GB2122313A - Improvements in or relating to valves - Google Patents

Abstract

A multiple stage valve (1) is described. The valve comprises a valve member (3) and a valve seat (2) each formed with a plurality of steps (3a to 3e and 2a to 3e) increasing in diameter in an upstream direction from the valve, the steps being configured so that a straight line can be drawn between opposed steps in all open positions of the valve and so that the flow passage varies in width, being narrowest in the regions of opposed steps. The valve member is pressure balanced in the closed position. <IMAGE>

Description

SPECIFICATION Improvements in or relating to valves This invention relates to improvements in or relating to valves in particular to a multiple stage high pressure valve for handling fluids, particularly gases, but also liquids.

To meet increasingly sophisticated problems, industry has insisted on higher and higher pressures.

This has been accompanied by a greater range of problems in handling higher pressure drops and fluid velocities. The Applicant's U.S. Patent 4,363,464, granted December 14, 1982 is concerned with such problems and describes a multiple stage stepped valve wherein the steps are of basically the same diameters.

Avalve having varying diameter steps is not, per se, new. For instance, U.S. Patent 3,485,474 to Baumann issued December23, 1969, relates to an adjustable fluid restrictor having progressigely increasing size stages. Valves of this type have a number of drawbacks. Among these are the following: actuation is from the small end of the steps series; there is no balancing of pressures acting against the stepped valve member at closed position; the valves are not readily disassembled, particularly in the field; each step typically co-operates with only a single other step and often it is difficult to tell from the exterior of the valve the position of the stepped valve member.

It is an object of the present invention to overcome or at least mitigate the disadvantageously previously proposed stepped valves.

According to one aspect of the present invention, there is provided a valve, comprising a valve member formed with a plurality of steps and a valve seat formed with a plurality of steps corresponding to the steps of the valve member, the steps being such that, when the valve is in an open condition, a straight line can be drawn between the steps of the valve member and the steps of the valve seat without contacting the steps.

According to a second aspect of the present invention, there is provided a valve comprising a valve member formed with a plurality of steps, a valve seat formed with a plurality of steps corresponding to the steps of the valve member and means for providing a pressure balance across the valve member when the valve is in a closed condition.

In a third aspect, the present invention provides a valve, comprising a valve body, a pod slidably insertable into a bore formed in the valve body and a seat member provided at an end of the bore, the pod including an operative assembly comprising a member in the form of a plug having an end portion for co-operating with the seat member, a closure sleeve slidably received in the bore and having a keyed relationship with the plug, means for preventing turning movement of the closure sleeve relative to the valve body and an operating stem projecting into the valve body and having a threaded connection with the plug to cause axial movement of the plug upon rotation of the stem.

For a better understanding of the present inven tion, and to show how the same may be put into effect, reference will now be made to the accom panying drawings, in which: Figure 1 is a vertical midsectional view through an angle globe valve embodying the invention, show ing the valve member plug in split view, with the upper portion closed, while the lower portion is partially open; Figure 2 is a top view of an actuating end of the vavlve; Figure 3 is a side elevational view of an outlet side of the valve, and Figure 4 is a bottom view of an inlet end of the valve.

Referring now to Figure 1, a multistage angle valve has a tubular valve body 1 formed with a main bore B of circular cross-section, in which a valve pod fits.

The pod includes a seat member 2 and an operative assembly A, which co-operates with the seat member in controlling the flow of fluid through the valve.

The seat member fits against a shoulder 40 on the body and has a boss 42 projecting into an inlet opening 44 formed in the body 1. An O-ring 21 forms a seal between the seat member and the body at the shoulder.

The seat member is interiorly formed with a series of indented female steps 2a, 2b, 2c, 2d and 2e merging with an inlet bore 48 communicating with thue inlet opening 44. The steps are of progressively increasing diameter proceeding from right to left as the parts are shown in Figure 1.

The operative assembly A comprises a number of parts, a primary one of which is a cylindrical valve member in the form of plug 3 terminating in a frusto-conical head portion defined by a series of indented male steps 3a, 3b, 3c, 3d and 3e. The male steps cooperate with female steps 2a to 2e in a manner which will be explained hereinafter.

The portion of the plug 3 to the left of the male steps 3a to 3e which is hollow and slidably fits within a closure sleeve 5 has keys 60 fitting within keyways 62 formed on the interior of the closure sleeve to permit longitudinal but prohibit turing movement of the plug relative to the sleeve. The closure sleeve 5 abuts against a tubular portion 66 of the seat member 2. Plural Teflon (Registered Trademark) O-rings 22 are provided on the interior of portion 66 and provide cushioning guides for the tubular portion of the plug.

At assembly, the closure sleeve 5 is slidablyfitted into the main bore B of the body 1 until the right hand end of the closure sleeve 5 abuts against the seat member 2. The closure sleeve 5 is so oriented that a pair of dowel pins 18 on the sleeve fit within recesses 69 on the body, to prevent turning movement of the closure sleeve relative to the body. The sleeve 5 is retained in place by a bonnet 6 which has a buttress threaded fit at 70 with the body.

The pod further includes a screw stem 4 whose right hand portion 71 defines a piston slidably received within the tubular portion of the plug 3. One or more seals 13 are provided on the piston to effect sealing contact between the piston and the tubular portion of the plug. The stem has acme threads 73 that engage complementary threads on the interior of the tubular portion of the plug, so that rotary movement of the stem is translated into longitudinal movement of the plug.

A collar 75 is formed on the stem and has a thrust relationship with a shoulder 77 on the closure sleeve 5 via a thrust washer 9. The stem has a shaft portion 81 rotatably extending through a bore in the left hand end of the closure sleeve 5 in sealing relationship thereto by means of seals 15 and 17. A nut 11 threads on the shaft portion 81 and bears against a thrust washer 10 interposed between the nut and the left hand end of the closure sleeve 5. The contact pressure between the thrust washers 9 and 10 and the parts with which they are associated, is determined by the tightness with which the nut 11 is threaded on the stem 4. The adjusted position of the nut 17 is maintained by the collar portion of a handle 20, which is detachably secured (such as by clamping) onto the shaft portion 81.The handle facilitates turning movement of the stem but may be removed and power actuation of the stem achieved in any desired fashion by a connection to the shaft portion.

The part are designed so that the plug is moved from its closed position to its fully open position by three turns of the handle 20. A spiral groove on an indicator plate 8 radially shifts an indicator slide 26 along an arm 91 on the handle 20. The indicator plate is adjustably secured to the bonnet 6 by screws 19 which, when loosened, enable circumferential adjustment of the indicator plate at assembly time, so that there is correspondence between the spiral groove of the indicator plate and the position of the plug 3 relative to the seat member 2. A spring biasing arrangement at 7 urges a pin-like shank portion 27 of the slide indicator into the groove of the indicator plate 8.

The relationship of the parts is such that one turn of the handle 20 will move the plug 3 an axial or longitudinal distance equal to the width of one step.

In the particular embodiment of the valve shown, the distance the plug moves from its fully opened position to its fully closed position is equal to the width of three steps. Figure 1 shows a plug in split view with the upper half being in its closed position, but the lower half being in its two-thirds open position. The position of the slide indicator 26 has been chosen to correspond to the closed position of the plug, so that the slide indicator is in its inwardmost position as the parts are shown in Figure 1.

When a differential pressure exists across the valve member or plug 3, such as when it is closed, a pressure force-balance is provided for across the plug by conducting fluid from the outlet side of the plug to a chamber 124 provided between the collar 75 and the left hand end face of the tubular portion of the plug 3. The chamber communicates with an outlet 132, when the valve is closed, by means of a groove 125 formed in the exterior of the plug 3.

An axial bore 126 extends from step 3c to a chamber 128 provided between the piston portion 71 of the valve stem and a blind interior end face 130 of the tubular portion of the plug 3. Thus, while the pressure in the inlet 44 may be quite high, relative to whatever pressure exists in the outlet 132, the thrust of this pressure to the left against the plug 3 is balanced and offset by the sum of the forces created by the pressure in the chamber 124 acting against the left hand end face of the tubular portion of the plug 3 and the pressure in the chamber 128 acting against the blind interior end face 130 of the plug.

There is a primary sealing means at 14, between the exterior of the closure sleeve 5 and the bore B in the body. There is a back up seal 16 provided between the closure sleeve and the interior of the valve body. Between seals 14 and 16, a bleed port 140 is provided. Should the seal 14 commence to fail, fluid will leak past the seal and exit through the bleed port and alert the operator of the imminence of failure of the seal.

The base of the closure sleeve is formed with an extension bleed passage 142, aligned with passage 140. Should the primary seal 15 commence to fail, seal 17 serves as a back-up. Fluid leaking past seal 15 will travel through ports 142 and 140 and exit to alert the operator of a seal problem.

The valve outlet 132, which has its axis angularly related to the axis of the inlet 44, leads into an annular chamber 146 formed around the interior of the valve body. Plural slots 148 are formed in the tubular portion of seat member 2 to provide for communication between the inlet and outlet when the plug is open to any extent. The slots 148 are distributed circumferentially around the tubular portion of the plug 3 to achieve 360 degrees of inlet-outlet communication when the plug is unseated.

Preferably a singered metal micropore filter is provided across the chamber 128 to prevent access of solids to the remainder of the interior of the tubular portion of the plug 3.

In operation, when the plug is in its closed position, the plug step 3d, which has a beveled corner, engages solidly against the edge of the seat member step 2d, while the unbeveled plug steps 3a to 3c are in close proximity to the corresponding seat member steps 2a to 2c. In practice, the diameters of the seat member steps 2a to 2c are made slightly less than the diameters of the corresponding plug steps, to assure that sealing contact occurs at the fourth step, step 2d in the arrangement shown in Figure 1.

Plug step 3e also has a beveled corner, and is of slightly larger diameter than the interior diameter of the seat member step 2e, but the axial spacing is such that it is slightly spaced from the corner of the seat member step 2e when plug step 3d is in sealing engagement with the corner of seat step 2d. However, as wear occurs between the steps 3d and 2d, plug step 3e eventually will make contact with seat step 2e to continue effective closure action of the plug 3, despite significant wear having occurred.

As can be seen from Figure 1, the steps 2a to 2e and 3a to 3e are arranged such that a straight line can be drawn between the steps of the plug 3 and the steps of the seat 2 without contacting the steps.

Note that each of the steps on the plug 3 co-operates with plural steps on the seat member 2, not merely a single step. For example, plug step 3a, in the closed position of the valve, co-operates with seat step 2a and continues to do so as the valve is cracked. Then, as it passes seat step 2b, it creates a restriction, and later does the same with seat step 2c and finally comes to a rest position opposite step 2d.

Further note that with the construction of the steps as shown, while there are successive zones of restriction (as the valve opens and closes), and these are aligned conically with one another. However, the reverse tapering of both interior and exterior steps creates a deflected and, therefore, tortuous path flow pattern through the valve.

The valve is ideal for handling gases because as the gas pressure decreases the gas volume increases. With the expanding, that is the varying size, step design, approximately equal amounts of pressure reduction are achieved at each stage. The valve may provide an ideal let down for high pressure water (such as is required for water injection). In this case, since the water does not expand with reduced pressure, each successive stage, having greater flow space, will take less pressure loss. It would appear that maximum capacity will be reached, with the seat configuration shown, at one and one-halfturns.

This is not true when gases are handled.

Thus, a valve embodying the invention overcomes or at least mitigates the problems of previous stepped valves because it is actuated from the wide side of the steps, making a number of advantages possible including a pressure force balance. The valve also includes a pod concept in which a seat member and an actuating assembly fit within a bore of uniform diameter adapting the operative parts of the valve to installation in a number of body configurations. However, the stepped portion of the valve member may be detachably connected to an actuating portion for ready replacement of the stepped portion when significant wear occurs. The valve also has an indicator for indicating the position of the valve member.

Claims (14)

1. Avalve, comprising a valve member formed with a plurality of steps and a valve seat formed with a plurality of steps corresponding to the steps of the valve member, the steps being such that, when the valve is in an open condition, a straight line can be drawn between the steps of the valve member and the steps of the valve seat without contacting the steps.

2. Avalve comprising a valve member formed with a plurality of steps, a valve seat formed with a plurality of steps corresponding to the steps of the valve member and means for providing a pressure balance across the valve member when the valve is in a closed condition.

3. A valve according to claim 1 or 2, wherein the steps are of indented serrate form.

4. A valve according to claim 1, 2 or 3 wherein the valve member is mounted so as to be movable, in use, over a distance in which each step of the valve member passes more than one step of the valve seat.

5. A valve according to any preceding claim, wherein the steps are arranged such that the dimensions of the valve member and the valve seat transverse to the direction in which the valve member is movable increase in steps in a direction parallel to the direction in which the valve member is movable.

6. A valve according to claim 5 wherein actuating means for the valve member are disposed nearer to the part of the valve member having the larger transverse dimensions than to the part having the smaller transverse dimensions.

7. Avalve, comprising a valve body, a pod slidably insertable into a bore formed in the valve body and a seat member provided at an end of the bore, the pod including an operative assembly comprising a valve member in the form of a plug having an end portion for co-operating with the seat member, a closure sleeve slidably received in the bore and having a keyed relationship with the plug, means for preventing turning movement of the closure sleeve relative to the valve body and an operating stem projecting into the valve body and having a threaded connection with the plug to cause axial movement of the plug upon rotation of the stem.

8. A valve according to claim 7, wherein the closure sleeve has a restricted portion and the stem has a collar disposed on one side of the restricted portion, a nut provided on the opposite side of the restricted portion threadedly engaging the stem to establish a thrust relationship between the stem and the restricted portion.

9. A valve according to claim 7 or 8 wherein a bonnet is threadedly received by the valve to retain the assembly within the bore.

10. A valve according to claim 7, 8 or 9 wherein the stem has a handle for facilitating rotation of the stem.

11. Avalve according to claim 7, 8,9 or 10, wherein means are provided for indicating the position of the plug relative to the seat.

12. Avalve according to claim 7,8,9 10 or 11, wherein the stem projects into the body and is threadedly connected to the valve member, means are provided to establish a sealing relationship between the stem and the body, and peripheral key means are provided on the valve member between the sealing means and the end of the valve member arranged to co-operate with the valve seat to engage fixed keyways to prevent turning movement of the valve member so as to translate rotary movement of the stem into axial movement of the valve member.

13. A valve substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. Any novel feature or construction of features described herein.