Abstract:
A method and apparatus facilitates coupling a pressure vessel first mating surface to a second mating surface. The method comprises inserting a seal assembly into a groove defined in the first mating surfaces such that a portion of the seal assembly extends outwardly from the first mating surface, positioning the second mating surface in close proximity to the first mating surface such that the portion of the seal assembly extending outwardly from the first mating surface is received within a groove defined in the second mating surface, and such that the seal assembly facilitates reducing fluid leakage between the first and second mating surfaces.

Description:
BACKGROUND OF THE INVENTION 
     This application relates generally to bolted joints and, more particularly, to methods and apparatus for coupling high pressure bolted joints. 
     Within known power generation systems, leakage from a high pressure region through a bolted joint to a region of lower pressure may adversely affect the performance of the system. For example, the steam flow path in a steam turbine engine and the gas flow path in a gas flow turbine engine may be at a much higher pressure than a pressure of the surrounding ambient flow. Leakage of the steam and gas from the respective turbine engine to areas of lower pressure may be detrimental to the performance of either turbine engine. 
     To facilitate reducing leakage from high pressure regions to regions of lower pressure, flanges used with bolted connections are machined until the mating face of each flange is substantially smooth and flat. Moreover, each bolt used with such connections is then torqued such that the bolting force induced to each flange is substantially constant across the mating surface. However, because of the size and complexity of the components being coupled together, machining the flanges to the finish required to prevent leakage may be a difficult and time-consuming task. Moreover, depending on the application, fluids within areas of high pressure may still leak through such connections. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect, a method for positioning a pressure vessel first mating surface adjacent to a second mating surface is provided. The method comprises inserting a seal assembly into a groove defined in the first mating surfaces such that a portion of the seal assembly extends outwardly from the first mating surface, positioning the second mating surface in close proximity to the first mating surface such that the portion of the seal assembly extending outwardly from the first mating surface is received within a groove defined in the second mating surface, and positioning the first mating surface adjacent to the second mating surface such that the seal assembly facilitates reducing fluid leakage between the first and second mating surfaces by creating a tortuous path against leakage. 
     In another aspect, a coupling system for use in pressure vessels is provided. The coupling system includes a first component, a second component, and a sealing assembly. The first component includes a mating surface and a groove defined within the mating surface. The second component includes a mating surface and a groove defined within the mating surface. The second component is positioned adjacent to the first component such that the first and second mating surfaces are substantially flush against each other. The sealing assembly is positioned at least partially within the first component mating surface groove and the second component mating surface groove and extends between the first and second components to facilitate reducing fluid leakage therebetween. 
     In a further aspect, a pressure vessel is provided. The pressure vessel includes a first mating surface, a second mating surface, and a sealing assembly. The first mating surface includes a groove defined therein. The second mating surface includes a groove defined therein. The second mating surface is positioned substantially flush against the first mating surface. The sealing assembly is positioned within the first and second mating surface grooves to facilitate reducing fluid leakage between the first and second mating surfaces. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is schematic illustration of an exemplary coupling system for use with pressurized fluids; 
         FIG. 2  is an alternative embodiment of the coupling system shown in  FIG. 1 ; and 
         FIG. 3  is a further alternative embodiment of the coupling system shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As used herein, the term “pressure vessel” may include any vessel, container, component, or portion thereof, that is designed to contain a pressurized fluid that is at a pressure above that of atmospheric pressure. For example, pressure vessels may include, but are not limited to, turbine casings, turbine shells, steam separators, vavle casings, pipe joints, and/or pipe flanges. The aforementioned examples are intended as exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the terms “pressure vessel”. In addition, as used herein the term “component” may include any object that has been, or may be, manufactured. 
       FIG. 1  is schematic illustration of an exemplary coupling system  10  for use with pressure vessels and pressurized fluids.  FIG. 2  is an alternative embodiment of coupling system  10 .  FIG. 3  is an further alternative embodiment of coupling system  10 . In each embodiment, and as described in more detail below, coupling system  10  facilitates coupling a flanged first component  12  to a flanged second component  14  within a pressure vessel. More specifically, in each exemplary embodiment, the pressure contained by second component  14  is higher than the pressure contained by first component  12 . As such, and as illustrated, in each embodiment, the pressure on the left side of each figure is greater than the pressure on the right side of each figure. Moreover, the pressure may increase as components  12  and  14  are coupled together. 
     In each embodiment, coupling system  10  includes a seal assembly  20  and a plurality of fasteners  22 . Fasteners  22 , as described in more detail below, facilitate mechanically coupling first component  12  to second component  14  such that a flange mating surface  24  of first component  12  is substantially flush along a joint line  25  against a flange mating surface  26  of second component  14 . In the exemplary embodiment, fasteners  22  are threaded nut and bolt assemblies. Alternatively, any fasteners  22  may be any fastener which facilitate coupling first component  12  to second component  14  as described herein, such as, but not limited to, rivets, or screws. 
     In each embodiment, first component  12  and second component  14  include a sealing groove  50  and  52 , respectively, defined therein. More specifically, each groove  50  and  52  extends generally radially inward from each respective mating surface  24  and  26 . In one embodiment, groove  50  and/or  52  substantially circumscribes a respective component  12  or  14 . In an alternative embodiment, a series of grooves  50  and/or  52  are oriented to substantially circumscribe component  12  or  14 , respectively. 
     In each embodiment, grooves  50  and  52  are oriented such that when components  12  and  14  are coupled together via fasteners  22 , grooves  50  and  52  are concentrically offset from one another. More specifically, grooves  50  and  52  are oriented such that only a portion  60  of groove  50  overlaps a portion  62  of groove  52  when components  12  and  14  are coupled together. It should be noted that although grooves  50  are illustrated as being substantially straight in cross-section, grooves  50  may have any cross-sectional shape and can be formed in round or curved component sections to accommodate pipe and casing profiles, for example. 
     Seal assembly  20  includes a seal member  40  and a seal filler  42 . In the exemplary embodiment, seal filler  42  is a caulking wire sealing strip. Alternatively, seal filler  42  may be any seal sealing strip that enables filler  42  to function as described herein. Seal member  40  includes a first end  70 , a second end  72 , and a body  74  extending therebetween. Seal member  40  provides a sealing advantage over known sealing components by creating a torturous flow path which facilitates minimizing fluid flow between components  12  and  14 . 
     In each embodiment, when first component  12  is coupled to second component  14 , seal member first end  70  is positioned within first component groove  50 , seal member second end  72  is positioned within second component groove  52 , and seal body  74  extends between grooves  50  and  52 . More specifically, when components  12  and  14  are coupled together, seal member body  74  extends substantially perpendicularly between component groove portions  60  and  62 , with respect to mating surface  24  and joint line  25 . Moreover, in each embodiment, seal member first end  70  is sized and shaped to extend outwardly from seal member body  74  along a bottom surface  80  of groove  50 . More specifically, when components  12  and  14  are coupled together, seal member first end is pressed substantially flush against groove bottom surface  80  in sealing contact. 
     In each embodiment, after seal member first end  70  is positioned within groove  50 , seal filler  42  is positioned within groove  50  to facilitate securing seal member  70  within groove  50 . Accordingly, in each exemplary embodiment, seal member first end  70  is positioned between seal filler  42  and groove bottom surface  80 . 
     Seal member second end  72  is positioned within groove  52 . Seal member second end  72  is compliant such that when components  12  and  14  are coupled together, second end  72  is positioned in contact against a portion of a wall  86  defining groove  52  such that seal member second end  72  provides sufficient leakage interference within groove  52 , as explained in more detail below. More specifically, and for example, in one embodiment, seal member second end  72  is positioned substantially flush against a bottom surface  84  of groove  52 , as is shown in  FIG. 2 . In another exemplary embodiment, seal member second end  72  is L-shaped and is positioned against groove bottom surface  84  and a side wall  88  defining groove  52 , as is shown in  FIG. 1 . In a further embodiment, seal member second end  72  is a knife edge that extends obliquely from seal member body  74  to contact groove bottom surface  84 , as is shown in  FIG. 3 . In another embodiment, a plating or coating, such as, but not limited to, a copper material or a nickel material, is applied within a portion of groove  52  or  50  to facilitate seating of seal member second end  72  within groove surface  84 . In one embodiment, seal member  40  is fabricated from a material having a higher differential thermal expansion coefficient than components  12  and/or  14  such that seal member  40  expands more than components  12  and/or  14  when system  10  is heated. 
     In each embodiment, when component  12  is coupled to component  14 , the seal/groove interference formed between seal assembly  20  and grooves  50  and  52  creates a labyrinth-type seal that defines a tortuous path for leakage between components  12  and  14 . More specifically, when components  12  and  14  are coupled together, seal assembly  20  extends across joint line  25  and bridges the gap between components  12  and  14 . Thus, when a positive pressure is applied to components  12  and  14 , seal assembly  20  facilitates creating a leakage barrier as seal filler  42  is pressed against seal member  40 . The pressure induced against seal member  40  by seal filler  42  facilitates forcing seal member  40  into sealing contact with groove surface  80 . 
     Moreover, as seal filler  42  is deformed against seal member  40  within groove  50 , the deformation of seal filler  42  facilitates seal assembly  20  effectively reducing fluid leakage through joint line  25  and thus forces fluid leakage entering joint line  25  to attempt to travel through the tortuous fluid path defined by seal member  40  and more particularly, defined by seal member second end  72  and wall  86 . In an alternative embodiment, coupling assembly  10  does not include grooves  50  and  52 , but rather relies on a tongue and groove type arrangement with seal assembly  20 . 
     The above-described coupling assemblies provide a cost-effective and reliable method for facilitating reducing leakage through bolted couplings exposed to high pressure. More specifically, the coupling assemblies include a seal assembly that extends across a joint line, formed between the two coupled components, and into grooves formed within each component. As such, when a positive pressure is induced to the coupling assembly, the seal assembly forms an interference fit with the grooves such that a labyrinth-type seal having a tortuous path for leakage is formed. Accordingly, flange sections of each component can be machined more easily without any complex features. As a result, the coupling assembly facilitates reducing leakage through bolted joints in a cost-effective and reliable manner. 
     Exemplary embodiments of bolted joints and coupling assemblies are described above in detail. The coupling assemblies are not limited to the specific embodiments described herein, but rather, components of each coupling assembly may be utilized independently and separately from other components described herein. For example, each seal assembly component can also be used in combination with other seal assemblies and other coupling assemblies, and is not limited to practice with only components  12  and  14  as described herein. Rather, the present invention can be implemented and utilized in connection with many other joint configurations. Moreover, the present invention can be stacked depending on the application. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.