Patent Description:
Stems used to connect an actuator to a gate are often match drilled. However, match drilled stems bear both a thrust load and a torque load. When an overtorque condition occurs the stem can be damaged requiring the entire gate to be taken off-line for a new stem to be used. Thus a system and method is needed to isolate the torque load and the thrust load. A further method is needed to prevent damage to the stem when overtorque occurs. A further need exists whereby replacement stems can be pre-manufactured and shipped when a stem is damaged and needs to be replaced.

The general purpose of the systems and methods disclosed herein is to provide an engineered solution to resolve stem connection problems in gate valves. Specifically, a coupler couples a first stem configured to bear a thrust load and a second stem configured to bear a torque load. In one non-limiting embodiment, the apparatus comprises a first stem, a second stem and a coupling assembly. In one embodiment, the positions of the stems within the coupler are secured by securing pins which pass through channels formed in the coupler, through the end of the respective stem to prevent the stem from twisting. In some embodiments the first stem is coupled to a valve gate and the second stem is coupled to an actuator. The overall apparatus is configured to isolate the thrust force exerted on the first stem and the torque force exerted on the second stem. In addition, when the valve is placed in an overtorque condition the securing pin is engineered to shear and fail before any other part of the coupling assembly is damaged. In addition, the coupling assembly is designed to allow replacement of damaged securing pins without taking the valve off-line by providing an access door to remove and replace the failed pin. This apparatus is designed to work in conjunction with a variety of existing valves, but it could also be included in conjunction with a coke drum deheading valve.

<CIT> discloses a fire hydrant having barrel sections connected together in an end-to-end relation by a frangible coupling ring which serves to protect the valve and its associated operating mechanisms from damage should the hydrant be struck by a motor vehicle or otherwise subjected to a severe horizontal stress. <CIT> discloses a valve stem coupling assembly according to the preamble of claim <NUM>.

<CIT> discloses a torque-reducing sleeve for a hydrant stem. A stem coupling for the hydrant includes an upper portion, a center of break-away features defined in the stem coupling and a lower portion. This disclosure relates to the protection of a hydrant during an accident involving damage to the hydrant. The upper stem can be configured to break away from the lower stem along with the portion of the hydrant exposed above ground, thereby allowing an upper portion of the hydrant to separate from a lower portion of the hydrant by a predictable, sacrificial failure of the coupling and other neighboring parts.

<CIT> relates to unheading valves that may be coupled to a coke drum, particularly at its top and/or bottom openings, wherein the valve functions to safely, effectively, and efficiently de-head or unhead the coke drum following the manufacture of coke, or other byproducts, and to facilitate the removal of coke during the decoking process. The de-header valve comprises a valve closure operably supported by a main body, wherein the valve closure is capable of being actuated to oscillate between an open and closed position with respect to an orifice of the de-header valve and the port of the coke drum.

Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment, but may refer to every embodiment.

One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment.

The features and advantages of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

In order to describe the manner in which the advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.

The present embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the disclosed invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed descriptions of the embodiments of the apparatus, as represented in <FIG> are not intended to limit the scope of the invention, as claimed, but are merely representative of present embodiments of the invention. Some embodiments comprise properly sizing the valve mechanisms with sufficient Safety Factors ("S. ") applied such that the valve mechanism is stronger from inside the valve outward to the actuator. Some embodiments comprise properly sizing actuation/operator to provide continual valve operation without excessive or undue thrust output. In some embodiments, in an overtorque condition, the invention comprises an easy to repair failure point that is external and accessible without major disassembly required. In some embodiments, in an overtorque condition, the invention comprises a design so that no major expense will be incurred to repair a valve. In some embodiments, in an overtorque condition, the invention comprises a design so that the valve will not be taken off-line to be repaired.

In the following description, numerous references will be made to actuators, gates and other valve structures which are not shown in detail in the figures. However, it should be understood that one of ordinary skill in the art and in possession of this disclosure, would readily understand how the present disclosure and existing valve structures can be incorporated.

Detailed references will now be made to the preferred embodiments of the disclosed invention, examples of which are illustrated in <FIG> which illustrate various views of a gate valve stem coupling assembly <NUM> in accordance with one or more embodiments of the invention.

In the typical delayed coking process, petroleum residues are fed to one or more coke drums where they are thermally cracked into light products and a solid residue-petroleum coke. Several different physical structures of petroleum coke may be produced. To produce the coke, a delayed coker feed originates from the crude oil supplied to the refinery and travels through a series of process members and finally empties into one of the coke drums used to manufacture coke. A basic refinery flow diagram is presented as <FIG>, with two coke drums shown.

Due to the shape of the coke drum, coke accumulates in the area near and attaches to the flanges or other members used to close off the opening of the coke drum during the manufacturing process. To empty the drum, the flanges or members must first be removed or relocated. In the case of a flanged system, once full, the coke drum is vented to atmospheric pressure and the top flange is unbolted and removed to enable placement of a hydraulic coke cutting apparatus. Removing or opening the bottom flange, or valve is commonly known as "de-heading" because it removes or breaks free the head of coke that accumulates at the surface of the flange or valve. Once the flanges are removed, the coke is removed from the drum by drilling a pilot hole from top to bottom of the coke bed using high pressure water jets. Following this, the main body of coke left in the coke drum is cut into fragments which fall out the bottom and into a collection bin, such as a bin on a rail cart, etc. The coke is then dewatered, crushed and sent to coke storage or a loading facility.

Although the present disclosure may be utilized in association with both top and bottom de-heading systems, or rather the de-heading system independent valve actuator system of the disclosed invention may be applicable and utilized on both the top and bottom openings of a coke drum, the following detailed description and preferred embodiments will be discussed in reference to a bottom de-heading system only. One ordinarily skilled in the art will recognize that the invention as explained and described herein for a coke drum bottom de-heading system may also be designed and used as a coke drum top de-heading system or to control flow in many other processes.

The present disclosure describes a valve system and method for unheading or de-heading a coke drum following the manufacture of coke therein. As the disclosed invention is especially adapted to be used in the coking process, the following discussion will relate specifically in this manufacturing area. It is foreseeable however, that the disclosed invention may be adapted to be an integral part of other manufacturing processes producing various elements or by products other than coke, and such processes should thus be considered within the scope of this application. For example, it is contemplated that the disclosed invention de-header system and de-header valves may be utilized within other critical service applications, such as inlet feed line isolation, blowdown isolation, fractionator isolation, and back warming.

<FIG> depicts, generally, a petroleum manufacturing and refinery process <NUM> having several elements and systems present (identified, but not discussed). In addition to these elements, petroleum manufacturing and refinery process <NUM> further comprises at least one coke drum and may include, as illustrated, a first and a second coke drum <NUM> and <NUM>, respectively, and de-header valves <NUM>-a and <NUM>-b attached thereto. In typical delayed coking operations, there are at least two coke drums in simultaneous operation so as to permit the ongoing, batch continuous, manufacture and refinery of petroleum as well as its coke byproduct.

<FIG> illustrates a non-limiting example of a de-heading system <NUM>. Coke drum de-heading system <NUM> comprises a de-header valve <NUM> that removably couples to a coke drum <NUM> using various means known in the art. De-header valve <NUM> typically couples to coke drum <NUM> or a spool at its flanged port or opening, much the same way a flanged head unit would be attached in prior related designs. De-header valve <NUM> is shown further attaching to upper and lower bonnets <NUM> and <NUM>, respectively.

The seat system of the de-header valve is designed to cleanly break the bond between the coke and the exposed surface of the valve closure at each stroke. The total thrust required for this action combined with the thrust required to overcome seating friction and inertia is carefully calculated and is accomplished by actuating the valve closure, thus causing it to relocate or transition from a closed to an open position.

<FIG> illustrates a non-limiting example of a sliding blind gate-type de-header valve <NUM>, according to one exemplary embodiment of the disclosed invention. Sliding blind gate-type de-header valve <NUM> comprises a main body <NUM> removably coupled to upper and lower bonnets <NUM> and <NUM>, each comprising upper and lower chambers <NUM> and <NUM>, respectively. Main body <NUM> comprises an opening or port <NUM> therein. Main body <NUM> removably couples to a complimentary flange portion and associated opening or port of a coke drum <NUM> or a spool, such that each opening is concentric and aligned with one another.

Sliding blind gate-type de-header valve <NUM> further comprises a valve closure in the form of a sliding blind or gate <NUM>. Some embodiments of a gate <NUM> may have an aperture therein that is capable of aligning with the opening in the coke drum and/or the opening in the spool, as well as the opening in the main body of the valve <NUM>. Alternatively, some gates may be solid, not utilizing an aperture therein, but rather utilizing a short gate that effectively opens the valve to allow coke from a coke drum <NUM> to fall through a valve when the shortened gate <NUM> is retracted into the upper bonnet <NUM>.

The gate <NUM> slides back and forth in a linear, bi-directional manner between means for supporting a valve closure, shown in this exemplary embodiment as seat support system <NUM>. Seat support system <NUM> may comprise any type of seating arrangement, including dual, independent seats, wherein the seats are both static, both floating or dynamic, or a combination of these. Seat support system <NUM> may alternatively comprise a single seat in support of valve closure <NUM>, wherein the seat may comprise a static or floating or dynamic seat. In another exemplary embodiment, means for supporting a valve closure may dispense with a seating system in favor of a support system built into main body <NUM>, such that one or more portions or components of main body <NUM> are selected and prepared to support valve closure <NUM>. In any event, seat support system may comprise a metal contact surface <NUM> that contacts and seals with a metal surface on valve closure <NUM>, wherein this contact seal is maintained during the coke manufacturing process.

Valve closure <NUM> is coupled to clevis <NUM>, which is turn coupled to valve stem <NUM>. Valve stem <NUM> may be utilized as an element of a system that functions to cause valve closure <NUM> to oscillate between an open and closed position. An actuator system <NUM> may be a hydraulically controlled power source contained within cylinder and that is capable of moving valve closure <NUM> through its linear, bi-directional cycle during a coking process, and may be utilized to de-head and re-head the coke drum <NUM>. Alternatively, an actuator system <NUM> may be an electrically controlled power source utilizing an electric actuator <NUM> that is capable of moving a valve closure via a transmission system <NUM> through its linear, bi-directional cycle during a coking process, and may be utilized to dehead and rehead the coke drum.

Detailed references will now be made to the preferred embodiments of the disclosed invention, examples of which are illustrated in <FIG>. In some embodiments coke drum de-heading system <NUM> is disclosed wherein a valve <NUM> comprising an actuator housing <NUM>, an upper bonnet <NUM>, a valve opening <NUM> and lower bonnet <NUM>. In some embodiments the valve <NUM> comprises a gate <NUM> configured to slide bi-directionally between the upper bonnet <NUM> and the lower bonnet <NUM>. In some embodiments the valve opening <NUM> comprises a blind or gate <NUM>. In some embodiments the valve <NUM> comprises a seat <NUM> configured to bias the valve against the gate <NUM> to isolate the valve opening <NUM> from the interior valve body. The gate-seat interface <NUM> is configured to seal in process and other contaminants and isolate the opening <NUM> from the valve interior of the body using a biasing mechanism <NUM> which biases the seat <NUM> against the gate <NUM>. In some embodiments the gate <NUM> is coupled to a second end of a second stem <NUM> by a clevis pin <NUM>, while the first end of the second stem is coupled to a coupler <NUM>. In some embodiments a first end of a first stem <NUM> is coupled to the coupler while the second end of the first stem is coupled to an actuator <NUM>. In some embodiments the actuator housing <NUM> may be a hollow housing configured to house other components. In some embodiments the actuator housing <NUM> may enclose interior components. In some embodiments the actuator housing <NUM> may partially enclose internal components. In some embodiments the actuator housing <NUM> may comprise an internal lubricant pooled in the actuator housing <NUM> and circulated around internal components to reduce friction caused by movement of internal components. In some embodiments the actuator housing <NUM> may be rigid and configured to provide structural support to internal components, as well as brace against a torque moment created during actuation by the operation of internal components. In some embodiments the internal components housed in the actuator housing <NUM> are internally lubricated, and the actuator housing <NUM> may have access ports which are not sealed. In some embodiments the actuator housing <NUM> may a power port <NUM> to power the actuator mechanism which may be powered pneumatically, electrically or mechanically.

In some embodiments the actuator housing <NUM> houses a coupling assembly <NUM> disposed within the actuator housing. In some embodiments the coupling assembly <NUM> comprises a coupler <NUM> which couples a first stem <NUM> and a second stem <NUM>. In some embodiments the actuator comprises an actuator motor <NUM> disposed on the actuator end of the actuator housing <NUM>. In some embodiments the actuator motor <NUM> is pneumatically powered. In some embodiments the actuator motor <NUM> is electrically powered. In some embodiments the actuator <NUM> is manually driven. In some embodiments the actuator housing <NUM> comprises a channel through which an indicator indicates the position of the nut housing. In some embodiments the indicator channel indicates the position of the gate in its stroke. In some embodiments the indicator channel will indicate to an operator whether the gate is open, partially open or closed. In some embodiments the actuator is configured to move the stem <NUM> or <NUM> bi-directionally through the valve <NUM> to cause a gate or blind <NUM> to move to an open or a closed direction.

Referring now to <FIG>, in some embodiments a gate valve stem coupling assembly <NUM> for isolating the torque load <NUM> from the thrust load <NUM> is disclsoed. In some embodiments the gate valve comprises an actuator housing <NUM>. In some embodiments the actuator housing <NUM> is disposed between an actuator <NUM> on a first end and a bonnet <NUM> on a second end. In some embodiments the actuator housing comprises a main channel running longitudinally through the length of the actuator housing <NUM>. In some embodiments the actuator housing <NUM> comprises a viewing aperture <NUM> formed in the side of the housing <NUM> which permits the physical inspection of the gate position, whether open or closed. In some embodiments the actuator housing <NUM> further comprises an access door <NUM> which permits access to the actuator housing's <NUM> main channel.

According to the claimed invention the coupling assembly comprises a first stem <NUM>. In some embodiments the first stem <NUM> is disposed in the actuator housing's <NUM> main channel. In some embodiments the first stem <NUM> is smooth and slides inside the actuator housing <NUM> as the first stem <NUM> is actuated to open or close a gate <NUM>. In some embodiments the first stem extends distally along the actuator housing's <NUM> longitudinal axis towards the bonnet <NUM>. In some embodiments the distal end of the first stem <NUM> is coupled to a gate <NUM>. In some embodiments the first stem is coupled to the gate <NUM> by a clevis connector. In some embodiments actuation of the gate exerts a thrust load <NUM> on the first stem <NUM>.

In some embodiments the distal end of the first stem <NUM> comprises a clevis pin. In some embodiments the proximal end of the first stem <NUM> comprises an insertion end. In some embodiments the proximal end of the first stem <NUM> is configured to receive a securing pin such as by a clevis. In some embodiments the first stem <NUM> insertion end is threaded and configured to screw into a threaded receiver. In some embodiments the proximal end of the first stem <NUM> is forked <NUM>. According to the claimed invention,
the coupler <NUM> end of the first stem <NUM> comprises a forked receiving portion <NUM> configured to receive the first pin at a variety of positions along in the fork <NUM>.

According to the claimed invention, the coupling assembly further comprises a second stem <NUM> disposed inside the actuator housing <NUM>. In some embodiments the second stem <NUM> is aligned with and extending opposite the proximal end of the first stem <NUM>. In some embodiments the second stem <NUM> is threaded. In some embodiments the distal end of the second stem <NUM> engages an actuator <NUM>. In some embodiment the actuator is a planetary roller screw which engages the threaded screw and actuates the coupling assembly <NUM>. In some embodiments actuation by the actuator <NUM> exerts a torque load <NUM> on the second stem.

In some embodiments the proximal end of the second stem <NUM> comprises an insertion end. In some embodiments the second stem <NUM> insertion end is threaded and configured to screw into a threaded receiver. In some embodiments the proximal end of the second stem <NUM> is configured to receive a securing pin such as by a clevis. In some embodiments the proximal end of the second stem <NUM> is forked <NUM>. In some embodiments the coupler <NUM> end of the second stem <NUM> comprises a forked receiving portion <NUM> configured to receive the second pin configured to receive the first pin at a variety of positions along in the fork <NUM>.

In some embodiments a coupler <NUM> is disposed inside the actuator housing <NUM>. According to the claimed invention, the coupler comprises a first stem receiving channel <NUM>. In some embodiments the first stem receiving channel is threaded. According to the claimed invention, the coupler <NUM> comprises a second stem receiving channel <NUM>. In some embodiments the second stem receiving channel <NUM> is threaded. According to the claimed invention, the first stem receiving channel <NUM> and the second stem receiving channel <NUM> are aligned. In some embodiments the threaded receiving end of the proximal end of the first stem <NUM> is screwed into the first stem receiving channel <NUM>. In some embodiments the threaded ends <NUM> and <NUM> are v-threads (aka vee threads). In some embodiments the threads comprise an <NUM> pitch to support the thrust load <NUM> placed there on. In some embodiments the second stem <NUM> is screwed into the second stem receiving channel <NUM>. In some embodiments the first stem <NUM> and the second stem <NUM> are coupled together when the first stem <NUM> and the second stem <NUM> are inserted into the coupler <NUM>.

According to the claimed invention, the first stem <NUM> is selectively coupled to the first stem receiving channel <NUM>, the second stem <NUM> is selectively coupled to the second stem receiving channel <NUM>, a first securing pin <NUM> is selectively inserted in the first pin receiving channel <NUM> so as to secure the orientation of the first stem <NUM> in the first stem receiving channel <NUM> and a second securing pin <NUM> is selectively inserted in the second receiving channel so as to secure the orientation of the second stem <NUM> in the stem receiving channel <NUM> wherein the first <NUM> and second <NUM> stem, first <NUM> and second <NUM> securing pin and coupler <NUM> comprise the coupling assembly <NUM>.

According to the claimed invention, the coupler <NUM> comprises a plurality of pin receiving channels <NUM>. In some embodiments the pin receiving channels <NUM> are orthogonal the coupler's <NUM> longitudinal axis. In some embodiments the channels are formed at an angle other than orthogonal the longitudinal axis. In some embodiments a pair of pin receiving channels <NUM> are aligned on opposite sides of the coupler <NUM> and configured to receive a pin <NUM>, <NUM> selectively inserted into the pin receiving channel <NUM>. In some embodiments the pin <NUM>, <NUM> can be inserted into the pin receiving channels <NUM> from either side of the coupler <NUM>. In some embodiments the threaded receiving channels <NUM> are threaded. In some embodiments, coupler <NUM> further comprises securing screws <NUM> which are screwed into the threaded pin receiving channels <NUM> to secure the securing pin <NUM>, <NUM> in the pin receiving channels <NUM>. In some embodiments the rotational orientation of first stem <NUM> and the rotational orientation of the second stem <NUM> are secured in place when the securing pin <NUM>, <NUM> are inserted into the pin receiving channels <NUM>.

In some embodiments the coupling assembly further comprises anti-rotation blocks <NUM>. In some embodiments anti-rotation blocks <NUM> are secured to the assembly by securing screws <NUM> which pass through anti-rotation blocks <NUM> before screwing into coupler <NUM>. In some embodiments blocks <NUM> sit in apertures <NUM>. In some embodiments as actuator <NUM> turns it exerts a torque on the assembly, anti-rotation blocks <NUM> stabilize the unit by pressing against the apertures <NUM> and prevent the torque force from being transferred past the coupler <NUM>. In some embodiments blocks <NUM> serve as wear pads. In some embodiments blocks <NUM> indicate the position of the <NUM> coupler and thus the position of the gate <NUM>, whether open or closed.

In some embodiments the coupling assembly <NUM> is assembled by hand wherein the first stem <NUM> is screwed into the first stem receiving channel <NUM> by hand to achieve the desired depth of engagement. The first securing pin <NUM> is then inserted into the pin receiving channel <NUM> intersecting the proximal end of the first stem <NUM> so as to prevent the first stem from rotating. In some embodiments the length of the forked receiving portion <NUM> of the proximal end of the first stem <NUM> is greater than the width of the securing pin <NUM> so that the securing pin <NUM> can be inserted when the first stem <NUM> is positioned at a variety of depths in the first stem receiving channel <NUM>.

In some embodiments the second stem <NUM> is screwed into the second stem receiving channel <NUM> by hand to achieve the desired depth of engagement. The second stem receiving pin <NUM> is then inserted into the pin receiving channel <NUM> intersecting the proximal end of the second stem <NUM> so as to prevent the second stem <NUM> from rotating. In some embodiments the length of the forked receiving portion <NUM> of the proximal end of the second stem <NUM> is greater than the width of the second securing pin <NUM> so that the securing pin <NUM> can be inserted when the second stem <NUM> is positioned at a variety of depths in the second stem receiving channel <NUM>.

In some embodiments the coupling of the first stem and the second stem isolates the torque <NUM> and thrust <NUM> loads created during actuation. In some embodiments isolating the respective loads protects either securing pin <NUM>, <NUM> from having to bear the both the tensile load, the shear and torsion forces. In some embodiments first securing pin <NUM> is isolated from the combined stresses created as the stem actuates. In some embodiments the first pin <NUM> is a shear pin and which resists torque only and operates in double shear.

In some embodiments the coupling vee threads handle only the tensile load due to the thrust generated by the acme screw.

According to the claimed invention, the coupler <NUM> is configured to couple the first stem <NUM> and the second stem <NUM> so as to isolate a torque load <NUM> and a thrust load <NUM>. Some embodiments apply the design protocol with Safety Factors applied such that the valve connections are stronger from the inside of the valve <NUM> outward to the actuator <NUM>. In some embodiments at least one of securing pin <NUM>, <NUM> comprise a torsional sear pin connection sized to exceed the actuator <NUM> maximum output (stronger than the second stem <NUM>). In some embodiments at least one of securing pins <NUM>, <NUM> will be designed to fail first, typically with a S. Referring to <FIG>, in some embodiments the stem <NUM> has a smaller diameter at slot <NUM> causing the pin to fail first, with pin diameters being equal, versus first stem <NUM> with same slot <NUM> (torque =F*d). In some embodiments at force <NUM> stem is always higher.

In some embodiments the valve stem is in an overtorque condition, the coupler assembly <NUM> is designed to fail securing pin <NUM> at end of second stem. In some embodiments where a securing pin has failed the pin is easily accessible through the access door <NUM>. In some embodiments, yoke slot <NUM> is used housing the anti-rotation blocks <NUM>. In some embodiments an access door is opened, the securing screws <NUM> removed and the damaged securing pin <NUM>, <NUM> is forced out of the pin receiving channel and a new pin <NUM>, <NUM> such as a standard dowl pin, is inserted in to the pin receiving channel. In some embodiments the failed pin should always be pin <NUM>, pin <NUM> should bin in good condition by may also be replaced to ensure new condition on repairing valve operator when replacing <NUM>. In some embodiment engineering a pin to fail first protects the smooth stem <NUM> because the smooth stem <NUM> can only be replaced by taking the valve apart.

Some embodiments properly size the valve mechanisms with sufficient Safety Factors applied such that the valve mechanism is stronger from inside the valve <NUM> outward to the actuator <NUM>. In some embodiments the threaded stem <NUM> and drive nut <NUM> are wear components and can be replaced in the field without taking the valve off-line. In some embodiments this is accomplished by removing the actuator <NUM> from the actuator housing <NUM> and removing the threaded stem <NUM>.

In some embodiments acme threads used on the second stem <NUM> are sized to minimize wear and withstand combined tensile, torsional and bearing stresses at maximum actuator output. In some embodiments acme working thread connection is sized to exceed the actuator <NUM> maximum output. In some embodiments the acme threads are designed with low bearing stress between the threaded stem and the drive nut <NUM> to improve longevity and minimize wear.

In some embodiments the first securing pin <NUM> is engineered to fail before any other part of the coupler <NUM> assembly. In some embodiments the second securing pin <NUM> is engineered to fail before any other part of the coupler <NUM> assembly.

In some embodiments the coupler comprises an adjustment gap <NUM> between the proximal end of the first stem <NUM> and the proximal end of the second stem <NUM>. In some embodiments the adjustment gap allows the selective placement of the gate <NUM> stroke position which can be adjusted by rotating the v-threads on the proximal end of the firs stem or the proximal end of the second stem <NUM> for a precise stroke. In some embodiments the coupler is configured to allow the user to selectively set the depth of engagement between the stem and the coupler <NUM> so as to be adjusted by rotating the stem in the screw threads to adjust the position of the stem in the coupler <NUM>. In some embodiments the coupler <NUM> comprises a gate coupled to the first stem <NUM> wherein the gate closed position is set or adjusted by the depth of engagement of the first stem <NUM> in the first stem <NUM> receiving channel so as to avoid an overtorque condition. Thus in some embodiments the gate is overtorqued by placing the gate <NUM> beyond an optimum closed position the securing pin fails to prevent damage to the smooth stem <NUM> or the coupling assembly <NUM>.

Claim 1:
A valve stem coupling assembly (<NUM>) for isolating a torque load from a thrust load comprising:
a first stem (<NUM>);
a second stem (<NUM>);
a coupler (<NUM>) comprising
a first stem receiving channel (<NUM>),
a second stem receiving channel (<NUM>) aligned with the first stem receiving channel (<NUM>),
a plurality of pin receiving channels (<NUM>) oriented nonparallel the first and second stem receiving channels (<NUM>, <NUM>) wherein the first stem (<NUM>) is selectively coupled to the first stem receiving channel (<NUM>), the second stem (<NUM>) is selectively coupled to the second stem receiving channel (<NUM>), a first securing pin (<NUM>) selectively inserted in a first pin receiving channel of the plurality of pin receiving channels (<NUM>) so as to secure the orientation of the first stem (<NUM>) in the first stem receiving channel (<NUM>) and a second securing pin (<NUM>) selectively inserted in a second pin receiving channel of the plurality of pin receiving channels (<NUM>) so as to secure the orientation of the second stem (<NUM>) in the second stem receiving channel (<NUM>) wherein the first and second stem (<NUM>, <NUM>), first and second securing pin (<NUM>, <NUM>) and coupler (<NUM>) comprise the coupling assembly (<NUM>);
wherein the coupler (<NUM>) is configured to couple the first stem (<NUM>) and the second stem (<NUM>) so as to isolate a torque load and a thrust load; and characterised in that:
a coupler end of the first stem (<NUM>) comprises a forked receiving portion (<NUM>) configured to receive the first securing pin (<NUM>) at a variety of positions along in the forked receiving portion (<NUM>).