not of limitation. 
         [0019]    Elements shown by the drawings are identified by the following numbers: 
         [0000]    
       
         
               
               
             
           
               
                   
               
             
             
               
                 20 
                 Prior art fitting 
               
               
                 22 
                 Branch fitting 
               
               
                 24 
                 Pipe 
               
               
                 26 
                 First portion 
               
               
                 28 
                 Second portion 
               
               
                 30 
                 Bolts 
               
               
                 32 
                 Elastomeric seals 
               
               
                 34 
                 Keyhole excavation 
               
               
                 36 
                 Surface of earth 
               
               
                 50 
                 Fitting 
               
               
                 52 
                 Branch fitting 
               
               
                 54 
                 Pipe 
               
               
                 56 
                 First portion 
               
               
                 58 
                 Second portion 
               
               
                 60 
                 Weld material 
               
               
                 62 
                 Keyhole excavation 
               
               
                 64 
                 Excavation depth 
               
               
                 66 
                 Bottom (of excavation) 
               
               
                 68 
                 Top (of excavation) 
               
               
                 70 
                 Length of fitting 
               
               
                 72 
                 Insulators 
               
               
                 74 
                 Power lead 
               
               
                 76 
                 Hole 
               
               
                 78 
                 Ground lead 
               
               
                 80 
                 Plug 
               
               
                 82 
                 Hole 
               
               
                 84 
                 Earth&#39;s surface 
               
               
                 90 
                 Fitting 
               
               
                 92 
                 Tubular portion 
               
               
                 94 
                 Saddle-shaped contour cut 
               
               
                 96 
                 Weld material 
               
               
                 98 
                 Plug 
               
               
                 100 
                 Pipe 
               
               
                   
               
             
          
         
       
     
         [0020]    Referring to  FIG. 1 , a prior art fitting  20  is used for attaching a branch outlet  22  to an underground pipeline or pipe  24 . The prior art fitting  20  has a first portion  26  and a second portion  28  held together by a plurality of bolts  30 . The second portion  28  also has a branch outlet  22 . The elastomeric seals  32  are located on the underside of the first and second portions  26 ,  28  of the prior art fitting  20  and are shown in dashed lines. 
         [0021]    In using the prior art fitting  20 , a keyhole excavation  34  is dug from the surface of the earth  36  exposing the pipe  24 . The size of the excavation  34  is depending upon the size of pipe  24  being tapped and to a certain extent, the depth of the pipe  24 . The excavation  34  must be deep enough to expose the bottom side of the pipe  24  so the first portion  26  of the fitting  20  can be placed underneath the pipe  24 . The second portion  28  of the fitting  20  is then placed on the top of the pipe  24 . A plurality of bolts  30  are used to secure the first and second portions  26  and  28  to one another. As the bolts  30  are tightened, the elastomeric seals  32  are compressed between the underside of the first and second portions  26  and  28  of the fitting  20  and the pipe  24 . This provides a seal between the first and second portions  26  and  28  of the fitting  20  and the pipe  24 . Once the fitting  20  is securely in place on the pipe  24 , the pipe  24  can be hot tapped so that a second pipe can be attached to the branch fitting  22  and provide an outlet for the gas or liquid flowing through the pipe  24 . 
         [0022]    Turning to  FIG. 2 , the fitting  50  of the present invention provides a branch fitting  52  for tapping into a pipe  54 . The fitting  50  also has a first portion  56  and a second portion  58 . The first and second portions  56  and  58  are secured and sealed to one another and to the pipe  54  by weld material  60 . The fitting  50  and pipe  54  are shown at the bottom of a keyhole excavation  62 . The depth  64  of the excavation  62  is dependent upon the depth of the pipe  54 . For the embodiment shown in  FIG. 2 , the excavation  62  must be sufficiently deep to provide enough clearance between the pipe  54  and the bottom of the excavation  66  to allow for the first portion  56  of the fitting  50  to be placed on the pipe  54 . The width  68  of the excavation  62  is dependent upon the length  70  of the fitting  50 . The length  70  of the fitting  50  in turn is a function of the diameter of the pipe  54 . 
         [0023]      FIGS. 3 and 4  show two variations of the detail of the weld material  60  once it is put in place. Turning now to  FIG. 3 , the weld material  60  is disposed along the edges of the fitting  50 . Insulators  72  electrically isolate the fitting  50  from the pipe  54 . A power lead  74  passes through a hole  76  in the fitting  50  and is attached to the weld material  60 . A ground lead  78  is attached to the pipe  54 . 
         [0024]    Turning now to  FIG. 4  which shows another embodiment of the detailed joint layout used with the present invention. Here again the fitting  50  and the pipe  54  are electrically isolated from one another by insulators  72 . The weld material  60  extends along the outer edge of the fitting  50  with a triangular cross-section. The power lead  74  is attached to a plug  80  which is then secured to a hole  82  in the fitting  50 . The ground lead  78  is attached to the pipe  54 . 
         [0025]    The method of the present invention involves digging a keyhole excavation  62  extending from the earth&#39;s surface  84  to an excavation depth  64  to expose a pipe  54 . The depth  64  of the excavation  62  should be sufficient to provide clearance between the bottom  66  of the excavation  62  and the pipe  54 . The diameter  68  of the excavation should be sufficient to expose enough of the pipe  54  to secure the fitting  50 . The first portion  56  of the fitting  50  is positioned on a lower surface of the pipe  54 . The second portion  56  of the fitting  50  is positioned on an upper surface of the pipe  54  in alignment with the first portion  56 . Welding material  60  is disposed along the edges of the first and second portion  56  and  58  of the fitting  50  such that it is between the fitting  50  and the pipe  54 . If necessary, one or more insulators  72  can be used to provide proper spacing between the portions  56  and  58  of the fitting  50  and the pipe  54 . 
         [0026]    A power lead  74  is electrically connected to the fitting  50  and in turn the weld material  60 . This can be accomplished in several ways included, but not limited to, attaching the power lead  74  through a hole  76  in the fitting  50  and attaching it directly to the weld material  60 . This can also be accomplished by attaching the power lead  74  to a plug  80  which is seated in a hole  82  in the fitting  50 . A ground lead  78  is attached to the pipe  54 . The portions  56  and  58  of the fitting  50  is then physically and sealably secured to one another and the pipe  54  by passing an electrical charge through the power lead  74  into the weld material  60  through the pipe  54  and back to the ground lead  78 . The control of the electrical current being done from the surface of the earth  84 . The electrical charge melts the weld material  60  causing it to bond with the fitting  50  and the pipe  54 . Once the fitting  50  has been welded to the pipe  54 , the power lead  74  and ground lead  78  can be removed from the fitting  50  and pipe  54 . The pipe  54  and fitting  50  are then ready to be hot tapped. The hot tap operation from this point on is carried out in the same manner that is commonly practiced in the art today. 
         [0027]    The actual joining of the fitting  50  and the pipe  54  can be accomplished by any one of several welding or braising techniques, including by way of example, shielded metal arc welding, exothermic brazing, thermit welding, electro slag welding and explosive welding. The composition of the weld material  60  can adapted to carry out these different types of welding. 
         [0028]    For the shielded metal arc welding process the weld material  60  shown in the drawings would be similar to the composition of a welding rod. The arc would be initially struck on one point along the path of the weld material  60 . The arc would advance along the path of weld material melting the metal in the weld material  60  and releasing an inert shielding gas until the entire length of weld material  60  had been activated. The melted metal would fuse the fitting  50  and the pipe  54  together. Likewise the weld material  60  could also be a composition that would allow for exothermic brazing, thermit welding, electro slag welding or explosive welding. 
         [0029]      FIGS. 5 ,  6  and  7  show another embodiment of the apparatus of the present invention. The fitting  90  has a tubular portion  92  which terminates on one end with a saddle-shaped contour cut  94 . The contour cut  94  is configured to fit the external surface of a short length of exposed pipe  100 . Weld material  96  extends along the saddle-shaped contour cut  94 . The fitting  90  can also have a removable plug  98  sized to fit inside the tubular portion  92  of the fitting  90 . 
         [0030]    In using this second embodiment of the fitting  90 , it is only necessary to dig an excavation to a depth which exposes the upper surface of the pipe  100  sufficient to position the saddle-shaped contour cut  94  on the pipe  100 . Then in a manner similar to that discussed for the first embodiment of the fitting  50  as shown in  FIGS. 2 through 4 , a power lead is attached either to the fitting  90  or directly to the weld material  96 . A ground lead  78  is attached to the pipe  100 . Prior to activating the weld material  96  using an electrical charge, the plug  98  is placed in the interior of the tubular portion  92  of the fitting  90 . The plug  98  prevents weld material  96  from flowing into the interior of the tubular portion  92 . 
         [0031]    With the plug  98  in place, the weld material  96  is activated using an electrical charge applied from the power lead  74  with the charge passing through the weld material  96  activating it. The weld material  96  physically and sealably secures the fitting  90  to the pipe  100 . The electrical charge then passes into the ground lead  78 . Once the power and ground leads  76  and  78  are removed from the fitting  90  and pipe  100 , they are ready for hot tapping. Here again the hot tapping is carried out in the method well known in the art. 
         [0032]    The fitting  90  can also be used without the plug  98  in place by activating the weld material  96  in the same manner as when the fitting  90  is used with the plug  98 . When the fitting  90  is used without a plug  98  some of the weld material  96  will end up in the interior of the tubular portion  92 . The weld material  96  that works its way into the interior of the tubular portion  92  and might affect performance will be removed during hot tapping. 
         [0033]    The weld material  96  shown in  FIGS. 5 ,  6  and  7  can be the same composition as any of the those discussed for the embodiment of the present invention shown in  FIGS. 2 ,  3  and  4 . 
         [0034]    While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claims, including the full range of equivalency to which each element thereof is entitled.