Abstract:
Insulated piping and methods of making and using insulated piping are disclosed herein. An insulated pipe according to one embodiment includes a plurality of elongate pipe sections. Each pipe section includes first and second ends, an inner pipe for transporting temperature sensitive fluids, an intermediate pipe extending around the inner pipe, and an outer pipe extending around the inner pipe and the intermediate pipe. The inner pipe is operatively coupled to the outer pipe to form an airtight insulation space between the inner and outer pipes, and the intermediate pipe segregates the airtight insulation space into a plurality of independent insulation spaces between the inner and outer pipes. At least one independent insulation space is radially inward of another independent insulation space.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority to U.S. Provisional Patent Application Ser. Nos. 60/913,727, filed Apr. 24, 2007, and 60/939,070, filed May 20, 2007. Each of these applications is incorporated by reference herein. 
     
    
     FIELD OF INVENTION 
       [0002]    The present disclosure relates generally to insulated piping and, more particularly, to prefabricated multi-chamber vacuum insulated pipe sections and methods for connecting them, for example to provide freeze-free water pipes. 
       BACKGROUND 
       [0003]    Insulated pipes are used in a wide variety of industrial applications to prevent thermal leakage. For example, thermally insulated piping is used to transport cryogenic liquids. There are three types of commonly used insulated piping: foam insulated copper pipe, dynamic vacuum insulated pipe and static vacuum insulated pipe. 
         [0004]    Foam insulated copper pipe is one type of prefabricated pipe with sections constructed of copper surrounded by foam insulation. While foam insulated copper pipe is cost efficient, it may not perform well under extreme conditions. The foam insulation is surrounded and protected by a plastic casing; however over time the insulation tends to absorb water from the atmosphere. As the insulation absorbs water it becomes less efficient and new insulation is required. Sections of foam insulated copper pipe are typically joined by brazing or butt-welding and foam insulation is fitted around the joint. 
         [0005]    Dynamic vacuum insulated pipe requires a vacuum system that is continuously running. While this pipe is more efficient than foam insulated pipe, there is an added cost of frequent pump maintenance and electrical power to run the pump(s). Additionally, if a vacuum pump fails then a whole pipe section may lose its vacuum, and hence its insulating properties becoming extremely inefficient. 
         [0006]    Static vacuum insulated pipe is prefabricated and the vacuum is achieved and permanently sealed. One advantage of static insulated pipe is the equipment used to create the vacuum in the factory may be of better quality than equipment deployed in the field for use in a dynamic vacuum pipe. Static vacuum insulated pipe may however be susceptible to puncture; a punctured pipe may lose its vacuum and insulating properties and become extremely inefficient. Thermal loss may also occur at the joints because it is prefabricated and the joints may not be vacuum insulated. 
       SUMMARY 
       [0007]    A vacuum insulated pipe according to one embodiment includes a plurality of pipe sections and at least one insulated pipe connector, and the plurality of insulated pipe sections are connected together by the one or more insulated pipe connectors. Each insulated pipe section has an outer pipe and an inner pipe generally concentric to the outer pipe for transporting temperature sensitive fluids. The outer and inner pipes form a first evacuated insulation space. A first end plate is included for sealing a first end of the first evacuated insulation space, and a second end plate is included for sealing a second end of the first evacuated insulation space. Each insulated pipe connector has an outer pipe and an inner pipe generally concentric to the connector outer pipe. The outer and inner connector pipes form a second evacuated insulation space. A first end plate is included for sealing a first end of the second evacuated insulation space, and a second end plate is included for sealing a second end of the second evacuated insulation space. 
         [0008]    A vacuum insulated pipe section according to one embodiment includes an inner pipe for transporting temperature sensitive fluids and an outer pipe extending around the inner pipe. An evacuated insulation space is between the outer and inner pipes. A first end plate seals at least a portion of a first end of the insulation space, and a second end plate seals at least a portion of a second end of the insulation space. The outer pipe extends beyond the inner pipe in a first direction, and female threads are formed inside the outer pipe beyond the first end plate. The inner pipe extends beyond the outer pipe in a second direction, and male threads are formed outside the inner pipe beyond the outer pipe for coupling to female threads of another vacuum insulated pipe section. 
         [0009]    An insulated pipe according to one embodiment includes a plurality of elongate pipe sections. Each pipe section includes first and second ends, an inner pipe for transporting temperature sensitive fluids, an intermediate pipe extending around the inner pipe, and an outer pipe extending around the inner pipe and the intermediate pipe. The inner pipe is operatively coupled to the outer pipe to form an airtight insulation space between the inner and outer pipes, and the intermediate pipe segregates the airtight insulation space into a plurality of independent insulation spaces between the inner and outer pipes. At least one independent insulation space is radially inward of another independent insulation space. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0010]      FIG. 1A  shows an exploded view of a prefabricated insulated pipe section. 
           [0011]      FIG. 1B  shows a top perspective view of a pipe section. 
           [0012]      FIG. 2A  shows an exploded view of a pipe joint. 
           [0013]      FIG. 2B  shows a top perspective view of pipe joint. 
           [0014]      FIG. 3  shows an example a pipe system using pipe joints. 
           [0015]      FIG. 4A  shows cross-section of a pipe section. 
           [0016]      FIG. 4B  shows a perspective view of a punctured pipe section. 
           [0017]      FIG. 5  shows a cross-section of a multi-chamber joint  20 . 
           [0018]      FIG. 6A  and  FIG. 6B  show pipe sections with male and female threaded inter-connecting ends. 
           [0019]      FIG. 7  shows an example of a threaded multi-chamber pipe system. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    A multi-chamber vacuum pipe system is described hereinbelow to provide a cost effective puncture-resistant insulated pipe and joint that may be produced and utilized in prefabricated sections. Other advantages will become more apparent in the following detailed description of the inventions. 
         [0021]      FIG. 1A  shows an exploded view of a prefabricated insulated pipe section  10  with an inner pipe  30  for transporting temperature sensitive liquids and a concentric outer pipe  70 , positioned such that an annular insulation space  35  is formed therebetween. Annular insulation space  35  is sealed by pipe end plates  14   a  and  14   b  at either end of pipes  30  and  70 . The annular insulation space may be further dived into two pipe chambers  35   a  and  35   b  by chamber walls  38   a  and  38   b , as shown. Outer pipe  70  may be made with thicker material than inner pipe  30  to increase puncture resistance of insulated pipe section  10 . Pipe section  10  has a length L 1 , which may, for example, be between 0.1 m and 10 m, depending upon application. In one embodiment, insulated pipe section  10  is fabricated of hardened plastic; however in other embodiments insulate pipe section  10  may be constructed of ferrous or non-ferrous metal or of a metal plastic hybrid. Insulated pipe section  10  may, for example, be used to transport temperature sensitive liquids within inner pipe  30 . 
         [0022]    In one exemplary method of construction, outer pipe  70 , inner pipe  30  and chamber walls  38   a ,  38   b  are formed by extrusion or any other appropriate method. Annular insulation space  35  is, for example, sealed at one end by pipe end plate  14   a , air is removed therefrom, and pipe end plate  14   b  is then attached to seal insulation space  35  and maintain the vacuum therein. Vacuum sealing may occur within a vacuum chamber. Alternately, or additionally, after fitting of pipe end plates  14   a ,  14   b  to outer pipe  70 , inner pipe  30  and chamber walls  38 , one or more small hole  39  in pipe end plate  14   a  may be used to permit air to be withdrawn from insulation space  35 ; hole(s)  39  may then be sealed to maintain the vacuum within insulation space  35 . The vacuum within insulation space  35  may be created by other means known in the art without departing from the scope hereof. 
         [0023]      FIG. 1B  shows a top perspective view of pipe section  10 , in accord with one embodiment. 
         [0024]      FIG. 2A  shows an exploded view of one exemplary embodiment of an insulated pipe joint  20 . Pipe joint  20  has an inner pipe  26  and an outer pipe  28  positioned such that an annular insulation space  25  is formed therebetween. Insulation space  25  is sealed by joint end plates  24   a  and  24   b . Pipe joint  20  has a length L 3 , which may, for example, be between 0.1 m and 0.25 m, depending upon application. Inner pipe  26  has an internal diameter D 5  so that pipe section  10  can slide into either side of joint  20  (i.e., through joint end plates  24   a  and  24   b ). Though not shown, insulation space  25  may be divided into multiple chambers by chamber walls. 
         [0025]    In one exemplary method of construction, outer pipe  28  and inner pipe  26  are formed by extrusion or any other appropriate method. Insulation space  25  is, for example, sealed at one end by joint end plate  24   a , air is removed therefrom, and joint end plate  24   b  is then attached to seal insulation space  25  and maintain the vacuum therein. Vacuum sealing may occur within a vacuum chamber. Alternately, or additionally, after fitting of joint end plates  24   a ,  24   b  to outer pipe  28  and inner pipe  26 , one or more small hole  29  in joint end plate  24   a  may be used to permit air to be withdrawn from insulation space  25 ; hole(s)  29  may then be sealed to maintain the vacuum within insulation space  25 . The vacuum within insulation space  25  may be created by other means known in the art without departing from the scope hereof. 
         [0026]      FIG. 2B  shows a perspective view of pipe joint  20  of  FIG. 2A  once assembled. Pipe joint  20  may also include a pipe stop  22 , as shown in  FIG. 2B , that prevents pipe section  10  from passing more than halfway through pipe joint  20  during insertion. Pipe section  10  and pipe joint  20  may be attached using pipe adhesive or other methods known in the art; the method employed may be selected to prevent thermal leakage. Pipe stop  22  may protrude at least partially along the circumference of inner pipe  26  in the center of pipe joint  20 . In other embodiments, pipe stop  22  may be formed as a gradual reduction in the diameter of inner pipe  26  towards the center of inner pipe  26 . 
         [0027]      FIG. 3  shows one exemplary pipe system  100  with two pipe sections  10  (labeled  10 ( 1 ) and  10 ( 2 ), respectively) and a pipe joint  20 . Although shown with two pipe sections  10  and one pipe joint  20 , pipe system  100  may contain additional pipe sections  10  and joints  20  to form a longer insulated section of pipe. It should be appreciated that one or more pipe section  10  and/or pipe joint  20  may be nonlinear (e.g., curved, angled, etc.) and that the resultant pipe system may therefore be nonlinear. 
         [0028]      FIG. 4A  shows a cross-section through one exemplary embodiment of a pipe section  210 . Pipe section  210  may, for example, represent pipe section  10  ( FIG. 1A ). Pipe section  210  is, for example, formed with an outer pipe  270  and four concentric inner pipes  260 ,  250 ,  240 , and  230  to form insulating spaces  275 ,  265 ,  255 , and  245 . Pipes  230 ,  240 ,  250 ,  260 , and  270  are generally concentric and are shown with diameters D 1 , D 2 , D 3 , D 4 , and D 5 , respectively. Insulating spaces  275 ,  265 ,  255 , and  245  may be divided into sub-spaces by chamber walls  278 ,  268 ,  258 , and  248 , respectively. 
         [0029]    Outer pipe  270  may, for example, be made of thicker material than inner pipes  260 ,  250 ,  240 , and  230  and walls  278 ,  268 ,  258 , and  248  to increase puncture resistance of pipe section  210 . Though not specifically shown, an additional outer casing may be formed around pipe section  210  in increase durability of pipe section  210 . Some embodiments may include variation in thickness of inner pipes  260 ,  250 ,  240 , and  230  and/or walls  278 ,  268 ,  258 , and  248  without departing from the scope hereof. 
         [0030]    Pipe section  210  may include pipe end plates (not shown) that seal insulating spaces  275 ,  265 ,  255  and  245 ; these end plates may, for example, be similar to end plates  14   a ,  14   b  of  FIG. 1A . Air may be evacuated from insulating spaces  275 ,  265 ,  255  and  245  to improve insulation of fluids transported within inner pipe  230 . Each sub-space of insulating spaces  275 ,  265 ,  255  and  245  (e.g., sub-spaces  275   a ,  275   b ,  275   c , etc.) may be sealed to prevent fluid flow between sub-spaces. The number of insulating spaces and sub-spaces may vary without departing from the scope hereof. In some embodiments, insulating spaces  275 ,  265 ,  255  and  245  have equal vacuum. In other embodiments, vacuum within insulating spaces  275 ,  265 ,  255  and  245  varies; for example, vacuum may increase towards the center of pipe section  210 . 
         [0031]    Pipe section  210  may be rated based upon its insulation properties and the material from which it is constructed. For example, pipe section  210  may be used to transport water through a mountainous environment prone to temperatures 20 degrees Celsius (C) below the freezing point of water and therefore requires that pipe section  210  be rated for −20° C. In another example, pipe section  210  may transport water through an environment that has lesser extremes and therefore need only be rated for −10° C. To achieve lower temperature ratings (e.g., −20° C.), pipe section  210  may have more internal pipes (e.g., internal pipes  230 ,  240 ,  250  and  260 ) and additional sub-spaces within each insulating space (e.g., sub-spaces  275   a ,  275   b , and  275   c  within insulating space  275 ). Vacuum properties of pipe section  210  (e.g., gas pressure between the exterior pipe  270  and the inner pipe  230 ) may also be altered to achieve different temperature ratings. 
         [0032]    In some embodiments, pipes  230 ,  240 ,  250 ,  260 , and  270  and chamber walls  278 ,  268 ,  258 , and  248  are formed from plastic using extrusion molding techniques. In other embodiments, outer pipe  270  and insulating spaces  275 ,  265 ,  255 , and  245  are formed separate from inner pipe  230  and are then later attached to inner pipe  230 . 
         [0033]      FIG. 4B  shows a perspective view of pipe section  210  of  FIG. 4A  with a puncture  212  that breaches exterior pipe  270 . In particular, puncture  212  breaches sub-spaces  275   a ,  275   b , and  275   c  of insulating space  275 , but has not breached pipe  260  or other sub-spaces within insulating space  275 . Therefore, in this example, other sub-spaces of insulating space  275 , insulating space  265  (e.g., sub-spaces  265   a ,  265   b ,  265   c  and  265   d ), insulating space  255 , and insulating space  245  still maintain a vacuum and provide insulation in the region of puncture  212 . Since puncture  212  has only compromised external pipe  270  and sub-spaces  275   a ,  275   b , and  275  of insulating space  275 , it may not be necessary to replace pipe section  210  since inner pipe  230  may still be sufficiently insulated. 
         [0034]    Since each sub-space within each insulating space may have an individual vacuum, a non-catastrophic puncture (e.g., puncture  212 ) may not compromise the insulation of pipe section  210 . Further, pipe section  210  may tolerate a certain number of chamber failures over a certain distance and still maintain sufficient insulation of inner pipe  230 . 
         [0035]      FIG. 5  shows a cross-section through one exemplary embodiment of a pipe joint  320 . Pipe joint  320  may, for example, represent pipe joint  20  of  FIG. 2A . Pipe joint  320  is shown with three concentric pipes  350 ,  340 , and  330  that form insulating spaces  345  and  335  therebetween. Insulating spaces  345  and  335  are each subdivided into sub-spaces by walls  348  and  338 , respectively. 
         [0036]    Outer pipe  350  may be made of thicker material to increase puncture resistance; however, pipes  350 ,  340 , and  330  may vary in thickness without departing from the scope hereof. Each sub-space of insulating spaces  335  and  345  may contain a vacuum to increase insulation properties. Since each sub-space may be individually sealed, one or more punctures to outer pipe  350  may not compromise insulation of inner pipe  330 . 
         [0037]    Concentric joint pipes  340 ,  350 , and  360  have diameters D 5 , D 6 , and D 7 , respectively. The inner diameter D 5  of inner pipe  330  allows pipe section  210  to fit therein. In one example, pipe section  210  and joint  320  fit together snugly; force and/or adhesive, for example, may be used to facilitate joining pipe section  210  and pipe joint  320 . 
         [0038]      FIG. 6A  shows one exemplary embodiment of a pipe section  410  with female  412  and male  414  inter-connecting ends.  FIG. 6B  shows pipe section  410  inverted for clarity of illustration of male end  414 .  FIGS. 6A and 6B  are best viewed together with the following description. 
         [0039]    Female end  412  is shown with a female thread  416 , and male end  414  is shown with a male thread  418 .  FIG. 7  shows multiple pipe sections  410  (labeled  410 ( 1 ) and  410 ( 2 ), respectively) connected together by threads  416 ,  418 . When so connected, surface  420  and surface  424  of female end  412  ( FIG. 6A ) meets surface  422  and surface  426  of male end  414  ( FIG. 6B ), respectively, such that inner pipe  428  allows unimpeded fluid flow between pipe sections. Female thread  416  may, for example, be formed on an inner wall of an outer pipe (e.g., outer pipe  270 ,  FIG. 4A ) of a pipe section (e.g., pipe section  210 ), or may be formed on an inner pipe (e.g., inner pipe  260 ,  FIG. 4A ) such as to include insulation (e.g., insulation space  275 ) around female tread  416 . Male thread  418  may be formed upon an external wall of an inner pipe (e.g., inner pipe  260 ,  FIG. 4A ) such as to include insulation (e.g., insulating spaces  265 ,  255 ,  245 ) between male thread  418  and inner pipe  428 . Thus, when connected ( FIG. 7 ), the insulation properties of multiple pipe sections  410  may be continuous. Adhesive may be used to on threads  418  and/or threads  416  to ensure pipe sections  410  remain connected. 
         [0040]    Changes may be made in the above systems and methods without departing from the scope hereof. It should thus be noted that the matter contained in the above description and/or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.