Top-mounted ball valve with pressure-sealed bonnet for power and nuclear applications

Abstract

A compact and lightweight two-piece valve housing (body and pressure-sealed bonnet) design reduces potential leakage paths while providing a top-side ball / stem installation / removal path (when the bonnet is not present). This facilitates initial valve assembly and subsequent inspection / removal of the ball / stem and other internal valve components for maintenance without removing the valve body from its process connection and without removing the support and actuator. The overall length of the sealing seat can be adjusted using fluid, vacuum, thread, or cam to easily assemble the ball within the body. The sealing seat adjustment can be performed with the ball inside or outside the body cavity.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 610,757, filed December 15, 2023; U.S. Provisional Patent Application No. 63 / 612,236, filed December 19, 2023; and U.S. Provisional Patent Application No. 63 / 552,452, filed February 12, 2024. The entire contents of each of these applications are incorporated herein by reference. Technical Field

[0002] This disclosure relates to valves for demanding service applications, and more specifically, to valves for power industry applications, including nuclear applications. Background Technology

[0003] This application relates to a top-mounted ball valve design, which is particularly suitable for use as a main steam isolation valve and feedwater valve in industries such as nuclear power or other power industries. Valves used in nuclear service applications should be constructed to withstand high seismic loads, pressures, and temperatures. The valve should provide high actuator margins and withstand high thrust and torque requirements. The flow can be saturated steam, superheated steam, steam condensate, water, and gas. The main challenges are high-temperature, high-pressure service, thermal cycling due to power plant start-up and shutdown, material selection, fatigue, and wear of sealing surfaces. Some power applications, such as A-USC (Advanced Ultra-Supercritical Power), involve operation at steam temperatures up to 760 degrees Celsius and pressures up to 37.5 MPa.

[0004] Top-mounted valve designs may be well-suited for use in the power industry, particularly the nuclear industry, because they possess several characteristics desired for valves in power industry applications, such as ease of maintenance, seamless connection from the inlet pipe to the outlet pipe, and a high level of reliability, safety, and durability.

[0005] Top-mounted valves have a single, integrated body and a top cover, often referred to as the valve cover. A key advantage of top-mounted valves is that they can be maintained without removing the entire valve from the piping. When removed, the top cover allows direct access to the valve's internal components. This feature is particularly valuable in nuclear applications where minimizing downtime and exposure to hazardous environments is critical. In radioactive environments, maintenance time and radiation exposure time are strictly controlled and must be as short as possible for maintenance operators.

[0006] The one-piece body of a top-mounted valve ensures there are no seals along the waterway. Only the body is attached to the inlet and outlet pipes. Under stress on the inlet or outlet pipes, there is no risk of leakage in the body. This contrasts with valve designs that have seals between two or three components forming the body, which present a risk of leakage at the interfaces when the components are assembled (e.g., during plant startup and when temperature gradients exist in the process lines).

[0007] By eliminating all seals between the components forming the valve body assembly, large mechanical connections to clamp the seals are unnecessary. This results in a monolithic body with optimized wall thickness from the valve inlet pipe to its outlet pipe connection. This helps save space and weight, which are often limiting factors in nuclear facilities. It also helps maintain uniform thermal and mechanical stresses from the inlet pipe connection to the outlet pipe connection, which is crucial for extending the expected life of the valve body and meeting all mechanical safety precautions.

[0008] The robust construction of top-mounted valves ensures reliable sealing and operation under the high pressure and high temperature conditions common in power plants. Because internal components such as the ball, seat, and stem are inserted from the top cover end, there are fewer constraints on dimensions, especially critical dimensions that withstand high operating pressures, torques, and temperatures, compared to side-mounted ball valve designs.

[0009] The ability to perform maintenance without removing valves from process lines reduces the risk of exposure to radioactive materials and other hazards, thereby improving the overall safety of maintenance personnel. Furthermore, top-mounted valves are designed to withstand the harsh conditions of nuclear environments, including exposure to radiation and corrosive substances.

[0010] Ball valves offer several advantages in the power industry, such as better flow resistance, quick opening or closing, a tight seal between the ball and seat, ease of use and technology that increases service life, durability and long lifespan, versatility, and resistance to high pressure and high temperature.

[0011] Ball valves exhibit low flow resistance due to their full-bore design and the absence of geometry in their flow path when fully open. This results in minimal pressure drop and maximum efficiency in power plants.

[0012] Ball valves can be quickly opened and closed by rotating the ball 90 degrees. This rapid operation is crucial in power applications where quick response times are required in emergency situations.

[0013] Reliable airtight seals can be provided in ball valves (including metal-seated ball valves). Most ball valves are designed with a ball in contact with the seat, thus functioning like an autoclave. Essentially, the higher the pressure at the valve inlet, the higher the contact pressure between the sealing surface of the seat and the ball, and the greater the shut-off effect. This is a highly desirable feature in power plants to prevent leakage of high-pressure steam or other fluids.

[0014] Ball valves in power applications such as steam applications use hard materials (e.g., coatings, welds, plating, diffusion) on the ball, seat sealing surfaces, and bearing surfaces (e.g., thrust washers and trunnions) to enhance bearing stress resistance, reduce wear during valve cycle life, and maintain a highly tight shut-off over time.

[0015] When the sphere is fully open, there are no elements in the flow orifice for sealing purposes, so the sealing surfaces are unlikely to wear because they are not in direct contact with the fluid. Additionally, since there are no elements in the flow orifice, there are no disturbances to the flow, such as cavitation that could occur in water supply services or pressure drops that could affect plant efficiency. This minimizes the risk of wear that could affect seal performance over time, such as erosion or steam shearing.

[0016] Demand-response ball valves are versatile and can withstand a wide range of fluids, including liquids, steam, gases, and slurries. This makes them suitable for various applications within power plants, from controlling steam flow to managing cooling water.

[0017] Ball valves can operate effectively under high pressure and high temperature conditions, or when there is a significant temperature gradient between internal components and the ball valve body. This makes them ideal for applications involving high-pressure steam, hot water, thermal shock, and / or rapid cooling.

[0018] For these reasons, choosing top-mounted ball valves for use in power plants (including nuclear power plants) is attractive.

[0019] Figure 1A conventional top-mounted ball valve is shown. The body 101 of the top-mounted ball valve is integral, housing all internal components, including sealing components such as the ball 103 and the seat 104. Seats are arranged on each side of the ball. The bonnet 102 is part of the valve, covering the cavity within the body where the ball and seats are located. The bonnet is typically attached to the valve body using a bolted flange connection (e.g., using studs 113 and nuts 114), with a seal 110 between the body and the bonnet to prevent any leakage. The top-mounted bonnet allows access to the valve's internal components without removing the entire valve from the pipeline. For example, access to the internal components can be obtained by removing the bonnet 102. The height of the bonnet can be adjusted according to the temperature of the process medium. The more extreme the temperature (high or low), the longer the bonnet is to protect the packing rings (111b) and O-rings (111c).

[0020] Seal 110 operates under compression to ensure no leakage between body 101 and cover 102. In top-mounted valves and general valves, body 101, cover 102, and bolted flange connection are designed to generate minimal compressive stress on seal 110 to fill all voids between the surfaces of body 101, seal 110, and cover 102 and ensure no body / cover leakage under low pressure (seating load and stress). Top-mounted valves and general valves are also designed to generate compressive loads on seal, which are several times the internal load (maintenance factor) generated by the valve's internal pressure. The load generated by bolted flange connection is not linearly related to the seal diameter. In addition to being linearly related to the seal diameter to generate gasket seat load, it is also proportional to the square of the seal diameter to counteract hydrostatic end load.

[0021] The ball 103 is the primary component for controlling or isolating flow in top-mounted valves and general ball valves. The ball 103 has a bore through its center, the size of which is similar to the body's inlet and outlet orifices. When the ball 103 is rotated 90 degrees by a valve handle or actuator, it allows or blocks flow through the orifice. The ball can be floating, i.e., held in place solely by the valve seat 104, or supported by trunnion bearings at its top and bottom (e.g., lower trunnion bearing 120b and upper trunnion bearing 120c).

[0022] The valve seat 104 is located on both sides of the ball and provides a tight seal when the valve is closed. Several components, such as the spring retaining ring 104a and the valve seat spring 116a, are used to preload the valve seat 104 against the ball 103, which generates sufficient bearing stress between the ball 103 and the valve seat 104 to provide a tight seal under low pressure.

[0023] On the outer diameter of valve seat 104, there is a normally pressure-self-tightening valve seat gasket 111d (i.e., it requires pressure to seal). By adjusting the outer diameter of valve seat gasket 111d to be larger than the ball-to-seat sealing diameter, the pressure self-tightening effect of the valve seat-to-ball contact can be made positive. This means that the higher the inlet pressure, the higher the preload between the ball and the valve seat, and the higher the sealing pressure at the ball-to-seat contact.

[0024] The valve stem 105 connects the ball to the handle or actuator. It is responsible for transmitting the rotational motion and the required torque to open or close the valve ball 103 to control the flow through the valve. The valve stem is typically sealed with an O-ring or packing ring (111b represents a packing ring and 111c represents an O-ring) to prevent leakage.

[0025] The O-ring 111c and packing ring 111b make the valve stem assembly a pressure-retaining part and cause the valve stem to resemble a piston attempting to leave the valve. The higher the pressure inside the valve or the larger the diameter of the valve stem in contact with the O-ring (111c) and packing ring (111b), the higher the thrust load acting on the valve stem and attempting to push the valve stem out of the valve.

[0026] To prevent the valve stem 105 from leaving the valve, the valve stem 105 is designed with a different diameter along its main axis, with a larger diameter at the bottom. The larger valve stem diameter contacts the valve stem thrust washer 121a and the valve cover 102.

[0027] Thrust washers are designed to support the high bearing loads generated by internal pressure and the resulting stem thrust. These thrust washers also serve as stem guide bushings to ensure that the stem remains concentric with the bonnet and packing ring or O-ring at all times. Lack of concentricity can lead to lateral bearing of the stem (105) and packing ring (111b), premature leakage of the packing ring or O-ring, and potential wear between the bonnet and stem, thereby increasing the overall valve operating torque.

[0028] Standard top-mounted ball valve designs have limitations. For example, the larger the diameter of the valve flow orifice, the larger the spherical surface of the ball. Therefore, the diameter of the top opening of the body 101 and the seal 110 between the body 101 and the bonnet 102 must be increased to allow the ball 103 to be inserted. Since gasket compression depends on its diameter, the body / bonnet load and bolt tightening force required to compress the seal can increase significantly for large ball orifices. For large top-mounted ball valves, such as those required for efficient use in power applications, this necessitates the use of heavy-duty bolts to connect the body and bonnet.

[0029] Figure 2 and Figure 3 An example of a conventional multi-turn valve that can also be used in power and nuclear applications is shown. Figure 2 A pressure-sealed body / bonnet multi-turn valve is shown, and Figure 3A bolted body / bond multi-turn valve is shown. Bolted bond multi-turn valves also suffer from the same problem of increased body / bond connection dimensions. The larger the wedge (303) or parallel sliding disc wedge (203) used to block flow within the valve body (e.g., 201, 301), the larger the required seal between the bolted body and the bond (e.g., 202, 302), and the higher the compressive load required to ensure no leakage occurs between the bolted body (e.g., 201, 301) and the bond. In bolted bond configurations ( Figure 3 In the case of bolted valve cover studs (311b) and nuts (311a), the size or number of bolts connecting the valve cover studs (311b) and nuts (311a) will be larger.

[0030] For large multi-turn valves (e.g., pressure rating 900 or above, size NPS8 and above), one of the trends in the multi-turn valve industry is the shift from bolt-connected bonnet designs ( Figure 3 ) to pressure-sealed valve cover design ( Figure 2 ).

[0031] The pressure-sealed multi-turn valve design is similar to a bolted bonnet valve design, except for the body / bonnet connection and seals. It includes the same internal components, such as wedges (303) or parallel sliding disc wedges (203), to block flow and is operated by a valve stem (205, 305). The pressure-sealed bonnet 202 is floating and freely movable along the valve stem axis, while a pressure-sealing gasket 207 is encapsulated between the bonnet 202, the spacer ring 206, and the gasket retainer 208.

[0032] The pressure-sealed valve cover (e.g., 202) functions by utilizing the internal pressure of the valve to enhance its sealing capability. For example, the pressure-sealed valve cover (e.g., 202) is pressed against the pressure-sealing gasket (e.g., 207) by initially tightening the pressure-sealed valve cover studs and nuts (e.g., studs 211a and nuts 211b). This forms an initial sealing barrier between the pressure-sealing gasket inner diameter (gasket ID) and the valve cover, and between the pressure-sealing gasket outer diameter (gasket OD) and the body, which is sufficient to achieve a seal under low internal pressure.

[0033] As the internal pressure of the fluid in the valve increases, it pushes the valve cover upwards onto the gasket. This pressure strengthens the seal, making it tighter. Essentially, the higher the internal pressure, the tighter the sealing barrier becomes.

[0034] Unlike bolted bonnets that rely solely on the mechanical force of the body / bonnet bolts, pressure-sealed bonnets use a retainer system (e.g., pressure-sealed bonnet retainer 209 and pressure-sealed gasket retainer 208) to maintain and improve the seal. This makes them particularly effective in high-pressure applications, as the seal strength increases with pressure.

[0035] Compared to multi-turn bolted bonnet designs, pressure-sealed designs only require pressure-sealing studs and nuts for initial pre-tightening of the pressure-sealing gasket. This means that the size and number of pressure-sealing studs and nuts can be significantly reduced compared to bolted bonnet joints. Furthermore, pressure-sealing studs and nuts can be evenly distributed across a diameter smaller than the inner diameter of the pressure seal, whereas in bolted bonnet joints, studs (311b) and nuts (311a) are typically evenly distributed across a diameter larger than the joint seal (310). This allows for a more compact and lighter pressure-sealed design than an equivalent bolted bonnet design. Attached Figure Description

[0036] Figure 1 This is an isometric partial sectional view of a conventional top-mounted ball valve.

[0037] Figure 2 It is an isometric partial sectional view of another conventional multi-turn valve structure with a pressure-sealed valve cover and a parallel sliding disc wedge.

[0038] Figure 3 Another conventional multi-turn valve structure with a bolted bonnet and wedge-shaped elements is depicted.

[0039] Figure 4A Conceptually, a top-mounted ball valve with a pressure-sealed bonnet according to some embodiments of the present disclosure is described, which is a combination of a conventional top-body ball valve with a bolted bonnet and a conventional pressure-sealed bonnet multi-turn valve.

[0040] Figure 4B Conceptually, a comparison is drawn between the diameter of a bolted valve cover and a pressure-sealed valve cover, under the same valve flow orifice size and pressure rating, according to some embodiments.

[0041] Figure 5A It is a top-mounted ball valve with a pressure-sealed valve cover according to some embodiments of this disclosure.

[0042] Figure 5B It shows the relationship with Figure 5A The valve shown is similar to the one shown, but with the step reversed.

[0043] Figure 6A It is a top-mounted ball valve with a pressure-sealed bonnet according to some other embodiments of this disclosure.

[0044] Figure 6B It shows the relationship with Figure 6A The valve shown is similar to the one shown, but the valve stem is inverted.

[0045] Figure 7 illustrates an example installation process of the ball in a top-mounted ball valve with a pressure-sealed bonnet according to some embodiments of the present disclosure. Detailed Implementation

[0046] As described above, conventional top-mounted ball valves can be improved to achieve better performance in power applications, such as nuclear applications. The inventors have focused on modifying top-mounted ball valves for optimal use in demanding nuclear power applications. Example embodiments make the top-mounted ball valve more compact and reduce its overall weight. A lighter valve is beneficial to the piping system around the valve because it reduces mechanical stress under normal conditions and in the event of accidents such as earthquakes.

[0047] To construct a top-mounted ball valve that can better serve the high-temperature and high-pressure requirements of power applications (e.g., including nuclear applications), the inventors have constructed a top-mounted ball valve with a pressure-sealed bonnet. The ball valve design with a pressure-sealed bonnet is a unique and innovative solution developed for use in environments such as, but not limited to, small modular reactors (SMRs) and other advanced nuclear reactor applications. This design leverages the inventors' extensive experience in nuclear and demanding service valve solutions, combining features of nuclear valves, such as pressure-sealed valve technology, with a ball and seat assembly for high-temperature and high-pressure demanding service applications.

[0048] Figure 4A Conceptually, this invention illustrates a combination of design concepts from a conventional top-mounted ball valve 402 and a conventional multi-turn pressure-sealed cover 404, according to embodiments of the present disclosure, to construct a top-mounted ball valve incorporating a pressure-sealed cover 406. Figure 4B The illustration shows an example where the joint diameter of a pressure-sealed bonnet valve is relatively smaller when compared to that of a bolted bonnet valve for a multi-turn valve (left) and a top-mounted ball valve (right).

[0049] However, for such Figure 1 The standard top-mounted ball valve design shown, which simply replaces the bolted joint connection and bonnet design with a pressure-sealed gasket and floating bonnet, results in undesirable valve characteristics such as potential leakage, increased operating torque, and accelerated wear of the sealing surfaces. Several challenges have been encountered in developing top-mounted ball valves with pressure-sealed bonnets, according to implementations suitable for nuclear service and other power industry applications.

[0050] Because the floating pressure-sealed bonnet moves freely along the stem axis, and the bonnet uses internal pressure to push the pressure-sealing gasket, one of the challenges in creating a top-mounted ball valve with a pressure-sealed bonnet is that maintaining contact between the stem and the bonnet, which has an internal thrust washer, may be impossible. In scenarios where contact is not maintained, the thrust washer at the bottom of the stem will not function properly. This can lead to premature wear of the stem packing ring or O-ring, resulting in leakage.

[0051] Even in scenarios where the valve stem with an internal thrust washer remains in contact with the valve cover, the valve stem and thrust washer will travel along the valve stem axis in the same manner as the valve cover. This reduces the contact surface between the ball and the stem, and thus reduces the maximum torque that the valve stem can transmit to the ball without damaging either component.

[0052] Because the floating pressure-sealed bonnet moves freely along the stem axis and the bonnet uses internal pressure to push the pressure sealing gasket, the upper trunnion bearing, guided by the bonnet's outer diameter, also moves freely along the stem axis. The contact pressure between the ball's upper trunnion and its mating trunnion bearing is carefully designed to support the internal loads caused by the seat spring preload and the valve medium pressure, thus ensuring minimal wear during ball stroke operation. When the trunnion bearing and the pressure-sealed bonnet move together along the stem axis, the contact surface between the ball's upper trunnion and the mating bearing is reduced. This can cause a significant increase in bearing stress, leading to premature wear during ball stroke, or it can cause the ball trunnion to disengage from the trunnion bearing.

[0053] Other challenges in constructing a top-mounted ball valve with a pressure seal can include the fact that the actuator position is not fixed, especially when the lever or valve actuator is mounted on the bonnet and the floating pressure-sealed bonnet moves freely along the stem axis. This can affect the piping and cables connected to the actuator. Additionally, the lack of stiffness can cause low natural frequency responses in the assembly bonnet, support, and actuator. Under seismic conditions, the low-frequency response of the assembly can be mechanically significant.

[0054] The top-mounted ball valve with pressure-sealed bonnet provided in this disclosure addresses each of the aforementioned design challenges, resulting in a valve that offers improved ease of maintenance, enhanced maneuverability in confined spaces, and improved safety and reliability. It is also more compact and lighter than conventional top-mounted ball valves.

[0055] According to embodiments of this disclosure, the valve is a top-mounted ball valve design with a pressure sealing device between the body and the valve cover. The pressure sealing device and the valve cover may be located between the body and the actuator, or on the body side opposite the actuator. Figure 5A and Figure 6A Two different example embodiments of a top-mounted ball valve with a pressure-sealed bonnet, according to some embodiments of the present disclosure, are shown.

[0056] Figure 5A A top-mounted ball valve with a pressure-sealed valve cover (502) according to an embodiment of the present disclosure is shown. In this configuration, the valve stem (505) is inserted from the top and extends out of the body (501). No valve stem is inserted into the floating valve cover (502).

[0057] This configuration also illustrates a trunnion-mounted ball (518) configuration guided by upper and lower trunnion bearings (512 and 513, respectively). High pressure and larger valve size (e.g., equal to or greater than NPS6) may favor the trunnion-mounted ball configuration because it allows for a significant reduction in the torque required to open the ball (518) against pressure differentials.

[0058] The two valve seats (bidirectional valve seats 520) are symmetrical and preloaded against the ball 518 by a seat spring 521. Behind each valve seat 520, there is a pressure-self-tightening back seat gasket 519, which ensures no leakage between the body 501 and the valve seat 520 and actively increases the preload between the valve seat 520 and the ball 518 when the inlet medium pressure increases. This symmetrical valve seat configuration makes the valve bidirectional.

[0059] Figure 5A The advantage of the configuration described is that it significantly improves valve maintenance. Compared to a standard top-entry ball valve, the valve cover retainer (509) and valve cover (502) can be accessed without removing the support and actuator. The valve cover retainer (509) can be directly accessed. Furthermore, once the valve cover 502 is removed, maintenance personnel can directly access the valve's internal components (ball, seat, trunnion, etc.). This configuration helps reduce the time required for valve maintenance operations, especially in nuclear radiation environments.

[0060] Figure 6A A top-mounted ball valve 600 with a pressure-sealed bonnet according to another embodiment is shown. In this configuration, the valve stem (605) is inserted into and extends out of the floating bonnet (602). There is no additional borehole on the opposite side of the actuator in the body (601) for the valve stem to enter.

[0061] The ball 603 is shown in a floating configuration. This means that the ball is supported only by valve seats (e.g., upstream valve seat 620 and downstream valve seat 624).

[0062] Two distinct valve seats (e.g., upstream seat 620 and downstream seat 624) are provided for unidirectional applications. The inlet seat 620 is floating and preloaded against a ball using a seat spring 621. No backseat gasket is required. The outlet seat 624 can be press-fitted to the body, bolted to the body, welded to the valve body, or integrally formed with the valve body. In the case of a press-fit or bolted seat configuration, a backseat gasket is required to ensure no leakage between the body and the outlet seat. In the case where the seat is welded to the body, the weld deposit between the seat and the body acts as a sealing barrier to prevent leakage behind the seat. In the case where the seat is machined as part of the body (referred to as an integral seat configuration), no gasket is required. The configuration shown includes a backseat gasket 619.

[0063] Figure 6AThe advantage of the configuration described in the text is that it is compatible with... Figure 5A Compared to the configuration shown, it reduces the number of potential leakage paths (e.g., no additional drilling in the body). Furthermore, all maintenance operations (e.g., internal component replacement, packing ring maintenance, pressure seal gasket maintenance, actuator maintenance) are performed only on one side of the valve, and no additional maintenance clearance is required on the valve body side opposite the actuator.

[0064] The pressure sealing device in the example implementation and about Figure 2 The described multi-turn pressure-sealed valve is similar and consists of pressure-sealing gaskets (506, 606) encapsulated between a floating pressure-sealed valve cover (502, 602), spacer rings (507, 607), and a pressure-sealing body (valve body 501, 601). The spacer rings (507, 607) are locked in place by gasket retainers (508, 608).

[0065] To form an initial seal on the valve cover (502, 602) under low internal pressure, the valve cover is pressed against the gasket (506, 606) using studs (511a, 611a) and nuts (511b, 611b) and valve cover retainer plates (509, 609) located on the body (501, 601).

[0066] Fluid passing through valves (500, 600) can be isolated by rotating a ball by a quarter turn (e.g., 90 degrees), which can be floating (603) or trunnion mounted (518).

[0067] In the case of a trunnion-mounted ball, the upper ball trunnion and the lower ball trunnion are guided by the upper trunnion bearing (512) and the lower trunnion bearing (513), respectively.

[0068] This design allows the use of hard materials (coatings, welds, plating, diffusion) on the ball, valve seat sealing surfaces, and trunnion bearing surfaces. Since a large portion of power plant processes operate at temperatures above the limits of polymer materials, the use of soft materials in internal components is generally prohibited.

[0069] Independent of the ball configuration, the seat assembly can be completely symmetrical to achieve bidirectional sealing capability (i.e., identical sealing performance on both sides of the valve), or it can be designed to achieve unidirectional sealing capability, where different seat assemblies are located upstream or downstream of the ball (i.e., the valve is designed to seal only in one preferred direction). Both bidirectional and unidirectional upstream seat assemblies use seat springs (521, 621) for preload. These seat springs provide the initial ball and seat preload and induce bearing stress between the seat sealing surface and the ball to achieve a low-pressure seal. Both bidirectional and unidirectional crimped or bolted downstream seat assemblies use a backseat gasket (519, 619) to ensure no leakage between the body and seat.

[0070] The ball's quarter-turn movement is operated by the valve stem (505, 605). The valve stem (505, 605) can be inserted into the floating pressure-sealed valve cover with its top connection extending beyond the cover, or it can be inserted into the body with its bottom connection extending beyond the body housing, opposite the pressure-sealed valve cover.

[0071] The valve stem (505, 605) is guided by a lower stem guide bushing and an upper stem guide bushing (515 and 514 in valve 500, and 626 and 625 in valve 600) in the bonnet (502, 602) or body (501, 601). These guide bushings are encapsulated in the bonnet or gland bushing (622) and are arranged to follow the displacement of the pressure-sealed bonnet. Thus, independent of the position of the floating pressure-sealed bonnet (502, 602), the stem bushing guidance ensures the concentricity of the stem with the packing rings and / or O-rings (516, 616), which prevents any leakage between the stem (605) and the bonnet (602) in the case of Figure 6 or between the stem (505) and the body (501) in the case of Figure 5.

[0072] The internal pressure of the valve generates a stem piston effect (i.e., a load that pushes the stem outwards). This piston effect is counteracted by the external actuators (527, 627) and external thrust washers or bearings (515, 615) enclosed in brackets (526, 626). The brackets (526, 626) are directly bolted to the pressure-sealed body (501, 601). Therefore, and independently of the position of the floating pressure-sealed bonnet (502, 602), the external thrust washers or bearings (515, 615) lock the actuators (527, 627) and the stem (505, 605) in place along the stem axis and ensure a constant torque transmission engagement between the stem (505, 605) and the ball (518, 603). This constant engagement ensures that the total torque transmitted from the stem to the ball remains unchanged.

[0073] The valve has two seat assemblies, such as an upstream seat 620 and a downstream seat 624. The seat assemblies are inserted from a body / cover opening (e.g., an opening in the body 601 when the cover 602 is removed), which is independent of the cover position (facing the actuator or the body seal opposite the actuator), whether at the bottom or top of the valve assembly.

[0074] The valve seat assembly has the ability to be reduced or extended by using a cam integrated into the valve seat assembly, a thread integrated into the valve seat assembly, or by using external hydraulic pressure, pneumatic pressure, or vacuum (Figure 7). In the case of hydraulic pressure, pneumatic pressure, or vacuum, an external positive hydraulic, pneumatic, or vacuum pump is connected to the valve pressure seal body or the upstream valve seat. Starting the pump system changes the pressure within the upstream valve seat assembly or between the upstream valve seat assembly and the pressure seal body. This pressure change reduces the overall length of the upstream valve seat assembly and creates sufficient clearance within the body cavity and between the two valve seats for the ball to be inserted. Once the ball is correctly positioned between the two valve seats, the pump system is deactivated, and the upstream valve seat assembly gradually expands until the valve seat sealing surface contacts the ball. The disassembly process of the ball using a positive hydraulic, pneumatic, or vacuum pump is the reverse of the assembly process.

[0075] In cases where there is a threaded connection or cam profile connection within the upstream valve seat assembly or pressure sealing body, the ball assembly is operated manually, or, for larger sizes, with a wrench. The overall length of the valve seat is reduced to a sufficient clearance within the body cavity and between the two valve seats by hand or a wrench to engage the internal threaded connection, or by rotating the cam profile within the upstream valve seat assembly or pressure sealing body to insert the ball. Once the ball is correctly positioned between the two valve seats, the internal thread is disengaged, or the cam profile is rotated in the opposite direction until the upstream valve seat sealing surface contacts the ball. Disassembly of balls with internal threaded connections or internal cam profiles is the reverse of assembly. Figure 5A and Figure 6A Example cam devices 523 and 623 are shown in the figure.

[0076] Figure 7 illustrates a one-way seat assembly and a floating ball design configuration. The same approach can be applied to a two-way seat assembly and a trunnion ball design configuration. Once the ball is properly positioned between the two retracted seats, a cam system integrated into the seat, threads integrated into the seat, or external hydraulic, pneumatic, or vacuum pressure is used to extend the seat to the point where the seat sealing surface contacts the ball's spherical surface.

[0077] Figure 5B It shows the relationship with Figure 5A The same device, but the pressure sealing device and valve cover are located at the bottom of the valve and actuator assembly. Figure 6B It shows the relationship with Figure 6AThe same device, but the pressure sealing device and valve cover are located at the bottom of the valve and actuator assembly. Figure 5A and Figure 6A compared to, Figure 5B and Figure 6B The devices depicted do not alter the overall performance of the valve. These devices may be convenient for power plants with limited clearance above the valve, as such clearance does restrict or prevent maintenance of internal components from the top of the valve.

[0078] exist Figures 5A to 6B In the illustrated embodiment, by eliminating potential paths or through appropriate sealing structures, each potential path through which the high-pressure process flow in the valve flow path could leak into the surrounding environment is mitigated (e.g., from the valve stem connection through a through-hole in the body or between the valve stem and the valve stem seal). Although Figures 5A to 6B Each of these potential leakage paths in the illustrated embodiments is provided with a sealing structure that attempts to prevent or limit actual leakage, but such seals may not be 100% effective and / or may deteriorate over time, thus allowing some leakage. Figures 5A to 6B The illustrated implementation allows for the replacement of each individual seal with a series of seals to further reduce the risk of leakage over time.

[0079] exist Figures 5A to 6B In each of the example embodiments, the valve body is preferably machined from a single piece of metal. The valve cover is also preferably machined from a single piece of metal. This two-piece valve body structure reduces potential leakage paths to only two: (1) a path passing between the body and the valve cover, and (2) a path passing between the valve cover and the valve stem. Figures 5A to 6B All embodiments shown allow the torque monitoring transducer to be mounted (permanently or temporarily) on the valve stem, actuator, or bracket, or at the interface between these components, to monitor the resulting valve operating torque. Figures 5A to 6B All the embodiments shown allow for the (permanent or temporary) mounting of angular position monitoring transducers to the valve stem, actuator, or bracket, or to the interface between these components, to monitor the ball's position. Acoustic transducers may also be mounted on the body near the valve seat (or bonnet) to detect acoustic signals caused by leakage of steam, liquid, or gas through the valve seat or bonnet. One or more pressure sensor transducers may also be connected to monitor pressure within the internal body cavity, including possible pressure differences between the valve inlet and body cavity, or between the body cavity and valve outlet. Furthermore, electrical outputs from one or more such sensors are connected to a data acquisition system capable of locally or remotely accessing such measurement data.

[0080] Additionally, because the ball is inserted from the top during valve assembly (before the bonnet is locked into the body opening by the pressure sealing gasket retainer), the dimensions of the ball and / or body (relative to the valve's envelope dimensions and the external constraints imposed on the valve) do not unduly restrict the length and / or diameter of the valve stem. This allows the valve stem to extend upward through the stem sealing device within the bonnet, including multiple packing gland stem seal assemblies, and possibly via an intermediate actuator to connect upward to an external thrust bearing (this not only reduces rotational friction but also provides a downward-pointing force to help properly position the valve stem within the valve assembly). As will be understood, the top-mounted design also allows the valve stem itself to extend directly to the external thrust bearing (i.e., without an intermediate actuator).

[0081] Figures 5A to 6B In any example implementation, the valve stem can be a separate structure attached to a floating or trunnion-mounted ball. Alternatively, the valve stem and ball can be made as a single, integral part to increase strength and reduce the number of parts to be assembled.

[0082] Figures 5A to 6B The embodiment shown depicts a single ball and a pair of seats within a body made from a single piece of metal. However, the body can be made from a longer or larger single piece of metal to have multiple body cavities and a top opening to accommodate multiple balls and mating pairs of seats. The body can be designed such that the balls and mating pairs of seats are connected in series or in parallel.

[0083] In all two-piece valve body examples, the body and bonnet may each be machined from a single piece of suitable hard metal, such as carbon steel, corrosion-resistant austenitic stainless steel, nickel-based steel, or similar metals required for specific service processes. Each of the valve body components may be machined from raw materials (forged or cast) or manufactured using additive manufacturing processes, including 3D printing. The internal "wet" surfaces of the valve body, bonnet, ball, seat, etc., which are subjected to service process flows are protected by a corrosion-resistant coating of stainless steel (or a similar corrosion-resistant metal or metal alloy suitable for the service process), or by a stainless steel sleeve (or a similar corrosion-resistant metal or metal alloy), or by a hard coating similar to the hard coating used between the ball and seat sealing surfaces, or a combination of these, for power / nuclear service applications (e.g., saturated steam, superheated steam, steam condensate, water, gas, and / or similar harsh industrial service applications). The stainless steel surface coating may be applied by welding or other processes. In some implementations, as described above, sleeves made of stainless steel or any corrosion-resistant material can be fixed to a hard metal (e.g., carbon steel LF2) body shell using welding and complex geometries. Interconnection of the stainless steel sleeves can be achieved by welding between each sleeve.

[0084] In one embodiment, a top-mounted ball valve is provided for harsh industrial applications such as power and nuclear applications. The top-mounted valve includes: a one-piece metal body; a rotatable metal valve structure; a top opening disposed on the body and sized to receive entry into the metal valve structure and its associated valve seat; a one-piece metal valve cover configured for pressure-sealing connection to the top of the body; and a rotatable valve-operated stem integrally with or operatively connected to the top of the metal valve structure to rotate the metal valve structure upon rotation of the stem.

[0085] The rotatable metal valve structure can be assembled within the body and between metal valve seats, which are also assembled into the body. The valve seats and the metal valve structure form a metal-to-metal sealing engagement. The metal valve structure has a through-hole for allowing fluid flow when in a predetermined open rotation position and blocking fluid flow when in a predetermined closed rotation position.

[0086] According to the top-mounted valve described in the first two paragraphs above, the pressure-sealed connection between the body and the valve cover includes a circular retaining mechanism that acts as a barrier to prevent the valve cover and pressure-sealing gasket from leaving the valve. Alternatively, according to the top-mounted valve described in the first two paragraphs above, the valve cover and the pressure seal are mounted on the side of the body opposite to the operator. Alternatively, according to the top-mounted valve described in the first two paragraphs above, the valve cover and the pressure seal are mounted on the side of the body facing the operator.

[0087] According to the top-mounted valve described in the preceding paragraph, the valve cover and the pressure seal are mounted on the operator-facing side of the body, and the body includes a through-hole on the opposite side of the top opening to receive a valve stem and a valve stem sealing device, the valve stem sealing device including a pair of rotor seals circumferentially disposed around the rotatable valve stem.

[0088] According to the top-mounted valve described in the preceding paragraph, the valve cover and the pressure seal are mounted on the operator-facing side of the body. Furthermore, the valve cover includes a through-hole to receive a valve stem and a valve stem sealing device, the valve stem sealing device comprising a pair of rotor seals circumferentially disposed around the rotatable valve stem.

[0089] According to the top-mounted valve described in the preceding paragraph, the valve is configured to allow the operator direct access to replace the entire metal valve structure, its associated valve seat, and the valve stem without removing the valve's actuator or support.

[0090] According to the top-mounted valve described in the previous paragraph, the valve stem and the main body through-hole are kept concentric by an encapsulated valve stem bushing.

[0091] According to the top-mounted valve described in the previous paragraph, the valve stem and the pressure-sealed valve cover through-hole are kept concentric by an encapsulated valve stem bushing.

[0092] According to the top-mounted valve described in either of the first two paragraphs, the valve stem is held in the proper position in the valve and mated with the metal valve structure by means of an external bracket bolted to the body, an external thrust bearing encapsulated within the bracket, and an actuator in contact with the thrust bearing.

[0093] According to the top-mounted valve described in paragraph 8 above, the valve seat assembly has an overall length adjustable by external hydraulic or pneumatic pressure or vacuum, or by threads between sub-components of the valve seat assembly, or by cam profiles between sub-components of the valve seat assembly, wherein adjustment is completed when the pressure-sealed valve cover is not physically attached to the body.

[0094] According to the top-mounted valve described in the previous paragraph, when the total length of the valve seat assembly is reduced, the metal valve structure, the upper trunnion bearing, and the lower trunnion bearing can be assembled between the two valve seat assemblies.

[0095] According to the top-mounted valve described in the previous paragraph, when the total length of the valve seat assembly increases, the metal valve structure and the valve seat are configured to act as a sealing barrier.

[0096] According to the top-mounted valve described in paragraph 11 above, the metal valve structure is a spherical structure with a through-hole for allowing valve-controlled process fluid to pass through.

[0097] According to the top-mounted valve described in paragraph 12 above, the spherical structure is a floating ball connected to a separately formed valve stem structure on the top side.

[0098] According to the top-mounted valve described in paragraph thirteen above, the spherical structure and the valve stem structure are combined together to form a single integral structure.

[0099] According to the top-mounted valve described in paragraph fourteen above, the spherical structure includes trunnion-mounted cylindrical portions located on opposite top and bottom sides, which abut between the sphere and the body. According to the top-mounted valve described in paragraph 15 above, the top-mounted valve includes an internally movable member that is spring-loaded toward the center of the valve. According to the top-mounted valve described in paragraph sixteen above, the body and the valve cover are held together with the pressure sealing device and the pressure sealing gasket retainer.

[0100] According to the top-mounted valve described in paragraph seventeen above, the metal valve structure is a rotatable cylindrical or conical plug structure.

[0101] According to the top-mounted valve described in paragraph 18 above, one or more wetted surfaces of the body and the valve cover are protected by a corrosion-resistant sleeve.

[0102] In one embodiment, a method for manufacturing a top-mounted valve for power and nuclear industry applications is provided.

[0103] The method includes: providing an integral metal valve body with a top opening; providing a rotatable metal valve structure sized to be assembled through the top opening of the valve body; and assembling the metal valve structure within the body and between metal valve seats through the top opening, the metal valve seats also being assembled into the body through the top opening. The valve seats and the metal valve structure form a metal-to-metal sealed engagement, the metal valve structure having a through-hole for allowing fluid flow in a predetermined open rotational position and blocking fluid flow in a predetermined closed rotational position.

[0104] The method further includes: providing an integral metal valve cover configured for pressure-sealing connection to the top of the body; providing a through-hole in the body or the valve cover; and assembling a rotatable valve-operating stem within the rotating body seal around its circumference through the body or the valve cover, the valve-operating stem being integrally or operably connected to the top of the metal valve structure so as to rotate the metal valve structure when the valve stem rotates.

[0105] The methods in the first two paragraphs can be used to construct and / or deploy valves according to any one or more of the sections between paragraphs twenty-three and four above.

[0106] While the above examples employ metal balls and metal seats, in another example, these components could be made of ceramic or polymer materials. Manufacturing these components using ceramic or polymer materials will affect their envelope dimensions, the overall size of the valve, and the limits of temperature operation. However, the example design concept can be adapted to allow for the interchangeability of metal and ceramic balls, as well as metal, ceramic, and polymer seats, within the same body of existing examples.

[0107] While the invention has been described in conjunction with what is now considered the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments, but rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. As those skilled in the art will understand, some individual features of one exemplary embodiment may also be used in another exemplary embodiment.

Claims

1. A top-mounted ball valve for use in harsh industrial applications, particularly in power and nuclear applications, the top-mounted valve comprising: One-piece metal body; A rotatable metal valve structure is assembled within the body and between metal valve seats, which are also assembled into the body. The valve seats and the metal valve structure form a metal-to-metal sealing engagement. The metal valve structure has a through-hole for allowing fluid flow when in a predetermined open rotational position and blocking fluid flow when in a predetermined closed rotational position. The body includes a top opening sized to receive the metal valve structure and its associated valve seat. An integral metal valve cover, the metal valve cover being configured for a pressure-sealed connection to the top of the body; as well as A rotatable valve operating stem, which is integral with or operatively connected to the top of the metal valve structure so as to rotate the metal valve structure when the valve stem is rotated.

2. The top-mounted valve according to claim 1, wherein, The pressure-sealed connection between the body and the valve cover includes a circular retaining mechanism that acts as a barrier to prevent the valve cover and pressure-sealing gasket from leaving the valve.

3. The top-mounted valve according to claim 2, wherein, The valve cover and the pressure seal are mounted on the side of the body opposite to the operator.

4. The top-mounted valve according to claim 2, wherein, The valve cover and the pressure seal are mounted on the operator-facing side of the main body.

5. The top-mounted valve according to claim 4, wherein, The body includes a through-hole on the opposite side of the top opening to receive a valve stem and a valve stem sealing device, the valve stem sealing device including a pair of rotor seals arranged circumferentially around the rotatable valve stem.

6. The top-mounted valve according to claim 4, wherein, The valve cover includes a through-hole to receive a valve stem and a valve stem sealing device, the valve stem sealing device including a pair of rotor seals arranged circumferentially around the rotatable valve stem.

7. The top-mounted valve according to claim 6, wherein, The valve is configured to allow the operator direct access to replace the entire metal valve structure, its associated valve seat, and the valve stem without removing the valve's actuator or support.

8. The top-mounted valve according to claim 6, wherein, The valve stem is kept concentric with the body through-hole by using an encapsulated valve stem bushing.

9. The top-mounted valve according to claim 6, wherein, The valve stem is kept concentric with the pressure-sealed valve cover through-hole by using an encapsulated valve stem bushing.

10. The top-mounted valve according to claim 8 or claim 9, wherein, The valve stem is held in the proper position in the valve and mated with the metal valve structure by means of an external bracket bolted to the body, an external thrust bearing encapsulated within the bracket, and an actuator in contact with the thrust bearing.

11. The top-mounted valve according to claim 1, wherein, The valve seat assembly has an overall length that can be adjusted using external hydraulic or pneumatic pressure or vacuum, or threads between sub-components of the valve seat assembly, or cam profiles between sub-components of the valve seat assembly, wherein adjustment is performed when the pressure-sealed valve cover is not physically attached to the body.

12. The top-mounted valve according to claim 11, wherein, When the total length of the valve seat assembly is reduced, the metal valve structure, the upper trunnion bearing, and the lower trunnion bearing can be assembled between the two valve seat assemblies.

13. The top-mounted valve according to claim 12, wherein, As the overall length of the valve seat assembly increases, the metal valve structure and the valve seat are configured to act as a sealing barrier.

14. The top-mounted valve according to claim 1, wherein, The metal valve structure is a spherical structure with a through-hole for allowing valve-controlled process fluid to pass through.

15. The top-mounted valve according to claim 1, wherein, The spherical structure is a floating sphere connected to a separately formed valve stem structure on the top side.

16. The top-mounted valve according to claim 1, wherein, The spherical structure and the valve stem structure are combined together to form a single integral structure.

17. The top-mounted valve according to claim 1, wherein, The spherical structure includes trunnion-mounted cylindrical portions located on opposite top and bottom sides, which abut between the sphere and the body.

18. The top-mounted valve of claim 1, wherein the top-mounted valve includes an internally movable member that is spring-loaded toward the center of the valve.

19. The top-mounted valve according to claim 1, wherein, The main body and the valve cover are held together with the pressure sealing device and the pressure sealing gasket retainer.

20. The top-mounted valve according to claim 1, wherein, The metal valve structure is a rotatable cylindrical or conical plug structure.

21. The top-mounted valve according to claim 1, wherein, One or more wetted surfaces of the body and the valve cover are protected with a corrosion-resistant sleeve.

22. A method for manufacturing a top-mounted valve for power and nuclear industry applications, the method comprising: Provides a one-piece metal valve body with a top opening; A rotatable metal valve structure is provided, the metal valve structure being sized to fit through the top opening of the valve body. The metal valve structure is assembled within the body and between metal valve seats through the top opening. The metal valve seats are also assembled into the body through the top opening. The valve seats and the metal valve structure form a metal-to-metal sealing engagement. The metal valve structure has a through-hole for allowing fluid flow when in a predetermined open rotation position and blocking fluid flow when in a predetermined closed rotation position. An integral metal valve cover is provided, the metal valve cover being configured for pressure-sealing connection to the top of the body; A through hole is provided in the body or the valve cover; A rotatable valve-operating stem is assembled around the circumference of the rotating body seal via the body or the valve cover. The valve-operating stem is integral with or operably connected to the top of the metal valve structure so as to rotate the metal valve structure when the stem rotates.

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