GB2105442A - Security device for a rising stem valve - Google Patents

Abstract

The device comprises a turning member 10 adapted to fit over the nut 14 of the valve, and being held in place by a security nut 18, a shroud 11 and a key 12 to effect turning movement of the nut 14, through cooperating coded projections 21 and recesses 32. The key has a plurality of detent balls 49 positioned in a bore 48 to project inwardly or outwardly of the wall of the key; when projecting inwardly the key may be inserted into or removed from the shroud, but when the key has been inserted and the outer ball 49 projects into a groove 27 provided in the shroud, the key is retained therein. Operation of the detent balls 49 is controlled by a drive member 13 which may be lifted against the bias of spring 47 by the stem 15 of the valve when the valve has been opened. The key 12 may thereafter be removed only when the valve has been closed again. <IMAGE>

Description

SPECIFICATION A security device for a rising stem valve This invention relates to a securing device for a rising stem fluid-flow control valve, and in particular to a device which has a key for operating the valve, arranged so that the key can be removed only when the valve has been fully closed.

Rising stem fluid-flow control valves are widely used in pipe-work installations, for the control of fluid flow along a pipe-line incorporating the valve.

Such a valve typically has a valve body in which is mounted a valve member arranged for sliding movement transverse to the axis of a passage formed through the valve body, the valve member being connected to a screw-threaded stem engaged with a nut suitably mounted for rotation on the valve body but held against movement along the axis of the stem. Typically, a handwheel is mounted on the nut to allow the nut to be rotated, thereby to drive the threaded valve stem and hence the valve member to open or close the valve, depending upon the sense of rotation of the nut.

When a rising stem fluid-flow control valve is closed, the free end of the rising stem normally lies closely adjacent the nut; to open the valve from this setting the nut is rotated in the appropriate sense to cause the stem to project by a greater extent from the nut, thus moving the valve member to open the passage through the valve body. When the valve is fully opened, the stem projects through the nut by the greatest amount.

In a pipe-line installation containing several rising stem fluid-flow control valves, it is often the case that any particular valve may be opened or perhaps closed only when some other valve is in a particular setting -- either opened or closed, as appropriate. For example, in the simplest case of an installation having but two valves, it may be that when one valve is to be opened, the other must first be closed, and vice-versa. In the past, it has been necessary to rely upon the workman ensuring that the correct sequence of valve operation occurs.Moreover, to prevent the operation of the valves by unauthorised personnel, not uncommonly the valve wheels are locked for instance by means of chain and padlock, and the use of padlocks with different keys has been employed in an attempt to ensure workmen do not operate the valves in an impermissible sequence, for example by insisting on a workman returning to a store one padlock key before issuing another key. However, such a system offers very little security against maloperation, and in any event just because a handwheel is locked by means of chain and padlock, there is no guarantee that the valve wheel has been locked with the valve in its correct setting.

It is an object of the present invention to provide a security device for a rising stem fluidflow control valve, which device will permit an operating key for the valve to be removed from the valve only when the valve has been fully closed, the key at all times being held captive so as to prevent its use in operating other valves.

According to this invention, there is provided a security device for a rising stem fluid-flow control valve, which device comprises a turning member adapted to be secured to the nut of the valve and having at least a portion of its external periphery of circular form, there being at least two arcuatelyspaced radial projections upstanding from said portion, a shroud adapted to surround with clearance of the turning member and provided with means to restrain rotation of the shroud with respect to the valve when fitted thereto, the shroud having an annular groove formed in the inwardly directed surface thereof, an operating key having a bore in which may be received the circular portion of the turning member and being adapted partially to fit within the shroud, the key having a plurality of recesses opening into the bore therein which recesses are appropriately positioned to receive the projections on the turning member when the key is fitted into the shroud to engage the turning member, the key also having a through-bore into which the rising stem of the valve may extend, detent means provided in the key and arranged for projection either into the through-bore in the key to such an extent as to lie in the path of the valve stem or beyond the outer periphery of the key for engagement in the groove in the shroud so as to prevent relative axial movement between the key and the shroud, and a detent drive member which has a section able to fit into the through-bore in the key, said section having a first portion of substantially the same diameter as the stem of the valve and a second portion defining an annular channel for receiving the detent means when not projecting beyond the outer periphery of the key, the detent drive member being adjustable to allow presetting of the distance between the annular channel of the detent drive member and the end face of said section thereof, the arrangement being such that when the device is fitted to a rising stem valve, said end face of detent drive member is engaged and moved by the rising stem as the turning member is operated by the key to open the valve from its fully closed setting, thereby moving the detent means to restrain withdrawal of the key from the shroud.

It will be appreciated that when the security device of this invention, the key will be retained within the shroud in engagement with the turning member whenever the valve is other than in its closed setting, because when the valve is partially or fully open, the valve stem projects from the nut by an extend greater than at the valve-closed setting, thus lifting the detent drive member such that the detent means is driven thereby out of the channel in the detent drive member and into the groove in the shroud. When so moved, the detent means holds the key against axial movement with respect to the shroud, and thus the key cannot be removed from the valve to which the security device is fitted.Conversely, as the valve is operated to its closed setting, the annular channel in the detent drive member comes into register with the detent means, allowing the detent means to move out of the groove in the shroud into the detent drive member channel, thus freeing the key and allowing its removal from the valve to which the security device is fitted.

The detent means preferably comprises a member mounted for movement in a radiallyextending bore formed in the key from the outer periphery thereof into the through-bore, the length of the member being selected having regard to the distance between the outer periphery of the key and the inner diameter of the through-bore which accomodates the rising stem, as well as the required projection of the member from the key to be accomodated in the groove in the shroud or in the channel in the detent drive member.

Conveniently, the member comprises a plurality of balls able to roll along the radial bore by a distance not greater than one half of the diameter of the balls, and the material of the key at the two ends of the radial bore being deformed slightly so as to prevent the balls leaving the bore.

It is preferred for there to be provided a plurality of similar detent means equi-spaced around the through-bore in the key, but in substantially the same radial plane. Conveniently, two or three such detent means may be provided, spaced at 180" or 1200, as appropriate.

In order to prevent unauthorised operation of the detent drive member it is preferred for the key to include an elongate axial housing which is able to accommodate both the rising stem of the valve, whatever the setting of the valve, and the detent drive member, which is engaged and lifted by the rising stem of the valve. To ensure that the detent drive member always is maintained in contact with the free end of the rising stem, it is preferred for there to be a compression spring disposed between the detent drive member and the end of the housing disposed furthest from the main body of the key.

Tests on relatively large scale rising stem fluidflow control valves have shown that the manufacturing tolerances are such that for different samples the precise relative disposition between the free end of the rising stem and a datum on the valve body tend to vary by quite a large amount, for any given setting of the valve - for instance closed. Accordingly, it has been proved necessary to provide in the security device of this invention means to accommodate these differences in manufacturing tolerances, whereby alignment of the annular channel in the detent drive member with the detent means can be assured when the valve is fully closed, so as to allow the key to be removed at that setting.A preferred form of detent drive member comprises a first component in the form of a threaded stub having formed at one end thereof a head adapted to fit within the through bore in the key and to be engaged by the free end of the rising stem of the valve, and a second component having a screw-threaded bore engaged with the threaded stub of the first component and having a boss which also fits within the through-bore in the key, the boss defining the annular channel of the detent drive member. Adjustment may then be effected by turning the first component with respect to the second component, and such adjustment should be performed during the initial installation of the security device on a rising stem valve.Then, a spacer of an appropriate thickness should be provided between the head at an end of the first component and the boss of the second component, which spacer has substantially the same diameter as the head so as to prevent erroneous operation of the detent means when the detent drive member is lifted by the rising stem to such an extent as the spacer is aligned with the detent means.

Not infrequently, a rising stem fluid control valve is installed such that the line of movement of the rising stem is other than vertically upwardly. If the security device of this invention is used with a valve installed such that the stem projects generally downwardly from the valve body, if the valve is operated by rotating the key, the key will fall out of the shroud as the valve becomes closed, because the detent means releases the key at that setting. It is therefore preferred for there to be provided a releasable catch which serves to retain the key in the shroud, even when the valve is closed, until such time as the catch is released.

Conveniently, the catch includes an element mounted in the key and the spring-urged to a position where the element may engage the groove provided in the shroud, an operating lever being provided to withdraw the element when desired from the groove.

This invention extends to a rising stem valve including a valve body, a nut rotatable with respect to the body and a threaded rising stem interengaged with the nut, in combination with a security device of this invention as described above with the turning member secured to the nut of the valve, and the shroud mounted in a nonrotatable manner on the valve body. Preferably, the shroud is indirectly mounted on the body by means of the turning member itself, the shroud being rotatably mounted on the turning member but held against axial movement with respect thereto, and the shroud having an abutment which engages the valve body to prevent rotation of the shroud with respect to the body.

By way of example only, one specific embodiment of a rising stem fluid-flow control valve security device constructed in accordance with this invention will now be described in detail, reference being made to the accompanying drawing, which is a cross-sectional view through the security device.

The illustrated embodiment of a security device of this invention comprises a turning member 10, a shroud 1 a key 12, and an adjustable detent drive member 1 3. The device is intended to be attached to the nut of a rising stem valve, which nut is shown diagrammatically at 14 and cooperates with a threaded rising stem 1 5. Rotation of the nut 14 causes the stem 15 to be moved with respect to the nut, thereby opening or closing the valve.

The nut 14 has a hexagonal outer profile, and the turning member 10 is provided with a hexagonal opening 1 6 whereby the turning member 10 may be fitted in a non-rotatably manner over the nut 14. The upper end portion 1 7 of the nut is externally threaded (normally to allow a handwheel to be secured to the nut) and a ring nut 1 8 is engaged with the treaded end portion 1 7 securely to hold the turning member 10 on the nut 14, the ring nut 18 being received in a stepped counter-bore 19 in the turning member 10.The ring nut 1 8 is provided with at least two radial projections 20 extending from its outer circular periphery, allowing the ring nut 18 to be driven by a tubular tool having an internal diameter substantially the same as that of the ring nut 18 and an outer diameter substantially the same as the larger inner diameter of the counter-bore 1 9, the tool also having appropriately disposed recesses to accommodate the projections 20.

Such a ring nut offers a high degree of security, and serves to render it exceedingly difficult to remove the ring nut other than with the correct tubular tool.

The tubular member 10 is provided with at least two projections 21 from its outer cylindrical surface 22, which projections in the present embodiment take the form of the hardened steel heads of bolts 23 (for instance, Allen screws) threaded into counter-bored radial bores provided in the turning member 10. Though in the illustrated example, the two projections 21 are arcuately spaced by 1800 C, the projections may be disposed at some other angle and also more than two projections may be provided: in this way, security can be enhanced by coding the relative disposition and number of the projections, as will be explained hereinafter.

The shroud 11 is of cylindrical form and surrounds with clearance the turning member 10.

The shroud has an inwardly directed flange 24 adjacent its lower end (in the drawing), which flange is rotatably received on a portion of reduced diameter of the turning member 10, the flange abutting a shoulder on the turning member between said reduced diameter portion and the major part of the turning member. The flange is retained on the reduced diameter portion of the turning member by means of a circlip 25, accessible only when the device is not fitted on a valve.

Depending from the shroud 11 below the flange 24, there is provided an abutment 26, which abutment is intended to engage a portion of a rising stem valve when the security device is fitted thereto, so as to restrain rotation of the shroud 11. Adjacent the other end of the shroud and formed in the inwardly facing surface thereof there is provided an annular groove 27, which groove is of symmetrical trapezoidal cross-section, being defined by two substantially linear side walls 27a and 27b, and a substantially linear base wall 27c. Drain holes 28, typically three in number, are provided at the bottom of the shroud, adjacent the flange 24, to allow any liquid entering the shroud to drain away.

When the above-described device is fitted to a rising stem valve, a key such as that illustrated at 1 2 must be employed to turn the nut 14, thereby to open or close the valve. The key 1 2 comprises a cylindrical body 30 having at one end a counter-bore 31 the internal diameter of which is substantially the same as the outer diameter of the turning member 10, the wall of the key 12 in the region of the counter-bore 31 is provided with two recesses 32, the size and angular disposition of which are suitable for accommodating the projections 21. Thus, the key 12 must specially be adapted to suit a particular turning member 10 and cannot be used in conjunction with a security device having its projections 21 coded differently, either in number or angular disposition.

Extending axially through the body 30 of the key 12 is a through-bore 33 the diameter of which is such that the rising stem 1 5 of the valve may be received therein. The upper end of the through bore 33 is also counter-bored, and a tubular sleeve 34 is positioned therein, the tubular sleeve being closed at its upper end 35. The sleeve 34 is locked in position by means of a grub screw 36, and a lead plug 37 is driven into the threaded bore in the body 30 accommodating the grub screw 36, so as to prevent access to that screw once it has been tightened home.

The adjustable detent drive member 1 3 comprises a first component having a threaded stub 40 extending from a head 41 and provided with a screw-driver slot 42 at its free end; and a second component comprising a cylindrical nut 43 threadingly engaged with the stub 40, the nut 43 having a boss 44 formed with an annular channel 45 which channel is of arcuate cross-sectional shape. Between the head 41 and the boss 44, there is provided at least one spacer 46. A radially-extending grub screw 47 is provided in the nut 43 to lock the first and second components against relative turning movement.

The adjustable detent drive member 13 is partially positioned in the through-bore 33, with the larger diameter portion of the second component 43 resting on the base of the counterbore in the body 30, a spring 47 being located between nut 43 and the end 45 of the sleeve 34, to urge the detent drive member to the illustrated position. When so located, the channel 45 is in alignment with at least one radial bore 48 provided in the body 30, in which bore is located a plurality of hardened steel balls 49. The ends of the bore 48 are peened over, so as to prevent the balls 49 leaving the bore, but the balls may project radially by a limited extent either from the outer surface of the body 30 or into the through-bore 33.

The length of the body 30, between the bore 48 and the counter-bore 31, is such that when the key 12 is fully engaged with the turning member 10, the bore 48 is in the same radial plane as the annular groove 27 in the shroud 11. Moreover, during the initial installation of the security device on a rising stem valve, the axial dimension of the spacer 46 of the adjustable detent drive member 1 3 is selected to be such that with the valve fully closed (and thus with the upper free end of the rising stem 1 5 closest the nut 41) the head engages the upper end of the rising stem 1 5 and the nut 43 also engages the base of its associated counter-bore: the channel 45 is thus aligned with the bore 48.The key therefore may freely be inserted into or lifted out of the shroud 11, because the innermost ball 49 may be received in the channel 45 of the detent drive member 13, and the outermost ball 49 will not project from the key.

However, upon engagement of the key with the turning member 10 and rotation thereof-for instance by means of a tommy-bar 50 extending radially from the key 12 - in such a sense as to commence opening the valve, the rising stem 15 will start to rise and thus will lift the detent drive member 13. This action causes the balls 49 to be moved radially outwardly, moving the outermost ball 49 into the annular groove 27 in the shroud. Thereafter, the key 12 is held locked in the shroud 11, because the balls 49 will be held in this disposition by the spacer 46, the head 41, or the rising stem 1 5 itself. Only when the valve has again been fully closed can the balls 49 move radially inwardly, thus freeing the key from the shroud 11.

Though in the illustrated embodiment, there is but one bore 48, it is preferred for there to be at least two such bores, each accommodating balls 49, which bores should then be diametrically opposed. This is to ensure that the outermost ball of at least one of the bores 48 will be engaged in the annular groove 27 when the rising stem 1 5 is in register with the bores 48, notwithstanding the thread-form of the rising stem itself and the possible reception of one innermost ball 49 in a trough in that thread-form. Depending upon the precise type of thread-form, it may be necessary to provide more than two such bores, at appropriate angular dispositions.

The key 12 also has a releasable catch arrangement, serving to prevent the key 1 2 being withdrawn from the shroud 11 even when the channel 45 is aligned with the bore 48, until such time as an operator releases the catch. The catch arrangement comprises a shaft 51 rotatably located in a bore extending parallel to the axis of the key 12, the shaft 51 being held against axial movement by means of a screw-threaded peg 52 extending into a groove formed in the shaft.

Adjacent the lower end of the shaft 51 and in the same radial plane as the bore 48, there is provided a bore 53 in which there is located a ball 54, the outer end of the bore 53 being peened over to prevent the ball 54 moving radially out of the bore.

The free end of the shaft 51 is provided with a cam member 55, which when the illustrated position urges the ball 54 to project from the outer surface of the key. However, on rotating the shaft 51, the cam member 55 allows the ball 54 to move radially inwardly. The upper end of the shaft 51 is provided with a lever 56 for effecting rotation of the shaft 51, and a torsional coil spring 57 is disposed to urge the shaft to such an angular position that the ball 54 is driven radially outwardly by the cam member 55.

It will be appreciated that the lever 56 of the catch arrangement described above must be operated either to fit the key 12 into the shroud 11, or to release the key from the shroud, and when the lever 56 is released once the key has been fitted into the shroud, the shaft 51 will rotate such that the cam member 55 drives the ball 54 radially outwardly into the annular groove 27.

Such a catch arrangement is particularly advangeous when the security device is fitted on a rising stem valve the stem of which projects generally downwardly, because then the key 12 will not fall away from the valve other than when the catch arrangement is operated intentionally.

The annular groove 27 is given a particular cross-sectional profile mentioned above in order that should an attempt be made to remove the key from the shroud other than when the valve is fully closed and the catch arrangement operated, the outermost ball 49 and/or the ball 54 will engage the wall 27a of the annular groove 27 at a point spaced from the junction of the inner circumferential wall of the shroud 11 and the wall 27a of the groove 27. This serves to prevent damage to said junction, which might otherwise occur were the groove to have for example an arcuate profile, the radius of which corresponds to that of the balls.

Claims (13)

1. A security device for a rising stem fluid-flow control valve, which device comprises a turning member adapted to be secured to the nut of the valve and having at least a portion of its external periphery of circular form, there being at least two arcuately-spaced radial projections upstanding from said portion, a shroud adapted to surround with clearance the turning member and provided with means to restrain rotation of the shroud with respect to the valve when fitted thereto, the shroud having an annular groove formed in the inwardly directed surface thereof, an operating key having bore in which may be received the circular portion of the turning member and being adapted partially to fit within the shroud, the key having a plurality of recesses opening into the bore therein which recesses are appropriately positioned to receive the projections on the turning member when the key is fitted into the shroud to engage the turning member, the key also having a through-bore into which the rising stem of the valve may extend, detent means provided in the key and arranged for projection either into the through-bore in the key to such an extent as to lie in the path of the valve stem or beyond the outer periphery of the key for engagement between the key and the shroud, and a detent drive member which has a section able to fit into the throughcore in the, key said section having a first portion of substantially the same diameter as the stem of the valve and a second portion defining an annular channel for receiving the detent means when not projecting beyond the outer periphery of the key, the detent drive member being adjustable to allow pre-setting of the distance between the annular channel of the detent drive member and the end face of said section thereof, the arrangement being such that when the device is fitted to a rising stem valve, said end face of the detent drive member is engaged and moved by the rising stem as the turning member is operated by the key to open the valve from its fully closed setting, thereby moving the detent means to restrain withdrawal of the key from the shroud.

2.A security device as claimed in claim 1, wherein the detent means comprises a member mounted for movement in a radially-extending bore formed in the key to extend from the outer periphery thereof into the through-bore which may accommodate the rising stem, the length of said member being selected having regard to the distance between the outer periphery, of the key and the inner diameter of the through bore, as well as the required projection of the member from the key to be accommodated in the groove in the shroud or in the channel in the detent drive member.

3. A security device as claimed in claim 2, wherein said member comprises a plurality of balls able to roll along the radially-extending bore by a distance not greater than one half of the diameter of one of the balls, and the material of the key at the two ends of the radial bore are deformed slightly so as to prevent the balls leaving the bore.

4. A security device as claimed in any of the preceding claims, wherein there is a plurality of similar detent means equi-spaced around the through-bore in the key, but in substantially the same radial plane.

5. A security device as claimed in any of the preceding claims, wherein the key includes an elongate axial housing which is able to accommodate both the rising stem of the valve and the detent drive member, which latter is disposed for engagement and lifting by the rising stem of the valve.

6. A security device as claimed in claim 5, wherein there is a compression spring disposed between the detent drive member and the end of the housing disposed furthest from the main body of the key.

7. A security device as claimed in any of the preceding claims, wherein the detent drive member comprises a first component in the form of a threaded stub having formed at one end thereof a head adapted to fit within the throughbore in the key and adapted to be engaged by the free end of the rising stem of the valve, and a second component having a screw-threaded bore engaged with the threaded stub of the first component and having a boss which also fits within the through-bore in the key, the boss defining the annular channel of the detent drive member.

8. A security device as claimed in claim 7, wherein a spacer of a pre-determined thickness is positioned and clamped between the head at the end of the first component and the boss of the second component, which spacer has substantially the same diameter as the head so as to prevent erronous operation of the detent means when the detent drive member is lifted by the rising stem to such an extent as the spacer is aligned with the detent means, the thickness of the spacer being such that the detent means is operated when the valve rising stem has reached a pre-set position.

9. A security device as claimed in any of the preceding claims, wherein a releasable catch is provided to retain the key in the shroud, even when the valve is closed, until such time as the catch is released.

10. A security device as claimed in claim 9 wherein the catch includes an element mounted in the key and the spring-urged to a position where the element may engage the groove provided in the shroud, an operating lever being provided to withdraw the element when desired from the groove.

11. A security device for a rising stem fluid flow control valve substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawing.

12. A rising stem valve including a valve body, a nut rotatable with respect to the body and a threaded rising stem interengaged with the nut, in combination with a security device as claimed in any of the preceding claims with the turning member thereof secured to the nut of the valve, and the shroud mounted in a non-rotatable manner on the valve body.

13. A combination as claimed in claim 12, wherein the shroud is indirectly mounted on the body by means of the turning member itself, the shroud being rotatably mounted on the turning member but held against axial movement with respect thereto, and the shroud having an abutment which engages the valve body to prevent rotation of the shroud with respect to the body.