Abstract:
An embodiment of the invention is a piping system including a fluid impermeable sleeve having a plurality of longitudinal, spaced ribs formed on an interior surface of the sleeve. A fluid carrying tubing is positioned internal to the sleeve. A coupling has a first end and a second end, the first end having interior threads engaging an outer surface of the sleeve. The coupling has a vent opening in fluid communication with the interior of the sleeve.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. provisional patent application 60/458,110 filed Mar. 26, 2003, the entire contents of which are incorporated herein by reference, and claims the benefit of U.S. provisional patent application 60/478,507 filed Jun. 12, 2003, the entire contents of which are incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Tubing containment systems exist in the art to contain fluids if the tubing leaks. One existing tubing containment system is disclosed in U.S. Pat. No. 6,315,003, the entire contents of which are incorporated herein by reference. While well-suited for its intended purpose, the system may be improved.  
         SUMMARY  
         [0003]    An embodiment of the invention is a piping system including a fluid impermeable sleeve having a plurality of longitudinal, spaced ribs formed on an interior surface of the sleeve. A fluid carrying tubing is positioned internal to the sleeve. A coupling has a first end and a second end, the first end having interior threads engaging an outer surface of the sleeve. The coupling has a vent opening in fluid communication with the interior of the sleeve.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is a side view, in partial cross-section, of an exemplary tubing containment system.  
         [0005]    [0005]FIG. 2 is a cross-sectional view taken along line  2 - 2  of FIG. 1.  
         [0006]    [0006]FIG. 3 is a side view of exemplary tubing.  
         [0007]    [0007]FIG. 4 is a side view, in partial cross-section, of another exemplary tubing containment system. 
     
    
     DETAILED DESCRIPTION  
       [0008]    [0008]FIG. 1 is a side view, in partial cross-section, of a tubing containment system  10 . The tubing containment system includes tubing  12  (FIG. 3) which may be contained in a jacket  14 . The tubing  12 , and jacket  14 , are contained within a sleeve  16 . The sleeve  16  may be made from a fluid impermeable material such as polyethylene or other suitable polymers that allow fluids (e.g., gas, liquid, etc.) to flow to ends of the sleeve  16  for venting. FIG. 2 is a cross section of sleeve  16  showing the inner diameter of sleeve  16  having a number ribs  20  separated by spaces. In one embodiment, the fluid transported by tubing  12  is natural gas. The ribs are longitudinal and run the length of sleeve  16 . Ribs  20  in FIG. 2 are triangular in cross-section, but it is understood that other geometries may be used. In the event that tubing  12  leaks, fluids travel along spaces between ribs  20  for venting through couplings  18 .  
         [0009]    At each end of sleeve  16  is a coupling  18  having a first end  22  that covers the exterior surface of sleeve  16 . A seal  24  (e.g., an o-ring) may be located at first end  22  to prevent fluid from exiting coupling  18  at first end  22 . Coupling  18  includes a shoulder  26  that serves as a stop to limit the insertion depth of sleeve  16  into coupling  18 . Shoulder  26  terminates prior to contacting jacket  14  to provide a passage to vent opening  28 .  
         [0010]    The interior surface of coupling  18  is preferably threaded. The threads engage the outer surface of sleeve  16  to secure coupling  18  to sleeve  16 . Coupling  18  may be made from polyethylene or other polymer. In one embodiment, coupling  18  is made from a harder polymer (i.e., higher durometer) than sleeve  16  to facilitate threading coupling  18  on sleeve  16 . Alternatively, coupling  18  may be metal depending on application.  
         [0011]    One or more vent openings  28  are provided in coupling  18  located toward a second end  30  of coupling  18 . Second end  30  has an inner diameter slightly larger than jacket  14  and a seal  32  (e.g., an o-ring) provides a fluid seal between second end  30  and jacket  14 . The vent openings  28  allow fluid leaked from tubing  12  to escape in a controlled manner through vent opening  28 . A hose or other conduit may be connected to vent opening  28  to divert leaked fluid. A sensor may also be in fluid communication with vent opening  28  to provide automatic detection of leaks in tubing  12 . The jacket  14  of tubing  12  may be perforated or otherwise compromised to facilitate migration of leaked fluid to vent opening  28 .  
         [0012]    The sleeve  16  may be extruded over tubing  12  (whether or not jacket  14  is present) using a die to form ribs  20  on the interior surface of the sleeve  16 . As shown in FIG. 3, the tubing is annular, corrugated tubing, but may be a variety of types of tubing including helically wound tubing. In one embodiment, the tubing  12  is corrugated stainless steel tubing. The jacket  14  may be conductive to dissipate electrical charge.  
         [0013]    [0013]FIG. 4 is a side view, in partial cross-section, of an alternate tubing containment system  40 . Tubing containment system  40  includes tubing  12 , jacket  14  (optional) and sleeve  16  similar to those described above with reference to FIGS. 1-3. A fitting  42  is secured to one end of the tubing  12 . The fitting  42  may be any known fitting such as those disclosed in U.S. Pat. Nos. 5,799,989, 6,079,749, 6,276,728 the contents of which are incorporated herein by reference, with the inclusion of a threaded extension  44  at the end of the fitting that engages the tubing  12 .  
         [0014]    The threaded extension  44  is made of metal (e.g., brass) and engages the inner surface of a transition coupling  46 . The transition coupling  46  is preferably made from fluid impermeable material such as polyethylene or other suitable polymers that contain fluids (e.g., gas, liquid, etc.). The inner diameter of the transition coupling  46  is slightly larger than the outer diameter of the sleeve  16  causing a friction fit between the transition coupling  46  and the sleeve  16 . The threaded extension  44  engages the inner surface of the transition coupling  46  to secure the fitting  42  to the transition coupling  46 . A seal  48  (e.g., o-ring) and a seal  50  (e.g., o-ring) provide a fluid-tight connection between the transition coupling  46  and the fitting  42  and the sleeve  16 , respectively. A vent opening  52  (optionally threaded) provides for egress of fluid and/or monitoring of leaking fluid by automated detection apparatus.  
         [0015]    The tubing containment system  40  operates in a manner similar to tubing system  10 . If a leak occurs in tubing  12 , the fluid is conveyed along the space between tubing  12  and sleeve  16 . The fluid is contained in transition coupling  46  and expelled through vent opening  52 .  
         [0016]    The transition coupling  46  covers the tubing  12  up to fitting  42  and overlaps fitting  42  to eliminate any exposed tubing  12 . The transition coupling  46  and the fitting  42  are preferably reusable.  
         [0017]    The tubing containment systems may be used in a number of applications including direct underground burial, above ground outdoor use, indoor use at elevated pressure for safety and other secondary containment and sensing systems for petrochemical lines.  
         [0018]    While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.