Patent Publication Number: US-2013240052-A1

Title: Gate valve assemblies and methods of use

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/533,094, entitled “PIVOTING GATE VALVE,” filed Sep. 9, 2011, the content of which is incorporated herein, in its entirety, by this reference. 
    
    
     BACKGROUND 
     Valves are commonly used in industry for isolating process media, fluids, and/or gases. Valves may also be used in industry for controlling the flow of low or high pressure process media, fluids, and/or gases in a process system. In many applications, such valves are subject to severe operating conditions such as high temperatures, high pressures, abrasives, corrosives, toxic materials, residual build-up, debris, and/or vibration. Consequently, there may be severe energy drops or pressure losses across the valve or excessive build-up in the valve, which may cause vibration, cavitation, and/or blockage, each of which may damage the valve and/or cause excessive noise in the process system. Further, as the valve is damaged, the flow characteristics of the valve may be abruptly altered or gradually altered over time. The altered flow characteristics may be unpredictable, dangerous, and/or erratic, thus greatly complicating operation of the process system and/or maintenance of the valve. Moreover, in some cases, altered flow characteristics and/or valve damage may ultimately cause failure of the valve, thereby jeopardizing human safety and/or the integrity of the process system. 
     Therefore, manufacturers and users of valves continue to seek improved valve designs and methods of use. 
     SUMMARY 
     Embodiments of the invention relate generally to gate valve assemblies and methods of use. In an embodiment, a valve assembly may include a housing having an orifice defining a flow path through the housing and a valve closure element positioned within the housing configured to control fluid flow through the housing. The valve closure element may include a side surface and drive teeth extending along at least a portion of the side surface. The valve closure element may be selectively rotatable about a rotation axis between an open position, wherein fluid flows through the orifice, and a closed position, wherein fluid flow is substantially obstructed by the valve closure element. The valve assembly may also include a worm gear assembly positioned and configured to selectively engage or mesh with one or more of the drive teeth such that rotation of the worm gear assembly may rotate the valve closure element between the closed position and the open position. 
     In an embodiment, a valve assembly may include a valve body having a flow orifice extending therethrough. Valve assembly may also include a first valve bonnet removably coupled to a first end of the valve body and a second valve bonnet removably coupled to a second end of the valve body. In addition, valve assembly may include a valve chamber at least partially defined by the valve body and the valve bonnets. An elliptical or kidney-like shaped gate may be positioned within the chamber and configured to control fluid flow through the flow orifice. The gate may include a gate orifice extending therethrough, a side surface, and a plurality of gate drive teeth extending along at least a portion of the side surface of the gate. The gate may be selectively rotatable about a rotation axis between an open position, wherein the flow orifice and the gate orifice are at least partially aligned, and a closed position, wherein a solid portion of the gate obstructs the flow orifice. The valve assembly may further include a worm gear assembly positioned and configured to selectively engage or mesh with one or more of the drive teeth. Rotation of the worm gear assembly may rotate gate about the rotation axis to move the gate between the closed position and the open position. Finally, valve assembly may include a seat assembly positioned within the chamber and configured to form and/or maintain a seal between the gate and seat assembly. 
     In an embodiment, a method of controlling fluid flow through a gate valve may include connecting a gate valve to a vessel, coupling, or a pipeline. The gate valve may include a housing having an orifice defining a flow path through the gate valve. A gate may be positioned within the housing and configured to control process media flow through the gate valve. The gate may include a side surface and a plurality of gate drive teeth extending along at least a portion of the side surface. The gate may be selectively rotatable about a rotation axis between an open position, wherein process media flows through the gate valve, and a closed position, wherein process media flow through the gate valve is substantially obstructed by the gate. The gate valve may further include a worm gear assembly positioned and configured to selectively engage one or more of the gate drive teeth. Rotation of the worm gear assembly may rotate the gate about the rotation axis to move the gate between the closed and open positions. An actuator may be operably connected to the worm gear assembly. The actuator may be configured to control rotation of the worm gear assembly to move the gate between the open and closed position. The method may further include controlling process media flow through the gate valve by controlling the worm gear assembly with the actuator. 
     Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate several embodiments of the invention, wherein identical reference numerals refer to identical elements or features in different views or embodiments shown in the drawings. 
         FIG. 1A  is a perspective view of a valve assembly according to an embodiment. 
         FIG. 1B  is cross-sectional view of the valve assembly shown in  FIG. 1A  taken along section line  1 B- 1 B. 
         FIG. 1C  is a perspective view of the valve assembly shown in  FIG. 1A  in a closed position according to an embodiment; 
         FIG. 1D  is a perspective view of the valve assembly shown in  FIG. 1A  in an open position according to an embodiment; 
         FIG. 2  is a perspective view of a gate according to an embodiment; 
         FIG. 3  is a perspective view of a gate according to another embodiment; 
         FIG. 4  is a perspective view of a gate according to another embodiment; 
         FIG. 5  is a partial perspective view of a valve assembly that illustrates a gate drive system according to an embodiment; 
         FIG. 6  is a perspective view of a valve body according to an embodiment; 
         FIG. 7  is a perspective view of a connection between valve body and a valve bonnet according to an embodiment; 
         FIG. 8  is a partial perspective view of a valve assembly that illustrates an indicator according to an embodiment; 
         FIG. 9  is a perspective view of a valve bonnet according to an embodiment; 
         FIG. 10A  is a perspective view of a seat assembly according to an embodiment; 
         FIG. 10B  is a cross-sectional view of seats according to an embodiment; 
         FIG. 10C  is a cross-sectional view of seats according to another embodiment; 
         FIG. 10D  is a cross-sectional view of seats according to another embodiment; 
         FIG. 10E  is a cross-sectional view of seats according to another embodiment; 
         FIG. 10F  is a cross-sectional view of seats according to another embodiment; 
         FIG. 10G  is a cross-sectional view of seats according to another embodiment; 
         FIG. 10H  is a cross-sectional view of seats according to another embodiment; and 
         FIG. 11  is a partial perspective view of a valve assembly that illustrates support members according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention relate generally to gate valve assemblies and methods of use for isolation and control applications. More specifically, embodiments of the invention relate to gate valve assemblies configured to be tight sealing, low maintenance, durable, and more efficient to operate. 
       FIGS. 1A and 1B  are perspective and cross-sectional views, respectively, of an embodiment of a valve assembly  100 . The valve assembly  100  may include a housing  102  and a valve closure element or gate  104 . In an embodiment, housing  102  may comprise a valve body  106  and valve bonnets  108  removably coupled to opposing ends of valve body  106 . As shown, valve body  106  may include a generally cylindrical orifice  110  that defines a flow path through valve body  106 . A valve chamber  112  may be at least partially defined within valve body  106  and valve bonnets  108 . Valve chamber  112  may generally traverse the flow path through orifice  110  and may be configured to house at least gate  104  and a seat assembly  114  configured to form and/or maintain a seal between at least gate  104 , valve body  106 , and seat assembly  114 . In an embodiment, gate  104  may be connected to a pivot point shaft  136 . As described in more detail below, gate  104  may be selectively rotatable about a rotation axis  117  to move or slide gate  104  between an open position, wherein fluid may flow through orifice  110  (shown in  FIGS. 1A and 1C ), and a closed position, wherein fluid flow through orifice  110  is substantially obstructed by gate  104  (shown in  FIG. 1D ). Gate  104  may slide or move from the open to closed position and back, between two sealing surfaces or seats  182 ,  184  (shown in  FIG. 10 ) of the seat assembly  114 . Gate  104  may include a plurality of gate drive teeth  160  (shown in  FIG. 2 ) extending along at least a portion of a side surface  158  (shown in  FIG. 2 ) of gate  104 . In an embodiment, valve assembly  100  may include a gate drive system  116  configured to engage one or more drive teeth of gate  104  to move or slide gate  104  between the open and closed positions. Valve assembly  100  may further include one or more support members  118  integral to or removably attached to valve bonnets  108  and/or valve body  106 . Optionally, valve assembly  100  may further include a position indicator  132  configured to indicate whether gate  104  is in the open position, the closed position, or in some position in between. 
     Valve assembly  100  or any component thereof may be configured to be compliant with applicable valve design standards and/or codes for applications and/or services within which valve assembly  100  may operate. For example, one or more components of valve assembly  100  may be configured to operate under severe service conditions. In an embodiment, one or more components of valve assembly  100  may be configured to operate in temperatures between about negative one hundred and fifty (−150)° F. and about two thousand (2000)° F., about negative one hundred (−100)° F. and about fifteen hundred (1500)° F., or about negative fifty (−50)° F. and about twelve hundred (1200)° F. In other embodiments, one or more components of valve assembly  100  may be configured to operate in higher or lower temperatures. 
     In an embodiment, one or more components of valve assembly  100  may be configured to operate under pressures between vacuum and about forty-five hundred (4500) psi; between vacuum and about four thousand (4000) psi, about vacuum and about thirty-five hundred (3500) psi; about 0 psi and about three thousand (3000) psi, or about 0 psi and about twenty-five hundred (2500) psi. In other embodiments, one or more components of valve assembly  100  may be configured to operate under higher or lower pressures. 
     In yet other embodiments, one or more components of valve assembly  100  may be configured to handle abrasives, corrosives, solids, toxic materials, and/or other chemicals. Valve assembly  100  may include one or more high strength and/or chemical resistant materials. For example, one or more components of valve assembly  100  may include steel, galvanized steel, stainless steel, iron, ductile iron, carbon steel, gun metal, alloy steel, alloy steels, one or more metal alloys, one or more polymeric materials, rubber, ceramics, composite materials, brass, combinations thereof, or any other suitable material. 
     Valve assembly  100  may also be sized and configured for various different applications and/or services. For example, in an embodiment, valve assembly  100  may exhibit a height H between about a half (0.5) foot and about twenty (20) feet; between about one (1) foot and about twelve and a half (12.5) feet; or about three (3) feet and about ten (10) feet. In an embodiment, valve assembly  100  may exhibit a height H of about one (1) foot; of about five (5) feet; of about ten (10) feet; of about twelve and a half (12.5) feet; or about fifteen (15) feet. In other embodiments, valve assembly  100  may exhibit larger or smaller heights. 
     In an embodiment, valve assembly  100  may exhibit a width W between about a half (0.5) foot and about thirty (30) feet; between about one (1) foot and about twenty (20) feet; between about three (3) feet and about twelve and a half (12.5) feet; or about three (3) feet and about ten (10) feet. In other embodiments, valve assembly  100  may exhibit larger or smaller widths. 
     While housing  102  is illustrated having a generally truncated heart-like shape, in other embodiments housing  102  may have a generally rounded rectangular shape, a generally kidney shape, a generally elliptical shape, a symmetrical shape, an asymmetrical shape, combinations thereof, or any other suitable shape. Moreover, while housing  102  is illustrated as comprising valve body and separate valve bonnets, in other embodiments, housing  102  may comprise a valve body, a valve body and a single valve bonnet, or any other suitable number of members. Further, while valve bonnets  108  are illustrated as being generally identical or similar, in other embodiments, valve bonnets  108  may be different. For example, in an embodiment, one of the valve bonnets  108  may have a different size and/or shape than the other valve bonnet  108 . In addition, while orifice  110  is illustrated being generally cylindrical, in other embodiments, orifice  110  may be generally rectangular, generally elliptical, generally oval, or any other suitable shape. 
       FIG. 2  illustrates gate  104  according to an embodiment. As noted above, gate  104  may be moveably positioned within valve chamber  112  and may be configured to selectively rotate about a rotation axis  117  to move or slide gate  104  between an open position, wherein process fluid and/or other materials may flow through orifice  110  (shown in  FIG. 1A ), and a closed position, wherein fluid flow through orifice  110  is substantially obstructed by gate  104 . In an embodiment, gate  104  may be sized and configured to efficiently move through valve chamber  112 . In an embodiment, gate  104  may exhibit a kidney-like shape that allows gate  104  to move between the open and closed positions while being supported within valve assembly  100  and occupying a limited amount of space within valve chamber  112  (shown in  FIGS. 1C and 1D ). For example, in an embodiment, gate  104  may be substantially removed from one of the bonnets  108  or substantially positioned in only valve body  106  and one of bonnets  108  in the closed position. Such a configuration may help reduce the overall weight of valve assembly  100 . In an embodiment, gate  104  may move between the open and closed positions along an arcuate path such that the linear distance traveled by gate  104  is reduced. Moreover, the geometric shape of one or more portions of gate  104  may generally correspond to the geometric shape of valve chamber  112  to help gate  104  efficiently and/or smoothly move in and out of bonnets  108  as gate  104  moves between the open and closed positions. 
     While gate  104  is illustrated exhibiting a generally kidney-like shape, in other embodiments, gate  104  may exhibit a generally teardrop-like shape, a generally rounded rectangular shape, a generally elliptical shape, an asymmetrical shape, combinations thereof, or any other suitable shape. 
     In addition, gate  104  may include a pivot point shaft receiver  144  formed therein. As described in more detail below, pivot point shaft receiver  144  may be configured to receive pivot point shaft  136  (shown in  FIG. 1B ) connected to gate  104 . Pivot point shaft  136  may define rotation axis  117  for gate  104 . In an embodiment, when gate  104  and pivot point shaft  136  rotate about rotation axis  117 , gate  104  may move between the open and closed positions. In other embodiments, pivot point shaft  136  may be fixedly attached to valve body  106  and gate  104  may be pivotally connected to pivot point shaft  136  such that gate  104  rotates about pivot point shaft  136 . 
     In an embodiment, pivot point shaft receiver  144  may be offset from a geometric center of gate  104  such that rotation of gate  104  about the rotation axis defined by pivot point shaft  136  is asymmetrical. In other embodiments, pivot point shaft receiver  144  may be generally aligned with a geometric center of gate  104  such that rotation of gate  104  about the rotation axis is symmetrical. Gate  104  may further include a gate orifice  156  through which process media and/or other materials may flow when gate  104  is in an open position. For example, in an embodiment, gate orifice  156  may be at least partially aligned with orifice  110  in the open position. In other embodiments, gate orifice  156  may be substantially aligned with orifice  110  in the open position. In the closed position, gate orifice  156  may move inside of one of bonnets  108  and/or valve body  106  and a solid portion of gate  104  may obstruct flow through orifice  110 . Accordingly, gate  104  may open and close valve assembly  100  without the entirety of gate  104  having to pass over the seats  182 ,  184  of seating assembly  114  and/or orifice  110 . Such a configuration may reduce the overall size, weight, and/or cost of valve assembly  100 . Gate orifice  156  may exhibit a circular cross-sectional shape and may include an inner diameter that is similar to an outer diameter of a process pipeline, coupling, or vessel to which valve assembly  100  is attached. In other embodiments, gate orifice  156  may exhibit other cross-sectional shapes. For example, in other embodiments, gate orifice  156  may exhibit a generally parabolic cross-sectional shape, a generally rectangular cross-sectional shape, a generally v-notch cross-sectional shape, or any other suitable cross-sectional shape. 
     Gate  104  may include seating surfaces  154  opposite one another and a side surface  158  extending between the seating surfaces  154 . Seating surfaces  154  of gate  104  may be configured to contact seats  182 ,  184  of the seating assembly  114  to form a seal between the gate  104  and seating assembly  114 . In an embodiment, seating surfaces  154  of gate  104  may be generally planar and generally parallel to one another. In other embodiments, one or more of seating surfaces  154  of gate  104  may be generally tapered or inclined such that gate  104  forms a wedge-like shape. Such a configuration may allow for sealing and/or seating forces to increase as more of gate  104  is rotated over seats  182 ,  184  of the seat assembly  114 . 
     Gate  104  may include a plurality of gate drive teeth  160  extending along at least a portion of side surface  158  of gate  104 . For example, gate drive teeth  160  may extend along a portion of side surface  158  near worm drive assembly  170  (shown in  FIG. 5 ). In another embodiment, gate drive teeth  160  may extend along the entirety of the side surface  158  (e.g., the entire periphery of gate  104 ). In other embodiment, gate drive teeth  160  may extend along intermittent portions of side surface  158 . 
     In an embodiment, gate drive teeth  160  may be configured to engage or mesh with worm gear assembly  170  (shown in  FIG. 5 ) such that rotation of worm gear assembly  170  rotates gate  104  about rotation axis  117  to move gate  104  between the open and closed positions. In an embodiment, one or more of gate drive teeth  160  may be integral to side surface  158  of gate  104 . In other embodiments, one or more of gate drive teeth  160  may be removably connected to side surface  158  of gate  104 . For example, gate  104  may have teeth receiving slots  162  (shown in  FIG. 3 ) formed in side surface  158 . Teeth receiving slots  162  and/or gate drive teeth  160  may be formed in any suitable manner such as via machining, cutting, laser cutting, molding, or any other suitable technique. For example, in an embodiment, gate drive teeth  160  may be cast, forged, or cut from solid plate steel, or other suitable materials. Each of teeth receiving slots  162  may be configured to receive individual gate drive teeth  160 . In other embodiments, teeth receiving slots  162  may be configured to receive sets of gate drive teeth  160 . For example, gate drive teeth  160  may be formed in sets or groups of two, three, four, five, or any other suitable number of gate drive teeth  160  which may then be inserted into and/or removed from teeth receiving slots  162  as a group or set. Such a configuration may allow gate drive teeth  160  to be easily replaced as needed. Thus, gate drive teeth  160  may be quickly and efficiently repaired without the need of replacing gate  104 . For example, gate drive teeth  160  may be sized such that individually, in sets, or in groups, gate drive teeth  160  are relatively small and are easy to be changed by hand and/or with basic tools. 
     In an embodiment, gate drive teeth  160  may be customizable for different applications. For example, in a process application where extremely high temperatures (e.g., 1200° F.) may be experienced by valve assembly  100 , gate drive teeth  160  exhibiting high melting points or low thermal expansion properties may be inserted in teeth receiving slots  162 . By way of another example, in a process application where valve assembly  100  may be under high pressures (e.g., 2500 psi), gate drive teeth  160  exhibiting higher yield strengths may be inserted in teeth receiving slots  162 . Moreover, gate drive teeth  160  may be sized and configured to minimize friction and wear. For example, in an embodiment, gate drive teeth  160  may be coated with one or more hard surface coatings to improve the operational life of gate drive teeth  160 . 
     In an embodiment, one or more of drive teeth receiving slots  162  may exhibit a shape generally corresponding to at least a portion of a drive tooth  160 . In other embodiments, one or more of teeth receiving slots  162  may exhibit a generally tapered shape such that gate drive teeth  160  may become wedged within teeth receiving slots  162 . In yet other embodiments, teeth receiving slots  162  may exhibit any suitable shape and/or configuration. 
     Gate drive teeth  160  may be straight, tapered, rounded, and/or may exhibit any suitable shape suitable to fit within teeth receiving slots  162  and/or engage or mesh with worm drive assembly  170  (shown in  FIG. 5 ). For example, gear drive teeth  160  may be generally triangular, generally square, generally rectangular, generally curved, or may exhibit any shape suitable to transmit generally constant angular velocity between gear drive teeth  160  and worm drive assembly  170 . In addition, gear drive teeth  160  may be sized and configured to cooperate with different thicknesses of gate  104  and/or diameter of worm drive assembly  170 . For example, gear drive teeth  160  may be generally elongated to cooperate with a thicker gate  104 . In other embodiments, gear drive teeth  160  may extend along a greater portion of side surface  158  to move gate  104  greater distances to accommodate for a lager orifice  110  and/or gate orifice  156 . 
     In an embodiment, gate drive teeth  160  may be sized and configured to fit into gate  104  with desired tolerances and to be retained in a secure manner. For example, gate  104  may further include a drive teeth retainer  164  on one or both of seating surfaces  154  of gate  104 . Drive teeth retainer  164  may be configured to retain gate drive teeth  160  in position on gate  104 . Drive teeth retainer  164  may be configured as a single piece and/or as a multi-piece system. In another embodiment, one or more of gate drive teeth  160  may include a head portion connected to a shaft portion and a lip extending from the shaft portion opposite the head portion. As shown, the shaft portion and the head portion of gate drive teeth  160  may have similar widths. One or more of teeth receiving slots  162  may include a slot formed therein that is configured to correspond to the lip of the gate drive teeth  160 . When the lip of the gate drive teeth  160  is inserted into the slot of teeth receiving slots  162 , gate drive teeth  160  may be more securely received within teeth receiving slots  162 . 
     Similar to valve assembly, gate  104  may be configured to operate under severe service conditions. For example, gate  104  may include one or more high strength and/or chemical resistant materials. In an embodiment, gate  104  may be formed of steel, galvanized steel, stainless steel, iron, ductile iron, carbon steel, gun metal, alloy steel, alloy steels, one or more metal alloys, one or more polymeric materials, rubber, ceramics, composite materials, brass, combinations thereof, or any other suitable material. Moreover, while valve assembly  100  is described in relation to gate  104  and vice versa, it will be appreciated that any of the gate embodiments described herein may be used with valve assembly  100 . 
     For example,  FIG. 3  is a perspective view of a gate  304  according to another embodiment. Gate  304  has many of the same components and features that are included in gate  104  of  FIG. 2 . Therefore, in the interest of brevity, the components and features of gate  304  and  104  that correspond have been provided with the same or similar reference numbers, and an explanation thereof will not be repeated. However, it should be noted that the principles of gate  304  may be employed with any of the embodiments described with relation to  FIGS. 1A through 2  and vice versa. Gate  304  may include a gate orifice  356  through which process media and/or other materials may flow when gate  304  is in an open position. Gate  304  may further include one or more gate control trim inserts  364  configured to influence flow conditions through gate orifice  356 . For example, gate control trim inserts  364  may be positioned to obstruct a portion of gate orifice  356  thereby reducing the flow area through gate orifice  356 . With a reduced flow area, flow velocity through gate orifice  356  may be increased. Gate control trim inserts  364  may be integral to or removably connected to gate  304 . For example, gate control trim inserts  364  may be selectively inserted in trim insert slots  366  formed in a periphery of gate orifice  356  and a trim insert retainer  368  may be positioned on one or more both of seating surfaces  354  of gate  304  to retain the position of gate control trim inserts  364 . 
     Gate  304  may include a plurality of gate drive teeth  360  extending along at least a portion of a side surface  358  of gate  304 . Similar to gear drive teeth  160 , gear drive teeth  360  may exhibit any suitable shape. For example, in an embodiment, gear drive teeth  360  may include one or more gate drive teeth  360 B including a shaft portion having a width that is less than a width of a head portion of the gear drive teeth  360 B. In other embodiments, gear drive teeth  360  may include one or more gate drive teeth  360 A including a shaft portion having a width that is generally equivalent to or greater than a width of a head portion. In other embodiments, gear drive teeth  360  may include a head portion having a thickness that is greater or less than a thickness of a shaft portion or main body portion of gear drive teeth  360 . In yet other embodiments, gear drive teeth  360  may be generally triangular, generally square, generally rectangular, generally curved, or may exhibit any shape suitable to transmit generally constant angular velocity between gear drive teeth  360  and worm drive assembly  170  (shown in  FIG. 5 ), for example. In addition, gear drive teeth  360  may be sized and configured to cooperate with different thicknesses of gate  304  and/or diameter of worm drive assembly  170 . 
       FIG. 4  is a perspective view of a gate  404  according to another embodiment. Gate  404  has many of the same components and features that are included in gates  104  and  304  of  FIGS. 2 and 3 . Therefore, in the interest of brevity, the components and features of gates  404 ,  304 , and  104  that correspond have been provided with the same or similar reference numbers, and an explanation thereof will not be repeated. However, it should be noted that the principles of gate  404  may be employed with any of the embodiments described with relation to  FIGS. 1A through 3  and vice versa. Gate  404  may have a generally irregular geometric shape configured to efficiently move through valve chamber  112 . For example, moving from the closed position to the open position, a portion of seating surfaces  454  of gate  404  on the side of pivot point shaft receiver  444  opposite a gate orifice  456  formed in gate  404  may be configured to move along an arcuate path to be positioned within the valve chamber  112  of one of valve bonnets  108 . The same movement of gate  404  may also move gate orifice  456  out of the valve chamber  112  of the other valve bonnet  108 . Such a configuration may help reduce the size and weight of valve assembly  400  by limiting the space occupied by gate  404  within valve chamber  112 . 
     Gate  404  may further include a plurality of gate drive teeth  460  extending along at least a portion of a side surface  458  of gate  404 . In an embodiment, gate drive teeth  460  may be configured to engage or mesh with worm gear assembly  170  or any other suitable gear assembly. Gate drive teeth  460  may be formed integral to side surface  458  of gate  304 . Gate drive teeth  460  may be formed in any suitable manner. For example, gate drive teeth  460  may be formed via machining, cutting, laser cutting, molding, or any other suitable technique. 
     Valve assembly  100  may include one or more features configured to move gate  104  between the open and closed positions.  FIG. 5  illustrates a gate drive system  116  according to an embodiment. For example, gate drive system  116  may include worm gear assembly  170  positioned and configured to move gate  104  between the open and closed positions. When worm gear assembly  170  rotates, worm gear assembly  170  may mesh or engage gate drive teeth  160  such that the rotational force from worm gear assembly  170  is transmitted to gate  104  to move gate  104  between the open and closed position. The large contact area between worm gear assembly  170  and gate drive teeth  160  may help increase the strength, force, and/or power of gate  104  as gate  104  moves between the open and closed positions. Such a configuration may help gate  104  shear off process media, residual build-up (e.g., coke), and/or debris that may accumulate on seating surfaces  154  of gate  104  when seating surfaces  154  are positioned within orifice  110 . Worm gear assembly  170  may be a right-hand worm gear assembly, a left-hand worm gear assembly, a single thread worm gear assembly, a multiple thread worm gear assembly, or any other suitable type of worm gear assembly. Moreover, while worm gear assembly  170  is shown and described, in other embodiments, valve assembly  100  may include any type of gear assembly suitable to move gate  104  between the open and closed positions. For example, valve assembly  100  may include a spur gear, a general helical gear, or the like. 
     In an embodiment, an actuator  178  may be connected to an actuator drive shaft  180 , which is attached to worm gear assembly  170 , which is the connection between gate drive system  116  and gate  104 . In other embodiments, actuator  178  may be connected directly to worm gear assembly  170 . Actuator  178  may be configured to control rotation of worm gear assembly  170  to move gate  104  between the open and closed positions. For example, when actuator  170  turns, actuator drive shaft  180  and worm gear assembly  170  are turned to move gate  104  between the open and closed positions. 
     In an embodiment, actuator  178  may comprise an electric multi-turn actuator. Such a configuration may allow gate drive system  116  to generate significant torque while utilizing minimal space. For example, electric multi-turn actuator  178  may be configured to turn worm gear assembly  170  in a first direction and/or a second direction without expansion of electric multi-turn actuator  178 . While an electric multi-turn actuator  178  is described, worm gear assembly  170  may be actuated by various different means. For example, actuation may be hydraulic, electric, pneumatic, manual, electric-hydraulic, combinations thereof, or any other suitable type of actuation. 
     In addition to moving gate  104  between the open and closed positions, worm gear assembly  170 , actuator drive shaft  180 , and/or actuator  178  may be configured to at least partially support gate  104  within valve body  106 . Such a configuration may help reduce loads exerted on pivot point shaft  136  by gate  104 . In addition, such a configuration may help increase the shearing forces or other types of forces created by gate  104  as gate  104  moves between the open and closed positions. 
     Gate drive system  116  may further include a gear box  172  attached to an opening  146  (shown in  FIG. 6 ) in valve body  106 . Gear box  172  may be configured to house at least worm drive assembly  170  and may include one or more gearbox purge ports  176 . As discussed below, gearbox purge ports  176  may be configured to purge, drain, rinse, inspect, and/or perform other maintenance or testing tasks related to gate drive system  116  and/or valve assembly  100 . While gate drive system  116  is shown being attached to valve body  106 , in other embodiments, gate drive system  116  may be positioned within valve assembly  100 . 
       FIG. 6  illustrates valve body  106  according to an embodiment. Valve body  106  may include orifice  110  extending therethrough and at least a portion of valve chamber  112  therein. Valve body  106  may further be configured to receive and retain seat assembly  114  within valve body  106 . In addition, valve body  106  may include one or more features configured to connect valve body  106  to valve bonnets  108 , gate drive system  116 , couplings, pipes, or vessels, and/or other components. For example, valve body  106  may include process mating flanges  120  configured to allow valve body  106  to be connected to process piping, couplings, and/or vessels. In an embodiment, valve body  106  may also include one or more body mating flanges  122  configured to allow valve bonnets  108  to be connected or mated to valve body  106 . As shown, in the illustrated embodiment, body mating flanges  122  may be located on opposite sides of valve body  106 . As discussed in more detail below, each valve bonnet  108  may include a valve bonnet mating flange  124  (shown in  FIG. 8 ) configured to correspond to at least one of body mating flange  122 . Valve body  106  may be connected or mated to valve bonnets  108  in any suitable manner. For example, in an embodiment, valve bonnet mating flanges  124  and body mating flanges  122  may be connected together via mechanical fasteners such as one or more studs  126  and nuts  128  as shown in  FIG. 7 . In an embodiment, a gasket  130  may be positioned between at least one of valve bonnet mating flanges  124  and body mating flanges  122  to form a tight seal between them. In other embodiments, one or both of valve bonnets  108  may be welded to body mating flanges  122 . In yet other embodiments, one or more of valve bonnets  108  may be integral to valve body  106 . In other embodiments, valve bonnet mating flanges  124  and body mating flanges  122  may be connected together via screws, clamps, quick-release clips or the like. Valve body  106  may further include an opening  146  such that gear box  172  may be attached to valve body  106 . 
     Referring again to  FIG. 6 , valve body  106  may further be configured to receive pivot point shaft  136  (shown in  FIG. 1B ). As noted above, pivot point shaft  136  may define the rotation axis or axis of rotation for gate  104 . In an embodiment, pivot point shaft  136  may penetrate through opposite sides of valve body  106  through a pivot point port  138 . In other embodiments, pivot point shaft  136  may penetrate through a single side of valve body  106  or pivot point shaft  136  may not penetrate through any side of valve body  106 . Pivot point port  138  may be sealed with a blind flange (not shown) or a pivot point packing gland  140  configured to prevent pressurized media within valve body  106  from escaping into the atmosphere. For example, in an embodiment, pivot point shaft  136  may be sealed to valve body  106  by pivot point packing gland  140  on one side of valve body  106  and may rotate on a bearing surface associated with blind flange on the opposite side of valve body  106 . In other embodiments, pivot point shaft  136  may be fixedly attached to valve body  106 . As discussed below, pivot point shaft  136  may further be configured to provide visible, exterior indication of the position of gate  104 . 
     Pivot point shaft  136  may be connected to gate  104  in any suitable manner. For example, in an embodiment, pivot point shaft  136  may be connected to gate  104  via pivot point shaft receiver  144  (shown in  FIG. 2 ) formed in gate  104 , key in keyway connection. In other embodiments, pivot point shaft  136  may be connected to gate  104  via a pinned connection, a hinged connection, a ball-joint type connection, a weld, mechanical fasteners, or any other suitable type of connection. In other embodiments, pivot point shaft  136  may be formed integral to gate  104 . 
     Valve body  106  may also include one or more body purge ports  134  configured to purge, drain, rinse, inspect, and/or perform other maintenance or testing tasks related to valve body  106  and/or valve assembly  100 . For example, in an embodiment, a user or operator may utilize body purge ports  134  to remove contamination from valve body  106 . To help gate  104  form a seal or barrier between the upstream and downstream side of valve assembly  100 , valve body  106  and valve bonnets  108  may be frequently purged. Purging means the inside of the unit pressurized to a level higher than that of a process either upstream or downstream, which helps prevent process media from crossing from one side of valve assembly  100  to another. Purge media may take a variety of forms including steam. In an embodiment, valve body  106  may be purged via body purge port  134 . Such a configuration may allow for convenient and safe maintenance, repairs, and/or testing of valve assembly  100  in the field with basic tools and without the need of dissembling valve assembly  100 . 
     Position indication may be accomplished in a variety of different ways.  FIG. 8  illustrates a position indicator  132  according to an embodiment. Position indicator  132  may comprise an arrow  142  or other viewable structure attached to pivot point shaft  136  that is connected to gate  104 . When gate  104  is actuated back and forth, pivot point shaft  136  will rotate with gate  104 . Arrow  142  may be connected to an end portion of pivot point shaft  136  such that arrow  142  is visible on an exterior of valve body  106 . In an embodiment, arrow  142  may be synchronized with indictors on valve body  106  such as “OPEN” and “CLOSED” that display the position of gate  104  or valve assembly  100  relative to being open or closed, or at any point between the open and closed positions. In addition, position indicator  132  may be configured to indicate the position of gate  104  relative to seats  182 ,  184  of seat assembly  114 . 
     In another embodiment, position indicator  132  may include one or more sensors or transducers associated with gate  104 , valve body  106 , and/or seating assembly  114  configured to gather data and transmit signals indicative of the position of gate  104 . The one or more sensors or transducers may include pressure sensors, electromechanical sensors, electronic sensors, flow sensors, motion sensors, combinations thereof, or any other suitable type of sensor. In an embodiment, a computing device or monitoring station may be configured to receive the signals from the sensors and display the position of gate  104  to a user or operator. It will be appreciated that the computing device described herein may include any suitable computing device including personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, combinations thereof, or the like. 
     In an embodiment, the sensors or transducers may be configured to be monitored remotely from one or more different locations. In other embodiments, position indicator  132  may include a mechanical means such as arrow  142  connected to pivot point shaft  136  configured to display the position of gate  104  on valve body  106  combined with one or more sensors that can be monitored remotely. 
     Similar to valve assembly  100 , valve body  106  may be configured to operate under severe service conditions. For example, valve body  106  may include one or more high strength and/or chemical resistant materials. In an embodiment, valve body  106  may be formed of steel, galvanized steel, stainless steel, iron, ductile iron, carbon steel, gun metal, alloy steel, alloy steels, one or more metal alloys, one or more polymeric materials, combinations thereof, or any other suitable material. 
       FIG. 9  illustrates one of valve bonnets  108  according to an embodiment. While only one valve bonnet  108  is shown and described with reference to  FIG. 9 , it should be noted that the principles of the valve bonnet  108  shown in  FIG. 9  may be employed with the other valve bonnet shown in  FIG. 1A . Valve bonnet  108  may include a body mating flange  124  configured to connect or mate with one of body mating flanges  122  of valve body  106 . For example, in an embodiment, valve bonnet mating flanges  124  and body mating flanges  122  may be connected together via mechanical fasteners such as one or more studs  126  and nuts  128 , screws, clamps, quick-release clips or the like. 
     Valve bonnet  108  may be configured to contain severe service pressures. For example, in an embodiment, valve bonnet  108  may include a bonnet shell wall  148  and a plurality of structural stiffeners  150  that in combination or alone may form a pressure containing component configured to resist deformation as a result of elevated temperatures and/or high pressure being exerted on valve bonnet  108 . In other embodiments, the structural stiffeners may be omitted. For example, bonnet shell wall  148  may exhibit a thickness that may help bonnet shell wall  148  withstand or contain elevated temperatures and/or high pressures with or without structural stiffeners  150 . In another embodiment, bonnet shell wall  148  may include one or more materials exhibiting structural properties that may help bonnet shell wall  148  withstand or contain elevated temperatures and/or high pressures with or without structural stiffeners  150 . 
     In an embodiment, an end of one or more of valve bonnets  108  may include a blind flange  152  removably connected to valve bonnet  108 . Blind flange  152  may be connected to valve bonnet  108  by any suitable means. For example, blind flange  152  may be connected to valve bonnet  108  via studs, nuts, and gasket configured to create a tight seal between blind flange  152  and valve bonnet  108 . In other embodiments, blind flange  152  may be connected to valve bonnet  108  via screws, clamps, quick-release clips, or the like. In an embodiment, blind flange  152  may be removed to inspect and/or access components within valve chamber  112 . Such a configuration may allow for convenient and safe maintenance, repairs, and/or testing of valve assembly  100  in the field with basic tools and without the need of dissembling valve assembly  100 . In addition, valve bonnet  108  may include one or more bonnet purge ports  154  configured similar to body purge ports  134  such that valve bonnets  108  and/or valve body  106  may be purged via body purge ports  134  and/or drained, rinsed, inspected, or the like. 
     In an embodiment, valve bonnet  108  may be configured to form a close tolerance fit between an inside wall of valve bonnet  108  and a seating surface  154  of gate  104 . Such a configuration may help ensure that if gate  104  closes while process media and/or other materials are still within a gate orifice  156  formed in gate  104 , the process media and/or other materials do not migrate or deposit inside either of valve bonnets  108  during gate  104  movement. Rather, such process media and/or materials may instead remain in gate orifice  156  until gate  104  moves back into the open position and the process media and/or other materials may be carried downstream by the flow process. 
     Similar to valve assembly  100 , valve bonnets  108  may be configured to operate under severe service conditions. For example, valve bonnets  108  may include one or more high strength and/or chemical resistant materials. In an embodiment, valve bonnets  108  may be formed of steel, galvanized steel, stainless steel, iron, ductile iron, carbon steel, gun metal, alloy steel, alloy steels, one or more metal alloys, one or more polymeric materials, combinations thereof, or any other suitable material. 
       FIG. 10A  illustrates a seat assembly  114  according to an embodiment. As shown, seat assembly  114  may include seats  182 ,  184 . In an embodiment, seats  182 ,  184  may be positioned in valve body  106  and gate  104  may be positioned between seat  182  and seat  184 . Gate  104  may move between the open and closed positions between seats  182 ,  184 . 
     Seats  182 ,  184  may be configured in any suitable manner. For example, seats  182 ,  184  may be configured as ring structures and may be formed of forged steel, galvanized steel, metal alloys, cast iron, ductile iron, cast carbon steel, or other suitable materials. In other embodiments, seats  182 ,  184  may be configured as rectangular plates with apertures formed therein, as annular members, or in any other suitable manner. In other embodiments, seats  182 ,  184  may include one or more semi-rigid and/or flexible materials. In yet other embodiments, at least one of seats  182 ,  184  may be dynamic and/or adjustable based upon a selected application. In an embodiment, seats  182 ,  184  may include one or more rigid materials such that mechanical compression may maintain seats  182 ,  184  in contact with gate  104 . In other embodiments, seats  182 ,  184  may be resiliently forced against gate  104 . For example, in an embodiment, one or more spring members, one or more resilient members, one or more bladders, or the like may resiliently force seats  182 ,  184  against gate  104 . Optionally, seat assembly  114  may include one or more seat retainers  190  configured to retain seats  182 ,  184  within valve body  106 . 
     Seats  182 ,  184  may include seating surfaces  186  configured to contact seating surfaces  154  of gate  104  to form a seal between gate  104  and seats  182 ,  184 . In an embodiment, seating surfaces  186  may be planar, smooth, and/or generally parallel to one another. In other embodiments, seating surfaces  186  may be curved and/or contoured. In other embodiments, at least one of seating surfaces  186  may be angled or tapered relative to the other seating surface  186 . For example, in an embodiment, seating surfaces  186  may be tapered so as to form a wedge-like shape. In an embodiment, one or more of seating surfaces  186  of seats  182 ,  184  may be tapered and one or more of seating surfaces  154  of gate  104  may be planar such that as gate  104  moves over seats  182 ,  184 , gate  104  may become generally wedged between seats  182 ,  184 . In other embodiments, one or more of seating surfaces  154  of gate may be tapered and one or more of seating surfaces  186  of seats  182 ,  184  may be planar. Such a configuration may allow for increased seating and/or sealing force between the seats  182 ,  184  and gate  104  the further gate  104  is rotated over seats  182 ,  184 . 
     Seats  182 ,  184  may exhibit a variety of different configurations. For example, seats  182 ,  184  may include generally planar, generally parallel seating surfaces  186  as shown in  FIG. 10B . In an embodiment, seating surfaces  186  may be beveled. In another embodiment, seats  182 ,  184  may include seating surfaces  186  having a generally planar portion and an angled portion as shown in  FIG. 10C . Moreover, as shown in  FIG. 10C , seats  182 ,  184  may include seat purge channels  188 . In an embodiment, seat purge channels  188  may be configured to help keep seats  182 ,  184  and/or seating surfaces  154  of gate  104  clean by directing one or more bursts of purge media across seats  182 ,  184  and/or seating surfaces  154  of gate  104  as gate  104  moves between the open and closed positions. In an embodiment, as gate  104  moves between the open and closed positions, purge pressure built up within valve assembly  100  is quickly released and flows over seats  182 ,  184  and/or seating surfaces  154  and forces any process media and/or other material off of seats  182 ,  184  and/or seating surfaces  154  and back down a pipeline or the like. In an embodiment, when gate  104  reaches the open and/or closed position, seats  182 ,  184  and seating surfaces  154  may form a seal. Because of the seal, purge pressure within valve assembly  100  may increase to a predetermined purge pressure. In an embodiment, seat purge channels  188  may be operatively connected to body purge ports  134  to control the timing and/or flow of purge media to seats  182 ,  184  and/or valve body  106 . 
     In an embodiment, seats  182 ,  184  may include generally curved seating surfaces  186  as shown in  FIG. 10D . In another embodiment, seats  182 ,  184  may include generally rounded seating surfaces  186  as shown in  FIG. 10E . In yet other embodiments, seats  182 ,  184  may include seating surfaces  186  having a planar portion between a pair of generally rounded portions as shown in  FIG. 10F . In an embodiment, seats  182 ,  184  may include seating surfaces  186  having a curved portion between a pair of angled portions as shown in  FIG. 10G . In yet other embodiments, seats  182 ,  184  may include seating surfaces  186  having a planar portion between a pair of angled portions as shown in  FIG. 10H . 
     Like other components of valve assembly  100 , seats  182 ,  184  may be configured to be compliant with valve standards and codes for different applications or services such as severe service applications. For example, valve body  106  may include one or more high strength and/or chemical resistant materials. In an embodiment, valve body  106  may be formed of steel, galvanized steel, stainless steel, iron, ductile iron, carbon steel, gun metal, alloy steel, alloy steels, one or more metal alloys, one or more polymeric materials, combinations thereof, or any other suitable material. 
       FIG. 11  illustrates support members  118  according to an embodiment. As shown, one or more support members  118  may be integral to or removable from valve bonnets  108  and/or valve body  106 . In an embodiment, support members  118  may be configured to support gear drive system  116  and/or valve assembly  100 . In an embodiment, support members  118  may be configured to stabilize and/or protect gear drive system  116  from impact forces. For example, support members  118  may support legs  118 A and a stabilizer plate  118 B configured to protect gear drive system  116  from heavy equipment or tools accidently hitting valve assembly  100 . In another embodiment, support members  118  may be configured as support legs  118 A configured to support valve assembly  100  such that valve assembly  100  may be positioned vertically for storage and/or transportation. For example, larger valve assemblies (e.g., valve assemblies having orifices exhibiting 48-inch diameters) may be too large to transport on standard 8-ft wide trailers or trucks. By attaching support legs  118  to valve body  106  and/or valve bonnets  108 , valve assembly  100  may be positioned vertically such that larger valve assemblies may fit on standard 8-ft wide trailers, trucks, or the like for transportation. Such a configuration may allow for large valve assemblies to be transported economically by traditional truck, trailer, or other means. 
     Any of the valve assembly embodiments described herein may be utilized in a variety of different isolation and/or control applications. For example, any of the valve assemblies described herein may be utilized in applications such as chemical processing, power generation, petrochemical processing, nuclear power generation, refining, and/or other severe service type applications. Moreover, any of the valve assemblies described herein may be utilized in a variety of non-severe service applications such as fire suppression, agricultural, light industry, or the like. 
     While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting. Additionally, the words “including,” “having,” and variants thereof (e.g., “includes” and “has”) as used herein, including the claims, shall be open ended and have the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”).