WO2004003411A1

WO2004003411A1 - A gate assembly

Info

Publication number: WO2004003411A1
Application number: PCT/GB2003/002052
Authority: WO
Inventors: Paul Shillito; John Craven
Original assignee: Oliver Valvetek Limited
Priority date: 2002-06-27
Filing date: 2003-05-14
Publication date: 2004-01-08
Also published as: AU2003227927A1; GB0214880D0

Abstract

A gate valve assembly has a body (1, 2) with a valve chamber (3) that intersects fluid conduit (9) therethrough. A valve gate (10) is disposed in the chamber for movement in a direction transverse to said conduit between open and closed positions. The gate is drive by a rotary actuator has an eccentric pin (23) that is received in a slot (22) of a sliding member to which the gate valve is connected. The eccentric pin and slot convert rotational movement of the actuator into a translation movement of the gate member. The direction of movement of the gate member is transverse to the axis of rotation of the actuator. The pin and slot connection permits operation of the valve through only one half turn. A rotational connection (21) between the sliding member (20) and the gate valve permits a two-part housing (1, 2) to be secured together in different orientations as required.

Description

A GATE VALVE ASSEMBLY

The present invention relates to a gate valve assembly.

Gate valves are commonly used in the gas and oil industry to isolate fluid lines in sub-sea well Christmas tree valve blocks. They comprise a sliding valve gate that is moved to open or close the fluid line and an actuating stem threadedly connected to the gate. Rotation of the stem is converted into linear sliding movement of the valve in order to operate the valve. A conventional gate valve requires multiple rotations of the actuating stem to move the gate from open to closed positions and vice versa.

Small bore gate valves used in the branch lines of sub sea-trees lend themselves to actuation by ROVs. However, it is desirable for all actuating stems of such gate valves in a tree to be oriented in the same direction so as to permit actuation of all the valves (if required) in a single ROV docking. The longitudinal axis of each actuating stem of the valve is parallel to the direction of movement sliding gate by virtue of the threaded connection and is therefore perpendicular to the longitudinal axis of the fluid flow line. This means that in trees where the fluid lines radiate in different directions from a main conduit additional elbow connections are required to ensure that all the actuator stems are oriented in the same direction.

Another problem with actuation of the valve by a ROV is that its large operating force capacity can cause internal damage to the valve assembly if the rotational torque required to operate the valve is exceed. In such instances the actuating stem shears and the valve is rendered inoperable.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

According to the present invention there is provided a gate valve assembly comprising a valve body with an axial fluid conduit therethrough, a valve gate member mounted in said body for movement in a direction transverse to said conduit between open and closed positions, a rotary actuator for effecting movement of the gate member between said open and closed positions, a connection between the actuator and the gate member for converting rotational movement of the actuator into a translation movement of the gate member, wherein the direction of movement of the gate member is transverse to the axis of rotation of the actuator. Preferably the direction of movement of the gate member is substantially perpendicular to the axis of rotation of the actuator.

Ideally the connection is configured to move the gate member from open to closed positions or vice versa in response to substantially 180° rotation of the actuator. Thus only one half of a turn of the actuator is required to operate the valve.

A stop may be provided to prevent rotation of the actuator beyond 180°. The stop may be frangible if the rotational torque applied to the actuator exceeds a predetermined threshold. The actuator may have a radially extending member for abutment with the stop. The extending member in one embodiment is a plate having at least one edge for abutment with the stop.

The valve body is preferably a two-part housing with the gate member and fluid conduit disposed in one part and the actuator in the other part. There may be provided a rotatable joint between the actuator and the gate member enabling the two parts of the housing to be rotated relative to one another without breaking connection between the actuator and the gate member. The joint may be directly or indirectly connected between the actuator and gate member.

A sliding member may be connected between the actuator and the gate member, the sliding member being movable in translation with the gate member. The rotatable joint is preferably between the sliding member and the gate member.

The connection between the actuator and the gate member may comprise an eccentric member on said actuator and a slot associated with said gate member, the eccentric member being received in said slot. The slot is conveniently defined in said sliding member.

The eccentric member may be a pin that extends from an end of the actuator.

The housing may define a valve chamber in which gate member moves. Preferably the valve gate member is received between valve seat elements that support the gate member in its translation movement.

The actuator preferably comprises a stem assembly having a first end with means by which it can be rotated and the other end has eccentric pin for receipt in said slot.

Preferably the first end of the stem assembly projects from the housing. Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a longitudinal sectioned view through a gate valve assembly in accordance with the present invention;

Figures 2 to 4 are diagrammatic representation of the valve assembly of figure

I illustrating movement of the valve gate in response to rotation of an operating stem;

Figures 5a to 5c show three different assembled configurations of the valve assembly of figures 1 to 4;

Figures 6a to 6c are diagrammatic representations of an alternative embodiment of a sliding member and valve gate forming part of the present invention; and

Figures 7a to 7c are diagrammatic representations of a further alternative embodiment of a sliding member and valve gate forming part of the present invention.

Referring now to the figures 1 to 5 of the drawings, the exemplary sub-sea gate valve assembly has a two-part housing 1 , 2 that defines a valve chamber 3 in which a valve mechanism 4 is received. Each part of the housing has a cavity that defines half the valve chamber 3. The two parts of the housing 1, 2 are connected together by four studs 5 and nuts 6 (two only shown) and are provided with an interfacing metal seal 7.

A first part of the housing, known as the bonnet 2, has a vertical bore in which an operating stem assembly 8 is received. The second part of the housing 1 has a vertical fluid passage 9 for connection into the tree block. The passage 9 is intersected and divided into two by the valve chamber 3.

A valve gate 10 slidably disposed in the valve chamber 3 is designed to open or close the fluid passage 9. It comprises a generally rectangular member with a bore

I I therethrough. The gate 10 is supported between two annular seats 12 that are received in annular recesses in the chamber 3. The interior bores 13 of the seats 12 correspond in diameter to that of the fluid passage 9 and therefore effectively extend the fluid passage 9 across the chamber. The seats 12 are provided with annular seals 14.

In figure 1 the valve gate 10 is shown in the closed position whereby communication between the two parts of the passage 9 is blocked. Movement of the gate 3 to the left in figure 1 in a direction perpendicular to the longitudinal axis of the fluid passage 9 eventually brings the bore 11 in the gate 10 into coaxial register with the two parts of the fluid passage 9. This completes the passage and the valve is fully open.

The sliding movement of the valve gate 10 is driven by a sliding member 20 in the valve chamber 3, the gate being secured to the sliding member 20 by a cylindrical connection 21 of T-shaped cross section. The male member of connection is defined on the sliding member 20 and received in a complementary female slot in the valve gate 10.

An upper surface of the sliding member 20, distal from the valve gate 10, has a transverse slot 22 extending perpendicular to the direction of movement of the sliding member in the chamber 3. The slot 22 is intended to receive a pin 23 on the end of the operating stem assembly 8 (described below).

The operating stem assembly 8 has an inner stem 24 that extends into the vertical bore of the bonnet 2 and interfaces with the sliding member 20, and an outer stem 25 that extends out of the bonnet 2 and is connected to the inner stem 24. Both spindles are prevented from moving in an axial direction. The outer stem 25 is retained by a cover housing 26 that sits on the bonnet 2 and is supported for rotation by a first set of bearings 27. The upper end of the outer stem 25 projects from the cover housing 26 and terminates in a spindle 28 of square cross section. Such a spindle is intended for connection to an extension rod (not shown) of the kind that is designed to interface with a ROV panel and enable actuation of the stem assembly by the ROV. The inner stem 24 is supported for rotation in a bearing 29 and terminates in an eccentric pin 23 that is received in the transverse slot 22 in the sliding member 20. The pin 23 has a sleeve 30 to prevent galling between it and the sliding member 20.

The operating stem assembly 8 is sealed by a seal set 31 around the inner stem 24 and is retained in the bonnet 2 by the cover housing 26 and four capped screws 32 (one only shown in figure 1). A stop plate 33 is fixed to the spindle 28 for rotation with the stem assembly 8 and extends radially outwards. The plate 33 (shown most clearly in figure 5a) is formed from a circular disc that is cut-away to define two radial edges 34 for engagement with a stop pin 35 (shown only in figures 5a to 5c) that is upstanding from the cover housing 26. The interaction of the stop pin 35 and the plate 33 restrict the rotational movement of the stem assembly 8. In the position shown in figure 5a one of the edges 34 engages the stop pin 35 to prevent further rotation of the stem assembly 8 in the clockwise direction. From this position the operating stem assembly 8 can be rotated through 180 anticlockwise before the other edge 34 of the plate 33 engages the stop pin 35 and prevents further rotation in that direction.

Four capped screws 36 pass through the second part of the housing 1 and are used to mount the valve assembly on the tree.

The operation of the valve assembly will now be described with reference to figures 2 to 4. The diagram of figure 2 corresponds to the position of the valve gate 10 in figure 1 in which the gate bore 11 is out of register with the fluid passage 9 and therefore the valve is closed. In order to open the valve the spindle 28 is rotated so as to rotate the valve stem assembly 8. As the assembly rotates the eccentric pin 23 on the inner stem 24 moves relative to the slot 22 in the sliding member 20 and in a camming action it forces the sliding member 20 to translate to the left (see figure 3). The sliding member 20 carries the valve gate 10 with it and so the bore 11 is moves to the left and into communication with the fluid passage 9. Rotation of the stem assembly 8 through the full 180° allowed by the stop plate 33 and stop pin 35 brings the valve gate 10 to the limit of its travel and the bore 11 into full register with the fluid passage 9 as illustrated in figure 5c. The valve is now open and further rotation in the same direction is prevented by the abutment of one of the edges 34 of the stop plate 33 against the stop pin 35. In order to close the valve the stem assembly 8 must be rotated in the opposite direction until the other edge 34 of the plate 33 abuts the stop pin 35. The eccentric pin 23 and transverse slot 22 arrangement allows the valve to be moved from opened to closed positions simply through a half turn (180 degrees) of the operating stem. This makes it particularly suitable for actuation by a ROV.

The upper surfaces of the bonnet 2 and the stop plate 33 may bear indicators so that the status of the valve can be monitored by observing the rotational position of the plate. In the event that the excessive torque is inadvertently applied to the operating valve stem assembly the stop pin 35 will shear allowing the stop plate 33 and stem assembly 8 to continue rotating without damage to the internal components of the assembly. The eccentric pin 23 and slot 22 connection ensures that continued rotation of the stem assembly in one direction simply moves the valve gate backwards and forwards repeatedly in the valve chamber 3. In this instance the valve is still functional but it is necessary for rotation of the stem assembly to be stopped at the correct position in order to open or close the valve fully.

The provision of the cylindrical connection 21 between the sliding member 20 and the valve gate 10 permits them to be rotated relative to one another about the centre line indicated at X. This allows the bonnet 2 and the second part of the housing 1 to be rotated relative to each other through 360° and secured together (with the studs and nuts 22) in one of four different 90° offset orientations without affecting operation of the valve assembly as illustrated in figures 5a to 5c. The configuration illustrated in figure 5b corresponds to that shown in figure 1, whereas figures 5a and 5c respectively show the bonnet 2 rotated through 90° relative to first part of the housing in each direction. The facility to rotate the bonnet 2 and first housing member 1 relative to one another without affecting valve operation is advantageous for small bore gate valves used on sub-sea trees. It is desirable on such trees for the operating stem spindles of all the valves in a tree to be commonly directed so that a ROV can be used to actuate the valve in a single docking.

In an alternative embodiment of the invention shown in figures 6a to 6c the transverse slot 122 in the upper surface of the sliding member has an arcuate configuration rather than a rectilinear form. In figure 6a the valve is shown closed with the valve gate 10 sealing the fluid passage 9. The operating stem assembly (inner spindle 24 shown only) is rotated to rotate the eccentric pin 23 in the direction of the arrow. In figure 6b the stem assembly has rotated through approximately 45 degrees and valve is partially open. In figure 6c the valve is fully open with the stem assembly having been rotated through a full 180 degrees. This particular slot configuration provides for a non-linear relationship between the speed of travel of the gate 10 and the rate angular rotation of the operating stem assembly 8 and can therefore be used in applications where it is desirable to control the rate of flow of fluid through the valve. The arrangement provides for a relatively rapid initial gate movement to establish partial opening of the valve and communication with the fluid passage followed by relatively slow travel in bringing the bore into full register with the passage.

It is to be understood that the connection between the actuating stem assembly and the valve gate may take any appropriate form that provides conversion from rotational movement to translating movement and provides the potential for the gate to be moved from open to closed positions or vice versa in 180° of rotation of the stem assembly. One example of an alternative mechanism is illustrated in figures 7a to 7c. In this embodiment the eccentric pin 223 on the end of the inner stem 224 is connected to a sliding member 220 of reduced length by a link plate 240. One end of the link plate 240 is rotatably connected to the eccentric pin 223 and the other end is connected to a centrally mounted pin 241 on the sliding member 220. Rotation of the actuating stem assembly causes movement of the sliding member and valve gate 210 in the valve chamber 203 as before.

In all the embodiments the relationship between the rotation of the stem assembly and the motion of the valve gate is designed to be non-linear such that there is a higher mechanical advantage at the beginning of the stroke when the friction between the gate and the seats is at its highest.

It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the valve assembly may be used to control the flow of fluid through any flow line. Moreover, the transverse slot may be of any appropriate form.

Claims

1. A gate valve assembly comprising a valve body with an axial fluid conduit therethrough, a valve gate member mounted in said body for movement in a direction transverse to said conduit between open and closed positions, a rotary actuator for effecting movement of the gate member between said open and closed positions, a connection between the actuator and the gate member for converting rotational movement of the actuator into a translation movement of the gate member, wherein the direction of movement of the gate member is transverse to the axis of rotation of the actuator.

2. A gate valve assembly according to claim 1, wherein the direction of movement of the gate member is substantially peφendicular to the axis of rotation of the actuator.

3. A gate valve assembly according to claim 1 or 2, wherein the connection is configured to move the gate member from open to closed positions or vice versa in response to substantially 180 degrees rotation of the actuator.

4. A gate valve assembly according to claim 3, wherein a stop is provided to prevent rotation of the actuator beyond 180 degrees.

5. A gate valve assembly according to claim 4, wherein the stop is frangible when a predetermined rotational torque is exceeded.

6. A gate valve assembly according to claim 4 or 5, wherein the actuator has a radially extending member for abutment with the stop.

7. A gate valve assembly according to claim 6, wherein the extending member is a plate having at least one edge for abutment with the stop.

8. A gate valve assembly according to any preceding claim, wherein the valve body is a two-part housing with the gate member and fluid conduit disposed in one part and the actuator in the other part.

9. A gate valve assembly according to claim 8, wherein there is a rotatable joint between the actuator and the gate member enabling the two parts of the housing to be rotated relative to one another without breaking connection between the actuator and the gate member.

10. A gate valve assembly according to claim 9, wherein there is a sliding member connected between the actuator and the gate member, the sliding member being movable in translation with the gate member.

11. A gate valve assembly according to claim 10, wherein the rotatable joint is between the sliding member and the gate member.

12. A gate valve assembly according to any preceding claim, wherein the connection comprises an eccentric member on said actuator and a slot associated with said gate member, the eccentric member being received in said slot.

13. A gate valve assembly according to claim 12 when dependent from claim 10, wherein the slot is defined in said sliding member.

14. A gate valve assembly according to claim 13, wherein the eccentric member is a pin that extends from an end of the actuator.

15. A gate valve assembly according to claims 13 or 14, wherein fixing means are provided to secure the two parts of the housing together in one of a possible plurality of orientations.

16. A gate valve assembly according to any preceding claim, wherein the housing defines a valve chamber in which gate member moves.

17. A gate valve assembly according to any preceding claim, wherein the valve gate member is received between valve seat elements that support the gate member in its translation movement.

18. A gate valve assembly according to any preceding claim, wherein the actuator comprises a stem assembly having a first end with means by which it can be rotated and the other end has an eccentric pin for receipt in said slot.

19. A gate valve assembly according to claim 18, wherein the first end of the stem assembly projects from the housing.

20. A gate valve assembly according to claim 19 when dependent from claim 7, wherein the plate is disposed on the first end of the stem assembly for engagement with the stop.

21. A gate valve assembly according to any one of claims 1 to 11, wherein the connection comprises an eccentric member on said actuator and link member connected between the eccentric member and the valve gate member.

22. A gate valve assembly according to claim 21, wherein the link member is a link plate that is connected to the eccentric member and a pin associated with the gate member.

23. A gate valve substantially as hereinbefore described with reference to the accompanying drawings.