Control valve including a trim having relative movement between a bonnet and a cage

Abstract

A control valve includes a valve trim with relative movement between a bonnet and a cage. The control valve includes a valve body having an inlet, an outlet, and a flow passage connecting the inlet and the outlet. The control valve includes a cage disposed in the flow passage. The control valve includes a control element disposed in the flow passage and movable between a first position and a second position. The control valve includes a bonnet securable to the valve body and disposed adjacent to the cage. The bonnet is adapted to receive a portion of the cage. The control valve includes a coupling formed between the bonnet and the cage, the coupling allowing movement between the bonnet and the cage.

Description

Technical Field

[0001] The present invention relates generally to control valves and, more particularly, to control valves including a valve trim having relative movement between a bonnet and a cage. Background Art

[0002] Known control valves include numerous trim components that are individually positioned within the valve body when the control valve is assembled. Consequently, tolerance stack-ups must be considered when manufacturing and positioning the trim components within the valve body. Furthermore, proper alignment of the trim components is required to ensure that the valve plug properly seats against the seat ring to shut off fluid flow through the control valve. Summary of the Invention

[0003] According to a first example, a control valve includes a valve body having an inlet, an outlet, and a flow passage connecting the inlet and the outlet. The control valve includes a cage disposed in the flow passage and including an external groove. The control valve includes a control element disposed in the flow passage and movable between a first position and a second position. The control valve includes a bonnet securable to the valve body and disposed adjacent to the cage. The bonnet includes an internal groove and has a portion that engages with a portion of the cage. When the portion of the bonnet engages with the portion of the cage, the external groove of the cage and the internal groove of the bonnet are positioned adjacent to each other. The control valve includes a compressible ring disposed within the internal and external grooves to form a coupling portion between the bonnet and the cage. The coupling portion permits movement between the bonnet and the cage.

[0004] According to a second example, a valve trim subassembly for use with a valve body includes an inlet, an outlet, and a flow passage connecting the inlet and the outlet. The valve trim subassembly includes a cage that is positionable in the flow passage and includes an external groove. The valve trim subassembly includes a bonnet that is securable to the valve body and positioned adjacent to the bonnet. The bonnet includes an internal groove and has a portion that engages with a portion of the bonnet. When the portion of the bonnet engages with the portion of the bonnet, the external groove of the bonnet and the internal groove of the bonnet are positioned adjacent to each other. The valve trim subassembly includes a compressible ring disposed within the internal groove and the external groove to form a coupling portion between the bonnet and the bonnet. The coupling portion allows movement between the bonnet and the bonnet.

[0005] According to a third example, a control valve includes a valve body having an inlet, an outlet, and a flow passage connecting the inlet and the outlet. The control valve includes a cage disposed in the flow passage and a control element movable between a first position and a second position. The control valve includes a bonnet securable to the valve body and disposed adjacent to the cage. The bonnet is adapted to receive a portion of the cage. The control valve includes a coupling portion formed between the bonnet and the cage, the coupling portion allowing movement between the bonnet and the cage.

[0006] According to a fourth example, a method of manufacturing a valve trim subassembly for use with a valve body includes providing a cage including an external groove; positioning a compressible ring within the external groove; providing a bonnet including an internal groove; engaging a portion of the bonnet with a portion of the cage; positioning the compressible ring within the internal groove of the bonnet to form a coupling between the cage and the bonnet. The coupling allows movement between the cage and the bonnet.

[0007] Further according to the foregoing first, second, third and / or fourth examples, the apparatus and / or method may further include any one or more of the following:

[0008] According to one example, the portion of the cage includes an outwardly facing step. The outwardly facing step is disposed adjacent to the valve cover.

[0009] According to another example, the step forms a space.The portion of the valve cover includes an inner groove and is disposed in the space formed by the step.

[0010] According to another example, a sealing member is further included. The sealing member is positioned on the surface of the step and is arranged to be compressed between the bonnet and the surface of the step of the cage.

[0011] According to another example, the height of the outer groove is smaller than the height of the inner groove.The compressible ring is disposed in the outer groove and is movable in the inner groove to provide the coupling portion.

[0012] According to another example, the seal is a spiral wound gasket.

[0013] According to another example, the height of the outer groove is greater than the height of the inner groove.The compressible ring is disposed in the inner groove and is movable in the outer groove to provide the coupling portion.

[0014] According to another example, the portion of the cage includes an outwardly facing tapered surface.The compressible ring is sized to cooperate with the outwardly facing tapered surface to expand the compressible ring when the compressible ring is positioned within the outer groove.

[0015] According to another example, the portion of the valve cover includes an inwardly facing tapered surface.The compressible ring is sized to cooperate with the inwardly facing tapered surface to compress the compressible ring when the compressible ring is positioned within the inner groove.

[0016] According to another example, the inner groove of the valve cover comprises a second inwardly facing tapered surface. The second inwardly facing tapered surface is arranged to compress the compressible ring when the compressible ring is removed from the inner groove.

[0017] According to another example, a valve plug guide is further included. The valve plug guide is carried by the cage and is adapted to guide movement of the control element.

[0018] According to another example, the cage includes an internal groove and an internal step. The internal step engages the valve plug guide. The control valve further includes a second fastener disposed within the internal groove of the cage. The second fastener engages a surface of the valve plug guide to couple the valve plug guide to the cage.

[0019] According to another example, a control element is disposed in the cage.

[0020] According to another example, the portion of the valve cover includes an inner groove and is disposed within a space formed by the step.

[0021] According to another example, the valve cage further includes a control element and a valve plug guide, wherein the valve plug guide is carried by the cage and is adapted to guide movement of the control element.

[0022] According to another example, the bonnet includes an inner groove, and the cage includes an outer groove. A compressible ring is further included, the compressible ring being disposed within the inner groove and the outer groove to form a coupling portion.

[0023] According to another example, the portion of the cage includes an outwardly facing tapered surface, and positioning the compressible ring within the outer groove includes engaging the compressible ring against the outwardly facing tapered surface to allow the compressible ring to mate with the outwardly facing tapered surface, thereby expanding the compressible ring.

[0024] According to another example, the portion of the valve cover includes an inwardly facing tapered surface, and positioning the compressible ring within the internal groove of the valve cover includes engaging the compressible ring against the inwardly facing tapered surface to allow the compressible ring to mate with the inwardly facing tapered surface when the compressible ring is positioned within the internal groove, thereby compressing the compressible ring.

[0025] According to another example, further comprising providing a control element and a valve plug guide adapted to guide movement of the control element. The method includes positioning the control element within the cage and coupling the valve plug guide to the cage.

[0026] According to another example, the cage includes an internal groove and an internal step, further comprising: providing a second fastener and engaging with the valve plug guide and the internal step, and disposing the second fastener within the internal groove. The fastener engages a surface of the valve plug guide to couple the valve plug guide to the cage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a cross-sectional view of a control valve assembled according to the teachings of a first disclosed example of the present invention, the control valve including a valve body having an inlet, an outlet, and a flow passage connecting the inlet and the outlet, a valve trim subassembly having a cage, and a coupling portion disposed between the cage and the bonnet to allow movement therebetween.

[0028] Figure 2 is an enlarged partial cross-sectional view illustrating aspects of the cage, portions of the bonnet, and the coupling between the cage and the bonnet.

[0029] Figure 3 and Figure 2 A further enlarged fragmentary view is similar but illustrating aspects of the coupling between the cage and the bonnet.

[0030] Figure 4 is a cross-sectional view of a control valve assembled according to the teachings of a second disclosed example of the present invention, the control valve including a valve body having an inlet, an outlet, and a flow passage connecting the inlet and the outlet, and a valve trim subassembly having a valve plug guide.

[0031] Figure 5 is an enlarged partial cross-sectional view illustrating aspects of the cage, portions of the bonnet, and the coupling between the cage and the valve plug guide.

[0032] Figure 6 is an enlarged partial cross-sectional view illustrating aspects of a cage, portions of a bonnet, and an alternative coupling between the cage and the valve plug guide. DETAILED DESCRIPTION

[0033] Although detailed descriptions of exemplary methods, apparatus, and / or articles are disclosed below, it should be understood that the legal scope of the property rights is defined by the terms of the claims set forth in this patent. Therefore, the following detailed description should be construed as examples only and does not describe every possible example, as describing every possible example would be impractical, if not impossible. Numerous alternative examples may be implemented using current technology or technology developed after the filing date of this patent. It is anticipated that such alternative examples will still fall within the scope of the claims.

[0034] Referring now to the accompanying drawings, Figure 1 A control valve 100 according to the teachings of a first disclosed example of the present invention is illustrated. The control valve 100 includes a valve body 102 having an inlet 104, an outlet 106, and a flow passage 108 connecting the inlet 104 and the outlet 106. The control valve 100 includes a cage 110 disposed in the flow passage 108.

[0035] The cage 110 includes an external groove 112 (at Figure 2 ). The outer groove 112 has a square cross-section that can form an interference fit with the compressible ring 125, as discussed in more detail below. Alternatively, the outer groove 112 can have another cross-section (e.g., rectangular). In the example shown, the cage 110 also includes an integral valve seat 113.

[0036] A control element 114 is disposed in the flow passage 108 and is movable between a first position and a second position. The first position may be associated with the control element 114 being spaced apart from the valve seat 113, thereby allowing fluid flow through the flow passage 108. The second position may be associated with the control element 114 engaging the valve seat 113, thereby preventing fluid flow through the flow passage 108. In the example shown, the control element 114 is a pressure balanced valve plug. However, alternatively and as Figure 4 and Figure 5 As shown, the control element 114 may be an unbalanced valve plug.

[0037] like Figure 1 As shown, a bonnet 116 may be secured to the valve body 102 and positioned adjacent the cage 110. The bonnet 116 includes an internal recess 118 ( Figure 2 ). The inner groove 118 has a rectangular cross-section. However, other cross-sections (e.g., a semi-circular groove) may be used instead.

[0038] When the bonnet 116 receives the cage 110 as shown, a portion 120 of the bonnet 116 engages a portion 122 of the cage 110, and the outer recess 112 of the cage 110 is positioned adjacent the inner recess 118 of the bonnet 116. The portion 120 of the bonnet 116 is shown as a stepped annular protrusion that matingly engages a corresponding structure of the valve body 102. The portion 122 of the cage 110 is shown as an annular protrusion. Positioning the recesses 112, 118 adjacent to one another may include positioning the recesses 112, 118 facing one another, radially aligned, and / or at least partially overlapping. For example, positioning the recesses 112, 118 adjacent one another may include positioning the outer recess 112 adjacent to the ends 124, 126 of the inner recess 118 (at Figure 2 The compressible ring 125 is best seen between the ends 124, 126), thereby allowing the compressible ring 125 to extend between the grooves 112, 118 as shown.

[0039] Compressible ring 125 (in Figure 2 A compressible ring 125 (best shown in FIG. 1 ) is disposed within the inner groove 118 and the outer groove 112 to form a coupling 129 between the bonnet 116 and the cage 110. The coupling 129 allows movement between the bonnet 116 and the cage 110. Thus, the compressible ring 125 forms a non-rigid connection between the bonnet 116 and the cage 110. The compressible ring 125 may be a snap ring or another type of fastener.

[0040] Figure 2 Illustrated Figure 1 Detailed view of the control valve 100. In the example shown, the height 127 of the outer groove 112 is less than the height 128 of the inner groove 118. As a result, the compressible ring 125 can be disposed within the outer groove 112 and can move within the inner groove 118. For example, an interference fit can be formed between the compressible ring 125 and the outer groove 112, which secures the compressible ring 125 within the outer groove 112. Alternatively, the height of the inner groove 118 can be less than the height of the outer groove 112 (e.g., see Figure 6 ). In such an example, the compressible ring 125 can be disposed within the inner groove 118 and can move within the outer groove 112. Regardless of the relative heights of the outer groove 112 and the inner groove 118, the ability of the cage 110 and the bonnet 116 to be movably coupled to each other accommodates differences in thermal expansion rates of the valve body 102, the cage 110, and / or the bonnet 116. Furthermore, movably coupling the cage 110 and the bonnet 116 allows the trim subassembly to be relatively easily installed within the valve body 102, reducing alignment issues. The trim subassembly can include two or more of the cage 110, the control element 114, and the bonnet 116.

[0041] like Figure 2As shown, portion 122 of cage 110 has an outwardly facing step 130 disposed adjacent bonnet 116. Step 130 forms a space 132 in which portion 134 of bonnet 116 is positioned. Internal recess 118 is formed in portion 134 of bonnet 116, which is shown as having a substantially rectangular cross-section.

[0042] Seal 136 is positioned on surface 138 of step 130 and is arranged to be compressed between bonnet 116 and surface 138 of step 130. Seal 136 can continue to sealingly engage cage 110 and bonnet 116 when the relative positions of cage 110, bonnet 116, or valve body 102 change. Thus, regardless of the relative positions of cage 110 and bonnet 116, a seal can continue to be provided between cage 110 and bonnet 116 and / or between cage 110, bonnet 116, and valve body 102. In the illustrated example, seal 136 is a spiral wound gasket. However, seal 136 can be any other type of seal. Another seal 139 is positioned between shoulder 140 of bonnet 116 and stepped surface 141 of valve body 102. Seal 139 prevents fluid flow between valve body 102 and bonnet 116. The seal 139 is shown as a shim gasket or a bonnet gasket. However, other types of seals may be used instead.

[0043] Figure 3 Illustrated Figure 1 FIG2 is another detailed view of control valve 100. In the example shown, portion 122 of cage 110 has an outwardly facing tapered surface 142, and portion 143 of bonnet 116 has an inwardly facing tapered surface 144. The angle of one or more of surfaces 142, 144 is approximately 30°. However, the angles of each surface 142, 144 may be any other angle.

[0044] When the compressible ring 125 is positioned within the outer groove 112, the compressible ring 125 is sized to cooperate with the tapered surface 142 to expand the compressible ring 125. Specifically, when the compressible ring 125 is positioned about the cage 110 and the compressible ring 125 engages the tapered surface 142, the compressible ring 125 expands (increases in diameter). When the compressible ring 125, carried by the cage 110, is positioned within the inner groove 118, the compressible ring 125 is sized to cooperate with the tapered surface 144 to compress (decrease in diameter) the compressible ring 125. In the compressed state, the compressible ring 125 and the cage 110 can be further positioned within the bonnet 116 until the compressible ring 125 is radially aligned with the inner groove 118, thereby allowing the compressible ring 125 to move toward the expanded state and be received within the inner groove 118. When the compressible ring 125 is received within the grooves 112 , 118 , the cage 110 and the bonnet 116 are movably coupled together (eg, coupled in a manner that allows movement between the cage 110 and the bonnet 116 ).

[0045] like Figure 3 As shown, the inner groove 118 has a second inwardly facing tapered surface 146. The angle of the tapered surface 146 is about 60 degrees. However, the tapered surface 146 can be formed at any other angle. When the compressible ring 125 is removed from the inner groove 118, the second inwardly facing tapered surface 146 is arranged to compress the compressible ring 125. Specifically, if the valve stem 148 of the control valve 100 is struck with a hammer (at Figure 1 148 is best shown in the drawing, the control element 114 is driven against the valve seat 113, causing the valve seat 113, the cage 110, and the compressible ring 125 within the outer groove 112 to move downward. As the compressible ring 125 moves downward, it engages and is compressed by the tapered surface 146. When the compressible ring 125 is compressed by the tapered surface 146, the compressible ring 125 can be removed from the inner groove 118, and the cage 110 can be decoupled from the bonnet 116.

[0046] Figure 4 Illustrated is a control valve 250 according to the teachings of a second disclosed example of the present invention. Elements of control valve 250 that are the same or similar to control valve 100 are indicated by the same reference numerals increased by 100. For the sake of brevity, the descriptions of many of these elements are simplified or omitted.

[0047] Control valve 250 and Figure 1 The control valve 100 is similar to the control valve 100. However, Figure 1 Compared with the control valve 100, Figure 4Control valve 200 includes a valve plug guide 252 carried by cage 210. Valve plug guide 252 guides movement of a control element 256 relative to valve seat 213. Valve seat 213 is integrally formed with cage 210. To guide movement of control element 256, valve plug guide 252 includes a bore 257 that receives a portion 258 of control element 256. Due to the interaction between portion 258 of control element 256 and bore 257 of valve plug guide 252, control element 256 is guided relative to valve seat 213. Control element 256 is an unbalanced valve plug. However, other types of valve plugs may be used.

[0048] Figure 5 Illustrated Figure 4 A detailed view of the control valve 250 is shown. In the example shown, the cage 210 includes an internal groove 260 and an internal step 262. A fastener 263 is received within the internal groove 260. The fastener 263 may be a compressible ring, such as a snap ring or a retaining ring. The plug guide 252 engages the internal step 262 and is captured between the internal step 262 and the fastener 263, coupling the plug guide 252 to the cage 210. Specifically, the fastener 263 protrudes from the internal groove 260 and engages a surface 264 of the plug guide 252. In the example shown, a portion 266 of the cage 210 includes an outwardly facing tapered surface 268. When the fastener 263 is positioned within the internal groove 260, the tapered surface 268 is configured to compress the fastener 263.

[0049] Figure 6 Illustrated Figure 4 FIG2 is a detailed view of a control valve 250 having an alternative coupling between a cage 210 and a bonnet 216. In contrast to the above example, the height of the inner groove 218 of the bonnet 116 is less than the height of the outer groove 212 of the cage 210. Thus, the compression ring 225 is disposed within the inner groove 218 and is movable within the outer groove 212. Additionally, the outer groove 212 includes a tapered surface 246. For example, the tapered surface 246 is positioned so that when the valve stem 148 of the control valve 100 is struck with a hammer (at Figure 1 148 is best shown in FIG. 14A ) to allow the compressible ring 225 to be compressed when the compression ring 225 is removed from the outer groove 212 .

[0050] Based on the foregoing, it will be appreciated that the apparatus, methods, and articles disclosed above enable the manufacture of control valves having smaller tolerance variations, thereby reducing the likelihood of leakage. Specifically, using the teachings of the present disclosure, tolerance variations are reduced by forming a valve cage having an integral valve seat and coupling the valve cage to the valve cover using a retaining ring. The coupling between the valve cover and the valve cage substantially ensures relative alignment between the valve cage and the valve cover, and forms a modular valve trim subassembly (valve trim valve core). Due to the non-rigid coupling between the valve cage and the valve cover, thermal expansion between the various components of the control valve is allowed, and the machining tolerance variations between the various control valve components can be increased. In addition, due to the teachings of the present disclosure, the number of parts included in the valve trim subassembly is reduced and the time required to assemble such a valve is reduced, given that no subsequent operations are required to achieve proper alignment and sealing. The modular valve trim subassembly can be formed using additive manufacturing processes, milling processes, etc.

[0051] To assemble one of the trim subassemblies, the valve plug and stem are positioned within the cage, the spiral wound gasket is placed on top of the cage, and the retaining ring is positioned within the groove formed by the outer surface of the cage. If the valve plug is an unbalanced plug, a valve plug guide can be positioned within the cage. To secure the valve plug guide within the cage, it is captured between an internal shoulder of the cage and a fastener carried by the cage. The fastener can be a retaining ring.

[0052] To couple the trim subassembly and the bonnet to form a modular trim subassembly, the end of the cage carrying the snap ring is inserted into the inner diameter of the bonnet until the snap ring is received within a corresponding groove in the bonnet. The interaction between the bonnet, cage, and snap ring forms an interference fit that couples (movably couples) the cage and bonnet together.

[0053] Furthermore, the groove formed by the bonnet is sized (e.g., has a sufficient height) to allow the snap ring and the cage to move up and down during compression or decompression of the spiral wound gasket, while allowing the cage to engage the bonnet during assembly and operation. Specifically, the coupling between the cage and the bonnet formed by the snap ring allows the spiral wound gasket positioned therebetween to expand and contract to fill the gap between the bonnet and the cage, thereby allowing the interface between the bonnet and the cage to remain sealed regardless of the relative position of the cage and the bonnet.

[0054] When the trim subassembly is installed in the valve body, fasteners are received through the bonnet and valve body to couple (e.g., bolt) the valve body and bonnet together and compress the spiral wound gasket and port flat-sheet graphite gasket on top of the cage. This gasket compression allows the cage to engage the bonnet. In contrast, if a rigid connection (such as provided by a threaded connection) is formed between the bonnet and cage, the spiral wound gasket may not be compressed or expand / compress when the bonnet is bolted to the valve body. As a result, an improper seal may be formed and / or components of the control valve may be overstressed.

[0055] In addition, although several examples have been disclosed herein, any features from any example may be combined or replaced with other features from other examples. In addition, although several examples have been disclosed herein, changes may be made to the disclosed examples without departing from the scope of the claims.

Claims

1. A control valve comprising: a valve body, the valve body comprising an inlet, an outlet, and a flow channel connecting the inlet and the outlet; a cage disposed in the flow passage and comprising an external groove; a control element disposed in the flow channel and movable between a first position and a second position; a bonnet securable to the valve body and disposed adjacent the cage, the bonnet including an internal groove and having a portion that engages a portion of the cage, the external groove of the cage and the internal groove of the bonnet being positioned adjacent each other when the portion of the bonnet engages the portion of the cage; as well as a compressible ring disposed within the inner groove and the outer groove to form a coupling between the bonnet and the cage, the coupling permitting movement therebetween, wherein the portion of the cage includes an outwardly facing step disposed adjacent the bonnet, wherein the step forms a space, and wherein the portion of the bonnet includes the interior recess and is disposed within the space formed by the step. 2 . The control valve of claim 1 , further comprising a seal positioned on a surface of the step, the seal arranged to be compressed between the bonnet and the surface of the step of the cage.

3. The control valve according to claim 2, wherein: The outer groove has a height that is smaller than a height of the inner groove, and the compressible ring is disposed within the outer groove and is movable within the inner groove to provide the coupling portion.

4. The control valve according to claim 3, wherein: The seal is a spiral wound gasket.

5. The control valve according to claim 2, wherein: The outer groove has a height greater than that of the inner groove, and the compressible ring is disposed within the inner groove and is movable within the outer groove to provide the coupling portion.

6. The control valve according to claim 1, wherein The portion of the cage includes an outwardly facing tapered surface, and the compressible ring is sized to cooperate with the outwardly facing tapered surface to expand the compressible ring when the compressible ring is positioned within the external groove.

7. The control valve according to claim 6, wherein: The portion of the bonnet includes an inwardly facing tapered surface, and the compressible ring is sized to cooperate with the inwardly facing tapered surface to compress the compressible ring when the compressible ring is positioned within the internal groove.

8. The control valve according to claim 7, wherein: The internal groove of the valve cover includes a second inwardly facing tapered surface arranged to compress the compressible ring when the compressible ring is removed from the internal groove.

9. The control valve according to claim 1, wherein: Also included is a valve plug guide carried by the cage and adapted to guide movement of the control element.

10. The control valve according to claim 9, wherein: The cage includes an internal groove and an internal step, the internal step engaging the valve plug guide, and the control valve further includes a second fastener disposed within the internal groove of the cage, the second fastener engaging a surface of the valve plug guide to couple the valve plug guide to the cage.

11. A valve trim subassembly for use with a valve body, the valve body comprising an inlet, an outlet, and a flow passage connecting the inlet and the outlet, the valve trim subassembly comprising: a cage positionable in the flow passage and comprising an external groove; a bonnet securable to the valve body and disposed adjacent the cage, the bonnet including an internal groove and having a portion that engages a portion of the cage, the external groove of the cage and the internal groove of the bonnet being positioned adjacent each other when the portion of the bonnet engages the portion of the cage; as well as a compressible ring disposed within the inner groove and the outer groove to form a coupling between the bonnet and the cage, the coupling permitting movement therebetween, wherein the portion of the cage includes an outwardly facing step disposed adjacent the bonnet, wherein the step forms a space, and wherein the portion of the bonnet includes the inner groove and is disposed within the space formed by the step.

12. The valve trim subassembly of claim 11, further comprising a control element disposed in the cage.

13. The valve trim subassembly of claim 11, wherein: Also included is a seal positioned on a surface of the step, the seal arranged to be compressed between the bonnet and the surface of the step of the cage.

14. The valve trim subassembly of claim 11, wherein: The outer groove has a height smaller than that of the inner groove. The compressible ring is disposed in the outer groove and is movable in the inner groove to provide the coupling portion between the bonnet and the cage.

15. The valve trim subassembly of claim 11, wherein: The portion of the cage includes an outwardly facing tapered surface, and the compressible ring is sized to cooperate with the outwardly facing tapered surface to expand the compressible ring when the compressible ring is positioned within the external groove.

16. The valve trim subassembly of claim 15, wherein: The portion of the bonnet includes an inwardly facing tapered surface, and the compressible ring is sized to cooperate with the inwardly facing tapered surface to compress the compressible ring when the compressible ring is positioned within the internal groove.

17. The valve trim subassembly of claim 16, wherein: The internal groove of the valve cover includes a second inwardly facing tapered surface arranged to compress the compressible ring when the compressible ring is removed from the internal groove.

18. The valve trim subassembly of claim 11, further comprising a control element and a valve plug guide carried by the cage and adapted to guide movement of the control element.

19. A control valve comprising: a valve body, the valve body comprising an inlet, an outlet, and a flow channel connecting the inlet and the outlet; a valve cage disposed in the flow passage; a control element disposed in the flow channel and movable between a first position and a second position; a bonnet securable to the valve body and disposed adjacent the cage, the bonnet adapted to receive a portion of the cage; as well as a coupling portion formed between the bonnet and the cage, the coupling portion allowing movement between the bonnet and the cage, The bonnet includes an inner radial groove, the cage includes an outer radial groove, and the control valve further includes a compressible ring arranged in the inner radial groove and the outer radial groove to form the coupling portion between the bonnet and the cage.

20. A method of manufacturing a valve trim subassembly for use with a valve body, the method comprising: providing a cage including an external radial groove; positioning a compressible ring within the outer radial groove; providing a valve cover including an internal radial groove; engaging a portion of the bonnet with a portion of the cage; as well as The compressible ring is positioned within the inner radial groove of the bonnet to form a coupling between the cage and the bonnet that allows movement therebetween.

21. The method according to claim 20, wherein The portion of the cage includes an outwardly facing tapered surface, and wherein positioning the compressible ring within the outer radial groove includes engaging the compressible ring against the outwardly facing tapered surface to allow the compressible ring to mate with the outwardly facing tapered surface, thereby expanding the compressible ring.

22. The method according to claim 21, wherein The portion of the valve cover includes an inwardly facing tapered surface, and wherein positioning the compressible ring within the inner radial groove of the valve cover includes engaging the compressible ring against the inwardly facing tapered surface to allow the compressible ring to mate with the inwardly facing tapered surface, thereby compressing the compressible ring.

23. The method of claim 21, further comprising: A control element and a valve plug guide adapted to guide movement of the control element are provided, and the control element is disposed within the cage and the valve plug guide is coupled to the cage.

24. The method according to claim 23, wherein The cage includes an inner radial groove and an inner step, the method further comprising providing a second fastener and engaging the valve plug guide and the inner step, and disposing the second fastener within the inner radial groove, the fastener engaging a surface of the valve plug guide to couple the valve plug guide to the cage.

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