Abstract:
A hot tapping tool having a stationary tubular member threadedly engaged to a movable tubular member adapted for rotational and axial movement with respect to the stationary member with said movable tubular member operably connected to a shaft having cutter head and causing said shaft to move axially toward and away from a pipe line to be cut.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to tools and apparatus for cutting into existing lines carrying fluids such as gas or water under pressure for the purpose of adding additional lines to carry such fluids. 
     In a typical fluid transport system, such as the system supplying water to an average neighborhood, a main water line is buried underground. Branch lines draw water from this main line and deliver water to homes through out the neighborhood. When a new home or other facility is constructed in the neighborhood, it is necessary to connect (or “tap”) the new branch line into the main line. It is imperative that the connection be made without disrupting water service to the other existing homes in the neighborhood. Such a connection under pressure is called a “hot tap” or “live tap”. 
     There are various techniques and instruments that may be used to accomplish the hot tapping of a main line. One example may be found in U.S. Pat. No. 4,902,174 that issued on Feb. 20, 1990 and is assigned to Cliffside Utility Contractors Ltd. As described in the patent, the first step is to secure a “saddle” to the pipe. The saddle is a device that surrounds the pipe and provides a recessed area containing a seal which is flat or otherwise matches the curvature of the pipe. The saddle typically has a threaded collar projecting away from the pipe at the location of the seal, as well as an opening such that a cutting device can pass through the collar to cut into the pipe. A valve device is mounted to the saddle and the hot tapping device mounted to the valve device. Once the cut has been made into the pipe, the hot tapping device is withdrawn and the valve is closed. The device then can be removed, the branch line attached to the valve device, and the valve opened placing the branch line in fluid communication with the main line. 
     One problem associated with the prior art is the buildup of fluid which has “leaked” into the interior of the tool during the cutting operation. Additionally, it has been noted that the cutting operation often leaves undesired residue within the main pipe itself. It is therefore a paramount object of the present invention to provide for a hot tapping tool that is easy to operate and has few moving parts, minimizes and prevents escaping of fluids from the line being cut during the cutting operations, and to minimize or other wise reduce problems caused by cutting debris that is frequently left following a cutting operation in the pipe line itself. This and other objects of the present invention that will become apparent upon a reading of the detailed description with the appended drawings are addressed by the present invention as described below. 
     SUMMARY OF THE INVENTION 
     The present invention involves an improvement to a hot tapping tool adapted to be secured to and cutting into a pipe line carrying a fluid under pressure. The tool generally includes a housing, a shaft supported at spaced locations for rotation and axial movement within the housing, and a cutting device secured to one end of the shaft for cutting into the pressurized pipe line. The tool has a first fluid sealing member sealing an upper end of the housing against external leakage of fluid entering the tool during the cutting operation of the pressurized pipe and a second fluid sealing member sealing a lower end of the housing to minimize entrance of fluid into the tool during cutting of the pressurized pipe line. The tool is further provided with a pressure relief valve for allowing fluid under pressure within the housing to be released to the atmosphere. Still another important aspect of the present invention involves element for retaining a portion of the pressurized pipe cut from the pipe line by the device upon retraction of the device from the pipe line. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a hot tapping tool in accordance with the present invention; 
     FIG. 2 is a side view of a hot tapping tool clamped to a pipe line (shown in section) carrying a fluid under pressure; 
     FIG. 3 is a side cross-sectional view of the hot tapping tool of FIG. 2 with the cutting device poised to cut into the pipe line; 
     FIG. 3A is an enlarged portion of FIG. 3 showing a connection which engages the tool shaft to the tool driving member; 
     FIG. 3B is an enlarged portion of FIG. 3 showing the connection of the hot tapping tool and valve assembly; 
     FIG. 3C is an enlarged portion of FIG. 3 showing the connection of the valve assembly to a collar assembly positioned on and clamped to the pipe line to be cut; 
     FIG. 4 is a side cross-sectional view of the hot tapping tool of FIG. 2 with cutting device in an extended position following the cutting operations; 
     FIG. 5 is a sectional cross-sectional view of a portion of the hot tapping tool showing the cutting device in a retracted position following a cutting operation; 
     FIG. 6 is an enlarged side view of the cutting device illustrating a drill bit and a cutting saw; 
     FIG. 7 is a side view similar to FIG. 6 with the cutting saw shown in side section to illustrate the mounting to the drill bit; and 
     FIG. 8 is a view similar to FIG. 6 depicting a cutting piece or coupon attached to the cutting device following a cutting operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The major components of the present invention are illustrated by the views provided in FIGS. 1-3 in which a hot tapping tool is depicted generally by the character numeral  10  and comprises an externally threaded tube  12 , an internally threaded tube  14 , a shaft  16 , and a cutter assembly  18 . As best seen in FIG. 3, the tube  12  threadedly engages threaded tube  14  along a portion of its length while the lower end of shaft  16  is removably secured to cutter assembly  18 . In FIGS. 2 and 3, the hot tapping tool  10  is illustrated as being secured to a valve assembly  20  and a clamping assembly  22 . 
     A manually operated drive wheel  24  is removably secured or clamped to a selected position along the outer periphery of the tube  14  by a pair of set screws  26 ,  28  (seen in FIG.  1 ). An annularly shaped flanged collar clamp  30  serves to operably connect the shaft  16  to the tube  14  as perhaps best illustrated by the sectional view of FIG. 3 by a collar  30  clamped to the shaft  16  by a pair of bolts  32 ,  34  and engaging the end of the tube  14  by the paired upper and lower flanges  36 ,  38 . Rotation of the drive wheel  24  then rotates the tube  14  about tube  12 , causing tube  14  to move axially up and down tube  12  while simultaneously imparting the same rotation and axial movement to the shaft  16 . As is illustrated in the expanded sectional view of FIG. 3A, the collar  30  is additionally provided with groove to accept an O-ring  40  that provides a seal against the leakage of any fluid that may enter into the internal volume  42  defined by the various components of the tool  10 . When desired, the build up of fluid pressure within the volume  42  may be manually vented by depression of the release valve  44 . A grease fitting  46  permits lubrication of the moving parts as desired. 
     In some instances it may be desirable to rotate shaft  16  directly. This can be done by hand or through the use of an electric motor coupled to the shaft  16 . One mechanism for accomplishing this by hand is perhaps best seen in FIGS. 1 and 4. A coupling member  50  has a pair of bores  50   a  and  50   b  are keyed, respectively to the shaft  48   a  of the T-handle  48  and the upper end of the shaft  16 . The coupling member could be secured by a pair of set screws (not shown) allowing the handle  48  and coupling member  50  to be easily removed and replaced when necessary. Alternatively, the shaft of the T-handle  48  may be provided with a bore that receives the upper end of shaft  16 , thus eliminating the need for a coupling member  50 . 
     The lower end of tube  12  may be tapered and fitted with additional threads  54  that serve to engage an upper internally threaded and tapered boss  58  of a valve adapter  56 . (On small threaded valves, it may not be necessary to use the threaded valve adapter  56 .) The lower end of tube  12  is also provided with a shaft  16  positioning member  60  that has a groove for receiving an O-ring  62  to minimize entrance of fluid into the internal volume  42  of the tool  10  when engaging in a pressurized pipe cutting operation. As best seen in FIG. 6, the lower end of shaft  16  terminates in a bore adapted to receive the shaft  64  of the cutter assembly  18 . A pair of set screws  66 ,  68  secure the shaft  64  within the bore of shaft  16 . The cutter assembly  18  comprises a cutter saw  70  fixed to shaft  64  and a bit  72  provided with pilot drill  74  at the end thereof and self tapping threads  76 . 
     Reference is made to FIG. 3 in which the valve adapter  56  (seen only in FIG. 1) is shown seated within and bolted or appropriately secured to a valve seat  78  of the valve assembly  20 . The valve seat  78  is provided with upper and lower annular flange seats  80  and  82 . Upper flange seat  80  is illustrated as being bolted to flange  57  of the valve adapter  56 . The valve  84  is then appropriately fixed to the valve seat  78  so that its bore that receives shaft  16  can be closed by manual manipulation of handle  86  when the shaft  16  and cutter assembly  18  are completely withdrawn. The lower flange seat  82  is adapted to be bolted or otherwise secured to flanged saddle or clamping assembly  22 . In FIGS. 2 and 3, the clamping assembly  22  is depicted as being clamped about a pipe line  88  using a pair of collars  90  and  92  that are bolted together so that upper collar is in an essentially fluid tight relationship about line  88 . Collar  90  is further provided with a cylindrical member  93  with a bore and an annular lip flange  94  that is positioned against and bolted to the lower flange seat  82  of the valve seat  78 . 
     In operation, the tool  10  is positioned as illustrated in FIG. 3 as being screwed into the valve adapter  78  which in turn is bolted to the valve assembly  20  that is itself secured to the clamping assembly  22  clamped about pipe line  88 . The valve  84  must be in an open state with the valve element  84 a retracted so as to completely open the bore of the valve adapter for the passage of the distal end of the shaft  16  and attached cutter assembly  18 . In FIG. 3, the cutter assembly is illustrated as being poised to cut into pipe line  88 . Because tube  12  is fixed with respect to the line  88 , rotation of the handle  24  will cause tube  14 , and thus shaft  16  and cutter assembly  18 , to rotate about and move axially toward pipe line  88 . Initially, the pilot drill  74  and then the self tapping threads  76  penetrate the walls of the pipe line  88 . Finally the cutting saw  70  cuts a predetermined area out of the pipe line  88 . The seal provided by O-ring  62  prevents significant escape of the fluid carried by the pipe line  88 . FIG. 4 illustrates the location of the cutter assembly at this point in the operation. As is clearly shown in FIGS. 5,  6 , and  7 , the cutter assembly  18  also has a drill component or bit  72  secured to the end of the shaft and extending beyond the cutter saw  70 . The bit  72  terminates into the pilot drill  74  with some intermediately positioned self tapping threads  76 . As the shaft  64  rotates and moves toward the pipe line, the pilot drill  74  and the threads  76  being essentially co-axial with said shaft penetrate a mid-point of the area (coupon) of the pipe to be cut by the cutter saw  70 . From FIG. 8, it may clearly be seen that the coupon  96  is held between the self tapping threads  76  and the cutter head  70  when the shaft  64  is withdrawn from the pipe line. While the above is preferred, other cutting members could be used such as a standard hole saw when desired. 
     Reversing the rotation of the drive wheel retracts the shaft  16 , cutter assembly  18 , and also the coupon  96 . The retraction operation continues until the cutter assembly  18  is located above the opening in the valve adapter  78  receiving the valve element  85 . The valve handle is then manually turned to close the valve sending the element  85  to completely close the bore in the valve adapter  78 . This state of the operation is shown in FIG.  5 . At this point, the tool  10  may be completely removed from the valve adapter  78  and the secondary pipe line secured in its place. Although the amount of pressurized fluid that may have leaked into the volume  42  through the seal of O-ring  62  is likely to be minimal, any such fluid can easily be removed by depressing valve  44  and equilibrating the internal pressure to atmospheric pressure. It is understood that various types of valves could be used including, for example, screw type bleeder valves as employed on brake calipers for automobiles. 
     In light of the discussion above, it should be appreciated that the present invention addresses the objectives set forth above. The tool is simple in operation, provides an effective way of cutting into an existing pressurized line without significant loss of fluids carried by the pressurized line during the cutting operation, and leaves minimal cutting debris within the pipe line when retracted and the cutting operation is completed. Those with ordinary skill in the art upon reading of the disclosure and appended figures will be able to devise other variations and modifications without departing from the spirit and scope of the claims.