Patent Publication Number: US-2021190245-A1

Title: Ultra-compact tube or pipe coupling for vacuum, liquid or gas

Description:
The United States Government may have certain rights to this invention under Management and Operating Contract No. DE-AC05-06OR23177 from the Department of Energy. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to pipe or tube couplings, and more specifically the creation of a secure pipe or tube coupling in an area that has limited radial space. 
     BACKGROUND 
     In terms of space, the most efficient conventional coupling for connecting two tubes or pipes is butt welding. Other conventional pipe coupling methods include soldering or brazed socket couplings. Epoxy or other adhesive can also be used in a socket type application. All of these are substantially permanent coupling methods that require significant effort to remove and remake the connections. 
     However, in many cases a piping system must be assembled without welding or brazing, such as in those systems in which the coupling must be broken down at intervals during operation of the system. In this situation, a permanent coupling method such as welding would not permit a routine breaking down and reassembly of the coupling. 
     Additionally, conventional flanged coupling systems for pipes or tubes, require significant radial space to allow for bolts or clamps. Thus flanged piping systems are unusable in many systems in which there is limited radial space for bolts or clamps around the pipe, such as beam pipes for physics experiments, which require thin wall beam pipes. Each beam pipe must hide within a narrow cone so as not to impact the experimental results by blocking the path of particles of interest or impeding particles that need to pass by unaffected. 
     Accordingly, there is a need for a tube or pipe coupling that can be easily disassembled and remade without causing significant process downtime, requires minimal radial space beyond the outer diameter of the pipe, and can effectively seal against leaking of vacuum, liquid, or gas. Such a tube or pipe coupling would be useful for allowing for maximum internal passageway for beam pipes that must pass through hardware having narrow apertures and close clearance to the apertures. Such a tube or pipe coupling would also be beneficial in other applications that require minimal radial space beyond the outer diameter of the pipe, including cryogenic lines and RF waveguides 
     OBJECTS AND ADVANTAGES OF THE INVENTION 
     The object of the present invention is to provide a pipe coupling system that separates the functions of compressing the seal material and holding the flange system secure. 
     A second object is to provide a pipe coupling system that is compact, requiring little space beyond the outer diameter of the pipe. 
     A further object is to provide a pipe coupling system that can be easily disassembled and reassembled. 
     Another object is to provide a pipe coupling system that effectively seals against leaking of vacuum, liquid, or gas. 
     These and other objects and advantages of the present invention will be understood by reading the following description along with reference to the drawings. 
     SUMMARY OF THE INVENTION 
     The present invention is a pipe coupling system including a pair of tubular flange halves and a plurality of clamp segments. A seal resides in a groove on the flange face. The tube mating ends are secured to the pipe or tubing. The flange halves are then drawn together and the seal is compressed. The clamp segments are placed around the periphery of the joined flanges. The pipe coupling system advantageously separates the functions of squeezing the seal from tightening the flanges, minimizes the total space required for achieving a seal, is easily disassembled and reassembled without causing significant process downtime, minimizes the radial space needed beyond the outer diameter of the pipe, and effectively seals against leakage of vacuum, liquid, or gas. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Reference is made herein to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a sectional view of an assembled pipe coupling system according to the invention. 
         FIG. 2  is a sectional view of the pipe coupling system with a temporary seal compression tool. 
         FIG. 3  is a side elevation view of two flange halves used in the pipe coupling system of the present invention. 
         FIG. 4  is an end view of a four segment clamp for securing the pipe coupler to a pipe or tube. 
         FIG. 5  is a sectional view of a clamp segment taken along line  5 - 5  of  FIG. 4 . 
         FIG. 6  is an end view of the flanged end of the male flange half of a pipe coupler according to the invention. 
         FIG. 7  is an end view of the flanged end of the female flange half of a pipe coupler according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Conventional flange systems typically use clamps or bolts to both squeeze a seal and to secure two flanges for pressure and mechanical loads. In the current invention, the functions of compressing the seal material and holding the flange system secure have been separated. The pipe coupling system of the invention advantageously requires little additional radial space beyond the tube outside diameter (OD). 
     With reference to  FIG. 1 , a pipe coupling system  20  according to the invention includes two pipe couplers  22 , each coupler  22  having two tubular flange halves, including a male flange half  24  and a female flange half  26 . Each flange half includes a flanged end  28  and a tube mating end  32 . 
     Referring to  FIG. 3 , the male flange half  24  preferably includes a leg  36  thereon and the female flange half  26  includes a notch  38  to receive the leg of the male flange half when the two are drawn together. Male flange half  24  includes a seal groove  40  for insertion of a seal  42  therein. 
     Referring to  FIG. 1 , the flanged ends  28  each include a flange face  43 . Two or more clamp segments  44  are installed around the mated flanges  24  and  26 . Each clamp segment  44  includes a load surface  48  and an outer groove  49 . The clamp segments  44  are secured with an elongated fastening device  50 . The elongated fastening device  50  is preferably wire, string, or similar elongated material that is preferably wrapped multiple times around the outer groove  49  of the clamp segments  44  similar to a bobbin of thread and knotted off. 
     To operate the invention, the tube mating ends  32  of each flange are cleaned and attached to the adjacent tube ends  45  via welding or brazing, or the tube ends  45  can be machined to create integral flange halves on the tube ends. 
     Referring to  FIG. 2 , a sealing tool  52  for compression of the seal  42  is temporarily attached to each tube assembly and the pipe couplers  22  and tube ends  45  tightly together, between mating flange faces  43 . Seals can be O-rings or of any shape to fill the seal grooves  40 . The seals can be constructed of rubber, plastic, or a deformable metal such as indium. For an indium seal the indium is squeezed into the seal groove  40 . In the embodiment shown in  FIG. 2 , the sealing tool  52  includes two split clamps  54  affixed to the tubes  56 , a seal compression rod  58 , and a nut  60  tightened to each end of the seal compression rod  58 . 
     With reference to  FIG. 3 , the flange halves  24  and  26  include a flange angle FA. The flange angle FA is preferably less than 15 degrees in order to maintain the desired compression of the seal  42  by the clamp segments  44 . After initial compression by the sealing tool, the clamp segments  44  require only a few thousandths of an inch of radial draw to clamp the assembly. 
     Flange portion  62  includes an optimal width WF that is application dependent and can be calculated from the thickness t of the tubes  56  and the height HF of the flange portions  62 . The height of the flanges  62  is preferably set to approximately the thickness. The width WF of the flange portion  62  is preferably 2 to 10 t. 
     With reference to  FIG. 4 , there is shown an exemplary pipe coupling  22  having four clamp segments  44  each including an arcuate inner periphery  66  at the innermost extent of the flange gap  64 , an arcuate outer periphery  68 , and an arcuate surface  70  on the outer groove  49 . 
     Referring to  FIG. 5 , each clamp segment  44  preferably includes a mouth  74  with a tolerance of +0.000, −0.003 inch. The tolerance insures that the clamp segment  44  will fit over the mated flanges of the pipe coupler  22  and, when tightened by the elongated fastening device  50 , will further compress the flange halves toward one another, lock the faces of the flange halves together, and further compress the seal. Flange gap  64  includes sidewalls  73  that are substantially the same angle as the flange angle  61  (see  FIG. 3 ) of the flanges. 
     With reference to  FIG. 6 , the male flange half  24  includes the leg  36 , the seal groove  40 , and the flange face  43 . As shown in  FIG. 7 , female flange half  26  includes the notch  38  to receive the leg of the male flange half when the two are drawn together. Male and female flange halves will each include an opening  76  having an inner diameter ID substantially matching the inner diameter of the tube it is affixed to. Flange half  24  will include a seal  42  (see  FIG. 3 ) within the seal groove  40  when the two flanged ends are drawn together. 
     The pipe coupling system  20  according to the invention advantageously separates the functions of squeezing the seal from the tightening the flanges, minimizes the total space required for achieving a seal without requiring welding or brazing, is easily disassembled and reassembled without causing significant process downtime, minimizes the radial space needed beyond the outer diameter of the pipe, and effectively seals against leakage of vacuum, liquid, or gas. Flanges on either end can be same or different materials, and they can be hard plastics, glass or metal. 
     Seals can be constructed of rubber, metal O-rings, C-rings, or soft metal like indium. The groove must match the selected seal profile. Depending on the pressure rating and loads on the piping system, the increase in outside diameter (OD) of the system can be as small as or smaller than 3× the wall thickness of the tube or pipes involved. If the system can allow for reduced flow area the outside diameter of the clamped area can be equal to the OD of the attached tubes or pipes. The flange geometry is chosen to require low hoop load restraint requirements on the securing system. This is accomplished by choosing the slope of the flange to be nearly perpendicular to the axis of the pipe/tube, most preferably no greater than 15 degrees from perpendicular to the axis of the pipe/tube. 
     The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.