Abstract:
A swivel joint for coupling a first conduit to a second conduit includes a swivel bearing comprising a body of fluid. The swivel bearing eliminates the creation and transmission of torsional and shear loads when one or both of the conduits are axially loaded.

Description:
BACKGROUND 
     This invention relates generally to swivel joints, and in particular to swivel bearings for use in swivel joints. 
     Swivel joints are commonly utilized in conduit systems in which conduits connected in end-to-end relationship require relative conduit movement, either in an angular or rotative manner, and where the integrity of the conduit system is to be preserved during such deformation. Conventional swivel joints have incorporated ball and socket arrangements, elastomeric seals, rotative seals and other mechanical devices which permit the interconnected conduits limited relative movement. Conventional swivel joints are commonly used in locations hundreds of feet below the surface of a body of water and the exteriors of the swivel joints are subjected to very high fluid pressure. Furthermore, the interiors of the swivel joints may also be subjected to very high fluid pressures. 
     Conventional swivel joints presently available for use under such adverse conditions have not proven as dependable and rugged as desired. 
     The present invention is directed to overcoming one or more of the limitations of existing swivel joints. 
     SUMMARY 
     According to one embodiment of the present invention, a swivel joint is provided that includes a body coupled to a first conduit, a sleeve coupled to a second conduit adapted to be received by the body, a retaining member coupled to the body, including a counterbore adapted to receive the sleeve, a chamber defined by the sleeve and retaining member, and a body of fluid contained within the chamber. 
     According to another embodiment of the present invention, a method of coupling a first rigid conduit to a second rigid conduit is provided that includes transmitting axial loads between the first and second conduits using a body of fluid. 
     The present embodiments of the invention provide a swivel joint that eliminates the creation and transmission of torsional and shear loads when one or more of the conduits are axially loaded. As a result, the operational life of the swivel joint, as well as the conduits coupled by the swivel joint, is greatly enhanced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view illustrating a first embodiment of a swivel joint. 
     FIG. 2 is a cross-sectional view illustrating a second embodiment of a swivel joint. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1 of the drawings, the reference numeral  10  refers, in general, to a swivel joint according to an embodiment of the invention for coupling a conduit  12  to a conduit  14 . The swivel joint  10  includes a body member  16  defining a central through bore  16   a  and having an annular flange  16   b  formed at one end thereof and surrounding the bore for connecting to the corresponding end of the conduit  12  in any known manner, such as by welding. An enlarged counterbore  16   c  is formed in the other end of the body member  16  for reasons to be described. 
     A sleeve  18  has an annular flange  18 a extending from one end thereof which extends in the counterbore  16   c  of the body member  16  in a sliding fit. A threaded counterbore  18 b is formed in the other end of the sleeve  18 , and a central bore  18 c extends through the length of the sleeve  18 . 
     A retaining member  20  is provided for connecting the sleeve  18  to the body member  16  and includes a counterbore  20   a  for receiving the sleeve  18  and a central bore  20   b . A pair of seal rings  22   a  and  22   b  are provided in two axially-spaced annular grooves, respectively, that are formed in the outer surface of the sleeve  18 . The seal rings  22   a  and  22   b  engage the corresponding inner wall of the retaining member  20  to seal the interface between the sleeve and the retaining member. An annular chamber  24  is defined between the bottom of the counterbore  20   a  of the retaining member  20  and the corresponding end of the sleeve  18 . A seal ring  26  extends in an annular groove formed in the bottom face of the counterbore  20   a  for reasons to be described. A lubricating fluid is disposed in the chamber  24 . A plurality of angularly spaced bolts  28 , two of which are shown in FIG. 1, extend through corresponding openings formed through the retaining member  20  and into corresponding internally threaded openings formed in the body member  16  to fasten the retaining member to the body member with the sleeve  16  captured there between. 
     A portion of a tubular member  30  extends in the bore  20   b  of the retaining member  20  and has a central through bore  30   a . The tubular member  30  has an externally threaded end portion  30   b  that extends in the internally threaded counterbore  18   c  of the sleeve  18  in a threaded engagement. The other end of the tubular member  30  is connected to the corresponding end of the conduit  14  in a conventional manner, such as by welding. A pair of seal rings  34   a  and  34   b  extend in axially-spaced annular grooves formed in the inner surface of the retaining member  20  and engage the outer wall of the tubular member  30  to seal the interface between the retaining member and the tubular member. 
     The bores  16   a ,  18   c  and  30   a  of the body member  16 , the sleeve  18 , and the tubular member  30  respectively, define a continuous bore that extends between, and in an aligned, coaxial relationship with the bores  12   a  and  14   a  of the conduits  12  and  14 . Thus, fluid can pass between the conduits  12  and  14  and through the swivel joint  10 . 
     During operation of the swivel joint  10 , axial loads applied to the second conduit  14  are transmitted to the lubricating fluid provided in the chamber  24  thus eliminating any significant torsional loads on the swivel joint  10 . Therefore, the operational life of the swivel joint  10  is significantly increased. In the event of leakage of any lubricating fluid from the chamber  24 , the O-ring seal  26  prevents metal to metal contact between the end walls  18 e and  20   c  and any seizure of the swivel joint  10 . 
     Referring to FIG. 2 of the drawings, the reference numeral  100  refers, in general, to a swivel joint according to an alternate embodiment of the invention for coupling a conduit  112  to a conduit  114 . The swivel joint  100  includes a body member  116  defining a central through bore  116   a  and having an annular flange  116   b  formed at one end thereof and surrounding the bore for connecting to the corresponding end of the conduit  112  in any known manner, such as by welding. An enlarged counterbore  116   c  is formed in the other end of the body member  116  for reasons to be described. 
     A tubular member  118  defining a central through bore  118   a  has an annular flange  118   b  extending from one end thereof which extends in the counterbore  116   c  of the body member  16  in a sliding fit. The tubular member  118  further includes an annular flange  118   c  extending from an intermediate portion thereof. The other end of the tubular member  118  is connected to the corresponding end of the conduit  14  in a conventional manner, such as by welding. 
     A retaining member  120  is provided for connecting the tubular member  118  to the body member  116  and includes a counterbore  120   a  for receiving the annular flange  118   c  of the tubular member  118  and a bore  120   b  for receiving an end of the tubular member  118 . A pair of seal rings  122  and  124  are provided in two axially-spaced annular grooves, respectively, that are formed in the outer surface of the annular flange  118   c  of the tubular member  118 . The seal rings  122  and  124  engage the corresponding inner wall of the retaining member  120  to seal the interface between the sleeve and the tubular member. A radially inclined annular chamber  125  is defined between the inclined bottom of the counterbore  120   a  of the retaining member  120  and the corresponding inclined end of the annular flange  118   c  of the tubular member  118 . A pair of seal rings  126  and  128  extend in two spaced annular grooves formed in the inclined end of the annular flange  118   c  for reasons to be described. A lubricating fluid is disposed in the chamber  125 . 
     A pair of seal rings  130  and  132  are provided in two axially-spaced annular grooves, respectively, that are formed in the inner surface of the bore  120   b  of the retaining member  120 . The seal rings  130  and  132  engage the corresponding outer surface of the end of the tubular member  118  to seal the interface between the retaining member  120  and the tubular member  118 . 
     A plurality of angularly spaced bolts  134 , two of which are shown in FIG. 2, extend through corresponding openings formed through the retaining member  120  and into corresponding internally threaded openings formed in the body member  116  to fasten the tubular member  118  to the retaining member  120 . 
     The bores  116   a  and  118   a  of the body member  116  and the tubular member  118  respectively, define a continuous bore that extends between, and in an aligned, coaxial relationship with the bores  112   a  and  114   a  of the conduits  112  and  114 . Thus, fluid can pass between the conduits  112  and  114  and through the swivel joint  100 . 
     During operation of the swivel joint  100 , axial loads applied to the second conduit  114  are transmitted to the lubricating fluid provided in the chamber  129  thus eliminating any significant shear or torsional loads on the swivel joint  100 . Therefore, the operational life of the swivel joint  10  is significantly increased. In the event of leakage of any lubricating fluid from the chamber  129 , the O-ring seals  126  and  128  prevent metal to metal contact between the end walls  18   e  and  20   c  and any seizure of the swivel joint  10 . 
     The swivel joints of the present disclosure provide several advantages. For example, the inclusion of a swivel bearing in the form of an annular body of lubricating fluid eliminates the generation of any torsional or shear loads. Furthermore, the addition of resilient members within the chambers housing the lubricating fluid of the swivel bearing prevents seizure of the swivel joints in the event of leakage of the lubricating fluid from the fluid chambers. Therefore, the swivel joints of the present disclosure maximize the useful operational life of conduits while also minimizing the generation of harmful torsional and shear loading conditions on the conduits. 
     It is understood that variations may be made in the foregoing without departing from the scope of the invention. For example, the chambers  24  and  129  may include a plurality of chambers that are axially and/or radially and/or angularly spaced apart in order to receive the lubricating fluid and provide additional axial load bearing capacity. Furthermore, the chambers  24  and  129  may be inclined at any angle relative to the axial direction in order to optimally accommodate axial and/or normal forces. In addition, the lubricating fluid provided in the chambers  24  and  129  may at least partially include gaseous and/or solid materials in order to minimize frictional forces. Although illustrative embodiments of the invention have been shown and described, a wide range of modification, changes and substitution is contemplated in the foregoing disclosure. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.