Abstract:
A fitting for use with metal tubing includes an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring for making a mechanical connection with an outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Embodiments relate generally to tubing systems and in particular to a fitting for use with a double containment tubing system. Currently, flexible tubing, such as corrugated stainless steel tubing, is used in a number of applications requiring primary and secondary containment. Various plumbing, as well as local and federal, mechanical codes and specifications require that certain types of installations of flexible tubing be protected by a secondary containment system. Tubing containment systems exist in the art to contain fluids if the tubing leaks. One existing double containment tubing system is disclosed in U.S. Pat. No. 7,857,358, the entire contents of which are incorporated herein by reference. 
       SUMMARY 
       [0002]    Embodiments include a fitting for use with metal tubing includes an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring for making a mechanical connection with an outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter. 
         [0003]    Embodiments also include a fitting-tubing assembly including metal tubing having peaks and valleys and an outer jacket; and a fitting secured to the tubing, the fitting including: an adaptor, the adaptor having a longitudinal passage having a longitudinal axis for fluid flow; a body for receiving the tubing, the body positioned opposite the adaptor and aligned with the longitudinal axis; a metal sealing member positioned between the adaptor and the body, the sealing member positioned in a valley of the tubing; a nut positioned opposite the body; a jacket lock ring positioned radially inwardly of a portion of the nut, the jacket lock ring making a mechanical connection with the outer jacket of the tubing; and at least one fastener coupling the nut, body and adapter. 
         [0004]    Other exemplary embodiments are described herein, and encompassed by the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a cross-sectional view of a fitting and tubing in a closed state in an exemplary embodiment. 
           [0006]      FIG. 2  is a cross-sectional view of a fitting in an exemplary embodiment. 
           [0007]      FIG. 3  is an end view of the tubing in an exemplary embodiment. 
           [0008]      FIG. 4  is a perspective, cross-section view of an exemplary fitting and tubing in an open state in an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]      FIG. 1  is a cross-sectional view of a fitting and tubing in a closed state in an exemplary embodiment. The fitting includes an adaptor  1 , a body  2  and a nut  3 . Adaptor  1 , body  2  and a nut  3  all in include a passage therethough formed along a central axis, C. The fitting forms a fluid tight seal on tubing  10  by compressing a portion of the tubing  10  between a sealing surface of sealing member  7  and an adaptor sealing surface of adaptor  1 , as described in further detail herein. 
         [0010]    Adaptor  1  has longitudinal passage along longitudinal axis, C, for fluid flow. Adaptor  1  is generally cylindrical and includes an annular, adaptor sealing surface  20  on an interior portion thereof, radially outward of central axis, C. Adaptor sealing surface  20  has a rounded or radiused surface that contacts tubing  10 . An annular pocket  22  is formed in adaptor  1  radially outwardly of adaptor sealing surface  20 . Pocket  22  receives a rib  28  of body  2 . An annular recess  24  is formed in adaptor  1  radially outwardly of pocket  22 . Recess  22  receives an outer shoulder  32  of body  2 . 
         [0011]    Sealing member  7  is an annular element having a sealing surface  21  that faces adaptor sealing surface  20 . Sealing surface  21  may be planar, and generally frusto-conical. Sealing member  7  may be a formed by split ring washers, a collet or other member. 
         [0012]    Body  2  is generally cylindrical and includes an annular, inner shoulder  26  having a surface perpendicular to central axis, C. Inner shoulder  26  engages one side of sealing member  7 . An annular rib  28  is formed radially outwardly of inner shoulder  26 , parallel to central axis, C. Rib  28  is positioned radially outwardly of sealing member  7 . Rib  28  includes a groove  30  on a radially outward face of rib  28 . Annular groove  30  receives a seal, such as an o-ring, to form a fluid tight seal between body  2  and adaptor  1 . An annular outer shoulder  32  is formed radially outwards of rib  28  and serves to align body  2  with adaptor  1 . Outer shoulder  32  is received in recess  24 . 
         [0013]    Body  2  includes a vent opening  34  that extends through a wall of body  2  to provide fluid communication with the interior of body  2 . Vent opening  34  provides for egress of fluid leaking from piping  10  and/or a port for monitoring of leaking fluid by sensors. Body also includes an annular groove  36  formed on a radially inward face of body  2 , juxtaposed a finger  38  of nut  3 . Groove  36  receives a seal, such as an o-ring, to form a fluid tight seal between body  2  and nut  3 . 
         [0014]    Nut  3  is generally cylindrical and includes an annular finger  38  positioned radially outwardly of a jacket lock ring  4 . Jacket lock ring  4  is positioned on a rear end of the body  2  and engages the outer jacket  11  of tubing  10 , The jacket lock ring  4  is received in an annular recess on the rear end of body  2  where outer jacket  11  enters the fitting. When fully assembled, finger  38  of nut  3  axially slides over jacket lock ring  4  thereby radially compressing jacket lock  4 . A distal end of finger  38  may have an enlarged thickness to aid in driving jacket lock ring  4  into outer jacket  11 . Jacket lock ring  4  includes interior barbs that engage the outer jacket  11 . 
         [0015]    An annular slide ring  6  is positioned between nut  3  and outer jacket  11 . Slide ring  6  is radially inward of finger  38  and abuts jacket lock ring  4 . Slide ring  6  serves to drive jacket lock ring  4  axially towards body  2 . A washer  8  and elastomeric seal  9  may be positioned in an annular groove  40  on an interior surface of nut  3 . Washer  8  and elastomeric seal  9  provide an enhanced seal between the nut  3  and the outer jacket  11 . Slide ring  6  also pushes axially against washer  8  and elastomeric seal  9 , thereby radially compressing elastomeric seal  9  creating a secondary seal on outer jacket  11 . 
         [0016]    As shown in  FIG. 2 , fasteners (e.g., cap screws)  5  slide through opening  50  in nut  3 , opening  52  in body  2  and engage the threads  54  in adaptor  1 . It is understood that threads may be formed on nut  3 , rather than adaptor  1 . As fasteners  5  are tightened, nut  3 , body  2  and adaptor  1  are compressed together. Shoulder  26  of body  2  interacts with a sealing member  7  and adaptor  1  to compress corrugated tubing between the adaptor  1 , body  2  and sealing member  7  to form a liquid tight seal. Adaptor sealing surface  20  is rounded a coacts with sealing surface  21  of sealing member  7 . The use of a rounded adaptor sealing surface  20  and planar sealing surface  21  reduces the load required to create a liquid tight seal. 
         [0017]      FIG. 3  is an end view of the tubing, comprising tubing  10 , inner jacket  12 , and outer jacket  11 . The tubing  10  may be corrugated stainless steel. An inner jacket  12 , manufactured from EFEP, for example, is positioned on the flexible tubing  10 . An exemplary material for inner jacket  12  is a fluoropolymer, available as RP-5000, from Daikin America. This material has the inherent properties of minimal permeation thus providing the secondary containment, this allows fluids (e.g., gas, liquid, etc.) to flow to ends of the outer jacket  11  for venting as described in U.S. Pat. No. 7,857,358. An outer jacket  11  surrounds the inner jacket  12 . An exemplary material for outer jacket  11  is Nylon  12  available as Vestamid X7297, product of Degussa. Contained in the inner diameter of outer jacket  11  are a number of ribs  60  separated by spaces. The ribs  60  are longitudinal and run the length of outer jacket  11 . Ribs  60  in  FIG. 3  are triangular in cross-section, but it is understood that other geometries may be used. In one embodiment, the fluid transported by tubing  10  is gasoline or diesel. In the event that tubing  10  leaks, fluids travel along spaces between ribs for venting through vent opening in body  2 . As described in U.S. Pat. No. 7,004,510, a sensor may be coupled to the vent opening  34  in body  2  to detect fluid leaks and signal such an event. 
         [0018]      FIG. 4  illustrates the fitting in an open or unassembled stated. Tubing  10  includes a number of peaks and valleys. Tubing  10  is cut in a valley and the inner jacket  12  and outer jacket  11  are removed, exposing about  4  peaks of tubing  10 . Nut  3  and body  2  are placed over the outer jacket  11  so that tubing  10  extends beyond body  2 . Sealing member  7  is placed in a first valley at the distal end of tubing  10  and then adaptor  1  is placed over the end of tubing  10 . As fasteners  5  are tightened, body  3 , nut  2  and adaptor  1  are compressed axially along axis, C. The peak of tubing  10  is compressed between adaptor sealing surface  20  and sealing surface  21  of sealing member  7 . This compresses a double layer of tubing  10  between adaptor sealing surface  20  and sealing surface  21  of sealing member  7  for a fluid tight seal. Also, as nut  3  is driven into body  2 , finger  38  drives jacket lock ring  4  into outer jacket  11 . This provides a mechanical attachment between the fitting and the tubing to control axial extension of the fitting under pressure. Also, slide ring  6  applies axial pressure against elastomeric seal  9 , thereby radially compressing elastomeric seal  9  creating a secondary seal on outer jacket  11 . 
         [0019]    The above-described fitting and tubing provides a double containment self-venting feature and a jacket lock. By virtue of the jacket lock  4  and nut  3 , the fitting makes the outer jacket  11  a structural member of the joint, that is, axial extension under pressure is eliminated with this fitting. 
         [0020]    One benefit of the fitting disclosed herein is that the fitting may be reused. Referring to  FIG. 4 , fasteners  5  may be removed from nut  3 , body  2  and adaptor  1  to allow the fitting to be removed from tubing  10 . The fitting may then be re-used with no loss of sealing or containment ability. 
         [0021]    The tubing containment system may be used in a number of applications including direct underground burial, above ground outdoor use, indoor use at elevated pressure for safety and/or other secondary containment and sensing systems for petrochemical lines. 
         [0022]    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.