GB2275757A

GB2275757A - Flow control valves

Info

Publication number: GB2275757A
Application number: GB9304168A
Authority: GB
Inventors: David Mcsorley
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-03-02
Filing date: 1993-03-02
Publication date: 1994-09-07
Anticipated expiration: 2013-03-02
Also published as: GB2275757B; GB9304168D0

Abstract

A check valve (10) comprises: a valve body (12) defining a flow passage (14) therethrough; a valve member (22) located in the body (12), the valve member (22) defining a flow passage (24) therethrough for communication with the valve body flow passage (14) and being rotatable relative to the valve body (12); and a check member (38) mounted in the valve member (22) and arranged to permit flow through the valve member flow passage (24) in one direction and prevent flow in the opposite direction. The valve member (22) is rotatable to reverse the orientation of the check member (38) relative to the valve body (12) such that the valve (10) may be selectively utilised to check flow in opposite directions. The valve member (22) engages seats which may be retractable (Fig. 5) to facilitate its removal from and insertion into the body (12). <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO VALVES This invention relates to improvements in or relating to valves. One aspect of the invention relates to check valves, and another aspect of the invention relates to top-entry valves.

Check valves are utilized where it is desired to permit flow through a pipeline in one direction, but prevent flow in the opposite direction. It is an object of one aspect of the present invention to provide an improved check valve.

Ball valves are commonly used in many applications, including subsea pipelines used in offshore oil and gas extraction. Such valves generally operate in a satisfactory manner, though if the valve requires repair, dismantling and reassembly of the valve is relatively complex and involves removal or fitting of a large number of parts. Clearly, in subsea applications, where repairs must be carried out by divers operating in very difficult conditions, such repairs are difficult and take a considerable time and therefore tend to be very expensive. In some circumstances it may be easier to remove the valve for repair on the surface, though the removal and refitting of the valve are still difficult and time consuming operations.

Top-entry valves are generally easier to repair than ball valves, though the quality of seal obtained with conventional top-entry valves is generally not acceptable for high pressure oil and gas pipeline applications.

It is among the objects of a further aspect of the present invention to obviate or mitigate such disadvantages by providing a top-entry valve having improved seal quality According to a first aspect of the present invention there is provided a check valve comprising: a valve body defining a flow passage therethrough; a valve member located in the body, the valve member defining a flow passage therethrough for communication with the valve body flow passage and being rotatable relative to the valve body; and a check member mounted in the valve member and arranged to permit flow through the valve member flow passage in one direction and prevent flow in the opposite direction, whereby the valve member may be rotated to reverse the orientation of the check member relative to the valve body such that the valve may be selectively utilised to check flow in opposite directions.

Thus, the valve of this aspect of the invention provides a bidirectional check valve. This allows use of a single pipeline provided with a check valve of the present invention to accommodate fluid flow in two directions where previously two pipelines provided with oppositely oriented check valves would have been required. This feature may be utilised in oil terminals, where the pipeline may be used with the valve in one orientation for unloading a tanker, and then in the opposite orientation for loading a tanker.

Preferably, the valve is piggable, that is with the check member in the open configuration a pig may pass through the valve. Conveniently, the check member is in the form of a swinging check disc, pivotally mounted in the body, and in the open configuration a surface of the disc is aligned with the wall of the valve member flow passage to provide support for a pig as it moves therethrough.

Most conveniently, the disc is pivotally mounted about a horizontal axis above the centre of gravity of the disc such that the disc tends towards the closed configuration, and requires a pressure differential, acting in said one direction, to move the disc to the open configuration. If the valve is to be piggable, the pivot axis is conveniently located above the valve member flow passage. Preferably, the disc is inclined to the vertical in the closed configuration such that the weight of the disc is always acting to close the disc. The disc may be further biassed to the closed configuration by a spring or the like.

The valve may be located between the ends of two aligned pipes and rotatable through 1800, or may be located at the intersection of four pipes, in which case the valve may be rotatable through 270 or 3600.

According to a second aspect of the present invention there is provided a top-entry valve comprising: a valve body defining a flow passage therethrough and a chamber intersecting the flow passage; a valve bonnet for closing an open end of the chamber; sealing members mounted on the valve body at the intersections of the valve body flow passage and chamber; and a valve member located in the chamber and removable therefrom on removal of the valve bonnet, the valve member defining a flow passage therethrough for communication with the valve body flow passage, the valve member further being rotatable relative to the valve body between open and closed positions, end portions of the valve member flow passage and portions of the valve body side wall defining sealing surfaces for selective sealing engagement with the sealing members when the valve member is in the open and closed positions, respectively, the sealing members each being retractable from an extended sealing configuration to permit rotation of the valve member between the open and closed positions.

This arrangement provides a valve in which the valve member is readily removable, but which still provides an effective seal between the valve body and valve member.

Preferably, the valve member is cylindrical. Most preferably, the member is rotatable through at least 900.

The valve member may further also be in accordance with the first aspect of the invention, to provide a top-entry bidirectional check valve.

Preferably also, the sealing members are annular and extend around the valve body flow passage at the respective intersections with the chamber. The sealing members may be moved between the extended and retracted positions by mechanical, electrical or fluid powered actuators, and may be biassed towards one position.

These aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a ball valve in accordance with a preferred embodiment of the first aspect of the present invention; Figure 2 is a sectional plan view of a valve in accordance with a further embodiment of the first aspect of the present invention; Figure 3 is a sectional view of a top-entry valve in accordance with a preferred embodiment of the second aspect of the present invention; Figure 4 is an end view of the valve plug of the valve of Figure 3; and Figure 5 is an enlarged sectional view of a sealing member of the valve of Figure 3.

Reference is first made to Figure 1 of the drawings, which illustrates a check valve 10 in accordance with a preferred embodiment of the first aspect of the invention. The valve 10 includes a substantially conventional valve body 12 defining a flow passage 14 and having end flanges 16, 18 for connection to appropriate pipe ends. The body 12 further defines a chamber 20, which intersects the passage 14. Located within the chamber 20 is a valve member in the form of a ball 22 which itself defines a flow passage 24. The upper and lower ends of the chamber 20 are closed by respective covers 26, 28, a stub shaft 30 being mounted on the lower cover 28 for rotatable mounting of the ball 22. A drive shaft 32 extends through the upper cover 26 for rotation of the ball 22. Appropriate annular seals 34 are provided for engaging the ends of the ball 22 and are located on seal retainers 36 mounted inside the chamber 20.

Located within the flow passage 24 is a check member in the form of a swinging check disc 38 which, under its own weight, tends to occupy a closed position in which the edges of a front face of the disc 38 abut an annular disc seat 40 mounted in the ball 22. The disc 38 is pivotally mounted about a horizontal pivot axis 42, the axis 42 being located above the flow passage 24 such that the disc 38 may swing to an open position in which the front face of the disc defines a wall portion of the substantially cylindrical passage 24. It will also be noted that the floor of the flow passage 24 defines a recess 44 adjacent the lower face of the disc seat 40 to accommodate the lower end of the disc 38, when in the closed position.

lower end of the disc 38, when in the closed position.

A spring (not shown) is also provided on the pivot axis 42 to bias the disc 38 to the closed position.

In use, the valve 10 allows flow in one direction, a positive pressure on the front face of the disc 38 pushing the disc from the closed position. Any back pressure or flow in the opposite direction will cause the disc 38 to move to the closed position. If it is desired to permit flow in the opposite direction the valve ball 22 is rotated through 1800 such that the front face of the disc 38 faces in the opposite direction.

Large pipe systems are typically periodically cleaned by passing a "pig" through the pipes. Such pigs are of slightly smaller diameter than the inner diameter of the pipeline and typically include guide wheels or rollers which engage the inner wall of the pipe at various spaced locations. The check valve 10 is configured to permit passage of a pig through the valve in the direction of permitted flow. The risk of the pig jamming in the valve is minimised by the substantially cylindrical form of the flow passage 24 and by the support provided by the front face of the disc 38 in the open position.

The valve 10 may be located between the ends of two pipes, or, as is illustrated in Figure 2 of the drawings, a valve 10a may be adapted for location at the intersection of four pipes. If the valve ball or plug is fully rotatable through 3600 the valve may be configured to provide checked flow in any one of four directions.

Reference is now made to Figure 3 of the drawings which illustrates a top-entry valve 50 in accordance with a preferred embodiment of the second aspect of the present invention. The valve comprises a valve body 51 which defines a flow passage 52 and a plug receiving chamber 54 which intersects the passage 52. The chamber 54 is substantially cylindrical and receives a valve member in the form of a valve plug 56 which is retained in the chamber 54 by a bonnet or top cover 58. A drive shaft 60 is fixed to the upper end of the plug 56 and extends through a corresponding opening in the cover 58. The valve plug 56 defines a flow passage 62 for communication with the passage 52 and rotation of the plug 56 through 900 closes the flow passage 52 through the body 51.

Similar to the valve 10 described above, the plug 56 includes a swinging check disc 64, and the plug 56 may be rotated to reverse the orientation of the disc 64 to provide a bidirectional check valve. Also, like the valve 10 described above, the valve 50 is piggable and in the open configuration, as illustrated in chain dotted outline in Figure 3, the disc 64 provides support for a pig as it travels through the valve. The location of the disc 64 in the open configuration may also be seen in Figure 4.

Both the lower end of the chamber 54 and the lower face of the top cover 58 are shaped to locate the plug 56 and respective bush bearings 66 and washers 67 are located therebetween. Various O-ring seals are also provided between the plug 56 and chamber wall, and further between the top cover 58 and the chamber wall and between the top cover 58 and the drive shaft 60.

Reference is now also made to Figures 4 and 5 of the drawings, Figure 4 illustrating the valve plug 56 looking along the axis of the flow passage 62, and Figure 5 illustrating a detail of a section of a sealing member 70 as will be described below.

Provision of an effective seal between the plug 56 and valve body is achieved by means of retractable sealing members 70 which engage corresponding sealing surfaces 72, 74 on the plug 56. The first set of surfaces 72, which are engaged by the sealing members 70 when the valve is in the open configuration, are provided around the ends of the flow passage 62. The second set of sealing surfaces 74 are of similar shape and are formed in opposing side walls of the plug 56. The sealing members 70 are each located in the valve body flow passage 52 where the passage intersects the plug chamber 54 and extend round the flow passage. Figure 5 shows one of the sealing members 70 in some detail, and it will be noted that the sealing member 70 is located in a stepped notch 75 in the wall of the passage 52.Figure 5 shows a sealing member 70 in the extended sealing position, in which the member seat 76 contacts the respective sealing surface along a seal line 78. Each sealing member 70 is normally biased into the extended position by a number of coil springs 80. Each sealing member further defines an annular piston 82 and, in the illustrated example, retraction of the member 70 is achieved by the application of differential pressures to the chambers 84, 86 on either side of the piston 82 via conducts 85, 87. The chamber 84 adjacent the plug 56 accommodates a number of light coil springs 88, the springs 88 being held in place by means of a annular collar 90 which is bolted to the body 50. The member 70 is provided with various seals 92, and also appropriate fire-safe gaskets 94.

In use, the sealing members 70 will normally be extended to engage an appropriate sealing surface 72, 74 to either provide a sealed pathway through the valve 50 or to close the valve 50. If the configuration of the valve 50 is to be changed, the sealing members 70 are retracted until the members 70 are clear of the plug 56 and the plug is then free to rotate through 90, 180, or 2700 to the appropriate position, when the sealing members 70 are extended once more.

In this particular example, the initial seal between the sealing member 70 and the appropriate surface 72, 74 is achieved by means of the coil spring 80, and once pressurised fluid is present in the valve the location of the seal line 78 between the sealing member 70 and the respective sealing surface 72, 74 provides a differential area 96 for line pressure on the member 70, which pressure urges the member 70 into tighter engagement with the surface.

If the valve plug 56 should become damaged or require maintenance it is relatively straightforward to remove the top cover 58 and retract the plug 56, using a jack if necessary. Of course, the sealing members 70 would first be retracted to allow withdrawal of the plug 56.

Thus, from the above description, it may be seen that this embodiment of the second aspect of the invention provides the advantages of a bidirectional piggable check valve, in a similar manner to the first described embodiment, and also provides a valve configuration which facilitates maintenance and repair, while providing an effective seal between the valve plug and valve body.

It will be clear to those of skill in the art that the above described embodiments are merely exemplary of the aspect of the present invention and that various modifications and improvements may be made to these embodiments without departing from the scope of the invention.

Claims

1. A check valve comprising: a valve body defining a flow passage therethrough; a valve member located in the body, the valve member defining a flow passage therethrough for communication with the valve body flow passage and being rotatable relative to the valve body; and a check member mounted in the valve member and arranged to permit flow through the valve member flow passage in one direction and prevent flow in the opposite direction, whereby the valve member may be rotated to reverse the orientation of the check member relative to the valve body such that the valve may be selectively utilised to check flow in opposite directions.

2. The valve of claim 1 wherein the valve is arranged to be piggable.

3. The valve of claim 1 or 2 wherein the check member is in the form of a swinging check disc, pivotably mounted in the body, and in the open configuration a surface of the disc is aligned with the wall of the valve member flow passage to provide support for a pig as it moves therethrough.

4. The valve of claim 3 wherein the disc is pivotably mounted about a horizontal axis above the centre of gravity of the disc such that the disc tends towards the closed configuration, and requires a differential pressure, acting in said one direction, to move the disc to the open configuration.

5. The valve of claim 4 wherein the pivot axis of the check disc is located above the valve member flow passage.

6. The valve of claim 3, 4 or 5 wherein the disc is inclined to the vertical in the closed configuration such that the weight of the disc acts to close the disc.

7. The valve of any one of claims 3 to 6 wherein the disc is biased to the closed configuration by a spring or the like.

8. The valve of any one of the preceding claims in which the valve is located between the ends of two aligned pipes and is rotatable through 180ç.

9. The valve of any one of claims 1 to 7 wherein the valve is located at the intersection of four pipes and is rotatable through 270 or 360 .

10. The valve as claimed in any one of the preceding claims wherein the valve is a top entry valve and further comprises: a chamber intersecting the valve body flow passage; a valve bonnet for closing an open end of the chamber; and sealing members mounted on the valve body at the intersections of the valve body flow passage and chamber, wherein the valve member is located in the chamber and removable therefrom on removal of the valve bonnet, the valve member further being rotatable relative to the valve body between open and closed positions, end portions of the valve member flow passage and portions of the valve body side wall defining sealing surfaces for selective sealing engagement with the sealing members when the valve member is in the open and closed positions, respectively, the sealing members each being retractable from an extended sealing configuration to permit rotation of the valve member between the open and closed positions.

11. A top entry valve comprising: a valve body defining a flow passage therethrough and a chamber intersecting the flow passage; a valve bonnet for closing an open end of the chamber; sealing members mounted on the valve body at the intersections of the valve body flow passage and chamber; and a valve member located in the chamber and removable therefrom on removal of the valve bonnet, the valve member defining a flow passage therethrough for communication with the valve body flow passage, the valve member further being rotatable relative to the valve body between open and closed positions, end portions of the valve member flow passage and portions of the valve body side wall defining sealing surfaces for selective sealing engagement with the sealing members when the valve member is in the open and closed positions, respectively, the sealing members each being retractable from an extended sealing configuration to permit rotation of the valve member between the open and closed positions.

12. The valve of any one of the preceding claims wherein the valve member is cylindrical.

13. The valve member of any one of the preceding claims wherein the valve member is rotatable through at least 90".

14. The valve member of claim 10, or claim 12 or claim 13 when dependent on claim 10, wherein the sealing members are annular and extend around the valve body flow passage at the respective intersections with the chamber.

15. The valve of claim 14 wherein the sealing members are movable between the extended and retracted positions by powered actuators.

16. The check valve substantially as described herein and as illustrated in Figures 1 and 2, or Figures 3, 4 and 5 of the accompanying drawings.

17. The top entry valve substantially as described herein and as illustrated in Figures 3, 4 and 5 of the accompanying drawings.