The present invention relates to an actuator for controlling a valve, the actuator incorporating a locking mechanism to enable the valve to be locked in one or more predetermined configurations.

There are many circumstances in which the managers of for example process plant wish to prevent unauthorised actuation of valves. For example, with some processers, if a plant is to be shut down it is vital that valves controlling different parts of the process are closed or opened in a predetermined ordei. A known approach which has been used to ensure such valves are actuated in the appropriate order relies upon individual valve actuators being operable only after insertion of an appropriate key, the key for one valve in a particular series of valves only being accessible to an intended user after actuation of the previous valve in the seπes. For example, if one wishes to control the closing of three valves in the order one. two and three, the person responsible would retain a first key. A second key would be locked into an actuator controlling the first valve, and a third key would be locked into an actuator controlling the second valve. When the user inserts the first key into the first valve actuator, this releases the actuator and enables that valve to be closed. Once the valve has been closed, the second key is released and may be taken to the second valve actuator. Once the second key has been inserted into the second vah e actuator and the associated valve has been closed, the third key is released and may be moved to the third valve actuator to enable the associated valve to be closed. Such an arrangement of keys and actuators makes it impossible for a series of valves to be shut off in an undesired order.

There are many applications were lockable valve actuators would be highly desirable, for example in the offshore petroleum industry. There has been a reluctance to use such actuators however for fear that in a particular emergency situation the first key in a series may be unavailable with a result that none of the valves may be shut off. In a disaster situation it may be evident for example that conditions have already deteriorated to such an extent that it becomes vitally important to shut off say the third

valve in a series even though the first and second valves of that series are inaccessible due to fire.

It is an object of the present invention to provide a valve actuator which may be locked but the locking effect of which may be overridden in an emergency.

According to the present invention, there is provided an actuator for controlling a valve having a valve body and a valve stem the rotation of which relative to the body controls the valve, the actuator comprising a base which in use is engaged with the body of a valve to be controlled such that the base is prevented from rotating relative to the valve body, a drive member which in use is mounted to rotate relative to the base with the stem of the valve to be controlled, a lock mechanism which is engaged with the drive member and is operable to lock the drive member and stem against rotation relative to the base, and means for applying a torque to the drive member and stem to control the valve, wherein the torque applying means is removable, at least one part of the lock mechanism is removable after removal of the torque applying means to thereby disable the lock mechanism, and the torque applying means is engageable with the drive member after removal of the said at least one part of the lock mechanism to enable actuation of the valve.

The torque applying means may be for example a lever which in effect pins the components of the actuator together. Such a lever may be secured in its normal position by a removable component for example a seal, removal of which will be evident subsequently. Thus a locked valve may be released but only by a person prepared to make it apparent that the lock mechanism has been overridden. The lever or other torque applying means could be secured in position by for example a frangible pin or other device displacement of which cannot readily be concealed.

The lock mechanism may comprise a lock body supporting at least one bolt which is displaceable with a key between a first position in which it engages in a recess in the base and a second position in which it enables rotation of the lock body with the drive member relative to the base. The lock body may be received within a casing rotatably supported on the base, the lock body defining a recess within which the drive member is a sliding fit such that the lock body and drive member rotate

together, the torque applying means extending through the casing to engage the lock body, and, after removal of the lock body, to engage the drive member.

The lock mechanism may define a bore through which the torque applying means normally extends, and the drive member may comprise formations between which the torque applying means normally extends.

An embodiment of the present invention will now be described. by way of example, with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of an embodiment of the present invention;

Figure 2 is a further exploded view showing some of the components of Figure 1 and their relationship to a valve spindle;

Figure 3 is an underside view of a component shown in Figure 1 ; and

Figures 4, 5 and 6 illustrate successive stages in the process of removing a lock mechanism from the structure of Figure 1 .

Referring to Figures 1 and 2, the illustrated embodiment of the invention comprises a base 1 , a drive member 2, a lock mechanism casing 3, a lock body 4 and a lever 5. The base 1 defines a central circular bore 6 which receives a tubular extension 7 of the drive member 2. As shown in Figure 2, the drive member 2 defines an axially extending bore the upper end of which defines a rectangular opening 8. That bore receives the spindle 9 of a valve, the end of the spindle being shaped to mate with the rectangular opening 8. The spindle 9 extends from the body of a valve (not shown) to which the base 1 is secured. With the exception of modification made to the shape of the drive member 2 and matching modifications made to the lock body 4 with the drive member 2 is engaged, the illustration componants are identical to componants of a known lockable valve actuator.

As shown in Figure 3, the underside of the lock body 4 defines an opening 10 which receives the portion of the drive member 2 from which the extension 7 projects. That portion of the drive member includes four projections 1 1 one of which is located at each of the four corners of the generally rectangular opening 10. As a result of the inter-engagement between the lock body 4, the drive member 2 and the spindle 9, those three components are constrained to rotate together.

The underside of the lock body 4 defines a track 12 in which a ball bearing 13 supported on the base 1 runs. The underside of the lock body 4 also supports a pair of ball bearings 14 which in turn run in a track 15 provided on the base. As a result of the inter-engagement between the balls and tracks, and in particular the provision of sockets at the end of each of the tracks into which the balls which are spring loaded drop when appropriately aligned, a user can readily feel when the lock body 4 has been rotated to one of the positions in which the balls and sockets engage. These positions are offset relative to each other by 90 about the spindle axis. When the lock body 4 and base 1 are appropriately positioned, the two components can be locked against relative rotation by bolts 16 and 17 (Figure 1 ) supported in the lock body 4. The bolts 16 and 17 are cylindrical in shape and are rotatable relative to the lock body 4 about the cylinder axis. Lower portions of the bolts define cutouts such that in one orientation the remaining portion of the lowermost part of the bolt can be received in recesses 18 and 19 formed in the base and in an alternative configuration can move freely part the recesses 18 and 19.

The positions of the bolts 16 and 17 relative to the cylindrical bores in the lock body 4 in which they are received can be controlled by keys. In the illustrated structure, a blanking plate 20 positioned over the bore which receives the bolt 17 isolates that bolt from any user intervention. Accordingly the bolt 17 will always be in a position in which it can move past the recess 17. The other bolt 16 however can be rotated by means of a key 21 which may be inserted into the lock body through the protective cover 22 having a pivotably mounted lid and a lock barrel 23. The key 21 thus enables the bolt 16 to be engaged in the recess 18 to lock the valve in one configuration or to be engaged in the recess 19 to lock the valve in an alternative configuration. If the valve was to be used in a situation where a key was captive and could only be removed after appropriate positioning of the associated valve, a similar key would be provided to control the position of the bolt 17. the key being removable only after a rotation of the bolt 17 which would only be possible if the bolt 17 was adjacent to the recess 19. This arrangement of captive keys is entirely conventional and will not therefore be described further.

The base 1 is secured to the valve body and the drive member 2 is secured to the valve spindle. The casing 3 is rotatably supported by the base 1, separation of the casing 3 from the base 1 being prevented by three screws 24 the radially inner ends of which are engaged in a circumferential slot 25 in the base 1 The lock body 4 is pinned to the casing 3 by the lever 5 which extends through a radial opening 26 in the casing 3, a bore 27 in the lock body 4, and a further radial opening 28 in the casing 3. Two circlips 29 and 30 are received in respective circumferential grooves in the lever 5, the circlip 30 being located immediately outside the casing 3 adjacent the opening 28 and the circlip 29 being located immediately outside the casing 3 adjacent the opening 26. The lever extends between the projections 1 1 defined by the drive member 2. The application of a force to the lever 5 applies a torque to the assembly made up of casing 3, lock body 4 and drive member 2 and that torque is delivered to the valve spindle 9 as a result of the inter-engagement between that spindle and the drive member 2.

In normal operation, the lever 5 will never be removed from the assembly. In order to ensure that the lever is not removed in an unauthorised manner, the circlip may be covered by a seal such that once the circlip 30 has been removed it cannot be replaced without its earlier removal being evident. For example the circlip 30 could be covered in a sealing compound. Alternatively the circlip could be replaced by a frangible member which could only be removed by being broken. Of course there will be many ways in which the lever 5 can be releasably retained against removal from the assembly in a manner such that if the lever is removed its removal is subsequently evident.

In normal operation, the lever is retained in position and the valve is always left in a locked condition. Accordingly the valve can only be actuated by a person in possession of the key 21. If however in an emergency it becomes imperative to actuate the valve in circumstances when the key is not available, the circlip 30 is removed, for example by striking the adjacent end of the lever 5 with a hammer so that the circlip is dislodged, the lever 5 is pulled out of the assembly (sec Figure 4), the lock body 4 is lifted out of the casing, this being possible given that in the absence

of the lever 5 there is no direct inter-engagement between the lock body 4 and either the casing 3 or the drive member 2, the lever 5 is reinserted though the openings in the casing 3 (Figure 5), the reinserted lever extending between the projections 1 1 defined by the drive member 2 (see Figure 6). and the valve can then be actuated by simply applying an appropriate force to the lever 5. Thus the illustrated structure enables the locking mechanism to be removed completely from the assembly in an emergency but such removal will be evident assuming that an appropriate sealing structure is provided to indicate removal of the circlip 30. Of course, alternatives to the circlip may be provided, for example a pin or other elongate member extending through a radial hole in the lever and secured against accidental removal by a tag or other breakable sealing device.

It will be appreciated that the casing 3 and lock body 4 could be a single component, providing the drive member is appropriately shaped so as to be engagable by the lever 5 after removal of the combined casing and lock mechanism. For example, the drive member could be provided with loop formations through which the lever would extend rather than spaced apart pairs of projections 1 1 as in the illustrated arrangement.