Abstract:
In accordance with the present invention, there is provided a lie loaded packing assembly for a valve which comprises a valve body defining a passage having a valve stem moveably disposed therein and selectively moveable between open and closed positions. Extending about a portion of the valve stem is a packing. One end of a sleeve of the valve bears axially onto and compresses the packing, with a spigot of the valve being cooperatively engaged to the opposite end of the sleeve. A clamp of the valve is cooperatively engaged to the valve body, with a pair of bolts extending between and being secured to the clamp, the spigot, and a flange member which is itself cooperatively engaged to the spigot. The combination of the bolt, spigot and flange member provide an integral spring construction for the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
       STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT  
       [0002]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     The present invention relates generally to valves, and more particularly to a live loaded packing assembly specifically suited for sealing the valve stem of a valve to the sleeve or passage in which the valve stem normally moves.  
         [0004]     In typical valve construction, a valve stem may undergo a turning or sliding movement, or a combination of both movements, within its sleeve during the process of the valve moving between its open and closed configurations. In this regard, the sealing of the stem must be adequate to contend with such movement, while at the same time ensuring maintenance of fluid tightness against the pressure of the fluid in the valve. A widely used type of stem sealing is a compression packing in which a gland, which may be bolted or threaded, applies a compressive force to a soft compression packing in a stuffer box surrounding a portion of the length of the stem. The resulting radial pressure of the packing onto the stem provides the desired seal so long as the radial pressure exceeds the pressure of fluid in the valve.  
         [0005]     In certain valve configurations, compression may be applied to the packing through the use of packing bolts which are each attached at one end to a clamp around the valve body, and at their other end to a spigot, a flange or other projection bearing on, integral with or attached to the gland or sleeve which bears onto the packing. In this particular arrangement, the tightening of the bolts increases the pressure on the packing, thus facilitating the application of radial pressure onto the stem.  
         [0006]     In other valve configurations, it is known to attach a spring between the nut used to tighten the bolt and the surface of the spigot or flange. Although coil springs may be used, a conventional practice is to use Belleville springs which are essentially formed as a series of dished washers. Such springs have a higher compression rating than a simple coil spring, with the use of the Belleville springs providing a “live-loaded” packing which can automatically compensate for changes that may take place in the packing under operating conditions of the valve, such as high pressures and temperatures. Since the volume of the packing material may reduce under certain operating conditions, the spring pressure compensates for such reduction and maintains the required pressure, thus avoiding potential harmful effects to the sealing of the stem in an unsprung valve which could result from the reduction in the packing material volume. Alternatively, if the packing volume increases (which can happen with certain packing materials), the radial pressure of the stem in an unsprung valve could increase too much, thus possibly causing sticking of the stem. The spring value, however, can accommodate the pressure increase by means of further compression of the springs.  
         [0007]     The “live-loaded” packing construction for a valve described above, while providing a useful amount of self-adjustment to maintain the correct pressure through the packing onto the valve stem, has previously been determined to suffer from certain deficiencies detracting from its overall utility. One such deficiency is the need for longer bolts than would otherwise be required in order to accommodate the springs. The provision of such longer bolts requires sufficient clearance beyond the spigot or gland flange to accommodate such bolts and the corresponding springs, which in turn causes difficulties in fitting a “live-loaded” packing construction to existing valves. This particular deficiency is addressed by the live load valve assembly described in Applicant&#39;s prior U.S. Pat. No. 6,622,987 entitled LIVE LOAD ASSEMBLY FOR VALVE issued Sep. 23, 2003, the disclosure of which is incorporated herein by reference.  
         [0008]     In U.S. Pat. No. 6,622,987, in one specific embodiment of the improved live-loaded packing construction, an integral spring construction is provided by one or more slots in the arms of the spigot, each such slot extending in a generally radial direction along a plane perpendicular to the axis of the sleeve. Due to the inclusion of the slots therein, the arm is effectively divided into branches which can be forced toward each other as a result of the tightening of a bolt that passes through them. The arm branches, in conjunction with the bolt, act as an integral spring that is capable of accommodating changes in the volume of the packing in a similar manner to that described above in relation to the use of the Belleville springs. In this regard, when the nut is tightened on its corresponding bolt, the branches of the associated arms are forced to deflect toward each other, or one may deflect towards the other, thereby maintaining a stored energy load which is transmitted to the packing. As is further described in U.S. Pat. No. 6,622,987, where this integral spring construction is provided by the slots and the arms of the spigot, the depth of each slot (i.e., the distance between the branches that it separates) may be made oversize to facilitate greater ease in its manufacture. In this oversized condition, to ensure that the correct amount of deflection of a branch toward a corresponding branch occurs, one or more appropriately sized washers or spacers can be fitted around the bolt to reside between the branches and thus reduce the slot depth. The maximum amount of branch deflection can thereby be controlled by selectively varying the size and/or number of spacers between the arm branches.  
         [0009]     Though providing improvements over conventional live loaded packing construction, the integral spring construction embodiment described in U.S. Pat. No. 6,622,987 itself suffers from one particular drawback. More particularly, there is a susceptibility in such integral spring construction for an over-torque condition to arise as a result of the branches of each arm being forced too close to each other by the over tightening of the nut on the bolt that passes through them. In this regard, the over tightening the nut as causes one or both of the arm branches to bow or deflect too much toward the other may result in the application of an excessive level of radial pressure onto the valve stem, thus resulting in the sticking of the stem. Though such over-torquing of the nut(s) may be prevented by the placement of the above-described spacers between the branches of each arm in the above-described manner, the fitting of such spacers into the valve is time consuming and cumbersome due to the need to select the appropriate size and number of spacers to prevent an over-flexed condition in the branches from occurring. If such spacers are not used, the tightening of the nuts typically must be facilitated through the use of a torque wrench which is itself time consuming and cumbersome. The present invention, while providing the advantages of the integral spring construction described in U.S. Pat. No. 6,622,987, also eliminates the aforementioned deficiency by providing a live-loaded packing assembly for a valve which is specifically configured prevent the over-torquing condition described above from occurring, yet eliminates the need to use spacers or torque wrenches to tighten the nuts. These and other features and advantages of the present invention will be described in more detail below.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     In accordance with the present invention, there is provided a valve which comprises a valve body defining a passage having a valve stem moveably disposed therein and selectively moveable between open and closed positions. Extending about a portion of the valve stem is a packing. One end of a sleeve of the valve bears axially onto and compresses the packing, with a spigot of the valve being cooperatively engaged to and extending radially outward from the opposite end of the sleeve. A clamp of the valve is cooperatively engaged to the valve body, with at least two bolts extending between and being secured to the clamp, the spigot, and a flange member which is cooperatively engaged to the spigot. More particularly, each of the bolts extends between the clamp, a respective one of a pair of arms which are defined by the spigot, and a respective one of an opposed pair of flange portions which are defined by the flange member and extend angularly and in spaced relation to a corresponding arm of the spigot. The combination of the bolt, spigot and flange member provide an integral spring construction for the valve. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     These, as well as other features of the present invention, will become more apparent upon reference to the drawings wherein:  
         [0012]      FIG. 1  is a cross-sectional view of a live-loaded valve construction in accordance with the present invention;  
         [0013]      FIG. 2  is an exploded view of a portion of the valve construction shown in  FIG. 1 ;  
         [0014]      FIG. 3  is a side-elevational view of the spigot and flange assembly of the valve construction shown in  FIG. 1 ; and  
         [0015]      FIG. 4  is an exploded view of the spigot and flange assembly shown in  FIG. 3 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the present invention only, and not for purposes of limiting the same,  FIG. 1  depicts a valve  10  including a live-loaded packing assembly constructed in accordance with the present invention. The valve  10  includes a body which itself comprises a bonnet  11  having a yoke  12  cooperatively engaged thereto. Extending axially through the bonnet  11  is a central passageway  14 , a portion of which is defined by a tubular sleeve  13  which is inserted into the bonnet  11 . Advanced through the passageway  14  is a valve stem  15 , the movement of which opens and closes the valve  10  in a conventional manner. The lower end of the sleeve  13  (viewed from the perspective shown in  FIG. 1 ) bears on and compresses an annular packing  16  which surrounds and exerts radial pressure on that portion of the stem  15  which passes through the packing  16 . The packing  16  may be any suitable or conventionally used material or construction. Further, the packing  16  may be in the form of a multiplicity of rings of the packing material, and may include a lantern ring through which any leakage of fluid from the valve  10  can be channeled to a safe area instead of leaking to atmosphere.  
         [0017]     In the valve  10 , disposed beneath the packing  16  is an annular fixed ledge or body  17  against which the lower end of the packing  16  bears. Disposed at the upper end of the sleeve  13  is a gland spigot  18 . The spigot  18  comprises an integral pair of arms  19 ,  20  which extend in radially opposed directions from the stem  15 . The spigot  18  also includes a central bore  21  through which the stem  15  passes, as well as a pair of bores  22 ,  23  which are disposed in respective ones of the arms  19 ,  20  adjacent the outer ends thereof. The bores  22 ,  23  are sized and configured to receive respective ones of a pair of packing bolts  24 ,  25 . As seem in  FIG. 4 , the spigot  18  also includes a pair of alignment pins  26 ,  27  which protrude substantially perpendicularly from the generally planar top surface thereof. Pins  26 ,  27  are disposed in close proximity to the central bore  21 , and are separated from each other by an interval of approximately 180°.  
         [0018]     Cooperatively engaged to the spigot  18  is a flange member  50  of the valve  10 . The flange member  50  includes a generally quadrangular (e.g., square) central section  51  having a central bore  52  extending therethrough. Also extending through the central section  51  is a pair of alignment apertures  53 ,  54 . The apertures  53 ,  54  are disposed proximate the central bore  52 , and are also separated from each other at an interval of approximately 180°. Protruding outwardly from respective ones of an opposed pair of sides or faces of the central section  15  is an integral pair of flange portions  55 ,  56 . As seen in  FIGS. 1, 3  and  4 , the flange portions  55 ,  56  do not extend perpendicularly from the corresponding vertical sides or faces of the central section  51 , but rather are slightly angled relative thereto. As best seen in  FIG. 4 , the angular elevation A of each flange portion  55 ,  56  relative to the central section  51  is typically in the range of from about 2° to about 6°, and is preferably about 4°. Additionally, the thickness of each flange portion  55 ,  56  is typically in the range of about ⅛ inch to about ⅜ inches, and is preferably about ¼ inch. Disposed within and extending through the flange portion  55  in relative close proximity to the outer, distal end thereof is a bore  57 . Similarly, disposed within and extending through the flange portion  56  in relative close proximity to the outer, distal end thereof is a bore  58 .  
         [0019]     In the valve  10 , the engagement of the flange member  50  to the spigot  18  is facilitated by advancing the pins  26 ,  27  into respective ones of the apertures  53 ,  54 . In this respect, the apertures  53 ,  54  have configurations which are complimentary to those of the pins  26 ,  27 , the spacing/alignment of the apertures  53 ,  54  relative to each other allowing for the advancement of the pins  26 ,  27  thereinto. The receipt of the pins  26 ,  27  into respective ones of the apertures  53 ,  54  effectively coaxially aligns the central bore  21  of the spigot  18  with the central bore  52  within the central section  51  of the flange member  50 . Similarly, the bores  22 ,  23  of the spigot  18  are coaxially aligned with respective ones of the bores  57 ,  58  disposed within the flange portions  55 ,  56  of the flange member  50 . The central section  51  of the flange member  50  is abutted directly against the generally planar top surface of the spigot  18 . However, since the flange portions  55 ,  56  are angularly oriented as described above, the abutment of the central section  51  against the spigot  18  results in the formation of a pair of slots  59 ,  60  which are defined between the upper surface of the spigot  18  and the lower surfaces of respective ones of the flange portions  55 ,  56 . More particularly, as seen in  FIG. 1 , the slot  59  is located between the arm  19  and the flange portion  55 , with the slot  60  being located between the arm  20  and the flange portion  56 .  
         [0020]     In addition to being advanced between the bores  22 ,  23 , the packing bolts  24 ,  25  are further advanced through respective ones of the bores  57 ,  58  of the flange member  50  in the manner shown in  FIG. 1 . Threadably engaged to respective ones of the externally threaded upper end portions of the packing bolts  24 ,  25  is a pair of nuts  28 ,  29 . The opposite, lower end portion of each bolt  24 ,  25  is enlarged and bored to receive of a respective one of a pair of clamping bolts  30 ,  31  in the manner shown in  FIGS. 1 and 2 . In the valve  10 , clamping is achieved by the engagement of a split yoke clamp  32 ,  33  to the valve yoke  12  and bonnet  11 . The yoke  12  includes a lower portion  12 A which is annular and defines a radially outwardly extending, angled flange portion  35  at its lower extremity. The bonnet  11  has a stepped upper profile including an annular upper portion  36  which fits within the lower portion  12 A of the yoke  12 . The flange portion  35  of the yoke  12  sits upon a generally planar step  37  defined by the bonnet  11 . More particularly, the step  37  is defined above as an angled, radially outwardly extending flange portion  38  of the bonnet  11  which transitions to annular neck portion  39  of the bonnet  11 . The flange portions  35 ,  38  are retained within a corresponding annular recess  41  collectively defined by the clamp  32 ,  33 , the clamp  32 ,  33  thereby holding the valve body parts together. As will be recognized, the clamp  32 ,  33  is tightened by tightening the nuts  34  threadably engaged to the externally threaded end portions of the clamping bolts  30 ,  31  as shown in  FIG. 2 .  
         [0021]     As explained above, in addition to being advanced between the bores  22 ,  23  of the spigot  18 , the packing bolts  24 ,  25  are further advanced through respective ones of the bores  57 ,  58  of the flange member  50 , with the nuts  28 ,  29  being threadably engaged to respective ones of the externally threaded upper end portions of the packing bolts  24 ,  25 . The tightening of the nuts  28 ,  29  on the bolts  24 ,  25  effectively forces or flexes the flange portions  55 ,  56  toward respective ones of the arms  19 ,  20 , and further causes the central section  51  to act against the spigot  18  in a manner facilitating the transmission of force to the packing  16  via the arms  19 ,  20  and sleeve  13 . As explained above, such force, when transmitted to the packing  16 , causes the packing  16  to radially engage the stem  15  extending therethrough.  
         [0022]     Advantageously, the configuration of the spigot  18  and flange member  50  effectively prevents any over-torquing of the nuts  28 ,  29  since a natural limit is provided when the flange portions  55 ,  56  of the flange member  50  go flat. When the flange portions  55 ,  56  go flat, they engage the generally planar top surface of the spigot  18 , and more particularly the generally planar top surfaces of respective ones of the arms  19 ,  20  of the spigot  18 . Those of ordinary skill in the art will recognize that the angle A (and hence the sizes of the slots  59 ,  60 ) and/or the thickness of each of the flange portions  55 ,  56  may be increased or decreased depending on the desired stress level which is to result from the tightening of the nuts  28 ,  29  as causes the flange portions  55 ,  56  to go flat. In the arrangement shown in  FIG. 1  (i.e., each angle A is about 4° with the thickness of each of the flange portions  55 ,  56  being about ½ inch), the flattening of the flange portions  55 ,  56  will occur upon the application of approximately fifty foot pounds of torque to each of the nuts  28 ,  29 . As indicated above, such angles A and/or the thicknesses of the flange portions may be tuned (increased or decreased) as needed to satisfy the requirements of a particular application. The over-torquing prevention provided by the combination/assembly of the spigot  18  and flange member  50  is achieved without the need to resort to the use of a torque wrench to tighten the nuts  28 ,  29  or to insert spacers into the slots  59 ,  60 .  
         [0023]     Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only one embodiment of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.