Abstract:
A stemmed control valve having a housing containing a first packing assembly that is compressively loaded externally of the housing, and a second packing assembly that is independently compressively loaded in a fixed manner internally of the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to valve systems that employ a moving valve stem surrounded by multiple packing sets that are compressed by a moving packing follower. 
         [0003]    2. Description of the Prior Art 
         [0004]    For sake of clarity of comparison and brevity only, and not by way of limitation, the prior art valves and the valves that employ this invention will be described as though the movable stem was disposed vertically. The valves of this invention, like those of the prior art, can be employed in any spatial orientation from a vertical stem (up or down) to a horizontal stem, and any angle there between. 
         [0005]    This invention also applies to moving stem valves in general. For example, this invention applies to an elongate stem that 1) is moved directly along its longitudinal axis to open and close the fluid flow passage of the valve body, 2) is rotated about its longitudinal axis to effect movement along that longitudinal axis to open and close the fluid flow passage of the valve body, e.g., gate type valves, and 3) is rotated about its longitudinal axis to open and close the fluid flow passage of the valve body without movement of the stem along its longitudinal axis, e.g., butterfly, ball, or plug type valves. The various structures for and operations of the foregoing types of stem valves are well known in the art and further description is not necessary to inform the art. 
         [0006]    Again, for sake of clarity of comparison and brevity only, and not by way of limitation, the prior art valves and the valves that employ this invention will be disclosed in detail hereinafter in respect of valves whose stem is moved directly along the longitudinal axis of the stem to open and close the fluid flow passage of the valve body 
         [0007]    Heretofore, valve assemblies using a moving stem carrying a control member to close and open a fluid flow passage in a valve body have employed a packing set surrounding the movable (along the long axis and/or around the long axis) stem with a packing follower pressed onto the top of the packing set to apply a sealing compressive force to the packing and stem. Such assemblies are reliable, but not sufficiently reliable to satisfy the requirements for valves that are to be used in hazardous waste service. 
         [0008]    Hazardous waste service requires double containment of the packing, i.e., more than one packing set around the stem, leak detection, and controlled bleed off of process fluid that manages to by-pass the lower most (primary) packing set. 
         [0009]    Employing at least one additional packing set above the primary packing set does not provide satisfactory double containment service for hazardous waste purposes. This is so because transmitting the packing compression load by way of a movable packing follower at the top of a packing stack containing multiple packing sets does not uniformly transmit the sealing compressive loading force from that packing follower through the upper most packing set to the lower most packing set. Put another way, the friction in the stack of multiple (two or more) packing sets has been found greatly to reduce the compressive load going down the stacked packing sets. This results in one or more of the lower packing sets, particularly the primary packing set, receiving insufficient sealing compression force from the outset. 
         [0010]    Accordingly, it is desirable that there be available a packing system that employs a packing stack of two or more packing sets that at all times from the outset provides adequate sealing compression force to all packing sets in the stack, particularly the primary packing set. 
       SUMMARY OF THE INVENTION 
       [0011]    Pursuant to this invention, there is provided a stem valve system that carries multiple packing assemblies around the valve stem, an upper packing assembly compressed by a packing follower at the top of the upper most packing set in the assembly, and at least one of the lower packing sets in the assembly being compressed independently of the packing follower by way of at least one internal compression member. 
         [0012]    By this invention at least the primary packing assembly can be loaded to a desired compressive load independently of the compressive load imparted by the movable packing follower that acts on a separate packing assembly that is disposed above the primary packing assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows a typical valve assembly that employs a stem that carries a control member for regulating the flow of process fluid through the body of the valve. 
           [0014]      FIG. 2  shows in more detail a prior art valve system useful with the valve assembly of  FIG. 1 , and that employs multiple packing sets with live compressive loading of the upper most packing set using an externally spring biased packing follower. 
           [0015]      FIG. 3  shows one embodiment of a valve system within this invention. 
           [0016]      FIG. 4  shows an enlargement of the medial and distal sections of the packing containment section of the valve system of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  shows valve assembly  1  comprising a flanged valve body  2  having a fluid flow passage  3  there through from its inlet end  4  to its outlet end  5 . A valve mounting housing  6  is fixed to body  2  in a fluid sealed manner. Body  2  carries a plurality of bolts  7  that are adapted to pass through mating apertures in flange  9  of housing  6 . Housing  6  is fixed to body  2  by way of nuts  8  engaging bolts  7  in conventional fashion. Body  2  has an aperture  10  through which moves process fluid control member  11 . 
         [0018]    Member  11  controls the flow of process fluid through passage  3  from fully closed as shown in  FIG. 1  to fully open (not shown) when member  11  is fully retracted into recess  12  of housing  6 . Movement of member  11  is caused by raising or lowering of elongate valve stem  13  up or down. Stem  13  has opposing ends, one of which carries control member  11 , and is surrounded for most of its length by housing  6 . Stem  13  has a longitudinal axis “A.” Apparatus (not shown) is fixed to stem  13  to move it upwardly and/or downwardly. Such apparatus is well known in the art and further description is not necessary to inform the art. 
         [0019]      FIG. 2  shows that body  2  is counter bored to provide lower bore  12  that is sized to receive the entirety of member  11  of  FIG. 1 , and an upper, narrower bore  20  sized to receive and hold the entirety of a packing assembly described hereinafter. Bore  20  has a single, constant transverse cross-sectional width. The lower end (shoulder)  21  of the portion of body  6  that contains bore  20  has internal threads  22  that threadably receive and engage an annular, externally threaded packing nut  23  that surrounds stem  13 . Nut  23  supports the packing assembly disposed there above inside recess  20 . 
         [0020]    Bores  12  and  20  have the same longitudinal axis “B,” and they are aligned with stem axis A. 
         [0021]    Above packing nut  23 , and contiguous therewith, is a first (primary) packing set composed of one or more flexible (woven), annular packing members  24  well known in the art. Annular packing support rings  25  and  26  are disposed on and in contact with the lower and upper ends, respectively, of packing set  24 . 
         [0022]    Above ring  26 , and contiguous there with, is an annular spacer  27  that faces, but is spaced from, a bleed-off orifice  28  which passes through the wall of housing  6 . Spacer  27  allows for the collection outside of housing  6  of process fluid that may by-pass packing set  24 . A bleed-off connector  29  is provided so that conventional fluid collection equipment can be attached to orifice  28  in a fluid communication manner to remove fluid from inside housing  6  if and when needed. 
         [0023]    Above spacer  27 , and contiguous therewith, is an upper packing set  30  composed of one or more conventional annular packing members and having on the lower and upper ends thereof, respectively, annular packing support rings  31  and  32 . 
         [0024]    Ring  32  is in physical contact with a vertically movable annular packing follower  33  which in turn is in physical contact with movable, externally spring biased, annular flange member  34 , all of which surrounds stem  13 . 
         [0025]    Body  6  carries a pair of support extensions  35  that extend laterally from that body beneath member  34 . Extensions  35  carry, by way of pinned clevis  36 , upright shafts  37 . Shafts  37  extend through apertures  38  in member  34  and a substantial distance above member  34 . 
         [0026]    The portion of shaft  37  above the top of member  34  carries a spring support ring  40 . Contiguous with ring  40  is a spring member  41 . Spring  41  can be any conventional spring type, e.g., a coil spring. Contiguous with the top of spring  41  is another annular spring support ring  42 . The upper end  43  of shaft  37  is threaded to receive adjusting nut  44 . It can be seen that springs  41  are carried externally of housing  6 . 
         [0027]    Housing  6  encloses part, e.g., most, of the elongate length of stem  13  along its axis A, such enclosed length being intermediate the opposing ends of stem  13  and being spaced (extended) from the end of stem  13  that carries control member  11 . Thus, distal (upper) end  49  of stem  13  extends externally of housing  6  for coupling to conventional stem moving (reciprocating) apparatus (not shown) well known in the art. 
         [0028]    In operation, after packing nut  23  is in place and the packing assembly between nut  23  and follower  33  is in place inside bore  20 , follower  34  is placed in contact with ring  32  and flange member  34 , while shafts  37  are positioned as shown in  FIG. 2 . With the valve system thus assembled, nuts  44  are rotated about the long axes of shafts  37  to cause nuts  44  to move downwardly to compress springs  41 . The compression of springs  41  causes downward movement of follower  33  which in turn applies a compressive load to the packing system in general, and the upper packing set  30  in particular. The single compressive load thus applied at the top of packing set  30  is relied upon to load both of packing sets  24  and  30  and them against stem  13  in a sealing manner. 
         [0029]    The type of packing loading shown in  FIG. 2  with its external springs that can be adjusted at will while the valve system is in operation is termed “live loading” in the art. 
         [0030]    It has been found that because of the friction in packing sets  24  and  30  the compression loading going down this packing assembly is not uniformly transmitted to primary packing set  30  thereby, at the outset, preventing packing set  30  from receiving the total of the compressive loading needed for good sealing between packing set  30  and stem  13 . This is not desirable, particularly if the valve system is employed in hazardous waste disposal service. 
         [0031]      FIG. 3  shows one embodiment within this invention which employs a valve mounting housing  35  that can be affixed to a valve body (not shown) in the manner of flange  9 , bolts  7 , and nuts  8  of  FIG. 2 . 
         [0032]    Housing  35  is also counter-bored, but in a manner reverse from that of housing  6  in  FIG. 2 , in that first (lowest) bore  36  which is adjacent the valve body (not shown) has a smaller transverse cross-sectional width C than the transverse (lateral) cross-sectional width D of medial counter-bore  37  of housing  35 . Distal (upper) counter-bore  45  in turn has a larger transverse cross-sectional width E than the transverse cross-sectional width D of medial bore  37 . This is better shown by reference to  FIG. 4 . 
         [0033]    When bores C, D, and E are essentially round in their transverse cross-section, which is preferred but not required, widths C, D, and E will be the diameter of each of those bores. The term “diameter” will be used hereinafter for sake of clarity and not in way of restriction as to the scope of the transverse cross-sections useful in this invention. 
         [0034]    As with  FIG. 2 , lower bore  37  is sized in internal dimensions to receive in its entirety a movable, fluid passage control member such as member  11  of  FIG. 1 . 
         [0035]    Similarly, housing  35  encloses part, e.g., most, of the elongate length of stem  13  along its axis A, such enclosed length being intermediate the opposing ends of stem  13  and being spaced (extended) from the end of stem  13  that carries control member  11 . Thus, distal (upper) end  49  of stem  13  extends externally of housing  6  for coupling to conventional stem moving (reciprocating) apparatus (not shown) well known in the art. 
         [0036]    The longitudinal axis A of stem  13  in  FIG. 3  is aligned with the longitudinal axis K of bores  36 ,  37 , and  45  in the same manner as axes A and B of  FIG. 2  are aligned. 
         [0037]    Bore  37  carries above shoulder  38  a first packing assembly. The exemplary assembly shown is the lower, primary packing assembly. This packing assembly contains an annular packing set  39  having annular packing rings  40  and  41  contiguous with its lower and upper ends, respectively, all surrounding stem  13 . Above packing set  39  in this assembly is a spring pack  42  having annular spring support rings  43  and  44  contiguous with its lower and upper ends, respectively. Spring pack  42  can contain one or more springs commonly employed in the art, e.g., coil, wave, belleville, and the like. 
         [0038]    The upper, interior end of bore  37  carries engagement means for applying sealing compression to the packing assembly in bore  37 , and locking in that compression loading. In the example of  FIG. 3  the engagement means is internal threads  46  in threaded portion G. Engaged with threads  46  is an annular compression nut  47  that is carried internally of housing  35  and in physical contact with ring  44  of the primary packing assembly. Contiguous with nut  47  is annular locking nut  48 . Each of nuts  47  and  48  have recesses  50  and  51  spaced apart around the upper periphery thereof which recesses are adapted to receive prongs from a rotational installation tool (not shown). 
         [0039]    Rotation of nut  47  about and along axes A and K moves that member in a direction parallel to the longitudinal axes of stem  13  and bores  36 ,  37 , and  45 , thereby enabling a user of a rotational tool to apply, by way of nut  47 , the desired sealing compressive force directly to the primary packing assembly, i.e., to packing set  39  by way of spring pack  42 . This is in clear distinction to the apparatus of  FIG. 2  wherein the compressive force was applied to lowest packing set  24  only through upper packing set  30  that is intermediate of the packing follower  33  and packing set  24 . Thus, in the inventive arrangement of  FIG. 3 , all of the compressive force needed for good sealing between packing set  39  and stem  13  is reliably applied to that packing set at the outset. 
         [0040]    Rotation of nut  48  about and along axes A and K moves that member in a direction parallel to the longitudinal axes of stem  13  and bores  36 ,  37 , and  45 , thereby enabling a user of a rotational tool to lock nut  47  in place once the desired compressive force has been applied by way of nut  47  and spring(s)  42  to packing set  39 . 
         [0041]    The top end of threads  46  defines the top end of bore  37 , see  FIG. 4 . Above the uppermost thread of threads  46 , counter-bore  45  begins and continues to the top end  52  of housing  35 . 
         [0042]    The packing stack of  FIG. 3  also includes an upper packing assembly that is contiguous with the upper end of the lower packing assembly. In the exemplary packing assembly of this Figure, the lowest portion of the upper packing assembly includes, contiguous with the top of locking nut  48 , a rigid, annular spacer  53  having a circumferential groove  54 . Grooved spacer  53  can be any commonly used member such as a lantern ring. Groove  54 , in the example of  FIG. 3 , faces a fluid conductive orifice  55  that extends fully through the wall of housing  35  to the exterior of that housing. Orifice  55  is capped on the exterior of housing  35  by a connector  56  to which drainage (bleed) equipment (not shown) can be attached. The upper packing assembly also includes a packing set  57  having annular packing rings  58  and  59  contiguous with its lower and upper ends, respectively. Packing set  57  is disposed above and in contact with spacer  53 . In this manner, any process fluid that may escape the flow passage of the valve body into first bore  36  and by-pass packing set  39  can be collected in groove  54  in a sealing manner below packing set  57  and removed in a controlled manner through orifice  55  and connector  56 . 
         [0043]    Contiguous with ring  59  is packing follower  33  of  FIG. 2 . Packing set  57  is live loaded in the manner shown and described in  FIG. 2  using elements  34 - 38  and  40 - 44  of that Figure. 
         [0044]    Thus, it can be seen from  FIG. 3  that the upper (packing gland) portion of housing  35  is composed of an upstanding length F plus threaded portion G that together define medial bore  37  having a diameter D. Medial bore  37  is surmounted by an upstanding length H that defines distal bore  45  that has a diameter E, which is greater than diameter D. 
         [0045]    In operation, packing set  39  and spring  42 , with their associated rings, are placed in medial bore  37  and compression nut  47  rotated on threads  46  to move same downwardly along axes A and K thus compressing spring  42  until packing set  39  is compressed to the desired load thereby sealing packing set  39  in a fluid tight manner to stem  13 . Thereafter, nut  48  is rotated on threads  46  in like manner until its lower surface tightly abuts the upper surface of nut  47  and fully locks nut  47 , spring  42 , and packing set  39  into their desired fixed sealing loading. In this manner the required sealing loading on packing set  39  is assured at the outset by way of members  42  and  47  that are carried internally of valve housing  35 . Thereafter, spacer  53  and packing set  57 , with their associated supporting rings, are installed in bore  45  and live loaded by way of follower  33  and separate, independent, external spring pressure (spring  41  compressed between flange  34  and nut  44 ,  FIG. 2 ) so that the proper sealing loading on packing set  57  is also assured. 
         [0046]    This combination of live loading at least one upper packing set, and independently, internally fixed loading of at least one primary packing set produces uniform sealing loading along the full sealing length of stem  33 . This arrangement produces a sealing result that is far more reliable in its sealing effect and duration than that achieved by transmitting the entire sealing loading from a single, upper follower  33  through a plurality of stacked packing sets  24  and  30 , as shown in  FIG. 2 . 
         [0047]      FIG. 4  shows an enlarged portion of housing  35  of  FIG. 3  to better show the relative relationship and transition between medial bore  37  and distal bore  45 , particularly threaded portion G of the upper end of medial bore  37 . In the example of  FIG. 3 , at the top end  60  of medial bore  37  threads  46  start and continue downwardly along the interior surface of medial bore  37  until sufficient threads  46  have been provided at least to receive the length of both of externally threaded nuts  47  and  48  ( FIG. 3 ), i.e. length G. The inwardly extending, opposing tips  61  and  62  of threads  46  are spaced apart for the same diameter D as the rest of non-threaded medial bore  37   63 . Immediately above medial bore end  60 , distal bore  45  begins and continues to the top end  52  of housing  35 .