Regulator Having Check Valve Manifold for Use in Subsea Control Circuit

Abstract

A regulator valve has a check valve manifold for use in subsea control circuits. For example, the regulator valve having the check valve manifold can be used in a circuit between a directional control valve and an actuator for a gate valve. The check valve manifold can have a flange that attaches to the regulator valve to communicate with the supply-side and outlet-side of the regulator valve. Internal communication inside the manifold includes a check valve. If the pressure in the circuit downstream of the regulator valve needs to be vented, the check valve can open to allow the pressure to bleed from the outlet-side back to the supply-side without needing to pass through the internal pressure control valve of the regulator.

Description

BACKGROUND OF THE DISCLOSURE

FIG. 1 illustrates a schematic of a prior art control circuit 10 for an actuator 40 of a gate valve 50 used in a subsea control module. The control circuit 10 includes a regulator 20 and a directional control valve (DCV) 30. The regulator 20 connects to a supply 12 of hydraulic fluid and regulates the pressure of the hydraulic fluid for supply to the actuator 40. The directional control valve 30 is downstream of the regulator 20 and includes an inlet (I) connected to the regulator's output (O). A vent (V) of the directional control valve 30 connects to the environment 16 (e.g., seawater). A pilot port (P) of the directional control valve 30 connects to a pilot supply 14.

The regulator 20 reduces the supply pressure of the hydraulic fluid going into the directional control valve 30 to a value suitable for the gate valve actuator 40. When the directional control valve 30 receives a pilot signal at the pilot port (P), the directional control valve 30 opens and sends pressurized hydraulic fluid from the inlet (1) to the output (O) for passage to the gate valve actuator 40 to open the gate valve 50 communicating between flow connections 52, 54. When the pilot pressure is removed from the directional control valve 30, the directional control valve 30 closes to its default state, which is shown in FIG. 1. For the gate valve 50 to close, the hydraulic pressure above the piston in the actuator 40 must be expelled. The directional control valve 30 has a vent circuit that connects the output (O) to the vent (V) so the hydraulic fluid can exhaust to the environment 16 and the gate valve 50 can close.

Although this arrangement of the control circuit 10 is effective, there may be implementations where this arrangement cannot be used or where different functionality is needed. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

SUMMARY OF THE DISCLOSURE

A control circuit disclosed here is used for an actuator of a gate valve used in a subsea control module in a subsea environment. The control circuit comprises a directional control valve and a regulator. The directional control valve has: an input in communication with a hydraulic fluid supply, a vent in communication with the subsea environment, a pilot in communication with a pilot supply, and an output. The directional control valve is configured in closed and opened states in response to the pilot supply at the pilot. The directional control valve in the opened state communicates the hydraulic fluid supply at the input with the output. Meanwhile, the directional control valve in the closed state communicates the output with the vent.

The regulator has a supply and an outlet and has a seal arrangement between the supply and the outlet. The supply is in communication with the output of the directional control valve, and the outlet is in communication with the actuator. The seal arrangement is configured to reduce hydraulic pressure of the hydraulic fluid supply communicated from the supply to the outlet, and the seal arrangement is configured to prevent communication of the hydraulic pressure on the outlet to the supply. The regulator has a check valve connecting the supply with the outlet. The check valve is configured to permit at least a portion of the hydraulic pressure at the outlet to bypass the seal arrangement from the outlet to the supply of the regulator to the directional control valve.

An apparatus disclosed herein is used for a subsea control module used in a subsea environment. The apparatus comprises a gate valve, an actuator, a direction control valve, and a regulator. The gate valve has flow connections and has a gate movable between the flow connections. The actuator is connected to the gate valve and is configured to move the gate in response to hydraulic pressure. The directional control valve and the regulator are configured as described above in the control circuit.

A regulator is disclosed herein to regulate hydraulic pressure for an actuator of a gate valve of a subsea control module in a subsea environment. The regulator comprises a housing, a container, a seal arrangement, and a check valve. The housing has a supply and an outlet, and the housing defines an interior communicating with the supply and the outlet. The container is movably disposed in the interior like a piston in response to the hydraulic pressure in the interior.

The seal arrangement is disposed on the container and is movable with the container relative to the supply and the outlet. The seal arrangement is configured to reduce the hydraulic pressure of the hydraulic fluid supply communicated from the supply to the outlet. Additionally, the seal arrangement is configured to prevent communication of the hydraulic pressure on the outlet to the supply. The check valve is disposed in communication between the supply and the outlet. The check valve is configured to permit at least a portion of the hydraulic pressure at the outlet to bypass the seal arrangement from the outlet to the supply.

The housing can comprise a flow plate having a flow port exposed in the interior and communicating with the supply. The seal arrangement can be biased against the flow plate and can be movable with the container relative to the flow port.

The housing can have a vent side and can comprise a vent plate having a vent port exposed in the interior and communicating with the vent side. The seal arrangement can be biased against the vent plate and can be movable with the container relative to the vent port and the flow port.

The seal arrangement can comprise opposing supply seals disposed in the container and biased away from one another respectively toward the vent plate and the flow plate. Each of the opposing supply seals has a flow passage and a seal face. The seal face is configured to seal with a respective one of the vent plate and flow plate, and the flow passage is configured to produce a pressure change in the hydraulic fluid.

The seal arrangement can comprise opposing vent seals disposed in the container and biased away from one another toward the vent plate and the flow plate. Each of the opposing vent seals has a flow passage and a seal face. The seal face is configured to seal with a respective one of the vent plate and flow plate, and the flow passage is configured to produce a pressure change in the hydraulic fluid.

A manifold can be affixable to the housing. The manifold has a supply port, an outlet port, and the check valve. The supply port can be connected by a supply line to the supply, and the outlet port can be connected by an outline line to the outlet. The outlet line and the supply line are interconnected by the check valve. The check valve is configured to open in response to outlet-side pressure from the outlet line exceeding a level of supply-side pressure from the supply line and is configured to allow the hydraulic fluid pressure from the outlet port to flow back to the supply port, bypassing the interior.

A spring can be disposed in the housing and can bias the container against the hydraulic pressure in the interior.

A method disclosed herein is used for a subsea control module in a subsea environment. The method comprises activating an actuator for a gate valve by: opening a directional control valve communicating a hydraulic fluid supply at an input with an output, and reducing hydraulic pressure of the hydraulic fluid supply from the output to the actuator using a regulator having a supply in communication with the output and having an outlet in communication with the actuator.

The method comprises deactivating the actuator for the gate valve by: closing the directional control valve communicating the output with a vent, preventing communication of the hydraulic pressure on the outlet to the supply of the regulator using a seal arrangement in the regulator, permitting at least a portion of the hydraulic pressure from the actuator to bypass the seal arrangement to the directional control valve through a check valve connecting the outlet to the supply of the regulator, and expelling the hydraulic pressure bypassing the regulator from the vent of the directional control valve to the subsea environment.

The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic of a prior art control circuit for an actuator of a gate valve used in a subsea control module.

FIG. 2 illustrates a schematic of a control circuit according to the present disclosure for an actuator of a gate valve used in a subsea control module.

FIG. 3A illustrates a cross-sectional view of a regulator valve of the present disclosure.

FIG. 3B illustrates a side elevational view of the regulator valve.

FIG. 3C illustrates a back elevational view of the regulator valve.

FIG. 3D illustrates a plan view of the top of the regulator valve.

FIG. 3E illustrates an end section of the regulator valve.

FIG. 4 illustrates a detailed cross-section of a pressure control valve arrangement in the regulator valve.

FIG. 5 illustrates a cross-sectional view of a control manifold for the regulator valve.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 2 illustrates a schematic of a control circuit 100 of the present disclosure for an actuator 40 of a gate valve 50. As will be appreciated, the control circuit 100 can be used in a Subsea Control Module (SCM) for several functions.

The control circuit 100 includes a regulator 110 and a directional control valve (DCV) 108. In this control circuit 100 and in contrast to the conventional circuit of FIG. 1, the regulator 110 is downstream of the directional control valve 108. This circuit 100 can be used in implementations having mixed operating pressures and can be used in legacy systems where all available lines are utilized, and no more new lines can be added. There may be additional reasons for the arrangement in this control circuit 100.

The directional control valve 108 has an input (I) that connects to a supply 102 of hydraulic control fluid. A vent (V) of the directional control valve 108 connects to the environment 106 (e.g., seawater), and a pilot port (P) of the directional control valve 108 connects to a pilot supply 104. An output (O) of the direction control valve 108 connects to the regulator 110. For its part, the regulator 110 has a supply side (S) connected to the directional control valve 108 and has an outlet side (O) connected to the actuator 40 for the gate valve 50.

The directional control valve 108 can be configured in closed and opened states in response to the pilot supply at the pilot port (P). When the directional control valve 108 receives a pilot signal at the pilot port (P), for example, the directional control valve 108 opens and sends hydraulic control fluid from the input (I) to the output (O). The hydraulic control fluid passes to the regulator 110, which reduces the pressures to a value suitable for the gate valve actuator 40. From there, the hydraulic control fluid goes to the actuator 40, closing the gate valve 50. For example, the gate valve 50 can include a gate being movable by the actuator 40 between an inlet flow connection 52 and an outlet flow connection 54. The flow controlled by the gate valve 50 can be used for any suitable purposes in the subsea control module.

When the pilot signal is removed from the directional control valve 108, the directional control valve 108 closes to a closed state as shown in FIG. 2. Pressure in the line between the regulator 110 and the directional control valve 108 goes out through the vent circuit to the environment 16 by passing from the output (O) to the vent (V). An internal shear seal arrangement of the regulator 110, however, seals off pressure on the outlet side (O) of the regulator 110, preventing that pressure from flowing out the vent circuit in the directional control valve 108. This locks the hydraulic pressure in the gate valve actuator 40 preventing it from closing.

For the gate valve 50 to close, the hydraulic pressure above the piston in the actuator 40 must be expelled. To do this, a manifold 160 having a check valve 170 disposed on the regulator 110 permits the hydraulic fluid to pass from the outlet side (O) to the supply side (S), bypassing the internal seal arrangement of the regulator 110 to the directional control valve 108, where the fluid can then be exhausted through the vent circuit to the environment 106.

FIG. 3A illustrates a cross-sectional view of a regulator valve 110 of the present disclosure; FIG. 3B illustrates a side elevational view of the regulator valve 110; FIG. 3C illustrates a back elevational view of the regulator valve 110; FIG. 3D illustrates a plan view of a top of the regulator valve 110; and FIG. 3E illustrate an end-section of the regulator 110.

The regulator valve 110 includes a housing 112, which is made up of a spring chamber 120, a valve chamber 130, a vent manifold or flange 140, and a control manifold or flange 160. The spring chamber 120 attaches to the valve chamber 130, and the manifolds 140, 160 affix to sides of the valve chamber 130.

The spring chamber 120 holds a spring 124 in the chamber's interior 122 between opposing support plates 125a-b. The upper support plate 125a is engaged by a bearing and an adjustment screw 127. The lower support plate 125b is engaged by a bearing to a seal container or piston 128. The seal container 128 is disposed in an interior or bore 132 of the valve chamber 130. The container 128 holds a configuration of pressure control valves 150, which are shown in detail in FIG. 4. The container 128 is movably disposed in the interior 132 in response to hydraulic pressure in the interior 132 acting against the bias of the spring 124.

The vent manifold 140 mounted to the valve chamber 130 has a vent port 142 that communicates with a vent plate 145 in the valve chamber 130. The interior 132 of the valve chamber 130 communicates through the vent plate 145 with the vent port 142. The vent manifold 140 can be used for venting purposes as needed in a control circuit, such as the circuit 100 in FIG. 2.

The control manifold 160 mounted to the valve chamber 130 has a supply port or inlet 164a and a regulated port or outlet 164b. As best shown in FIG. 3A, the inlet 164a communicates via a supply passage 166a with a flow plate 135 in the valve chamber 130, and the interior 132 of the valve chamber 130 communicates via an outlet passage 166b to the outlet 164b. As generally shown in FIG. 3B, the supply and outlet passages 166a-b interconnect with one another via internal lines inside the manifold 160. A check valve 170 described in more detail below prevents fluid communication from the supply passage 166a to the outlet passage 166b and permits at least some fluid communication from the outlet passage 166b to the supply passage 166a.

Additional detail of the control manifold 160 is illustrated in the cross-sectional view of FIG. 5. The control manifold 160 includes a manifold body 162 that can bolt to the valve chamber 130. The supply port 164a communicates with an internal supply line 165a that connects to the supply passage 166a in the manifold body 162. The supply port 164a connected to the supply line 165a also connects to a supply side of the check valve 170 installed in the manifold body 162.

As seen in FIG. 3A, the supply passage 166a communicates with the flow plate 135 of the valve chamber 130. Supply of hydraulic fluid from the directional control valve (108) can enter the valve chamber's interior 132 through the supply passage 166a and the flow plate 135 to act upon the seal container 128 and the pressure control valve arrangement 150.

As seen in FIG. 5, the outlet port 164b communicates with an outlet line 165b that connects to the outlet passage 166b. As seen in FIG. 3A, this outlet passage 166b communicates with the interior 132 of the valve chamber 130. Regulated hydraulic fluid from the valve chamber's interior 132 can pass through the outlet passage 166b to the outlet port 164b of the manifold 160.

Additionally as shown in FIG. 5, the outlet line 165b connects the outlet port 164b to an outlet side of the check valve 170. Inside the manifold 160, the check valve 170 has supply-side pressure (from line 165a) and outlet-side pressure (from line 165b) acting on it. When the outlet-side pressure from the outlet line 165b exceeds the supply-side pressure from the supply line 165a (including any internal bias of the check valve 170), the check valve 170 opens and allows the hydraulic fluid from the outlet port 164b to flow back to the supply port 164a, bypassing the interior 132 of the valve chamber 130 of the regulator valve 110 and relieving the hydraulic pressure downstream from the regulator 110.

For manufacturing and machining purposes, side access points of the communication lines 165a-b have sealed plugs 167b. The side access 164c for insertion of the check valve 170 also includes a sealed plug 167c.

As noted above with respect to the control circuit 100 in FIG. 2, when the pilot signal is removed from the directional control valve 108, the directional control valve 108 closes. Pressure between the regulator 110 and the directional control valve 108 goes out through the vent circuit to the environment 16. The internal seal arrangement of the regulator 110, however, seals off pressure on the outlet side (O) of the regulator 110, preventing that pressure from flowing back through the regulator 110 to the supply side (S). Here, however, the check valve 170 permits the hydraulic fluid to flow around the internal seals of the regulator 110 and to flow back to the directional control valve 108. In this way, the hydraulic fluid can then bleed out the vent circuit in the directional control valve 108 and can be exhausted through the vent circuit to the environment 106.

FIG. 4 illustrates a detailed cross-section of the internal seal arrangement 150 for the pressure control used inside the regulator valve's chamber 130. An outlet seal cage 152a is disposed in a first pocket 129a of the seal container 128 and is sealed therein with an annular O-ring seal. The outlet seal cage 152a holds opposing vent seals 154a therein. Annular O-ring seals are used to seal the vent seals 154a in the outlet seal cage 152a. The vent seals 154a define a flow passage therethrough and have a circumferential seal face disposed thereabout on the outer end. The opposing vent seals 154a can move laterally in response to hydraulic pressure and are biased away from one another by a central spring 156a. When biased outward, the faces of the vent seals 154a respectively engage internal surfaces 147, 137 of the flow plates 145, 135, which are exposed on opposing sides of the interior 132 to form shear seals. The flow passages in the vent seals 154a have a change in diameter to produce a pressure change (e.g., pressure drop) in the hydraulic fluid allowed to pass through the vent seals 154a.

In a similar manner, an inlet seal cage 152b is disposed in a second pocket 129b of the seal container 128 and is sealed therein with an annular O-ring seal. The inlet seal cage 152b holds opposing supply seals 154b therein. Annular O-ring seals and backup seals are used to seal the supply seals 154b in the inlet seal cage 152b. The supply seals 154b define a flow passage therethrough and have a circumferential seal face disposed thereabout on the outer end. The opposing supply seals 154b can move laterally in response to hydraulic pressure and are biased away from one another by a central spring 156b. When biased outward, the faces of the supply seals 154b respectively engage the surfaces 147, 137 of the flow plates 145, 135 on opposing sides of the interior 132 to form shear seals. The flow passages in the supply seals 154b have a change in diameter to produce a pressure change (e.g., pressure drop) in the hydraulic fluid allowed to pass through the supply seals 154b.

The seals 154a-b of the seal arrangement 150 control the flow and the pressure of the hydraulic fluid communicated from the supply side S (e.g., 166a, 164a) to the outlet side O (e.g., 166b, 164b) communicating with the interior 132 of the regulator 110. As can be seen, the vent seals 154a throttle cross-flow between them, but the faces of the vent seals 154a slidably seal on the flat surfaces 147, 137 of the flow plates 145, 135. The vent seals 154a can unseal from the faces 147, 137 against the bias of the central spring 156a in response to hydraulic pressure, and the vent seals 154a can slide along the faces 147, 137 with movement of the container 128 against the bias of the valve's spring (124). One vent seal 154a seals adjacent the vent passage 142, while the other vent seal 154a seals adjacent the supply passage 166a.

The supply seals 154b throttle cross-flow between them, but the faces of the supply seals 154b slidably seal on the flat surfaces 147, 137 of the flow plates 145, 135. The supply seals 154b can unseal from the faces 147, 137 against the bias of the central spring 156b in response to hydraulic pressure, and the supply seals 154b can slide along the faces 147, 137 with movement of the container 128 against the bias of the valve's spring (124). One supply seal 154b seals adjacent the interior 132 that communicates with the outlet passage 166b, while the other supply seal 154a seals adjacent the supply passage 166a and outlet passage 166b.

The regulator valve 110 of the present disclosure may be used with or without the control manifold 160 having the check valve 170. Without the control manifold 160 and using an appropriate flow manifold for the supply and outlet, the regulator valve 110 can be used in a conventional circuit 10 such as discussed above with respect to FIG. 1. With the control manifold 160 having the check valve 170, however, the regulator valve 110 can be used in the alternative control circuit 100, such as discussed above with respect to FIG. 2. However, the regulator valve 110 having the control manifold 160 with the check valve 170 may also be used in the conventional control circuit 10 to provide additional functionality.

The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.

Claims

1. A regulator to regulate hydraulic pressure of hydraulic fluid communicated from a hydraulic fluid source to an actuator of a gate valve in a subsea environment, the regulator comprising: a supply-side in communication with the hydraulic fluid source;an outlet-side in communication with the actuator;a seal arrangement disposed between the supply-side and the outlet-side, the seal arrangement being configured to reduce the hydraulic pressure of the hydraulic fluid communicated from the supply-side to the outlet-side, the seal arrangement configured to prevent communication of the hydraulic pressure at the outlet-side to the supply-side; anda bypass being configured to prevent the hydraulic pressure at the supply-side from bypassing the seal arrangement and communicating with the actuator, the bypass being configured to permit at least a portion of the hydraulic pressure at the outlet-side to bypass the seal arrangement and to communicate with the hydraulic fluid source.

2. The regulator of claim 1, comprising: a housing having the supply-side and the outlet-side, the housing defining an interior communicating with the supply-side and the outlet-side; anda container movably disposed in the interior in response to the hydraulic pressure in the interior,wherein the seal arrangement is disposed on the container and is movable with the container relative to the supply-side and the outlet-side.

3. The regulator of claim 2, comprising a spring disposed in the housing and biasing the container against the hydraulic pressure in the interior.

4. The regulator of claim 2, wherein: the housing comprises first and second opposing plates, the first opposing plate having a flow port exposed in the interior and communicating with the supply-side; andthe seal arrangement comprises opposing seals disposed in the container and being biased away from one another respectively toward the first and second opposing plates, each of the opposing seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the first and second opposing plates, the flow passage being configured to produce a pressure change in the hydraulic fluid.

5. The regulator of claim 2, wherein: the housing comprises a flow plate having a flow port exposed in the interior and communicating with the supply-side; andthe seal arrangement is biased against the flow plate and is movable with the container relative to the flow port.

6. The regulator of claim 5, wherein the housing has a vent side;the housing comprises a vent plate having a vent port, the vent port exposed in the interior and communicating with the vent side; andthe seal arrangement is biased against the vent plate and is movable with the container relative to the vent port and the flow port.

7. The regulator of claim 6, wherein the seal arrangement comprises opposing supply seals disposed in the container and being biased away from one another respectively toward the vent plate and the flow plate, each of the opposing supply seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the vent plate and the flow plate, the flow passage being configured to produce a pressure change in the hydraulic fluid.

8. The regulator of claim 6, wherein the seal arrangement comprises opposing vent seals disposed in the container and biased away from one another toward the vent plate and the flow plate, each of the opposing vent seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the vent plate and the flow plate, the flow passage being configured to produce a pressure change in the hydraulic fluid.

9. The regulator of claim 1, wherein the bypass comprises a supply line, an outlet line, and a check valve, the supply line connected to the supply-side, the outlet line connected to the outlet-side, the check valve interconnecting the outlet line and the supply line, the check valve being configured to open in response to outlet-side pressure of the outlet line exceeding a level of supply-side pressure of the supply line and being configured to allow the hydraulic pressure from the outlet-side to flow back to the hydraulic fluid source, bypassing the seal arrangement of the regulator.

10. An apparatus for a subsea control module used in a subsea environment, the apparatus comprising: a gate valve having a movable gate;an actuator connected to the gate valve and being configured to move the movable gate in response to hydraulic pressure of a hydraulic fluid;a directional control valve having an input, an output, and a vent, the input in communication with a hydraulic fluid source, the vent in communication with the subsea environment, the directional control valve being operable in first and second states, the directional control valve in the first state communicating the hydraulic fluid from the input to the output, the directional control valve in the second state communicating the output with the vent; anda regulator comprising: a supply-side in communication with the output of the directional control valve;an outlet-side in communication with the actuator;a seal arrangement disposed between the supply-side and the outlet-side, the seal arrangement being configured to reduce the hydraulic pressure of the hydraulic fluid communicated from the supply-side to the outlet-side, the seal arrangement configured to prevent communication of the hydraulic pressure at the outlet-side to the supply-side; anda bypass being configured to prevent the hydraulic pressure at the supply-side from bypassing the seal arrangement and communicating with the actuator, the bypass being configured to permit at least a portion of the hydraulic pressure at the outlet-side to bypass the seal arrangement and to communicate with the output of the directional control valve.

11. The apparatus of claim 10, wherein: the regulator comprises: a housing having the supply-side and the outlet-side, the housing defining an interior communicating with the supply-side and the outlet-side; anda container movably disposed in the interior in response to the hydraulic pressure in the interior; andthe seal arrangement is disposed on the container and is movable with the container relative to the supply-side and the outlet-side.

12. The apparatus of claim 11, wherein: the housing comprises first and second opposing plates, the first opposing plate having a flow port exposed in the interior and communicating with the supply-side; andthe seal arrangement comprises opposing seals disposed in the container and being biased away from one another respectively toward the first and second opposing plates, each of the opposing seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the first and second opposing plates, the flow passage being configured to produce a pressure change in the hydraulic fluid.

13. The apparatus of claim 10, wherein to activate the actuator, the directional control valve is operable in the first state, the regulator is configured to reduce the hydraulic pressure of the hydraulic fluid from the directional control valve to the actuator, and the bypass is configured to prevent the hydraulic pressure at the supply-side from bypassing the seal arrangement and communicating with the actuator; andwherein to deactivate the actuator, the directional control valve is operable in the second state, the seal arrangement of the regulator is configured to prevent communication of the hydraulic pressure at the outlet-side to the supply-side of the regulator, and the bypass is configured to permit at least the portion of the hydraulic pressure at the outlet-side to bypass the seal arrangement and to communicate with the directional control valve.

14. A method used for a subsea control module in a subsea environment, the method comprising: activating an actuator for a gate valve by: operating a directional control valve in a first state,reducing hydraulic pressure of a hydraulic fluid supplied from the directional control valve to the actuator using a seal arrangement in a regulator, the seal arrangement disposed between a supply-side and an outlet-side of the regulator, the supply-side in communication with the directional control valve, the outlet-side in communication with the actuator, andpreventing the hydraulic pressure from the directional control valve from bypassing the seal arrangement in the regulator through a bypass to the actuator; anddeactivating the actuator for the gate valve by: operating the directional control valve in a second state,preventing the hydraulic pressure at the outlet-side of the regulator from communicating through the seal arrangement in the regulator to the supply-side of the regulator, andpermitting at least a portion of the hydraulic pressure from the actuator to bypass the seal arrangement through the bypass and to communicate with the directional control valve.

15. The method of claim 14, wherein operating the directional control valve in the second state comprises communicating an output of the directional control valve with a vent of the directional control valve; and wherein the method further comprises expelling the hydraulic pressure bypassing the seal arrangement in the regulator from the vent of the directional control valve to the subsea environment.

16. The method of claim 14, wherein operating the directional control valve comprises: communicating a pilot source with a pilot on the directional control valve; andchanging the directional control valve between the first and second states in response to the pilot source at the pilot.

17. The method of claim 14, wherein reducing the hydraulic pressure of the hydraulic fluid using the seal arrangement comprises: communicating the hydraulic fluid with a first port defined in a first plate disposed in an interior of the regulator;biasing the seal arrangement in the interior relative to the first plate; andmoving the seal arrangement in the interior relative to the first port by moving a container in the interior, the container having the seal arrangement disposed thereon.

18. The method of claim 17, further biasing the container against the hydraulic pressure in the interior using a spring disposed in the regulator.

19. The method of claim 17, further comprising: communicating the interior with a second port defined in a second plate on disposed in the interior of the regulator;biasing the seal arrangement in the interior relative to the second plate; andmoving the seal arrangement in the interior relative to the second port by moving the container in the interior.

20. The method of claim 19, wherein biasing the seal arrangement relative to the first and second plates comprises biasing opposing first seals disposed in the container and being biased away from one another respectively toward the first and second plates, each of the opposing first seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the first and second plates, the flow passage being configured to produce a pressure change in the hydraulic fluid.

21. The method of claim 19, wherein biasing the seal arrangement relative to the first and second plates comprises biasing opposing second seals disposed in the container and being biased away from one another toward the first and second plates, each of the opposing second seals having a flow passage and a seal face, the seal face being configured to seal with a respective one of the first and second plates, the flow passage being configured to produce a pressure change in the hydraulic fluid.

22. The method of claim 14, wherein permitting at least the portion of the hydraulic pressure from the actuator to bypass the seal arrangement through the bypass and to communicate with the directional control valve comprises: opening a check valve of the bypass in response to a first pressure level at the outlet-side exceeding a second pressure level at the supply-side; andallowing the hydraulic pressure from the outlet-side to flow back to the supply-side, bypassing the seal arrangement in the regulator.