Patent Publication Number: US-9903482-B2

Title: Ball valve stem retaining system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/673,959 entitled “Ball Valve Stem Retaining System”, filed on Nov. 9, 2012, which is herein incorporated by reference in its entirety, which is a continuation in part of U.S. patent application Ser. No. 12/553,037, entitled “Ball Valve Stem Retaining System”, filed Sep. 2, 2009, which is herein incorporated by reference in its entirety. 
    
    
     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. 
     Ball valves may be employed to regulate a flow of fluid in a variety of applications. Ball valves typically include a body, a ball disposed within the body, and a stem rotationally coupled to the ball. During ball valve maintenance, the stem may be removed to service various components within the ball valve, such as bushings, bearings and seals. Unfortunately, certain ball valves may need to be disassembled prior to removal of the stem. Due to the large number of fasteners typically employed within a ball valve, such disassembly may be both expensive and time-consuming. Consequently, maintenance operations may be performed at longer than desired intervals, resulting in inefficient valve operation. 
    
    
     
       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 perspective view of a ball valve having an internally retained stem configured to be removed without separating closures from the body in accordance with certain embodiments of the present technique; 
         FIG. 2  is a cross-section of an exemplary ball valve, taken along line  2 - 2  of  FIG. 1 , in accordance with certain embodiments of the present technique; 
         FIG. 3  is an exploded view of internal components within an exemplary ball valve, as shown in  FIG. 1 , in accordance with certain embodiments of the present technique; 
         FIG. 4  is a detailed cross-section of an exemplary ball valve, taken within line  4 - 4  of  FIG. 2 , in accordance with certain embodiments of the present technique; 
         FIG. 5  is a cross-section of an exemplary ball valve, taken along line  5 - 5  of  FIG. 1 , in accordance with certain embodiments of the present technique; 
         FIG. 6  is an exploded view of an exemplary ball valve, as shown in  FIG. 1 , in accordance with certain embodiments of the present technique; 
         FIG. 7  is a detailed cross-section of an alternative ball valve in accordance with certain embodiments of the present technique; 
         FIG. 8  is a perspective view of a ball valve having an internally retained stem configured to be removed without separating closures from the body in accordance with certain embodiments of the present technique; 
         FIG. 9  is a cross-section of an exemplary ball valve, taken along line  9 - 9  of  FIG. 8 , in accordance with certain embodiments of the present technique; 
         FIG. 10  is a detailed cross-section of an exemplary ball valve, taken within line  10 - 10  of  FIG. 9 , in accordance with certain embodiments of the present technique; 
         FIG. 11  is a perspective view of an exemplary stem of the ball valve of  FIGS. 8-10 , in accordance with certain embodiments of the present technique; 
         FIG. 12  is a perspective view of an exemplary ball of the ball valve of  FIGS. 8-10 , in accordance with certain embodiments of the present technique; and 
         FIG. 13  is an exploded cross-section of an exemplary ball valve, as shown in  FIGS. 8-12 , in accordance with certain embodiments of the present technique. 
     
    
    
     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. 
     Embodiments of the present disclosure may significantly reduce the duration and costs associated with ball valve maintenance operations by providing an internally retained stem that may be removed from the valve without uncoupling the closures. As will be appreciated, ball valves may include stems that are internally or externally retained. Externally retained stems include certain features external to the valve body configured to restrict movement of the stem away from the ball during operation. For example, certain externally retained stems include a ridge disposed about the circumference of the stem. Movement of the stem away from the ball is blocked by contact between the ridge and a plate bolted to the body. To extract the stem for maintenance, the plate may be unbolted and removed. Unfortunately, ball valves including externally retained stems are expensive to manufacture due to the additional parts associated with retaining the stem and configuring the valve body to accommodate the stem retention plate. Additionally, during disassembly and repair operations, residual fluid pressure within the valve may cause the stem to be ejected from the valve at high speed when the plate is unbolted and removed. 
     Alternatively, ball valves may include internally retained stems. In such valves, the stem may include a ridge disposed about the circumference of the stem, similar to the externally retained stems. However, movement of the stem away from the ball is blocked by contact between the ridge and an inner surface of the valve body. In this configuration, the stem may not be removed by extracting the stem in a direction away from the valve. Instead, the stem may be removed by translating the stem into the body. Unfortunately, because the ball is disposed within the body, the ball must be removed prior to extracting the stem. The process of removing the ball generally involves uncoupling at least one closure, each closure being disposed to opposite longitudinal ends of the body. Due to the large number of fasteners that secure the closures to the body, this process may be time-consuming and expensive. 
     Consequently, the disclosed embodiments include an internally retained stem configured to pass through at least one opening within the ball. In this manner, the stem may be removed from the valve without uncoupling the closures from the body. Specifically, certain embodiments include a stem having a retainer disposed about a circumference of the stem. The retainer is configured to block inward movement of the stem via contact between the retainer and an outer surface of the body. Upon removal of the retainer, the stem may be either removed through the ball and a fluid passage of the valve, or the stem may be removed through an opposite side of the valve (i.e., in a crosswise direction relative to the fluid passage). In either configuration, the duration and costs associated with ball valve maintenance are substantially reduced, because the closures may remain coupled to the body. 
       FIG. 1  is a perspective view of a ball valve  10  configured to regulate a flow of fluid. As illustrated, the ball valve  10  includes a body  12  (e.g., hollow cylindrical body), a first closure  14  and a second closure  16 . The closures  14  and  16  are configured to seal the body  12  and secure the valve  10  to fluid conduits. The closures  14  and  16  are coupled to the body  12  by multiple fasteners  18 . In the present configuration, each fastener  18  includes a threaded rod (e.g., bolt) disposed within a complementary threaded recess within the body  12 . The threaded rods pass through openings within the closures  14  and  16 , and are secured by nuts. The nuts serve to securely fasten the closures  14  and  16  to the body  12 . As will be appreciated, the number of fasteners  18  may be selected to provide a proper seal between the closures  14  and  16  and the body  12 . Specifically, the fasteners  18  are configured to substantially reduce the formation of gaps between the closures  14  and  16  and the body  12  that may cause fluid to leak from the valve  10 . For example, in certain embodiments, each closure  14  and  16  may be coupled to the body  12  by more than 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more fasteners  18 . In an alternative embodiment, the closures  14  and  16  are secured to the body  12  by a welded connection. In such an embodiment, the fasteners  18  may be omitted. 
     Each closure  14  and  16  includes multiple openings  20  configured to couple each closure  14  and  16  to a fluid conduit. As will be appreciated, fasteners may pass through the openings  20  and corresponding openings within respective conduits to secure the closures  14  and  16  to the conduits. The number of openings may be selected to substantially reduce the possibility of fluid leakage between the closures  14  and  16  and the conduits. For example, the closures  14  and  16  may include more than 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more openings  20 . 
     As discussed in detail below, the valve  10  includes a ball configured to rotate from an open position to a closed position. The ball includes a bore that facilitates the passage of fluid through the valve  10 . In the open position, the bore of the ball is aligned with a bore of each closure  14  and  16  such that fluid may pass through the valve  10 . In the closed positioned, the bore is rotated perpendicular to the closures  14  and  16 , thereby substantially blocking the passage of fluid through the valve  10 . As will be appreciated, rotating the ball to an orientation between the open and closed positions may establish a desired flow rate of fluid through the valve  10  by adjusting the fluid passage area. The ball is rotationally coupled to a stem  22  such that rotation of the stem  22  causes the ball to rotate. Furthermore, the stem  22  is coupled to an adapter plate  24  configured to mount with a variety of valve control components. For example, the adapter plate  24  may be mounted to an electric or hydraulic actuator configured to remotely control the position of the ball within the valve  10 . Alternatively, the adapter plate  24  or stem  22  may be coupled to a handle such that the valve  10  may be operated manually. 
     As discussed in detail below, the stem  22  is configured to be removed from the valve  10  without uncoupling the closures  14  and/or  16  from the body  12 . Due to the large number of fasteners  18  that couple the closures  14  and  16  to the body  12 , the process of removing the closures  14  and  16  may be time-consuming. Consequently, the stem  22  of the present embodiment may be removed from the valve  10  without uncoupling the fasteners  18 . Specifically, the stem  22  may be retained by a removable retainer configured to block inward movement of the stem  22 . Once the retainer has been removed, the stem  22  may pass through the body  12  and enter the ball. Because the length of the stem  22  is limited with respect to an inner diameter of the ball, the stem  22  may be removed through either closure  14  or  16 . For example, the length of the stem  22  may be less than the inner ball diameter. Alternatively, the length of the stem  22  may be limited such that it may enter the ball at an angle (i.e., canted orientation). This removal process may significantly reduce the time associated with stem removal, thereby significantly reducing the cost of maintenance operations. 
       FIG. 2  is a cross-section of an exemplary ball valve  10 , taken along line  2 - 2  of  FIG. 1 . As illustrated, the valve  10  is in the open position, thereby facilitating a flow of fluid  26  in an axial direction  27 . Specifically, the fluid enters a bore  28  of the first closure  14 , flows through a bore  32  of a ball  30 , and exits a bore  34  of the second closure  16 . As previously discussed, the ball  30  may rotate about a radial axis  36  to regulate the flow of fluid  26  through the valve  10 . Rotating the ball  30  varies the flow area between the bore  32  and the closures  14  and  16 , thereby adjusting the flow rate of fluid  26 . To facilitate rotation of the ball  30 , the stem  22  is rotationally coupled to the ball  30  by dowels  38 . While two dowels  38  are illustrated in the present embodiment, it should be appreciated that more or fewer dowels  38  may be employed in alternative embodiments. For example, certain embodiments may include 1, 2, 3, 4, 5, 6, 7, 8, or more dowels  38  disposed about the stem  22  in a circumferential direction  39 . In an alternative embodiment, the stem  22  may be rotationally coupled to the ball  30  by a spline connection. 
     The ball  30  includes a first trunnion  40  that extends in the radial direction  36 . The first trunnion  40  is configured to mount within a first trunnion block  42 . Similarly, the ball  30  includes a second trunnion  41  disposed within a second trunnion block  43 . The trunnion blocks  42  and  43  serve to orient the ball  30  within the body  12 . As discussed in detail below, the trunnion blocks  42  and  43  are secured to the body  12  and include openings  47  and  49  configured to receive the first trunnion  40  and second trunnion  41 , respectively. Specifically, the trunnions  40  and  41  have circular cross-sections configured to mount within circular openings  47  and  49  within the trunnion blocks  42  and  43 . Because the trunnion blocks  42  and  43  are secured to the body  12 , the ball  30  may rotate within the trunnions  40  and  41  when driven to rotate by the stem  22 . To facilitate rotation, a first trunnion bearing  44  is disposed between the first trunnion  40  and the opening  47  within the first trunnion block  42 , and a second trunnion bearing  45  is disposed between the second trunnion  41  and the opening  49  within the second trunnion block  43 . As will be appreciated, the bearings  44  and  45  may reduce rotational resistance of the ball  30 . 
     During operation of the valve  10 , the stem  22  is retained such that movement along the radial direction  36  is blocked. Specifically, movement of the stem  22  along an outward radial direction  46  away from the ball  30  is blocked by contact between the stem  22  and the body  12 . In other words, the stem  22  is internally retained by the body  12 . As will be appreciated, fluid pressure within the ball  30  may exert a force on the stem  22  in the direction  46 . For example, the fluid pressure may be approximately between 0 to 15,000, 0 to 5625, 0 to 3750, 0 to 2000, or about 0 to 290 psi. In certain embodiments, the area of the stem  22  exposed to the fluid within the ball  30  may be approximately between 0.5 to 4, 1 to 3, or about 2 square inches. Therefore, if the pressure within the ball  30  is approximately 4000 psi and the area of the stem  22  is approximately 2 square inches, the fluid may exert a force of approximately 8000 pounds on the stem  22  in the direction  46 . Consequently, the present embodiment includes a thrust bushing  48  and thrust washer  50  to facilitate rotation of the stem  22  relative to the body  12  despite the large contact force between the stem  22  and the body  12 . As discussed in detail below, the thrust bushing  48  and thrust washer  50  are disposed about the circumference of the stem  22  between a raised portion (not shown) of the stem  22  and the body  12 . 
     Furthermore, the stem  22  is retained along an inward radial direction  52  by a retainer  54  (e.g., c-shaped retainer). As discussed in detail below, the retainer  54  is disposed within a recess (e.g., annular groove) of the stem  22 , and contacts an outer surface of the body  12 , thereby blocking movement of the stem  22  in the inward radial direction  52 . As will be appreciated, other retention configurations, such as snap-type rings or fixed collars, among others, may be employed in alternative configurations. In further embodiments, the stem  22  may be retained by contact between one or more seals disposed between the stem  22  and body  12 . During maintenance operations, the adapter plate  24  may first be removed from the valve  10 , thereby exposing the retainer  54 . Because the stem  22  is internally retained, the stem  22  may remain secured within the valve  10  despite removal of the adapter plate  24 . The retainer  54  may then be removed to enable the stem  22  to move in the direction  52 . Once the stem  22  is entirely within the bore  32  of the ball  30 , the stem  22  may be extracted from the valve  10  through the first closure  14  or the second closure  16 . In this manner, the stem  22  may be removed from the valve  10  without removal of the ball  30 , the first closure  14 , or the second closure  16 . As previously discussed, because removing the closures  14  and/or  16  may involve uncoupling a large number of fasteners  18 , the present embodiment may reduce the duration of maintenance operations compared to configurations in which the closures  14  and/or  16  are removed to facilitate extraction of the stem  22 . Furthermore, as illustrated, the valve  10  includes grease injection ports  56  disposed within each closure  14  and  16  to provide lubricating grease to various components within the valve  10 . 
       FIG. 3  is an exploded view of internal components within an exemplary ball valve  10 , as shown in  FIG. 1 . As illustrated, the ball  30  is oriented in an open position such that fluid  26  may flow through the bore  32 . In the present embodiment, a seat  58  (e.g., annular seal) is disposed on each end of the bore  32  to provide a seal between the ball  30  and the closures  14  and  16 . Specifically, in the open position, the seats  58  provide a seal between the bore  32  and the bores  28  and  34  of the closures  14  and  16 , respectively. Conversely, in the closed position, the seats  58  provide a seal between the ball  30  and the bores  28  and  34  of the closures  14  and  16 , respectively. This configuration may substantially reduce or eliminate fluid leakage within the valve  10 . 
     As previously discussed, the trunnion bearing  44  is disposed about the trunnion  40  to facilitate rotation of the ball  30  within the body  12 . As illustrated, the trunnion bearing  44  is disposed between the trunnion  40  and the opening  47  within the trunnion block  42 . As will be appreciated, the outer diameter of the bearing  44  may be substantially similar to the inner diameter of the opening  47 . Similarly, the inner diameter of the bearing  44  may be substantially similar to the outer diameter of the trunnion  40 . This configuration may both tightly secure the ball  30  within the valve  10 , and enable the ball  30  to rotate with respect to the trunnion block  42 . The trunnion block  42  is rigidly mounted within the body  12 . As illustrated, the trunnion block  42  includes two tapered sections  62  configured to substantially match the inner contours of the cylindrical body  12 . Because the dimensions of the ball  30  are configured to position the trunnion blocks  42  and  43  against the inner surface of the body  12 , the tapered sections  62  serve to limit movement of the trunnion blocks  42  and  43  relative to the body  12 . In addition, the trunnion block  42  includes recesses  64  configured to receive pins extending from the closures  14  and  16 . These pins serve to further limit movement of the trunnion block  42 . While one recess  64  is illustrated on one axial side of the trunnion block  42  in the present embodiment, it will be appreciated that a similar recess  64  may be disposed on the opposite axial side. Furthermore, alternative embodiments may include more or fewer recesses  64  configured to engage respective pins. For example, certain embodiments may include 1, 2, 3, 4, 5, 6, or more recesses  64  disposed on each axial side of the trunnion block  42 . Furthermore, a similar pin and recess configuration may be employed on the second trunnion block  43 . 
     As previously discussed, the dowels  38  may serve to rotationally couple the stem  22  to the ball  30 . Specifically, the stem  22  includes recesses  66  configured to receive the dowels  38 . As illustrated, a diameter of the recesses  66  may substantially coincide with a diameter of the dowels  38  such that the dowels  38  may mount securely within the recesses  66 . The ball  30  includes a similar pair of corresponding recesses  68  disposed within an opening  69 , and configured to receive the dowels  38 . Similar to the recesses  66 , a diameter of the recesses  68  may substantially coincide with the diameter of the dowels  38 . In this configuration, when the dowels  38  are disposed within the recesses  66  and  68 , the stem  22  may be rotationally coupled to the ball  30  such that rotation of the stem  22  induces the ball  30  to rotate. 
     Furthermore, the thrust bushing  48  and thrust washer  50  are illustrated. As previously discussed, the thrust bushing  48  and thrust washer  50  are disposed about the stem  22  and facilitate rotation of the stem  22 . In addition, the retainer  54  is also disposed about the stem  22  and limits movement of the stem  22  in the inward radial direction  52 . In the present embodiment, the retainer  54  is a two-piece split ring having a first c-shaped segment  70  and a second c-shaped segment  72 . As will be appreciated, further embodiments may include other retainer configurations such as split rings having three or more segments, dowels, pins, fasteners or other suitable retainer configurations. As discussed in detail below, the ring segments  70  and  72  may be disposed within an annular recess of the stem  22 . In such a configuration, contact between the retainer  54  and the body  12  may block movement of the stem  22  in the inward radial direction  52 . However, once the ring segments  70  and  72  have been removed, the stem  22  may pass through the body  12 , trunnion block  42 , trunnion  40 , and into the bore  32  of the ball  30 . Because the length of the stem  22  may be less than an inner diameter of the ball  30 , the stem  22  may be positioned entirely within the ball  30  after the retainer  54  has been disengaged. Consequently, the stem  22  may be removed from the valve  10  without uncoupling the closures  14  and/or  16 . In this manner, maintenance operations may be performed on the stem  22 , seals, bushings, washers or other components within the valve  10  in less time than maintenance operations on a valve configuration in which the closures  14  and/or  16  are removed prior to servicing the internal valve components. 
       FIG. 4  is a detailed cross-section of an exemplary ball valve  10 , taken within line  4 - 4  of  FIG. 2 . As previously discussed, movement of the stem  22  along the outward radial direction  46  is blocked by contact between the stem  22  and an inner surface  74  of the body  12 . Specifically, the thrust bushing  48  and thrust washer  50  transfer the outward load from the stem  22  to the body  12  via contact with the inner surface  74 . Conversely, movement of the stem  22  in the inward radial direction  52  is blocked by contact between the retainer  54  and an outward surface  76  of the body  12 . Specifically, the first ring segment  70  and the second ring segment  72  of the retainer  54  are disposed within an annular recess  71  of the stem  22 . Consequently, contact between the recess  71 , the retainer  54  and the outer surface  76  of the body  12  blocks radial movement of the stem  22 . 
     In the illustrated embodiment, the stem  22  includes a flange  78  configured to block a flow of fluid between the ball  30  and the stem  22 . As previously discussed, the fluid pressure within the ball  30  exerts a force on the stem  22  in the direction  46 . Consequently, the force is resisted by contact between the stem  22  and the body  12  via the thrust bushing  48  and thrust washer  50 . In addition, a gap  77  is provided between the stem flange  78  and ball  30  such that the stem  22  does not apply a force to the ball  30  in the direction  46 . As will be appreciated, if a substantial force is applied to the ball  30  in the direction  46 , the ball  30  may become misaligned within the body  12 , thereby establishing leaks within the seats  58  or other components of the valve  10 . Therefore, the gap  77  facilitates movement of the stem  22  in the direction  46  without varying the alignment of the ball  30 . In addition, an o-ring or other seal  80  is provided within a recess  81  of the flange  78 . The seal  80  may serve to further block the flow of fluid from the ball  30 . 
     Similar to the seal  80  within the flange  78 , other seals may be provided to block fluid from flowing between the ball  30  and the stem  22 . Specifically, an o-ring or other seal  82  may be disposed within a recess  83  of the stem  22 . The seal  82  may block fluid from passing between the stem  22  and body  12 . In addition, another o-ring or other seal  84  may be disposed within a recess  85  of the adapter plate  24 . The seal  84  may block fluid from passing between the adapter plate  24  and the body  12 . Furthermore, an o-ring or other seal  86  may be disposed within a recess  87  of the stem  22 . The seal  86  may block fluid from passing between the stem  22  and the adapter plate  24 . The combination of these seals may serve to substantially reduce or eliminate fluid leakage from the valve  10 . In addition, in the event of leakage, the seals  84  and  86  may be easily replaced by removal of the adapter plate  24  as a temporary repair without disassembly of the valve  10 . 
     In certain configurations, the seals  80 ,  82 ,  84  and  86  may be rubber o-rings. As will be appreciated, rubber may degrade over time, thereby reducing the effectiveness of the seals. Consequently, the seals may be periodically replaced to ensure proper valve integrity and operation. While the seals  84  and  86  may be accessed by removing the adapter plate  24 , seals  80  and  82  may not be accessible without removal of the stem  22 . As previously discussed, the stem  22  may be removed by extracting the ring segments  70  and  72  from the recess  71 . The stem  22  may then be moved along the direction  52  into the bore  32  of the ball  30 . At that point, the stem  22  may be removed from the valve  10  without uncoupling the closures  14  and/or  16 , thereby decreasing the duration of maintenance operations compared to configurations in which the ball  30  is removed to access the stem  22 . After the stem  22  has been removed, the seals  80  and  82  may be replaced, thereby ensuring proper operation of the ball valve  10 . 
       FIG. 5  is a cross-section of an exemplary ball valve  10 , taken along line  5 - 5  of  FIG. 1 . As illustrated, the stem  22  includes a raised portion  88  positioned at an inward side (i.e., along the inward radial direction  52 ) of the stem  22  adjacent to the flange  78 . A diameter  90  of the raised portion  88  is larger than a diameter  92  of an outward portion (i.e., along the outward radial direction  46 ) of the stem  22 . The difference in diameters  90  and  92  establishes a ridge  94  (e.g., annular abutment surface) that extends about the stem  22  in the circumferential direction  39 . Due to the radial position (i.e., position along the radial direction  36 ) of the ridge  94 , the recesses  66  configured to receive the dowels  38  form gaps within the ridge  94 . Consequently, the ridge  94  is not visible in  FIG. 2  (i.e., the cross-section taken along line  2 - 2  of  FIG. 1 ). The ridge  94  serves to establish a mounting point for the thrust bushing  48  and thrust washer  50 . Specifically, force applied to the stem  22  in the direction  46  due to fluid pressure within the ball  30  is resisted by contact between the ridge  94  and the thrust bushing  48 . The thrust bushing  48 , in turn, applies a force to the thrust washer  50 , which is resisted by contact with the inner surface  74  of the body  12 . In this manner, any force applied to the stem in the direction  46  is transferred from the stem  22  via the ridge  94  to the body  12 . This configuration blocks movement of the stem  22  in the direction  46  even when the retainer  54  has been removed. Consequently, the stem  22  may not be ejected from the valve  10  during maintenance operations due to residual fluid pressure within the ball  30 . However, once the retainer  54  has been removed, the stem  22  may move in the inward radial direction  52  and enter the ball  30 . As previously discussed, because the length of the stem  22  is limited with respect to a diameter of the bore  32 , the stem  22  may be removed from the valve  10  without uncoupling the closures  14  and/or  16 , thereby significantly reducing the duration and costs associated with maintenance operations. Furthermore, as illustrated, the valve  10  includes a vent  96  configured to release pressure within the valve  10  prior to removing the stem  22 . 
       FIG. 6  is an exploded view of an exemplary ball valve  10 , as shown in  FIG. 1 , illustrating the steps of removing the stem  22  from the valve  10 . First, the adapter plate  24  is uncoupled from the valve  10  and moved in the direction  46  to expose the retainer  54 . As previously discussed, in the present embodiment, the retainer is a two-piece split ring including the first segment  70  and the second segment  72 . As illustrated, the first segment  70  may be removed from the groove  71  along the direction  98 , and the second segment  72  may be removed from the groove  71  along the direction  100 . With the retainer  54  uncoupled from the stem  22 , the stem  22  may move in the inward radial direction  52  into the bore  32  of the ball  30 . As illustrated, a length  102  of the stem  22  is less than a diameter  104  of the bore  32 . In addition, the length  102  is selected such that the stem  22  may be positioned within the bore  32  without contact between the stem  22  and the bore  32  despite an outward end (i.e., end along the outward radial direction  46 ) of the stem  22  having a diameter  106  and an inward end (i.e., end along the inward radial direction  52 ) of the stem  22  having a diameter  108 . In other words, the length  102  is selected such that the stem  22  having particular dimensions may fit within the bore  32  of the ball  30 . In this manner, the stem  22  may be removed from the valve  10  by moving the stem in the axial direction  27  through either closure  14  or  16 . In this manner, the stem  22  may be removed from the valve  10  without uncoupling the closures  14  and/or  16  from the body  12 , thereby reducing the duration and costs associated with valve maintenance. 
     When the stem  22  passes through the body  12  and into the bore  32  of the ball  30 , the seals  80 ,  82 , and  86  may remain attached to the stem  22 . Specifically, seal  80  may remain within the recess  81 , seal  82  may remain within the recess  83 , and seal  86  may remain within the recess  87 . In this manner, the seals  80 ,  82 , and  86  may be easily removed from the stem  22  and replaced during the maintenance operation. In addition, removal of the stem  22  may cause the dowels  38  to enter the bore  32 , either individually or attached to the stem  22 . The dowels  38  may also be removed from the bore  32  through the closures  14  and/or  16 . To reassemble the valve  10 , the dowels  38  may be disposed within the recesses  66  of the stem  22 . The stem  22  may then be aligned with the first trunnion  40  and moved into operating position along the direction  46 . The retainer segments  70  and  72  may then be disposed within the recess  71 , thereby securing the stem  22  to the body  12 . Finally, the adapter plate  24  may be moved into position along the direction  52 . In this manner, the stem  22  may be installed within the valve  10  without uncoupling either closure  14  or  16  from the body  12 . Due to the large number of fasteners  18  associated with the closures  14  and  16 , removing and installing the stem  22  without uncoupling the closures  14  and/or  16  may significantly reduce the duration and costs associated with valve maintenance operations. 
       FIG. 7  is a detailed cross-section of an alternative ball valve  10 , including a different stem configuration. Specifically, the stem  22  in the illustrated embodiment omits the flange  78 , seal  80  and recess  81  illustrated in the embodiment described with regard to  FIG. 4 . In the present configuration, the diameter  90  of the raised portion  88  is substantially equal to a diameter  110  of the opening  69 . Consequently, fluid flow from the ball  30  may be blocked by contact between the stem  22  and the opening  69 . Alternatively, pressure between the valve cavity (e.g., area between the ball  30  and body  12 ) and the bore  32  may equalize when the valve is open because the seal  80  is omitted. As will be appreciated, because the present configuration does not include the flange  78 , manufacturing costs associated with machining the stem  22  may be reduced. However, in the illustrated embodiment, the stem  22  may be removed from the valve  10  in a similar manner to the procedure described above with regard to  FIG. 6 . Specifically, the adapter plate  24  may be removed, exposing the retainer  54 . Removal of the retainer  54  facilitates movement of the stem  22  in the direction  52 . Because the diameter  90  of the raised portion  88  is substantially equal to the diameter  110  of the opening  69 , the stem  22  may pass through the opening  69  and into the ball  30 . Consequently, the stem  22  may be removed without uncoupling the closures  14  and  16 , thereby reducing the duration and costs associated with valve maintenance operations. 
       FIG. 8  is a perspective view of a ball valve  210  configured to regulate a flow of fluid. As illustrated, the ball valve  210  includes a housing  212  (e.g., two-piece housing) having a closure  214  (e.g., a first closure) coupled to a body  216  (e.g., a main body or second closure). Although the illustrated housing  212  is a two-piece housing, other embodiments of the housing  212  may include a one-piece housing or a multi-piece housing having 3, 4, 5, or more sections. The closures  214  and  216  are configured to seal the housing  212  and secure the valve  210  to fluid conduits. The closures  214  and  216  are coupled together by multiple fasteners  218 . In the present configuration, each fastener  218  includes a threaded rod (e.g., bolt), which extends through an opening in the closure  214  and into a complementary threaded recess within the body or closure  216 . The threaded rods are then secured by nuts, thereby securing the closure  214  to the body or closure  216 . As will be appreciated, the number of fasteners  218  may be selected to provide a proper seal between the closures  214  and  216 , thereby sealing the valve  210 . Specifically, the fasteners  218  are configured to substantially reduce the formation of gaps between the closures  214  and  216 , such that the housing  212  generally does not permit fluid to leak from the valve  210 . For example, in certain embodiments, the closures  214  and  216  may be coupled together by more than 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more fasteners  218 . In an alternative embodiment, the closures  214  and  216  are secured to one another by a welded connection, thereby making the housing  212  a one-piece structure. In such an embodiment, the fasteners  218  may be omitted. 
     Each closure  214  and  216  includes multiple openings  220  configured to couple each closure  214  and  216  to a fluid conduit. As will be appreciated, fasteners may pass through the openings  220  and corresponding openings within respective conduits to secure the closures  214  and  216  to the conduits. The number of openings may be selected to substantially reduce the possibility of fluid leakage between the closures  214  and  216  and the conduits. For example, the closures  214  and  216  may include more than 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more openings  220 . 
     As discussed in detail below, the valve  210  includes a ball  230  configured to rotate from an open position to a closed position. The ball  230  includes a bore  232  (e.g., a cylindrical bore) that facilitates the passage of fluid through the valve  210 . In the open position, the bore  232  of the ball  230  is aligned with a bore  228  (e.g., a cylindrical bore) of the closure  214  and a bore  234  (e.g., a cylindrical bore) of the closure  216 , such that fluid may pass through the valve  210 . In the closed positioned, the bore  232  is rotated perpendicular to the closures  214  and  216 , thereby substantially blocking the passage of fluid through the valve  210 . As will be appreciated, rotating the ball  230  to an orientation between the open and closed positions may establish a desired flow rate of fluid through the valve  210  by adjusting the fluid passage area. The ball  230  is rotationally coupled to a stem  222 , such that rotation of the stem  222  causes the ball  230  to rotate. In certain embodiments, the stem  222  is a cylindrical shaft within one or more annular grooves, shoulders, or other features to facilitate sealing and retention in the housing  212 . Furthermore, the stem  222  is coupled to an adapter plate or mounting portion  224  configured to mount with a variety of valve control components. For example, the mounting portion  224  may be mounted to an electric or hydraulic actuator configured to remotely control the position of the ball within the valve  210 . Alternatively, the mounting portion  224  or stem  222  may be coupled to a handle such that the valve  210  may be operated manually. 
     As discussed in detail below, the stem  222  is configured to be removed from the valve  210  without uncoupling the closures  214  and/or  216  from one another. Due to the large number of fasteners  218  that couple the closures  214  and  216  together, the process of separating the closures  214  and  216  may be time-consuming. Consequently, the stem  222  of the present embodiment may be removed from the valve  210  without uncoupling the fasteners  218 . Specifically, the stem  222  may be retained by a removable retainer configured to block inward movement of the stem  222 . Once the retainer has been removed, the stem  222  may pass through the housing  212  from a first side  211  to a second side  213 , thereby completely passing through the housing  212 . As the stem  222  passes through the housing  212  from the first side  211  to the second side  213 , the stem  222  passes through the ball  230  before removal from the valve  210  on the second side  213 . In some embodiments, the stem  222  may be optionally removed through the bore  232  of the ball  230 . In such embodiments, the stem  222  may have a length that is equal to or lesser than the diameter of the bore  232  of the ball  230 , and at least one of the bores  228  or  234 . However, in other embodiments, the stem  222  may have a length that is greater than the diameter of the bore  232  of the ball  230 , thereby helping to guide the stem  222  through the ball  230  when removing the stem  222  from the first side  211  to the second side  213  of the housing  212 . In the illustrated embodiment, the stem  222  is mounted within, and selectively removable from, the closure or body  216  of the housing  212 . However, in other embodiments, the stem  222  is mounted within, and selectively removable from, the closure  214  of the housing  212 , or both the first and second closures  214  and  216  of the housing  212 . Again, once released, the stem  222  is able to pass completely through the housing  212  for removal without separating the first and second closures  214  and  216  and without separating any conduits from the first and second closures  214  and  216 , thereby substantially simplifying the stem  222  removal process to reduce time and costs associated with maintenance operations. 
       FIG. 9  is a cross-section of an exemplary ball valve  210 , taken along line  9 - 9  of  FIG. 8 . As illustrated, the valve  210  is in the closed position, thereby blocking a flow of fluid  226  in an axial direction  27 . In the open position (not shown), the fluid enters the bore  228  of the closure  214 , flows through the bore  232  of the ball  230 , and exits the bore  234  of the closure  216 . In the closed position as shown, the ball  230  is rotated such that the bore  232  is generally crosswise (e.g., perpendicular) to the axial direction  27  through the bores  228  and  234  of the first and second closures  214  and  216 , and thus the sides of the ball  230  block fluid flow through the valve  210 . As previously discussed, the ball  230  may rotate about a radial axis  36  to regulate the flow of fluid  226  through the valve  210 . Rotating the ball  230  varies the flow area between the bore  232  and the closures  214  and  216 , thereby adjusting the flow rate of fluid  226 . To facilitate rotation of the ball  230 , the stem  222  is rotationally coupled to the ball  230  by dowels  238  disposed in recesses  236  of the stem  222  and recesses  240  in an opening  242  of the ball  230 . While two dowels  238  are illustrated in the present embodiment, it should be appreciated that more or fewer dowels  238  may be employed in alternative embodiments. For example, certain embodiments may include 1, 2, 3, 4, 5, 6, 7, 8, or more dowels  238  disposed about the stem  222  (and mounted within recesses  236  and  240 ) in a circumferential direction  39 . In certain embodiments, the stem  222  may be coupled to the ball  230  and housing  212  in the same (or a similar) manner as set forth in  FIGS. 1-7 . In an alternative embodiment, the stem  222  may be rotationally coupled to the ball  230  by a spline connection, a plurality of teeth, a tongue in groove connection, or any combination thereof. 
     In addition to the stem  222 , the ball  230  is coupled to a trunnion  244  on the second side  213  of the housing  212 . The trunnion  244  extends in the radial direction  36  from a trunnion support portion  246  of the housing  212  (e.g., closure  216 ) into an opening  248  in the ball  230 . The trunnion  244  is coupled to the ball  230  by a rotatable joint  250 , which includes a trunnion bearing  252  disposed between the trunnion  244  and the opening  248  in the ball  230 . For example, the trunnion bearing  252  may be an annular bearing, which fits between an annular surface  254  of the trunnion  244  (e.g., cylindrical shaft) and an annular surface  256  of the opening  248  (e.g., cylindrical opening). The trunnion bearing  252  reduces friction between the ball  230  and the trunnion  244 , thereby facilitating rotation of the ball  230  relative to the trunnion  244  in response to a rotational force  258  imparted by the stem  222  onto the ball  230  about a rotation axis  260  of the valve  210 . 
     In the illustrated embodiment, the stem  222  is disposed in an opening or bore  262  in the first side  211  of the housing  212  (e.g., closure  216 ), while the trunnion  244  is disposed in an opening or bore  264  in the second side  213  of the housing  212  (e.g., closure  216 ). As discussed in further detail below, the openings or bores  262  and  264  in the housing  212  are aligned with the openings  242  and  248  in the ball  230 , such that the stem  222  can be installed, accessed, removed, and/or replaced through the housing  212  along the rotational axis  260 . For example, the stem  222  may be installed or removed along the rotational axis  260 , which is generally crosswise or transverse (e.g., perpendicular) to a longitudinal axis  266  of a fluid passage  268  through the valve  210 . The fluid passage  268  generally includes the bore  228  of the closure  214 , the bore  232  of the ball  230 , and the bore  234  of the closure  216 . The stem  222  is removable along the rotational axis  260  without disconnecting the first and second closures  214  and  216  and without disconnecting any fluid conduits from the first and second closures  214  and  216 . This simplified arrangement is enabled by the mounting configuration of the stem  222  in the bore  262  through the first side  211  of the housing  212  (e.g., closure  216 ) and the mounting configuration of the trunnion  244  in the bore  264  through the second side  213  of the housing  212  (e.g., closure  216 ). 
     During operation of the valve  210 , the stem  222  is retained such that movement along the radial direction  36  is blocked. Specifically, movement of the stem  222  along an outward radial direction  270  away from the ball  230  is blocked by contact between the stem  222  and the housing  212  (e.g., closure  216 ). In other words, the stem  222  is internally retained by the housing  212 . As will be appreciated, fluid pressure within the ball  230  may exert a force on the stem  222  in the direction  270 . For example, the fluid pressure may be approximately between 0 to 15,000, 0 to 5625, 0 to 3750, 0 to 2000, or about 0 to 290 psi. In certain embodiments, the area of the stem  222  exposed to the fluid within the ball  230  may be approximately between 0.5 to 4, 1 to 3, or about 2 square inches. Therefore, if the pressure within the ball  230  is approximately 24000 psi and the area of the stem  222  is approximately 2 square inches, the fluid may exert a force of approximately 8000 pounds on the stem  222  in the direction  270 . Consequently, the present embodiment may include a thrust bushing and/or bearing  272  and a thrust washer  274  to facilitate rotation of the stem  222  relative to the housing  212  despite the large contact force between the stem  222  and the housing  212 . As discussed in detail below, the thrust bushing  272  and thrust washer  274  may be disposed about the circumference of the stem  222  between a raised portion  276  of the stem  222  and a recessed portion  278  of the housing  212 . 
     Furthermore, the stem  222  is retained along an inward radial direction  280  by a retainer  282  (e.g., c-shaped retainer). The retainer  282  is disposed within a recess  284  (e.g., annular groove) of the stem  222 , and contacts an outer surface of the housing  212  (e.g., closure  216 ), thereby blocking movement of the stem  222  in the inward radial direction  280 . As will be appreciated, other retention configurations, such as snap-type rings or fixed collars, among others, may be employed in alternative configurations. In further embodiments, the stem  222  may be retained by contact between one or more seals  286  (e.g., annular seals) disposed in grooves  288  (e.g., annular grooves) between the stem  222  and housing  212 . For example, the illustrated embodiment includes two seals  286  in respective grooves  288  at an offset from one another. Although the illustrated seals  286  and grooves  288  are disposed within the bore  262  of the housing  212 , other embodiments may position the seals  286  and grooves  288  in the stem  222  and/or the housing  212 . 
     One or more actuators  290  may be coupled to the stem  222  on the first side  211  of the housing  212 . For example, the actuator  290  may include a manual actuator  292  and/or a powered actuator  294 . The manual actuator  292  may include a handle, wheel, tool interface (e.g., wrench interface), or other manually movable structure. The powered actuator  294  may include an electric drive (e.g., an electric motor), a hydraulic drive, a pneumatic drive, or any combination thereof. The actuator  290  may couple to the stem  222  via an actuator coupling or mount  296 , which may be retained by a retention washer  298  and a retention fastener  300  (e.g., bolt). The valve  210  also includes a lock plate or stop plate  302  disposed between the actuator coupling  296  and the mounting portion  224  of the housing  212 . The stop plate  302  covers the retainer  282  disposed within the recess  284  of the stem  222 , thereby blocking radial movement  36  (i.e., in the outward radial direction  270 ) of the stem  222  away from the housing  212  and the ball  230 . In other words, while the retainer  282  is disposed within the recess  284  of the stem  222 , the retainer  282  is sandwiched between the stop plate  302  and the mounting portion  224 , such that the retainer  282  blocks radial movement  36  in both the inward and outward radial directions  270  and  280 . 
     During maintenance operations, the stem  222  may be released from the housing  212  by removing the actuator  290 , removing the stop plate  302 , and then removing the retainer  282  from the recess  284  in the stem  222 . Upon removal of the retainer  282 , a radial abutment  304  between the raised portion  276  and recessed portion  278  blocks movement of the stem  222  in the outward radial direction  270 , while the stem  222  is free to move in the inward radial direction  280 . With this freedom of movement, the stem  222  may be lowered into the ball  230 , e.g., through the opening  242  in the ball  230 . In certain embodiments as discussed above with reference to  FIGS. 1-7 , the stem  222  may be removed through the bore  232  in the ball  230  and one of the bores  228  or  234  in the housing  212 . However, in the illustrated embodiment, the stem  222  may be removed from the second side  213  of the housing  212  after removal of the trunnion  244  and a trunnion plate or retention cover  306 . 
     As illustrated in  FIG. 9 , the cover  306  is configured to selectively retain the trunnion  244  within the bore  264  of the housing  212  (e.g., closure  216 ) and the opening  248  in the ball  230 . The cover  306  may be secured to the housing  212  by a plurality of fasteners  308 , such as threaded fasteners. For example, the fasteners  308  may include bolts that extend through openings  310  in the cover  306 , and then thread into threaded receptacles  312  in the housing  212 . Thus, the cover  306  may be removed from the housing  212  by unthreading the fasteners  212 . The cover  306  also may include one or more seals, such as a seal  314  (e.g., annular seal) disposed in a groove  316  (e.g., annular groove), disposed between the cover  306  and the housing  212 . The seal  314  helps to block fluid leakage from the passage  268 . In the illustrated embodiment, the cover  306  has a plate portion  318  and a plug portion  320 , wherein the plate portion  318  is disposed in a cover recess  322  along the housing  212 , and the plug portion  320  extends into the bore  264  of the housing  212 . The illustrated seal  314  and groove  316  are disposed about the plug portion  320 , although other embodiments may include one or more seals  314  and grooves  316  disposed along the plate portion  318  and/or the plug portion  320 . The cover  306  also includes a pressure release plug  324  (e.g., a bleed plug, valve, or a combination thereof) disposed within a passage  326  through the cover  306 . For example, the plug  324  may be coupled to the passage  326  with mating threads  328  (e.g., first and second mating threads) between the plug  324  and the passage  326 . The trunnion  244  also includes a passage  330  in fluid communication with the passage  326  in the cover  306 . For example, the passage  330  may include first and second passages  332  and  334 , which are oriented crosswise to one another and intersect one another. The illustrated passages  326  and  330  (i.e.,  332  and  334 ) are also in fluid communication with the fluid passage  268  of the valve  210 , e.g., a cavity  336  between the housing  212  and the ball  330 . For example, the cavity  336  may be positioned between the ball  330  and first and second seat assemblies  338  and  340 , wherein each seat assembly  338  and  340  includes a piston  342 , a seal  344  (e.g., annular seal), a spring  346  (e.g., a wave spring), and a seat  348  (e.g., an annular seat  348 ). Each seat assembly  338  and  340  is biased against the ball  330  to facilitate sealing between the ball  330  and the housing  212 . 
     During the removal of the stem  222 , the pressure release plug  324  may be removed to release pressure from the valve  212  prior to removal of the cover  306  and the trunnion  244 . In some embodiments, the plug  324  may include a pressure release valve, which may be opened by rotating the plug  324 . Upon release of the plug  324  (or opening of any valve in the plug  324 ), any residual fluid pressure in the cavity  336  may exit the valve  210  through the passages  330  and  326 . After this pressure release, the cover  306  may be removed from the housing  212  by unthreading the fasteners  308 . With the cover  306  removed, the trunnion  244  may be removed from the bore  264 , thereby unblocking the opening  248  in the ball  230  and the bore  264  in the housing  212 . Once the retainer  282  is removed from the stem  222  as discussed in detail above, the stem  222  may be lowered completely through the ball  230  (e.g., through both openings  242  and  248  in the ball  230 ), and completely through the bore  264  in the second side  213  of the housing  212 . In this manner, the stem  222  may be removed from the housing  212  of the valve  212  without disconnecting the first and second closures  214  and  216  and without disconnecting any conduits coupled to the closures  214  and  216 . 
       FIG. 10  is a partial cross-section of the ball valve  210  of  FIG. 9 , taken within line  10 - 10 , illustrating the stem  222  disposed within the bore  262  in the housing  212  (e.g., closure  216 ). As illustrated, the stem  222  is selectively retained by the retainer  282  (e.g., a C-shaped ring), which is seated within the recess  284  (e.g., annular recess) in the stem  222  and a corresponding recess  350  (e.g., annular recess) in the housing  212 . In this seated position, the retainer  282  spans across the bore  262  supporting the stem  222 , such that the retainer  282  blocks movement of the stem  222  in the inward radial direction  280 . The retainer  282  is also covered by the stop plate  302 , which blocks the retainer  282  and stem  222  from moving in the outward radial direction  270 . In addition to the retainer  282 , the stem  222  is internally retained within the housing  212  of the valve  210  by the radial abutment  304 . As illustrated, the radial abutment  304  includes a first radial abutment  352  along the stem  222  and a second radial abutment  354  along the bore  262 . For example, the first radial abutment  352  may be an annular shoulder or lip, which is formed between the raised portion  276  and a reduced portion  356  of the stem  222 . In certain embodiments, the raised portion  276  is a first cylindrical portion, the reduced portion  356  is a second cylindrical portion, and the first cylindrical portion  276  has a greater diameter than the second cylindrical portion  356 . Similarly, the second radial abutment  354  may be an annular shoulder or lip, which is formed between the recessed portion  278  and a main portion  358  of the bore  262 . In certain embodiments, the recessed portion  278  is a first cylindrical bore portion, the main portion  358  is a second cylindrical bore portion, and the first cylindrical bore portion  278  has a greater diameter than the second cylindrical bore portion  358 . Together, the first and second radial abutments  352  and  354  block movement of the stem  222  in the outward radial direction  270 , even if the retainer  282  is removed from the stem  222 . Once the retainer  282  is removed, then the stem  222  is removed in the inward radial direction  280  as discussed above. 
     In the illustrated embodiment, the stem  222  also includes the seals  286 , the thrust bushing or bearing  272 , and the thrust washer  274  to facilitate rotation of the stem  222  and ball  230  while maintaining a fluid seal between the stem  222  and the housing  212 . For example, the seals  286  may be annular seals made of an elastomer, a metal, a fabric, or any combination thereof. The bearing  272  and washer  274  may be configured to reduce friction despite a load in the outward radial direction  270  caused by fluid pressure inside the valve  210 . 
     Again, the illustrated stem  222  is coupled to the ball  230  via one or more dowels  238 , which fit within recesses  236  in the stem  222  and recesses  240  in the opening  242  in the ball  230 .  FIG. 11  is a perspective view of an embodiment of the stem  222  of  FIGS. 9 and 11 , further illustrating details of the recess  284  for the retainer  282 , the first axial abutment  352 , and the recesses  236  for the dowels  238 . In the illustrated embodiment, the recess  284  for the retainer  282  is an annular recess extending circumferentially about the reduced portion  356  of the stem  222 . Again, the retainer  282  may be a C-shaped retainer, which fits within the recess  284  to secure the stem  222  to the housing  212 . The first radial abutment  352  includes an annular shoulder or lip  360 , which is formed between the raised portion  276  and the reduced portion  356  of the stem  222 . As illustrated, the portions  276  and  356  are cylindrical portions, which have different diameters to define the lip  360 . Again, the lip  360  helps to internally retain the stem  222  within the housing  212 . The recesses  236  for the dowels  238  are elongated lengthwise along the stem  222 , and are spaced circumferentially about the raised portion  276  of the stem  222 . In the illustrated embodiment, the stem  222  includes four equally spaced recesses  236  for the dowels  238 . Again, the dowels  238  fit within the recesses  236  in the stem  222  and corresponding recesses  240  in the ball  230  to selectively couple the stem  222  to the ball  230 . In other embodiments, the stem  222  may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more recesses  236  for the dowels  238 . 
       FIG. 12  is a perspective view of an embodiment of the ball  230  of  FIGS. 9 and 11 , further illustrating details of the opening  242  for the stem  222  and the opening  248  for the trunnion  244 . In the illustrated embodiment, the opening  242  includes four equally spaced recesses  240  for the dowels  238 , which also fit within the recesses  236  in the stem  222 . Again, the recesses  236  and  240  mate with the dowels  238  to removably couple the stem  222  to the ball  230 . In other embodiments, the opening  242  may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more recesses  240  for the dowels  238 . The ball  230  also includes the bore  232  extending completely through the ball  230 , wherein bore  232  is selectively aligned with the bores  228  and  234  in the housing  212  to permit fluid flow through the valve  210 . The opening  242  is disposed on a first side wall  362  of the ball  230 , and intersects with the bore  232  in the ball  230 . Likewise, the opening  248  is disposed on a second side wall  364  of the ball  230 , and intersects with the bore  232  in the ball  230 . Together, the openings  242  and  248  and the bore  232  define a passage  366  completely through the ball  230  for selectively installing and removing the stem  222 . For example, as illustrated, the passage  366  has an axis  366  disposed along the rotational axis  260  of the valve  210 , wherein the axis  366  is generally crosswise (e.g., perpendicular) to an axis  368  of the bore  232 . 
       FIG. 13  is a cross-section of an exemplary ball valve  210 , illustrating components of the valve  210  exploded from the housing  212  during a servicing operation. In the illustrated embodiment, the pressure release plug  324  (e.g., or pressure release valve) is opened and/or removed to release any internal pressure within the valve  212 , thereby substantially eliminating any force against the stem  222  in the outward radial direction  270 . After this pressure release, the trunnion plate or retention cover  306  is removed by unthreading the fasteners  308  from the housing  212 , thereby enabling removal of the trunnion  244 . The trunnion  244  is then removed through the bore  264  in the second side  213  of the housing  212 . With the cover  306  and trunnion  244  removed from the housing  212 , the openings  242  and  248  in the ball  230  and the bore  264  are open to permit removal of the stem  222 . Accordingly, the retention fastener  300  (e.g., bolt) is removed to enable removal of the retention washer  298  and the manual actuator  292 , thereby further enabling removal of the stop plate  302 . Upon removal of the stop plate  302 , the retainer  282  is removed from the stem  222 , thereby enabling inward radial movement  280  of the stem  222 . At this point, the stem  222  may be removed from the housing  212  by passing the stem  222  through the bore  262  on the first side  211  of the housing  212 , through the opposite openings  242  and  248  in the ball  230 , through the bore  264  on the second side  213  of the housing  212 , and out of the housing  212  of the valve  210 . In this manner, the stem  222  may be removed without disconnecting the first and second closures  214  and  216  and without disconnecting any fluid conduits from the first and second closures  214  and  216 . 
     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.