Patent Application
20120241033
This patent relates generally to fluid regulators and, more particularly, to bonnet apparatus for use with fluid regulators.
Fluid regulators are commonly distributed throughout process control systems to control the pressures of various fluids (e.g., liquids, gasses, etc.). Fluid regulators are typically used to regulate the pressure of a fluid to a substantially lower or constant value. Specifically, a fluid regulator has an inlet that typically receives a supply fluid at a relatively high pressure and provides a relatively lower and substantially constant pressure at an outlet. A fluid regulator typically includes a body defined by a bonnet coupled to a valve body.
Safety ratings of fluid regulators are often based on a maximum inlet pressure at which the fluid regulator can safely operate. For example, safety ratings of many fluid regulators are typically based on safety guidelines provided by the Compressible Gas Association, Inc. To comply with certain safety requirements, a bonnet of the fluid regulator is often composed of a relatively high strength metallic material (e.g., zinc, brass, etc.) that can withstand relatively high pressures and/or large temperature ranges. In particular, a bonnet must often be capable of containing potentially broken internal components that may be produced during a failure condition of the fluid regulator. However, a strength (e.g., a yield strength, an impact toughness) of a metallic material such as, for example, a zinc material or alloy (e.g., ZAMAK) of the bonnet or fluid regulator may be affected when the fluid regulator is used in relatively low temperature applications (e.g., −40° C.). For example, a metallic material may be more brittle in colder temperature applications. As a result, the fluid regulator may not be suitable for use in relatively low temperature applications because the fluid regulator may not comply with certain safety guidelines when used in these applications.
In one example, a bonnet apparatus includes a body having a cavity to receive a loading assembly of the fluid regulator. A support structure is disposed in the cavity and extends across the cavity to increase an impact toughness or strength of the body.
In another example, a bonnet apparatus includes a bonnet having a body to define a cavity where the body of the bonnet defines a stepped body portion adjacent an opening of the cavity. A relief is formed in an inner surface of the cavity adjacent the stepped body portion.
In another example, a fluid regulator includes a bonnet having a flange, a boss and a body joining the flange and the boss to define a cavity to receive a loading assembly. The flange is adjacent a first end of the body to couple the bonnet to a valve body of the fluid regulator. The boss is adjacent a second end of the body and has an aperture to receive an adjusting element of the loading assembly. A plurality of support structures is disposed within the cavity adjacent the second end of the body such that the support structures extend outwardly between a hub and an inner surface of the cavity. A relief is formed within the inner surface of the cavity adjacent the first end of the body between the flange and the body.
Example bonnet apparatus described herein significantly improve a safety rating of a fluid regulator. Improving a safety rating of a fluid regulator enables use of the fluid regulator in a wider range of operating conditions than, for example, conventional fluid regulators. For example, a fluid regulator described herein may be used with process fluids having temperatures of approximately −40° C. when the fluid regulator is pressurized to a maximum inlet pressure rating. In contrast, conventional fluid regulators may be used in applications having process fluids at room temperatures (e.g., 25° C.) when the fluid regulator is pressurized to a maximum inlet pressure rating. Additionally or alternatively, the example bonnet apparatus described herein increase a maximum inlet pressure rating of the fluid regulator. Further, example fluid regulators described herein comply with certain safety rating or safety guidelines provided by, for example, the Compressive Gas Association, Inc., when used in relatively low temperature applications (e.g., below 0° C. to −40° C.).
An example bonnet apparatus described herein improves a strength (e.g, a yield strength, impact strength, tensile strength, etc.) of the fluid regulator to increase a maximum inlet pressure rating of the fluid regulator and/or expand the operating temperature range of the fluid regulator. To improve the strength of the bonnet, an example bonnet described herein includes a support structure. Unlike conventional bonnet apparatus, which may fail due to lack of bonnet strength when subjected to process fluids (or ambient conditions) having temperatures of approximately −40° C., the bonnet apparatus described herein have one or more support structures to provide sufficient or increased strength when used in process applications having relatively low temperatures (e.g., process fluids or ambient conditions at temperatures of −40° C.).
More specifically, to increase the strength of the bonnet, the example bonnet apparatus described herein have a support structure or apparatus adjacent a first end of the bonnet. In some examples, the support structure may be disposed in a cavity of the bonnet and comprise webbing having support walls or ribs extending between inner surfaces of the bonnet. For example, the webbing may include one or more support walls or ribs that extend from a central hub or center of the webbing to an inner surface or side wall of the bonnet. In some examples, the webbing extends between opposing inner surfaces of the cavity of the bonnet.
Additionally or alternatively, to increase the strength of the bonnet apparatus, the bonnet apparatus may employ a relief In particular, the relief may be formed in an inner surface of the cavity and positioned adjacent a second end of the bonnet. In particular, the relief is an annular radiused curved surface that more evenly distributes localized stresses along a highly stressed area of the bonnet adjacent a sensing element interface. Further, in some examples, the radiused curved surface is formed via a casting manufacturing process (e.g., “as-cast”) and is not machined. Forming the relief via a casting manufacturing process as opposed to, for example, forming the relief via machining provides a stronger bonnet apparatus because much of the strength in a casting is in the surface or skin of the material and this material is not removed from the bonnet apparatus when forming the relief via casting.
Before discussing an example fluid regulator described herein, a brief description of a known fluid regulator 100 is provided in
A load assembly 116 is disposed within a cavity 118 defined by the body 110 of the bonnet 104 and is adjustable to provide a load to a diaphragm 120, where the load corresponds to a desired fluid outlet pressure. The diaphragm 120 is captured between the bonnet 104 and the valve body 102 to partially define a sensing chamber 122 that is in fluid communication with the outlet 108 via a passageway 124. Further, to provide support to the diaphragm 120, the fluid regulator 100 includes a diaphragm plate 126. The diaphragm plate 126 is typically composed of a high strength material such as, for example, stainless steel. A valve apparatus 128 moves between an open position to regulate or throttle the flow of fluid between the inlet 106 and the outlet 108 and a closed position to restrict fluid flow between the inlet 106 and the outlet 108.
In operation, the load assembly 116 is adjusted to provide a load to the diaphragm 120 that corresponds to a desired outlet pressure. A pressure differential across the diaphragm 120 moves between a closed position to restrict fluid flow between the inlet 106 and the outlet 108 and an open position to allow fluid flow between the inlet 106 and the outlet 108. For example, the valve apparatus 128 moves to a closed position when a fluid pressure at the outlet 108 provides a force to the diaphragm 120 that is greater than or equal to a force provided to the diaphragm 120 by a spring 130 of the load assembly 116. The valve apparatus 128 moves to an open position when the fluid pressure at the outlet 108 provides a force to the diaphragm 120 that is less than a force provided to the diaphragm 120 by the load assembly 116. The pressurized fluid flows between the inlet 106 and the outlet 108 until the forces on opposing sides of the diaphragm 120 are balanced.
A failure condition can occur when the pressure at the outlet 108 significantly exceeds a maximum inlet pressure rating of the fluid regulator 100. For example, a failure condition may occur when the pressure at the outlet 108 is significantly greater than the desired pressure setting provided by the load assembly 116 that may be caused by, for example, improper sealing of the valve apparatus 128, downstream equipment failure, installing the regulator backwards (inlet line pressure to outlet port 108), etc. During a failure condition of the fluid regulator 100, the bonnet 104 has sufficient strength or impact toughness to capture or contain potentially broken internal components (e.g., the spring 130) that may be produced. In particular, the bonnet 104 has sufficient strength to prevent ejection of the load assembly 116 (e.g., the spring 130) from an upper surface or end 132 of the bonnet 104. The diaphragm plate 126, which is composed of a hard metallic material, supports the diaphragm 120 and withstands the forces imparted to the diaphragm 120 by the pressure of the fluid at the outlet 108 in a direction toward the upper surface 132 of the bonnet 104.
However, in some process applications having temperatures of approximately −40° C., the relatively cold temperature of a process fluid or ambient conditions may affect the material properties of the bonnet 104. For example, the material properties of the bonnet 104 may become more brittle causing the bonnet 104 to lose strength or have a relatively less impact toughness when the bonnet 104 is subjected to relatively cold applications or conditions.
The load assembly 220 is operatively coupled to the diaphragm 214 via a diaphragm plate or back-up plate 230 and provides a reference force or load (e.g., a pre-set force) to the diaphragm 214. The diaphragm plate 230 is composed of a material such as, for example, a plastic material (e.g., a rigid plastic material) that is configured to fracture, buckle, shatter or otherwise break during a failure condition of the fluid regulator 200. In other words, the diaphragm plate 230 is composed of a material that is significantly weaker than the material of the bonnet 206. The diaphragm plate 230 is also robust and will not fail during required outlet pressure proof testing and cycle testing.
In this example, the load assembly 220 includes a biasing element 232 (e.g., a spring) disposed within the loading chamber 218 that provides a load to the diaphragm 214 via the diaphragm plate 230. A spring adjuster 234 adjusts (e.g., increases or decreases) the amount of a preset force or load that the biasing element 232 exerts on the first side 216 of the diaphragm 214. As shown, the spring adjustor 234 includes a control knob keyed to a screw 236 that is threadably coupled to the bonnet 206 and engages an adjustable spring seat or spring button 238. The spring button 238 is composed of a ductile, flexible or pliable material such as, for example, an elastomeric material, a plastic material, a ductile metal, etc. to prevent shattering of the spring button 238 during a failure condition and provide an impact cushion for the biasing element 232 during a failure condition. Rotation of the control knob in a first direction (e.g., a clockwise direction) or a second direction (e.g., a counterclockwise direction) varies the amount of compression of the biasing element 232 (e.g., compresses or decompresses the biasing element 232) and, thus, the amount of load exerted on the first side 216 of the diaphragm 214.
A valve apparatus or valve cartridge assembly 240 is disposed within a bore 242 of the valve body 208 that defines an inlet chamber 244 fluidly coupled to the inlet 210. The valve apparatus 240 includes a poppet 246 that moves toward a valve seat 248 to restrict fluid flow between the inlet 210 and the outlet 212 when the fluid regulator 200 is in the closed position. The poppet 246 moves away from the valve seat 248 to allow fluid flow between the inlet 210 and the outlet 212 when the fluid regulator 200 is in the open position. A biasing element 250 biases the poppet 246 toward the valve seat 248. A seal 252 (e.g., an O-ring) is disposed between the valve apparatus 240 and the valve body 208 of the fluid regulator 200 to provide a seal between the sensing chamber 226 and the inlet chamber 244.
In operation, the example fluid regulator 200 fluidly couples to, for example, an upstream pressure source providing a relatively high pressure fluid (e.g., a gas) via the inlet 210 and fluidly couples to, for example, a low pressure downstream device or system via the outlet 212. The fluid regulator 200 regulates the outlet pressure of the fluid flowing through the fluid regulator 200 to a desired pressure corresponding to the preset load provided by the adjustable load assembly 220. In some applications, the process fluid or ambient conditions may have a temperature of approximately −40° C.
To achieve a desired outlet pressure, the spring adjustor 234 is rotated (e.g., in a clockwise or counterclockwise direction) to increase or decrease the load exerted by the biasing element 232 on the first side 216 of the diaphragm 214. The load provided by the biasing element 232 is adjusted to correspond to a desired outlet pressure. With the reference pressure set, the sensing chamber 226 senses a pressure of the pressurized fluid at the outlet 212 via the passage 228, which causes the diaphragm 214 to move in response to pressure changes in the sensing chamber 226.
As the fluid flows between the inlet 210 and the outlet 212, the pressure of the fluid at the outlet 212 increases. As the pressure of the pressurized fluid in the sensing chamber 226 increases, the pressure of the fluid exerts a force on the second side 222 of the diaphragm 214 to cause the diaphragm 214 and the biasing element 232 to move in a rectilinear motion away from the valve body 208. In turn, the biasing element 250 of the valve apparatus 240 causes the poppet 246 to move toward the valve seat 248 to restrict fluid flow between the inlet 210 and the outlet 212. A pressure of the fluid in the sensing chamber 226 that exerts a force on the second side 222 of the diaphragm 214 that is greater than the reference pressure or force exerted by the load assembly 220 on the first side 216 of the diaphragm 214 causes the diaphragm plate 230 to move away from the valve body 208 to allow the poppet 246 to sealingly engage the valve seat 248 to restrict or prevent fluid flow through the fluid regulator 200 as shown in
When the pressure of the pressurized fluid in the sensing chamber 226 is less than the reference pressure or force exerted by the biasing element 232 on the first side 216 of the diaphragm 214, the diaphragm 214 moves, bends or flexes toward the valve body 208. In turn, the diaphragm plate 230 engages a stem portion 254 of the poppet 246 to move the poppet 246 away from the valve seat 248 to allow or increase fluid flow between the inlet 210 and the outlet 212. The poppet 246 moves toward the valve seat 248 to prevent or restrict fluid flow between the inlet 210 and the outlet 212 when the pressure differential across the diaphragm 214 is substantially near zero (i.e., the pressure of the fluid in the sensing chamber 226 is regulated to a pressure that generates a force substantially equal to the load provided by the load assembly 220).
A second end 314 of the body 302 is capped or closed and includes an opening 316 to receive the screw 236 of the load assembly 220. In this example, the opening 316 (e.g., a threaded opening) of the bonnet 206 is defined by a boss 318. The boss 318 of the illustrated example protrudes away from the second end 314 of the body 302. The boss 318 of the illustrated example is integrally formed with the body 302 of the bonnet 206. To vent the loading chamber 218 to, for example, the atmosphere, the second end 314 of the body 302 includes one or more vents 320 radially spaced relative to a longitudinal axis 322 of the cavity 304 and adjacent the boss 318.
To increase an impact toughness and/or strength (e.g., yield strength) of the bonnet 206, the bonnet 206 of the illustrated example includes a support structure 324. The support structure 324 of the illustrated example is disposed within the cavity 304 adjacent the second end 314 of the body 302. In particular, the support structure 324 of the illustrated example includes a plurality of support structures 324 extending across the cavity 304 of the body 302. For example, the plurality of support structures 324 may be radially spaced relative to the longitudinal axis 322 of the cavity 304 at any desired angle (e.g., 90 degrees, 45 degrees, 30 degrees, etc.) such that the support structures 324 do not obstruct or block fluidic communication between the cavity 304 and the vents 320.
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Further, inner surfaces 346 of the respective walls or ribs 328 are spaced relative to each other at an angle 348, and outer surfaces 350 of the walls or ribs 328 are spaced relative to each other at an angle 352. In the illustrated example, the angle 348 between the inner surfaces 346 is approximately 36 degrees and the angle 352 between the outer surfaces 350 is approximately 54 degrees. In other examples, the walls or ribs 328 of the illustrated example may be disproportionately or asymmetrically spaced relative to the longitudinal axis 322. Also, as shown, the webbing 326 of the illustrated example includes eight ribs. However, in other examples, the webbing 326 may include only one wall or rib 328 or any number of walls or ribs 328 to increase the strength or impact toughness of the bonnet 206. For example, the webbing 326 of the illustrated example may include additional ribs disposed between each pair of support structures 342a-342d.
Additionally or alternatively, although not shown, the webbing 326 of the illustrated example may include one or more transverse or interconnecting ribs extending between the outer surfaces 350 and/or the inner surfaces 346 of the respective walls or ribs 328. Such interconnecting ribs may have a relatively straight shape or profile or may have a relatively curved shape or profile. Thus, in some examples, the webbing 326 may have a plurality of ribs or walls extending between the hub 330 and the inner side surface 332 of the body 302 and a plurality of interconnecting ribs extending between surfaces 346 and/or 350 of the ribs or walls 328. In other words, the webbing 326 may form a grid-like support structure.
The support structure 324 (i.e., the webbing 326) of the illustrated example is integrally formed with the bonnet 206 via, for example, casting, machining or any other suitable manufacturing process(es). However, in other examples, the support structure 324 or webbing 326 may be an insert that is coupled (e.g., threadably coupled) to the bonnet 206. For example, the hub 330 may have internal threads and/or outer threads to threadably couple the webbing 326 adjacent the second end 314 of the bonnet 206. In some examples the support structure 324 or webbing 326 may be press-fit (e.g., an interference fit) within the cavity 304 of the bonnet 206.
Further, the support structure 324 is composed of substantially the same material (e.g., zinc) as a material of the body 302 of the bonnet 206. However, in other examples, the support structure 324 may be composed of a different material than the material of the body 302 of the bonnet 206. In yet other examples, a portion of the support structure 324 may be composed of a first material (e.g., stainless steel) and a second portion of the support structure 324 may be composed of a second material. For example, a first support structure portion or first rib may be composed of stainless steel and a second support structure portion or second rib may be composed of zinc or zinc alloy.
The relief 502 of the illustrated example has an arcuate or curved surface 510. For example, the relief 502 has a semi-circular cross-sectional shape or profile. In the illustrated example, the relief 502 is an annular relief about the inner surface 332 of the body 302 adjacent the stepped body portion 308. However, in other examples, the relief 502 may be formed about a partial circumference of the body 302 and/or may be formed intermittently about the circumference of the body 302.
In the illustrated example, the relief 502 is integrally formed with the bonnet 206 via casting. Thus, the relief 502 of the illustrated example is an “as-cast” radius formed in the skin of the bonnet 206. However, in some examples, the relief 502 may be formed via machining or any other suitable manufacturing process(es).
During a failure condition, the diaphragm plate 230 may shatter or collapse, which may cause the diaphragm 214 to fail. More specifically, the diaphragm plate 230 may shatter at a pressure that is significantly greater than an operating pressure, but less than a pressure at which the bonnet 206 will fail. If the diaphragm plate 230 shatters, the pressurized fluid in the sensing chamber 226 vents to the atmosphere via the cavity 304 and the vents 320. Further, the support structure 324 provides increased strength or impact toughness to capture and prevent ejection of internal components (e.g., the spring 232) that may potentially break during the failure condition. In other words, the support structure 324 or webbing 326 prevents the second end 314 of the body 302 from fracturing or breaking off. Additionally, the spring button 238 is composed of a ductile material to provide a cushion to the internal components (e.g., the spring 232) that may eject toward the second end 314 of the body 302 during a failure condition. Further, the relief 502 distributes any localized stresses to prevent the body 302 from fracturing or breaking off at the area 506. In this manner, the support structure 324 and the relief 502 increase the strength and/or the impact toughness of the bonnet 206 to prevent fracture or failure of the bonnet 206 during an overpressure condition.
The bonnet apparatus 206 enables use of the fluid regulator 200 in relatively low temperature applications (e.g., temperatures at or below −40° C.). In particular, the fluid regulator 200 safely vents a rapid increase in pressure within the sensing chamber 226 to the atmosphere during a failure condition while retaining all of the internal components of the fluid regulator 200 within the body 302 of the bonnet 206.
Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
