Self-regulating surplussing check valve

Abstract

A check valve assembly (100, 200) is provided for subsea applications. The check valve assembly comprises a housing (102, 202), having an inlet port (106, 206) and an outlet port (108, 208) forming an internal fluid passageway through the housing; a valve member (112, 212), moveable within the internal fluid passageway between a first position, where fluid flow through the internal fluid passageway is prevented, and a second position, where fluid flow through the internal fluid passageway is permitted; a biasing member (110, 210), adapted to urge the valve member into the first position at a predetermined cracking force, and a pressure interface (116, 216). The pressure interface operatively links the valve member and an external fluid of a region exterior of the check valve assembly so as to provide a supplemental force, proportional to the ambient pressure of the external fluid, adapted to urge the valve member towards the first position.

Claims

1. A subsea check valve assembly for subsea applications, comprising: a housing, having an inlet port and an outlet port forming an internal fluid passageway through said housing between the inlet port and the outlet port; a valve member comprising a first upstream surface in fluid communication with the inlet port and a second downstream surface, the valve member being moveable within said internal fluid passageway between a first position, where fluid flow through said internal fluid passageway is prevented, and a second position, where fluid flow through said internal fluid passageway is permitted; a biasing member, in contact with at least part of said second downstream surface and adapted to urge said valve member into said first position at a predetermined cracking force, and a pressure interface to provide a supplemental force to urge said valve member towards said first position, wherein the pressure interface comprises at least one external fluid passageway adapted to provide direct fluid communication between an external fluid located in a region exterior of the subsea check valve and at least part of said second downstream surface, wherein the supplemental force is proportional to the ambient pressure of said external fluid located in the region exterior of the subsea check valve.

2. A subsea check valve assembly according to claim 1, further comprising a valve seat surface formed within said internal fluid passageway coaxially about said inlet port.

3. A subsea check valve assembly according to claim 2, wherein said first upstream surface of said valve member is adapted to sealingly engage said valve seat surface when in said first position.

4. A subsea check valve assembly according to claim 3, wherein said second downstream surface is located at an opposing side to said first upstream surface.

5. A subsea check valve assembly according to claim 1, wherein said at least one external fluid passageway is fluidly sealed from said internal fluid passageway.

6. A subsea check valve assembly according to claim 1, wherein said valve member further comprises a seal portion and at least one flow portion at an upstream side of said valve member, the seal portion being engageable with said housing to prevent fluid flow past said seal portion, and wherein said flow portion is adapted to provide a fluid path between said inlet port and said outlet port through said internal fluid passageway.

7. A subsea check valve assembly according to claim 6, wherein said seal portion sealingly closes said fluid path of said flow portion when said valve member is in said first position, and wherein said flow portion provides fluid flow through said fluid path when said valve member is in said second position.

8. A subsea check valve assembly according to claim 1, wherein said biasing member is a spring.

9. A subsea check valve assembly according to claim 1, further comprising a snap-action mechanism adapted to independently move said valve member into said first position and/or said second position at a predetermined condition.

10. A subsea check valve assembly according to claim 9, wherein said predetermined condition is a predetermined distance between the valve member and said first position and/or said second position.

11. A subsea check valve assembly according to claim 9, wherein said snap-action mechanism comprises at least one magnetic element adapted to provide a force acting on said valve member so as to urge said valve member towards said first position and/or said second position.

12. A stab connector for providing a fluid flow path between a first fluid reservoir and a second fluid reservoir, comprising: a stab body coupleable to a receptacle in fluid communication with the second fluid reservoir, and a subsea check valve assembly according to claim 1, operatively arranged within said stab body and adapted to control fluid flow between the first fluid reservoir and the second fluid reservoir.

13. A stab connector according to claim 12, wherein the pressure interface of said subsea check valve assembly is arranged within the distal end portion of said stab body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred embodiment of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an example of a typical offshore setup when servicing a pipeline, either for installation, repair or pigging utilizing a flexible hose that is extended from a surface vessel;

(3) FIG. 2 shows (a) a cross section of a known Surplussing Valve (Moffat 2000 Ltd) as currently used to prevent subsea hose collapse, and (b) a typical embodiment of the Surplussing Valve, as well as, (c) the embodiment complete with Female FIG. 1502 Hammer-Lug Union on the inlet and a Male FIG. 1502+Nut on the outlet;

(4) FIG. 3 shows a cross section of a preferred embodiment of the check valve assembly of the present invention;

(5) FIG. 4 shows a functional diagram of the check valve assembly of FIG. 3 when (a) in its closed state, and (b) in its open state;

(6) FIG. 5 shows a cross section of an alternative embodiment of the check valve assembly of the present invention;

(7) FIG. 6 shows a functional diagram of the check valve assembly of FIG. 5 when (a) in its closed state, and (b) in its open state;

(8) FIG. 7 shows a cross section of an exemplary stab connector incorporating the check valve assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) In accordance with the preferred first embodiment of the present invention, FIG. 3 depicts a check valve assembly 100 having a housing 102, an inlet port 106, an outlet port 108, a biasing member 110 in form of a compression spring, a valve member 112 and corresponding valve seat surface 114, as well as a pressure interface 116 linking the pressure provided by the external fluid with a contact surface of the valve member 112. Sealing members 118 are arranged in the housing 102 and valve member 112 so as to fluidly seal the fluid flow path between inlet port 106 and outlet port 108 when the valve member 112 is in its closed position, and to fluidly seal the fluid flow path between the inlet port 106 and the outlet port 108 from the pressure interface linking the valve member 112 with the pressure provided by the external fluid, independent of the position of the valve member 112.

(10) FIG. 4 (a) shows the check valve assembly 100 in situ (connecting hose and pipeline not shown) with the hose fluid 120 pressing against an upstream surface of the valve member 112 with an internal hose pressure P.sub.1 provided by a pump (not shown) that is connected to the hose (not shown). A constant biasing force, such as a spring force F.sub.s provided by the compression spring 110, urges the valve member 112 towards the valve seat surface 114, so as to seal the fluid flow path between the inlet port 106 and the outlet port 108. In this particular example, the compression spring 110 is operatively arranged between a downstream surface 122 of the valve member 112 and an interior wall 124 of the housing 102. The pressure interface 116, linking the external fluid (not shown) with the valve member 112, is in form of an open external fluid path between the external fluid (not shown) and the downstream surface 122 of the valve member 112. In accordance with Pascal's law, the hydrostatic pressure P.sub.h-x at the subsea depth X is applied directly to the downstream surface 122 of the valve member, so as to supplement the constant spring force F.sub.s provided by the compression spring 110. Therefore, the cracking pressure P.sub.c(x) the hose fluid 120 has to overcome at the subsea depth X to open the fluid flow path of the check valve assembly 100 is determined by the force F.sub.h(x) provided by the hydrostatic pressure P.sub.h-x at subsea depth X acting on the downstream surface 122 of the valve member 112, the spring force F.sub.s (constant) provided by the compression spring 110 and the internal pressure of the pipeline P.sub.1 (assumed constant) acting on the downstream surface 122.
P.sub.c(x)=F.sub.h(x)+F.sub.s+P.sub.1[1]

(11) In order to prevent hose collapse, the hose is pressurized at an internal hose pressure P.sub.1 that is directly proportional to the hydrostatic pressure P.sub.h-x. Hence, the cracking pressure Pc(x) is proportional to the internal hose pressure P.sub.1 at subsea depth X, therefore, automatically providing the appropriate cracking pressure P.sub.c suitable for the internal hose pressure P.sub.1 at subsea depth X. Any significant pressure drop in the hose (not shown) that reduces P.sub.1 to below P.sub.c(x), causes the valve member 112 to move back into its closed position, therefore preventing the hose to collapse.

(12) In accordance with an alternative second embodiment, FIG. 5 depicts a check valve assembly 200 comprising a housing 202, an inlet port 206, an outlet port 208, a biasing member 210 in form of a compression spring, a valve member 212, a valve seat surface 214, a pressure interface 216, sealing members 218 and a downstream surface 222. In this particular embodiment, the inlet port 206 and outlet port 208 of the check valve assembly 200 are arranged perpendicular to each other. The pressure interface 216 is arranged in line with the inlet port 206 so that the valve member 212 can move between a closed position, where the fluid flow between inlet port 206 and outlet port 208 is prevented, and an open position, where fluid flow between inlet port 206 and outlet port 208 is permitted. FIG. 6 shows the alternative check valve assembly 200 in situ (without hose and pipeline attachments) (a) in its closed position, where the internal hose pressure P.sub.1 is less than the cracking pressure Pc(x) provided at subsea depth X, and (b) in its open position, where the internal hose pressure P.sub.1 exceeds the cracking pressure P.sub.c(x) at subsea depth X.

(13) During operation, the internal hose fluid 220 provides a pressure P.sub.1 against the valve member 212. As soon as P.sub.1 exceeds a cracking pressure P.sub.c(x), which is determined by a force F.sub.h(X) provided by the hydrostatic pressure P.sub.h-x at subsea depth X acting on the downstream surface 222 of the valve member 212 and the spring force F.sub.s provided by the compression spring 210, the valve member 212 is moved into its open position so as to provide a fluid flow path between the inlet port 206 and the outlet port 208. The cracking pressure P.sub.c(x) does not include the internal pipeline pressure P.sub.1, because the outlet port 208 is perpendicular to the inlet port 206 and pressure interface 216. Any significant pressure drop in the hose reducing P.sub.1 to below P.sub.c(x), causes the valve member 212 to move back into its closed position, therefore preventing the hose to collapse.
P.sub.c(x)=F.sub.h(X)+F.sub.s[2]

(14) Alternatively, the pressure interface 116, 216 may comprise an actuator (not shown) that is adapted to transfer a force proportional to the hydrostatic pressure P.sub.h-x provided by the external fluid (not shown) to act on the valve member 112, 212 supplementing the biasing force provided by the biasing member 110, 210 (e.g. spring force provided by a compression spring). The actuator may simply be a plunger arranged within the housing 102, 202 so as to transfer the hydrostatic pressure P.sub.h-x of the external fluid onto the downstream surface 122, 222 of the valve member 112, 212.

(15) In yet another alternative arrangement, the actuator (not shown) may be an indirect actuator (not shown) which may comprise an external sensor, adapted to measure the hydrostatic pressure of the external fluid and provide a signal to an actuator mechanism that is capable of providing an actuator force F.sub.a acting on the downstream surface 122, 222 of the valve member 112, 212 to supplement the biasing force of the biasing member 110, 210. The actuator force F.sub.a generated by the actuator mechanism (not shown) may be proportional to the hydrostatic pressure P.sub.h-x of the external fluid.

(16) In yet another alternative arrangement, the check valve assembly 100, 200 may comprise a snap-action mechanism (not shown) that is adapted to independently move the valve member 112, 212 into the open and/or closed position at a predetermined condition. The predetermined condition may be a distant threshold between the valve member 112, 212 and the final position of the valve member 112, 212 when in the open position and/or closed position. For example, magnetic elements may be used to provide a pulling force acting on the valve member 112, 212 towards the open and/or closed portion at a predetermined threshold distance.

(17) It is understood by the skilled person in the art that the predetermined constant spring force F.sub.s provided by the biasing member (e.g. compression spring) 110, 210 is made suitable to be operable at any subsea depth, so that the check valve assembly 100, 200 may be reliably used at any subsea depth. It is further understood by the skilled person in the art that the biasing force that is suitable to urge the valve member 112, 212 toward the valve seat surface 114, 214 may be provided by any suitable biasing member 110, 210.

(18) FIG. 7 shows an alternative aspect of the present invention in the form of a stab connector 300 that may comprise a check valve assembly in accordance with any one of the first and second embodiment of the present invention.

(19) In this particular example, the stab connector 300 incorporates a variation of the second embodiment of the check valve assembly 200 within its housing 302. During operation, the stab connector 300 is coupled to a hose (not shown) and extended to a subsea location, where a diver or Remotely Operated Vehicle (ROV) inserts the stab connector 300 to a female coupling so as to form a fluid path between the hose and the interior of the pipeline. A pressure interface 316 is provided at the distal end of the stab connector 300 such that it is in fluid communication with the external fluid when the stab connector 300 is locked in the female coupling. When the internal hose pressure P.sub.1 exceeds the cracking pressure P.sub.c(x) provided by the spring force F.sub.s and the hydrostatic pressure P.sub.h-x at subsea depth X, the valve member 312 moves into its open position, therefore creating a flow path between the inlet port 306 and the outlet port 308 of the stab connector 300.

(20) It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims.