Abstract:
A gate valve actuator that utilizes a mounting ring interposed between the valve bonnet and actuator housing to allow the mounting of different sizes and types of gate valve actuators onto a given gate valve and providing rotation with respect thereto is disclosed. A split retainer ring allows the coupling between the actuator and valve bonnet to avoid the use of bolts subject to corrosion and failure. A first embodiment uses a pneumatically operated diaphragm to provide a force for opening the valve. Other embodiments use pneumatically and hydraulically powered pistons. Another embodiment shows the use of multiple springs to augment the closing force.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a pneumatically actuated diaphragm or piston linear gate valve actuator and a hydraulically actuated piston linear gate valve actuator that is operated between a first position in which fluid flows through the valve bore and a second position in which the valve bore is closed. Such valve actuators have a variety of applications in the oil and gas industry. Additionally, an embodiment applicable to a hydraulically actuated gate valve actuator is disclosed.  
           [0003]    Gate valve actuators are used to remotely control the opening and closing of gate valves commonly used in the oil and gas industry. Remote control of these valves is often desirable due to safety concerns or relative inaccessibility of the valve for manual operation. Additionally, when such gate valve actuators are used, they may be used to control and operate groups of gate valves together to reduce personnel requirements or control the flow of oil and gas from a group of oil and gas producing wells. It is imperative that such gate valve actuators operate dependably and allow certain operational features.  
           [0004]    The gate valves that these gate valve actuators are operating generally consist of a valve with a through bore concentric with inlet and outlet passages. The flow of fluid such as oil or gas through the valve is controlled by a slab of material or gate as it is commonly referred to in the industry. This gate is slidable vertically by the aforementioned actuator. In the open position, a bore in the gate aligns with the inlet and outlet passages to allow oil and gas to flow through the valve. Such gates are typically referred to as reverse acting gates, i.e., when the actuator moves the gate, typically upward, away from the valve bore to the closed position, the bore in the gate moves out of alignment with the inlet and outlet passages and flow is stopped. The actuator is biased to move the gate to the closed position and the valve is referred to as a reverse acting gate valve or fail closed gate valve. A valve designed to fail open is accomplished with a gate having the bore moved inwardly or more closely to the end of the gate, referred to as a direct acting gate valve. Seal rings, usually positioned in the inlet and outlet passages adjacent the gate, ensure effective sealing and no leakage through the valve.  
           [0005]    These valve actuators use pneumatic or hydraulic operating pressure to move the gate to its open position. This operating pressure typically operates a diaphragm or piston to supply the force needed to hold the gate in the open position. A powerful spring is positioned in the actuator housing and is compressed by the movement of the diaphragm or piston. The energy or force stored in the compressed spring will force the gate to its closed position when operating pressure is removed from the diaphragm or piston. This ensures the valve will fail safe closed in the event operating pressure is lost. These springs typically are compressed initially during assembly of the valve actuator. It would be desirable to have a mechanism incorporated in the design of the actuator that would allow easy compression of this spring without requiring specialized spring compression assembly tools.  
           [0006]    It is desirable to be able to remove the actuator from the gate valve, even when the gate valve is in the closed position and containing pressure, for maintenance or repair. Additionally, the operating pressure to operate the actuator is often supplied through hard or rigid piping. This arrangement requires the actuator to be oriented to a certain position to allow connection. It is therefore desirable for the actuator to be able to rotate to any position to allow connection to the hard piping.  
           [0007]    2. Description of Related Art  
           [0008]    U.S. Pat. No. 3,958,592 to R. E. Wells et al. shows a pneumatic gate valve actuator with control chamber seals designed to disintegrate in a fire and allow spring pressure to close the valve.  
           [0009]    A pneumatic gate valve actuator utilizing a toroidal or tire casing shaped pressure chamber is disclosed in U.S. Pat. No. 4,783,046 to T. G. Young et al.  
           [0010]    U.S. Pat. No. 4,967,785 to T. G. Young shows a gate valve actuator having a variable volume.  
           [0011]    A hydraulic gate valve actuator or booster module for use in cutting wireline in a valve bore during closing is disclosed in U.S. Pat. No. 5,178,360 to T. G. Young.  
           [0012]    U.S. Pat. No. 6,089,531 to T. G. Young shows pneumatic and hydraulic gate valve actuators that allow removal of the valve actuators without disturbing the bonnet stem drift adjustment.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention comprises a gate valve actuator that utilizes a universal mounting ring interposed between the valve bonnet and actuator housing to allow the mounting of different sizes and types of gate valve actuators onto a given gate valve. A first embodiment of the present invention uses a pneumatically operated diaphragm. The valve actuator comprises an actuator housing connected to a valve bonnet through a universal mounting ring for coupling the actuator to a valve. The valve bonnet includes a valve stem bore extending there through and a seal assembly disposed around the periphery of the valve stem bore for sealing a valve stem extending through the valve bonnet.  
           [0014]    The actuator housing includes upper and lower sections that are sealing bolted together. The upper section of the actuator housing includes a cap nut welded into the upper section and an indicator stem extending therethrough. The lower end of the indicator stem is sealingly secured to a diaphragm support plate by a retainer nut. The flexible rubber diaphragm extends radially outwardly where it is secured between the upper and lower sections of the actuator housing. A fluid port allows introduction of pressurized fluid into the pressure chamber thus formed.  
           [0015]    The diaphragm support plate can move downward and contact the power screw which is threaded into the stem adapter that is threaded onto the upper end of the valve stem. A large coil spring is positioned around the stem adapter and valve stem. The upper end of the coil spring bears against a spring retainer plate that is retained on the stem adapter by a flange on the exterior of the power screw. When the power screw is threaded into the stem adapter, the spring retainer plate compresses the spring. The lower end of the spring sits on a shoulder in the valve bonnet.  
           [0016]    An annular seal is positioned in the valve bonnet bore and retained therein by a seal retainer nut. The exterior of the valve bonnet adjacent the actuator housing has an external thread formed thereon. A mounting ring having an internal thread is threaded onto the external thread of the valve bonnet. The actuator housing lower section has a counterbore formed therein and the counterbore is sized to closely engage the exterior of the mounting ring. A retainer groove is machined in the counterbore of the actuator housing lower section and an outwardly biased retainer ring is positioned in the retainer groove to secure the actuator housing to the mounting ring.  
           [0017]    A secondary backup is provided in the form of a solid backup ring positioned adjacent the retainer ring when the retainer ring is outwardly biased to prevent inward movement of the retainer ring. The solid backup ring is secured to the mounting ring by retainer bolts. A plurality of set screws is radially positioned in the mounting ring and engages the valve bonnet to prevent rotation of the mounting ring relative to the valve bonnet. Additionally, a plurality of set screws is radially positioned in the actuator housing and engages the mounting ring to prevent rotation of the actuator housing relative to the mounting ring. When it is desired to rotate the actuator housing relative to the valve bonnet, to aid in alignment of the valve actuator housing with adjacent piping, the aforementioned set screws can be loosened and the actuator housing rotated to the desired position.  
           [0018]    Additional embodiments are shown. A second embodiment utilizes a second spring positioned around the first spring to provide a greater closing force. A third embodiment utilizes an annular piston in place of the diaphragm to provide the pneumatic force required to open the valve. A final embodiment utilizes a hydraulically actuated valve actuator that provides the same rotation and anti-tampering characteristics as the pneumatic actuators.  
           [0019]    A principal object of the present invention is to provide a valve actuator for use with gate valves with a fully rotatable connection between the actuator and valve bonnet without the need for bolts that are susceptible to corrosion.  
           [0020]    Another object of the present invention is to provide a valve actuator with a rotatable connection between the valve actuator and valve to allow orienting the valve actuator&#39;s pressure supply port in any desired direction without actuator disassembly.  
           [0021]    A final object of the present invention is to provide a valve actuator with a power screw incorporated into its design to allow compression of the actuator urging means or spring without requiring specialized valve actuator assembly tools.  
           [0022]    These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:  
         [0024]    [0024]FIG. 1 is an elevation view, partially in section, of a pneumatically actuated diaphragm type valve actuator embodying the present invention.  
         [0025]    [0025]FIG. 2 is an elevation view, partially exploded, showing the power screw of the present invention.  
         [0026]    [0026]FIG. 3 is an elevation view, partially in section, of a pneumatically actuated diaphragm type valve actuator with an additional power spring embodying the present invention.  
         [0027]    [0027]FIG. 4 is an elevation view, partially in section, of a pneumatically actuated piston type valve actuator embodying the present invention.  
         [0028]    [0028]FIGS. 5A and 5B are an elevation view, partially in section, of a hydraulically actuated piston type valve actuator embodying the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    With reference to the drawings, and particularly to FIG. 1, an elevation view, partly in section, of a valve actuator  10  embodying the principles of the present invention is shown. Valve actuator  10  comprises actuator housing  12  secured to valve bonnet  14 . Valve bonnet  14  is secured to gate valve  16  (shown in partial section) by suitable securing means as studs  18  and nuts  20 . Gate valve  16  is of a conventional configuration well known to those of ordinary skill in the art with valve gate  22  movable therein between open and closed positions by valve actuator  10 . Valve gate  22  is typically a reverse acting gate, i.e., when the actuator moves the gate, typically upward, away from the valve bore to the closed position, the bore in the gate moves out of alignment with the inlet and outlet passages and flow is stopped. Such a valve is referred to as a reverse acting gate valve or fail closed gate valve. A valve designed to fail open is accomplished with a gate having the bore moved inwardly or more closely to the end of the gate, referred to as a direct acting gate valve. Either configuration may be used with the actuator of the present invention without departing from the scope of the invention.  
         [0030]    Actuator housing  12  is a generally cylindrical member composed of upper section  24  and lower section  26 . Upper section  24  and lower section  26  have integrally formed flanges on their periphery and are secured together by suitable securing means as bolts  28  and nuts  30 . Upper section  24  is a domed structure with cap nut  32  welded into the top. Cap nut  32  is counterbored to receive sealing means in the form of seal assembly  34  that is inserted in cap nut  32  and retained by snap ring  36 . Seal assembly  34  seals against indicator stem  38  which extends through cap nut  32 . The lower end of indicator stem  38  has a flange  40  formed thereon. Retainer nut  42  in threaded into diaphragm support plate  44  and prevents indicator stem  38  from pulling through diaphragm support plate  44 . O rings  43  positioned on the interior of retainer nut  42  seal against indicator stem  38 .  
         [0031]    Diaphragm support plate  44  has flexible diaphragm  46  attached to its upper face by retainer nut  42 . Diaphragm  46  seals against diaphragm support plate  44 . The inner edge of flexible diaphragm  46  has metal ring  47  molded therein which in turn seals against O ring  43  when retainer nut  42  is tightened. The outer edge of flexible diaphragm  46  is sealingly secured between upper section  24  and lower section  26  by bolts  28  and nuts  30 . The combination of flexible diaphragm  46  sealed between upper section  24  and lower section  26 , sealed to support plate  44  and the sealing of cap nut  32  to indicator stem  38  forms pressure chamber  50 . Flexible diaphragm  46  and diaphragm support plate  44  form a pressure responsive member that is moveable toward gate valve  16  in response to pressurized fluid, i.e., compressed air introduced into pressure chamber  50  through fluid port  48  welded into the wall of upper section  24 .  
         [0032]    Actuator housing lower section  26  includes an exhaust port  52  machined in its lower portion allowing air to be exhausted from actuator housing  12  when pressure chamber  50  is pressurized and flexible diaphragm  46  and diaphragm support plate  44  move toward gate valve  16 . The end of actuator housing lower section  26  has a counterbore  54  machined therein. Formed in counterbore  54  is retainer groove  56  with outwardly biased retainer ring  58  therein. Retainer ring  58  is a generally “C” shaped ring of square cross-section. Retainer ring  58  is machined to fit tightly within retainer groove  56  in its relaxed condition. Adjacent counterbore  54  of actuator housing lower section  26  is mounting ring  60 .  
         [0033]    Mounting ring  60  has internal thread  62  formed on its interior and its exterior is machined to fit closely within counterbore  54  of actuator housing lower section  26 . As seen in FIG. 1, when mounting ring  60  engages counterbore  54  and retainer ring  58  is in place, the overlap of retainer ring  58  with the edge of mounting ring  60  locks actuator housing  12  to mounting ring  60 . At the same time, this configuration allows the rotation of actuator housing  12  to any desired position to allow connection of piping (not shown) to fluid port  48 . Although retainer ring  58  is in its relaxed position in retainer groove  56  as noted above, a backup system is provided to ensure actuator housing  12  cannot be uncoupled from mounting ring  60  unintentionally. This includes solid support ring  64  of “L” shaped cross-section that is secured to mounting ring  60  by suitable securing means as retainer bolts  66 . Support ring  64  ensures retainer ring  58  cannot be contracted inwardly and thereby release actuator housing  12  from mounting ring  60  unintentionally. A plurality of set screws  68  are threaded through actuator housing lower section  26  to contact mounting ring  60  and prevent relative movement between actuator housing  12  and mounting ring  60 .  
         [0034]    Adjacent mounting ring  60  and radially inward is valve bonnet  14 . Valve bonnet  14  has exterior thread  70  on its upper end that is engaged by internal thread  62  of mounting ring  60  to secure mounting ring  60  and hence actuator housing  12  to valve bonnet  14 . Valve bonnet  14  is secured by gate valve  16  as previously noted. The use of exterior thread  70  on valve bonnet  14  in combination with mounting ring  60  allows an operator to use different size and types of actuators on a given valve by simply using a mounting ring sized to fit between valve bonnet  14  and a given valve actuator. This allows an operator to use a larger actuator when pressure loads so dictate. A plurality of set screws  72  are threaded through mounting ring  60  to contact valve bonnet  14  and prevent relative movement between valve bonnet  14  and mounting ring  60 .  
         [0035]    Valve bonnet  14  has bore  74  extending therethrough with counterbore  76  at its upper end. Seal ring  78  is positioned in counterbore  76  to seal against actuator stem  80  extending therethrough. Seal  78  is secured within counterbore  76  by seal retaining nut  82  threaded into valve bonnet  14 . Actuator stem  80  includes enlarged diameter  84  that engages shoulder  86  of valve bonnet  14  to limit axial movement of actuator stem  80  with respect to valve  14  and hence gate valve  16 . Shims  88  in the form of annular rings are positioned on seal retaining nut  82  to set the downward movement limit of actuator  12  and ensure the bore in valve gate  22  aligns with the inlet and outlet passages in gate valve  16  in a manner well known to those of ordinary skill in the art. A recess  90  is formed in the upper end of valve bonnet to locate and centralize urging means or actuator spring  92 .  
         [0036]    Secured to the outer end of actuator stem  80  is stem adapter  94 . Stem adapter  94  is sized to shoulder against actuator stem  80  and form a rigid connection therebetween. Stem adapter  94  is locked against rotation with respect to actuator stem  80  by set screws  96 . Stem adapter  94  is counterbored with thread  98  machined therein. The upper exterior of stem adapter  94  has step  100  machined thereon upon which urging means or spring retainer  102  rests. Engaging thread  98  of stem adapter  94  is power screw  104 . Power screw  104  has a hex  106  formed on its upper end for engagement by a wrench to allow threading power screw  104  into stem adapter  94 . Power screw  104  also has flange  108  on its upper end to engage spring retainer  102 . As best seen in FIG. 2, when power screw  104  initially engages thread  98  of stem adapter  94 , spring  92  is uncompressed. As power screw  104  is threaded into stem adapter  94 , flange  108  of power screw  104  acts on spring retainer  102  to compress spring  92 , thereby avoiding the need for special tools during assembly and allowing quick and easy assembly and disassembly of the actuator.  
         [0037]    The sequence of operation for the gate valve  16  and valve actuator  10  is as follows. In the position shown in FIG. 1, pressure chamber  50  is at ambient pressure and spring  92  has pushed upwardly on spring retainer  102  to move valve gate  22  to its upper or closed position. When it is desired to open gate valve  16 , pressurized fluid is supplied to pressure chamber  50 . This pressure acts on diaphragm  46  to force diaphragm support plate  44  into contact with power screw  104  and thereby compress spring  92 . This forces stem adapter  94  and actuator stem  80  to move downwardly thereby opening gate valve  16 . As long as pressure is maintained in pressure chamber  50 , gate valve  16  will remain open. In this pressurized condition, the pressure applied in pressure chamber  50  acts to try and pull actuator housing  12  away from mounting ring  60 . As noted previously, this load is resisted by retainer ring  58 . When retainer ring  58  is thus loaded, this large force creates sufficient friction between retainer ring  58 , retainer groove  56  and mounting ring  60  to ensure that it is virtually impossible for retainer ring  58  to be retracted and thereby ensure actuator housing  12  is locked to mounting ring  60 . When pressure is released from pressure chamber  50 , spring  92  moves valve gate  22  to its closed position and the aforementioned large load on retainer ring  58  is relieved and retainer ring  58  may be retracted should it be desired to remove actuator housing  12  from mounting ring  60 .  
         [0038]    A second embodiment of the present invention is shown in FIG. 3 that allows additional springs to be added to provide additional closing force and facilitate wireline cutting features. Those items which are the same as in the first embodiment retain their numerical designation. Valve actuator  200  comprises actuator housing  202  secured to valve bonnet  14 . Actuator housing  202  is the same as in the first embodiment except for being a larger diameter to accommodate booster spring  204  positioned radially outwardly from spring  92 . Spring retainer  206  is of the same configuration as in the first embodiment but of a larger diameter to accommodate booster spring  204 . The lower end of booster spring  204  rests on mounting ring  208 , also sized to allow for the fitting of booster spring  204  and actuator housing  202 . In all other respects, valve actuator  200  functions the same as the first embodiment and offers the same unique functional advantages.  
         [0039]    A third embodiment of the present invention is shown in FIG. 4 that uses a pressure responsive piston in place of the flexible diaphragm to provide the opening force. Those items which are the same as in the first embodiment retain their numerical designation. Valve actuator  300  comprises actuator housing  302  secured to valve bonnet  14  in the same manner as in the previous embodiments.  
         [0040]    Actuator housing  302  is a generally cylindrical member of stepped configuration with upper section  304  and lower section  306 . Upper section  304  is sized to accommodate actuator piston  308 . Actuator housing  302  has an open upper end with removable top cap  310  sealingly secured to upper section  304  by split retainer ring  312 . Sealing means as O ring  314  is positioned on outside of top cap  310  to seal against upper section  304 . Cap nut  32  is integrally formed on top cap  310  and receives seal assembly  34  therein as in the first embodiment. Seal assembly  34  seals against and wear ring  316  guides indicator stem  38  which extends through cap nut  32 . Indicator stem  38  is secured to actuator piston  308  by retainer nut  42 . Actuator piston  308  has suitable sealing means as O ring  318  positioned on its exterior to seal against interior wall  320  of upper section  304 . The combination of actuator piston  308  sealed between upper section  304  and retainer nut  42  and the sealing of retainer nut  42  and top cap  310  to indicator stem  38  forms pressure chamber  322 . Actuator piston  308  forms a pressure responsive member that is moveable toward gate valve  16  in response to pressurized fluid, i.e., compressed air introduced into pressure chamber  322  through fluid port  324  machined in top cap  310 .  
         [0041]    In all other respects, valve actuator  300  functions as in the first embodiment. Actuator housing  302  is secured by retainer ring  58  to mounting ring  60  and hence to valve bonnet  14 . Actuator stem  80  extends through valve bonnet  14  where stem adapter  94  is attached. Spring  92  is retained by spring retainer  102  which is held against stem adapter  94  by power screw  104 .  
         [0042]    A fourth embodiment of the present invention is shown in FIG. 5 that uses a hydraulically actuated valve actuator in place of the pneumatically actuated valve actuators of the previous embodiments. Those items which are the same as in the first embodiment retain their numerical designation. Valve actuator  400  comprises actuator housing  402  secured to valve bonnet  14  in the same manner as in the previous embodiments.  
         [0043]    Actuator housing  402  is a generally cylindrical member of consisting of upper section  404  and lower section  406 . Upper section  404  is sized to accommodate actuator piston  408 . Upper section  404  and lower section  406  are secured in abutting relationship by threaded joint  410 . A plurality of set screws  412  are threaded through lower section  406  to engage upper section  404  and ensure threaded joint  410  does not come loose.  
         [0044]    Upper section  404  has a radially inwardly turned flange to form end cap  414 . Cap nut  416  is integrally formed on end cap  414  and has suitable sealing means as “T” seals  418  positioned on its interior to seal against indicator stem  420  which extends through cap nut  416 . Indicator stem  420  is secured to actuator piston  408  by retainer ring  422  and screws  424 . Actuator piston  408  has suitable sealing means as “T” seals  426  positioned on its exterior to seal against interior wall  428  of upper section  404 . The combination of actuator piston  408  sealed against upper section  404  and the sealing of retainer nut  416  to indicator stem  420  forms pressure chamber  430 . Actuator piston  408  forms a pressure responsive member that is moveable toward gate valve  16  in response to pressurized fluid, i.e., pressurized hydraulic fluid introduced into pressure chamber  430  through fluid port  432  machined in upper section  404 .  
         [0045]    Actuator housing  402  is secured by retainer ring  434  to mounting ring  436  as in the previous embodiments and hence to valve bonnet  14 . Actuator stem  80  extends through valve bonnet  14  where stem adapter  438  is attached. Stem adapter  438  is sized to shoulder against actuator stem  80  and form a rigid connection therebetween. Stem adapter  438  is locked against rotation with respect to actuator stem  80  by set screws  440 . Stem adapter  438  has external thread  442  machined therein. The upper exterior of stem adapter  438  has step  444  machined thereon upon which urging means or spring retainer  446  rests. Stem adapter  438  has hex  448  machined on its upper end for engagement by a socket to hold stem adapter  438  to allow threading spring retainer  446  onto external thread  442  of stem adapter  438 . Spring retainer  446  has flange  450  formed on its upper end that acts as upper retainer for spring  452 . The engagement of spring retainer  446  with thread  442  of stem adapter  438  acts as the power screw of the previous embodiments to allow compression of spring  452  without the use of special tools.  
         [0046]    In all other respects valve actuator  400  operates as in the previous embodiments. Introduction of pressurized hydraulic fluid into pressure chamber  430  causes piston  408  to contact spring retainer  446  and thereby compress spring  452 . This forces stem adapter  438  and actuator stem  80  to move downwardly thereby opening gate valve  16 . As long as pressure is maintained in pressure chamber  430 , gate valve  16  will remain open. When pressure is released from pressure chamber  430 , spring  452  moves valve gate  22  to its closed position.  
         [0047]    The construction of our valve actuator will be readily understood from the foregoing description and it will be seen that we have provided a valve actuator with a fully rotatable connection between the actuator and valve bonnet without the need for bolts that are susceptible to corrosion that allows orienting the valve actuator&#39;s pressure supply port in any desired direction without actuator disassembly. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims.