Patent Publication Number: US-2005120534-A1

Title: Shrouded fluid-conducting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application is a divisional of presently allowed U.S. patent application Ser. No. 10/215,498, filed on Aug. 9, 2002. The entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates generally to fluid-conducting apparatus and more particularly to methods and apparatus for conducting fuel in aircraft.  
     BACKGROUND OF THE INVENTION  
      According to Federal Aviation Administration (FAA) regulations, fuel lines (e.g., manifolds, conduits) that conduct or transport fuel through areas classified by the FAA as “ignition zones” (e.g., pressurized areas) must be shrouded and capable of being drained. The applicable sections of the FAA requirements relative to fuel lines in aircraft ignition zones for transport category airplanes are contained in 14 C.F.R. Part 25, the pertinent parts of which are set forth below.  
      For example, Section 25.855 states in pertinent part that “for each cargo and baggage compartment not occupied by crew or passengers . . . no compartment may contain any controls, wiring, lines, equipment, or accessories whose damage or failure would affect safe operation, unless those items are protected so that . . . they cannot be damaged by the movement of cargo in the compartment, and . . . their breakage or failure will not create a fire hazard.” Section 25.863 states in pertinent part that “in each area where flammable fluids or vapors might escape by leakage of a fluid system, there must be means to minimize the probability of ignition of the fluids and vapors, and the resultant hazards if ignition does occur.” Section 25.901 states in pertinent part that “for each power plant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination of failures will jeopardize the safe operation of the airplane except that the failure of structural elements need not be considered if the probability of such failure is extremely remote.” Section 25.967 states in pertinent part that “each fuel tank must be isolated from personnel compartments by a fumeproof and fuelproof enclosure.” 
      To summarize, the FAA regulations ensure that no single failure will jeopardize safe operation of the aircraft, as would be the case if single-wall fuel manifolds were used in aircraft “ignition zones.” That is, a leak or rupture in a single-wall fuel manifold would allow fuel to enter the “ignition zone”, which could result in catastrophic event were the fuel to ignite or explode.  
      To comply with the FAA shrouded fuel line requirements, several methods have been employed. One method involves the installation of a hose inside a tube. To be compatible with the present aerial refueling manifold which includes a five-inch (5.0″) outside diameter duct, this concept requires the hose to be disposed within a twelve inch (12.0″) outside diameter tube. Due to space limitations aboard aircraft, however, the relatively large outside diameter required for the outer tube has rendered this hose-in-tube concept impracticable.  
      In another effort at least in part to satisfy the FAA shrouded fuel line requirements, an alternative method has involved placing an inner tube in a second tube without any means for supporting the inner tube. Accordingly, the inner tube in this concept is unable to transfer loads to the outer tube and/or to components external thereto and is thus not viable.  
     SUMMARY OF THE INVENTION  
      Accordingly, a need remains for an FAA-compliant device and method for transporting fuel through an aircraft “ignition zone” that is not space or cost prohibitive. Ideally, the device would allow for the transfer of loads from the device to one or more components external to the device.  
      In one form, the present invention provides a shrouded fluid-conducting apparatus that includes at least one outer conduit and at least one inner conduit disposed within the outer conduit. Preferably, the shrouded fluid-conducting apparatus further includes at least one shrouded end fitting disposed at an end of the shrouded fluid-conducting apparatus and at least one support member engaged with the inner and outer conduits. The shrouded end fitting allows the shrouded fluid-conducting apparatus to be engaged with an additional shrouded fluid-conducting apparatus. The support member allows for the transfer of loads from the inner and/or outer conduits to one or more components external to the shrouded fluid-conducting apparatus. Accordingly, the shrouded fluid-conducting apparatus may be used to transport fuel through an aircraft “ignition zone” in an FAA-compliant manner.  
      In another form, the present invention provides a method of manufacturing or making a shrouded fluid-conducting apparatus. Generally, the method comprises the steps of: disposing at least one inner conduit within at least one outer conduit; engaging at least one support member with the inner and outer conduits; and engaging at least one shrouded end fitting with an end of the shrouded fluid-conducting apparatus.  
      In yet another form, the present invention provides a method for conducting fluid. Generally, the method comprises the steps of: shrouding at least one inner conduit, for example, by disposing the inner conduit within an outer conduit; allowing the inner conduit to transfer a load to an external component; placing the inner conduit in fluid communication with at least one other fluid-conducting apparatus; and delivering fluid to the inner conduit. To allow for coaxial fluid flow, the method may further comprise the step of delivering fluid to the outer conduit.  
      Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is a perspective view of a shrouded fluid-conducting apparatus constructed in accordance with the principles of the present invention;  
       FIG. 2  is a perspective view of the support member of the shrouded fluid-conducting apparatus shown in  FIG. 1 ;  
       FIG. 3  is a cross-sectional view of the shrouded fluid-conducting apparatus taken along the plane  3 - 3  in  FIG. 1 ;  
       FIG. 4  is a detailed cross-sectional view of portions of the support member and inner and outer conduits of the shrouded fluid-conducting apparatus shown in  FIG. 3 ;  
       FIG. 5  is a perspective view of a second embodiment of a shrouded fluid-conducting apparatus including a second embodiment of a support member constructed in accordance with the principles of the present invention;  
       FIG. 6  is another perspective view of the shrouded fluid-conducting apparatus shown in  FIG. 5  with its lower portion disposed in a second position;  
       FIG. 7  is yet another perspective view of the shrouded fluid-conducting apparatus shown in  FIG. 5  with its lower portion disposed in a third position;  
       FIG. 8  is a perspective view of the second embodiment of the support member shown in  FIGS. 5 through 7 ;  
       FIG. 9  is a cross-sectional view of the shrouded fluid-conducting apparatus taken along the plane  9 - 9  in  FIG. 5 ;  
       FIG. 10  is a detailed cross-sectional view of portions of the support member and inner and outer conduits of the shrouded fluid-conducting apparatus shown in  FIG. 9 ;  
       FIG. 11  is a perspective view of the shrouded end fitting shown in  FIG. 1 ;  
       FIG. 12  is a detailed cross-sectional view of portions of the shrouded end fitting and inner and outer conduits of the shrouded fluid-conducting apparatus shown in  FIG. 3 ;  
       FIG. 13  is a perspective view showing a first embodiment of a joint that may be used to engage a shrouded fluid-conducting apparatus with an additional shrouded fluid-conducting apparatus in accordance with the principles of the present invention;  
       FIG. 14  is a cutaway side view of the joint shown in  FIG. 13 ;  
       FIG. 15  is a detailed cutaway side view of a portion of the joint shown in  FIG. 14 ;  
       FIG. 16  is a perspective view of a third embodiment of the shrouded fluid-conducting apparatus constructed in accordance with the principles of the present invention;  
       FIG. 17  is a cross-sectional view of the shrouded fluid-conducting apparatus taken along the plane  17 - 17  in  FIG. 16 ;  
       FIG. 18  is a perspective of a second embodiment of a joint that may be used to engage a shrouded fluid-conducting apparatus with an additional shrouded fluid-conducting apparatus in accordance with the principles of the present invention;  
       FIG. 19  is a perspective view of the shrouded end fitting that is shown disposed at an end of the shrouded fluid-conducting apparatus in  FIG. 16 ;  
       FIG. 20  is a perspective view of the shrouded end fitting that is shown disposed at another end of the shrouded fluid-conducting apparatus in  FIG. 16  and that is engageable with the shrouded end fitting shown in  FIG. 19 ;  
       FIG. 21  is a cross-sectional side view illustrating the shrouded end fittings of  FIGS. 19 and 20  aligned for engagement;  
       FIG. 22  is a cutaway side view of the joint shown in  FIG. 18 ;  
       FIG. 23  is a perspective view of the support member shown in  FIG. 8  illustrating a fin that is configured for installation of a portion of a fluid control system constructed in accordance with the principles of the present invention;  
       FIG. 24  is a frontal view of the support member shown in  FIG. 23 ; and  
       FIG. 25  is a cross-sectional view of the support member taken along the plane  25 - 25  shown in  FIG. 24 .  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, it is anticipated that the invention will be applicable to any of a wide range of aircraft (e.g., but not limited to, fighter jets, commercial jets, private jets, propeller powered airplanes, among others) regardless of the manner in which the aircraft is piloted (e.g., directly, remotely, via automation, or in a combination thereof, among others). Indeed, the present invention need not even be limited to aircraft. Accordingly, the specific references to aircraft herein should not be construed as limiting the scope of the present invention. In addition, it is also anticipated that the invention will be applicable to any of a wide range of fluids, e.g., gases and liquids, regardless of whether the fluid is being used as a fuel. Accordingly, the specific references to fuel, gases, or liquids herein should not be construed as limiting the scope of the present invention.  
      In addition, certain terminology will also be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.  
       FIG. 1  is a perspective view of a shrouded fluid-conducting apparatus generally indicated by reference number  10 , according to one preferred embodiment of the present invention. Generally, the shrouded fluid-conducting apparatus  10  comprises at least one inner conduit  12  and at least one outer conduit  14  disposed around the inner conduit  12 . The outer conduit  14  includes a lumen that is sized to receive the inner conduit  12 . The inner conduit  12  includes a lumen that allows for a fluid (e.g., gases and liquids) flow through the inner conduit  12 . The outer conduit  14  shrouds the inner conduit  12  to contain any fluid leaking from the inner conduit  12  and thus prevent the leaking fluid from reaching the compartment in which the shrouded fluid-conducting apparatus  10  is being used. Accordingly, the inner and outer conduits  12  and  14  must both fail before a fluid being conducted through the inner conduit  12  can reach the compartment or space in which the shrouded fluid-conducted apparatus  10  is being used. The shrouded fluid-conducting apparatus  10  thus allows a fluid to be conducted through the inner conduit  12  under a double failure condition.  
      As further shown in  FIG. 1 , the shrouded fluid-conducting apparatus  10  may include at least one support member  20 . The various embodiments  20  and  120  of the support member are described in greater detail below. Briefly, however, the inner conduit  12  may be inclined to move or shift within the outer conduit  14  while a fluid is being conducted through the inner conduit  12 . The support member  20  prevents, or at least reduces, the movement of the inner conduit  12  within the outer conduit  14 . In other words, the support member  20  holds or keeps the inner conduit  12  substantially stationary with respect to the outer conduit  14 . Without the support member  20 , a sufficiently high pressure within the inner conduit  12  could cause the inner conduit  12  to strike or impact the outer conduit  14  with sufficient force to damage either or both of the conduits  12  and  14 . Accordingly, the support member  20  increases the stability and useful life of the shrouded fluid-conducting apparatus  10 . In addition, and as described in greater detail below, the support member  20  may also allow for the installation of at least a portion of a fluid control system, allow for curvature of the shrouded fluid-conducting apparatus  10 , and/or allow for loads to be transferred from the shrouded fluid-conducting apparatus  10  to an external component (e.g., ceiling joists, floor beams, and other load-bearing structures).  
      Still referring to  FIG. 1 , at least one shrouded end fitting  22  may be disposed at an end of the shrouded fluid-conducting apparatus  10 . Preferably, however, a shrouded end fitting  22  is disposed at each end of the shrouded fluid-conducting apparatus  10 . The various embodiments  22 ,  222 ,  223  of the shrouded end fittings are described in greater detail below. Briefly, however, the shrouded end fittings  22  may be used to connect the shrouded fluid-conducting apparatus  10  to an additional shrouded fluid-conducting apparatus  10 ′, as shown in  FIGS. 13 through 15 . Alternatively, the shrouded fluid-conducting apparatus  10  may be connected by way of the shrouded end fittings  22  to any one of a wide range of other fluid-conducting apparatus having end fittings mateable or engageable with the shrouded end fittings  22 , as would be obvious to one having ordinary skill in the art after having become familiar with the teaching of the present invention. The shrouded end fittings  22  may also be used to hold or keep the inner conduit  12  substantially stationary with respect to the outer conduit  14  and/or to transfer loads from the inner and outer conduits  12  and  14  to an external component (e.g., ceiling joists, floor beams, and other load-bearing structures).  
      It should be noted that although the Figures show a single support member  20 ,  120  disposed between two shrouded end fittings  22 ,  222 ,  223 , such need not be the case. For example, the shrouded fluid-conducting apparatus may comprise a plurality of (i.e., two or more) support members disposed between the two shrouded end fittings.  
       FIG. 2  is a perspective view of the support member  20 . As shown, the support member  20  preferably comprises concentric annular-shaped or ring-like members  24  and  26 . The inner and outer ring-like members  24  and  26  are separated by a spaced distance and accordingly define a leak detection passageway  45 , as shown in  FIG. 4 . The leak detection passageway  45  allows for a fluid flow between the inner and outer ring-like members  24  and  26 .  
      Referring back to  FIG. 2 , the support member  20  may further include a plurality of spokes, webs, or fins  38  that are disposed between the inner and outer ring-like members  24  and  26 . The inner ring-like member  24  includes a central opening  28  that is sized to receive the inner conduit  12 .  
      The outer ring-like member  26  is sized to be disposed around an end portion of the outer conduit  14 . Each end of the outer ring-like member  26  may be provided with a notch or weld socket  30  sized to allow the outer conduit portion  34  to be welded therein, as shown in  FIG. 4 .  
      When assembled, the support member  20  may have a two-fold purpose. First, the support member  20  may be used to hold the inner conduit  12  substantially stationary with respect to the outer conduit  14 . That is, the support member  20  may be used to compensate for or overcome the inclination of the inner conduit  12  to move or shift within the outer conduit  14  while the inner conduit  12  is conducting fluid. In addition, the support member  20  may also be used to allow for the transfer of loads from the inner and outer conduits  12  and  14  to an external component. Specifically, the inner conduit  12  may transfer loads arising from, for example, the weight of the inner conduit  12  and the weight of the fluid conducted thereby, to the support member  20 . The support member  20  may then transfer those loads to a component external to the shrouded fluid-conducting apparatus  10  to which the support member  20  may be engaged. Accordingly, the fins  38  of the support member  20  are preferably sized according to the loads that will be transferred thereto by the inner conduit  12 .  
      In addition, at least one fin  38  may be configured for allowing installation of at least a portion or a component of a fluid control system therein. For example, the fin  38  may be sufficiently thick to allow a passageway (e.g., threaded hole or bore) to be provided therethrough. If so, the shrouded fluid-conducting apparatus  10  may then be provided with a passageway that extends through each of the outer ring-like member  26 , the fin  38 , the inner ring-like member  24  and the inner conduit  12 . The passageway may then be used for installing a union or pipe coupling, a drain, a pressure regulator/monitor, among other components of a fluid control system in a manner similar to that shown in  FIGS. 23 through 25 , which illustrate the union  141  installed in the passageway  139  extending through the inner and outer ring-like members  124 ,  126  and the fin  138  of support member  120 .  
      Installation of a drain would allow for the removal of fluid from the inner conduit  12  thereby making the removal, repair, and/or replacement of the inner conduit  12  easier. Installation of a pressure regulator/monitor would allow for the pressure within the inner conduit  12  to be monitored and regulated. Depending on the pressure within the inner conduit  12 , the pressure regulator/monitor could send commands to a switch control for the pumps providing the fluid pressure to the inner conduit  12  to either increase, decrease, or maintain pressure. In either case, the passageway provided through the support member  20  and the inner conduit  12  might be capped with a heater coil and a plug (e.g., a threaded plug).  
       FIG. 3  is a cross-sectional view of the shrouded fluid-conducting apparatus  10  taken along the plane  3 - 3  shown in  FIG. 1 . Although the manner in which the support member  20  may be engaged with the inner and outer conduits  12  and  14  is shown  FIG. 3 , it is best shown in  FIG. 4 .  FIG. 4  is a detailed cross-sectional view of an upper portion (i.e., the portion disposed above the center line  40 ) of the support member  20  shown engaged with the inner and outer conduits  12  and  14 .  
      Referring to  FIGS. 3 and 4 , the support member  20  and the conduits  12  and  14  may be assembled in the following manner. First, the support member  20  is slidably positioned or disposed around the inner conduit  12 , which preferably comprises a single continuous member. As shown, the inner conduit  12  is positioned within the inner ring-like member  24  of support member  20 .  
      Next, the inner conduit  12  and inner ring-like member  24  are attached or secured to one another. For example, a compatible filler material may be used to weld (e.g., fillet weld, butt weld, etc.) the inner conduit  12  and inner ring-like member  24  to each other at any number of (i.e., one or more), but preferably at least two, locations thus creating weld joints  42 . Or for example, an adhesive may be used to secure the inner conduit  12  to the inner ring-like member  24 . Alternatively, other methods for attaching the inner conduit  12  to the inner ring-like member  24  are possible as would be obvious to one having ordinary skill in the art after having become familiar with the teachings of the invention.  
      After the inner conduit  12  has been attached to the inner ring-like member  24 , the outer conduit  14  is attached or secured to the outer ring-like member  26 . As shown, the outer conduit  14  comprises a first portion  34  and a second portion  44  between which is disposed the outer ring-like member  26 . The outer conduit portions  34  and  44  may be each welded (e.g., fillet weld, butt weld, etc.) to a corresponding weld socket  30  in the outer ring-like member  26  thus forming weld joints  36  between the support member  20  and the corresponding outer conduit portions  34  and  44 . Alternatively, other methods for attaching the outer conduit portions  34  and  44  to the outer ring-like member  26  may be possible as would be obvious to one having ordinary skill in the art after having become familiar with the teachings of the invention.  
      The inner and outer ring-like members  24  and  26  are preferably separated by a spaced distance and accordingly define the leak detection passageway  45 . The leak detection passageway  45  provides fluid communication between the outer conduit portions  34  and  44 . That is, the leak detection passageway  45  allows a fluid to flow from the outer conduit portion  34  or  44  into the other outer conduit portion  34  or  44 .  
      Preferably, a leak detection system is provided that is capable of detecting the presence of a leak in the inner conduit  12  and providing an appropriate warning thereof. For example, the leak detection system may detect the presence of a fluid within the outer conduit  14 . Or for example, the leak detection system may monitor the pressure within the outer conduit  14  and provide a warning if the pressure changes as a result of, for example, a fluid leaking into the outer conduit  14  from the inner conduit  12 . Because of the leak detection passageway  45 , a leak detection system is not necessarily needed for each of the outer conduit portions  34  and  44 . Instead, a single leak detection system provided along either conduit portion  34  or  44  may be used to detect fluid in either of the outer conduit portions  34  or  44 . In one embodiment, the leak detection system may comprise a weld boss that is welded to the outer conduit portion  34 , wherein pressure sensors or early detection lines are provided on the weld boss.  
      Any of a wide range of materials and manufacturing processes may be used to produce the support member  20 . The selection of material may depend at least in part on the materials comprising the inner and outer conduits  12  and  14  and the manner in which the inner and outer conduits  12  and  14  will be engaged with the support member  20 . The selection of manufacturing process may depend at least in part on the material that is selected for the support member  20 . Preferably, the support member material is preferably compatible with the conduit material(s), the method (e.g., welding) used to engage the support member  20  with the inner and outer conduits  12  and  14 , and the method used to make the support member  20 . By way of example only, the support member  20  may comprise aluminum (e.g., 6061-T4 aluminum) or stainless steel and be formed by a machining or milling process.  
       FIGS. 5, 6  and  7  are each perspective views of a second embodiment of a shrouded fluid-conducting apparatus  110  in which a portion  146  thereof that is disposed below the support member  120  is shown in respective first, second, and third positions  148 ,  150 ,  152 . The portion  164  of the shrouded fluid-conducting apparatus  110  disposed above the support member  120  is shown to be essentially in the same position in  FIGS. 5 through 7 .  
      The shrouded fluid-conducting apparatus  110  includes curved or bent inner and outer conduits  112  and  114 . To accommodate for the curvatures in the inner and outer conduits  112  and  114 , the second embodiment of the support member  120  is used. The support member  120  allows for curvature or flexure of the shrouded fluid-conducting apparatus  110  in the manner that is described in detail below. Accordingly, the shrouded fluid-conducting apparatus  110  may be used, for example, at corners or other locations where flexure or curvature is required.  
       FIG. 8  is a perspective view of the support member  120 . As before with the first embodiment  20 , the support member  120  may also comprise an inner ring-like member  124  and an outer ring-like member  126  that are separated by a spaced distance and accordingly define a leak detection passageway  145 , as shown in  FIG. 10 . The leak detection passageway  145  allows for a fluid flow between the inner and outer ring-like members  124  and  126 .  
      Referring back to  FIG. 8 , the support member  120  may also include a plurality of fins  138  that are disposed between the inner and outer ring-like members  124  and  126 . In addition, at least one fin  138  may be configured for allowing installation of at least a portion or a component of a fluid control system therein. For example, the fin  138  may be sufficiently thick to allow a passageway (e.g., threaded hole or bore) to be provided therethrough. As shown in  FIGS. 23 through 25 , the shrouded fluid-conducting apparatus  10  may then be provided with a passageway  139  that extends through each of the outer ring-like member  126 , the fin  138 , and the inner ring-like member  124 . The passageway  139  may then be used for installing the union or pipe coupling  141 , among other components of a fluid control system.  
       FIG. 9  is a cross-sectional view of the shrouded fluid-conducting apparatus  110  taken along the plane  9 - 9  in  FIG. 5 . Although shown in  FIG. 9 , the manner in which the support member  120  is engaged with the inner and outer conduits  112  and  114  is best shown in  FIG. 10 .  FIG. 10  is a detailed cross-sectional view of a portion (i.e., the portion disposed on a side of the center line  140 ) of the support member  120  shown engaged with the inner and outer conduits  112  and  114 .  
      As shown in  FIGS. 9 and 10 , the outer ring-like member  126  may be provided with notches or weld sockets  130  sized to allow the outer conduit portions  134  and  144  to be welded therein. Accordingly, a compatible filler material may be used to weld (e.g., fillet weld, butt weld, etc.) the outer conduit portions  134  and  144  to the weld sockets  130 , thus forming the weld joints  136 .  
      Unlike the first embodiment  20 , however, the inner ring-like member  124  of the support member  120  may also be provided with notches or weld sockets  154  sized to allow the inner conduit portions  158  and  162  to be welded therein. Accordingly, a compatible filler material may be used to weld (e.g., fillet weld, butt weld, etc.) the inner conduit portions  158  and  162  to the weld sockets  154 , thus forming the weld joints  160 . The weld sockets  154  provided in the inner ring-like member  124  may be essentially identical to the weld sockets  130  provided in the outer ring-like member  126 , although such need not be the case.  
      The support member  120  and the conduits  112  and  114  may be assembled in the following manner. The inner conduit portion  158  and outer conduit portion  134  may be rotated about the center line  140  to their proper positions. While the inner and outer conduit portions  158  and  134  are being rotated about the center line  140 , the end portions of the inner and outer conduit portions  158  and  134  may be kept square or flush with the support member  120 . After the proper positioning has been obtained, the inner conduit portion  158  may be welded to the weld socket  154 , and the outer conduit portion  134  may be welded to the weld socket  130 .  
      Next, the inner and outer conduit portions  162  and  144  may be twisted or rotated about the center line  140  to their proper positions. Once the proper positions have been obtained for the inner and outer conduit portions  162  and  144 , the inner and outer conduit portions  162  and  144  may then be welded to the respective weld sockets  154  and  130 .  
      It should be noted, however, that the inner and outer conduits  112  and  114  may be attached to the support member  120  in ways other than welding as would be obvious to one having ordinary skill in the art after having become familiar with the teachings of the invention. For example, an adhesive may be used to attach the inner and outer conduits  112  and  114  to the support member  120 .  
      To rotate the inner and outer conduits  112  and  114  with respect to the support member  120 , a vice may be used. The support member  120  may be held fast or stationary within the vice while the conduits  112  and  114  are being rotated. Alternatively, other methods may be used to rotate the conduits  112  and  114  with respect to the support member  120  as would be obvious to one having ordinary skill in the art after having become familiar with the teachings of the present invention.  
      As before with the first embodiment  20 , the support member  120  also preferably defines a leak detection passageway  145 . The leak detection passageway  145  provides fluid communication between the outer conduit portions  134  and  144 . That is, the leak detection passageway  145  allows a fluid to flow from the outer conduit portion  134  or  144  into the other outer conduit portion  134  or  144 . Accordingly, the leak detection passageway  145  provides advantages similar to that provided by the leak detection passageway  45  which were described previously.  
      Any of a wide range of materials and manufacturing processes may be used to produce the support member  120 . The selection of material may depend at least in part on the materials comprising the inner and outer conduits  112  and  114  and the manner in which the inner and outer conduits  112  and  114  will be engaged with the support member  120 . The selection of manufacturing process may depend at least in part on the material that is selected for the support member  120 . Preferably, the support member material is preferably compatible with the conduit material(s), the method used to engage the support member  120  with the inner and outer conduits  112  and  114 , and the method used to make the support member  120 . By way of example only, the support member  120  may comprise aluminum (e.g., 6061-T4 aluminum) or stainless steel and be formed by a machining or milling process.  
      As briefly described earlier and as shown in  FIGS. 1 and 3 , the shrouded fluid-conducting apparatus  10  has a shrouded end fitting  22  disposed at each of its opposed ends. The shrouded end fittings  22  are shown in detail in  FIGS. 11 through 15 .  
       FIG. 11  is a perspective view of the shrouded end fitting  22 . As shown, the shrouded end fitting  22  preferably comprises a ferrule-like shape. More specifically, the shrouded end fitting  22  comprises an inner portion  66  and an outer portion  68  that are separated by a spaced distance. The inner and outer portions  66  and  68  may be provided with notches or weld sockets  70  and  72 , respectively. As best shown in  FIG. 12 , the inner and outer conduits  12  and  14  may be welded (e.g., fillet weld, butt weld, etc.) into the weld sockets  70  and  72 , respectively.  
      Referring back to  FIG. 11 , the shrouded end fitting  22  may further include a plurality of spokes, webs, or fins  74  that are disposed between the inner and outer portions  66  and  68 . At least one of the fins  74  may be configured for allowing installation of at least a portion or component of a fluid control system therein. For example, the fin  74  may be sufficiently thick to allow a passageway (e.g., threaded hole) to be provided therethrough and into the inner conduit  12 . The passageway may then be used to install a union or pipe coupling, a drain, a pressure regulator/monitor, among other components of a fluid control system in a manner similar to that shown in  FIGS. 23 through 25 , which illustrate the union  141  installed in the passageway  139  (e.g., threaded hole or bore) extending through the inner and outer ring-like members  124 ,  126  and the fin  138  of support member  120 .  
      Any of a wide range of materials and manufacturing processes may be used to produce the shrouded end fitting  22 . The selection of material may depend at least in part on the materials comprising the inner and outer conduits  12  and  14  and the manner in which the inner and outer conduits  12  and  14  will be engaged with the shrouded end fitting  22 . The selection of manufacturing process may depend at least in part on the material that is selected for the shrouded end fitting  22 . Preferably, the material used for the shrouded end fitting  22  is compatible with the conduit material(s), the method used to engage the shrouded end fitting  22  with the inner and outer conduits  12  and  14 , and the method used to make the shrouded end fitting  22 . By way of example only, the shrouded end fitting  22  may comprise aluminum (e.g., 6061-T4 aluminum) or stainless steel and be formed by a machining or milling process.  
       FIG. 12  is detailed cross-sectional view showing portions of the inner and outer conduits  12  and  14  engaged with a portion of the shrouded end fitting  22  (i.e., the portion disposed above the center line  40  of the shrouded fluid-conducting apparatus  10 ). The inner and outer portions  66  and  68  of the shrouded end fittings  22  may each define a groove  76  and  78 , respectively, in which is disposed respective o-rings  80  and  82 . The o-rings  80  and  82  may assist with the fluidic sealing of the joint  84 .  
       FIG. 13  is a perspective view showing a first embodiment of the joint  84  that may be used to engage the shrouded fluid-conducting apparatus  10  with an additional shrouded fluid-conducting apparatus  10 ′. The joint  84  may be relatively flexible to allow for expansion and contraction of the joint  84  as the need arises. For example, the shrouded fluid-conducting apparatus  10  and  10 ′ may be disposed onboard a mobile platform (e.g., aircraft, train, bus, ship, etc.) wherein movement of the platform causes the need for at least some flexibility in the joint  84 .  
      By allowing the shrouded fluid-conducting apparatus  10  to be engaged with additional shrouded fluid-conducting apparatus  10 ′, greater flexibility is provided to the installer of the overall fluid-conducting system. During the installation process of a fluid-conducting system, tight places and corners are often encountered that require the installer to use shorter components. At such locations, the installer may use one or more shorter length shrouded fluid-conducting apparatus  10  and  10 ′. The present invention thus allows for the use of shorter shrouded fluid-conducting apparatus  10  in places where shorter conduit lengths are required but still allows for longer shrouded fluid-conducting apparatus  10  to be used in other places.  
      To allow for electrical grounding across the joint  84 , a bonding jumper  86  (e.g., electrically conductive wire or strap, etc.) may be used in conjunction with loop-type bonding clamps  88  and  88 ′ disposed circumferentially around the outer conduits  14  and  14 ′, respectively. By providing the bonding jumper  86  and clamps  88 ,  88 ′ across each joint (e.g.,  84 ) in the fluid system, the entirety of the fluid-conducting system may be grounded when a single component of the fluid-conducting system is grounded.  
       FIG. 14  is a cutaway side view of the joint  84 . Although shown in  FIG. 14 , the manner in which the shrouded fluid-conducting apparatus  10  and  10 ′ are engaged with each other is best shown in  FIG. 15 .  FIG. 15  is a detailed cutaway side view of a portion (i.e., the portion disposed below the center line  40 ) of the joint  84 .  
      Referring to  FIGS. 14 and 15 , the joint  84  may be used to engage the shrouded fluid-conducting apparatus  10  and  10 ′ with each other. As shown, the joint  84  comprises the shrouded end fittings  22  and  22 ′. The joint  84  further includes an inner and outer coupling assembly  90  and  92  and an inner and outer seal sleeve  94  and  96 .  
      To assemble the joint  84 , the shrouded end fittings  22  and  22 ′ are first positioned adjacent one another. Next, the inner seal sleeve  94  is disposed around the o-rings  80  and  80 ′ and portions  66  and  66 ′ of the shrouded end fittings  22  and  22 ′. The inner coupling assembly  90  is then disposed or clamped around the inner seal sleeve  94 , the shrouded end fitting portions  66  and  66 ′ and the o-rings  80  and  80 ′. Accordingly, the inner coupling assembly  90  and inner seal sleeve  94  fluidically seal the junction between the inner conduits  12  and  12 ′.  
      Continuing with the joint  84  assembly process, the outer seal sleeve  96  is then disposed around the o-rings  82  and  82 ′ and portions  68  and  68 ′ of the shrouded end fittings  22  and  22 ′. Next, the outer coupling assembly  92  is disposed or clamped around the outer seal sleeve  96 , the shrouded end fitting inner portions  68  and  68 ′ and the o-rings  82  and  82 ′. Accordingly, the outer coupling assembly  92  and outer seal sleeve  96  fluidically seal the junction between the outer conduits  14  and  14 ′.  
      In addition, the inner and outer coupling assemblies  90  and  92  and the inner and outer seal sleeves  94  and  96  prevent, or at least hinder, axial movement of the shrouded fluid-conducting apparatus  10  and  10 ′ away from each other.  
      The joint  84  also allows for fluid to be conducted from one inner conduit  12  or  12 ′ to the other inner conduit  12  or  12 ′ under a double failure condition in that two failures must occur before that fluid can reach the compartment (e.g., an aircraft “ignition zone”) in which the shrouded fluid-conducted apparatus  10  or  10 ′ are disposed. For example, if a failure allows the fluid within the inner conduit  12  or  12 ′ to reach the outer conduit  14  or  14 ′, the outer coupling assembly  92  and outer seal sleeve  96  do not allow the fluid within the outer conduit  14  or  14 ′ to enter the compartment.  
      Preferably, the joint  84  allows the inner conduits  12  and  12 ′ to be fluid communication with each other and also defines a leak detection passageway  98  that allows the outer conduits  14  and  14 ′ to be in fluid communication with each other. The leak detection passageway  98  is preferably defined at least partially between the inner coupling assembly  90  and the outer seal sleeve  96 . The leak detection passageway  98  allows a fluid to flow from the outer conduit  14  or  14 ′ into the other outer conduit  14  or  14 ′. With the leak detection passageway  98 , a leak detection system is not necessarily needed for each of the shrouded fluid-conducting apparatus  10  and  10 ′. Instead, a single leak detection system may be used to detect fluid in either of the outer conduits  14  or  14 ′.  
       FIG. 16  is a perspective view of a third embodiment of a shrouded fluid-conducting apparatus  210 . As shown, the shrouded fluid-conducting apparatus  210  comprises a support member  20  and is substantially straight, as was the first embodiment 10. However, the shrouded fluid-conducting apparatus  210  includes shrouded end fittings  222  and  223  disposed at its ends.  
       FIG. 17  is a cross-sectional view of the shrouded fluid-conducting apparatus  210  taken along the plane  17 - 17  in  FIG. 16 . As before with the first embodiment 10 shown in  FIG. 3 , the shrouded fluid-conducting apparatus  210  comprises an inner conduit  12  and an outer conduit  14 , wherein the outer conduit  14  includes first and second portions  34  and  44  disposed between the support member  20 .  
       FIG. 18  is a perspective view showing a joint  284  that may be used to engage the shrouded fluid-conducting apparatus  210  with an additional shrouded fluid-conducting apparatus  210 ′. As shown, the joint  284  may comprise the shrouded end fittings  222  and  223 ′ disposed at the respective ends of the shrouded fluid-conducting apparatus  210  and  210 ′. The shrouded end fittings  222  and  223 ′ may be engaged with each other by way of mechanical fasteners  285  (e.g., lugs, device pins, single pin joints, screws, rivets, among others).  
      The joint  284  is preferably a relatively fixed joint that allows for the transfer of loads from one shrouded fluid-conducting apparatus  210  or  210 ′ to the other and/or from the shrouded fluid-conducting apparatus  210  and  210 ′ to an external component (e.g., ceiling joist, floor beam, other load-bearing structures, etc.). For example, it may be necessary for the fluid-conducting system to span across a large area such that either or both of the shrouded fluid conducting apparatus  210  or  210 ′ may need to have considerable length. Or for example, the shrouded fluid-conducting apparatus  210  and  210 ′ may be required to conduct a fluid at a relatively high pressure, thus requiring the inner conduits  12  and  12 ′ to be fabricated from a relatively heavy material having sufficient strength to withstand the fluid pressures. In either case, the weight of the shrouded fluid-conducting apparatus  210  and  210 ′ may be considerable, and the joint  284  may allow for the weight to be transferred or supported by an external component.  
       FIG. 19  is a perspective view of the shrouded end fitting  222 . As shown, the shrouded end fitting  222  comprises an inner portion  266  and an outer portion  268  that are separated by a spaced distance. The outer portion  268  preferably comprises a flange  267  that defines a plurality of holes  269  sized to receive the mechanical fasteners  285  therethrough. The shrouded end fitting  222  may further include a plurality of spokes, webs, or fins  274  that are disposed between the inner and outer portions  266  and  268 .  
       FIG. 20  is a perspective view of the shrouded end fitting  223 . As shown, the shrouded end fitting  223  comprises an inner portion  271  and an outer portion  273  that are separated by a spaced distance. The outer portion  273  preferably comprises a flange  283  that defines a plurality of holes  275  that are sized to receive the mechanical fasteners  285  therethrough. The shrouded end fitting  223  may further include a plurality of spokes, webs, or fins  277  that are disposed between the inner and outer portions  271  and  273 .  
      One or more of the fins  274  and  277  of the shrouded end fittings  222  and  223 , respectively, may be configured for allowing installation of at least a portion or a component of a fluid control system therein. That is, one or more of the fins  274  and  277  may be sufficiently thick to allow a passageway to be provided therethrough, which may then be used for installation of a union or pipe coupling, a drain, a pressure regulator, and/or other components of a fluid control system in a manner similar to that shown in  FIGS. 23 through 25 , which illustrate the union  141  installed in the passageway  139  extending through the inner and outer ring-like members  124 ,  126  and the fin  138  of support member  120 .  
      Any of a wide range of materials and manufacturing processes may be used to produce the shrouded end fittings  222 ,  223 . The selection of material may depend at least in part on the materials comprising the inner and outer conduits  12  and  14  and the manner in which the inner and outer conduits  12  and  14  will be engaged with the shrouded end fittings  222 ,  223 . The selection of manufacturing process may depend at least in part on the material that is selected for the shrouded end fittings  222 ,  223 . Preferably, the material used for the shrouded end fittings  222 ,  223  is compatible with the conduit material(s), the method used to engage the shrouded end fittings  222 ,  223  with the inner and outer conduits  12  and  14 , and the method used to make the shrouded end fittings  222 ,  223 . By way of example only, the shrouded end fittings  222 ,  223  may comprise aluminum (e.g., 6061-T4 aluminum) or stainless steel and be formed by a machining or milling process.  
       FIG. 21  is a cross-sectional side view illustrating a portion (i.e., the portion disposed above the center line  240 ) of the shrouded end fitting  222  of  FIG. 19  aligned for engagement with a corresponding portion of a shrouded end fitting  223 ′ disposed at an end of the shrouded fluid-conducting apparatus  210 ′. As shown, the inner and outer portions  266  and  268  of the shrouded end fitting  222  may be provided with notches or weld sockets  270  and  272  into which may be welded (e.g., fillet weld, butt weld, etc.) the inner and outer conduits  12  and  14 , respectively. The inner and outer portions  273 ′ and  275 ′ of the shrouded end fitting  223 ′ may also be provided with notches or weld sockets  279 ′ and  281 ′ into which may be welded (e.g., fillet weld, butt weld, etc.) the inner and outer conduits  12 ′ and  14 ′, respectively. Additionally, the inner and outer portions  273 ′ and  275 ′ of the shrouded end fittings  223 ′ may each define a groove  276 ′ and  278 ′, respectively, in which is disposed respective o-rings  280 ′ and  282 ′. The o-rings  280 ′ and  282 ′ may assist with the fluidic sealing of the joint  284 .  
      To ensure proper alignment of the shrouded end fittings  222  and  223 ′, the shrouded end fittings  222  and  223 ′ may be shaped to interfit with one another in a keyed arrangement or one relation alignment. For example, the shrouded end fitting  222  may comprise an alignment tab or key  287  that is sized to fit within a notch or keyway  289 ′ defined by the shrouded end fitting  223 ′. Or for example, the shrouded end fitting  222  may, additionally or alternatively, include a radial protrusion  291  that is disposed to engage a chamfered or beveled surface  293 ′ defined by the shrouded end fitting  223 ′. In other embodiments, the shrouded end fitting  223 ′ may be provided with the alignment tab and/or the radial protrusion, and the shrouded end fitting  222  may be provided with the notch and/or the chamfered surface.  
       FIG. 22  is a cutaway side view of the joint  284 . As shown, a bonding jumper  286  (e.g., wire, strap, etc.) may be used in conjunction with loop-type bonding clamps  288  and  288 ′ disposed circumferentially around the outer conduits  14  and  14 ′, respectively, to allow for electrical grounding across the joint  284 . By providing the jumper wire  286  and clamps  288  and  288 ′ across each joint (e.g.,  284 ) in the fluid-conducting system, the entirety of the fluid system may be grounded when a single component of the fluid-conducting system is grounded.  
      Preferably, the joint  284  allows for fluid communication between the inner conduits  12  and  12 ′ and also defines a leak detection passageway  298  that allows for fluid communication between the outer conduits  14  an  14 ′. With the leak detection passageway  298 , a leak detection system is not necessarily needed for each of the shrouded fluid-conducting apparatus  210  and  210 ′. Instead, a single leak detection system may be used to detect fluid in either of the outer conduits  14  or  14 ′.  
      In a fourth embodiment of the shrouded fluid-conducted apparatus that is not shown, the shrouded fluid-conducting apparatus may include the support member  120  and the shrouded end fittings  222  and  223 .  
      It should be noted that any of the aforementioned embodiments of the shrouded fluid-conducting apparatus  10 ,  110 ,  210  may be used to provide a coaxial fluid flow. That is, the inner and outer conduits  12 ,  112  and  14 ,  114  of the shrouded fluid-conducting apparatus  10 ,  110 ,  210  may both be used to transport fluids at the same time. Moreover, the fluids being conducted by the inner conduit  12 ,  112  and the outer conduit  14 ,  114  may be either the same fluid or different fluids. In addition, the fluids may be conducted in either the same or different directions. For example, the inner conduit  12  of the shrouded fluid-conducting apparatus  10  may be used as fluid supply conduit, while the outer conduit  14  is used as a fluid return conduit.  
      Dimensionally, in one preferred embodiment, the inner conduit  12  is sized such that its inner diameter is about 4.87 inches (12.37 cm), its outer diameter is about 5.0 inches (12.7 cm), and its wall thickness is about 0.065 inches (0.165 cm). The outer conduit  14  is sized such its inner diameter is about 5.87 inches (14.91 cm), its outer diameter is about 6.0 inches (15.24 cm), and its wall thickness is about 0.065 inches (0.165 cm). The support member  20 ,  120  is sized such that its inner diameter is about 4.87 inches (12.37 cm) and its minimum outer diameter is about 6.14 inches (15.6 cm), which may be increased to accommodate for support features such as lugs, device pins, etc. The shrouded end fitting  22 ,  222 ,  223  is sized such that its inner diameter is about 4.87 inches (12.37 cm) and its outer diameter is about 6.51 inches (16.54 cm). Accordingly, the shrouded fluid-conducting apparatus  10  is compatible with the standard-sized aerial refueling manifolds currently being used.  
      In another preferred embodiment, the inner conduit  12  is sized such that its inner diameter is about 3.92 inches (9.96 cm), its outer diameter is about 4.0 inches (10.16 cm), and its wall thickness is about 0.042 inches (0.107 cm). The outer conduit  14  is sized such that its inner diameter is about 4.87 inches (12.37 cm), its outer diameter is about 5.0 inches (12.7 cm), and its wall thickness is about 0.042 inches (0.107 cm). The support member  20 ,  120  is sized such that its inner diameter is about 3.87 inches (9.83 cm) and its minimum outer diameter is about 5.14 inches (13.06 cm), which may be increased to accommodate for support features such as lugs, device pins, etc. The shrouded end fitting  22 ,  222 ,  223  is sized such that its inner diameter is about 3.87 inches (9.83 cm) and its outer diameter is about 5.51 inches (14 cm).  
      It should be noted, however, that the present invention is not limited to any particularly sized inner and/or outer conduit. That is, other conduit sizes may be employed without departing from the spirit and scope of the present invention.  
      In another form, the present invention provides a method of manufacturing or making a shrouded fluid-conducting apparatus. Generally, the method comprises the steps of: disposing an inner conduit within an outer conduit; engaging a support member with the inner and outer conduits; and engaging at least one shrouded end fitting with an end of the shrouded fluid-conducting apparatus.  
      According to one preferred embodiment, the method of making the shrouded fluid-conducting apparatus  10 ,  210  preferably comprises the following steps. The support member  20  and the shrouded end fittings  22 ,  222 ,  223  are made (e.g., machined, milled, among other manufacturing processes) from an appropriate material (e.g., aluminum, stainless steel, composites, among other materials). The support member  20  is slidably positioned around a portion of the inner conduit  12 . A compatible filler material is used to weld the support member  20  to the inner conduit  12 . The outer conduit portions  34 ,  44  are slidably positioned over the respective portions of the inner conduit  12  that extend outwardly from each side of the support member  20 . A compatible filler material is used to weld the outer conduit portions  34 ,  44  to the weld sockets  30  defined by the outer ring-like member  26  of the support member  20 . The appropriate shrouded end fitting  22 ,  222 ,  223  is then welded to each end of the shrouded fluid-conducting apparatus  10 ,  210 . Finally, the shrouded fluid-conducting apparatus  10 ,  210  is proof pressure tested.  
      In another preferred embodiment, the method of making the shrouded fluid-conducting apparatus  110  preferably comprises the following steps. The support member  120  and the shrouded end fittings  22 ,  222 ,  223  are made from an appropriate material (e.g., aluminum, stainless steel, among others). The inner and outer conduit portions  158 ,  162 ,  134 ,  144  are assembled to the support member  120  in the manner previously described. The appropriate shrouded end fitting  22 ,  222 ,  223  are then welded to each end of the shrouded fluid-conducting apparatus  110 . Finally, the shrouded fluid-conducting apparatus  110  is proof pressure tested.  
      In yet another form, the present invention provides a method for conducting fluid. Generally, the method comprises the steps of: shrouding an inner conduit  12 ,  112 , for example, by disposing the inner conduit  12 , 112 , within an outer conduit  14 ,  114 ; allowing the inner conduit  12 ,  112 , to transfer a load to an external component; placing the inner conduit  12 ,  114  in fluid communication with at least one other fluid-conducting apparatus (e.g., the inner conduit  12 ′,  112 ′ of the shrouded fluid-conducting apparatus  10 ′,  110 ′,  210 ′); and delivering fluid to the inner conduit  12 ,  112 . To allow for coaxial fluid flow, the method may further comprise the step of delivering fluid to the outer conduit  14 ,  114 .  
      Accordingly, the present invention provides a shrouded fluid-conducting apparatus that may be used to conduct fuel through an FAA classified “ignition zone” of an aircraft in an FAA-compliant manner. By using the shrouded fluid-conducting apparatus of the present invention, fuel may be transported through an aircraft “ignition zone” or through other places under a double failure condition.  
      Previously, the FAA regulations allowed fuel to be conducted through single-wall conduits. However, the FAA regulations now require that fuel being transported through aircraft “ignition zones” must be contained within a shrouded conduit so that no single failure (e.g., leak or rupture of a conduit) will jeopardize the safe operation of an aircraft. By installing or retrofitting aircraft with the shrouded fluid-conducting apparatus of the present invention, the aircraft will satisfy the FAA regulations pertaining to the use of shrouded fuel lines. For example, the shrouded fluid-conducting apparatus may be installed or retrofitted onto existing aircraft such as the B-747® family of aircraft (e.g., E-4B, 747-200B, among others), the B-767® family of aircraft (e.g., Global Tanker Transport Aircraft (GTTA), AWACS Airborne Warning and Control System, among others), and/or the B-737® family of aircraft (e.g., Wedge tail, among others) from The Boeing Company. By retrofitting any of these existing aircraft with the shrouded fluid-conducting apparatus, the aircraft will be capable of being FAA certified by means of a Supplemental Type Certificate (STC). The shrouded fluid-conducting apparatus is also qualified for military applications under existing military standards.  
      In addition, the support members and joints each define leak detection passages used in conjunction with the shrouded fluid-conducting apparatus each define leak detection passageways. These leak detection passageways allow a single leak detection system to detect leaks across a plurality of shrouded fluid-conducting apparatus.  
      The joints also have advantages associated with them. For example, the joint  84  provides a relatively flexible connection that is able to expand and contract as the need arises. Or for example, the joint  284  provides a relatively fixed connection that allows for the transfer of loads across the joint  284  from one shrouded fluid-conducting apparatus to another and/or from one shrouded fluid-conducting apparatus to an external component.  
      The present invention also allows the shrouded fluid-conducting apparatus to be removed and/or replaced as a single unit. Accordingly, the shrouded fluid-conducting apparatus may be conveniently removed and/or replaced without having to remove surrounding support structure or other components of the overall fluid-conducting system of which the shrouded fluid-conducting apparatus is a part.  
      Moreover, the present invention also allows for various lengths, sizes (e.g., inner and outer diameters), and shapes (e.g., straight, curved) to be used for the shrouded fluid-conducting apparatus. For example, an installer may select a shrouded fluid-conducting apparatus having an appropriate length, curvature or flexure to accommodate for tight places, corners, and/or immovable objects around which the shrouded fluid-conducting apparatus must be positioned. Accordingly, the present invention provides great flexibility to the installer of the shrouded fluid-conducting apparatus. Indeed, the shrouded fluid-conducting apparatus can be tailored to any of a wide range of fluid-conducting systems.  
      The shrouded fluid-conducting apparatus is also more economical to manufacture than the shrouded conduits presently recognized in the art. Moreover, the present invention also allows for the use of standard bend radii with the shrouded fluid-conducting apparatus and for the use of currently existing tube clamps (e.g., bonding clamps  88 ,  288 ), tube supports, and tube mounting means. Accordingly, the shrouded fluid-conducting apparatus can be easily retrofit to other fluid-conducting systems in aircraft, among other locations.  
      The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the substance of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.