Abstract:
A pipe coupling assembly for double-wall pipe having an interstice between an inner pipe and an outer pipe, which joins the terminal ends of adjacent sections of the double-wall pipe to a fitting element, as a tee or elbow fitting, as well as to a connector tube bypass assembly. The coupling assembly provides fluid communication between the interstices of the adjacent sections of the double-wall pipe and the connector tube bypass assembly but does not permit fluid from the interstices of the pipes to pass through the pipe fitting.

Description:
OVERVIEW  
         [0001]    A pipe coupling and assembly according to the present invention is well suited for use with coaxial pipe systems, such as that disclosed by U.S. Pat. Nos. 5,297,896 and 5,927,762, both to Webb and incorporated herein by reference. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0002]    [0002]FIG. 1 shows a coupling assembly of the present invention in longitudinal cross section.  
         [0003]    [0003]FIG. 2 shows a coupling assembly of the present invention in plan. 
     
    
     DETAILED DESCRIPTION  
       [0004]    [0004]FIG. 1 shows a coupling assembly in longitudinal cross section, generally identified by the numeral  10 . The pipes  20  of the system include an inner tubular member  22 , an outer tubular member  24  and an interstice  26  therebetween. The embodiment of the coupling assembly  10  shown in the Figures comprises two pipe engaging members  30 , which are the same in all material respects. The two pipe engaging members  30 , appearing as mirror images of each other, are shown connected to pipes engaged with a “T” fitting  28 . For purposes of clarity, some elements have been labeled on only one of the two pipe engaging members  30  shown in the Figures.  
         [0005]    A pipe engaging member  30 , preferably metal, is adapted to be secured to the end of a pipe  20 . The pipe engaging member  30  has a proximal end  32  for engaging the pipe, and a distal end  34  for engaging a pipe fitting  28  or second run of pipe. A connecting member is disposed on the distal end  34 , optimally in the form of a threaded locking collar  36  for engaging a corresponding fitting. Alternatively, the connecting member may comprise other coupling means, such as a reducing coupling, straight run of pipe for accepting a coupling, or the like.  
         [0006]    The proximal end  32  of the pipe engaging member  30  comprises a ferrule  38  for engaging the outside surface of the outer tubular member  24  of the pipe  20 . Optimally, the ferrule  38  includes teeth  40  or other suitable means disposed on its inside surface for gripping the outside surface of the outer tubular member  24  and forming a fixed engagement therewith. If the engagement between ferrule  38  and the outer tubular member  24  does not form a seal, sealing means (not shown), such as one or more “O” rings may be provided.  
         [0007]    The proximal end  32  further includes an insertion length  42  for engaging the inside surface of the inner tubular member  22 . The outside surface of the insertion length  42  is preferably provided with teeth  44  or other suitable means for engaging the inside surface of the inner tubular member  22  and forming a fixed engagement therewith. If the engagement between the insertion length  42  and the inner tubular member  22  does not form a seal, sealing means (not shown), such as one or more “O” rings may be provided.  
         [0008]    When the pipe engaging member  30  is installed with a pipe and engaged with a fitting  28  (as described below) or second run of pipe, fluid within the inner tubular member  22  is in communication with the interior  46  of the pipe engaging member  30 , as well as the interior volume  48  of the fitting.  
         [0009]    The pipe engaging member  30  is provided with a groove  50  disposed between the ferrule  38  and the insertion length  42 , preferably between the end of the teeth  40 ,  44  and a region  52  at which the ferrule  38  and the insertion length  42  converge. The groove  50  is in fluid communication with the interstice  26  of pipe  20 . A test port  56  is disposed adjacent region  52  in fluid communication with groove  50  and, thus, with interstice  26 . The test port  56  is preferably threaded to allow engagement of a relatively small pipe fitting or elbow  58 . Pipe fitting or elbow  58  is provided with a tube  60 , shown cut away in FIG. 1. Tube  60  connects the two elbows  58  of each coupling insert  30 . Thus, fluid within the two interstices  26  of two pipes  20  is in communication via two grooves  50 , test ports  56 , elbows  58  and tube  60 .  
         [0010]    As noted above, a connecting member, preferably a threaded locking collar  36 , is disposed on the distal end  34  of the pipe engaging member  30 . The locking collar  36  is free to rotate about the longitudinal axis of the pipe engaging member  30 ; but, the locking collar  36  is restricted from moving longitudinally past the distal end  34  of the pipe engaging member  30  by a lip  62 . Thus, the locking collar  36  is free to engage corresponding threads on a fitting  28 . An extended groove  64  is provided adjacent the region  52  (opposite groove  50 , and between region  52  and the lip  62 ). The extended groove  64  allows the locking collar  36 , to be unscrewed from a threaded engagement with the fitting  28 . In embodiments of the inventions employing an alternative connecting member, the extended groove  62  may be modified or omitted as necessary.  
         [0011]    [0011]FIG. 2 shows a side view of the assembly of FIG. 1. The “T” fitting  28  is engaged with two pipes  20  via two pipe engaging members  30 . The proximal end  32  of each pipe engaging member  30  comprises a ferrule  38  and an insertion length (element  42  in FIG. 1), of which only the ferrule  38  is visible in FIG. 2. The distal end  34  comprises a connecting member, preferably a locking collar  36 .  
         [0012]    An elbow  58  is engaged with a test port (element  56  in FIG. 1) of each pipe engaging member  30 , the test port being disposed adjacent a region  52  where the ferrule  38  and the insertion length converge. The test ports, and, in turn, the elbows  58  are in fluid communication with the respective interstices of pipes  20  as shown in FIG. 1 and described above with regard thereto. The two elbows  58  are connected to one another and in fluid communication via tube  60 .  
         [0013]    Thus, the coupling assembly  10  provides fluid communication between the interstices  26  of two pipes  20  engaged to opposite sides of a fitting, such as a “T” fitting, while keeping the fluid therein isolated from the interior  46  of the coupling, as well as the interior volume  48  of the fitting. The invention provides said communication without the need for unwanted cutting of the pipe or provision of adapters required by former attempts to achieve similar goals.