Clamping the plug end of a control valve

Abstract

A plug assembly configured to secure a plug tip to a valve stem. These configurations may include a clamp that secures to the end of the valve stem. The clamp surrounds at least a portion of the plug tip. In one implementation, the design may also include a spring assembly that creates a preload on the top of the plug tip. The clamp is useful because it accommodates plug tips made from brittle materials such as ceramics. The feature can prevent certain mechanical failures, such as cracking or breakage that may occur during manufacturing or assembly. As an additional benefit, the device can maintain alignment of the plug tip with the valve stem. This feature can ensure proper engagement with a seat in a flow control device such as a control valve.

Description

[Technical field]

[0001] Flow control devices play a major role in many industrial facilities. For example, power plants and industrial processing facilities use different types of flow control devices to manage the flow of materials, typically fluids, throughout a vast network of pipes, tanks, generators, and other equipment. These devices may include control valves that provide active control of the flow through the exchange of control signals with a central control network. In oil and gas facilities, operators may deploy control valves to control the flow of debris-laden fluids that often flow at high temperatures and pressures. These conditions are known to rapidly erode components exposed to the flow. Valve manufacturers may fabricate these components from materials such as ceramics to combat the abrasive effects of the fluids, thus reducing or delaying corrosion or erosion during operation. Summary of the Invention

[0002] The subject matter of this disclosure relates to improvements in valve manufacturing or construction that extend the service life of components in these corrosive environments. Of particular interest are embodiments having mechanisms for fixing components within a control valve (or other flow control device). These embodiments may simplify assembly, for example, by eliminating the need to use high torques to tighten or secure components in place. This feature may ensure better alignment, allow for tolerance stack-up, manufacture components from appropriate materials to avoid thermal expansion mismatches, or slow the rate at which such components may degrade during operation. The underlying advantage, of course, is the reduction in costs to replace or repair equipment in the field. [Brief description of the drawings]

[0003] This specification refers to the following drawings: [Figure 1] FIG. 1 illustrates a schematic diagram of an exemplary embodiment of a plug assembly 100 . [Diagram 2] FIG. 2 shows a perspective view of an example of a construction of the plug assembly 100 of FIG. [Diagram 3] FIG. 3 shows an elevational view of a section of the structure of FIG. 2 in assembled form. [Figure 4] FIG. 4 shows an elevational view of a section of the example structure of FIG. [Diagram 5] FIG. 5 shows a side elevation view of an example of a flow control device construction.

[0004] These drawings and any description herein represent examples that may disclose or describe the invention. These examples include the best mode and enable one of ordinary skill in the art to practice the invention, including making and using any device or system and performing any incorporated method. The drawings are not to scale unless the description indicates otherwise. An element in the examples may appear in one or more of the figures, or in a combination of multiple figures. The figures may use like reference numbers to indicate the same or corresponding elements. The method is merely illustrative and may be modified, for example, by reordering, adding, removing, and / or modifying individual steps or stages. The specification may identify such steps, as well as any parts, components, elements, or functions, in the singular form using the word "a" or "an". However, this should not exclude a plural form of such designation unless the specification expressly states or describes such an exclusion. Reference to "one embodiment" or "one implementation" should not exclude the existence of additional embodiments or implementations that also incorporate the recited features. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] The features of the examples shown in the figures above will now be described. These examples may utilize ceramics because these materials have properties that make them well suited for use in flow control devices for corrosive or erosive fluids. For example, ceramic valve components are particularly robust and provide long service life under conditions (such as high temperatures and pressures) that may prevail in oil and gas applications. However, while they exhibit robust properties, parts made from these materials are inherently brittle and may break during use or manufacture. The designs herein are intended to address the brittleness of these parts. Other embodiments are within the scope of this disclosure.

[0006] 1 shows an example of a plug assembly 100. This embodiment is typically found in a distribution network 102 designed to transport a material 104 throughout a network of conduits 106. The plug assembly 100 may be part of a flow control device 108 having a valve body 110 that connects in series with the conduits 106. The device may also have an actuator 112. A valve stem 114 may extend from the actuator 112 to position the plug assembly 100 in a fixed position adjacent a seat 116. In one implementation, the plug assembly 100 may include a plug tip 118 and a clamp 120.

[0007] In general, the plug assembly 100 may be configured for use in highly aggressive flows. These configurations may include devices that can regulate flows, for example, as part of a valve that regulates fluids in a process. The design of the device may slow wear that may occur due to the characteristics of the flow or the conditions prevailing in the process (such as high temperature or pressure). The design may incorporate materials such as ceramics that have high resistance to corrosion or erosion. As an added benefit, the design may incorporate parts or features that accommodate the physical properties of these materials, including brittleness that may lead to damage or failure of the parts.

[0008] Distribution systems 102 may be configured to deliver or move resources. These configurations may embody vast infrastructures. Materials 104 may include gases, liquids, solids, or even mixtures. Conduits 106 may include pipes or pipelines that are often connected to pumps, boilers, and the like. Pipes may also connect to tanks or reservoirs. In many facilities, this equipment forms a complex network.

[0009] The flow control devices 108 may be configured to regulate the flow of material 104 through the conduits 106 in this complex network. These configurations may include control valves and similar devices. The valve body 110 in such devices is often made of cast or machined metal. This structure may form flanges at the openings I, O. Adjacent pipes 106 may be connected to these flanges. The actuator 112 may use compressed or pressurized air and may generate a load in conjunction with a piston, a spring (or multiple springs), or a flexible diaphragm. The valve stem 114 may form an elongated cylinder or rod that directs this load to regulate the flow of material 104 through the opening in the seat 116.

[0010] The plug tip 118 can be configured to prevent flow through the seat 116. These configurations can include devices that reside within the flow path. These devices can move relative to the seat 116. In one implementation, the devices may comprise a ceramic(s) or have a surface within the flow path made from a ceramic. As noted herein, this feature can provide a long service life, as ceramics and similar materials tend to resist erosion and corrosion consistent with fluid flow, particularly in the hydrocarbon (oil and gas) industry.

[0011] The clamp 120 may be configured to receive the plug tip 118. These configurations may include devices that can secure the plug tip 118 to other portions of the valve, including the valve stem 114. The devices may employ mechanisms that reduce or avoid stresses found in ceramic tips. This feature can avoid damage that may require repair or replacement of the plug tip in the control valve. These mechanisms may also provide superior alignment of the plug tip 118 on the valve stem 114, especially at temperatures as high as 500° C.

[0012] FIG. 2 shows a perspective view of an example of a structure for the plug assembly 100 of FIG. 1 in exploded form. This example includes a load assembly 122 capable of generating a preload. The load assembly 122 may use a spring 124 for this purpose. A constant force spring, a conical spring, or a disc spring such as a Belleville washer may provide sufficient force in a suitably sized package for use in this device. A load bearing member 126 may be inserted between the spring 124 and the top of the plug tip 118. This portion may include one or more plain or flat washers, preferably made of steel or stainless steel, to reduce bearing stresses. The washer 126 may be at the top of the plug tip 118, and is shown here as having a generally cylindrical plug body 128 with an upper shoulder 130 having an outer surface 132 with a tapered portion 134. The plug body 128 may have a diameter that decreases from the tapered portion 134 toward the plug portion 136. The diameter may also preferably vary within the plug portion 136 such that the plug portion 136 provides a geometry on its outer surface 138 for mating and sealing with the sheet 116 (FIG. 1).

[0013] The plug assembly 100 may also include components that secure the plug body 128 to the valve stem 114 (FIG. 1). These components may include a stem adapter 140 with a boss 142 having a diameter that receives the spring 124. The boss 142 may terminate in a shoulder 144 that increases in diameter to form a step 146. The stem adapter 140 may then reduce in diameter to form the boss 148. A hole 150 may extend from the top of the stem adapter 140 into the boss 148. The stem adapter 140 may also include a lateral opening 152 perpendicular to the hole 150. As also shown, the plug assembly 100 may include a pair of clamping members 154, 156. These components may surround the spring 124 and washer 126 and secure the plug body 128 to the stem adapter 140. The clamp members 154, 156 may have a large hole 158 forming a thin peripheral wall 160 with a lateral opening 162. The large hole 158 may terminate in a bottom wall 164. A central opening 166 may extend through the bottom wall 164. The central opening 166 on the "lower" clamp member 156 may include a tapered portion 168, and the peripheral wall 160 may include a stepped portion 170.

[0014] 3 is an elevational view of a cross section of the structure of FIG. 2 in an assembled state. A central opening 166 on the "top" clamp member 154 can be inserted onto the boss 144 of the stem adaptor 140. The plug body 128 can be inserted into the central opening 166 of the lower clamp member 156. A peripheral wall 160 on the lower clamp member 156 can fit into a large hole 158 on the upper clamp member 154. In one implementation, complementary threads on the peripheral wall 160 allow a technician to screw the clamp members 154, 156 together until, for example, the step portion 170 contacts the step 146 on the shoulder 144 of the stem adaptor 142. This design can employ diameters for the shoulder 144 and large hole 158 on the lower clamp 156 as a close or "slip" fit. This feature can ensure proper alignment of the plug body 128 on the valve stem 114 (FIG. 1). The tapered surfaces 132, 164 form an interface that is also useful for maintaining alignment and controlling tolerance stack-up. This interface forms a "cone line" contact. In one embodiment, the tapered surfaces 132, 164 meet at a cone angle of approximately 35°, which can force the plug body 128 downward into the central opening 166 of the lower clamp member 156 in response to thermal expansion.

[0015] FIG. 4 is an elevational view of a cross section of the example structure of FIG. 3. The valve stem 114 can embody an elongated cylindrical rod 172 having an end 174 that inserts into the hole 150 of the stem adapter 140. The end 174 can include a lateral opening 176. In one implementation, assembly may require a technician to first place the upper clamp 154 ​​onto the stem adapter 140 and then assemble the stem adapter 140 onto the rod 172. A weld 178 can secure the stem adapter 140 onto the rod 172. The weld 178 can completely surround the diameter of the rod 172. However, other configurations of weld material may prevail as well. A first pin 180 can be inserted into the lateral openings 152, 176 to provide a more secure engagement of these parts. The technician can then place the spring 124, washer 126, plug body 128, and lower clamp 156. In one embodiment, the load L may be used to compress the spring 124. A technician may use a press (or similar device or fixture) to generate this load. This feature may eliminate the need for a technician to apply high torque to screw the clamps 154, 156 together, thereby avoiding twisting or relative movement of parts that may lead to misalignment of the plug body 128 and the axis of the rod 172. A second pin 182 may similarly reside within the lateral opening 152 on the clamp members 154, 156. The second pin 182 may extend into the stem adapter 140, for example, to prevent separation or accidental removal of the clamp members 154, 156 by a technician.

[0016] 5 is an elevational view of an example of the structure of the flow control device 108 of FIG. 1. The example includes a valve body 110 made from a casting or forging 184. In one implementation, the casting 184 can have one or more parts including a flange 186 and a body 188 that are secured together with fasteners F1. The elongated rod 172 can extend out from the body 188. A fill flange 190 may be secured to the top 186 using, for example, fasteners F2. The fill flange 188 can maintain the position of a particular fill material inside the body 186. The fill material can prevent leakage or fugitive emissions that may occur around the elongated rod 172.

[0017] The following examples include specific elements or clauses to describe embodiments contemplated within the scope of this specification. These elements may also be combined with other elements and clauses to describe embodiments. The scope includes and is contemplated by those skilled in the art for other examples. Such other examples are within the scope of the claims, for example, if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that differ little from the literal language of the claims.

Claims

1. A valve, A valve stem; a plug assembly coupled to the valve stem, the plug assembly comprising a plug tip and a clamp, the clamp having a stem adapter coupled to the valve stem and upper and lower clamps capturing at least a portion of the plug tip.

2. The valve of claim 1 further comprising a spring assembly disposed intermediate said upper clamp and said lower clamp.

3. The valve of claim 1 further comprising a spring assembly disposed between the stem adapter and the plug tip.

4. 2. The valve of claim 1, further comprising a pair of conical springs disposed between said stem adapter and said plug tip.

5. The valve of claim 1 further comprising a pin extending through said upper clamp and said lower clamp.

6. The valve of claim 1 further comprising a pin extending through the upper clamp and into the stem adapter.

7. 10. The valve of claim 1, wherein the upper clamp and the lower clamp engage each other at peripheral walls having corresponding threads.

8. The valve of claim 1 , wherein the stem adapter and the lower clamp contact each other.

9. 2. The valve of claim 1, wherein the lower clamp and the plug tip contact each other on a tapered surface.

10. The valve of claim 1 further comprising a weld about the valve stem.

11. A flow control device, comprising: Ceramic plug tip, A stem adapter; A spring assembly; a pair of clamp members having overlapping peripheral walls, each clamp member having an opening; The flow control device, wherein the opening of one of the pair of clamp members receives the stem adapter and the opening of one of the pair of clamp members receives the ceramic plug tip.

12. The flow control device of claim 11 further comprising a pin extending through each of the pair of clamp members.

13. The flow control device of claim 11 further comprising a pin extending through each of the pair of clamp members.

14. The flow control device of claim 11 , wherein the peripheral wall includes complementary threads to the overlapping portion.

15. 12. The flow control device of claim 11, wherein the ceramic plug tip and one of the clamping members contact each other and have an inclined surface.

16. The flow control device of claim 11 , wherein the spring assembly is disposed between the stem adapter and the ceramic plug tip.

17. The flow control device of claim 11 , wherein the spring assembly creates a preload on the ceramic plug tip.

18. The flow control device of claim 11 further comprising a flat washer disposed between the spring assembly and the ceramic plug tip.

19. The flow control device of claim 11 , further comprising an elongated rod having an end that fits into a hole on the stem adapter.

20. an elongated rod having an end that fits into a hole on the stem adapter; The flow control device of claim 11 , further comprising a pin extending through the stem adapter and the elongated rod.

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