Patent Publication Number: US-9845891-B2

Title: Split gate valve with biasing mechanism

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/298,261, entitled “SPLIT GATE VALVE WITH BIASING MECHANISM”, filed Nov. 16, 2011, which is herein incorporated by reference in its entirety, and which claims priority to and benefit of Singapore Patent Application No. 201103281-0, entitled “SPLIT GATE VALVE WITH BIASING MECHANISM”, filed May 9, 2011, which is herein incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to gate valves. More particularly, the present invention relates to a split gate valve employing a biasing mechanism. 
     BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Gate valves are used in a wide variety of industries including oil and gas, power generation, food and beverage, water treatment, and the like. Gate valves include a gate that moves between an open and closed position to control the flow of fluid through the gate valve. In the open position, the gate&#39;s bore is aligned with the flow path, thereby allowing fluid to flow through the gate. To interrupt flow, the gate and, more importantly, the gate&#39;s bore is moved to the closed position, placing the gate&#39;s bore in an unaligned position with the flow path. Gate valves that have large bores (e.g., approximately 5 inches or greater) and/or that operate at higher pressures (e.g., approximately 10,000 psi or greater) generally seal only against one side of the gate. From time to time, operators of the gate may want to test the gate&#39;s seal from both sides. This testing can be more easily conducted if both sides of the gate valve are sealed. Unfortunately, sealing both sides of a large bore and/or high pressure gate valve often requires very high turning force to mechanically open and close the gate valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein: 
         FIG. 1  is a schematic diagram of an embodiment of a split gate valve having a rolling actuator; 
         FIG. 2  is a schematic diagram of another embodiment of the split gate valve having the rolling actuator; 
         FIG. 3  is a schematic diagram of an embodiment of the split gate valve having the rolling actuator disposed within a cavity of the split gate valve; 
         FIG. 4  is a schematic diagram of an embodiment of the split gate valve having the rolling actuator disposed between a pair of gate sections within the cavity of the split gate valve; 
         FIG. 5  is an exploded perspective view of an embodiment of a body of the split gate valve and the pair of gate sections; 
         FIG. 6  is cross-sectional view of an embodiment of the body of the split gate valve with the pair of gate sections inserted within the body, taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 7  is a perspective cutaway view of an embodiment of a ball screw for use as the rolling actuator; 
         FIG. 8  is a perspective cutaway view of an embodiment of a roller screw for use as the rolling actuator; 
         FIG. 9  is a schematic diagram of an embodiment of the split gate valve having expansion bars with the pair of gate sections in an open position; 
         FIG. 10  is a schematic diagram of an embodiment of the split gate valve having the expansion bars with the pair of gate sections in the open position; 
         FIG. 11  is a close-up schematic diagram of an embodiment of the split gate valve of  FIGS. 9 and 10 , illustrating an expansion bar disposed along a slot in the pair of gate sections; 
         FIG. 12  is a schematic diagram of an embodiment of the split gate valve having expansion bars with the pair of gate sections in a closed position; 
         FIG. 13  is a schematic diagram of an embodiment of the split gate valve having the expansion bars with the pair of gate sections in the closed position; 
         FIG. 14  is a close-up schematic diagram of an embodiment of the split gate valve of  FIGS. 12 and 13 , illustrating an expansion bar disposed along a slot in the pair of gate sections; 
         FIG. 15  is a schematic diagram of an embodiment of the split gate valve of  FIG. 14 , illustrating the expansion bar engaging a first portion of a slot along the pair of gate sections as the pair of gate sections move toward a closed position; 
         FIG. 16  is schematic diagram of an embodiment of the split gate valve of  FIG. 15 , taken within line  16 - 16  of  FIG. 14 , illustrating the expansion bar engaging the first portion and a second portion of the slot along the pair of gate sections with the pair of gate sections in a closed position; 
         FIG. 17  is a schematic diagram of an embodiment of the split gate valve of  FIG. 16 , illustrating the expansion bar moved beyond the closed position of  FIG. 16 , causing a spring mechanism (e.g., groove) of the expansion bar to partially compress to prevent buckling of the expansion bar; 
         FIG. 18  is a schematic diagram of an embodiment of the split gate valve of  FIGS. 9-17 , illustrating an expansion bar disposed along a slot in the pair of gate sections in a closed position, wherein the expansion bar has a spring mechanism with a lengthwise groove and crosswise slots; 
         FIG. 19  is a schematic diagram of an embodiment of the split gate valve of  FIG. 18 , illustrating the expansion bar moved beyond the closed position of  FIG. 18 , causing the spring mechanism (e.g., groove and slots) to partially compress to prevent buckling of the expansion bar; 
         FIG. 20  is a perspective view of an embodiment of an expansion bar having a tapered end, a protruding mount (e.g., rectangular lip), and a spring mechanism with a single lengthwise groove; 
         FIG. 21  is a perspective view of an embodiment of an expansion bar having a tapered end, a protruding mount, and a spring mechanism with a lengthwise groove and crosswise slots in a staggered configuration; 
         FIG. 22  is a perspective view of an embodiment of an expansion bar having a tapered end, a protruding mount, and a spring mechanism with a lengthwise groove, lateral notches, and orifices; and 
         FIG. 23  is a perspective view of an embodiment of an expansion bar having a tapered end, a protruding mount (e.g., cylindrical shaft), and a spring mechanism with a single lengthwise groove. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments of the present invention will be described below. These described embodiments are only exemplary of the present invention. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     Certain embodiments discussed below include a system and method that addresses one or more of the above-mentioned inadequacies of a conventional large bore and/or high pressure gate valve. In certain embodiments, a system includes a split gate valve that includes a pair of gate sections (e.g., slab gates) coupled together and configured to move together within a cavity of the split gate valve between an open position and a closed position. The pair of gate sections allows the split gate valve to control flows of two different fluids with each gate section. In addition, the two gate sections allow the isolation of a fluid within a cavity of the split gate valve. The split gate valve also includes a rolling actuator (e.g., a ball screw or roller screw) configured to receive a rotational input (e.g., from a drive) and to convert the rotational input into linear motion to move the pair of gate sections between the open and closed positions. In some embodiments, the pair of split gate sections includes a biasing mechanism (e.g., one or more springs) to bias each gate section of the pair of the gate sections away from each other to form a double seal in the split gate valve. In certain embodiments, the split gate valve includes expansion bars to bias the pair of split gate sections away from each other to form the double seal in the split gate valve. For example, the pair of gate sections forms slots along a length of an interface between the pair of gate sections to engage the expansion bars as the pair of gate sections move from the open position to the closed position. In some embodiments, the expansion bar includes a spring mechanism configured to compress upon moving the pair of gate sections into and beyond the closed position to prevent buckling of the expansion bars. The formation of the double seal allows the filling of the cavity of the split gate valve to test each seal of the double seal at the same time. In certain embodiments, the split gate valve includes a body with an opening (e.g., generally rectangular opening) for the pair of gate sections configured for the insertion of the pair split gate sections and to closely fit the gate sections to minimize deflection. 
       FIG. 1  illustrates an embodiment of a split gate valve  10  having a rolling actuator  12 . Typically, the split gate design limits the use of the split gate valve  10  to valves  10  with smaller bores (e.g., less than approximately 5 inches in diameter) and/or lower pressure ratings (e.g., less than approximately 10,000 psi) due to the amount of force required to move the split gate in large bore and/or high pressure valves  10 . However, the rolling actuator  12  enables the application of less mechanical force or torque to the split gate valve  10  to open and close the valve  10  (i.e., move the gate). Thus, the rolling actuator  12  enables the use of the split gate design with large bore and/or high pressure valves  10  or any other combination of bore size and operating pressure that would require the rolling actuator  12  to reduce the amount of mechanical force or torque needed to open and close the valve  10  (e.g., a smaller bore size with high operating pressure or a larger bore size with a low operating pressure). 
     The split gate valve  10  is generally configured to control a flow of fluid through the split gate valve  10  in various applications. For example, the split gate valve  10  may be employed in applications relating to oil and gas industries, power generation industries, petrochemical industries, and the like. For example, the split gate valve  10  may be coupled to a Christmas tree for petroleum and natural gas extraction. In some embodiments, the split gate valve  10  includes a large bore. For example, the bore of the split gate valve  10  may be at least approximately 5 inches in diameter. In other embodiments, the split gate valve  10  includes a smaller bore. For example, the bore of the split gate valve  10  may be less than approximately 5 inches. The diameter of the bore may range from approximately 3 to 20 inches, approximately 3 to 15 inches, approximately 3 to 10 inches, approximately 10 to 15 inches, or approximately 15 to 20 inches. For example, the bore may be approximately 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 inches, or any other diameter. In certain embodiments, the split gate valve  10  is configured to operate at a high pressure of at least approximately 10,000 pounds per square inch (psi). In other embodiments, the split gate valve  10  is configured to operate at pressure lower than approximately 10,000 psi. For example, the split gate valve  10  may operate at pressures ranging from approximately 5,000 to 30,000 psi or more. By further example, the split gate valve  10  may operate at pressures ranging from approximately 5,000 to 25,000 psi, approximately 10,000 to 20,000 psi, approximately 5,000 to 10,000 psi, approximately 10,000 to 15,000 psi, approximately 15,000 to 30,000 psi, approximately 15,000 to 25,000 psi, approximately 20,000 to 30,000 psi, approximately 20,000 to 25,000 psi, or approximately 25,000 to 30,000 psi. In certain embodiments, the split gate valve  10  may include a bore (e.g., small bore size) of at least approximately 4 inches in diameter and be configured to operate at a pressure (e.g., high pressure) of at least approximately 10,000 psi. In other embodiments, the split gate valve  10  may include a bore (e.g., large bore size) of at least approximately 9 inches in diameter and be configured to operate at a pressure (e.g., low pressure) of at least 5,000 psi. 
     In the illustrated embodiment, the split gate valve  10  includes an actuation system  14  including a drive  16  and the rolling actuator  12 . The actuation system  14  is coupled to a body  18  of the split gate valve  10 . For example, the actuation system  14  may be coupled to a top portion of the body  18  via a bonnet  19 . A bottom portion of the body  18  is also coupled to a bonnet  21 . In certain embodiments, the split gate valve  10  may not include the bonnet  21  attached to the bottom portion of the body  18 . Alternatively, split gate valve  10  may include a single body coupled to the actuation system  14 . The body  18  may be constructed of cast iron, ductile iron, cast carbon steel, gun metal, stainless steel, alloy steels, corrosion resistant alloys, and/or forged steels. The split gate valve  10  includes a gate  20  (e.g., split gate) that include a pair of gate sections  22  and  24  disposed within a cavity  26  of the body  18 , therein the gate sections  22  and  24  are configured to move between an open position and a closed position. As illustrated, the gate  20  is disposed in the closed position. In addition, as illustrated, each gate section  22  and  24  includes a rectangular cross-sectional profile. The body  18  of the split gate valve  10  includes an inlet  28  and an outlet  30  configured for a flow of a fluid through a bore  32  of the body  18  into a passage  34  of the split gate valve  10 . In certain embodiments, the outlet  30  may act as an inlet allowing fluid flow into the cavity  26  from either side of the split gate valve  10 . In some embodiments, the inlet  28  may act as an outlet and the outlet  30  may act as an inlet. As mentioned above, in certain embodiments, the bore  32  may include a diameter  36  of at least approximately 5 inches. For example, the diameter of the bore  32  may range from approximately 5 to 20 inches, approximately 5 to 15 inches, or approximately 5 to 10 inches, or approximately 10 to 15 inches. The passage  34  of the split gate valve  10  includes a passage  38  (indicated by dashes lines) through the gate  20  to allow flow through the split gate valve  10  from the inlet  28  to the outlet  30  when the gate  20  is in an open position (see  FIGS. 2-4 ). 
     The split gate valve  10  is configured to open and close in response to an actuation force from the actuation system  14 . In particular, the drive  16  is configured to provide a rotational input (e.g., rotational force or torque) to the rolling actuator. The drive  16  may be a manual drive or an automatic (e.g., powered) drive. For example, the drive  16  may include a handle or wheel configured to be rotated by an operator. By further example, the drive  16  may include a motor, such as an electric motor, a pneumatic motor, or a hydraulic motor. The rolling actuator  12  is configured to convert the rotational input received by the drive  16  into a linear motion (e.g., linear activation force) to move the gate  20  (i.e., the pair of gate sections  22  and  24 ) between open and closed positions. In certain embodiments, the rolling actuator  12  may include a ball screw or a rolling screw. The rolling actuator  12  is configured to reduce the amount of friction to operate the stem valve  10 . In particular, the rolling actuator  12  reduces the amount of torque or force required to move the gate  20  within the split gate valve  10 . The rolling actuator  12  is coupled to a top portion  40  of the gate  20  via a stem  42  (e.g., an operating stem) configured to facilitate the movement of the gate  20  between the open and closed positions. A bottom portion  44  of the gate  20  is also coupled to a stem  46  (e.g., a balancing stem). The stems  42  and  46  move along bores  45  and  47  of bonnets  19  and  21 , respectively. In certain embodiments, where the split gate valve  18  includes a single body  18 , the stems  42  and  46  may move along bores of the single body  18 . Each of the stems  42  and  46  may be connected to both gate sections  22  and  24  via connectors. For example, both the top portions  40  and the bottom portions  44  of the gate sections  22  and  24  may form cavities to surround a T-connector (see  FIG. 5 ) located at the end of each of the stems  42  and  46  near to the gate  20 . 
     As mentioned above, the gate  20  includes the pair of gate sections  22  and  24  (e.g., slab sections). The split gate arrangement of the gate  20  includes advantages over a single gate arrangement. For example, two different fluids on different sides of the split gate valve  10  may be separated from each other by the pair of gate sections  22  and  24 . Also, a fluid may be pumped into the cavity  26  of the split gate valve  10  for isolation. For example, the cavity  26  may be filled with a fluid (e.g., liquid or gas) to further bias each gate section  22  and  24  away from each other to form seals. In addition, as mentioned above, fluid may be pumped into the cavity  26  from both sides of the split gate valve  10 . Further, each gate section  22  and  24  may be constructed of a different material suitable for the fluid on its respective side of the split gate valve  10 . For example, the material may be corrosion resistant, wear resistant, and/or chemical resistant. The gate sections  22  and  24  may be constructed of cast carbon steel, gun metal, stainless steel, alloy steels, corrosion resistant alloys, and/or forged steels. Also, as discussed in greater detail below, gate sections  22  and  24  form a double seal which allows the testing of each seal at the same time (i.e., simultaneously). 
     As to the details of the split gate arrangement of the gate  20 , the pair of gate sections  22  and  24  include a biasing mechanism  48  disposed between them. The biasing mechanism  48  is configured to bias the gate sections  22  and  24  away from each other in directions  50  and  52 , respectively. Each gate section  22  and  24  is biased against a seat  54  (e.g., annular seat) of the body  18  of the split gate valve  10  to form a double seal (i.e., a seal on each side of the valve  10 ). The seat  54  may be constructed of ceramic, cast iron, ductile iron, cast carbon steel, gun metal, stainless steel, alloy steels, corrosion resistant alloys, and/or forged steels. As illustrated, the biasing mechanism  48  includes a spring  56 . In other embodiments, the biasing mechanism  48  may include a cam mechanism or an elastic material. The formation of a seal by each gate section  22  and  24  allows seal testing for each gate face (i.e., the inlet  28  and outlet  30  sides) to occur at a valve rated working pressure during the introduction of a test pressure into the cavity  26  of the seat valve  10 . 
     The pair of gate sections  22  and  24  also includes a coupling mechanism  58  to couple the gate sections  22  and  24  together. Due to the coupling mechanism  58 , the gate sections  22  and  24  are configured to move together within the cavity  26  of the split gate valve  10  between the open and closed positions. In particular, in response to a rotational input provided by the drive  16 , the rolling actuator  12  converts the rotational input into a linear motion that jointly moves the coupled gate sections  22  and  24  between the open and closed positions. In certain embodiments, the coupling mechanism  58  may include a pin extending into slots with each gate section  22  and  24 . The coupling mechanism  58  guides the movement of the gate sections  22  and  24  away and toward one another. In particular, the coupling mechanism  58  guides movement of the gate sections  22  and  24  towards the seat  54  in response to biasing force of biasing mechanism  48  (e.g., spring). The split gate valve  10  as described above allows rolling friction (via the rolling actuator  12 ) to reduce the work required to mechanically operate the valve  10 , in particular, large bore and/or high pressure gate valves  10 . 
       FIG. 2  illustrates an embodiment of the split gate valve  10  in an open position. As illustrated, the passage  38  through the gate  20  (i.e., gate sections  22  and  24 ) is aligned with the bore  32  of the inlet  28  and the outlet  30  to form the passage  34  through the split gate valve  10 . The split gate valve  10  is as described in  FIG. 1  except for an added gear box  68  in the actuation system  14 . The gear box  68  is disposed between the drive  16  and the rolling actuator  12 . The gear box  68  is configured to reduce the amount of rotational torque used to move the gate  20  (i.e., gate sections  22  and  24 ) between the open and closed positions. For example, the gear box  68  may include internal gearing coupled to the drive  16 . For example, the internal gearing may include gear ratios ranging from 4:1 to 20:1. As described above, the rolling actuator  12  converts the rotational input from the drive  16  and the gear box  68  into a linear motion to move the pair of gate sections  22  and  24  between open and closed positions. The split gate valve  10  as described allows rolling friction (via the rolling actuator  12 ) to reduce the work required to mechanically operate the valve  10 , in particular, large bore and/or high pressure gate valves  10 . 
       FIGS. 3 and 4  illustrate embodiments of the actuation system  14  of the split gate valve  10 . The split gate valve  10  is as described in  FIG. 1  except that the rolling actuator  12  is disposed within the cavity  26  of the split gate valve  10 . The rolling actuator  12  may be disposed within the cavity  26  of the split gate valve  10  when the environment within the cavity  26  is suitable for the actuator  12 . In embodiment of  FIG. 3 , the rolling actuator  12  is disposed within the cavity  26  coupled to the stem  42  (e.g., the operating stem) outside of the gate sections  22  and  24 . In the embodiment of  FIG. 4 , the rolling actuator  12  is disposed within the cavity  26  coupled to the stem  42  between the gate sections  22  and  24 . In the embodiments of both  FIGS. 3 and 4 , as above, the rolling actuator  12  converts the rotational input from the drive  16  into a linear motion to move the pair of gate sections  22  and  24  between open and closed positions. The split gate valve  10  as described allows rolling friction (via the rolling actuator  12 ) to reduce the work required to mechanically operate the valve  10 , in particular, large bore and/or high pressure gate valves  10 . 
       FIG. 5  illustrates a perspective view of an embodiment of both the body  18  and the gate sections  22  and  24  for the split gate valve  10 . As illustrated, the body  18  includes a cuboidal shape with a plurality of faces  78  (e.g., six). For example, the body  18  may be shaped as a right cuboid, a rectangular box, a rectangular hexahedron, a right rectangular prism, square cuboid, square box, or right square prism. Alternatively, the body  18  may include a circular, oval, or oblong shape. As illustrated, the body  18  includes a pair of opposite faces  78  (e.g., face  80 ) including large bores  32  for the passage of fluid through the split gate valve  10 . In certain embodiments, the bore  32  includes diameter  36  that may be at least approximately 5 inches in diameter. In some embodiments, the bore  32  includes diameter  36  that may be less than approximately 5 inches. The diameter  36  may range from approximately 3 to 20 inches, approximately 3 to 15 inches, or approximately 3 to 10 inches, or approximately 10 to 15 inches, or approximately 15 to 20 inches. For example, the diameter  36  may be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 inches, or any other diameter therebetween. 
     In addition, the body  18  includes a pair of opposite faces  78  (e.g., face  82 ) that each includes an opening  84  configured for the insertion of the pair of gate sections  22  and  24  along a length  86  of the gate sections  22  and  24 . As illustrated, the opening  84  includes a rectangular perimeter  88  with rounded corners  90 . In other embodiments, the perimeter  88  of the opening  84  may be rectangular with right-angled corners  90 , square with rounded corners  90 , or square with right-angled corners  90 . Alternatively, the perimeter  88  of the opening  84  may be circular, round, oval, or oblong. In particular, the perimeters  88  of the opening  84  and the cavity  26  of the body  18  are configured to closely fit around the gate  20  when the gate  20  is inserted within the body  18 . Thus, cavity  26  of the body  18  is configured to allow the gate  20  to consume nearly all of the space within the cavity  26 . In particular, gate  20  engages substantially the entire cavity  26 . Tightly fitting the cavity  26  of the body  18  to the gate  20  allows the reduction in size of the body  18  (i.e., reduction in material) minimizing the amount of deflection experienced by the split gate valve  10  under load pressure. In addition, using the generally rectangular opening  84  adds more material between the gate  20  and the body  18  (e.g., thicker walls) to increase the strength and rigidity of the body  18  as opposed to a circular opening. In other words, the rectangular opening  84  allows thicker walls surrounding the gate  20  that otherwise would be cut away with a circular opening. However, as mentioned above, the opening  84  may be circular, round, oval, or oblong as long as the shape meets the design criteria for the split gate valve  10  such as fitting the gate  20  and the seat  54 . 
     The shape of the perimeter  88  of the opening  84  and the cavity  26  depends on a cross-sectional area of the gate  20  along a width  92  of the gate  20 . As illustrated, each gate section  22  and  24  includes a main body  94  with a generally rectangular shape along the length  86  of the sections  22  and  24 . In addition, each gate section  22  and  24  includes ends  96  and  98  and sides  100  and  102  that taper away from the main body  94 . In certain embodiments, each gate section  22  and  24  may include flat ends  96  and  98  and flat sides  100  and  102 . End  96  forms a cavity  99  to surround a T-connector located at the end of the stem  42 . End  98  also forms a cavity (not shown) to surround a connector (e.g., T-connector) located at the end of the stem  44 . Further, each gate section  22  and  24  includes an opening  104 , defining passage  38  through the gate  20 , configured to allow the flow of fluid through the gate  20  when the gate  20  is aligned with the bore  32  of the body  18 . In some embodiments, the opening  104  of each gate section  22  and  24  may include a diameter  106  equivalent to the diameter  36  of the bore  32  of the body  18 . In other embodiments, the diameter  105  of the opening  104  of each gate section  22  and  24  may be smaller than the diameter  36  of the bore  32  of the body  18 . 
       FIG. 6  illustrates the close fit between the body  18  and the gate  20  upon insertion of the gate  20  into the body  18 . In particular,  FIG. 6  is a cross-sectional view of the body  18  disposed about the gate  20  taken along line  6 - 6  of  FIG. 5 . The body  18  and the gate  20  are as described in  FIGS. 1 and 5 . In particular, the gate sections  22  and  24  are inserted within the opening  84  into the cavity  26  of body  18  with the length of 86 of the gate  20  crosswise (i.e. perpendicular) to the flow into passage  34  through the inlet  28  and outlet  30  of the body  18 . The perimeter  88  of the cavity  26  and the opening  84  closely fit around both gate sections  22  and  24 , thus, the gate  20  takes up most of the space within the cavity  26  of the body  18 . In addition, as described above, the gate sections  22  and  24  may include at least one biasing mechanism  48  disposed between them to bias each gate section  22  and  24  away from each other to form a double seal (e.g., seals  116  and  118 ) with the seat  54  of the body  18 . 
     As mentioned above, these embodiments of the body  18  and gate  20  are employed with the actuation system  14  that includes the rolling actuator  12  to reduce the work required to mechanically operate the valve  10  (via rolling friction), in particular, large bore and/or high pressure gate valves  10 .  FIGS. 7 and 8  illustrate some, but not all, of the embodiments of the rolling actuator  12 .  FIG. 7  illustrates an embodiment of the rolling actuator  12  that includes a ball screw  128 . Although  FIG. 7  illustrates one embodiment of the ball screw  128 , the ball screw  128  may include any type of ball screw mechanism. The ball screw  128  may be a part of or separate from the stem  42  (e.g., the operating stem) of the split gate valve  10 . The illustrated ball screw  128  includes a screw shaft  130  including helical grooves  132  and a nut  134  including a plurality of ball bearings  136 . The helical grooves  132  provide a pathway for the ball bearings  136  to travel along as the nut  134  receives a rotational input as indicated by arrow  138 . The ball screw  128  may include a recirculation mechanism to recirculate the ball bearings  136  into the helical grooves  132 . The ball screw  128  is configured to convert the rotational input  138  into a linear motion as indicated by arrow  140 , while minimizing friction to provide a high mechanical efficiency. The ball screw  128  may be constructed of chrome steel, stainless steel, and/or alloy steels. The ball bearings  136  may be constructed of chrome steel, stainless steels, alloy steels, and/or ceramic. 
     Alternatively,  FIG. 8  illustrates the rolling actuator  12  including a roller screw  150 . Although  FIG. 8  illustrates one embodiment of the roller screw  150 , the roller screw  150  may include any type of roller screw mechanism. For example, the roller screw  150  may include a planetary roller screw, an inverted roller screw, a recirculating roller screw, or a bearing ring roller screw. The roller screw  150  may be part of or separate from the stem  42  (e.g., the operating stem) of the split gate valve  10 . The roller screw  150  includes a screw shaft  152  including helical grooves  154  and a nut  156  including a plurality of rollers  158  disposed between opposite rings (e.g., ring  160 ). Each roller  158  may be threaded (e.g., threads  162 ) or grooved. The helical grooves  154  provide a pathway for the threaded or grooved rollers  158  to travel along as the nut  156  receives a rotational input as indicated by arrow  138 . The roller screw  150  is configured to convert the rotational input  138  into a linear motion as indicated by arrow  140 , while minimizing friction to provide a high mechanical efficiency. The roller screw  150  may be constructed of chrome steel, stainless steel, and/or alloy steels. As mentioned above, the rolling actuator  12  (e.g., the ball screw  128  or the roller screw  150 ) is configured to reduce friction and to covert rotational input (e.g., received by the drive  16 ) into linear motion to move the pair of gate sections  22  and  24  between the open and closed positions within the split gate valve  10 . Thus, the rolling actuator  12  reduces the work required to mechanically operate the split gate valve  10 , in particular, large bore and/or high pressure gate valves  10 . 
     As discussed in detail above, the biasing mechanism  48  (e.g., spring) is disposed between the pair of gate sections  22  and  24  in a relatively central location, e.g., between lateral sides. However, the biasing mechanism  48  may be disposed at any location suitable to bias the gate sections  22  and  24  away from one another. Furthermore, the biasing mechanism  48  may include any biasing structure suitable to impart an expanding biasing force, e.g., opposite outward force, to force the gate sections  22  and  24  away from one another. For example, as discussed in detail below with reference to  FIGS. 9-23 , the biasing mechanism may include a wedge-like structure, a cam mechanism, or the like, to gradually expand the gate sections  22  and  24  apart. In certain embodiments, the biasing mechanism may include an expansion bar, such as a wedge bar or tapered structure, with one or more spring elements. Accordingly, the expansion bar may be described as a spring bar, a spring-equipped expansion bar, or an integral spring wedge bar. As discussed below, the spring elements may be configured to absorb any overextension or overstroking of the gate sections  22  and  24 , thereby preventing buckling or permanent deformation of the gate sections  22  and  24 . 
     As illustrated in  FIGS. 9-23 , the split gate valve  10  includes one or more expansion bars  168  (e.g., a pair of expansion bars  168 ) to bias the gate sections  22  and  24  away from one another toward opposite seats  54  of the split gate valve  10 . As the gate sections  22  and  24  are energized by the expansion bars  168  to expand or diverge away from one another, the gate sections  22  and  24  interface with the opposite seats  54  to seal both gate sections  22  and  24  with the body  18  of the split gate valve  10 . In the embodiments discussed below, the expansion bars  168  are disposed in slots along opposite lateral sides of the gate sections  22  and  24 . However, the expansion bars  168  may be disposed in any suitable location to expand the gate sections  22  and  24 . In addition, the expansion bars  168  include biasing mechanisms, which are described in greater detail below, to prevent the expansion bars  168  from buckling or permanently deforming due to overstroking of the split gate valve  10 . For example, embodiments of the expansion bars  168  include integral spring mechanisms, such as longitudinal grooves, crosswise slots or notches, and/or orifices, which are compressible in one or more directions (e.g., lengthwise and/or crosswise directions). This compressibility of the integral spring mechanisms enables the expansion bars  168  to absorb any overextension or overstroking of the gate sections  22  and  24  beyond the closed position of the split gate valve  10 . 
       FIGS. 9 and 10  are schematic diagrams of different views of an embodiment of the split gate valve  10  having expansion bars  168  (e.g., first expansion bar  170  and second expansion bar  172 ) with the pair of gate sections  22  and  24  in the open position.  FIG. 9  illustrates a front view of the gate  20  and  FIG. 10  illustrates a side view of the gate  20 . The split gate valve  10 , which is described above, includes the actuation system  14  as described above. In addition, the structure of the split gate valve  10  is as described above. The expansion bars  168  are configured to bias the gate sections  22  and  24  away from one another to seal against the opposite seats  54  of the split gate valve  10  as the pair of gate sections  22  and  24  moves from the open position to the closed position. Each expansion bar  168  includes a first end  174 , a second end  176 , and a spring mechanism  177  disposed along a portion of a length of the expansion bar  168  between the first and second ends  174  and  176 . The spring mechanism  177  is configured to compress upon movement of the pair of gate sections  22  and  24  into and beyond the closed position (e.g., absorbing any compression caused by overextension or overstroking) to prevent buckling of the expansion bar  168 . As illustrated, the spring mechanism  177  includes a groove  179  configured to compress upon movement of the pair of gate sections  22  and  24  into and beyond the closed position to prevent buckling of the expansion bar  168 . In certain embodiments, each expansion bar  168  may include more than one spring mechanism  177  as described in greater detail below. 
     The first end  174  includes a protruding end  178  configured to engage the body  18  of the split gate valve  10  to maintain the expansion bar  168  in a stationary position relative to the pair of gate sections  22  and  24 . As illustrated, the protruding end  178  includes a lip that rests on a retention recess  180  (e.g., slot) of the body  18 . In certain embodiments, the protruding end  178  may include different shapes as described in greater detail below. The bonnet  19  secured to the body  18  holds the expansion bars  168  in place. Alternatively, the expansion bars  168  may be secured to any stationary part (e.g., body  18  or bonnet  19 ) of the split gate valve  10  via a pin, bolt, or weld. 
     As illustrated in  FIG. 10 , the pair of gate sections  22  and  24  form a slot  182  (e.g., slot sections  181  and  183 ) along the longitudinal interface between the gate sections  22  and  24  on each lateral side of the gate sections  22  and  24 . Collectively, each pair of slot sections  181  and  183  of the respective gate sections  22  and  24  define a respective slot  182 . Each slot  182  is configured to engage a respective expansion bar  168  as the pair of gate sections  22  and  24  move from the open position to the closed position. Each expansion bar  168  is configured to form an interference fit or wedge fit with each slot  182  upon moving the pair of gate sections  22  and  24  into the closed position as described in greater detail below. In particular, the second end  176  of each expansion bar  168  includes a tapered end  184  configured to engage the slot  182  as the pair of gate sections  22  are moved from the open position to the closed position, and to bias the gate sections  22  and  24  away from one another as the tapered end  184  gradually expands the slot  182 . 
       FIG. 11  is a close-up schematic diagram of an embodiment of one of the expansion bars  168  and the pair of gate sections  22  and  24  of the split gate valve  10  of  FIGS. 9 and 10 . The expansion bar  168  and slot  182  are as described above in  FIGS. 9 and 10 . Again, each slot  182  is defined by slot sections  181  and  183  in the respective gate sections  22  and  24 . As illustrated, a width  194  of the expansion bar  168  is initially less than a width  196  of the slot  182  while the gate sections  22  and  24  are in an open position. Thus, in the open position, the gate sections  22  and  24  more easily move along the expansion bar  168 , which is not yet biasing the gate sections  22  and  24  apart from one another. For example, the difference in widths  194  and  196  may provide a small clearance to reduce friction, and improve movement, of the gate sections  22  and  24  relative to the expansion bar  168 . However, as the gate sections  22  and  24  move toward the closed position, the expansion bar  168  gradually fills and expands the width  196  of the slot  182  (e.g., in a wedge-like manner) to create a biasing force to spread apart the gate sections  22  and  24 . For example, upon engagement between the tapered end  184  of the expansion bar  168  and the slot  182 , the tapered end  184  gradually wedges, expands, or spreads the gate sections  22  and  24  apart (i.e., in opposite diverging directions) from one another. The width  194  of the expansion bar  168  is uniform from the first end  174  toward the second end  176  of the expansion bar  168 , where the width  194  begins to narrow forming the tapered end  184  of the expansion bar  168 . 
     Similarly, the slot  182  includes a first slot portion  198  with a uniform width  196  and a second slot portion  199  that tapers or converges. For example, the second slot portion  199  includes first and second portions  200  and  202  that taper or converge toward an interface  204  between the pair of gate sections  22  and  24 . In addition, the first and second portions  200  and  202  taper or converge in a direction from the top portion  40  to the bottom portion  44  of the gate sections  22  and  24 . For example, the first portion  200  includes a first angle  206  relative to a longitudinal axis  208  of the expansion bar  168  and the gate  20 . The first angle  206  may range from approximately 0 to 40 degrees, 10 to 30 degrees, 15 to 25 degrees, or 10 to 20 degrees. For example, the first angle  206  may be approximately 5, 10, 15, 20, 25, 30, 35, or 40 degrees, or any other angle therebetween. The second portion  202  includes a second angle  210  relative to the longitudinal axis  208  of the expansion bar  168  and the gate  20 . The second angle  210  may range from approximately 0 to 40 degrees, 10 to 30 degrees, 15 to 25 degrees, or 10 to 20 degrees. For example, the second angle  210  may be approximately 5, 10, 15, 20, 25, 30, 35, or 40 degrees, or any other angle therebetween. In certain embodiments, the first and seconds angles  206  and  210  are the same. In some embodiments, the first and second angles  206  and  210  are different from each other. The first and second angles  206  and  210  are configured to control the rate of expanding the gate sections  22  and  24  away from one another as the gate sections  22  and  24  move lengthwise along the expansion bars  168 . Therefore, different angles  206  and  210  provide different rates for expanding the gate sections  22  and  24  away from one another. In certain embodiments, the first and second portions  200  and  202  of the slot  182  may be curved to provide a continuously variable rate of expanding the gate sections  22  and  24 . 
     As mentioned above, the second end  176  of the expansion bar  168  includes the tapered end  184  configured to engage the slot  182  as the pair of gate sections  22  and  24  move from the open position to the closed position and to bias the gate sections  22  and  24  away from one another as the tapered end  184  engages the slot  184 . In particular, the tapered end  184  of the expansion bar  168  is configured to wedgingly engage the first and second portions  200  and  202  of the slot  182  to form an interference fit between the expansion bar  168  and the slot  182  and to bias the gate sections  22  and  24  away from one another. Specifically, tapered end  184  may taper at an angle  212  relative to the axis  208 , thereby enabling the tapered end  184  to form an interference fit or wedge fit with the first and second portions  200  and  202  and bias the gate sections  22  and  24  away from one another. The angle  212  may range from approximately 5 to 40 degrees, 10 to 30 degrees, 15 to 25 degrees, or 10 to 20 degrees. For example, the angle  212  may be approximately 5, 10, 15, 20, 25, 30, 35, or 40 degrees, or any other angle therebetween. In certain embodiments, the angle  212  of the tapered end  184  may be the same as angles  206  and  210  of the slot  182 . In some embodiments, the angle  212  may be different from angles  206  and  210  of the slot  182 . For example, the angle  212  may be greater or less than the angle  206  and/or  210  of the slot  182 . In one embodiment, the angle  210  may be greater than the angle  206 , while the angle  212  may be greater than, less than, or equal to either the angle  206  or the angle  210 . In another embodiment, the angle  210  may be less than the angle  206 , while the angle  212  may be greater than, less than, or equal to either the angle  206  or the angle  210 . As illustrated, the gate sections  22  and  24  are located in the open position. In the open position, the expansion bar  168  does not wedgingly engage the slot  182  to bias the gate sections  22  and  24  away from one another. 
       FIGS. 12 and 13  are schematic diagrams of different views of an embodiment of the split gate valve  10  having expansion bars  168  (e.g., first expansion bar  170  and second expansion bar  172 ) with the pair of gate sections  22  and  24  in the closed position.  FIG. 12  illustrates a front view of the gate  20  and  FIG. 13  illustrates a side view of the gate  20 . The split gate valve  10  in  FIGS. 12 and 13  is as described in  FIGS. 9-11  except the gate  20  is positioned in the closed position. As mentioned above, the expansion bars  168  remain in a stationary position, while the gate sections  22  and  24  move relative to the expansion bars  168 . As illustrated in  FIG. 13 , the tapered end  184  of the expansion bar  168  wedgingly engages the slot  182  formed by the pair of gate sections  22  and  24  to form an interference fit and bias the gate sections  22  and  24  away from each other to seal against opposite seats  54  of the split gate valve  10 . 
       FIG. 14  is a close-up schematic diagram of an embodiment of one of the expansion bars  168  and the pair of gate sections  22  and  24  of the split gate valve  10  of  FIGS. 13 and 14 . The expansion bar  168  and slot  182  are as described above in  FIGS. 9-11 . As illustrated, the tapered end  184  of the expansion bar  168  forms an interference fit or wedge fit with the slot  182  to bias the gate sections  22  and  24  away from each other. In particular, with the gate  20  in the closed position, the tapered end  184  wedgingly engages both the first portion  200  and second portion  202  of the slot  182  as described in greater detail below. In certain embodiments, the expansion bar  168  may bias the gate sections  22  and  24  approximately 1 to 200 mils (25.4 to 5,080 microns), 5 to 90 mils (127 to 2,286 microns), or 10 to 50 mils (254 to 1,270 microns) away from each other, as indicated by gap  205 . However, the expansion bars  168  may bias the gate sections  22  and  24  apart by any gap  205  to provide positive sealing with the seats  54 . 
       FIGS. 15-17  describe the interaction between the tapered end  184  of the expansion bar  168  and the slot  182  as the gate  20  moves from the open position to the closed position as indicated by arrows  214 .  FIG. 15  is a schematic diagram of an embodiment of the expansion bar  168  engaging the first portion  200  of the slot  182  formed between the gate sections  22  and  24  as the gate sections  22  and  24  move  214  toward the closed position. As illustrated, when the gate sections  22  and  24  move  214  toward the closed position, the tapered end  184  of the expansion bar  168  first engages the first portion  200  of the slot  182 . The engagement of the first portion  200  of the slot  182  with the tapered end  184  of the expansion bar  168  energizes the expansion bar  168 . In addition, this engagement forms an interference fit, as indicated by arrows  222 , between the tapered end  184  of the expansion bar  168  and the slot  182 . For example, as the tapered end  184  of the expansion bar  168  gradually fills and exceeds the width of the slot  182  along portions  200  of the slot  182  (e.g., the interference fit), the tapered end  184  gradually increases the biasing force in opposite directions to bias the gate sections  22  and  24  away from one another. In response to this biasing force, the gate sections  22  and  24  gradually move apart to seal against the opposite seats  54  of the split gate valve  10 . As discussed above, the first portion  200  has an angle  206  (see  FIG. 11 ), which may be equal, less than, or greater than angle  210  of the second portion  202 . The angle  206  defines a first or initial rate of expansion between the gate sections  22  and  24  as the gate  20  moves  214  toward the closed position. 
       FIG. 16  is schematic diagram of an embodiment of the expansion bar  168  engaging the first and second portions  200  and  202  of the slot  182  formed between the pair of gate sections  22  and  24  with the pair of gate sections  22  in the closed position, taken within line  16 - 16  of  FIG. 14 . As illustrated, as the gate sections  22  and  24  continue to move  214  toward the closed position, the tapered end  184  of the expansion bar  168  engages the second portion  202  of the slot  182 . The second portion  202  has the angle  210  (see  FIG. 11 ) to define the second rate of expansion between the gate sections  22  and  24  as the gate  20  moves  214  toward the closed position. Again, the angle  210  may be equal, less than, or greater than the angle  206 . Therefore, the second rate of expansion along the second portion  202  of the slot  182  may be equal, greater than, or less than the first rate of expansion. In reaching the closed position, the tapered end  184  biases the gate sections  22  and  24  away from one another. The engagement of the second portion  202  of the slot  182  with the tapered end  184  of the expansion bar  168  forms an interference fit, as indicated by arrows  232 , between the tapered end  184  and the slot  128  to further bias the gate sections  22  and  24  away from one another in addition to the bias provided by the first portion  200  with the tapered end  184 . In response to this biasing force, the gate sections  22  and  24  gradually move apart to seal against the opposite seats  54  of the split gate valve  10 . 
     In certain situations, the split gate valve  10  may be overstroked (e.g., overextended) resulting in the gate  20  moving beyond the closed position.  FIG. 17  is a schematic diagram of an embodiment of the expansion bar  168  engaging the first and second portions  200  and  202  of the slot  182  formed between the pair of gate sections  22  and  24 , illustrating the gate  20  moved beyond the closed position.  FIG. 17  is as described in  FIG. 16  except for the state of the spring mechanism  177  (e.g., groove  179 ). In response to the gate  20  being moved beyond the closed position, the spring mechanism  177  compresses to prevent buckling of the expansion bar  168 . As illustrated in  FIG. 17 , the spring mechanism  177  is narrower than in  FIGS. 15 and 16  due to axial forces  242  applied to the tapered end  184  of the expansion bar  168 , as the gate  20  moves beyond the closed position. As the axial forces  242  engage the tapered end  184 , the forces  242  impart opposite lateral forces  244  inwardly against the spring mechanism  177  (e.g., groove  179 ). Thus, the expansion bar  168  compresses laterally (e.g., crosswise to axis  208 ). By acting as a spring, the spring mechanism  177  absorbs the additional force preventing damage to expansion bar  168 , still enabling the expansion bar  168  to bias the gate sections  22  and  24  away from one another to seal against the opposite seats  54  of the split gate valve  10 . In certain embodiments, a width  246  of the groove  179  may be compressed to approximately 0 to 100, 5 to 90, 10 to 80, 20 to 70, 30 to 60, or 40 to 50 percent of its original width  246  as a result of the forces  242  and  244 . 
     Besides the spring mechanism  177  disposed along a portion of the length of the expansion bar  168  between the first and second ends  174  and  176 , the expansion bar  168  may include additional or alternative spring mechanisms.  FIG. 18  is a schematic diagram of an embodiment of the expansion bar  168  having a spring mechanism  252  at an attached end (e.g., first end  174 ) with the expansion bar  168  engaging the first and second portions  200  and  202  of the slot  182  formed between the pair of gate sections  22  and  24  with the pair of gate sections  22  and  24  in the closed position. The gate  20  and the expansion bar  168  are as described in  FIG. 14  except the expansion bar  168  includes the spring mechanism  252 . The spring mechanism  252  is disposed between the first end  174  of the expansion bar  168  and the spring mechanism  177  (e.g., groove  179 ). The spring mechanism  252  is configured to compress upon forcing the gate  20  (i.e., gate sections  22  and  24 ) to move beyond the closed position, thereby preventing buckling of the expansion bar  168 . As illustrated, the spring mechanism  252  includes a plurality of slots  254  in a staggered arrangement along the longitudinal axis  208  of the expansion bar  168 . The slots  254  compress axially (e.g., lengthwise along axis  208 ), whereas the groove  179  compresses laterally (e.g., crosswise to axis  208 ). The slots  254  may be oriented crosswise (e.g. perpendicular) to the longitudinal axis  168 . The slots  154  extend across a portion of the width  194  of the expansion bar  168  from sides  251  and  253  of the expansion bar  168 . The number of slots  254  may range from 2 to 20, 2 to 10, or 2 to 6. For example, the expansion bar  168  may include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 slots  254 . Each of the slots  254  includes a width  256 . In certain embodiments, the width  256  of the slots  254  may be the same. In other embodiments, the width  256  of slots  254  may vary between one another. 
     As mentioned above, in certain situations, the split gate valve  10  may be overstroked resulting in the gate  20  moving beyond the closed position.  FIG. 19  is a schematic diagram of an embodiment of the expansion bar  168  in  FIG. 18  engaging the first and second portions  200  and  202  of the slot  182  formed between the pair of gate sections  22  and  24 , illustrating the pair of gate sections  22  and  24  moved beyond the closed position.  FIG. 19  is as described in  FIG. 18  except for the state of the spring mechanism  252  (e.g., slots  254 ). As mentioned above, in response to the gate  20  being moved beyond the closed position, the spring mechanism  177  compresses to prevent buckling of the expansion bar  168 . Similarly, the spring mechanism  177  compresses to prevent buckling of the expansion bar  168 . As a result, the width  256  of the slots  254  narrows in response to the axial forces  242  applied to the expansion bar  168  due to moving the gate  20  beyond the closed position. In certain embodiments, the width  256  of each slot  254  may be compressed to approximately 0 to 100, 5 to 90, 10 to 80, 20 to 70, 30 to 60, or 40 to 50 percent of its original width  256 . By acting as a spring, the spring mechanism  252  absorbs the additional force due to overstroking (e.g., overextending) the split gate valve  10  and prevents damage to the expansion bar  168 . 
       FIGS. 20-23  illustrate different embodiments of the expansion bar  168 , which are each configured to bias the gate sections  22  and  24  away from one another upon moving the gate  20  to the closed position. The different features of the embodiments of the expansion bars  168  described below may be used in any combination with one another. Each expansion bar  168  includes the first end  174  having the protruding end  178  and the second end having the tapered end  178 , and the spring mechanism  177  (e.g., groove  179 ) as described above.  FIG. 20  is a perspective view of an embodiment of the expansion bar  168  having a single spring mechanism  177  (e.g., groove  179 ). As mentioned above, the spring mechanism  177  is configured to compress (e.g., groove  179  narrows) upon moving the gate  20  (e.g., gate sections  22  and  24 ) into and beyond the closed position, thereby preventing buckling of the expansion bar  168 . In addition, the protruding end  178  of the expansion bar  168  includes a lip  266  configured to engage the body  18  of the split gate valve  10  to maintain the expansion bar  168  in a stationary position relative to the pair of gate sections  22  and  24 . For example, the lip  266  may rest in the retention recess  180  of the body  18 . 
     Alternatively, the expansion bar  168  may include more than one spring mechanism.  FIG. 21  is a perspective view of an embodiment of the expansion bar  168  having multiple spring mechanisms  177  and  252  (e.g., groove  179  and slots  254 , respectively). As mentioned above, the spring mechanism  252  is disposed between the first end  174  of the expansion bar  168  and the spring mechanism  177  (e.g., groove  179 ). The spring mechanism  252  is configured to compress (e.g., slots  254  narrow) upon moving the gate  20  (i.e., gate sections  22  and  24 ) into and beyond the closed position, thereby preventing buckling of the expansion bar  168 . As illustrated, the spring mechanism  252  includes the plurality of slots  254  in a staggered arrangement along the longitudinal axis  208  of the expansion bar  168 . The slots  154  extend across a portion of the width  194  of the expansion bar  168  from sides  251  and  253  of the expansion bar  168 . The number of slots  254  may range from 2 to 20, 2 to 10, or 2 to 6. For example, the expansion bar  168  may include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 slots  254 . Each of the slots  254  has the width  256 . In certain embodiments, the width  256  of the slots  254  may be the same. In other embodiments, the width  256  of slots  254  may vary between one another. In addition, the expansion bar  168  includes the lip  266  as described above. 
       FIG. 22  is a perspective view of an embodiment of the expansion bar  168  having multiple spring mechanisms  177  and  252  (e.g., groove  179 , orifices  276 , and notches  278 ). The spring mechanism  252  is disposed between the first end  174  of the expansion bar  168  and the spring mechanism  177  (e.g., groove  179 ). The spring mechanism  252  is configured to compress upon moving the gate  20  (i.e., gate sections  22  and  24 ) into and beyond the closed position, thereby preventing buckling of the expansion bar  168 . As illustrated, the spring mechanism  252  includes a plurality of orifices  276  aligned along the longitudinal axis  208  between the sides  251  and  253  of the expansion bar  168 . The number of orifices  276  may range from 1 to 10. For example, the expansion bar  168  may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or any other number of orifices  276 . The size of each orifice  276  may be the same or vary between one another. The spring mechanism  252  also includes a plurality of notches  278  arranged between the plurality of orifices  276 . In certain embodiments, the plurality of notches  278  may be aligned with the plurality of orifices  276 . The notches  278  extend across a portion of the width  194  from the sides  251  and  253  of the expansion bar  168 . The number of notches  278  may range from 2 to 20, 2 to 10, or 2 to 6. For example, the expansion bar  168  may include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 notches  278 . As illustrated, the notches  278  include a curved notch. In some embodiments, the shape of the notch  278  may include a square notch, wedge-shaped notch, rectangular shaped notch, or any other shape, or any combination of shapes thereof. The plurality of orifices  276  and the plurality of notches  278  shrink or compress upon moving the gate  20  (e.g., gate sections  22  and  24 ) into and beyond the closed the closed position, thereby preventing buckling of the expansion bar  168 . In addition, the expansion bar  168  includes the lip  266  as described above. 
     The expansion bar  168  may also include an alternative protruding end  178 .  FIG. 23  is a perspective view of an embodiment of the expansion bar  168  having a cylindrical configuration of the protruding end  178 . The expansion bar  168  includes a single spring mechanism  177  (e.g., groove  179 ). As mentioned above, the spring mechanism  177  is configured to compress upon moving the gate  20  (e.g., gate sections  22  and  24 ) into and beyond the closed position, thereby preventing buckling of the expansion bar  168 . In addition, the protruding end  178  of the expansion bar  168  includes a cylindrical protrusion  288 , such as a pin or bolt, configured to engage the body  18  of the split gate valve  10  to maintain the expansion bar  168  in a stationary position relative to the pair of gate sections  22  and  24 . For example, the cylindrical protrusion  288  may rest on or in the retention recess  180  of the body  18 . Alternatively, the cylindrical protrusion  288  may be inserted within a hole of the body  18  or bonnet  19 . In certain embodiments, protrusion  288  may include an alternative cross-sectional shape including a triangular, square, rectangular, or any other shape. 
     As discussed above, the disclosed embodiments include the split gate valve  10  that includes the pair of gate sections  22  and  24  (e.g., slab gates) coupled together and configured to move together within the cavity  26  of the split gate valve  10  between open and closed positions. The split gate valve  10  includes the rolling actuator  12  to reduce the amount of mechanical force or torque required to move the split gate between the open and closed positions in large bore and/or high pressure valves. In addition, the gate sections  22  and  24  form a double seal against the seat of  54  of the split gate valve  10 . Further, the split gate valve  10  includes one or more expansion bars  168  to bias the gate sections  22  and  24  away from one another via slots  182  formed on the gate  20 , as the gate  20  moves toward the closed position. The expansion bars  168  may include one or more spring mechanisms configured to compress upon moving the gate  20  into and beyond the closed position to prevent buckling of the expansion bars  168 . The pair of gate sections  22  and  24  also enables the split gate valve  10  to control flows of two different fluids with each gate section  22  and  24 . In addition, the double seal enables the isolation of a fluid within the cavity  26  of the split gate valve  10 . Further, the double seal enables testing of each seal at the same time by filling the cavity of the split gate valve  10  with a fluid. In certain embodiments, the body  18  of the split gate valve  10  includes a rectangular opening configured to tightly fit the gate  20  allowing a reduction in size of the body  18 , thus, minimizing the amount of deflection experienced by the split gate valve  10  under load pressure. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.