Abstract:
A floating stuffing box is disclosed which prevents leakage caused by oscillation of the valve stem compressing packing material by instead allowing for movement of the ball within the socket of the base wall as lateral movement of the base.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority to provisional application Ser. No. 60/176,270, filed Jan. 14, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to a stuffing box valve assembly and in particular to a floating stuffing box assembly which prevents oscillation of the valve stem from deforming the packing and causing leaks.  
           [0004]    2. Background  
           [0005]    In the past, packing gland assemblies have been designed to allow rotational movement of the stem within the body while preventing bypass of fluids along the stem through the body. Problems develop, however, when the movement of the stem is not merely rotational, but also involves an oscillation or bending of the stem causing the packing on one side of the stem to be compressed and relieving the pressure on the packing on the opposite side of the stem allowing leaking by the stem to occur. If this oscillation is continued, the packing will fail and leakage will occur along the stem.  
         SUMMARY AND OBJECTS OF THE INVENTION  
         [0006]    It is an object of some embodiments of the present invention to provide a floating stuffing box assembly which permits some oscillation of the valve stem to occur without damaging the packing around the stem.  
           [0007]    The invention comprises two main features which work together to implement the technology. The first feature is a packing gland body having a spherical end which is held in place in a base by a retainer. The base has a socket formed within it which corresponds to the shape of the ball on the end of the packing gland body. The ball and socket relationship allows the packing gland to move within the base without causing added pressure to be placed upon the packing surrounding the valve stem. Within the ball of the gland body is a guide bushing which forces the base to move laterally when the stem oscillates. This lateral movement is the second feature.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    In order that the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention briefly depicted above will be rendered by reference to a specific embodiment thereof which is illustrated in the appended drawings. With the understanding that these drawings depict only a typical embodiment of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
         [0009]    [0009]FIG. 1 is a cross-sectional elevational view of one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.  
         [0011]    As seen in FIG. 1, one embodiment of the present invention utilizes a ball and socket arrangement to obviate the stresses on the packing around the valve stem when the valve stem oscillates. The valve assembly consists of a packing gland body  10  having a spherical portion  12  and an upper L-shaped portion  14 . Located within packing gland body  10  is a guide bearing  16 , packing  18 , a lateraling  20 , three additional rings of packing  22 , a guide bearing  24 , and at the very top of the packing gland a gland follower  26 . The bearings and packing allow for rotational movement of the valve stem  28  within packing gland body  10 . It will be appreciated that valve stem  28  can also be a shaft or stem going to equipment.  
         [0012]    To maintain pressure upon the packing, bearings, lantern ring, gland follower  26  is biased in a downward direction by a Belleville spring  30 , stud  32  and nut  34 . Nut  34  compresses Belleville spring  30  thereby urging gland follower  26  downward to apply pressure to the packing and guide bearings beneath the gland follower within packing gland body  10 .  
         [0013]    Packing gland body  10  is held to a base  36  by a retainer  38 . Retainer  38  is bolted to base  36  to retain packing gland body  10 . “O” rings  40  are located about the ball-shaped portion of the packing gland to prevent the flow of fluid through the space between the ball and socket. In the preferred embodiment illustrated in FIG. 1, four “O” rings are provided for this purpose. A guide bearing  42  is also located within the ball-shaped portion of the packing gland to guide the lateral movement of the packing gland body  10  and base  36  during rotational movement.  
         [0014]    It will be appreciated that gaskets, “O” rings, seals, and the use of materials such as PTFE as is known in the industry will be utilized during the construction of the elements of the base to provide additional protection from leakage. Base  36  is retained against a base plate  44  by a bolt  46  which passes through a pressure clamp  48  which is L-shaped. Bolt  46  passes through pressure clamp  48  and base plate  44  and penetrates into equipment  50 . A gasket  52  may be placed in between the pressure clamp and the base plate. Additional leakage protection is provided by concentric “O” rings  52  to prevent leakage around the base of the valve assembly. Additional protection is provided by applying positive pressure through a purge valve  54  into lantern ring  20 . The pressure is regulated such that it will overcome any pressure from fluid attempting to bypass lantern ring  20 . As a result, a stream of air will be introduced into the flow of fluid instead of fluid exiting the valve assembly. A similar system is used for purge valve  56  at the low end of the valve assembly.