GB2340917A

GB2340917A - Valve with metal to metal sealing

Info

Publication number: GB2340917A
Application number: GB9916144A
Authority: GB
Inventors: Richard James Pond
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-21
Filing date: 1999-07-12
Publication date: 2000-03-01
Anticipated expiration: 2019-07-12
Also published as: GB9818175D0; GB9916144D0; GB2340917B

Abstract

A valve comprises a housing formed from parts 1 and 2. An operating shaft 3 is rotatably mounted in the housing part 1 and carries a metal valve gate 4 which slides in continuous metal to metal contact on a metal valve seat 5. Seat 5 forms part of a valve chamber 6 having an inlet 7 and outlet 8. Valve gate 4 incorporates a port which can be moved into communication with outlet passageway 8 upon rotation of the shaft 3. Shaft 3 is rotated by means of an external tee-bar 10. Shaft 3 has an angled shoulder 13 which provides a metal to metal seal against an angled seat of the housing part 1. Metal gate buttons (21, figure 6) may be provided to give a continuous metal to metal sealing contact with the seat. A metal lip 16 which acts as a seal may be provided on one of the housing parts. The lip is acted on by internal pressure to enhance sealing.

Description

2340917 Improvements relatinq to Valves Where a valve may be inactive and

holding pressure for long periods of time (for example in subsea use) needle and ball valves have inherent disadvantages. In the case of a needle valve there can be the build up of particle debris between a needle and a seat which can cause sealing failure on subsequent operation. A ball valve is also susceptible to failure because of its reliance on back up resilient sealing.

According to the present invention there is provided a valve for controlling fluid supply and comprising a sealed housing through which passes an operating shaft carrying metal valve gate buttons or a single gate which slides over a metal valve seat within a chamber forming part of the flow passageway of the valve, the valve gate buttons or gate being slidable by rotary movement of the shaft between positions wherein the valve gate respectively opens and closes a passageway to or from said chamber, the valve gate buttons or gate and the valve seat being in continuous metal to metal sealing contact over the extent of movement of the valve gate buttons or gate.

This rotary valve has the valve gate buttons or gate in constant contact with the valve seat which provides a selfcleaning action when operated so that there should then be no need necessarily for secondary resilient sealing back-up. Furthermore there is no volumetric displacement during 2 operation of the valve, which accordingly simplifies the design for subsea applications.

The arrangement of the invention allows metal sealing in either of two directions. An alternative configuration using a third port allows a block before bleed or block after bleed system.

In the preferred design the operating shaft has an angled shoulder on the stem which metal to metal seals with an internal angled seat of the housing. Pressurisation is created by internal pressure application to the shaft area and since the shaft rotates it is always in sealing contact. A back-up resilient shaft seal may be provided around the shaft where it passes through the housing purely as a fail safe feature as this seal should normally never see any pressure. An outer seal provided as a scraper seal will also prevent ambient sea water from entering the valve when there is reduced internal pressure.

The shaft ideally carries a external operating tee-bar, or ROV (Remotely operated Vehicle) paddle for ease of operation. Preferably the external portion of the shaft leading to the tee-bar carries a stop bar which acts with end stops on the housing to limit the extent of rotation of the shaft. This prevents any high torque loading from being transferred to the internal parts of the valve once it is stopped out at the end of the operating stroke.

In the preferred arrangement the housing is formed from separate parts which are bolted together to enclose the valve gate, with a metal lip being formed on one of the 1 3 parts which is forced into an opening in the other part to act as a seal, such that the lip is subjected to internal pressure to enhance the operation of the seal.

The valve can incorporate a second valve gate which slides over a valve seat on another part of the chamber between positions wherein the second valve gate respectively opens and closes a second passageway to or from said chamber, thus making it seal in either of two directions To prevent the gate from moving from its end stop positions, a spring-loaded detent plunger may be arranged in the gate holder which locates into recess dimples in the valve body.

A separate metal seal ring between body and seat can provide for metal sealing containment.

With gate to seat and stem sealing, the overall valve design provides 100% continuous metal to metal sealing.

The invention may be performed in various ways and preferred embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure I is a vertical section through one preferred form of valve of this invention; Figure 2 is a horizontal section on line II-II of Figure 1; Figure 3 is a vertical section through an alternative form of valve of this invention; Figure 4 is a horizontal section through a modified form of valve gate to that valve shown in Figure 1; 4 Figures 5 and 6 illustrate an isolation valve of the invention in open and closed conditions respectively; Figure 7 is a section on line VII-VII of Figure 6; Figures 8 and 9 illustrate a block-before-bleed valve of the invention in open and closed conditions respectively; Figure 10 is a section on line X-X of Figure 8; Figure 11 is a section on line XI-M of Figure 8; and Figure 12 is a section on line XII-XII of Figure 10.

The valve assembly shown in Figure 1 is enclosed within a housing formed from parts 1 and 2. An operating shaft 3 is rotatably mounted in the housing part 1 and carries a metal valve gate 4 which slides on a metal valve seat 5 forming part of a valve chamber 6 having an inlet passageway 7 and an outlet passageway 8. The valve gate 4 incorporates is a port 9 which can be moved into communication with the outlet passageway 8 upon rotation of the shaft 3. The shaft 3 is rotated by means of an external tee-bar 10. This external part carries limit stops 11 which co-operate with pins 12 to determine the extent of rotation of the shaft 3.

The shaft 3 has an angled shoulder 13 which provides a metal to metal seal against an angled seat of the housing part 1. A back-up resilient seal 14 is provided, but may prove to be unnecessary. A crud or scraper seal 15 is provided on the outside face to act as a barrier to ambient conditions.

A metal lip 16 is formed on the housing part 2. This is forced into an opening in the housing part 1. Once parts 1 and 2 are bolted together internal pressure energises the tubular configuration of the lip 16 to force the lip further into contact with the internal wall of the housing part 1.

Again a resilient back-up seal 17 is provided, but this may prove to be unnecessary.

The arrangement shown in Figure 3 is similar in many ways to that of Figure 1. However the housing incorporates an additional central portion 18 and the valve chamber 5 houses an additional valve gate 19 which is also carried by the operating shaft 3. The valve gate 19 incorporates a port 20 which can be aligned, by rotation of the shaft 3, with the passageway 7. This dual gate arrangement allows for bi-directional flow.

As shown in Figure 4 the gate 4 can incorporate a slotted porting 21 allowing the valve, during closure, firstly to block the downstream port before venting the downstream port to a secondary port. This provides a block and bleed facility. A further modification would be to incorporate a second in-line valve seat and valve gate to provide a double block and bleed facility.

In the examples shown in Figures 5 to 7 and Figures 8 to 12 parts similar to those in Figures 1 and 3 are given identical reference numbers. The tee-bar 10 has been omitted from Figures 6, 9 and 10.

In the arrangement of Figures 5 to 7 the isolation valve incorporates spring-loaded metal gate buttons 21 for covering the openings to the inlet and outlet ports 7 and B. The springs provide for initial preload for low pressure sealing. Two ports 22 and 23 in the valve gate 4 allow for 6 full open flow when aligned with the ports 7 and 8. A metal ring seal 24 is provided between the housing parts 1 and 2. A spring-loaded detent plunger 25 locates in dimples in the valve body to hold the gate in its stop end positions.

Figures 8 to 12 show a valve provided with a block and bleed facility. In the valve-closed position shown in Figure 9 the outlet 8 is vented to bleed through a bleed port 26 via a channel 27 in the metal valve gate 4. Again a spring-loaded detent plunger 25 is provided.

I 7

Claims

1. A valve for controlling fluid supply and compris- ing a sealed housing through which passes an operating shaft carrying metal valve gate buttons or a single gate which slides over a metal valve seat within a chamber forming part of the flow passageway of the valve, the valve gate buttons or gate being slidable by rotary movement of the shaft between positions wherein the valve gate respectively opens and closes a passageway to or from said chamber, the valve gate buttons or gate and the valve seat being in continuous metal to metal sealing contact over the extent of movement of the valve gate buttons or gate.

2. A valve according to Claim 1, wherein the operat ing shaft has an angled shoulder on the stem which metal is seals with an internal angled seat of the housing.

3. A valve according to Claim 2, wherein a back-up resilient shaft seal is provided around the shaft where it passes through the housing.

4. A valve according to any one of Claims 1 to 3, wherein the shaft carries an external operating tee-bar or paddle.

5. A valve according to Claim 4, wherein the external portion of the shaft leading to the tee-bar or paddle carries a stop bar which acts with end stops on the housing to limit the extent of rotation of the shaft.

6. A valve according to any one of Claims 1 to 5, wherein the housing is formed from separate parts which are bolted together to enclose the valve gate, with a metal lip 8 being formed on one of the parts which is forced into an opening in the other part to act as a seal, such that the lip is subjected to internal pressure to enhance the operation of the seal.

7. A valve according to any one of Claims 1 to 6 including a second valve gate which slides over a valve seat on another part of the chamber between positions wherein the second valve gate respectively opens and closes a second passageway to or from said chamber.

8. A valve according to any one of Claims 1 to 7, wherein a spring-loaded detent plunger is arranged in the gate holder to locate into recess dimples in the valve body.

9. A valve according to any one of Claims 1 to 8, provided with a separate metal sealing ring between the body is and seat to provide for metal sealing containment.

10. A valve substantially as hereinbefore described and as illustrated in any one of the examples shown in the accompanying drawings.