Patent Publication Number: US-2007096402-A1

Title: Reduced contact area gasket

Description:
FIELD OF THE INVENTION  
      The present invention relates to a reduced contact area gasket. More particularly, the present invention relates to a reduced contact area gasket having inwardly extending recesses from an outer perimeter of the gasket that facilitate installation of the gasket between flanges. Still more particularly, the present invention relates to a sealing system having a reduced contact area gasket disposed between a pair of flanges.  
     BACKGROUND OF THE INVENTION  
      Gaskets are used to provide a seal between mating flanges in piping systems, on apparatus having mating flanges, and in numerous other applications requiring seals. Low seating stresses (that is, the stress required to deform the gasket to the flange surfaces to provide the seal) are often preferred for certain sealing applications. Reduced contact area gaskets require a reduced seating stress to provide a good seal. However, several problems exist with conventional reduced contact area gaskets.  
      One problem with conventional reduced contact area gaskets is that the fastener holes in the gasket are spaced inwardly from an outer perimeter of the gasket. Therefore, all fasteners must be removed from between the mating flanges prior to installing the gasket. The gasket must then be properly positioned such that the fastener holes in gasket are aligned with the fastener holes in the gaskets. Properly positioning the gasket often proves to be an awkward task, as well as time consuming. Thus, a need exists for a reduced contact area gasket that is quickly located between the mating flanges.  
      Another problem with existing reduced contact area gaskets is that the gasket is awkward to handle when being installed between mating flanges, particularly because the gasket does not extend beyond the outer diameter of the mating flanges. The gasket must be held between the mating flanges such that the fastener holes may be aligned. The space between the faces of the mating flanges is often small, such that holding the gasket in the space is difficult. Thus, a need exists for a reduced contact area that is easily handled to facilitate gasket installation.  
      Still another problem with existing reduced contact area gaskets is that when a gasket needs to be replaced there is no quick and easy way to ascertain information about the current gasket to facilitate its replacement. Research must often be conducted to obtain information about the proper gasket to be used, which often requires investigation of the specifications of the piping system or apparatus in which the gasket is to be used to determine the proper replacement. Alternatively, the gasket to be replaced can be removed to determine if gasket identifying indicia, such as the gasket material and size, is marked on the gasket. Thus, a need exists for a reduced contact area gasket that facilitates gasket identification and replacement.  
      Examples of existing reduced contact area gaskets are disclosed in U.S. Pat. No. 5,362,115 to Carr; U.S. Pat. No. 6,682,081 to Burton et al.; and U.S. Pat. No. 6,869,081 to Jenco, the entire disclosures of each of which are hereby incorporated by reference.  
      Therefore, a need exists for improved reduced contact area gaskets.  
     SUMMARY OF THE INVENTION  
      Accordingly, it is an objective of the present invention to provide a gasket having a reduced contact area, thereby reducing the seating stress and preventing damage to the gasket and flanges during installation.  
      Accordingly, another objective of the present invention is to provide a reduced contact area gasket that is easily disposed between mating flanges.  
      Accordingly, another objective of the present invention is to provide a reduced contact area gasket that is easily disposed between mating flanges already connected by a fastener.  
      Accordingly, still another objective of the present invention is to provide a reduced contact area gasket that is easily identifiable to facilitate replacement thereof.  
      The foregoing objectives are basically attained by providing a reduced contact area gasket that is adapted to be disposed between first and second flanges in a piping system. The reduced area gasket has an outer portion having a first outer perimeter and a first inner perimeter. At least two recesses extend inwardly from the outer perimeter. Each of the at least two recesses is adapted to receive a fastener that secures the first and second flanges between which the reduced contact area gasket is adapted to be disposed. An inner portion of the reduced contact area gasket has a second inner perimeter that defines an aperture therethrough and a second outer perimeter. The at least two recesses are connected to the second outer perimeter. At least two cutout portions extend from a first surface to a second opposite surface of the reduced contact area gasket.  
      The foregoing objectives are also basically attained by providing a sealing system, which includes a reduced contact area gasket disposed between first and second flanges of a piping system. The second flange is secured to the first flange with at least two fasteners. The reduced contact area gasket has an outer portion having a first outer perimeter and a first inner perimeter. At least two recesses extend inwardly from the outer perimeter and are adapted to receive the at least two fasteners. One of the at least two recesses is adapted to receive one of the two fasteners when the fastener is disposed between the first and second flanges. An inner portion of the reduced contact area gasket has a second inner perimeter defining an aperture therethrough and a second outer perimeter. The at least two recesses are connected to the second outer perimeter. At least two cutout portions extend from a first surface to a second opposite surface of the reduced contact area gasket.  
      Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Referring now to the drawings that form a part of the original disclosure:  
       FIG. 1  is a side elevational view of a reduced contact area gasket disposed between first and second flanges;  
       FIG. 2  is a top plan view of a reduced contact area gasket having four recesses and four cutout portions according to a first embodiment of the present invention;  
       FIG. 3  is a side elevational view of the reduced contact area gasket of  FIG. 2 ;  
       FIG. 4  is a side elevational view in section of the reduced contact gasket along line  4 - 4  of  FIG. 2 ;  
       FIG. 5  is a top plan view of a reduced gasket area having eight recesses and eight cutout portions according to a second embodiment of the present invention in which the recesses are connected to an inner portion of the gasket by a connecting arm; and  
       FIG. 6  is a top plan view of a reduced area gasket having eight recesses and eight cutout portions according to a third exemplary embodiment of the present invention in which the recesses are directly connected to an inner portion of the gasket. 
    
    
      Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
     DETAILED DESCRIPTION OF THE INVENTION  
      As shown in  FIGS. 1-6 , the present invention relates to a reduced contact area gasket  21  adapted to be disposed between first and second flanges  11  and  13  in a piping system. The reduced contact area gasket  21  has an outer portion  31  having a first outer perimeter  33  and a first inner perimeter  35 . At least two recesses  51  and  52  extend inwardly from the first outer perimeter  33 . Each of the at least two recesses  51  and  52  are adapted to receive fasteners  16  and  18  that secure the first and second flanges  11  and  13  between which the reduced contact area gasket  21  is adapted to be disposed. An inner portion  41  of the reduced contact area gasket  21  has a second inner perimeter  45  that defines an aperture  23  therethrough and a second outer perimeter  43 . The at least two recesses  51  and  52  are connected to the second outer perimeter  43 . At least two cutout portions  71  and  72  extend from a first surface  81  to a second surface  83  of the reduced contact area gasket  21 .  
      A first exemplary embodiment of a reduced contact area gasket  21  according to the present invention has four recesses  51 - 54  and four cutout portions  71 - 74 , as shown in  FIG. 2 . A second exemplary embodiment of a reduced contact area gasket  221  of the present invention has eight recesses  51 - 58  and eight cutout portions  71 - 78 , as shown in  FIGS. 5 and 6 . The reduced contact area gasket of the present invention may have any number of recesses and cutout portions suitable for the intended application of the gasket. Preferably, the number of cutout portions  71  corresponds to the number of recesses  51 .  
      The reduced contact area gaskets  21 ,  121  and  221  according to exemplary embodiments of the present invention, as shown in  FIGS. 2-8 , have a first outer portion  31  having a first outer perimeter  33  and a first inner perimeter  35 . Preferably, the first inner perimeter  35  is substantially co-axial to the first outer perimeter  33 . The first outer perimeter  35  extends inwardly to form a recess  51  that corresponds to aligned fastener holes in the mating flanges  11  and  13  between which the reduced contact area gasket  21  is adapted to be disposed. As shown in  FIG. 2 , four recesses  51 - 54  are substantially equidistantly spaced along the first outer perimeter  33 . As shown in  FIGS. 5 and 6 , eight recesses  51 - 58  are substantially equidistantly spaced along the first outer perimeter  33 . Although exemplary embodiments are shown having four and eight recesses, the gasket may have any number of recesses greater than one.  
      An inner portion  41  is connected to the outer portion  31 . The inner portion  41  has a second outer perimeter  43  and a second inner perimeter  45 . The second inner perimeter  45  defines an aperture  23  that is aligned with the apertures in the mating flanges  11  and  13  to create a fluid flowpath therethrough. Preferably, the second inner perimeter  45  is substantially parallel to the second outer perimeter  43 .  
      As shown in  FIGS. 2 and 5 , a connecting arm  61  may connect the inner and outer portions  41  and  31 . Preferably, a connecting arm  61  extends from the first inner perimeter  35  of each recess  51  to the second outer perimeter  43  of the inner portion  41 . Thus, in  FIG. 2 , four connecting arms  61 - 64  connect each of the recesses  51 - 54  to the second outer perimeter  43 . As shown in  FIG. 5 , eight connecting arms  61 - 68  connect each of the recesses  51 - 58  to the second outer perimeter  43 .  
      Alternatively, as shown in  FIG. 6 , the outer portion  41  may be directly connected to the inner portion  31 , such that the first inner perimeter  35  is connected to the second outer perimeter  43  at each recess  51 . Thus, as shown in  FIG. 6 , each of the recesses  51 - 58  is directly connected to the second outer perimeter  43  (that is, there is no connecting arm between the recess and the second outer perimeter).  
      A cutout portion  71  in the reduced contact area gasket reduces the amount of contact area between the first and second surfaces  81  and  83  of the gasket and the first and second flanges  11  and  13 , thereby reducing the seating stress. As shown in  FIG. 4 , the cutout portions extend completely through the gasket  21  from the first surface  81  to the second surface  83 . The cutout portion is defined by the first inner perimeter  35 , the second outer perimeter  43  and adjacent recesses. Thus, as shown in  FIGS. 2 and 5 , cutout portion  71  is defined by the first inner perimeter  35  (including the inner perimeter of the adjacent recesses  51  and  52 ), the second outer perimeter  43  and the adjacent connecting arms  61  and  62 . A cutout portion  71  of  FIG. 6  is defined by the first inner perimeter  35  (including the inner perimeter of the adjacent recesses  51  and  52 ) and the second outer perimeter  43 .  
      At least one tab  91  or  93  extends outwardly from the first outer perimeter  33 , as shown in  FIGS. 2, 5  and  6 . Preferably, the tab  91  is marked with indicia identifying the gasket, such as the size and material of the gasket, thereby facilitating replacement of the gasket when necessary. Furthermore, the tab  91  is a convenient handle during gasket installation because the tab extends beyond the outer diameter of the mating flanges  11  and  13 , as shown in  FIG. 1 . By extending beyond the outer diameter of the mating flanges, identifying indicia marked on the tab is easily readable while the gasket is installed between the mating flanges, thereby preventing the flanges from having to be disconnected to obtain information about the gasket. Preferably, the reduced contact area gasket has first and second tabs  91  and  93  that extend in substantially opposite directions, as shown in  FIGS. 2, 5  and  6 .  
      The reduced contact area gasket  21 ,  121  and  221  according to exemplary embodiments of the present invention is preferably unitarily formed as a single piece. The reduced contact area gasket may be used in any suitable application, including between metallic and nonmetallic flanges of piping systems and apparatuses. The reduced contact area gasket is particularly useful in chemical, pulp and paper, food and beverage and other general industrial applications. The gasket may be made of any material suitable for the intended application, such as, but not limited to, rubber or plastic. Preferably, the reduced contact area gasket is made of polytetrafluoroethylene, which is particularly useful in applications where resistance to highly aggressive chemicals is required.  
      Assembly, Disassembly and Operation  
      The reduced contact area gasket  21  is shown disposed between first and second flanges  11  and  13  in  FIG. 1 , thereby forming a sealing system. The first flange  11  is disposed at an end of a first section of pipe  12  and the second flange  13  is disposed at an end of a second section of pipe  14 . Fasteners  16  and  18  and nuts  17  and  19  secure the flanges  11  and  13  together.  
      To install the reduced contact area gasket, preferably, one fastener  16  secures the first and second flanges  11  and  13  together. A reduced contact area gasket accordingly to an exemplary embodiment of the present invention is inserted between the first and second flanges such that one of the recesses  51  receives the fastener, thereby facilitating proper positioning of the gasket between the flanges. The engaged recess acts as an alignment guide such that proper positioning of the gasket between the mating flanges  11  and  13  is quickly and easily achieved. Because the recesses are open at the outer perimeter  33  of the gasket, all of the fasteners do not need to be removed from the first and second flanges during gasket installation.  
      The tab  91  permits an installer to easily handle the gasket during installation by providing a surface to grip that is not disposed between the mating flanges. Furthermore, the tab  91  prevents an installer from having to reach between the narrow gap between the surfaces of the mating flanges to position the gasket during installation.  
      Once the gasket has been properly positioned such that the gasket recesses are aligned with the fastener holes in the flanges  11  and  13 , the remaining fasteners are inserted and/or tightened. The fasteners are then tightened in the appropriate tightening sequence for the application. The reduced contact area of the gasket with the flanges reduces the required gasket seating stress, thereby substantially preventing gasket and flange damage during gasket installation. Furthermore, the outer portion  31  of the gasket substantially prevents rotation of the flanges  11  and  13  during gasket installation.  
      While advantageous embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined in the appended claims.