Patent ID: 12203559

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are used herein to designate like elements throughout, the various views and embodiments of gate valves and seats for a gate valve are illustrated and described, and other possible embodiments are described. The figures are not necessarily drawn to scale, and in some instances the drawings have been exaggerated and/or simplified in places for illustrative purposes only. One of ordinary skill in the art will appreciate the many possible applications and variations based on the following examples of possible embodiments.

FIGS.1-5illustrate a gate valve in accordance with one aspect. The gate valve100includes a valve body102defining a flow bore104formed through the valve body for fluid flow along a bore axis106. Unless otherwise specified, the terms “axial” and “axially” as used herein describe directions parallel to the bore axis106, and the terms “radial” and “radially” as used herein describe directions towards (i.e., “inwardly radial”) and away from (i.e., “outwardly radial”) the bore axis and distances measured with respect to the bore axis. The valve body102further defines an internal cavity108extending along a stem axis110perpendicular to the bore axis106. A gate112having a gate bore114is mounted in the cavity108and is movable along the stem axis110to selectively enable or block fluid flow through the flow bore104. The valve body102may further define flanges116each end of the flow bore104to facilitate connection to other components of the piping system. The first shoulder of the seat154is defined by the outwardly radial face178and an axial face179extending radially outward therefrom at a first corner184.

As best seen inFIG.2, fluid flow through the gate valve100is enabled when the gate112is positioned along the stem axis110such that at least a portion of the gate bore114is aligned with at least a portion of the flow bore104(i.e., valve in the “open” position). Referring still toFIG.2, the gate valve100in the open position allows a fluid118to enter the flow bore104from an upstream side120, pass thorough the aligned gate bore114, and then exit the gate valve from a downstream side122. As best seen inFIG.4, fluid flow through the gate valve100is blocked when the gate112is positioned such that none of the gate bore114is aligned with the flow bore104(i.e., valve in the “closed” position). Referring still toFIG.4, the gate valve100in the closed position allows the fluid118to enter the fluid bore104from the upstream side120, but further flow past the gate112is blocked.

The gate valve100further includes a bonnet assembly124coupled to the valve body102. The bonnet assembly124includes a bonnet housing126, an operating stem128and a bonnet packing assembly130. The bonnet housing126may serve as a cover to the valve body102, with the bonnet housing coupled to the valve body using removable fasteners, e.g., threaded studs132and threaded nuts126. A bonnet gasket136can be used between to provide a pressure seal between the valve body102and the bonnet housing126. The operating stem128extends within the bonnet housing126along the stem axis110and is operably attached to the gate112for selectively moving the gate within the valve body102. In the illustrated embodiment, the operating stem128is operably connected to an external handwheel138on an upper end and threadingly engaged to a T-nut140on a lower end, the T-nut, in turn, being attached to the gate112. Selectively rotating the handwheel138rotates the connected operating stem128, and rotation of the operating stem causes the threadingly engaged T-nut140to move up and down along the stem axis110to move the gate112between the open position and the closed position. In alternative embodiments, a powered actuator can be used to move the gate112.

The bonnet packing assembly130can include a packing housing142, a stem adapter144interfacing between the handwheel138and the operating stem128, support bearings146, a stem packing gland148and stem packing and/or stem seal150for sealing between the bonnet housing126. As previously described, the gate valve100is configured so as the handwheel138is actuated (or some similar operator is actuated), the operating stem128is moved so the gate112can either close or open the flow bore104in the valve body102. When the gate112is in an open position, fluid118is allowed to flow through the flow bore104(seeFIG.2) in the valve body102. When the gate112is in a closed position, the flow of fluid118is blocked within the flow bore104.

Referring still toFIGS.1-5, and especially toFIGS.3and5, a seat assembly152is provided on each side of the gate112between the valve body102and the gate to prevent or lessen leakage of high pressure fluid118from the upstream portion of the flow bore104into the cavity108when the gate is closed. The seat assemblies152further prevent or lessen leakage of high pressure fluid118from the cavity108into the downstream portion of the flow bore104when the gate112is closed. The gate valve100and the seat assembly152are configured to be equally resistant to the leakage of pressurized fluid regardless of which flange is on the upstream (i.e., higher pressure) side of the gate112. In other words, the gate valve100is a bidirectional valve such that either the upstream line or the downstream line can be attached to either side120,122of the valve body102.

FIGS.3and5provide enlarged illustrations of the seat assemblies152with the gate112in the open position and the closed position, respectively. For purposes of description, the upstream side of the valve is denoted120and the downstream side is denoted122, thus the seat assembly denoted152′ is the upstream assembly and the seat assembly denoted152″ is the downstream assembly in this example. However, since the gate valve100of the illustrated embodiment is bi-directional, the valve would function identically if the pressure and flow direction was reversed.

Each seat assembly152includes a seat154, seat spring156, an upstream seal158and a downstream seal160. Each seat154has an annular shape configured fit within a respective pocket155(FIG.7) formed in the valve body102on either side of the cavity108along the bore axis106. Each seat154further defines a seat bore161running therethrough that can be aligned with the flow bore104. A retainer plate162can be provided in the cavity108to hold the seats154within their respective seat pockets155.FIG.3shows the gate valve100in the open position with the gate bore114aligned along the bore axis106with the seat bores161and the flow bore104such that pressurized fluid118can flow through the gate valve along the bore axis from the upstream side120having a higher pressure to the downstream side122having a lower pressure.FIG.5shows the gate valve100in the closed position with the gate bore114offset from the bore axis106of the flow bore104and seat bores161such that pressurized fluid118from the upstream side120cannot flow past the gate112along the bore axis.

Referring now also toFIG.6, a portion of the downstream seat assembly152″ is further enlarged to better illustrate the configuration of the upstream seal158, downstream seal160and seal spring156. AlthoughFIG.6illustrates the downstream seat assembly152″, the upstream seat assembly152′ can be substantially identical in construction (though reversed in orientation). Also note that the each of the upstream and downstream seat assemblies152′ and152″ includes both the upstream seal158and downstream seal160for reasons described herein.

The seat springs156are annular disk springs disposed in seat spring pockets163formed on the outward facing ends of the seats154(i.e., the ends facing away from the gate112). When the seat154is pushed into the seat pocket155, the seat spring156is compressed between the inward facing end of the seat pocket and the outward facing end of the seat spring pocket163, thus biasing the seat inward against the gate112. This inward biasing of the seat154allows the inward facing ends of the seats112to maintain contact with the surface of the gate112as it moves between the open and closed position.

In preferred embodiments, the upstream seal158and the downstream seal160are annular seals of the spring energized type. Each seal158,160includes an annular body164having a V-shaped or U-shaped concave surface166forming a pair of seal lips168extending from the body. The seals158,160may be composed of polymer, elastomeric, non-elastomeric, and/or metallic material or some combination thereof and are configured to be suitable to any application depending on the variability of environmental factors such as flow pressure (low/high) and temperature. A V-shaped seal spring170is disposed between the seal lips168and stabilized by a hat ring172. A reinforcing ring174can be provided in the body164of the seal to prevent extrusion of the material due to high pressures or temperatures.

When the seats154carrying the seals158,160are installed in the respective seat pockets155(FIG.7) of the valve body102, the seal springs170of the seals are compressed between the respective faces of the seat and the seat pocket. In other words, when installed, each seal spring170is pushing outward against the compression, creating an initial upstream seal using spring force to push the seal lips168of the upstream seal158against an upstream pocket face176and an upstream seat face178, and creating an initial downstream seal using spring force to push the seal lips of the downstream seal160outward against a downstream pocket face180and a downstream seat face182. When pressure from pressurized fluid in the gate valve is applied to the concave surface166of either seal158or160, the force from the pressure is added to the spring force from the seal spring170to increasingly press the seal lips168of that respective seal against the respective faces of the seat and seat pocket, thereby preventing leakage of pressure or fluid. These spring energized seals, however, work only when the pressure is applied to the concave surface side of the seal158,160; otherwise the pressure and fluid can leak by the seal relatively easily. Thus, to provide a bi-directional seal from pressure coming from either direction of the valve body, the leak-resistant orientation of the seal in the downstream seal160is reversed from the leak-resistant orientation of the upstream seal158.

In the illustrated example, pressure from the upstream side120will activate the upstream seal158′ of the upstream seat assembly152′ and stop any leakage if the seal and seat are in good condition. However, if the upstream seal158′ or seat are worn or damaged, pressurized fluid leaking past the upstream seal will be able to pass the downstream seal160′ of that seat assembly and flow into the cavity108, because the concave surface166of the downstream seal is oriented in the wrong direction. Pressurized fluid in the cavity108would then enter the downstream seat assembly152″ and activate the downstream seal160″ of the downstream seat assembly. This downstream seal160″ will stop any leakage from the cavity108if the seal and seat are in good condition. However, if the downstream seal160″ or seat are worn or damaged, pressurized fluid leaking past the downstream seal will also pass the upstream seal158″ of that seat assembly and flow into the flow bore104downstream of the gate112. In this case, the seats and/or seals will have to be replaced.

Referring still toFIGS.1-8, more features of the gate valve100are described. As previously discussed, the gate valve100comprises a valve body102including a cavity108in fluid communication with a flow bore104. As best seen inFIG.8, the flow bore104defines a bore axis106passing through the valve body and having a first outer bore portion defined by a first body portion (e.g., left flange116) on a first side of the cavity and a second outer bore portion defined by a second body portion (e.g., right flange116) on a second side of the cavity. An annular first seat154(e.g., the left seat inFIG.3) is disposed in a first pocket155(best seen inFIG.8) formed on an inner surface of the first body portion adjacent the cavity108. The first seat154has a seat bore161therethrough forming a first inner bore portion of the flow bore104. The pocket155illustrated inFIG.8has a cylindrical configuration. An annular second seat154(e.g., the right seat inFIG.3) is disposed in a second pocket155formed on an inner surface of the second body portion adjacent the cavity108. The second seat154has a seat bore161therethrough forming a second inner bore portion of the flow bore104. It is preferred, but not required, that the first and second seats154are identical in configuration, although reversed in axial orientation. It is similarly preferred, but not required, that the first and second pockets155are identical in configuration, although reversed in axial orientation. It is further preferred, but not required, that the seat pockets155are cylindrical pockets. A gate112is disposed in the cavity108between the first seat154and the second seat154and is movable along a stem axis110perpendicular to the bore axis106between an open gate position (e.g.,FIGS.2and3) and a closed gate position (e.g.,FIGS.4and5). When the gate112is in the open gate position, a gate bore114formed therethrough is aligned with the first inner bore portion and the second inner bore portion respectively, of the first and second seats154to allow flow through the valve body102, and when the gate is in the closed gate position, the gate bore is not aligned with the first inner bore portion and the second inner bore portion to block flow through the valve body. A first upstream seal158(e.g., part of the left seat assembly152′) is disposed between a first upstream pair of opposing faces of the first seat154and the first pocket155. The first upstream pair of opposing faces are oriented parallel to the bore axis106and the first upstream seal158is configured to prevent fluid from moving in a direction from the flow bore104into the cavity108. A first downstream seal160is disposed between a first downstream pair of opposing faces of the first seat154and the first pocket155. The first downstream pair of opposing faces are oriented perpendicular to the bore axis106and the first downstream seal160is configured to prevent fluid from moving in a direction from the cavity108into the flow bore104.

Referring now especially toFIG.6, in some embodiments, the upstream pair of opposing faces includes an outwardly radial face178of a first shoulder of the seat154and an inwardly radial face176of the pocket155. Unless otherwise specified, the terms “inwardly radial” and “outwardly radial” as used herein describe directions with respect to the bore axis106. The first shoulder of the seat154is defined by the outwardly radial face178and an axial face179extending radially outward therefrom at a first corner184. In the illustrated embodiment, the first shoulder is formed at an axial end of the seat154adjacent the body portion102.

Referring now still toFIG.6, in some embodiments, the upstream seal158is a spring energized seal including a flexible polymeric jacket having a pair of sealing lips168extending from a jacket base164to form, when viewed in cross section, a V-shaped or a U-shaped cup166. A metallic energizing spring170is disposed in the cup166of the jacket between the sealing lips168to bias the sealing lips outwards relative to one another against the upstream pair of opposing faces176,178. The sealing lips168(i.e., the exterior surfaces of the lips) of the upstream seal158extend parallel to the bore axis106and an opening of the cup between the sealing lips (i.e., on the opposite side from the jacket base164) faces axially away from the108toward the pocket. The upstream seal158can include a hat ring172extending into the cup166to stabilize the spring170. The upstream seal158can include a reinforcing ring174around the jacket base164to reduce material flow (i.e., “creep”) when the seal is pressurized. In the illustrated embodiment, the base of the upstream seal158is supported on the axial surface179of the first shoulder.

Referring still toFIG.6, in some embodiments, the downstream pair of opposing faces includes an axial face182of a second shoulder formed on the seat154and an axial face180of the pocket155. The second shoulder of the seat154is defined by an outwardly radial surface183of the seat and the axial face182extending radially outward therefrom at a second corner186. In the illustrated embodiment, the outwardly radial surface178of the first shoulder and an outwardly radial surface183of the second shoulder are disposed at different radial distances from the bore axis106. In the illustrated embodiment the axial face182of the second shoulder faces toward the body portion102(i.e., away from the gate112).

In some embodiments, the downstream seal160is a spring energized seal including a flexible polymer jacket having a pair of sealing lips168extending from a jacket base164to form, when viewed in cross section, a V-shaped or a U-shaped cup166. A metallic energizing spring170is disposed in the cup of the jacket between the sealing lips168to bias the sealing lips outwards relative to one another against the downstream pair of opposing faces180,182. The sealing lips168of the downstream seal160are oriented perpendicular to the bore axis106and an opening of the cup166between the sealing lips faces radially away from the bore axis. In the illustrated embodiment, the base of the downstream seal160is supported on the outwardly radial surface183of the second shoulder.

As shown inFIG.6, when the seat154carrying the upstream seal158and the downstream seal160is installed in the pocket155, i.e., by sliding the seat axially into the pocket, it can be seen that the seat and the pocket are configured to axially compress the sealing lips168of the downstream seal between the downstream opposing faces180,182without experiencing sliding contact of either sealing lip across a stationary surface. Eliminating the sliding contact between the sealing lips168of the downstream seal160and the pocket surfaces during installation greatly reduces the chance for damaging the sealing lips, which can result in leakage and/or failure of the seal.

Referring still toFIG.6, in some embodiment, the first shoulder and the second shoulder of the seat154are separated from one another by at least one axially-oriented intervening surface of the first seat and one radially-oriented intervening surface of the first seat. In the illustrated embodiment, the first shoulder includes radial surface178and axial surface179joined at a first corner184, the second shoulder includes radial surface183and axial surface182joined at a second corner186, and these two shoulders are separated by an intervening third shoulder including an axially-oriented intervening surface188and a radially-oriented intervening surface190joined at a third corner192. Unless otherwise specified, the term “intervening surface” as used herein describes a surface that is disposed between two surfaces of the same element, but is not a linear extension of either of the other surfaces. Thus, the axially oriented surface188of the third shoulder of the seat154is an intervening surface with respect to the radial surface183of the second shoulder and the axial surface179of the first shoulder because it is not a linear extension of either of these seat surfaces (i.e., the three surfaces are separated by corners). Similarly, the radially oriented surface190of the third shoulder of the seat154is an intervening surface with respect to the radial surface183of the second shoulder and the axial surface179of the first shoulder because it is not a linear extension of either of these seat surfaces.

The configuration of gate valve100described herein having the seat154with the upstream seat seal surface178being parallel to the bore axis106and the downstream seat seal surface182being perpendicular to the bore axis, and having the corresponding pocket155with the upstream pocket seal surface176being parallel to the bore axis and the downstream pocket seal surface180being perpendicular to the bore axis, addresses a problem commonly encountered in conventional gate valves. Namely, when the upstream and downstream seal surfaces of the seats and/or pockets are aligned in conventional gate valves, a single scratch or gouge on the seat or pocket can damage both the upstream and downstream seal surfaces, thus causing leakage of both the upstream and downstream seals. In contrast, since the gate valve100has seats154and pockets155configured with upstream and downstream respective seal surfaces that are perpendicular to one another, a single scratch or gouge is unlikely to damage both the upstream and downstream seal surfaces, thereby leaving at least one of the two seals undamaged and able to resist leakage.

Further, the configuration of gate valve100having the seat154with the seat upstream seal surface178disposed on a first shoulder and the downstream seal surface182disposed on a second shoulder, wherein the two shoulders are separated by an intervening third shoulder, addresses the same previously-described problem commonly encountered in conventional gate valves. Since the upstream and downstream seat seal surfaces178,182are isolated from one another by an intervening shoulder188,190of the seat154, a single scratch or gouge on the seat is unlikely to damage both the upstream and downstream seat seal surfaces.

Referring still toFIG.6, in some embodiment, the inwardly radial face176of the pocket155(i.e., that opposes the outwardly radial surface178of the seat's first shoulder) and the axial face180of the pocket (i.e., that opposes the axial surface182of the seat's second shoulder) are separated from one another by at least one intervening surface of the pocket that is not perpendicular to the bore axis106and is not parallel to the bore axis. In the illustrated embodiment, the inwardly radial face176and the axial face180are separated by an intervening angled surface194that is neither perpendicular nor parallel to the bore axis106. The configuration of the pocket155having the pocket upstream seal surface176and the pocket downstream seal surface180isolated by an intervening angled surface protects against damage to the upstream and downstream pocket seal surfaces.

Referring now back toFIGS.3and5, in another embodiment, the gate valve100further comprises a second upstream seal158(e.g., part of the right seat assembly152″) disposed between a second upstream pair of opposing faces of the second seat154(i.e., the right seat) and the second pocket155(i.e., the right pocket). The second upstream pair of opposing faces are oriented parallel to the bore axis106. The second upstream seal158is configured to prevent fluid from moving in a direction from the flow bore104into the cavity108. A second downstream seal160is disposed between a second downstream pair of opposing faces of the second seat154and the second pocket155. The second downstream pair of opposing faces are oriented perpendicular to the bore axis106, wherein the second downstream seal is configured to prevent fluid from moving in a direction from the cavity108into the flow bore104.

Referring still toFIGS.3and5, in another embodiment, the second upstream pair of opposing faces includes a outwardly radial face of a first shoulder formed at an axial end of the second seat154adjacent the second body portion102and an inwardly radial face of the second pocket155. The second downstream pair of opposing faces can include an axial face of a second shoulder formed on the second seat154facing toward the second body portion102. Outward radial surfaces of the first shoulder and the second shoulder of the second seat154can be disposed at different radial distances from the bore axis106, and axial surfaces of the first shoulder and the second shoulder of the second seat can be disposed at different axial distances from the axial end of the second seat adjacent to the first body portion. The second downstream pair of opposing faces can also include an axial face of the second cylindrical pocket155facing toward the cavity108(i.e., towards the gate112).

Referring once again toFIG.6, in one embodiment, a first seat face178that is one of the first upstream pair of opposing faces176,178and a second seat face182that is one of the first downstream pair of opposing faces180,182are disposed on different faces of the seat154. A first pocket face176that is one of the first upstream pair of opposing faces176,178and a second pocket face180that is one of the first downstream pair of opposing faces180,182are disposed on different faces of the first pocket155.

Referring now toFIGS.3and5-8, in another aspect, a seat assembly152for a gate valve100is configured for mounting in a pocket155formed on an inner surface of a gate valve body102. The seat assembly152comprises a seat154, an upstream seal158and a downstream seal160. The seat154has a seat bore161formed therethrough from a pocket side to a gate side defining a bore axis106, a first shoulder178,179for mounting an upstream seal158and a second shoulder182,183for mounting a downstream seal160. The first shoulder includes a first outwardly radial face178disposed at a first radius from the bore axis106and extending axially from a first position at a first distance relative to the pocket side122of the seat154to a first corner184disposed at a second distance relative to the pocket side, the second distance being greater than the first distance. The first shoulder further includes a first axial face179extending radially outward from the first corner184to a second radius from the bore axis106, the second radius being greater than the first radius. The second shoulder includes a second outwardly radial face183disposed at a third radius from the bore axis and extending axially from a second position at a third distance relative to the pocket side122of the seat154to a second corner186disposed at a fourth distance relative to the pocket side, the fourth distance being greater than the third distance. The second shoulder further includes a second axial face182extending radially outward from the second corner186to a fourth radius from the bore axis, the fourth radius being greater than the third radius. The upstream seal158is adapted for mounting on the first shoulder to prevent fluid flow in an axial direction from the pocket side122toward the gate side. The downstream seal160is adapted for mounting on the second shoulder to prevent fluid flow in a radial direction toward the bore axis106.

The annular seat154of the seat assembly152can further comprises a third shoulder188,190disposed axially between the first shoulder178,179and the second shoulder182,183. In some embodiments, the third shoulder188,190includes a third outwardly radial face190disposed at the second radius from the bore axis106and extending axially to a third corner192, the third corner disposed axially between the first corner and the second corner, and a third axial face188extending radially outward from the third corner. In some embodiments, the third corner188,190is disposed at the third distance from the pocket side122and the third axial face188extends radially outward from the third corner192to the third radius from the bore axis106.

As best seen inFIG.6, in some embodiments of the seal assembly152, the upstream seal158is a spring energized seal including a flexible polymeric jacket having a pair of sealing lips168extending from a jacket base164to form, when viewed in cross section, a V-shaped or a U-shaped cup166. A metallic energizing spring170is disposed in the cup166of the jacket between the sealing lips168to bias the sealing lips outwards relative to one another. The jacket base164of the upstream seal158is configured to mount against the first axial face179of the first shoulder and one of the pair of sealing lips168of the upstream seal is configured to mount against the first outwardly radial face178of the first shoulder.

In some embodiments, the downstream seal160is a spring energized seal including a flexible polymeric jacket having a pair of sealing lips168extending from a jacket base164to form, when viewed in cross section, a V-shaped or a U-shaped cup166. A metallic energizing spring170is disposed in the cup166of the jacket between the sealing lips168to bias the sealing lips outwards relative to one another. The jacket base164of the downstream seal160is configured to mount against the second outwardly radial face183of the second shoulder and one of the pair of sealing lips168of the downstream seal is configured to mount against the second axial face182of the second shoulder.

Referring now again toFIGS.3and5-8, in yet another aspect, a seat154for a gate valve is configured for mounting in a pocket155formed on an inner surface of a gate valve body102. The seat154comprises an annular body having a seat bore161formed therethrough from a pocket side to a gate side defining a bore axis106, a first shoulder178,179configured for mounting an upstream seal158and a second shoulder182,183configured for mounting a downstream seal160. The first shoulder includes a first outwardly radial face178disposed at a first radius from the bore axis106and extending axially from a first position at a first distance relative to the pocket side122of the seat154to a first corner184disposed at a second distance relative to the pocket side, the second distance being greater than the first distance. The first shoulder also includes a first axial face179extending radially outward from the first corner184to a second radius from the bore axis106, the second radius being greater than the first radius. The second shoulder includes a second outwardly radial face183disposed at a third radius from the bore axis106and extending axially from a second position at a third distance relative to the pocket side122of the seat154to a second corner186disposed at a fourth distance relative to the pocket side, the fourth distance being greater than the third distance. The second shoulder also includes a second axial face182extending radially outward from the second corner to a fourth radius from the bore axis106, the fourth radius being greater than the third radius.

In some embodiments, the annular seat154further comprises a third shoulder188,190disposed axially between the first shoulder178,179and the second shoulder182,183. The third shoulder includes a third outwardly radial face190disposed at the second radius from the bore axis106and extending axially to a third corner192, the third corner disposed axially between the first corner184and the second corner186. The third shoulder also includes a third axial face188extending radially outward from the third corner192. In some embodiments, the third corner192is disposed at the third distance from the pocket side122and the third axial188face extends radially outward from the third corner to the third radius from the bore axis.

FIGS.9-15illustrate a gate valve having a dual seat arrangement in accordance with another aspect. The gate valve900includes a valve body902defining a flow bore904formed through the valve body for fluid flow along a bore axis106. The terms “axial” and “axially” as used herein describe directions parallel to the bore axis106, and the terms “radial” and “radially” as used herein describe directions towards (i.e., “inwardly radial”) and away from (i.e., “outwardly radial”) the bore axis and distances measured with respect to the bore axis. The valve body902further defines an internal cavity908extending along a stem axis110perpendicular to the bore axis106. A gate912having a gate bore914is mounted in the cavity908and is movable along the stem axis110to selectively enable or block fluid flow through the flow bore904. The valve body902may further define flanges916at each end of the flow bore904to facilitate connection to other components of the piping system. A dual seat assembly952comprising a seat retainer953, a seat954and associated seals and springs (as further described), is disposed on each respective side of the gate912along the flow bore904between the gate and a respective inner surface of the valve body902. In typical embodiments, the seats954and seat retainers953are formed of metallic materials or metallic alloy materials including, but not limited to carbon steel, steel alloys, corrosion resistant alloy (CRA) and other high strength, wear-resistant materials. In typical embodiments, the associated seals have sealing surfaces formed of non-metallic materials including, but not limited to polymers, natural and synthetic elastomers, non-elastomeric plastics and other flexible non-metallic materials. In some embodiments, the associated seals can have internal metallic components that serve to energize or reinforce the external non-metallic sealing surfaces.

As best seen inFIG.10, fluid flow through the gate valve900is enabled when the gate912is positioned along the stem axis110such that at least a portion of the gate bore914is aligned with at least a portion of the flow bore904(i.e., valve in the “open” position). Referring still toFIG.10, the gate valve900in the open position allows a fluid118to enter the flow bore904from an upstream side120, pass thorough the aligned gate bore914, and then exit the gate valve from a downstream side122. As best seen inFIG.12, fluid flow through the gate valve900is blocked when the gate912is positioned such that none of the gate bore914is aligned with the flow bore904(i.e., valve in the “closed” position). Referring still toFIG.12, the gate valve900in the closed position allows the fluid118to enter the fluid bore904from the upstream side120, but flow past the gate112is blocked.

The gate valve900further includes a bonnet assembly924coupled to the valve body902. The bonnet assembly924includes a bonnet housing926, an operating stem928and a bonnet packing assembly930. The bonnet housing926may serve as a cover to the valve body902, with the bonnet housing coupled to the valve body using removable fasteners, e.g., threaded studs932and threaded nuts934. A bonnet gasket936can be used between to provide a pressure seal between the valve body902and the bonnet housing934. The operating stem928extends within the bonnet housing926along the stem axis110and is operably attached to the gate912for selectively moving the gate within the valve body902. In the illustrated embodiment, the operating stem928is operably connected to an external handwheel938on an upper end and threadingly engaged to a T-nut940on a lower end, the T-nut, in turn, being attached to the gate912. Selectively rotating the handwheel938rotates the connected operating stem928, and rotation of the operating stem causes the threadingly engaged T-nut940to move up and down along the stem axis110to move the gate912between the open position and the closed position. In alternative embodiments, a powered actuator can be used to move the gate912.

The bonnet packing assembly930can include a packing housing942, a stem adapter944interfacing between the handwheel938and the operating stem928, support bearings946, a stem packing gland948and stem packing and/or stem seal950for sealing between the stem and the bonnet housing926. As previously described, the gate valve900is configured so as the handwheel938is actuated (or some similar operator is actuated), the operating stem928is moved so the gate912can either close or open the flow bore904in the valve body902. When the gate912is in an open position, fluid118is allowed to flow through the flow bore904(seeFIG.10) in the valve body902. When the gate912is in a closed position, the flow of fluid118is blocked within the flow bore904.

Referring now in particular toFIG.10, a dual seat assembly952is provided on each side of the gate912between the valve body902and the gate. The dual seat assemblies952constitute removable wear elements that can be replaced when they become eroded, worn or damaged without replacing the entire valve body902. For example,FIG.10shows a first dual seat assembly952′ disposed on the first side of the gate912and a second dual seat assembly952″ disposed on the second side of the gate. The dual seat assemblies952include fluid seals to prevent or lessen so-called “upstream leakage”, i.e., leakage of high-pressure fluid118from the upstream portion of the flow bore904into the cavity908when the gate is closed. The dual seat assemblies952further include separate fluid seals to prevent or lessen so-called “downstream leakage”, i.e., leakage of high-pressure fluid118from the cavity908into the downstream portion of the flow bore904when the gate912is closed. The gate valve900and the seat assemblies952may be configured to be equally resistant to the leakage of pressurized fluid regardless of which flange is on the upstream (i.e., higher pressure) side of the gate912. In other words, the gate valve900can be a bidirectional valve such that either the upstream line or the downstream line can be attached to either side120,122of the valve body902.

Referring again toFIGS.9-15, further details of the dual seat assemblies952are disclosed. As previously discussed, the gate valve900includes a valve body902having the cavity908in fluid communication with a flow bore904. The flow bore904defines a bore axis106through the valve body902having a first outer bore portion, denoted904a′ (FIG.10), defined by a first body portion on a first side of the cavity908, and a second outer bore portion, denoted904a″ (FIG.10), defined by a second body portion on a second side of the cavity. Each respective dual seat assembly152comprises a respective annular seat retainer953and a respective annular seat954disposed on a respective side of the gate912. Thus, as shown inFIG.11, a first dual seat assembly952′ comprises a first seat retainer953′ and a first seat954′ disposed on the first side of the gate912, and a second dual seat assembly952″ comprises a second seat retainer953″ and a second seat954″ disposed on the second side of the gate.

Referring, e.g., toFIG.11, each respective seat retainer953has an annular configuration defining a retainer wall portion974having a relatively-smaller outer radius extending from a retainer rim portion976having a relatively-larger outer radius, with a retainer bore extending through both portions forming a respective intermediate bore portion904bof the flow bore904. Thus, the retainer bore of first seat retainer953′ forms the first intermediate bore portion904b′, and the retainer bore of second seat retainer953″ forms the second intermediate bore portion904b″. Each respective seat954has an annular configuration defining a seat wall portion978having a relatively-smaller outer radius extending from a seat rim portion980having a relatively-larger outer radius, with a seat bore of constant inner radius extending through both portions forming a respective inner bore portion904cof the flow bore904. Thus, the seat bore of first seat954′ forms the first inner bore portion904c′, and the seat bore of second seat954″ forms the second inner bore portion904c″.

The gate912is disposed in the cavity908between the first seat954′ and the second seat954″ and is movable along the stem axis110(which is perpendicular to the bore axis106) between an open gate position and a closed gate position. For example, when the gate912is in the open gate position (e.g.,FIGS.10,11), the gate bore914formed therethrough is aligned with the first portion of the bore904including the first outer bore portion904a′, first intermediate bore portion904b′ and first inner bore portion904c′ and with the second portion of the bore including the second inner bore portion904c″, second intermediate bore portion904b″ and second outer bore portion904a″, to allow flow118through the valve body902. When the gate912is in the closed gate position (e.g.,FIGS.12,13), the gate bore914is not aligned with first and second portions of the flow bore904, thus blocking fluid flow through the valve body902.

An axially outward facing end (i.e., facing away from the gate912) of the wall portion974of each respective seat retainer953is received in a respective retainer pocket955(see, e.g.,FIG.15) formed in the axially inward facing side (i.e., facing toward the gate) of the gate valve body portion902along the bore axis106, with the axially outward facing surface of the rim portion976of the seat retainer abutting the body portion surrounding to the retainer pocket. Thus, as shown inFIG.11, a first seat retainer953′ is received in a first retainer pocket955′ formed on an inward facing surface of the first body portion, and a second seat retainer953″ is received in a second retainer pocket955″ formed on an inward facing surface of the second body portion. An axially outward end of the wall portion978of each respective seat954is received in a seat pocket957formed in the axially inward facing side of the respective seat retainer953along the bore axis106, with the axially outward facing surface of the rim portion980of the seat abutting the axially inward facing surface of the rim portion976of the seat retainer. Thus, the outward facing wall portion978′ of the first seat954′ is received in a first seat pocket957′ formed on an inward facing surface of the first seat retainer953′, with the outward facing wall portion974′ of the first seat retainer received in the first retainer pocket955′ formed on an inward facing surface of the valve body902. Similarly, the outward facing wall portion978″ of the second seat954″ is received in a second seat pocket957″ formed on an inward facing surface of the second seat retainer953″, with the outward facing wall portion974″ of the second seat retainer received in the second retainer pocket955″ formed on a second inward facing surface of the valve body902.

As best seen inFIGS.11and13, each respective dual seat assembly952further comprises a respective first pair of fluid seals disposed along an outer interface between the seat retainer953and the valve body902to block fluid leakage along the outer interface, and a respective second pair of fluid seals disposed along an inner interface between the seat retainer953and the seat954to block fluid leakage along the inner interface. In the context of this disclosure, the term “interface” refers to the boundary between respective discrete elements, e.g., between a seat and a seat pocket, where opposing surfaces come into contact with, or close proximity to, one another, but where the opposing surfaces are not permanently attached to one another. In the absence of seals, fluids can leak along interfaces when a pressure differential is present between opposite ends of the interface. In particular, the first pair of fluid seals includes a retainer upstream seal958and a retainer downstream seal966disposed along the outer interface between the seat retainer953and the valve body902, and the second pair of fluid seals includes a seat upstream seal962and a seat downstream seal970disposed along the inner interface between the seat retainer953and the seat954. In the context of the upstream seals958and962and the downstream seals966and970, the terms “upstream” and “downstream” do not relate to the location of the seals relative to which end of the gate valve900is actually pressurized. Rather, the term “upstream seal” is used to denote seals configured to restrict the flow of pressurized fluid118moving in a direction from the flow bore904toward the cavity908, whereas the term “downstream seal” is used to denote seals configured to restrict the flow of pressurized fluid moving in a direction from the cavity towards the flow bore.

The respective orientations of the upstream and downstream seals958,960,962,966refers to the respective direction of fluid flow that each respective seal is configured to block. For example, in the illustrated embodiment ofFIGS.9-15, the retainer upstream seal958is configured to block fluid flow along an axial portion of the outer interface, and thus is considered to have an axial orientation. Similarly, the seat upstream seal962is configured to block fluid flow along an axial portion of the inner interface, and this is also considered to have an axial orientation. On the other hand, in the illustrated embodiment, the retainer downstream seal966is configured to block fluid flow along a radial portion of the outer interface, and thus is considered to have a radial orientation. Similarly, the seat downstream seal970is configured to block fluid flow along a radial portion of the inner interface, and this is also considered to have a radial orientation.

In some embodiments, the upstream seals of each dual seat assembly952are oriented perpendicular to the downstream seals in both pairs of the fluid seals. E.g., retainer upstream seal958is oriented perpendicular to retainer downstream seal966, and seat upstream seal962is oriented perpendicular to seat downstream seal970. In some embodiments, both upstream seals of each dual seat952assembly have the same orientation as one another, and both downstream seals have the same orientation as one another, but different from that of the upstream seals. E.g., retainer upstream seal958and seat upstream seal962have the same first orientation as each other, and retainer downstream seal966and seat downstream seal970have the same second orientation as each other, but different from the first orientation of the two upstream seals. In some embodiments, both upstream seals958,962of each dual seat assembly952are oriented axially (i.e., parallel to the bore axis106), and both downstream seals966,970are oriented radially (i.e., perpendicular to the bore axis).

As best seen inFIG.14, each respective dual seat assembly952further comprises a respective retainer upstream seal958disposed along the outer interface between the respective seat retainer953and valve body902. For purposes of simple illustration, the respective elements inFIG.14are not denoted first (′) or second (″). In the illustrated embodiment, the retainer upstream seal958is disposed between a retainer upstream pair of opposing faces960,961of the respective seat retainer953and retainer pocket955. Specifically, face960is a radially-inward facing surface of the retainer pocket955, and face961is a radially-outward facing shoulder formed on the wall portion974of the seat retainer953. In the illustrated embodiment, the retainer upstream pair of opposing faces960,961are oriented parallel to the bore axis106. The retainer upstream seal958is configured to prevent fluid118from moving in a direction from the flow bore904towards the cavity908.

Each respective dual seat assembly952further comprises a respective seat upstream seal962disposed along the inner interface between the respective seat retainer953and seat954. In the illustrated embodiment ofFIG.14, the seat upstream seal962is disposed between a seat upstream pair of opposing faces963,964of the respective seat954and seat pocket957. Specifically, face963is a radially-inward facing surface of the seat pocket957, and face964is a radially-outward facing shoulder formed on the wall portion978of the seat954. In the illustrated embodiment, the seat upstream pair of opposing faces963,964are oriented parallel to the bore axis106. The seat upstream seal962is configured to prevent fluid118from moving in a direction from the flow bore904toward the cavity908.

Each respective dual seat assembly952still further comprises a respective retainer downstream seal966disposed along the outer interface between the respective seat retainer953and valve body902. In the illustrated embodiment ofFIG.14, the retainer downstream seal966is disposed between a retainer downstream pair of opposing faces967,968of the respective seat retainer953and valve body902. Specifically, face967is an axially-inward facing (i.e., toward the gate912) shoulder on the valve body902surrounding the retainer pocket955, and face968is a axially-outward facing groove formed on the rim portion976of the seat retainer953. In the illustrated embodiment, the retainer downstream pair of opposing faces967,968are oriented perpendicular to the bore axis106. The retainer downstream seal966is configured to prevent fluid118from moving in a direction from the cavity908toward the flow bore904.

Each respective dual seat assembly952yet further comprises a respective seat downstream seal970disposed along the inner interface between the respective seat retainer953and seat954. In the illustrated embodiment ofFIG.14, the seat upstream seal962is disposed between a retainer downstream pair of opposing faces971,972of the respective seat retainer953and seat954. Specifically, face971is an axially-inward facing surface of the rim portion976of the seat retainer953, and face972is a axially-outward facing groove formed on the rim portion980of the seat954. In the illustrated embodiment, the seat downstream pair of opposing faces971,972are oriented perpendicular to the bore axis106. The seat downstream seal972is configured to prevent fluid118from moving in a direction from the cavity908toward the flow bore904.

In preferred embodiments, the seals958,962,966and970of the dual seat assemblies952are annular seals of the spring energized type substantially similar to seals158and160previously describe in connection with gate valve100. As best seen inFIG.14, such seals can include an annular body164having a V-shaped or U-shaped concave surface166forming a pair of seal lips168extending from the body. The seals958,962,966and970may be composed of polymer, elastomeric, non-elastomeric, and/or metallic material or some combination thereof and are configured to be suitable to any application depending on the variability of environmental factors such as flow pressure (low/high) and temperature. A V-shaped seal spring170can be disposed between the seal lips168and stabilized by a hat ring172. A reinforcing ring174can be provided in the body164of the seal to prevent extrusion of the material due to high pressures or temperatures.

When the seats954and seat retainers953carrying the seals958,962,966and970are installed in the respective seat pockets955and retainer pockets957, the seal springs170of the seals are compressed between the respective opposing faces of the seats, seat retainers and pockets. In other words, when installed, each seal spring170is pushing outward against the compression, creating initial upstream fluid seals in the retainer upstream seals958and seat upstream seals962using spring force to push the seal lips168of the upstream seals against the associated opposing faces, and creating initial downstream fluid seals in the retainer downstream seals966and seat downstream seals970using spring force to push the seal lips of the downstream seals against the associated opposed faces. When pressure from the pressurized fluid118in the gate valve reaches the concave surfaces166of seals958,962,966and970, the force from the pressure is added to the spring force from the seal springs170to increasingly press the seal lips168of each respective seal against the respective faces of the seats, seat retainers and pockets, thereby preventing leakage of pressure or fluid. These spring energized seals, however, work only when the pressure is applied to the concave surface side of the seals958,962,966and970; otherwise the pressure and fluid can leak by the seal relatively easily. Thus, to provide a bi-directional seal from pressure coming from either direction of the valve body, the orientation of the concave surfaces166along the path of the outer interface is reversed between the retainer upstream seal958and the retainer downstream seal966; e.g., in the embodiment ofFIG.14, the concave surfaces point away from one another along the path of the outer interface. Similarly, the orientation of the concave surfaces166along the path of the inner interface is reversed between the seat upstream seal962and the seat downstream seal970; e.g., in the embodiment ofFIG.14the concave surfaces166point away from one another along the path of the inner interface.

In the embodiment ofFIG.14, when there is higher pressure in the bore904versus the cavity908, the pressure will push fluid from the flow bore along the path of the outer interface between the retainer pocket955and the seat retainer953until it encounters the concave surface166of the retainer upstream seal958facing into the direction of this flow from the flow bore and (provided the retainer upstream seal and relevant opposing faces960,961are in good condition) thereby activating the retainer upstream seal to stop fluid leakage along the outer interface into the cavity908. However, if the retainer upstream seal958or opposing faces are worn or damaged, the pressurized fluid will leak past the retainer upstream seal toward the cavity908, flow along the outer interface and leak past the retainer downstream seal966and into the cavity, because the concave surface166of the retainer downstream seal is oriented in the reversed direction for this flow, i.e., facing away from the direction of flow, and thus will not activate. Similarly, higher pressure in the flow bore904will push fluid along the path of the inner interface between the seat pocket957and the seat954until it encounters the concave surface166of the seat upstream seal962facing into the direction of flow from the flow bore, and (provided the seat upstream seal and relevant opposing faces963,964are in good condition) thereby activating the seat upstream seal to stop fluid leakage along the inner interface into the cavity908. However, if the seat upstream seal962or opposing faces are worn or damaged, pressurized fluid will leak past the seat upstream seal toward the cavity908, flow along the inner interface and leak past the seat downstream seal970and into the cavity, because the concave surface166of the seat downstream seal is oriented in the reversed direction for this flow, i.e., facing away from the direction of flow, and thus will not activate.

On the other hand, when there is higher pressure in the cavity908versus the flow bore904, the pressure will push fluid from the cavity along the path of the outer interface between the retainer pocket955and the seat retainer953until it encounters the concave surface166of the retainer downstream seal966facing into the direction of this flow from the cavity, and (provided the retainer downstream seal and relevant opposing faces967,968are in good condition) thereby activating the retainer downstream seal to stop fluid leakage along the outer interface into the flow bore904. However, if the retainer downstream seal966or opposing faces are worn or damaged, pressurized fluid will leak past the retainer downstream seal toward the flow bore904, flow along the outer interface and leak past the retainer upstream seal958and into the flow bore, because the concave surface166of the retainer upstream seal is oriented in the reversed direction for this flow, i.e., facing away from the direction of flow, and thus will not activate. Similarly, higher pressure from the cavity908will push fluid along the path of the inner interface between the seat pocket957and the seat954until it encounters the concave surface166of the seat downstream seal970facing into the flow from the cavity, and (provided the seat downstream seal and relevant opposing faces971,972are in good condition) thereby activating the seat downstream seal to stop leakage along the inner interface into the flow bore904. However, if the seat downstream seal970or opposing faces are worn or damaged, pressurized fluid will leak past the seat downstream seal towards the flow bore904, flow along the inner interface and leak past the seat upstream seal962and flow into the flow bore, because the concave surface166of the seat upstream seal is oriented in the reversed direction for this flow, i.e., facing away for the direction of flow, and thus will not activate.

Each respective dual seat assembly952even further comprises a respective annular retainer spring956disposed in a retainer spring pocket formed on the axial outward facing ends (i.e., facing away from the gate912) of the seat retainer953. When the seat retainer953is pushed into the retainer pocket955, the retainer spring956is compressed between the inward facing end of the retainer pocket and the outward facing end of the retainer spring pocket, thus biasing the seat retainer (and also the seat954carried by the seat retainer) axially inward against the gate912. This inward biasing of the respective retainers953and seats954allows the inward facing ends of the seats to maintain contact with the respective surfaces of the gate912as it moves between the open and closed position.

The gate valve900having dual seat assemblies952on each side of the gate912provides several advantages compared to gate valves having a single seat assembly on each side of the gate (e.g., seat assembly152on gate valve100). The dual seat assembly952including the seat retainer953and the seat954has two replaceable components that can be selectively individually replaced depending on their individual state of wear or damage. Thus, for example, if the seat954becomes worn or damaged due to contact with the gate912, the seat can be replaced while the seat retainer953is retained. Conversely, if the seat retainer953becomes worn or damaged, the seat retainer can be replaced while the seat954is retained. As best seen inFIG.13, each of the replaceable dual seat components953,954is thinner (i.e., in the axial direction) than a single seat having the same overall thickness, thus each dual seat component will contain less material than the single seat, and thus may be less expensive. For example, inFIG.13, seat954has a width denoted DA, seat retainer953has a width denoted DB, and a single seat spanning the same distance between the valve body902and gate912would have a width of DC, where DA<DCand DB<DC.

Further, in the gate valve900having dual seat assemblies952, the bending moment exerted on the seals958,962at the base of each component953,954by the sliding force of the gate912will be less that the bending moment exerted on the seals at the base of a single component seat of the same overall width. For example, inFIG.13, the sliding force of the gate912against the seat954, denoted FG, will produce a bending moment of FG×DEat seat upstream seal962, and FG×DFat retainer upstream seal958, whereas in a single seat assembly, the bending moment at the single upstream seal having the same overall width (e.g.,158) would be FG×DG, where FG×DE<FG×DGand FG×DF<FG×DG. The reduction of bending moment provided by the dual seat assemblies952is believed to reduce deformation and wear on the seals958and962, this providing improvements in service life and reduced leakage.

It will be appreciated by those skilled in the art having the benefit of this disclosure that this gate valve and seat for a gate valve provides a better wear resistance, less maintenance and increased safety in comparison to conventional gate valves. It should be understood that the drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to be limiting to the particular forms and examples disclosed. On the contrary, included are any further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments apparent to those of ordinary skill in the art, without departing from the spirit and scope hereof, as defined by the following claims. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.