Packing for high-pressure valves
By using a combined design of PTFE packing ring, anti-extrusion ring and packer bolt in high-pressure valve, the problem of leakage of the high-pressure valve stem is solved, and a sealing effect with low leakage rate at high pressure is achieved, suitable for pressure environments up to 15,000PSI.
Patent Information
- Application Number
- CN202380081417.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-23
- Filing Date
- 2023-11-30
- Publication Date
- 2025-07-04
AI Technical Summary
Existing high-pressure valves are difficult to effectively prevent leakage around the valve stem under high pressure conditions, especially at pressures of 10,000 lbs per square inch or higher, with challenges in packing material and structural design.
The polytetrafluoroethylene (PTFE) filler ring and anti-extrusion ring are used, combined with the packer bolts, and the pressure holding pressure of 100 MPa to 200 MPa is applied in the filler box, and the anti-extrusion ring and metal gasket are formed to form a high sealing structure.
Achieving low leakage rates at pressures up to 15,000 lbs per square inch, significantly improved sealing effect and suitable for high-pressure valve applications.
Smart Images
Figure CN120265907A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to packings for high-pressure valves. Background Art
[0002] In oil and gas processing, valves are often used to direct and regulate the flow of fluids through pipes within a plant. The valve itself includes an outer housing that defines an internal flow passage. Located within the valve is a valve internals that regulates the flow within the flow passage. Some valves include a valve stem that extends from the valve internals through the valve housing into the external environment. The valve stem can be used, for example, to manipulate the valve internals via an operator or actuator. When the valve stem penetrates the valve housing that holds the fluid, a seal or packing surrounds the valve stem to prevent or mitigate leakage along the valve stem from the flow passage to the external environment. Summary of the Invention
[0003] The present disclosure relates to a high-pressure valve having the following features. A valve bonnet defines a stuffing box having an average surface roughness (Ra) of 0.15 or less on the inner surface, for example, Ra between 0.10 and 0.15. In some embodiments, a valve stem extends through the valve bonnet and into the valve body, the valve stem defining an outer surface having an Ra of 0.15 or less. A plurality of polytetrafluoroethylene (PTFE) packing rings are located within a packing stack. A packer is bolted to the valve bonnet and extends into the stuffing box. The packer is configured to apply a holding pressure (i.e., stress) on the packing, for example, between 100 megapascals (MPa) and 200 MPa. Such an arrangement can allow the use of high-pressure valves, for example, valves that can maintain a pressure of 10,000 pounds per square inch (PSI) or 15,000 PSI.
[0004] In some embodiments, the valve may further include an anti-extrusion ring located within the packing stack. In such embodiments, the anti-extrusion ring includes a material harder than PTFE, such as carbon, such as graphite and / or Inconel. Generally, in embodiments having an anti-extrusion ring, the anti-extrusion ring is located at opposite ends of the packing stack.
[0005] In some embodiments, the valve further includes a valve body attached to the valve bonnet, for example, by bolts or similar fasteners. A metal gasket may be located between the valve bonnet and the valve body. In some embodiments, the metal gasket defines a substantially T-shaped profile. In some embodiments, the metal gasket may include a self-tightening metal gasket and / or a compression-lock metal gasket.
[0006] Examples of the subject matter described within the present disclosure are methods having the following features. Provide a valve packing including PTFE packing rings. Insert the provided valve packing into a stuffing box. The stuffing box has an inner surface roughness with an average roughness (Ra) of 0.15 or less, for example, Ra between 0.10 and 0.15. Apply a holding pressure between 100 megapascals (MPa) and 200 MPa to the valve packing via a packer.
[0007] In some embodiments, an anti-extrusion ring can be provided and inserted into a stuffing box having a PTFE packing ring. In such embodiments, the anti-extrusion ring can be disposed on either side of the PTFE packing ring before the valve packing is inserted into the stuffing box.
[0008] In operation, the stuffing box is attached to the valve, and pressure is maintained within the valve by the valve packing. For example, a pressure of 10,000 PSI or 15,000 PSI can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other features will be more readily understood from the following detailed description in conjunction with the accompanying drawings, in which:
[0010] Figure 1 is a side cross-sectional view of an exemplary valve;
[0011] Figure 2 is Figure 1 a side cross-sectional view of the stuffing box of the exemplary valve shown;
[0012] Figure 3 is Figure 1 a side cross-sectional view of the interface between the valve body and the valve bonnet of the exemplary valve shown;
[0013] Figure 4 is a flow chart of an exemplary method that can be used in conjunction with aspects of the present disclosure. DETAILED DESCRIPTION
[0014] Certain embodiments will now be described to provide a thorough understanding of the structure, function, manufacture, and use principles of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the drawings. Those skilled in the art will understand that the devices and methods specifically described and illustrated herein are non-limiting embodiments, and features shown or described in connection with one embodiment can be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.
[0015] In addition, in the present disclosure, similarly named components of embodiments generally have similar characteristics, and thus within a particular embodiment, not every feature of each similarly named component is necessarily elaborated. Further, with respect to the use of linear or circular dimensions in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. Those skilled in the art will recognize that for any geometric shape, equivalent forms of such linear and circular dimensions can be readily determined. The size and shape of the systems and devices and their components can depend at least on the anatomical structure of the object in which the systems and devices will be used, the size and shape of the components in which the systems and devices will be used, and the methods and procedures in which the systems and devices will be used.
[0016] High-pressure valves, for example, valves rated to handle internal pressures of 10,000 pounds per square inch (PSI) or higher, are difficult to manufacture due to limitations in the materials and geometries that can be used under such operating conditions. These difficulties also extend to the selection of packing materials (also known as packing stacks) around the valve stem to prevent or reduce leakage around the valve stem. The present disclosure describes a packing stack and a packing box made of standard materials that can be used together in high-pressure valve applications.
[0017] Figure 1 A cross-sectional view of such a high-pressure valve 100 is shown. In the context of the present disclosure, a high-pressure valve is a valve capable of maintaining a pressure of at least 10,000 pounds per square inch (e.g., 15,000 pounds per square inch). The valve includes a valve body 102 that defines a main flow passage 104 for the working fluid. The valve body can be constructed as a single integral piece, for example, by casting, forging, or additive manufacturing. In some embodiments, the main flow passage 104 can be formed in the valve body by conventional machining. Alternatively or additionally, portions of the valve body 102, such as flanges 106, can be welded, brazed, or otherwise attached to the valve body 102. The upper portion of the valve body 102 defines a cavity that is arranged to receive a valve internals 108 (e.g., a valve plunger or a valve cage). Depending on the type of valve, different valve internals 108 can be used. For example, for a gate valve, a gate and a stem can be received, for a ball valve, a welded ball can be received, for a globe valve, a plunger and a stem can be received, and so on.
[0018] The valve cover 110 is located at the top of the valve body 102. The valve cover 110 defines a central passage 112 for the valve stem 114 to extend from the upper end of the valve cover 110 through the valve cover 110 into the valve internals 108. The valve stem 114 exchanges actuation forces between the valve internals 108 and an external actuator or operator. The upper end of the central passage 112 defines a stuffing box 116. The stuffing box 116 includes a seal 118 to prevent fluid from flowing out of the main flow passage 104 within the valve body 102. More details regarding the seal 118 are provided throughout the present disclosure. In the illustrated embodiment, the valve cover 110 is attached to the valve body by studs 120 and nuts 122. Other attachment mechanisms may be used without departing from the present disclosure, for example, bolts or clamps may be used. In some embodiments, a gasket 124 is included between the valve cover 110 and the valve body.
[0019] Details of the stuffing box 116 are as Figure 2 shown. As discussed previously, the stuffing box 116 itself is defined by the valve cover 110. The inner surface 202 of the stuffing box 116, particularly the surface parallel to the valve stem 114, has an average roughness (Ra) of 0.15 or less, for example, having an Ra of 0.10. In contrast, a typical stuffing box has an Ra of approximately 3.2 (±5%). In some cases, additional machining may be used to achieve such a smooth inner surface 202 after the stuffing box 116 has been formed. Located within the stuffing box 116 is the seal 118 or packing stack 204, which surrounds the valve stem 114 and seals (e.g., partially or completely) the annular space defined by the outer surface of the valve stem 114 and the inner surface 202 of the stuffing box 116.
[0020] The packing stack 204 includes packing rings 205. In some embodiments, the packing rings 205 include polytetrafluoroethylene (PTFE) packing rings 205. While virgin PTFE can be used in the packing rings 205, in some embodiments, PTFE reinforced with carbon (e.g., carbon braid) or other fibers can be used without departing from the present disclosure. In some embodiments, anti-extrusion rings 206 are included within the packing stack 204, and more specifically, at opposite ends of the packing stack 204. These anti-extrusion rings 206 are made of a material harder than the packing rings 205. For example, in some embodiments, the anti-extrusion rings 206 can include carbon and / or Inconel. In some embodiments, the carbon can include graphite. In some embodiments, the total height of the anti-extrusion rings 206 is substantially half (within 10%) of the total height of the packing rings 205. In some embodiments, the total height of the anti-extrusion rings 206 is greater than half of the total height of the packing rings 205. In some embodiments, the height of each anti-extrusion ring is half or greater than the height of a single packing ring 205. In other words, in some embodiments, each anti-extrusion ring 206 is at least half the height of one packing ring 205. In some embodiments, the packing stack defines a reduced control gap to further reduce the leakage rate through the packing stack 204. In some embodiments, the spacing at each control gap 212 is reduced compared to a standard (low pressure) valve. Such gaps 212 are located between the valve stem 114 and the valve bonnet 110, between the guide bushing 214 at the bottom of the packing box 116 and the valve stem 114, between the packer 208 and the valve stem 114, and between the packer 208 and the valve bonnet 110.
[0021] The packer 208 is attached to the upper end of the valve bonnet 110, for example, by bolts or studs 210, and extends partially into the packing box 116 to abut the upper end of the packing stack 204. The packer 208 is configured to apply a hold-down pressure (i.e., stress) on the packing stack 204. This pressure can be adjusted with bolts or studs 210. For example, the desired hold-down pressure can be proportional to the torque of the bolts or nuts on the studs 210. In some embodiments, the hold-down pressure is set between 100 megapascals (MPa) and 200 MPa. In some embodiments, such a load can be applied and / or adjusted when the valve is pressurized with fluid. The packer 208 can be tightened with or without a live load present. It should be noted that the applicant has used such a high hold-down pressure for PTFE packing rings, although the rated hold-down pressure for such PTFE rings is not so. For example, in such an application, the rated hold-down pressure of the PTFE ring is typically on the order of 30 MPa; however, the applicant has tested the arrangements described herein, including the high hold-down pressure, and has found that under both static and dynamic conditions, the leakage through the packing can be less than 1.78×10^-4 millibar liters per second per millimeter of stem diameter. This testing was performed with helium.
[0022] Moving further along the valve, Figure 3 illustrates the interface between the valve body 102 and the valve cover 110. As discussed previously, in some embodiments, the valve cover 110 is attached to the valve body 102 by studs 120. A gasket can be compressed between the valve body 102 and the valve cover 110, for example, by the tension within the studs 120. Various gasket profiles can be used without departing from the present disclosure, for example, Figure 3 the substantially T-shaped profile shown. Such gasket profiles are commonly used in high-pressure applications; however, other self-tightening gaskets can be used without departing from the present disclosure. In some embodiments, the gasket maintains the leakage rate at fifty parts per million or less.
[0023] Figure 4 is a flowchart of an exemplary method 400 that can be used in conjunction with aspects of the present disclosure. At 402, a valve packing 204 including a PTFE packing ring 205 is provided. In some embodiments, an anti-extrusion ring 206 is provided with the PTFE packing ring 205.
[0024] At 404, the provided valve packing ring 205 is inserted into the packing box 116. The packing box 116 can include an inner surface having an average roughness (Ra) of 0.15 or less (e.g., 0.10 Ra). In embodiments where the anti-extrusion ring 206 is also provided, the anti-extrusion ring 206 is also inserted into the packing box 116. For example, the anti-extrusion ring 206 can be placed on either side of the PTFE ring 205 before the valve packing is inserted into the packing box 116.
[0025] At 406, a pressure between 100 MPa and 200 MPa is applied to the valve packing 204 by a packer 208. During operation, the pressure is at least partially retained within the valve by the packing. In some embodiments, the pressure retained within the valve is up to 10,000 PSI. In some embodiments, the pressure retained within the valve is up to 15,000 PSI.
[0026] Although the present disclosure includes many specific implementation details, these should not be construed as limitations on the scope of the claims, but rather as descriptions of features specific to particular embodiments. Certain features described in the context of separate embodiments in the present disclosure can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented separately or in any suitable sub-combination in multiple embodiments. Additionally, although features may have been described above as acting in certain combinations and even initially claimed as such, one or more features from the claimed combination can in some cases be removed from the combination, and the claimed combination can be directed to a sub-combination or a variation of the sub-combination.
[0027] Similarly, although the operations are depicted in the drawings in a particular order, this should not be construed as requiring that such operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to achieve the desired result. Additionally, the separation of various system components in the above-described embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged in multiple products.
[0028] Accordingly, particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require the particular order or sequence shown to achieve the required result.
Claims
1. A high-pressure valve, the high-pressure valve comprising: A valve cover that defines a stuffing box having an average inner surface roughness (Ra) of 0.15 or less; A plurality of polytetrafluoroethylene (PTFE) packing rings located in a packing stack; And A packer bolted to the valve cover and extending into the stuffing box, the packer being configured to apply a holding pressure on the packing, wherein the holding pressure is between 100 megapascals (MPa) and 200 MPa.
2. The high-pressure valve according to claim 1, further comprising an anti-extrusion ring located within the packing stack.
3. The high-pressure valve according to claim 2, wherein the anti-extrusion ring comprises a material harder than PTFE.
4. The high-pressure valve according to claim 2, wherein the anti-extrusion ring is located at opposite ends of the packing stack.
5. The high-pressure valve according to claim 1, further comprising: A valve body attached to the valve cover; A valve stem extending through the valve cover and into the valve body, the valve stem defining an outer surface having an Ra of 0.15 or less; And A metal gasket located between the valve cover and the valve body.
6. The high-pressure valve according to claim 5, wherein the metal gasket comprises a generally T-shaped profile.
7. The high-pressure valve according to claim 5, wherein the valve is configured to hold a pressure of 10,000 pounds per square inch.
8. A high-pressure valve, the high-pressure valve comprising: A valve cover that defines a stuffing box having an average inner surface roughness (Ra) between 0.10 and 0.15; A plurality of polytetrafluoroethylene (PTFE) packing rings located in a packing stack; A packer bolted to the valve cover and extending into the stuffing box, the packer being configured to apply a pressure on the packing; A valve body; A valve stem extending through the valve cover and into the valve body, the valve stem defining an outer surface having an Ra of 0.15 or less; And A metal gasket located between the valve cover and the valve body, wherein the valve is configured to hold a pressure of at least 10,000 pounds per square inch.
9. The high-pressure valve according to claim 8, wherein the holding pressure is between 100 megapascals (MPa) and 200 MPa.
10. The high-pressure valve according to claim 8, further comprising an anti-extrusion ring located within the packing stack.
11. The high-pressure valve according to claim 10, wherein the anti-extrusion ring comprises carbon and Inconel.
12. The high-pressure valve according to claim 10, wherein the anti-extrusion ring is located at opposite ends of the packing stack.
13. The high-pressure valve according to claim 8, wherein the metal gasket comprises a self-tightening gasket or a compression-locking gasket.
14. The high-pressure valve according to claim 8, wherein the valve is configured to hold a pressure of up to 15,000 pounds per square inch.
15. A method, the method comprising: Providing valve packing comprising polytetrafluoroethylene (PTFE) packing rings; Insert the provided valve packing into a packing box having an internal surface roughness with an average roughness (Ra) of 0.15 or less; and Apply between 100 megapascals (MPa) and 200 MPa to the valve packing via a packer.
16. The method according to claim 15, wherein a valve stem extends through the valve, the valve stem defining an outer surface having an Ra of 0.15 or less.
17. The method according to claim 15, wherein the packing box is attached to the valve, the method further comprising: Maintain the pressure within the valve via the valve packing.
18. The method according to claim 17, wherein the pressure is 10,000 PSI.
19. The method according to claim 15, further comprising: Provide an anti-extrusion ring; And Insert the anti-extrusion ring into the packing box.
20. The method according to claim 19, further comprising: Dispose the anti-extrusion ring on either side of the PTFE packing ring before inserting the valve packing into the packing box.