SEAT FOR GATE VALVE

A gate valve can include a valve body and a bore positioned within the valve body, where the bore traverses a width of the valve body and comprises an inlet and an outlet. The gate valve can also include a gate slidably disposed within the bore. The gate valve can further include a seat disposed around the bore and adjacent to the gate and the valve body, where the seat includes a seat body having a spring system and an inner surface, where the inner surface is adjacent to the gate, where the spring system includes a cavity disposed in the seat body and a spring section positioned between the cavity and the inner surface, where the spring section protrudes outward relative to the inner surface, where the spring section is configured to move inward and reduce a volume of the cavity when the gate contacts the spring section.

TECHNICAL FIELD

The present application is related to gate valves and, more particularly, to seats for gate valves.

BACKGROUND

Some gate valves are designed for full differential with the gate using solid seats. These valves often use one or more seals to create contact pressure between the seat and the gate of the gate valve. Such seal designs in the current art, however, tend to fail at the relatively low pressures (i.e., when a fluid in the bore of the gate valve is at a relatively low pressure) because the contact pressure interface is limited in light of the full differential requirements. In some cases, industry standards require 10% of rated working pressure (RWP) as an acceptable low pressure limit. In real world conditions, most of the in-service time of a gate valve is under low pressure conditions, and so the design of gate valves in the current art leads to high rates of failure.

SUMMARY

In general, in one aspect, the disclosure relates to a gate valve that includes a valve body and a bore positioned within the valve body, where the bore traverses a width of the valve body and includes an inlet and an outlet. The gate valve can also include a gate slidably disposed within the bore between the inlet and the outlet, where the gate, when in a first position within the bore, is configured to allow a fluid to flow within the bore from the inlet to the outlet, and where the gate, when in a second position within the bore, is configured to prevent a fluid from flowing therethrough from the inlet to the outlet. The gate valve can further include a seat disposed around the bore and adjacent to the gate and the valve body, where the seat includes a seat body having a spring system, an inner surface, and an outer surface, where the inner surface is adjacent to the gate, where the outer surface is adjacent to the valve body, where the spring system comprises a cavity disposed in the seat body and a spring section positioned between the cavity and the inner surface, where the spring section protrudes outward relative to the inner surface, where the spring section is configured to move inward and reduce a volume of the cavity when the gate contacts the spring section, and where the spring section is configured to revert to its default position, thereby allowing the volume of the cavity to be restored, when the gate avoids contacting the spring section.

In another aspect, the disclosure relates to a seat for a gate valve that includes a seat body having an inner surface and an outer surface, where the inner surface is configured to be adjacent to a gate of the gate valve, where the outer surface is configured to be adjacent to a valve body of the gate valve. The seat can also include a spring system, which can include a cavity disposed within the seat body and a spring section positioned between the cavity and the inner surface, where the spring section includes a protrusion that is tapered toward a bottom end of the seat body, where the protrusion protrudes outward relative to the inner surface, where the spring section is configured to move inward and reduce a volume of the cavity when the gate of the gate valve contacts the protrusion, and where the spring section is configured to revert to its default position, thereby allowing the volume of the cavity to be restored, when the gate of the gate valve no longer contacts the protrusion.

DESCRIPTION OF THE INVENTION

The example embodiments discussed herein are directed to systems, apparatus, methods, and devices for seats for gate valves. Gate valves with example seats can be used in any of a number of industries, including but not limited to oil and gas, petrochemical, marine, power generation, petroleum refining, wastewater, automotive, pharmaceutical, and mechanical construction. Gate valves with example seats may be designed to comply with certain standards and/or requirements.

Gate valves with example seats may be used in any of a number of different environments, including but not limited to indoors, outdoors, a manufacturing plant, a warehouse, and a storage facility, any of which can be climate-controlled or non-climate-controlled. In some cases, gate valves with the example seats discussed herein can be used in any type of hazardous environment, including but not limited to an airplane hangar, a drilling rig (as for oil, gas, or water), a production rig (as for oil or gas), a refinery, a chemical plant, a power plant, a mining operation, a wastewater treatment facility, and a steel mill.

The use of the terms “about”, “approximately”, and similar terms applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numeric values (i.e., having the equivalent function or result). For example, this term may be construed as including a deviation of +10 percent of the given numeric value provided such a deviation does not alter the end function or result of the value. Therefore, a value of about 1% may be construed to be a range from 0.9% to 1.1%. Furthermore, a range may be construed to include the start and the end of the range. For example, a range of 10% to 20% (i.e., range of 10%-20%) includes 10% and also includes 20%, and includes percentages in between 10% and 20%, unless explicitly stated otherwise herein. Similarly, a range of between 10% and 20% (i.e., range between 10%-20%) includes 10% and also includes 20%, and includes percentages in between 10% and 20%, unless explicitly stated otherwise herein.

It is understood that when combinations, subsets, groups, etc. of elements are disclosed (e.g., combinations of components in a composition, or combinations of steps in a method), that while specific reference of each of the various individual and collective combinations and permutations of these elements may not be explicitly disclosed, each is specifically contemplated and described herein. By way of example, if an item is described herein as including a component of type A, a component of type B, a component of type C, or any combination thereof, it is understood that this phrase describes all of the various individual and collective combinations and permutations of these components. For example, in some embodiments, the item described by this phrase could include only a component of type A. In some embodiments, the item described by this phrase could include only a component of type B. In some embodiments, the item described by this phrase could include only a component of type C. In some embodiments, the item described by this phrase could include a component of type A and a component of type B. In some embodiments, the item described by this phrase could include a component of type A and a component of type C. In some embodiments, the item described by this phrase could include a component of type B and a component of type C. In some embodiments, the item described by this phrase could include a component of type A, a component of type B, and a component of type C. In some embodiments, the item described by this phrase could include two or more components of type A (e.g., A1and A2). In some embodiments, the item described by this phrase could include two or more components of type B (e.g., B1and B2). In some embodiments, the item described by this phrase could include two or more components of type C (e.g., C1and C2). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type A (A1and A2)), optionally one or more of a second component (e.g., optionally one or more components of type B), and optionally one or more of a third component (e.g., optionally one or more components of type C). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type B (B1and B2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g., optionally one or more components of type C). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type C (C1and C2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g., optionally one or more components of type B).

A user may be any person that interacts with gate valves, regardless of the environment in which the gate valve is located and/or the industry in which the gate valve is used. Examples of a user may include, but are not limited to, an engineer, an electrician, an instrumentation and controls technician, a mechanic, an operator, an employee, a consultant, a contractor, and a manufacturer's representative.

Gate valves with example seats (including portions thereof) can be made of one or more of a number of suitable materials to allow the gate valves to meet certain standards and/or regulations while also maintaining durability in light of the one or more conditions under which the gate valves and/or other associated components of the gate valves can be exposed. Examples of such materials can include, but are not limited to, aluminum, stainless steel, fiberglass, glass, plastic, thermoplastic, ceramic, and rubber.

When used in certain systems (e.g., for certain subsea field operations), gate valves with example seats can be designed to comply with certain standards and/or requirements. Examples of entities that set such standards and/or requirements can include, but are not limited to, the Society of Petroleum Engineers, the American Petroleum Institute (API), the International Standards Organization (ISO), the International Association of Classification Societies (IACS), and the Occupational Safety and Health Administration (OSHA). For example, a gate valve with example seats can comply with API 6A standards.

Example seats, or portions or components thereof, described herein can be made from a single piece (e.g., as from a mold, injection mold, casting, die cast, forging, extrusion process, or 3D printing). In addition, or in the alternative, example access seats (including portions or components thereof) can be made from multiple pieces that are mechanically coupled to each other. In such a case, the multiple pieces can be mechanically coupled to each other using one or more of a number of coupling methods, including but not limited to epoxy, welding, fastening devices, compression fittings, mating threads, snap fittings, and slotted fittings. One or more pieces that are mechanically coupled to each other can be coupled to each other in one or more of a number of ways, including but not limited to fixedly, hingedly, removeably, slidably, and threadably.

Components and/or features described herein can include elements that are described as coupling, fastening, securing, abutting against, in communication with, or other similar terms. Such terms are merely meant to distinguish various elements and/or features within a component or device and are not meant to limit the capability or function of that particular element and/or feature. For example, a feature described as a “coupling feature” can couple, secure, fasten, abut against, and/or perform other functions aside from merely coupling.

A coupling feature (including a complementary coupling feature) as described herein can allow one or more components and/or portions of an example seat to become coupled, directly or indirectly, to one or more other components of the seat and/or to some other component of a gate valve. A coupling feature can include, but is not limited to, a clamp, a portion of a hinge, an aperture, a recessed area, a protrusion, a hole, a slot, a tab, a detent, and mating threads. One portion of an example seat can be coupled to another component of the seat and/or to some other component of a gate valve the direct use of one or more coupling features.

In addition, or in the alternative, a portion of an example seat can be coupled to another component of the seat and/or to another component of a gate valve using one or more independent devices that interact with one or more coupling features disposed on a component of the example seat. Examples of such devices can include, but are not limited to, a pin, a hinge, a fastening device (e.g., a bolt, a screw, a rivet), epoxy, glue, adhesive, and a spring. One coupling feature described herein can be the same as, or different than, one or more other coupling features described herein. A complementary coupling feature as described herein can be a coupling feature that mechanically couples, directly or indirectly, with another coupling feature.

If a component of a figure is described but not expressly shown or labeled in that figure, the label used for a corresponding component in another figure may be inferred to that component. Conversely, if a component in a figure is labeled but is not described, the description for such component may be substantially the same as the description for the corresponding component in another figure. The numbering scheme for the various components in the figures herein is such that each component is a three-digit number or a four-digit number, and corresponding components in other figures have the identical last two digits. For any figure shown and described herein, one or more of the components may be omitted, added, repeated, and/or substituted. Accordingly, embodiments shown in a particular figure should not be considered limited to the specific arrangements of components shown in such figure.

Further, a statement that a particular embodiment (e.g., as shown in a figure herein) does not have a particular feature or component does not mean, unless expressly stated, that such embodiment is not capable of having such feature or component. For example, for purposes of present or future claims herein, a feature or component that is described as not being included in an example embodiment shown in one or more particular drawings is capable of being included in one or more claims that correspond to such one or more particular drawings herein.

Example embodiments of seats for gate valves will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of seats for gate valves are shown. Seats for gate valves may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of seats for gate valves to those of ordinary skill in the art. Like, but not necessarily the same, elements (also sometimes called components) in the various figures are denoted by like reference numerals for consistency.

Terms such as “first”, “second”, “primary,” “secondary,” “above”, “below”, “inner”, “outer”, “distal”, “proximal”, “end”, “top”, “bottom”, “upper”, “lower”, “side”, “width,”, “height”, “depth”, “length”, “left”, “right”, “front”, “rear”, and “within”, when present, are used merely to distinguish one component (or part of a component or state of a component or orientation of a component) from another. This list of terms is not exclusive. Such terms are not meant to denote a preference or a particular orientation, and they are not meant to limit embodiments of seats for gate valves. In the following detailed description of the example embodiments, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

FIG.1shows a sectional view of a gate valve100with which example embodiments may be used. The gate valve100in this example includes a valve body102, a bore108, a valve trim110, and one or more seats120. The valve body102of the gate valve100can have any of a number of configurations (e.g., shape, size, thickness) suitable for the particular use, environment, and/or industry for the gate valve100. The valve body102can form a proximal receiving area113and a distal receiving area111for the gate115and/or other parts of the valve trim110. The proximal receiving area113can be filled with one or more fluids (e.g., water, air, oil). Similarly, the distal receiving area111can be filled with one or more fluids (e.g., water, air, oil), which can be the same as or different than the one or more fluids within the proximal receiving area113.

The proximal receiving area113can be configured to receive one or more components (including portions thereof) of the valve trim110. Examples of components of the valve trim110that are received by the proximal receiving area113can include, but are not limited to, the actuator (e.g., a handle, a piston, a hydraulic assembly), the stem112, and the gate115. The actuator of the valve trim110can be operated manually, hydraulically, electrically, and/or by some other means. The proximal receiving area113can also be configured to receive, or be adjacent to, a portion (e.g., the top portion) of one or more of the seats120. In this case, the top portions of seat120-1and seat120-2bound part of the bottom of the proximal receiving area113.

The components (or portions thereof) of the valve trim110that are within the proximal receiving area113of the gate valve100can vary based on the position of the gate valve100. For example, when the gate valve100is in the open position, less of the stem112and more of the gate115are positioned within the proximal receiving area113. As another example, when the gate valve100is in the closed position, as shown inFIG.1, more of the stem112and less of the gate115are positioned within the proximal receiving area113.

The proximal receiving area113can be sealed (e.g., using gaskets, caulk, O-rings, and/or other sealing members and/or devices) so that elements (e.g., fluids, dirt) from outside the gate valve100are prevented from entering the proximal receiving area113. The dimensions (e.g., the height, the width, the cross-sectional shape when viewed from above) of the proximal receiving area113can be configured in such a way that the full range of motion (between fully open and fully closed) of the gate115can freely occur without being obstructed within the proximal receiving area113.

The distal receiving area111can be configured to receive one or more components (including portions thereof) of the valve trim110. Examples of components of the valve trim110that are received by the distal receiving area111can include, but are not limited to, the gate115. The distal receiving area111can also be configured to receive, or be adjacent to, a portion (e.g., the bottom portion) of one or more of the seats120. In this case, the bottom portions of seat120-1and seat120-2bound part of the top of the distal receiving area111.

The components (or portions thereof) of the valve trim110that are within the distal receiving area111of the gate valve100can vary based on the position of the gate valve100. For example, when the gate valve100is in the open position, only the distal end (below the hole) of the gate115is positioned within the distal receiving area111. As another example, when the gate valve100is in the closed position, as shown inFIG.1, all of the distal end of the gate115and all of the hole116in the gate115are positioned within the distal receiving area111.

The distal receiving area111can be sealed (e.g., using gaskets, caulk, O-rings, and/or other sealing members and/or devices) so that elements (e.g., fluids, dirt) from outside the gate valve100are prevented from entering the distal receiving area111. The dimensions (e.g., the height, the width, the cross-sectional shape when viewed from above) of the distal receiving area111can be configured in such a way that the full range of motion (between fully open and fully closed) of the gate115can freely occur without being obstructed within the distal receiving area111.

The bore108of the gate valve100is positioned within the valve body102. In this case, the bore108traverses a width of the valve body102. The bore108of the gate valve100includes an inlet104that is part of an upstream bore potion108-1of the bore108and an outlet106that is part of a downstream bore portion108-2of the bore108. The bore108can be cylindrical (have a circular cross-sectional shape) along its entire length. Alternatively, the bore108can have one or more of a number of other cross-sectional shapes along some or all of its length. The cross-sectional area of the bore108can be substantially constant along its length or differ at one or more points along its length.

Dividing the bore108into the upstream bore potion108-1and the downstream bore portion108-2is the gate115. As discussed above, the gate115has a hole116that traverses the thickness of the gate115. The hole116can have the same characteristics (e.g., shape, width, height, cross-sectional area) as the distal end (adjacent to the gate115) of the upstream bore potion108-1and the proximal end (adjacent to the gate115) of the downstream bore portion108-2. When the gate valve100is in the open position (i.e., a fully open position), the center of the hole116in the gate115is substantially aligned with the axial centers of the upstream bore potion108-1and the downstream bore portion108-2. When the gate valve100is in the closed position (i.e., a fully closed position), the gate115completely covers the upstream bore potion108-1and the downstream bore portion108-2, and no part of the hole116in the gate115intersects the upstream bore potion108-1or the downstream bore portion108-2of the bore108.

For the gate valve100to transition between the closed position and the open position, the gate115is slidably (or otherwise movably) disposed within the bore108between the inlet104(the upstream bore portion108-1) and the outlet106(the downstream bore portion108-2). When the gate valve100is open (when the gate115is in a position within the bore108that aligns the hole116with the bore108), fluid can be allowed to flow within the bore108from the inlet104to the outlet106. When the gate valve100is closed (when the gate is in a position within the bore108that completely blocks the bore108with the gate115), fluid is prevented from flowing through to gate115within the bore108from the inlet104to the outlet106.

In this case, the gate valve100has two seats120that are located on either side of the gate115. The seat120-1is cylindrically shaped in this case, withFIG.1showing a sectional side view of the seat120-1. The seat120-1is positioned around the upstream bore portion108-1of the bore108and adjacent to (between) the gate115and the valve body102. The seat120-1includes a seat body121-1having an inner surface151-1and an outer surface152-1, where the inner surface151-1is adjacent to the gate115, and where the outer surface152-1is adjacent to the valve body102. The seat120-1can include one or more features to ensure a sufficient seal between the gate115and/or the valve body102to ensure that no fluids and/or other contaminants can pass therebetween. For example, along the outer surface152-1of the seat120-1are two sealing members125that make contact with the valve body102. Sealing member125-1is positioned close to the inner perimeter of the seat body121-1, and sealing member125-2is positioned close to the outer perimeter of the seat body121-1.

In this case, the inner surface151-1of the seat body121-1has no features. In the current art, the seat body121-1is made of metal. As such, the inner surface151-1of the seat body121-1forms a metal-to-metal seal with the gate115. Both the inner surface151-1of the seat body121-1and the adjacent surface of the valve body102can be smooth, planar, and highly polished in order to provide a more effective metal-to-metal seal. When the gate valve100has multiple seats120, the characteristics (e.g., shape, size, material, types of sealing members, location of sealing members) of one seat120can be the same as, or different than, the corresponding characteristics of one or more of the other seats120.

Seat120-2is cylindrically shaped in this case, withFIG.1showing a sectional side view of the seat120-2. The seat120-2is positioned around the downstream bore portion108-2of the bore108and adjacent to (between) the gate115and the valve body102. The seat120-2includes a seat body121-2having an inner surface151-2and an outer surface152-2, where the inner surface151-2is adjacent to the gate115, and where the outer surface152-2is adjacent to the valve body102. The seat120-2can include one or more features to ensure a sufficient seal between the gate115and/or the valve body102to ensure that no fluids and/or other contaminants can pass therebetween. For example, along the outer surface152-2of the seat120-2are two sealing members125that make contact with the valve body102. Sealing member125-3is positioned close to the inner perimeter of the seat body121-2, and sealing member125-4is positioned close to the outer perimeter of the seat body121-2.

In this case, the inner surface151-2of the seat body121-2has no features. In the current art, the seat body121-2is made of metal. As such, the inner surface151-2of the seat body121-2forms a metal-to-metal seal with the gate115. Both the inner surface151-2of the seat body121-2and the adjacent surface of the valve body102can be smooth, planar, and highly polished in order to provide a more effective metal-to-metal seal.

The sealing members125of the seats120can have any of a number of features, components, and/or configurations to allow the sealing members125to provide a solid seal with the valve body102. For example, a sealing member125can be or include an elastomeric gasket with one or more small springs inside the gasket. For example, a sealing member125can be or include a pressure-energized lip seal with a spring (sometimes called a lip spring). As another example, a sealing member125can be or include a pressure-energized elastomer. When a seat120has multiple sealing members125, the characteristics (e.g., shape, size, material, orientation, configuration) of one sealing member125can be the same as, or different than, one or more of the corresponding characteristics of one or more of the other sealing members125.

The contact seal between a seat120-2and gate115as well as the seat120and the valve body102on the downstream side can be designed for full differential pressure between upstream and downstream of the gate115. In such cases, if there is too much metal-to-metal contact area and the pressure is not high enough, the seal between the seat120-2and the gate115is not sufficient (i.e., there is not enough force to sustain the seal through the metal-to-metal contact). Also, in such cases, if there is too low of a metal-to-metal contact area between the seat120-2and the gate115and the pressure is too high, cracks and other mechanical failures can result. It is not feasible to increase the size of the spring in the sealing members125because the contact area between the seat120-2and the gate115is too large and it is not possible to have a spring that creates a high enough force in light of factors like the size of the pocket space and movement of the gate115. Example embodiments incorporate a seal design into the inner surface151-2(also called the face) of the seat120-2.

FIG.2shows a sectional view of part of a gate valve200with the gate215in the open position for use with certain example embodiments. The gate valve200includes a valve body202, a bore208, a valve trim210, and two seats (seat220and seat320). These components of the gate valve200, including portions thereof, can be substantially the same as the valve body102, the bore108, the valve trim110, and the seats120(including corresponding portions thereof) discussed above with respect toFIG.1. For example, the valve body202can form a proximal receiving area213and a distal receiving area211for the gate215and/or other parts of the valve trim210. The proximal receiving area213can be filled with one or more fluids (e.g., water, air, oil). Similarly, the distal receiving area211can be filled with one or more fluids (e.g., water, air, oil), which can be the same as or different than the one or more fluids within the proximal receiving area213.

In this case, only the gate215with the hole216of the valve trim210is shown in FIGS.2and3. The proximal receiving area213can also be configured to receive, or be adjacent to, a portion (e.g., the top portion) of one or more of the seats220. In this case, the top portions of the seat220and the seat320bound part of the bottom of the proximal receiving area213. Similarly, the bottom portions of the seat220and the seat320bound part of the top of the distal receiving area211.

When the gate215is in the open position, the hole216in the gate215is aligned with the bore208, thereby allowing a fluid288to flow from the upstream bore portion208-1of the bore208, through the hole216in the gate215, and through the downstream bore portion208-2of the bore208. Under this operating condition, the pressure is uniform throughout the bore208(absent a blockage from some external source), and so there is no pressure differential between the upstream bore portion208-1and the downstream bore portion208-2. Also, since the gate215is not directly exposed to the fluid288flowing through the bore208when the gate valve200is open, the gate215does not apply any lateral pressure to the seat220or the seat320. When the gate valve200is open, the gate215makes full contact with most, but not all, of the inner surface251of the seat220and with most, but not all, of the inner surface351of the seat320.

Seat220and seat320are located on either side of the gate215. The seat220and the seat320in this case are configured substantially identically to each other. For example, the seat220and the seat320are each cylindrically shaped in this case, withFIG.2showing a sectional side view of them. The seat220is positioned around the upstream bore portion208-1of the bore208and adjacent to (between) the gate215and the valve body202. The seat220includes a seat body221having an inner surface251and an outer surface252, where the inner surface251is adjacent to the gate215, and where the outer surface252is adjacent to the valve body202. Along the outer surface252of the seat220are two sealing members225that make contact with the valve body202. Sealing member225-1is positioned close to the inner perimeter of the seat body221, and sealing member225-2is positioned close to the outer perimeter of the seat body221. The inner surface251of the seat body221and the surface of the adjacent wall of the valve body202have no features.

Similarly, the seat320is positioned around the downstream bore portion208-2of the bore208and adjacent to (between) the gate215and the valve body202. The seat320includes a seat body321having an inner surface351and an outer surface352, where the inner surface351is adjacent to the gate215, and where the outer surface352is adjacent to the valve body202. Along the outer surface352of the seat320are two sealing members325that make contact with the valve body202. Sealing member325-1is positioned close to the inner perimeter of the seat body321, and sealing member325-2is positioned close to the outer perimeter of the seat body321. The inner surface351of the seat body321and the surface of the adjacent wall of the valve body202have no features.

FIG.3shows a sectional view of the part of the gate valve200ofFIG.2with the gate215in the closed position for use with certain example embodiments. When the gate valve200is fully closed, the gate215is moved downward further into the distal receiving area211until the hole216in the gate is disposed entirely in the distal receiving area211and has not intersection with the bore208. The part of the gate215above the hole216completely covers the bore208, and also makes full contact with all of the inner surface251of the seat220and with all of the inner surface351of the seat320.

By completely blocking the bore208between the upstream bore portion208-1and the downstream bore portion208-2, and by making full face-to-face contact with all of the inner surface251of the seat220and with all of the inner surface351of the seat320, the gate215stops flow of the fluid288from the upstream bore portion208-1to the downstream bore portion208-2. This generates a pressure differential across the gate215so that the pressure within the upstream bore portion208-1is higher than the pressure within the downstream bore portion208-2. In addition, the force of the fluid288against the gate215within the upstream bore portion208-1can increase the force between the gate215and the inner surface351of the seat320while also decreasing the force between the gate215and the inner surface251of the seat220.

In such cases, the sealing members225of the seat220and the sealing members325of the seat320can compensate and help to keep the fluid288from escaping from the upstream bore portion208-1within the gate valve200. As discussed above, designs of sealing members225and/or sealing members325can incorporate a seal on the seat pocket side and a spring. The spring can either be incorporated into the seal or separate. The spring can provide some force to create contact pressure between the seat (e.g., seat220, seat320) and the gate215for low pressure performance. However, this type of design struggles at low pressure (e.g., less than 10% of RWP) as the contact pressure interface is limited based on full differential requirements.

If the contact area between the gate215and the inner surface351of the seat320and/or the inner surface251of the seat220is too small, the sealing members (e.g., sealing members225, sealing members325) yield during high pressure (e.g., above 10% of RWP). The large contact area between the gate215and the inner surface351of the seat320and/or the inner surface251of the seat220requires more spring to get the contact pressure to seal at low pressure. However, using such a large spring makes the torque and installation load too high. The industry standard API 6A for gate valves requires 10% of RWP as an acceptable low-pressure limit. This means a gate valve rated at 15000 psi often fails below 1500 psi. Real world conditions for field operations in many cases is low pressure (e.g., less than 10% of RWP) for the majority of the life a gate valve, with high pressure being only in contingency that occurs in relatively rare circumstances. In other words, gate valves operating at low pressure is most typical the majority of the time. As a result, the design of seats of gate valves in the current art are not optimized for actual field conditions, which leads to drawbacks that include, but are not limited to, high equipment failure, high valve change out frequency, increased cost, increased risk, and increased emissions. Example seats for gate valves reduces or eliminates these problems by providing dramatically improved performance at relatively low pressure conditions.

FIGS.4A and4Bare graphs that show the relationship between contact pressure and bore pressure for a gate valve according to the current art. Specifically,FIG.4Ashows a graph498that includes a plot497of contact pressure (shown on the vertical axis in kpsia) and pressure (shown on the horizontal axis in kpsia) within the bore (e.g., bore108) of a gate valve (e.g., gate valve100).FIG.4Bshows a detailed view of the plot497of the graph498ofFIG.4Afor bore pressures below 1 kpsia. Referring toFIGS.1through4B, the contact pressure in this case is between the inner surface (e.g., inner surface151-2) of a seat (e.g., seat120-2) and the adjacent wall of the valve body (e.g., valve body102). Also, the bore pressure is the differential pressure between the upstream bore portion (e.g., upstream bore portion208-1) and the downstream bore portion (e.g., downstream bore portion208-2).

The plot497of the graph498shows that the relationship between contact pressure and bore pressure is substantially linear when the bore pressure is above approximately 1000 psia. As shown by the detail graph inFIG.4B, the plot497loses its linearity when the bore pressure is below approximately 1000 psia. If the gate valve in this example has a RWP of 10 kpsia, the plot497indicates that the gate valve can have performance problems when the bore pressure is at or less than 10% of the RWP. Specifically, at relatively lower bore pressures, the contact pressure needs to be multiples greater than the bore pressure to avoid failure of the gate valve. This reiterates the point made above that the design currently used in the art in terms of the interaction between the seat and the valve wall at relatively low pressure conditions leads to frequent problems.

FIGS.5A through13shows various embodiments of an example seat according to certain example embodiments. Specifically,FIGS.5A and5Bshow a sectional side view and a detailed view, respectively, of an example of a seat520for a gate valve according to certain example embodiments.FIG.6shows a sectional side view of another example of a seat620for a gate valve according to certain example embodiments.FIG.7shows a sectional side view of yet another example of a seat720for a gate valve according to certain example embodiments.FIGS.8through13show front views of various example seats according to certain example embodiments.

Referring toFIGS.1through13, the example seats discussed herein have multiple variations of a spring system having two general features. The first feature of the spring system is an outward protrusion (part of a spring section herein) of part of the inner surface of the seat. The protrusion can be tapered relative to the inner surface of the seat. The second feature of the spring system is a cavity within the seat body of the seat, where the cavity and the outward protrusion are positioned relatively close to each other. Under such an arrangement, the outward protrusion makes first contact with the gate of the gate valve relative to a remainder of the inner surface of the seat.

When the gate contacts the outward protrusion, the gate applies an inward force against the outward protrusion. In other words, the protrusion creates an initial interference with the gate as the gate, in a closed position, has increased pressure applied to it from the upstream side of the bore. As the differential pressure increases and the gate is pushed with more force toward the downstream side of the bore, the gate comes into more and more contact with the seat. Because the cavity within the seat body is proximate to the outward protrusion, the outward protrusion acts as a type of spring and causes the size of the cavity to shrink as the gate pushes the outward protrusion toward the outer surface of the seat. This arrangement results in a significantly higher contact pressure between the inner surface of the seat and the adjacent wall of the valve body when the core pressure is at a level (e.g., 10% of RWP) commonly found during operations.

The position of each example seat within a gate valve relative to a seat currently used in the art is unchanged. Also, the footprint (e.g., shape, size) of each example seat is substantially the same as the footprint of a seat currently used in the art. As such, example seats can be used to replace existing seats to retrofit existing gate valves without having to make any other modifications to the existing gate valves.

For example, the seat520ofFIGS.5A and5Bincludes a seat body521that generally has a rectangular cross-sectional shape with a height567and a width (thickness)568. Overall, the seat body521of the seat520can be cylindrical in shape. The seat body521has an inner surface551and an outer surface552. The outer surface552can optionally include one or more sealing members525, which are substantially the same as the sealing members125, the sealing members225, and the sealing members325discussed above. In this case, there are two sealing members525, where the sealing member525-1is positioned toward the outer perimeter556of the seat body521, and where the sealing member525-2is positioned toward the inner perimeter557of the seat body521. The sealing members525are configured to interact with a wall of the valve body (e.g., valve body202).

The seat520can have one or more spring systems540. In this example, the seat520has a single spring system540. As shown inFIGS.5A and5B, the spring system540includes one or more cavities545and a spring section547. A cavity545is disposed in the seat body521. A cavity545can have any of a number of characteristics (e.g., height561, width562, length, shape). For example, a cavity545can be slightly conically shaped. A cavity545can have an open end, as in this case where the cavity545-1and the cavity545-N have an open bottom end. Alternatively, a cavity545can be completely enclosed within the seat body521. When the seat520has multiple cavities545, the characteristics (e.g., height, width, shape, fluid or material used as filler) of one cavity545can be the same as, or different than, one or more of the corresponding characteristics of one or more of the other cavities545.

In some cases, a cavity545can be filled, in whole or in part, with a fluid (e.g., air) and/or some other material (e.g., an elastomeric material, a gel). In such cases, the fluid and/or other material that fills some or all of the cavity545can be configured to allow the shape of the cavity545to change when a force is applied to the spring section547in the direction of the outer surface552of the seat body521. In some cases, a cavity545has a height561that is greater than the height of the spring section547. A cavity545can be formed within the seat body521in any of a number of ways, including but not limited to drilling and casting.

A spring section547of a spring system540is positioned between a cavity545and the inner surface551of the seat body521toward the inner perimeter557of the seat body521. A spring section547can include a base portion542of the seat body521that falls within an extension of the plane formed by the inner surface551of the seat body521and a protrusion544that extends outward from the plane formed by the inner surface551of the seat body521. The base portion542(or portions thereof) and the protrusion544(or portions thereof) of the spring section547can be separate pieces that are coupled to each other (e.g., using epoxy, using independent coupling features). In addition, or in the alternative, the base portion542(or portions thereof) and the protrusion544(or portions thereof) of the spring section547can be integral with each other, formed from a continuous piece.

In certain example embodiments, the spring section547is configured to move inward (i.e., toward the cavity545) and reduce the volume of the cavity545when an inward force is applied to the spring section547. This situation can occur when a gate (e.g., gate115, gate215) contacts the spring section547, regardless of whether the gate is stationary or moving to change the position (e.g., from open to closed) of the gate valve (e.g., gate valve100, gate valve200). In such cases, the cavity545of the spring system540is designed to provide some amount of interference along a range of core pressures, which translates to forces applied by the gate to the seat520.

When the gate no longer contacts the spring section547of the spring system540, the spring section547is configured to revert to its default position, thereby allowing the volume of the cavity545to be restored. Because the gate contacts at least a majority of the inner surface551of the seat520at all times during operation of the gate valve, the example spring system540is capable of being engaged at all times. When the core pressure is relatively low (e.g., less than 10% of the RWP of the gate valve), the example spring system540dramatically increases the contact pressure relative to the current art, as shown below with respect toFIG.16. The spring system540can be designed to have a substantially fixed contact pressure up to a certain bore pressure, which is also shown below with respect toFIG.16.

The protrusion544of the spring section547can have any of a number of characteristics (e.g., shape, length, width, height, material). For example, the protrusion544can be a single continuous piece that is placed over and epoxied to part of the inner surface551of the seat body521. As another example, the cross-sectional shape (as shown inFIG.5B) of the protrusion544can be a triangle. In alternative embodiments, the cross-sectional shape of the distal part of the protrusion544can be curved (e.g., concave, convex, parabolic, elliptical) and/or some other shape aside from linear. The protrusion544can be a segmented piece that covers only a portion of the length and width of the inner surface551of the seat body521.

In this case, the outer surface of the protrusion544is tapered relative to the inner surface551of the seat520and creates an acute angle543(e.g., no greater than) 15° with the inner surface551of the seat body521. In alternative embodiments, rather than being tapered, the protrusion544can have any of a number of other shapes (e.g., a curvature) and/or features (e.g., a textured surface). The protrusion544can have a vertical height563and a maximum width564. The vertical height563of the protrusion544can be less than the height561of the adjacent cavity545-1of the spring system540. The protrusion544can include one or more sealing members549. In this example, a sealing member549is disposed in a channel along the outer surface of the protrusion544. The sealing member549can be substantially the same as the sealing members125and the sealing members225discussed above.

In certain example embodiments, the spring section547of the spring system540can include one or more optional keys548that can be used to properly align the seat520within the gate valve. In such cases, the key548can interact with a tool or other device used by a user to properly manipulate and position the seat520within the gate valve. In addition, or in the alternative, the key548can interact with a complementary feature of another component of the gate valve. The key548can take on any of a number of forms, including but not limited to a notch, a detent, a protrusion, an aperture, a recess, a tab, and a slot. In some cases, a key548can additionally or alternatively be disposed on a different part of the seat body521of the seat520.

Referring toFIG.6, the seat620includes a seat body621having an inner surface651, an outer surface652, an inner perimeter657, and an outer perimeter656. There are two sealing members625, where the sealing member625-1is positioned toward the outer perimeter656of the seat body521along the outer surface652, and where the sealing member625-2is positioned toward the inner perimeter657along the outer surface652of the seat body621. The sealing members625are configured to interact with a wall of the valve body (e.g., valve body202) and are substantially similar to the sealing members discussed above.

The seat620also includes a spring system640that includes a cavity645and a spring section647. The cavity645in this case is completely enclosed within the seat body621. The spring section647includes a base portion642and a protrusion644that extends outward from the plane of the inner surface651in a manner similar to the configuration of the protrusion644ofFIGS.5A and5B. There is also a sealing member649, similar to the sealing member549discussed above, disposed in the protrusion644of the spring section647.

Referring toFIG.7, the seat720includes a seat body721having an inner surface751, an outer surface752, an inner perimeter757, and an outer perimeter756. There are two sealing members725, where the sealing member725-1is positioned toward the outer perimeter756of the seat body721along the outer surface752, and where the sealing member725-2is positioned toward the inner perimeter757along the outer surface752of the seat body721. The sealing members725are configured to interact with a wall of the valve body (e.g., valve body202) and are substantially similar to the sealing members discussed above.

The seat720also includes a spring system740that includes a cavity745and a spring section747. In this case, the spring system740is a separate component that is coupled to the seat body721. The body765of the spring system740can be made of the same or a different material compared to the material of the seat body721. The cavity745in this case is disposed in the body765of the spring system740and has an open-ended bottom. The spring section747includes a base portion742and a protrusion744that extends outward from the plane of the inner surface751of the seat body721in a manner similar to the configuration of the protrusion544ofFIGS.5A and5B. There is also a sealing member749, similar to the sealing member549discussed above, disposed in the protrusion744of the spring section747.

Referring toFIG.8, the front view of the seat820shows the inner surface851, the inner perimeter857, and the outer perimeter856. Also shown inFIG.8is the protrusion844of the spring section847of the spring system840. In this case, the protrusion844is ring-shaped and is positioned coincident with the inner perimeter857of the seat body821. The cavity (e.g., similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring system840is hidden from view inFIG.8, but can have any of a number of configurations. For example, the cavity can be a slot in the inner perimeter857of the seat body821having a depth that is greater than the height of the protrusion844.

Referring toFIG.9, the front view of the seat920shows the inner surface951, the inner perimeter957, and the outer perimeter956. Also shown inFIG.9is the protrusion944-1of the spring section947-1of the spring system940-1, as well as the protrusion944-2of the spring section947-2of the spring system940-2. In this case, the protrusion944-1is ring-shaped and is positioned coincident with the inner perimeter957of the seat body921, and the protrusion944-2is also ring-shaped and is positioned coincident with the outer perimeter956of the seat body921. The two cavities (e.g., each similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring systems940is hidden from view inFIG.9, but can have any of a number of configurations. For example, the cavity of the spring system940-1can be a slot in the inner perimeter957of the seat body921having a depth that is greater than the height of the protrusion944-1, and the cavity of the spring system940-2can be a slot in the outer surface of the seat body921having a depth that is greater than the height of the protrusion944-2.

Referring toFIG.10, the front view of the seat1020shows the inner surface1051, the inner perimeter1057, and the outer perimeter1056. Also shown inFIG.10is the protrusion1044of the spring section1047of the spring system1040. In this case, the protrusion1044is an arc segment that is positioned coincident with approximately the bottom quarter of the inner perimeter1057of the seat body1021. The cavity (e.g., similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring system1040is hidden from view inFIG.10, but can have any of a number of configurations. For example, the cavity can be a fully enclosed pocket within the seat body1021positioned behind and above the protrusion1044.

Referring toFIG.11, the front view of the seat1120shows the inner surface1151, the inner perimeter1157, and the outer perimeter1156. Also shown inFIG.11is the protrusion1144-1of the spring section1147-1of the spring system1140-1, the protrusion1144-2of the spring section1147-2of the spring system1140-2, the protrusion1144-3of the spring section1147-3of the spring system1140-3, and the protrusion1144-4of the spring section1147-4of the spring system1140-4. In this case, the four protrusions1144are arc segments that are positioned equidistantly from each other along the inner perimeter1157of the seat body1121. The four cavities (e.g., similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring systems1140are hidden from view inFIG.11, but can have any of a number of configurations. For example, each cavity can be a slot in the inner perimeter1157of the seat body1121having a depth and a width that are greater than the height and width of each corresponding protrusion1144of the spring system1140.

Referring toFIG.12, the front view of the seat1220shows the inner surface1251, the inner perimeter1257, and the outer perimeter1256. Also shown inFIG.12is the protrusion1244-1of the spring section1247-1of the spring system1240-1, the protrusion1244-2of the spring section1247-2of the spring system1240-2, the protrusion1244-3of the spring section1247-3of the spring system1240-3, and the protrusion1244-4of the spring section1247-4of the spring system1240-4. In this case, the four protrusions1244are semi-circular protrusions that are positioned equidistantly from each other, each running radially from the inner perimeter1257to the outer perimeter1256of the seat body1221. The four cavities (e.g., similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring systems1240are hidden from view inFIG.12, but can have any of a number of configurations. For example, each cavity can be a slot running behind the protrusion1244between the outer perimeter1256and the inner perimeter1257within the seat body1221having a width that is greater than the width of each corresponding protrusion1244of the spring system1240.

Referring toFIG.13, the front view of the seat1320shows the inner surface1351, the inner perimeter1357, and the outer perimeter1356. Also shown inFIG.13is the protrusion1344-1of the spring section1347-1of the spring system1340-1, the protrusion1344-2of the spring section1347-2of the spring system1340-2, the protrusion1344-3of the spring section1347-3of the spring system1340-3, the protrusion1344-4of the spring section1347-4of the spring system1340-4, the protrusion1344-5of the spring section1347-5of the spring system1340-5, and the protrusion1344-6of the spring section1347-6of the spring system1340-6. In this case, protrusion1344-1, protrusion1344-2, and protrusion1344-3are arc segments that are positioned equidistantly from each other along the outer perimeter1356of the seat body1321, and protrusion1344-4, protrusion1344-5, and protrusion1344-6are arc segments that are positioned equidistantly from each other along the inner perimeter1357of the seat body1321.

The six cavities (e.g., similar to the cavity545discussed above with respect toFIGS.5A and5B) of the spring systems1340are hidden from view inFIG.13, but can have any of a number of configurations. For example, each cavity of the spring system1340-1, the spring system1340-2, and the spring system1340-3can be a slot in the outer perimeter1356of the seat body1321having a depth and a width that are greater than the height and width of each corresponding protrusion1344of the spring system1340. Similarly, each cavity of the spring system1340-4, the spring system1340-5, and the spring system1340-6can be a slot in the inner perimeter1357of the seat body1321having a depth and a width that are greater than the height and width of each corresponding protrusion1344of the spring system1340.

FIG.14shows a sectional view of part of a gate valve1400with the gate1415in the open position according to certain example embodiments.FIG.15shows a sectional view of part of the gate valve1400ofFIG.14with the gate1415in the closed position according to certain example embodiments. Referring toFIGS.1through15, the gate valve1400ofFIGS.14and15includes a valve body1402, a bore1408, a valve trim1410, and two example seats (seat1420and seat1520). These components of the gate valve1400, including portions thereof, can be substantially the same as the valve bodies, the bores, the valve trims, and the example seats (including corresponding portions thereof) discussed above. For example, the valve body1402can form a proximal receiving area1413and a distal receiving area1411for the gate1415and/or other parts of the valve trim1410.

The seat1420surrounds the bore portion108-2of the bore108and is positioned between the gate1415and the valve body1402. The seat1420is configured similar to the seat920ofFIG.9. Specifically, the seat1420includes a spring system1440-1and a spring system1440-2. The spring system1440-1is located along the inner surface1451toward the inner perimeter1467, and the spring system1440-2is located along the inner surface1451toward the outer perimeter1466. The spring system1440-1includes a cavity1451-1and a spring section1447-1that includes a base portion1442-1and a protrusion1444-1. The spring system1440-2includes a cavity1451-2and a spring section1447-2that includes a base portion1442-2and a protrusion1444-2.

Also, the seat1520is configured similar to the seat920ofFIG.9. Specifically, the seat1520includes a spring system1540-1and a spring system1540-2. The spring system1540-1is located along the inner surface1551toward the inner perimeter1567, and the spring system1540-2is located along the inner surface1551toward the outer perimeter1566. The spring system1540-1includes a cavity1551-1and a spring section1547-1that includes a base portion1542-1and a protrusion1544-1. The spring system1540-2includes a cavity1551-2and a spring section1547-2that includes a base portion1542-2and a protrusion1544-2.

When the gate1415is in the open position, as shown inFIG.14, the hole1416in the gate1415is aligned with the bore1408, thereby allowing a fluid1488to flow from the upstream bore portion1408-1of the bore1408, through the hole1416in the gate1415, and through the downstream bore portion1408-2of the bore1408. Also, the gate1415, when in the open position, abuts against and engages all of the extension1444-1of the spring section1447-1of the seat1420and all of the extension1544-1of the spring section1547-1of the seat1520, which compresses the cavity1445-1and the cavity1545-1, respectively. When in the open position, the gate1415also abuts against and engages the extension1444-2except for the portion on the lower ⅛th of the seat body1421and the extension1544-2except for the portion on the lower ⅛th of the seat body1521, which compresses the cavity1445-2except for the portion on the lower ⅛th of the seat body1421and the cavity1545-2except for the portion on the lower ⅛th of the seat body1521, respectively.

Under this operating condition, the configuration of the example seat1420and the example seat1520result in a substantially higher contact pressure relative to the current art when the bore pressure is relatively low (e.g., less than 10% of the RWP). When the gate1415closes, as shown inFIG.15, the gate1415above the hole1416completely covers the bore1408, and also makes full contact with all of the inner surface1451of the seat1420and with all of the inner surface1551of the seat1520. As a result, the gate1415, when in the closed position, abuts against and engages all of the extension1444-1of the spring section1447-1of the seat1420, all of the extension1444-2of the spring section1447-2of the seat1420, all of the extension1544-1of the spring section1547-1of the seat1520, and all of the extension1544-2of the spring section1547-2of the seat1520, which compresses the cavity1445-1, the cavity1445-2, the cavity1545-1, and the cavity1545-2, respectively. Also, the closed gate1415keeps the fluid1488from flowing from the bore portion1408-1into the bore portion1408-2.

FIG.16shows a graph1698of contact pressure versus bore pressure for a gate valve according to certain example embodiments. Specifically, the graph1698ofFIG.16shows data plotted using the gate valve1400ofFIGS.14and15. Referring toFIGS.1through16, the graph1698ofFIG.16includes the plot497of contact pressure (shown on the vertical axis in kpsia) and pressure (shown on the horizontal axis in kpsia) within the bore (e.g., bore108) of a gate valve (e.g., gate valve100) from the graph498ofFIGS.4A and4B. Using the example seats (in this case, seat1420and seat1520), at lower core pressures of approximately less than 2600 psia, plot1696shows that the contact pressure is substantially constant at 6500 psia. In this way, the seat1420maintains a contact pressure with the gate1415that is at least twice a pressure within the bore1408between the gate1415and the inlet when the bore pressure is within 10% of RWP of the gate valve1400. These contact pressure values are significantly higher than what is realized using seats in the current art. As a result, failures of the gate valve1400at these lower pressures, which constitute the vast majority of the operating pressure for the gate valve1400, are eliminated or significantly reduced.

FIGS.17A and17Bshow another example of a seat1720for a gate valve according to certain example embodiments. Specifically,FIG.17Ashows a sectional view of the seat1720in a consolidated position, andFIG.17Bshows a sectional view of the seat1720in an expanded position. Referring toFIGS.1through17B, the seat1720can include any of a number of multiple (e.g., two, three, five) pieces, where adjacent pieces are configured to be movably coupled to each other. In this case, the seat1720has two pieces1729(piece1729-1and piece1729-2). In such cases, each piece1729of the seat1720includes a seat body1721having one or more inner surfaces1751, one or more outer surfaces1752, one or more inner perimeters1757, and one or more outer perimeters1756.

Piece1729-1of the seat1720ofFIGS.17A and17Bgenerally has a “L” shape and has a body1721-1with one outer surface1752-1, one inner perimeter1757-1, two inner surfaces1751-1(with inner surface1751-1A being further away from the outer surface1752-1relative to the inner surface1751-1B and adjacent to the inner perimeter1757-1), and two outer perimeters1756(with the outer perimeter1756-1A positioned between the outer surface1752-1and the inner surface1751-1B and with the outer perimeter1756-1B positioned between the inner surface1751-1A and the inner surface1751-1B).

The piece1729-1can include one or more coupling features1792-1that allow the piece1729-1to be movably coupled, directly or indirectly, to the piece1729-2. For example, in this case, a coupling feature1792-1in the form of mating threads is disposed on part of the outer perimeter1756-1B to allow the piece1729-1to be directly movably coupled to the piece1729-2. The one or more coupling features1792-1of the piece1729-1are configured to complement one or more coupling features1792-2of the piece1729-2of the seat1720.

There are four sealing members1725disposed on the piece1729-1of the seat1720. Sealing member1725-1is positioned toward the outer perimeter1756-1A of the seat body1721-1along the outer surface1752-1. Sealing member1725-2is positioned toward the inner perimeter1757-1along the outer surface1752-1of the seat body1721-1. The sealing member1725-1and the sealing member1725-2are configured to interact with a wall of the valve body (e.g., valve body1402) and are substantially similar to the sealing members discussed above.

Sealing member1725-3is positioned toward the inner surface1751-1B along the outer perimeter1756-1B of the seat body1721-1. The sealing member1725-3is configured to interact with the inner perimeter1757-2B of the piece1729-2of the seat1720and is substantially similar to the sealing members discussed above. Sealing member1725-4is positioned toward the inner perimeter1757-1along the inner surface1751-1A of the seat body1721-1. The sealing member1725-4is configured to interact with the outer surface1752-2A of the piece1729-2of the seat1720, particularly when the seat1720is in the consolidated position shown inFIG.17A, and is substantially similar to the sealing members discussed above.

The piece1729-1of the seat1720does not include the spring system1740, except that when the seat1720is in the expanded position shown inFIG.17B, the inner surface1751-1A of the piece1729-1forms part of the cavity1745. In certain example embodiments, the piece1729-1can include one or more optional keys1748that can be used to properly align the piece1729-1of the seat1720within the gate valve (e.g., gate valve1400). In such cases, the key1748can be substantially the same and serve the same functions as the key548discussed above. In this example, the piece1729-1is in the form of a notch and is located along the inner perimeter1757-1of the piece1729-1.

Piece1729-2of the seat1720ofFIGS.17A and17Bgenerally has an inverted backwards “L” shape and has a body1721-2with two outer surfaces1752-2(with outer surface1752-2B being further away from the inner surface1751-2relative to the outer surface1752-2A and adjacent to the outer perimeter1756-2), two inner perimeters1757-2(with the inner perimeter1757-2A positioned between the outer surface1752-2A and the inner surface1751-2and with the inner perimeter1757-2B positioned between the outer surface1752-2A and the outer surface1752-2B), one inner surface1751-2, and one outer perimeter1756.

The piece1729-2can include one or more coupling features1792-2that allow the piece1729-2to be movably coupled, directly or indirectly, to the piece1729-1. For example, in this case, a coupling feature1792-2in the form of mating threads is disposed on part of the inner perimeter1757-2B to allow the piece1729-2to be directly movably coupled to the piece1729-1. The one or more coupling features1792-2of the piece1729-2are configured to complement one or more coupling features1792-1of the piece1729-1of the seat1720.

The piece1729-2of the seat1720also includes a spring system1740that includes a spring section1747. The cavity1745of the spring system1740in this case is located between the inner surface1751-1A of the piece1729-1, the inner perimeter1757-2B of the piece1729-2, and the outer surface1752-2A of the piece1729-2when the seat1720is in the expanded position shown inFIG.17B. When the seat1720is in the consolidated position, as shown inFIG.17A, the cavity1745is non-existent (if the inner surface1751-1A of the piece1729-1and the outer surface1752-2A of the piece1729-2are in direct contact with each other) or minimal (e.g., if the sealing member1725-4provides a slight gap between the inner surface1751-1A of the piece1729-1and the outer surface1752-2A of the piece1729-2). As the piece1729-2and the piece1729-1move apart from each other using the coupling features1792, the size of the cavity1745increases.

The spring section1747includes a base portion1742and a protrusion1744that extends outward from the plane of the inner surface1751-2of the piece1729-2in a manner similar to the configuration of the protrusion544ofFIGS.5A and5B. There is also a sealing member1749, similar to the sealing member549discussed above, disposed in the protrusion1744of the spring section1747. The piece1729-2can also include one or more optional keys1748that can be used to properly align the piece1729-2of the seat1720within the gate valve (e.g., gate valve1400). In such cases, the key1748can be substantially the same and serve the same functions as the key548discussed above. In this example, the piece1729-2is in the form of a notch and is located along the inner perimeter1757-2A of the piece1729-2.

In certain example embodiments, the piece1729-2(or portions thereof) of the seat1720is made of a material that has a high hardness (e.g., tungsten carbide) and/or other characteristics relative to the material (e.g., 410 stainless steel) of the piece1729-1(or portions thereof) of the seat1720. In some cases, splitting the hard materials for the piece1729-2and the soft materials for the piece1729-1can be done without requiring thermal application. Using relatively softer materials for the piece1729-1, which is larger than the piece1729-2, can result in using less expensive material that is relatively easier to machine compared to the hard material of the piece1729-2and, in many cases, the single piece seats commonly used today.

When the seat1720is installed into a gate valve (e.g., gate valve1400), the seat1720can be in a consolidated position, as shown inFIG.17A. In this state, the seat1720has a height1767and a width (thickness)1768-1. In this consolidated position, in certain example embodiments, no part of the seat1720, including the protrusion1744of the spring section1747, makes contact with the gate (e.g., gate1415) of the gate valve, regardless of the position of the gate. In other cases, any contact between the protrusion1744of the spring section1747and the gate when the seat1720is in the consolidated position is minimal.

When the gate valve is completely assembled, the pieces1729of the seat1720can be separated from each other using the coupling features1792, putting the seat1720in the expanded position shown inFIG.17B. In this state, the seat1720has a height1767and a width (thickness)1768-2that is greater than the width1768-1. This can be accomplished, for example, using a tool to rotate the piece1729-2of the seat1720relative to the piece1729-1to a fixed torque. The torque can correlate to an initial spring condition of the spring section1747of the spring system1740. In this way, tolerancing, which can be difficult to achieve with a seat1720configured as a single piece (e.g., by pulling in a spring), can be properly set more easily.

FIGS.18A and18Bshow yet another example of a seat1820for a gate valve according to certain example embodiments. Specifically,FIG.18Ashows a sectional view of the seat1820, andFIG.18Bshows a detailed view of the seat1820ofFIG.18A. Referring toFIGS.1through18B, the seat1820can include any of a number of multiple (e.g., two, three, five) pieces, where adjacent pieces are configured to be movably coupled to each other. In this case, the seat1820has three pieces1829(piece1829-1, piece1829-2, and piece1829-3) arranged in a telescoping fashion. In such cases, each piece1829of the seat1820includes a seat body1821having one or more inner surfaces1851, one or more outer surfaces1852, one or more inner perimeters1857, and one or more outer perimeters1856.

Piece1829-1of the seat1820ofFIGS.18A and18Bis the largest of the 3 pieces1829. The piece1829-1has a generally rectangular cross-sectional shape, except for a portion carved out of its inner surface1851and its inner perimeter1857. The piece1829-1has a body1821-1with one outer surface1852-1, one outer perimeter1856-1, three inner surfaces1851-1(with inner surface1851-1A being further away from the outer surface1852-1relative to the inner surface1851-1B, and with the inner surface1851-1B being further away from the outer surface1852-1relative to the inner surface1851-1C, and with the inner surface1851-1C being adjacent to the inner perimeter1857-1C), and three inner perimeters1857(with the inner perimeter1857-1A positioned between the inner surface1851-1B and the inner surface1851-1A, with the inner perimeter1857-1B positioned between the inner surface1851-1B and the inner surface1851-1C, and with the inner perimeter1857-1C positioned between the outer surface1852-1and the inner surface1851-1C).

There are two sealing members1825disposed on each of the pieces1829of the seat1820. Sealing member1825-1is positioned toward the outer perimeter1856-1of the seat body1821-1along the outer surface1852-1. Sealing member1825-2is positioned toward the inner perimeter1857-1C along the outer surface1852-1of the seat body1821-1. The sealing member1825-1and the sealing member1825-2are configured to interact with a wall of the valve body (e.g., valve body1402) and are substantially similar to the sealing members discussed above.

Sealing member1825-3and sealing member1825-4are disposed adjacent to each other along the outer perimeter1856-3A of the seat body1821-3, with sealing member1825-4being positioned slightly closer to the inner surface1851-3and with sealing member1825-3being positioned slightly closer to the outer surface1852-3A. The sealing member1825-3and the sealing member1825-4are configured to interact with the inner perimeter1857-2A of the piece1829-2of the seat1820and are substantially similar to the sealing members discussed above.

Sealing member1825-5and sealing member1825-6are disposed adjacent to each other along the outer perimeter1856-2A of the seat body1821-2, with sealing member1825-6being positioned slightly closer to the inner surface1851-2A and with sealing member1825-5being positioned slightly closer to the outer surface1852-2A. The sealing member1825-5and the sealing member1825-6are configured to interact with the inner perimeter1857-1A of the piece1829-1of the seat1820and are substantially similar to the sealing members discussed above.

The piece1829-1of the seat1820may not itself include the spring system1840-1, but piece1829-1shares part of a spring system1840-2with the piece1829-2by virtue of the inner surface1851-1B of the piece1829-1forms part of the cavity1845-2inside of which one or more resilient devices1838-2(e.g., a Belleville spring) are disposed. All but the bottom of the inner surface1851-1A in this case has a large negative slope. In alternative embodiments, the inner surface1851-1A can be vertical. In alternative embodiments, the piece1829-1can include a spring system1840-1with a spring section1847-3having a base portion1842-3and a protrusion1844-3that extends outward to form the inner surface1851-1A of the piece1829-1. In such cases, there can be one or more apertures (e.g., similar to the apertures1445discussed above), located proximate to the protrusion1844-3, in the body1821-1of the piece1829-1. In this case, the protrusion1844-3(and so also the bottom of the inner surface1851-1A) are substantially vertical. In alternative embodiments, the bottom of the inner surface1851-1A can have a large negative slope, as with the rest of the inner surface1851-1A. In this case, the piece1829-1does not include any features (e.g., the keys1748discussed above) that can be used to align the piece1829-1and the piece1829-2of the seat1820relative to each other.

Piece1829-2of the seat1820ofFIGS.18A and18Bgenerally has a rectangular cross-sectional shape with a lateral extension from the bottom of its outer surface1852-2B. The piece1829-2has a body1821-2with two outer surfaces1852-2(with outer surface1852-2B being further away from any of the three the inner surfaces1851-2relative to the outer surface1852-2A, where the outer surface1852-2B is adjacent to the outer perimeter1856-2B, and where the outer surface1852-2B forms part of the cavity1845-2of the spring system1840-2), three inner perimeters1857-2(with the inner perimeter1857-2A positioned between the inner surface1851-2A and the inner surface1851-2B, with the inner perimeter1857-2B positioned between the inner surface1851-2B and the inner surface1851-2C, and with inner perimeter1857-2C positioned between the inner surface1851-2C and the outer surface1852-2B), three inner surfaces1851-2(with the inner surface1851-2A positioned between the outer perimeter1856-2A and the inner perimeter1857-2A, with the inner surface1851-2B positioned between the inner perimeter1857-2A and the inner perimeter1857-2B, and with the inner surface1851-2C positioned between the inner perimeter1857-2B and the inner perimeter1857-2C), and two outer perimeters1856-2(with the outer perimeter1856-2A positioned between the inner surface1851-2A and the outer surface1852-2A, and with the outer perimeter1856-2B positioned between the outer surface1852-2A and the outer surface1852-2B).

The piece1829-2of the seat1820also includes a spring system1840-2, which is partly shared with the piece1829-1as discussed above, and shares part of another spring system1840-1with the piece1829-3. The spring system1840-2includes a spring section1847-2. The cavity1845-2of the spring system1840-2in this case is located between the inner surface1851-1B of the piece1829-1, the inner perimeter1857-1A of the piece1829-1, the outer surface1852-2B of the piece1829-2, and the outer perimeter1856-2B of the piece1829-2, regardless of whether the seat1820is in the expanded position (as shown inFIGS.18A and18B), a partially consolidated position (as shown inFIG.19Abelow), or a fully consolidated position (as shown inFIG.19Bbelow).

When the seat1820is in the expanded position, as shown inFIGS.18A and18B, the cavity1845-2has a width1819-2, which shrinks as the seat1820moves to a partially or fully consolidated position, as shown inFIGS.19A and19Bbelow. Because of the resilient device1838-2within the cavity1845-2and/or because the maximum width1869-2of the gap1839-2is less than the maximum width1819-2of the cavity1845-2, the width1819-2of the cavity1845-2does not reach zero.

The spring section1847-2includes a base portion1842-2and a protrusion1844-2that extends outward to form the inner surface1851-2A of the piece1829-2. In this case, the protrusion1844-2(and so also the inner surface1851-2A) are substantially vertical. In alternative embodiments, the inner surface1851-2A can have a large negative slope. In this case, the spring section1847-2does not have any sealing members or keys, such as what is discussed above. The piece1829-2(or portions thereof) of the seat1820can be made of or include the same or a different material relative to the one or more materials of the piece1829-1(or portions thereof) of the seat1820.

The default position of the piece1829-2relative to the piece1829-1is in an expanded position, as shown inFIGS.18A and18B. In this state, the cavity1845-2has a width1819-2, and the gap1839-2between the inner surface1851-1C of the body1821-1of the piece1829-1and the outer surface1852-2B of the body1821-2of the piece1829-2has a width1869-2. The width1819-2of the cavity1845-2can be the same as, or different than, the width1869-2of the gap1839-2. Also, the inner surface1851-2A of the piece1829-2extends inward by a distance1859-2relative to the inner surface1851-1A of the piece1829-1when the seat1820is in the default (expanded) position.

Piece1829-3of the seat1820ofFIGS.18A and18Bgenerally has a rectangular cross-sectional shape with a lateral extension from the bottom of its outer surface1852-3B. The piece1829-3has a body1821-3with two outer surfaces1852-3(with outer surface1852-3B being further away from any of the three the inner surfaces1851-3relative to the outer surface1852-3A, where the outer surface1852-3B is adjacent to the outer perimeter1856-3B, and where the outer surface1852-3B forms part of the cavity1845-1of the spring system1840-1), one inner perimeter1857-3, one inner surface1851-3, and two outer perimeters1856-2(with the outer perimeter1856-3A positioned between the inner surface1851-3and the outer surface1852-3A, and with the outer perimeter1856-3B positioned between the outer surface1852-3A and the outer surface1852-3B).

The piece1829-3of the seat1820also includes a spring system1840-1, which is partly shared with the piece1829-2, as discussed above. The spring system1840-1includes a spring section1847-1. The cavity1845-1of the spring system1840-1in this case is located between the inner surface1851-2B of the piece1829-2, the inner perimeter1857-2A of the piece1829-2, the outer surface1852-3B of the piece1829-3, and the outer perimeter1856-3B of the piece1829-3, regardless of whether the seat1820is in the expanded position (as shown inFIGS.18A and18B), a partially consolidated position (as shown inFIG.19Abelow), or a fully consolidated position (as shown inFIG.19Bbelow).

When the seat1820is in the expanded position, as shown inFIGS.18A and18B, the cavity1845-1has a width1819-1, which shrinks as the seat1820moves to a partially or fully consolidated position, as shown inFIGS.19A and19Bbelow. Because of the resilient device1838-1within the cavity1845-1and/or because the maximum width1869-1of the gap1839-1is less than the maximum width1819-1of the cavity1845-1, the width1819-1of the cavity1845-1does not reach zero.

The spring section1847-1includes a base portion1842-1and a protrusion1844-1that extends outward to form the inner surface1851-3of the piece1829-3. In this case, the protrusion1844-1(and so also the inner surface1851-3) are substantially vertical. In alternative embodiments, the inner surface1851-3can have a large negative slope. In this case, the spring section1847-1does not have any sealing members or keys, such as what is discussed above. The piece1829-3(or portions thereof) of the seat1820can be made of or include the same or a different material relative to the one or more materials of the piece1829-1(or portions thereof) and/or the piece1829-2(or portions thereof) of the seat1820.

The default position of the piece1829-3relative to the piece1829-2is in an expanded position, as shown inFIGS.18A and18B. In this state, the cavity1845-1has a width1819-1, and the gap1839-1between the inner surface1851-2C of the body1821-2of the piece1829-2and the outer surface1852-3B of the body1821-3of the piece1829-3has a width1869-1. The width1819-1of the cavity1845-1can be the same as, or different than, the width1869-1of the gap1839-1. Also, the inner surface1851-3A of the piece1829-3extends inward by a distance1859-1relative to the inner surface1851-2A of the piece1829-2when the seat1820is in the default (expanded) position.

The seat1820has a height1867and a width (thickness)1868, where the width1868can change as the piece1829-2and/or the piece1829-3move between an expanded (default) position and a consolidated position relative to each other and/or relative to the piece1829-1. In this example, none of the pieces1829of the seat1820include any coupling features (such as the coupling features1792discussed above) that allow one piece1829(e.g., piece1829-2) to be movably coupled, directly or indirectly, to another piece (e.g., piece1829-3). The inner perimeter1857-3of the piece1829-3, the inner perimeter1857-2C of the piece1829-2, and the inner perimeter1857-1C of the piece1829-1can be substantially planar with respect to each other, regardless of the position (e.g., fully consolidated, partially consolidated, expanded) of the seat1820.

In this example, the size of the piece1829-2, the size of the cavity1845-2, and the size of the resilient device1838-2are larger than the size of the piece1829-1, the size of the cavity1845-1, and the size of the resilient device1838-1. Further, the properties (e.g., resistance, resiliency, material) of the resilient device1838-1can be the same as, or different than, the corresponding properties of the resilient device1838-2. Alterations to one or more of the characteristics of one or more of the pieces1829, the cavities1845, and/or the resilient devices1838can change the contact pressure of the seat1820against the wall of the gate valve at relatively low core pressures (e.g., less than 10% of RWP of the gate valve, less than 25% of RWP of the gate valve).

FIGS.19A and19Bshow a subsystem1999that includes the seat1820ofFIGS.18A and18Binteracting with a gate1915for a gate valve according to certain example embodiments. Specifically,FIG.19Ashows the subsystem1999with the portion of the seat1820shown inFIG.18Bin a partially consolidated position, andFIG.19Bshows the subsystem1999with the portion of the seat1820shown inFIG.18Bin a fully consolidated position. Referring toFIGS.1through19B, the gate1915of the subsystem1999can be substantially the same as the gates (e.g., gate1415) discussed above.

When the seat1820is in a partially consolidated position, as inFIG.19A, the gate1915applies a relatively small force against the seat1820. As a result, the piece1829-3of the seat1820is pushed inward relative to the piece1829-2, causing the resilient device1838-1to compress as the width1919-1of the cavity1845-1is reduced from its original width1819-1. Similarly, the width of the gap1839-1is reduced relative to its width1869-1when the seat1820is in the expanded (default) position.

Since the amount of force that is applied by the gate1915against the seat1820is relatively small, the gate1915in this example only abuts against, without forcing any movement of, the inner surface1852-2A of the piece1829-2. As a result, when the seat1820is in the partially consolidated position ofFIG.19A, the distance between the inner surface1851-1A of the piece1829-1and the gate1915is substantially the same as the distance1859-2that the inner surface1851-2A of the piece1829-2extends relative to the inner surface1851-1A of the piece1829-1. Also, the size of the resilient device1838-2within the cavity1845-2, the width1819-2of the cavity1845-2, and the width1869-2of the gap1839-2remain unchanged relative to when the seat1820is in the expanded position.

When the seat1820is in a fully consolidated position, as inFIG.19B, the gate1915applies a relatively large force against the seat1820. As a result, the piece1829-3of the seat1820is pushed inward relative to the piece1829-2, causing the resilient device1838-1to fully compress as the width2019-1is reduced from its original width1819-1and from its width1919-1when the seat is in the partially consolidated position. Similarly, the gap1839-1is eliminated so that the outer surface1852-3B of the piece1829-3abuts against the inner surface1851-2C of the piece1829-2.

In addition, the gate1915pushes the piece1829-2of the seat1820inward relative to the piece1829-1, causing the resilient device1838-2to compress as the width1919-2of the cavity1845-2is reduced from its original width1819-2. Similarly, the width of the gap1839-2is reduced relative to its width1869-2when the seat1820is in the expanded (default) position or the partially consolidated position. Further, the gate1915in this example only abuts against, without forcing any movement of, the inner surface1852-1A of the piece1829-1. Also, the size of the resilient device1838-2within the cavity1845-2, the width1919-2of the cavity1845-2, and the width1869-2of the gap1839-2are reduced relative to when the seat1820is in the expanded position or in the partially consolidated position.

The force that the gate1915applies against the seat1820to put the seat in the partially consolidated position, as inFIG.19A, causes the contact pressure to be elevated and substantially constant for low (e.g., less than 10% of RWP of the gate valve) bore pressures relative to what gate valves and associated seats in the current art can provide (as discussed above with respect toFIGS.4A,4B, and16). As the bore pressure increases (e.g., between 10% and 20% of RWP of the gate valve), the force that the gate1915applies to the seat1820increases, causing the seat to be in the fully consolidated position, as inFIG.19B. When this occurs, the contact pressure can have a step increase (e.g., from 6.5 kpsia to 10 kpsia, from 3 kpsia to 7 kpsia) relative to the contact pressure when the seat1820is in the partially consolidated position. Eventually, similar to what is shown inFIG.16with respect to the gate valve1400, when the bore pressure reaches a minimum amount (e.g., more than 20% of RWP of the gate valve), the contact pressure increases in a substantially linear manner.

Example embodiments may be used to provide systems and methods for seats for gate valves. Example embodiments result in a relatively high and substantially constant contact pressure within a gate valve at core pressures that are experienced by the gate valve most of the time during operations. As a result, example embodiments greatly reduce or eliminate failures of gate valves in the current art. Example embodiments can be used with new gate valves or retrofit into existing gate valves. Example embodiments may provide a number of benefits. Such benefits may include, but are not limited to, more reliable operation of gate valves, ease of installation and use, reducing downtime, flexibility, configurability, and compliance with applicable industry standards and regulations.