Abstract:
A tapping assembly implements a unitary saddle fitting design to enable the formation of a branch connection with a polymeric flowable material transmission line. The tapping assembly includes a unitary saddle fitting and a set of cutting elements operative to create openings in a structural wall of the transmission line and thereby form a fluid communication pathway from the transmission line through the saddle fitting and onto a service line connected with the tapping assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    With the modernization of fluid and gas transmission networks, conduit mains for delivering to homes and businesses are increasingly more likely to be fabricated from polymeric materials, such as polyvinyl chloride (PVC) and other plastic-type materials. These utility mains are typically routed adjacent to or beneath streets in horizontally oriented trenches to convey pressurized natural gas or water from a main supply source to various locations where service line conduits tap into the main and draw gas or water therefrom. As a rule of thumb for supplying natural gas, service lines typically range from one-half inch to two inches in diameter depending on the level or service needed for the particular line, although service lines can also be much larger. Each service line may serve a single building structure or a group of buildings, such as a small office complex or a subdivision. Polymeric mains are advantageous due to the fact that service line connections with such mains are substantially easier than with a traditional cast iron conduit main. Additionally, polymeric materials are electrically insulative, thus providing a more stable medium in which to convey an explosive gas, and also are relatively easy to handle during subterranean installation and later repair. 
         [0004]    Sidewall tapping tees and full flow tees have been developed to create a junction or branch connection between a polymeric main and a service line. Sidewall tapping tees are mounted on the exterior surface of the main, while full flow tees are actually place in-line where a section of the main is removed. In a conventional design, a sidewall tapping tee includes a base for mounting with a cylindrical main in a circumscribing fashion, a riser portion extending upwardly from the base for housing a threaded cutting member and flow passageway, and an arm extending arm from the riser portion to provide a branch connection point for a service line extending to a building. The cutter is typically threadingly received within the riser portion and has a top face with a recess for accepting a hex wrench or other tool, and a lower annular cutting edge. By using the tool to drive rotation of the cutter, the cutting edge moves downwardly through the flow passageway and eventually through an opening in the base to engage with and cut in a radially advancing direction through a cylindrical wall of the main on which the tapping tee is mounted. The cutter is retracted back through the base opening and up through the flow passageway a sufficient amount as to expose a service passageway through the laterally extending arm. A flow path is thereby formed to allow gas or water in the main to be conveyed through the base opening and through the flow passageway to the service passageway and onto a service line secured with the laterally extending arm and extending perpendicularly to the main. One advantage of a sidewall tapping tee when tapping into a gas transmission main is that the flow of gas through the main does not have to be shut off during the tee installation process. With a full flow tee, the gas or water main must actually be sectioned or cut through to remove a portion of the main that is replaced by the tee, which requires, in some cases, an interruption of service flow to customers along the main. The full flow tee includes outlets aligned longitudinally with the main as well as a perpendicularly extending service arm for connection with a branch line. 
         [0005]    Although sidewall tapping tees and full flow tees provide a means for creating a junction for a polymeric gas or water main, there are a number of drawbacks with conventional designs and installation processes for each type of tee. For instance, with sidewall taping tees of the aforementioned design, because the lateral arm must extend perpendicularly from the riser portion, and the lateral arm extends horizontally to couple with a horizontally-oriented buried branch line, the riser portion necessarily extends vertically from the main to which the taping tee is mounted. This is problematic because it significantly increases the risk of damage to the taping tee if future excavation work is done in the vicinity of the main conduit. Contractors and other third party workers can typically find out how far down below the ground surface a gas or water main is buried from a utility company, but it is difficult to know at what particular point along a section of a subterranean conduit main a taping tee is attached and how far above the main the tee rises vertically. For instance, a worker will often begin to unearth a section of a main with earth moving equipment to within a few inches of a depth at which the conduit is reported to be buried, and then fully unearth the main using hand shovels or other tools to avoid damaging the main. However, if the worker does not take into account that a sidewall tapping tee provides a 6 inch or more rise above the buried main, there is a high probability that the tee could be damaged during the excavation process. Traditional sidewall tapping tee designs are also limited in the size or diameter of the branch connection that can be made based on the diameter of the main conduit. More specifically, if the ratio of the diameter of the cutter (and thus the opening cut radially into the main) to the overall main diameter is sufficiently large, the structural integrity of the main could be compromised during operation. It may be desired, however, to create a relatively large opening in the main to achieve a flow through the branch connection sufficient to meet the needs of the customers along the service line. As one example, it can difficult or even impossible to form a 4 or 6 inch diameter opening for a branch connection with only a 6 inch outside diameter main. Full flow tees, in contrast, provide a wider range of options for branch connection openings from mains of various sizes. Still though, full flow tees require depressurization of a section of a main where the full flow tee is to be installed. Even if service flow interruption to other customers can be avoided, such as in the case of a pressurization feed in the main conduit from both directions, the equipment and labor necessary to squeeze off a main, and to actually cut out and remove a section of the main for installation of the tee, can be substantial. Therefore, existing devices have failed to provide a reliable and simple solution for creating branch connections off a transmission main where the future risk in damaging the junction formed remains low. 
       SUMMARY OF THE INVENTION 
       [0006]    A tapping assembly of the present invention enables the formation of a branch connection with a polymeric flowable material transmission line, such as a gas or water conduit main. The tapping assembly includes a unitary saddle fitting and a set of cutting elements operative to create openings in a structural wall of the transmission line and thereby form a fluid communication pathway from the transmission line through the saddle fitting and onto a service line connected with the tapping assembly. The unitary saddle fitting has a base portion formed with a set of intake ports, as well as a manifold extending outwardly from the base portion which is characterized by a primary passageway and a set of secondary passageways. The primary passageway extends from the set of intake ports to a branch outlet and each secondary passageway is aligned with one of the intake ports and extends from the primary passageway to a tapping outlet. Additionally, each secondary passageway has a threaded portion for receiving matching threads on a cutting element to enable each cutting element to be driven towards a cutting surface of the transmission line. 
         [0007]    In use, the tapping assembly is first coupled to the structural wall of the transmission line by fitting the base portion onto the wall in at least a partially circumscribing fashion. Each cutting element is rotationally driven by a tool engaged therewith through the respective secondary passageway and through the respective intake port to contact the structural wall and cut therethrough to form a resulting cutout in the transmission line wall. The cutting element is then retracted through rotation in the opposite direction to move out of the cutout in the transmission line wall and the respective intake port to reveal the fluid communication pathway through the manifold of the saddle fitting. Sealing caps may be secured onto tapping stems of the manifold to seal off each tapping outlet after the cutting process is completed so that the flow pathway through the tapping assembly extends from the intake ports to the branch outlet for delivering the flowable material to a service line coupled to the assembly. 
         [0008]    The tapping assembly design of the present invention, including a unitary fitting having multiple secondary passageways in which cutting elements travel, allows for the use of smaller diameter cutting elements in creating a given total flow path to a service line from the transmission line. With a traditional single cutter sidewall tapping tee, sufficient fluid flow through the tee can sometimes only be obtained when the diameter of the cutting element approaches the diameter of the structural wall of the transmission line, which can compromise the structural integrity of the transmission line. Additionally, by positioning the tapping outlets and the branch outlet generally in the same plane, the tapping assembly provides a low-profile design extending substantially laterally from a horizontally extending transmission line. This low-profile enables the assembly to minimize the structure that rises above the transmission line, reducing the chance that equipment used to unearth the line from above would damage the assembly. 
         [0009]    Additional advantages and features of the invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. 
     
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]    In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are employed to indicate like parts in the various views: 
           [0011]      FIG. 1  is a top plan view of one embodiment of a tapping assembly of the present invention installed on a section of a transmission line; 
           [0012]      FIG. 2  is partially sectioned view of the tapping assembly of  FIG. 1 , illustrating the flowpath from the transmission line through a manifold of the tapping assembly; 
           [0013]      FIG. 3  is an exploded view of the tapping assembly, partially in section, taken along line section line  4 - 4  of  FIG. 1 ; 
           [0014]      FIG. 4  is a sectional view of the tapping assembly taken along line  4 - 4  of  FIG. 1 , depicting the cutting element in a position for engagement with a wall of the transmission line; and 
           [0015]      FIG. 5  is a side elevational view of the tapping assembly coupled onto a section of the transmission line in a subterranean application. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring now in more detail to the drawing figures, and initially to  FIG. 1 , a tapping assembly of the present invention designated by reference numeral  10  is shown in use on a transmission line  100 , such as a natural gas or water conduit main. The tapping assembly  10  provides a junction between the transmission line  100  and a service or branch line (not shown) connected with a branch outlet  12  of the tapping assembly  10 , as can be seen with further clarity in  FIG. 2 . The tapping assembly generally includes a unitary saddle fitting  14  and a coupling device  16  for coupling or initially securing the saddle fitting  14  onto a section of a structural wall  102  of the transmission line  100  prior to engaging in a tapping sequence on the transmission line  100 . 
         [0017]    For instance, as illustrated in  FIG. 1 , and with additional reference to  FIG. 3 , one embodiment of the tapping assembly  10  includes an adjustable split collar  18  serving as the coupling device  16 . The collar  18  is formed by a base  20  of the saddle fitting  14  and a corresponding opposed free collar member  22 . Both the saddle fitting base  20  and the free collar member  22  have generally cylindrically-shaped mating surfaces  24  and  26 , respectively, to achieve circumferential mating with an outside surface  104  of the structural wall  102  of the transmission line  100 . The saddle fitting base  20  and the free collar member  22  also each have outwardly extending mounting flanges  28  and  30 , respectively, through which apertures  32  extend for receiving a set of fasteners  34 . With the saddle fitting  14  and the free collar member  22  separated, the base  20  of the saddle fitting  14  and the free collar member  22  are extended over a chosen section of the transmission line structural wall  102  and secured together onto the outside surface  104  of the wall  102  with the fasteners  34 . More specifically, the apertures  32  of the mounting flanges  28  and  30  are aligned so that the fasteners  34  can couple the flanges  28  and  30 , and thus the saddle fitting base  20  and the free collar member  22 , together on the transmission line  100 . In an alternative arrangement, the coupling device  16  may take the form of the saddle fitting base  20  and adjustable strapping material (not shown) circumscribing the transmission line  100  and extending over the saddle fitting base  20  to secure the saddle fitting  14  to the line  100  without the use of a free collar member  22 . Those of skill in the art will appreciate that other means may be implemented to provide initial coupling of the tapping assembly  10  with a section of the transmission line  100 . 
         [0018]    With continued reference to  FIGS. 2 and 3 , the unitary saddle fitting  14  is formed with a manifold  36  extending outwardly from the base  20  to provide a flow pathway leading from the transmission line  100  to a connected service line. The manifold  36  includes a primary passageway  38  and set of secondary passageways  40  disposed on opposed lateral sides of the primary passageway  38 . The primary passageway  38  extends from a set of intake ports  42  formed through the saddle fitting base  20  to the branch outlet  12  where a service line can connect with the tapping assembly  10 . More specifically, the primary passageway  38  is defined by opposed lateral conduit sections  46  that merge to form a main conduit section  48  moving downstream towards the branch outlet  12 . Each secondary passageway  40  is generally cylindrically shaped and axially aligned with one of the intake ports  42 , extending from one of the lateral conduit sections  46  of the primary passageway  38  to a tapping outlet  50 . The branch outlet  12  and each tapping outlet  50  are preferably bisected in the same plane, allowing the manifold  36  of the saddle fitting  14  to maintain a low-profile that extends essentially in a single lateral direction to connect with a horizontally extending service line transversely arranged with respect to the transmission line  100 . 
         [0019]    Each secondary passageway  40  is configured for receiving therein a cutting element  52  that may be rotationally driven towards the respective intake port  42  to eventually reach the transmission line structural wall  102  when the tapping assembly  10  is coupled to the transmission line  100 . In this way, the secondary passageways  40  largely serve to guide the movement of cutting elements  52  towards the respective intake ports  42  to generate radially-extending cutouts  106  in the structural wall  102  of the transmission line  100 , while the primary passageway  38  functions as the continuous flow pathway for flowable material (i.e., natural gas, water, etc.) from the transmission line  100  through the manifold  36  to an attachment point for a service line at the branch outlet  12 . Specifically, with reference to  FIG. 3  and additional reference to  FIG. 4 , each cutting element  52  has a tool engaging first end  54 , a second opposed end formed as an annular working blade  56 , and threaded body portion  58  therebetween. Additionally, the cutting elements  52  may each have a sealing washer  60 , or o-ring, below the threaded body portion  58  to seal off any pathway between the cutting element  52  and the inner wall  64  forming the secondary passageway  40 . An internal threaded section  66  of the secondary passageway  40  has matching threads with the cutting element body portion  58  to support the rotational movement of the cutting element  52 . The tool engaging first end  54  of the cutting element  52  includes a shaped bore  68  for receiving therein any chosen tool configuration. For instance, in the case of the bore  68  having a hexagonal shape, a hex wrench (or other appropriately shaped tool) can mate and engage with the bore  68  to rotate the cutting element  52  according to the guidance of the threaded body portion  58  interfacing with the threaded section  66  of the secondary passageway  40 . 
         [0020]    As seen in  FIG. 4 , rotation of the cutting element  52  a sufficient amount in a first direction drives the working blade  56  through the respective intake port  42  to engage with the transmission line structural wall  102 . Continued rotation in the same direction forces the working blade  56  through the structural wall  102  at an annular profile, thereby forming the circular cutout  106  in the wall  102 , as illustrated in  FIG. 2 . Thereafter, rotation of the cutting element  52  in an opposed, second direction retracts the working blade  56  through the intake port  42  and back further into the secondary passageway  40 . The flow of gas or water from the transmission line  100  through the cutout  106  and into the manifold  36  of the tapping assembly  10 , represented by arrows F in  FIG. 2 , becomes less inhibited the greater the working blade  56  is retracted out of the respective lateral conduit section  46 . A plug (not shown) of the structural wall cutout  106  is held by a series of grooves  70  within the annular working blade  56  to inhibit the flow of gas or water from the transmission line  100  through a central bore  72  of the cutting element  52  and up the secondary passageway  40 . 
         [0021]    The saddle fitting  14  is preferably shaped around the manifold  36  such that a branch stem  74  establishes the main conduit section  48  of the primary passageway  38  and a set of tapping stems  76  each establishing one of the secondary passageways  40 . In this way, the branch stem  74  terminates at the branch outlet  12  and each tapping stem  76  terminates at one of the tapping outlets  50 . A sealing cap  78  having an internally threaded collar  80  is received by mating threads  82  on the outer surface  84  of each of the tapping stems  76 . The sealing cap  78  serves to seal off the tapping outlets  50  of the set of secondary passageways  40  once the tapping sequence with the cutting elements  52  is complete, ensuring that flow through the manifold  36  is directed from the intake ports  42  through the primary passageway  38  and out through the branch outlet  12 . In an alternative arrangement, the collar  80  of each sealing cap  78  may have external threads for engaging with the internal threaded section  66  of one of the secondary passageways  40  above the respective cutting element  52 , such that the collar  80  is received within the tapping stem  76 . 
         [0022]    After the tapping assembly  10  is initially secured onto a section of the transmission line  100  by the split collar  18 , the region surrounding each intake port  42  on the mating surface  24  of the saddle fitting base  20  needs to be sealed with the outside surface  104  of the transmission line structural wall  102 . This ensures that flow leaving one of the cutouts  106  in the structural wall  102  moves directly into the respective intake port  42  and into the manifold  36  without leaking through any gap between the mating surface  24  of the saddle fitting base  20  and the outside surface  104  of the structural wall  102 . Accordingly, sealing of the mating surface  24  with the outside surface  104  of the transmission line structural wall  102  may be made by various means, such as by the use of a solvent, cement, glues (e.g., PVC glue for a transmission line  100  and saddle fitting  14  formed of PVC), or other arrangements. As one example, a o-ring may be placed within an annular recess (not shown) in the mating surface  24  surrounding each intake port  42  to seal against the outside surface  104  of the structural wall  102 . In still another example, electrofusion may be utilized to seal the mating surface  24  with the structural wall outside surface  104 . With electrofusion, a heating element (not shown) formed by conductive pathway on the mating surface  24  surrounding each intake port  42  causes melt fusion between the surfaces  24  and  104  in the region surrounding the intake port  42 . 
         [0023]    By configuring the primary passageway  38  with opposed lateral conduit sections  46  extending from multiple intake ports  42  to the main conduit section  48 , a flow path is created that avoids significant pressure drops between the cutouts  106  in the transmission line  100  and the branch outlet  12  where a service line connects. As one exemplary configuration, a transmission line  100  having a 2 inch outer diameter may be tapped by the tapping assembly  10  including a pair of cutting elements  52  each having a working blade  56  sized to form a 1 and ⅛ inch cutout  106  in the transmission line  100 . Additionally, the intake ports  42  and the lateral conduit sections  46  of the primary passageway  38  are sized to maintain a diameter at least as large as the cutout  106  diameter, in this case a 1 and ⅛ inch diameter, while the main conduit section  48  has a 2 inch diameter to match the internal diameter of a service line to be coupled with the branch outlet  12 . This configuration serves to minimize pressure drop through the manifold  36  while providing the desired amount of flow to the service line. Those of skill in the art will appreciate, however, that other dimensions may be selected in order to maintain adequate flow through the manifold  36  based on a given diameter of a selected transmission line  100 . In any case, the tapping assembly  10  provides significantly improved flow for a sidewall tapping tee where the diameter of the service line to be connection approaches the diameter of the transmission line. 
         [0024]    With a traditional tapping tee, forming a cutout  106  with a diameter approaching the size of the outer diameter of the transmission line  100 , if even possible, would seriously affect the structural integrity of the transmission line  100  and any bond formed between the mating surface  24  and the outside surface  104  of the structural wall  102 . The tapping tee  10  of the present invention avoids this problem by providing multiple, smaller diameter cutouts  106  and a manifold  36  configured to provide flow to the branch outlet  12  and connected service line that is equivalent to flow that would be realized through one larger cutout  106  if the transmission line  100  had been sized adequately to support such a large cutout. Furthermore, by utilizing a saddle fitting  14  that is unitary in nature, the tapping assembly  10  functioning as a multiple cutter tapping tee can be initially coupled to a transmission line  100  (i.e., prior to sealing or fusing the base  20  with the outside surface  104 ) in essentially one step. In one embodiment, the unitary saddle fitting  14  and free collar member  22  are each formed by molding a polymeric material, such as one or more plastics and the like. The cutting elements  52  may be formed from various materials having a hardness greater than the hardness of the polymeric transmission line  100 . For instance, the cutting elements  52  may be formed from solid brass or other metals. It should also be understood that additional secondary passageways  40  and corresponding cutting elements  52  and intake ports  42  may be provided for each primary passageway  38  and branch outlet  12  in the saddle fitting  14 . 
         [0025]    Turning to  FIG. 5 , the low-profile mounting of the tapping assembly  10  on a subterranean transmission line  100  section is depicted. In this configuration, the manifold  36  extends generally within a plane aligned with the longitudinal axis of the transmission line  100 . Thus, when the transmission line  100  is installed horizontally, the branch stem  74  and tapping stems  76  of the tapping housing  14  are also horizontally oriented and transverse to the longitudinal dimension of the transmission line  100 . With traditional sidewall taping tees, the riser portion housing the cutting element extends well above the top of the transmission line  100  towards the surface S, increasing the likelihood that the taping tee will be damaged by excavation activities. The tapping assembly  10  of the present invention merely has a portion of the split collar  18  (or other coupling device  16 ) disposed above the transmission line  100  when installed, decreasing the likelihood that the buried tapping assembly  10  would be damaged during excavation. 
         [0026]    As can be understood, the tapping assembly  10  of the present invention provides a self-contained unit for creating an adequately sized flow junction between a polymeric transmission line  100  and a service line. The tapping assembly  10  also has a decreased likelihood of being damaged by excavation activities in a subterranean installation as compared to traditional sidewall taping tees. 
         [0027]    Furthermore, since certain changes may be made in the above invention without departing from the scope hereof, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claims are to cover certain generic and specific features described herein.