Dynamic Slab Gate Valves

In one instance, a dynamic slab gate valve is disclosed for use in controlling fluid flow through pipelines and other tubulars, wherein the dynamic slab gate valve has a dynamic seat assembly and a dynamic skirt assembly. The dynamic seat assembly is urged toward a gate of the dynamic slab gate valve by an energizer to maintain a seal between a seat and the gate. The dynamic skirt assembly is urged toward the gate of the dynamic slab gate valve by an energizer to maintain a seal with the gate. Improved seals are provided. Other valves are disclosed herein.

TECHNICAL FIELD

This application is directed, in general, to valves for use in fluid transfer applications, and more specifically to dynamic slab gates valves, which may be used in oil and gas applications.

BACKGROUND

The following discussion of the background is intended to facilitate an understanding of the present disclosure only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge at the priority date of the application.

Gate valves are used to control the transfer of fluids in tubing and pipelines. Specifically, gate valves are used to stop and start the flow of fluids in a downstream direction. Gate valves are commonly used in the oil and gas industry to control the flow of various fluids such as production fluids, water, fracking fluids, and other fluids used in drilling, operating, and maintaining oil and gas wells.

Gate valves generally operate by actuation of an internal gate, which in one position has an opening to allow upstream fluids to flow through the valve and in a downstream direction and a second position which blocks flow through the valve thereby preventing transfer of fluid in a downstream direction. While gate valves have been in existence for a long time, improvements are still desired.

SUMMARY

According to an illustrative embodiment, a slab gate valve includes a valve body formed with a through-bore in a first direction and formed with a gate cavity in a second direction, which is orthogonal to the first direction. The slab gate valve further includes a slab gate having a first portion and a second portion, wherein the slab gate has a first side and a second side. The gate cavity is sized and configured to receive the slab gate. The first portion of the slab gate is sized and configured to occlude the through-bore when the slab gate is in a closed position. The second portion of the slab gate valve is formed with a flow aperture for allowing flow therethrough when the slab gate is in an open position. At least one stem is coupled to the slab gate for selectively moving the slab gate between the open position and the closed position.

The slab gate valve further includes a downstroke lubricant cavity formed in a portion of the valve body; a first seat cavity formed in the valve body proximate a first intersection of the through-bore and the gate cavity on a first side of the first intersection; and a second seat cavity formed in the valve body proximate a second intersection of the through-bore and the gate cavity on a second side of the second intersection. The slab gate valve also includes a first dynamic seat assembly disposed in the first seat cavity, a second dynamic seat assembly disposed in the second seat cavity, a first dynamic skirt disposed adjacent to the first side of the slab gate and disposed between the first seat cavity and the downstroke lubricant cavity, and a second dynamic skirt disposed adjacent to the second side of the slab gate and disposed between the second seat cavity and the downstroke lubricant cavity.

In one illustrative embodiment, the first dynamic seat assembly in the slab gate valve of the previous two paragraphs may include a first cylindrical seat having a first side and a second side, wherein the second side is adjacent to the first side of the slab gate. A first debris ring slot is formed on an inner portion of the first cylindrical seat. The first dynamic seat assembly may also include a debris ring proximate the first side of the first cylindrical seat and disposed at least partially within the first debris ring slot. The first cylindrical seat may be formed with a seat energizer cavity proximate the first side of the first cylindrical seat. The first dynamic seat assembly may also include a seat energizer disposed at least partially in the energizer cavity and operable to urge the first dynamic seat toward the slab gate.

According to another illustrative embodiment, a slab gate valve includes a valve body formed with a through-bore in a first direction and formed with a gate cavity in a second direction orthogonal to the first direction and a slab gate having a first portion and a second portion, wherein the slab gate has a first side and a second side. The gate cavity is sized and configured to receive the slab gate. The first portion of the slab gate is sized and configured to occlude the through-bore when the slab gate is in a closed position. The second portion of the slab gate valve is formed with a flow aperture for allowing flow therethrough when the slab gate is in an open position. The slab gate valve also includes at least one stem coupled to the slab gate for selectively moving the slab gate between the open position and the closed position; a downstroke lubricant cavity formed in a portion of the valve body; at least one seat cavity formed in the valve body proximate an intersection of the through-bore and the gate cavity; and at least one dynamic seat assembly disposed in the at least one seat cavity.

According to still another illustrative embodiment, a slab gate valve includes a valve body formed with a through-bore in a first direction and formed with a gate cavity in a second direction orthogonal to the first direction and a slab gate having a first portion and a second portion, wherein the slab gate has a first side and a second side. The gate cavity is sized and configured to receive the slab gate. The first portion of the slab gate is sized and configured to occlude the through-bore when the slab gate is in a closed position. The second portion of the slab gate is formed with a flow aperture for allowing flow therethrough when the slab gate is in an open position. The slab gate valve further includes at least one stem coupled to the slab gate for selectively moving the slab gate between the open position and the closed position; a downstroke lubricant cavity formed in a portion of the valve body; and at least one dynamic skirt disposed adjacent to the slab gate and between the slab gate and the downstroke lubricant cavity. Other valves and embodiments are presented further below.

DETAILED DESCRIPTION

In one exemplary embodiment, a dynamic gate valve has a valve body with a through-bore running the length of the gate valve. The through-bore being, typically, of circular cross section. The ends of the gate valve are connected to upstream and downstream tubulars, with fluid entering the gate valve from the upstream side and exiting the gate valve from the downstream side.

Flow is opened or closed by a gate. The gate is generally a slab with an opening in one area and a solid surface in another area. The gate resides within a cavity which bisects the through-bore and is able to be moved from an open position, in which the opening of the gate is in line with the through-bore, and a closed position, in which the solid surface of the gate blocks flow through the through-bore.

The gate is a dynamic gate that can translate a distance in the direction of the through-bore in response to fluid pressures exerted against the gate surface. The dynamic gate valve also has a dynamic skirt, which provides a seal between fluid flow areas of the valve and lubricated areas (or lubricated reservoirs or cavities) of the valve. The dynamic skirt, therefore, reduces cross-flow between through-bore fluids and lubricants, thereby reducing contamination of lubricants and loss of lubricants. The dynamic skirt is biased by a skirt energizer, so that the dynamic skirt is biased toward the gate to achieve a seal with a gate surface and to move in response to gate movement.

The dynamic gate valve may also include a dynamic seat, which provides a seal between the gate and the through-bore to prevent through bore fluid from flowing into operational areas of the valve. Part of the seal formed by the seat includes contact of a seat surface with the gate, which prevents through-bore fluid from flowing into lubrication areas. The seat is biased by an energizer toward the gate surfaces to increase the quality of this seal. In addition, the biasing force of the energizer results in movement of the seat toward the gate as the gate translates in the direction of the through-bore. Thereby, the seat dynamically moves with the movement of the gate, which moves in response to fluid pressures, to maintain the seal between the seat and the gate.

Referring now to the figures and primarily toFIGS.1-4, an illustrative embodiment of a slab gate valve100is presented. The slab gate valve100has a through-bore104, which is a circular bore through the length of a valve body108, for allowing a fluid flow therethrough as desired. The through-bore104is oriented along the length of the valve body108in a first direction112. The slab gate valve100is coupled to a pipe or other tubing, through which fluid may flow in the first direction112with a first flange116and a second flange120. A pipe or other tubing is connected to the first flange116and the second flange120with bolts or studs using a plurality of bolt holes124, so that fluid may flow through the through-bore104in the first direction112. The valve body may be connected to a pipe via any attachment technique or device including, inter alia, the following: Welded Connection, Studded Connection, Hammer Union, Threaded Connection, Hub & Clamp Connection, and Collar Connection. The disclosure also includes a multi valve body comprising of one or more valves in a singular block body.

It should be noted that slab gate valve100may be bi-directional, but for convenience, is presented with flow in a single direction. A gasket pocket152is disposed within the end of each flange116and120so that a gasket may be inserted into the gasket pocket152to provide a fluid seal between the first flange116or the second flange120and an upstream or downstream pipe or tubing connection, e.g., a mating flange.

An upper bonnet128and a lower bonnet132are located on an upper side and a lower side, respectively, of the valve body108. All relative directions, e.g., “upper” and “lower,” are for the orientation shown in the figures. The upper bonnet128and the lower bonnet132are used to attach and contain a portion of a gate assembly134within the valve body108. The gate assembly134is formed of a gate136, an upper stem140, and a lower stem142. The upper bonnet128and the lower bonnet132are coupled to the valve body108with studs or bolts using a plurality of bolt holes144. The upper stem140and the lower stem142extend from the centers of the upper and lower ends of the upper bonnet128and the lower bonnet132, respectively. The upper stem140and the lower stem142are used to actuate the gate assembly134between an open and closed position.

A gate cavity156is a cavity within the valve body108that is oriented in a second direction114and that is perpendicular to and transects the through-bore104. The gate cavity156is sized and configured to receive a gate assembly134, and the gate cavity156may be further sized and configured to receive a dynamic shield assembly and may be optimized to minimize or reduce the volume of lubricant required. An upstroke lubricant cavity164and a downstroke lubricant cavity168are partially formed by cutouts from the valve body108at the upper and lower ends of the gate cavity156. The upstroke lubricant cavity164and the downstroke lubricant cavity168are also partially formed by cutouts within the upper bonnet128and the lower bonnet132, respectively. When the upper bonnet128and the lower bonnet132are assembled onto the valve body108, the cutouts within the upper bonnet128and the valve body108and the cutouts within the lower bonnet128and the valve body108align to form the upstroke lubricant cavity164and the downstroke lubricant cavity168, respectively. The connection between the upper bonnet128and the valve body108is sealed from fluid flow by an upper bonnet gasket130. Likewise, the connection between the lower bonnet132and the valve body108is sealed from fluid flow by a lower bonnet gasket138. The lower bonnet gasket138and the upper bonnet gasket130are made from suitable gasket material, such as any compressible material, for example any of the NBR type rubbers. Other examples include metallic, non-elastomeric materials (PTFE, MPTFE, PEEK, Graphite/re-enforced Graphite, or any combination of the above. Those skilled in the art will appreciate that other materials may be used as well.

The through-bore has a diameter148, which is of sufficient size to allow for the desired flow through slab gate valve100. In one embodiment the diameter148is in the range of 1 13/16″ thru 7 1/16″. Those skilled in the art will appreciate that other sizes may be used.

The upstream seat pocket172and the downstream seat pocket176are cavities within the valve body108within the through-bore104at the intersection of the through-bore104and the gate cavity156. The upstream seat pocket172and the downstream seat pocket176are both configured to receive a dynamic seat assembly180, which provides fluid and pressure seals between the seat assemblies180and the gate assembly134. The upstream seat pocket172and the downstream seat pocket176are annular rings that are concentric with the through-bore104.

As the slab gate valve100is operated between an open and a closed position, the gate assembly134moves back and forth along the second direction114within the gate cavity156. This movement results in movement of the upper end of the gate156and the upper stem140through upstroke lubrication cavity164and movement of the lower end of gate156and the lower stem142through downstroke lubrication cavity168. In the course of this movement, the gate156, the upper stem140, and the lower stem142are lubricated by lubricants within upstroke lubrication cavity164and downstroke lubrication cavity168. A dynamic skirt assembly244, which is discussed in more detail below, acts as a barrier to prevent excessive exchange of lubricants and fluids between the through-bore104and the downstroke lubrication cavity168and the upstroke lubrication cavity164during the opening and closing process.

Referring now primarily toFIG.5, an illustrative embodiment of the gate assembly134is presented. The gate assembly134contains the gate136, the upper stem140, and the lower stem142. The gate136has a closed portion184and an open portion188. The open portion188contains a circular cutout or flow aperture190to allow for flow through the gate136. When the gate136is in the open position, the open portion188is in line with and concentric to the through-bore104. The closed portion184is solid to prevent flow through the gate136. When the gate136is installed into the slab gate valve, such as slab gate valve100, and is in the closed position, the closed portion184of gate136is in line with and blocks flow though the through-bore104of the slab gate valve100. When gate136is installed into a valve, such as slab gate valve100, and is in the open position, the open portion188of gate136is in line with and allows for flow though the through-bore of the slab gate valve100. In the depicted embodiment, the closed portion184is depicted as being above the open portion188. In other embodiments, this relationship between the closed portion184and the open portion188can be reversed so that closed portion184is below open portion188.

An upper end of the gate136is configured to receive the upper stem140. Shoulders192may be formed on the upper end of the gate136. The shoulders192are configured to form a t-slot for receiving a portion of the upper stem140, namely a tee196. The lower end of the upper stem140has the tee196. The upper stem140is coupled to and captured by the gate136by sliding the tee196of the upper stem140into the tee slot194formed by the shoulders192. This configuration allows for the gate136to be captured by the upper stem140so that the movement of the upper stem140within slab gate valve100in the first direction112of the gate cavity156causes the gate136to move along with the upper stem140, therefore allowing upper stem140to be used to move the gate136between a closed and open position within the slab gate valve100.

The lower end of the gate136is similarly configured with shoulders200forming a tee slot202for receiving a tee204. In this way the gate136receives the lower stem142, so that the lower stem142may also be used to move the gate136between and open and closed position within a valve.

While, in this embodiment the tee and t-slot connection between gate136and upper stem140and gate136and lower stem142is formed with the tee portion on the upper stem140and on the lower stem142and the t-slot portions on the gate136, in other embodiments this relationship can be reversed so that the tee portions are formed on the gate136and the t-slot portions are formed on the upper stem140and the lower stem142. In other embodiments, the gate assembly134has only one stem connection, which may be either an upper stem or lower stem.

The tee196and the tee204allow for movement in the first direction112(flow direction) of the gate136relative to the upper stem140and the lower stem142to accommodate for pressures applied to the gate136when the gate136is in use in a valve, such as slab gate valve100.

Referring now primarily toFIGS.6and7, an illustrative embodiment of the dynamic seat assembly180of a slab gate valve100is presented.FIG.6depicts a perspective view with a portion in cross section of the dynamic seat assembly180.FIG.7depicts a cross sectional view of the dynamic seat assembly180taken at the cross-section location228(FIG.6). When installed within the slab gate valve100, the dynamic seat assemblies180are disposed within an upstream seat pocket172and a downstream seat pocket176.

The embodiment of the dynamic seat assembly180depicted inFIGS.6and7has a seat208, a first debris ring212, a second debris ring216, a seat seal220, and a seat energizer224. The seat208fits with a seal pocket (see172and176inFIG.4). The first debris ring212may be disposed at least partially in the first debris ring slot or shoulder226. The second debris ring216may be disposed at least partially within a second debris ring shoulder or slot230. The seat energizer224may be disposed at least partially in a seat energizer slot of the shoulder232, which also may be referred to as a seat energizer cavity, and may be adjacent to a portion of the first debris ring212. The seat208has a cylindrical body with an inner through-bore. The seat208has an inner portion235and outer portion236, or perimeter.

The first debris ring212and the second debris ring216each provide a debris seal between the valve body108and the seat208. The first debris ring212is perforated by the perforations232to allow pressure through the first debris ring212, while preventing large particles from passing through the seal. The perforations may be in the range of 063 inches or smaller and may be formed by machining via drill, waterjet, laser cutter, or other technique. The second debris ring216may have no perforations and may be sized to maintain a space between the seat208outside diameter and the valve body seat pocket176ID. The space is designed to prevent even smaller material from entering the seal area220/237. The gap may be in the range of 0.003″ or smaller.

In addition, fluid may flow past first debris ring212and the second debris ring216in the space between first debris ring212and the second debris ring216and the valve body108or seat208. The first debris ring212or the second debris ring216can serve a dual role as a bearing and as a device to prevent debris from reaching seat seal220. In some embodiments, the dynamic seat assembly180may have only one debris ring. In some embodiments, the first debris ring212and the second debris ring216are not perforated.

The first debris ring212and second debris ring216are configured to exclude the passage particles and debris of a certain size past the first debris ring212or the second debris ring216. The minimum size of the particles excluded by the first debris ring212is larger than that excluded by the second debris ring216. Therefore, the first debris ring212acts as a first pass particulate filter and the second debris ring216acts as a second pass particulate filter, which removes finer particles than are removed by the first debris ring212. In some embodiments the first debris ring212prevents debris in fluids that are flowing through the through-bore104that are 0.063″ in diameter or larger from passing the first debris ring212. In some embodiments, the second debris ring216prevents debris in fluids that are flowing through the through-bore104that are 0.002″-0.003″ in diameter from passing the second debris ring. Those skilled in the art will appreciate that other sizes of apertures may be used.

The first debris ring212and second debris ring216may be made from many materials, e.g., PEEK (polyetheretherketone) material (or other suitable plastic) or metals. In one embodiment, the debris rings212,216are made from graphite or re-enforced graphite.

The connection between the dynamic seat assembly180and the valve body108is sealed, at least in part, from fluid and gas flow by the seat seal220. The seat seal220is disposed within a seat seal cavity237, which is formed in an exterior or outer perimeter of the seat208. When the dynamic seat assembly180is installed within the upstream seat pocket172(FIG.4) or the downstream seat pocket176, the seat seal forms a liquid and gas tight seal to prevent or at least substantially restrict fluid and gas flow.

The seat seal220can be either non-elastomeric material like polytetrafluoroethylene (PTFE), modified polytetrafluoroethylene (MPTFE), polyetheretherketone (PEEK), graphite/re-enforced graphite, or metal or a combination or made of an elastomer like that used for O-rings, e.g., hydrogenated nitrile butadiene rubber (HNBR), nitrile butadiene rubber (NBR), fluo Kohlenstoff material (FKM), perfluorelastomers (FFKM), etc. The seat seal220, the first debris ring212, the and second debris ring216can vary with different applications. In one embodiment, the seat seal220is about ¼ inch in width, 9 inches in diameter, and ⅛ deep.

The dynamic seat assembly180also may include a tooling cutout240. The tooling cutout240allows for a tool to be inserted into the tooling cutout240for prying the dynamic seat assembly180from the upstream seat pocket172or the downstream seat pocket176.

Referring now primarily toFIG.8, an illustrative embodiment of a dynamic skirt assembly244of a dynamic slab gate valve, such as slab gate valve100is presented. The dynamic skirt assembly244may include a first lubricant guide248, and may include a second lubricant guide252, a skirt plate256, and a skirt energizer260. The skirt plate256has a first side264that when assembled is closest to the gate136(FIG.3) and has a second side268that when assembled is furthest from the gate136, when installed into slab gate valve100. The first side264of the skirt plate256, when installed in slab gate valve100, faces the gate136within the valve to provide a sealed surface between the skirt plate256and the gate136to prevent excessive grease and fluid flow between such seal. The second side268of the skirt plate256faces a portion of the valve body104(seeFIG.3.). The skirt energizer260is coupled to the skirt plate256on the second side268. In the depicted embodiment, this coupling may be made by a spot weld272. Other coupling methods, such as screws, weld-stud, or a nut and bolt or other fasteners may be used for this coupling. The skirt energizer260may be coupled vertically (for orientation shown) as shown inFIG.8or horizontally (i.e., a third direction115inFIG.3). The first lubricant guide248and the second lubricant guide252extend from the second side268of the skirt plate256and are shaped to conform with the shape of lubricant pockets of a valve, such as downstroke lubricant cavity168ofFIG.2. The first lubricant guide248and the second lubricant guide252have openings276and280, respectively to allow lubrication, such as grease to flow through the openings276and280. The lubricant guide248,252may be welded, bolted, mechanically attached, or formed directly to the skirt plate256. A lower portion of the skirt plate256may be formed with or without a cutout258, e.g., an arcuate cutout as shown.

FIGS.9,10A,10B, and10Cdepict the operation of a representative embodiment of a dynamic skirt assembly244of a slab gate valve100. As depicted in the proceeding figures, the dynamic skirt assembly244is located within the slab gate valve100and in particular is partially disposed between the gate136and a valve body108and partially disposed between a lower stem142and the valve body108. A portion of the dynamic skirt assembly244is also disposed within the downstroke lubricant cavity168, the downstroke lubricant cavity168being formed from cavities in the valve body108and in a lower bonnet132and, when the slab gate valve100is in use, being filled with a lubricant, such as grease. The dynamic skirt assembly244is comprised of the skirt plate256and a skirt energizer260, with the side of the dynamic skirt assembly244having the skirt energizer260facing the valve body108so that the skirt energizer260is in contact with the valve body108and the skirt energizer260biases the dynamic skirt assembly244away from the valve body108, therefore, creating cavity284between the skirt plate256and the valve body108. The force of the skirt energizer260also biases the other side of the skirt plate256toward the gate136and the lower stem142, thereby creating a seal between the skirt plate256and the gate136or the lower stem142. In one illustrative embodiment the skirt energizer260is a metal spring formed with angled ends that have a free position lifted off the skirt plate256. Other types of energizers may be used or wire-type (coiled or bent) compression, conical, leaf, Belleville, grater, disc type energizers that may be made from rubber, plastic, metal, or another material.

As depicted inFIG.9, fluid pressure in the through-bore104creates a pressure force against the upstream side of the gate136. As described above in relation toFIG.5, the connection between the gate136and lower stem142and the gate136and the upper stem140is a dynamic connection where the gate136can translate in the first direction112along the length of the through-bore104in response to pressure forces from fluids within the through-bore104. Therefore, when the gate136is in the closed position, upstream fluid pressure pushes against the gate136, which results in translation of the gate136in the first direction112, as the tee slides relative to the associated slot (seeFIG.5).

The dynamic skirt assembly244is intended to provide a good seal between the fluid and debris flowing through the through-bore104and the lubricant located in the downstroke lubricant cavity168. A poor seal between the gate136and the skirt plate256or between the lower stem142and the skirt plate256results in the entry of through-bore fluids and debris into the downstroke lubricant cavity168and for the loss of lubricant into the through-bore104, both of which result in decreased efficiency and operation of the slab gate valve100. The potential for such to happen is particularly an issue during opening and closing operations of the slab gate valve100.

Referring now primarily toFIGS.10A,10B, and10C, an illustrative embodiment of a slab gate valve in various positions (an open position, a partially open position, and a closed position, respectively) is presented. When the gate136is in the open position, fluid is flowing through the through-bore104and the open portion188of the gate136. As the gate136is moved toward a closed position (see, e.g., the intermediate position inFIG.10B), the open portion188of the gate136moves lower into the gate cavity156and eventually, once the closed position (see, e.g.,FIG.10C) is reached, is totally located below the through-bore104and is not in fluid communication with the through-bore104. However, during the closing process, fluid that is located within the open portion188of the gate136is trapped within the opening188and remains trapped within the open portion188when the gate136is in the closed position.

Without the skirt plate256in place as depicted inFIG.10C, the trapped fluid in the open portion188can commingle and mix with the lubricant located in the downstroke lubricant cavity168. This results in the introduction of through-bore fluids and debris into the downstroke lubricant cavity168, which contaminates and reduces the effectiveness of the lubricant. In addition, this results in the dilution and washout of lubricant from the downstroke lubricant cavity168, with lubricant moving into the open portion188, where the lubricant serves no effective purpose.

The existence of the skirt plate256assists in reducing the introduction of through-bore fluids and debris into the lubricant and the loss of lubricant from the lubricant pocket, or cavity. The skirt plate256provides a physical barrier to reduce or prevent this exchange.

However, to prevent this exchange and loss, a reliable seal between the skirt plate256and the gate136or the lower stem142is needed. Also, as discussed above, the gate136is a dynamic gate that moves in the first direction112in response to through-bore104fluid pressure. In this situation, a static skirt plate is inadequate. In the case of a static skirt plate, the skirt plate and a gate that make contact when fluid pressure is not applied to the gate do not make sufficient contact when fluid pressure causes the gate to move in the downstream direction.

The dynamic skirt assembly244addresses this deficiency. The skirt energizer260provides a biasing force between the valve body104and the skirt plate256. This biasing force results in a tighter, closer seal with the gate136. Furthermore, as the gate136is moved in the first direction112by fluid pressures, the biasing force of the skirt energizer260causes the skirt plate256to move in conjunction with the gate136, which in turn results in maintaining good contact and seal between the gate136and the skirt plate256. This, in turn, reduces the amount of through-bore fluid that enters the downstroke lubrication cavity168and the amount of lubricant that is lost into the open portion188of the gate136.

While in the depicted embodiments of the slab gate valve100, the open portion188of the gate136is above the closed portion184of the gate136, and the gate136is moved from an open position to a closed position by moving the gate136in the second direction114towards the downstroke lubricant cavity168. The direction of movement and the location of the open portion188relative to the closed portion184, as described, is for reference in relation to the embodiments as depicted. For example, a reversal of the relative positioning of the open portion188to the closed portion184and a reversal of the movement of the gate136from the open position to the closed position, would describe the embodiments depicted inFIGS.2and3, if the embodiments ofFIGS.2and3were inverted.

Referring now again primarily toFIG.9, which also depicts the function of the dynamic seat assembly180, the dynamic seat assemblies180are disposed within upstream seat pocket172and downstream seat pocket176of the slab gate valve100. As discussed above, the connection between the upper stem140and the gate136and the connection between the lower stem142and the gate136is a tee and t-slot type connection, which allows for the gate136to move in first direction112in response to fluid pressure of fluids within through-bore104. Contact between the gate136and the side of the dynamic seat assembly180that is adjacent to the gate136provides a seal to prevent through-bore fluids from transferring into the portions of the gate cavity that are above and below the level of the through-bore104within the valve body108, such as the upstroke lubricant cavity164and the downstroke lubricant cavity168. As discussed above fluid communication between the upstroke lubricant cavity164and the through-bore104or between the downstroke lubricant cavity168and the through-bore104results in loss of lubricant from the downstroke lubricant cavity168or the upstroke lubricant cavity164and in contamination of the fluids within through-bore104.

A static seat assembly, may provide such a seal when fluid pressure is not applied to a gate of valve. However, as the gate moves in response to fluid pressures, the seal between the gate and a static seat assembly is lost because the movement of the gate results in a gap between the gate and the seat assembly.

The use of the dynamic seat assembly180addresses this issue. The dynamic seat assembly180includes a seat energizer224, which, when installed in the slab gate valve100, is disposed between the seat208and the valve body108. The seat energizer224provides a biasing force that urges the seat208towards the gate136. The seat energizer may be any suitable energizer capable of providing a biasing force between the valve body108and the seat208. In some embodiments the energizer is a wave spring. Other types of energizers may be wire type (coiled or bent) compression, conical leaf, Belleville, grater, disc-type, which may all be made from rubber, plastic, material or another material.

This biasing force from the seat energizer may result in better seal quality between the seat208and the gate136. In addition, as the gate136is pushed in a downstream direction, the biasing force of the seat energizer224causes the seat208to move in conjunction with the gate136and, therefore, maintain a seal between the seat208and the gate136.

As used herein, “seal” means a substantial restriction of fluids or other substances; for example, in one example, a seal means less than 0.5% of fluid (gaseous, solid, or liquid) flowing gets by the seal.

Referring now primarily toFIG.11, a portion of an illustrative embodiment of a dynamic slab gate valve is shown. In the depicted embodiment, an alternative sealing configuration is depicted regarding the seal between the valve body108and the seat208. Like in the previously described embodiments, the seat assembly180is disposed within a seat pocket, which may be an upstream seat pocket172or downstream seat pocket176. The seat assembly180has a seat208, a first debris ring212, and a seat seal220. The seat seal220is disposed within the seat seal cavity237. The seat seal220is formed from an elastomeric material that forms a seal between the seat208and the valve body108. The contact seals between the seat seal220, the seat208, and the valve body108act as a liquid seal, a gas seal, and a pressure seal. The first debris ring212may have perforations232, which function as described above in relation to other embodiments to prevent the travel of debris from fluid flowing in the through-bore104. The seat assembly180also has a seat energizer224, which functions as described above to bias the seat208toward the gate136.

The seat assembly180also has a second debris ring216, a u-seal300, and a u-seal backer304. The u-seal300is formed from a material that does not allow gas permeation through the u-seal300. In some embodiments, the u-seal300is non-elastomeric. In some embodiments, the u-seal300is made from PTFE or PEEK. The u-seal300is formed so that a cross section of the u-seal300has a u-shaped profile, so that one side of the u-seal forms a cup or cavity. The u-seal300is installed within the seat assembly108so that the cup or cavity side of the u-seal faces the direction of fluid flow from the first debris ring212toward the second debris ring216. As fluid flows past the second debris ring216and to the u-seal300(left to right for the orientation shown), the cup or cavity portion of u-seal300is filled with fluids, which are under pressure. The fluid pressure is then exerted on the inside wall of the u-shaped seal300, which in turn causes the walls of the u-seal300to expand toward the valve body108and the seat208. The force of the fluid pressure pushing the walls of the u-seal300against the valve body108and the seat208results in a liquid and gas tight seal between the u-seal300and the valve body108and the u-seal300and the seat208. The higher the pressure that is exerted on the u-seal300, the tighter the seal becomes.

In the depicted illustrative embodiment, the second debris ring216is formed with a prong that is designed to fit within and conform to the cup or cavity shape of the u-seal300. In these embodiments, the prong of the second debris ring216prevents undesired deformation of the u-seal300when pressure is applied to the u-seal300or directs the proper expansion of the walls of the u-seal300when fluid pressure is applied within the cup or cavity portion of the u-seal300. In some embodiments, the second debris ring216is able to slide in response to fluid pressure so that the prong portion of the second debris ring216is forced into the cup or cavity portion of the u-seal300and makes contact with the u-seal to promote the proper expansion of the walls of the u-seal when pressure is applied, as described above.

The illustrative embodiment ofFIG.11may provide certain advantages. In particular, it is often necessary to form the seat seal220from an elastomeric material. This ensures that seat seal220can flex and conform to maintain a liquid and gas seal between the seat seal220and the valve body108and between the seat seal220and the seat180. However, the use of elastomeric seals in oil and gas operations potentially suffers from a fault. In particular, elastomeric materials that are suitable for forming the gas and liquid seals described are vulnerable to gas permeation. As gas pressure is applied to the elastomeric material, the gas is forced into and permeates through the elastomeric material. In applications in the oil and gas industry, the source of such gas can be gasses flowing through a pipeline or can be dissolved gasses present in fluids that are flowing through a pipeline.

In either case, since the seat seal220is often formed of an elastomeric material, while the seat seal220provides a reliable contact seal to prevent liquid and gas flow, it is subject to the possibility of gas flow through the seal220by permeation and release with pressure changes. This results in gas flow past the seat seal220and into gate cavity156, which is not desired.

On the other hand, many non-elastomeric materials, such as PTFE, PEEK, and other plastics, are not subject to gas permeation. By making u-seal300from such a non-elastomeric material the amount of gas that seat seal220is exposed to can be eliminated or decreased. The u-seal300may be made from a non-permeable material and is located upstream from the seat seal220. When pressure is applied on the insides of the walls of the u-seal within the cup or cavity portion of the u-seal300, the walls of the u-seal300are pushed tight against the valve body108and the seat208. This results in a seal that is able to prevent or reduce gas and fluid flow between these components. In addition, since the u-seal300is formed from a non-permeable material, gas is unable to flow through the body of the u-seal300or permeate the u-seal300. By this configuration, the amount of gas, which may permeate through the seat seal220or that contacts the seat seal220is reduced or eliminated.

The u-seal backer304is an elastomeric or non-elastomeric component that is located adjacent to u-seal300and between the u-seal300and the valve body108toward the seat seal220. In some embodiments, the u-seal backer304provides additional structural support to prevent undesired deformation of the u-seal300. In some embodiments, the u-seal backer provides a further backup seal to prevent fluid and gas flow past the u-shaped backer304. In some embodiments, u-seal backer304is omitted.

There are many examples of the various embodiments described herein. A number of examples also follow.

Example 1. A dynamic slab gate valve comprising:a valve body having a through bore through the length of the valve and formed with a gate cavity oriented transverse to and intersecting with the through bore;a gate located within the gate cavity operable to move linearly in the direction of the gate cavity between an open position and a closed position;a seat assembly disposed proximate the through bore, the seat assembly having a proximate side oriented toward the gate cavity so that the seat assembly contacts the gate when the gate is in the closed position and having a distal side on an opposite end from the proximate side;the seat assembly comprising at least one seal, a seat, and a seat energizer, wherein the seat energizer is located on the distal side of the seat assembly and biases the seat assembly away toward the gate; andwherein the seat assembly is sized and configured to translate in the direction of the through bore in response to pressure from the seat energizer.

Example 2. The dynamic slab gate valve of Example 1, further comprising at least one stem coupled to the gate wherein movement of the gate is actuated by movement of the at least one stem.

Example 3. The dynamic slab gate valve of Example 2, wherein the at least one stem comprises an upper stem and a lower stem wherein the upper stem is coupled to an upper side of the gate and the lower stem is coupled to a lower side of the gate.

Example 4. The dynamic slab gate valve of Example 3, wherein the gate can displace in the direction of the through bore relative to the upper stem and the lower stem in response to fluid pressures.

Example 5. The dynamic slab gate of Example 1, further comprising a lubricant pocket wherein a seal between the gate and the seat blocks fluid flow between the lubricant pocket and the through bore.

Example 6. The dynamic slab gate of Example 1, wherein the seat assembly further comprises at least one sediment blocker.

Example 7. The dynamic slab gate of Example 6, wherein the at least on sediment filter comprises a large sediment filter and a fine sediment filter.

Example 8. A dynamic slab gate valve, comprising:a valve body having a through bore through the length of the valve and a gate cavity oriented transverse to and bisecting the through bore;a gate located within the gate cavity operable to move in the direction of the gate cavity between an open position and a closed position;a stem connected to a proximate end of the gate;a lubricant pocket disposed within the valve body in fluid communication with at least a portion of the stem and a portion of the gate;a skirt assembly at least partially disposed between the valve body proximate the gate cavity and the gate and at least partially disposed between the stem and the lubricant pocket;wherein the skirt assembly comprises a skirt and a skirt biasing energizer;wherein the skirt biasing energizer biases the skirt away from a portion of the valve body and toward the gate.

Example 9. The dynamic slab gate valve of Example 8, wherein movement of the gate is actuated by movement of the stem.

Example 10. The dynamic slab gate valve of Example 8, wherein the gate can displace in the direction of the through bore relative to the stem.

Example 11. The dynamic slab gate valve of Example 10, wherein a seal between the skirt plate and the gate prevents fluid communication between the through bore and the lubricant pocket.

Example 12. The dynamic slab gate valve of Example 11, wherein the skirt biasing energizer biases the skirt plate toward the gate to maintain the seal between the skirt plate and the gate.

Example 13. A dynamic seat assembly for a gate valve comprising:at least one seal,a seat, anda biasing energizer,wherein, when installed in a gate valve, the biasing energizer biases the seat assembly toward a gate of the gate valve.

Example 14. The dynamic seat assembly of Example 13, wherein contact between the gate and the seat assembly reduces fluid communication between a through bore of the gate valve and a lubrication cavity of the gate valve.

Example 15. The dynamic seat assembly of Example 13, further comprising at least one sediment filter.

Example 16. The dynamic seat assembly of Example 15, wherein the at least one sediment filter comprises a large sediment filter and a fine sediment filter.

Example 17. A skirt assembly for a gate valve, comprising:a skirt plate, anda skirt energizer coupled to one side of the skirt plate,wherein, when installed in a gate valve, the skirt energizer biases the skirt plate toward a gate of a gate valve.

Example 18. The skirt assembly of Example 17, wherein the skirt assembly further comprises at least one lubricant guide coupled to the one side of the skirt plate.

Example 19. The skirt assembly of Example 17, wherein the skirt biasing energizer biases the skirt plate toward the gate when the gate translates in the direction of a through bore of the gate valve in response to fluid pressure.

Example 20. A dynamic slab gate valve comprising:a valve body having a through bore through the length of the valve and a gate cavity oriented transverse to and intersecting with the through bore;a gate located within the gate cavity operable to move in the direction of the gate cavity between an open position and a closed position;a seat assembly disposed proximate the through bore, the seat assembly having an inward side oriented toward the gate cavity so that the seat assembly contacts the gate when the gate is in the closed position;wherein the seat assembly comprises at least one seal, a seat, and a seat biasing energizer, and wherein the seat biasing energizer is located on an outboard side of the seat assembly and biases the seat assembly away toward the gate;wherein the seat assembly is configured to translate in the direction of the through bore in response to pressure from the biasing energizer.a stem connected to a proximate end of the gate;a lubricant pocket disposed within the valve body in fluid communication with at least a portion of the stem and a portion of the gate;a skirt assembly at least partially disposed between the valve body and the gate and at least partially disposed between the stem and the lubricant pocket;wherein the skirt assembly comprises a skirt and a skirt biasing energizer;wherein the skirt biasing energizer biases the skirt toward the gate.

Example 21. A dynamic slab gate valve comprising:a valve body formed with a through bore and a gate cavity orthogonal to the through bore;a gate disposed within the gave cavity, wherein the gate has a slab portion for halting flow in the through bore and an aperture portion for allowing flow through the gate valve and onward through the through bore; andone or more dynamic features associated with the gate.

Example 22. The dynamic slab gate valve of Example 21, wherein the one or more dynamic features comprises a dynamic valve skirt.

Example 23. The dynamic slab gate valve of Example 21, wherein the one or more dynamic features comprises a dynamic seat assembly.

Example 23. The dynamic slab gate valve of Example 21, wherein the one or more dynamic features comprises a dynamic valve skirt and a dynamic seat assembly.

Example 24. The dynamic slab gate valve of Examples 1-7, 13-16, or 20-22, wherein the seat assembly further comprises a non-elastomeric u-seal, wherein the non-elastomeric u-seal is formed with a cross-sectional profile with a u or cup shape, and wherein the u-seal is disposed between the valve body and the seat and oriented so that fluid or pressure flow flows into the u or cup shape of the non-elastomeric u-seal.

Example 25. The dynamic slab gate valve of Example 23, wherein a wall portion of the non-elastomeric u-seal deforms to expand the u or cup shape of the non-elastomeric u-seal in response to fluid or gas pressure exerted within the u or cup shape of the non-elastomeric u-seal.

Example 26. The dynamic slab gate valve of Example 23, wherein the non-elastomeric u-seal is formed from PEET.

Example 27. The dynamic slab gate valve of Example 23, wherein the non-elastomeric u-seal is formed from PTFE.

Although the present invention and its advantages have been disclosed in the context of certain illustrative, non-limiting embodiments, it should be understood that various changes, substitutions, permutations, and alterations can be made without departing from the scope of the invention as defined by the claims. It will be appreciated that any feature that is described in a connection to any one embodiment may also be applicable to any other embodiment.