GB2237620A - Valve test device - Google Patents

Abstract

A valve test device enables a valve installed in a pipeline to be tested in situ by allowing a limited degree of rotation of the valve stem without disrupting flow in the pipeline. The device has a housing for mounting on the valve, and a drive member (22) rotatable within the housing for interposition between the valve and its actuator. The member (22) has a pair of flats (40, 42) which cooperate with a locking pin (18, 60) to allow restricted rotation of the member (22) during testing. Free rotation of the drive member (and valve) may be restored by removal of the locking pin (18) or by rotation of the pin (60) to a position clear of the member (22). Rotation of the pin (60) may be effected manually or by means of a piston and cylinder through a rack and pinion mechanism. <IMAGE>

Description

VALVE TEST DEVICE The present invention relates to a device for in situ testing of valves having a rotatable valve stem, particularly those installed in pipelines.

Valves having a rotatable valve stem, particularly butterfly valves, are commonly used to shut off or restrict the flow of fluids in pipelines. In many instances, a valve will be used for prolonged periods in the same position, for example the open or shut position, so that there is a danger of the valve becoming seized up. For this reason, it is desirable to test valves periodically by opening and closing them. However, in order to test a valve in situ, it is usually necessary to shut down the associated plant. This is costly in terms of lost production time.

It is therefore an object of the present invention to provide a simple device which allows valve operability to be verified without the need to close off the pipeline.

The present invention provides a valve test device for allowing restricted rotation of a valve stem during testing thereof, which comprises - a housing for mounting on a valve body, a passage to accept a locking member and a bore passing through the housing; - a spool rotatably located within the bore and having valve connection means for connecting the spool to said valve stem, and having actuator connection means for connecting the spool to valve. actuator means, whereby the spool transmits rotational movement from the actuator means to the valve stem; and rotational stop means provided on the spool; - the arrangement being such that when the locking member is moved along the passage into an engaged position, wherein the locking member co-operates with the stop means, rotational movement of the spool is restricted so as to enable testing to be carried out.

Usually the housing includes mounting means for mounting the housing on a valve body. Alternatively, the housing might be integrally formed with the valve body.

The housing generally also has on an opposite face thereof further mounting means for allowing an actuator to be mounted onto the housing. Usually, each mounting means is simply a flange provided with bolt holes or other mounting means known in the art.

The present invention also extends to the combination of the locking member with the valve test device.

Generally, the locking member is in the form of a pin which intrudes into the bore in the spool so as to co-operate with the rotational stop means. The pin is usually cylindrical, but any suitable elongate member may be employed. In order to locate the pin correctly within the passage for proper co-operation with the rotational stop means, it is preferred to provide positive location means on the pin, for example in the form of a bayonnet-type coupling between the pin and the housing.

The spool is rotatably located within the bore and is provided with rotational stop means for co-operation with the locking member. The stop means are usually in the form of flats recessed below the cylindrical surface of the spool and these determine the allowable rotation of the valve stem. The stop means are usually arranged to allow a rotational angle of 10 -400 (usually 15 to 250) either side of a centre position, so as to allow the test device to be used for fail-safe clockwise or anti-clockwise rotation of the valve. Usually, the test device is used in conjunction with valves which are normally in the open position, so that the restricted rotation allowed by the test device does not significantly affect the flow through the pipeline.If required, the spool may have multiple sets of stop means arranged around it to allow for restricted rotation of the valve when the valve is in any one of a number of positions between fully closed and fully open.

The test device is intended to be interposed between the valve and the usual actuator means and as such appropriate male and female connection means are provided.

The term "actuator means" is intended to cover both automatic (e.g. electrically or pneumatically operated) and manual actuators (e.g. handwheels).

In one preferred form of the invention, the locking pin is inserted manually into the test device. However, in a further embodiment, the locking pin is an integral part of the test device and is provided with remotely operable means (e.g. electrically or pneumatically operated) for moving the locking member into the engaged position. Preferably, resilient biasing means are provided to withdraw the locking pin to the fail-safe withdrawn position. Sensors (e.g. mechanical switches or proximity switches) may then be provided to ensure that the pin is correctly introduced along the passage, that the spool correctly rotates through the allowed rotational angle, and that the pin has finally been fully retracted.

The information concerning a successful test sequence may then be fed back to a computerised control centre.

In another form of the invention, the locking member is non-removable from the housing, and is rotatable from an engaged to a non-engaged position. In one rotational position the locking member co-operates with the stop means to restrict rotation of the spool, whilst rotation of the locking member (for example, through 90 ) brings a cutout in the locking member adjacent the stop means and allows unrestricted rotation of the spool.

Preferably, an interlock is provided to prevent unauthorised operation of the locking member.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings wherein Figure 1 is a plan view of a first embodiment having a removable locking pin; Figure 2 is a side elevation thereof; Figure 3 is a view from beneath; Figure 4 is a section through X-X of Figure 1; Figure 5 is a section along Y-Y of Figure 2; Figure 6 is a view of a blanking plug; Figure 7 is a part-sectioned plan of a second embodiment having an integral rotatable locking pin; and Figure 8 is a front elevation thereof.

The valve test device shown in the drawings comprises a housing 2 having an upper flange 4 provided with bolt holes 6 etc. for connection to a valve actuator and a lower flange 8 provided with screwed bores 10 etc. for connection to a valve body. The housing has a passage 12 which accepts a locking pin 14 having a T-bar 16 at one end. The other end 18 of the pin intrudes into a central bore 20 through the housing. The bore is cylindrical and accommodates a rotatable spool 22 comprising an outer shell 24 and an inner shell 26 of harder material. Nylon bushes 28, 30 are provided between the housing and the spool. The spool has a central substantially oval bore 32 therethrough to accept a shank 34 of corresponding cross-section fitted with a circlip 36 for location purposes.The shank is removable and may be fitted into either end of the bore 32 according to the particular valve/actuator arrangement.

As shown in Figure 5, the spool 22 includes two flats 40,42 arranged at about 200 either side of a central position, and which act as rotational stops when the pin is in the engaged position.

Figure 6 shows a blanking plug 50 having a locating pin 52 protruding therefrom for co-operation with a corresponding bayonnet recess in the housing to enable the blanking plug to be located in position. A rubber ring 56 fits around the blanking plug for sealing the passageway in the housing against ingress of dirt. A similar locating pin 54 is provided on locking pin 14.

The valve test device may be operated as follows.

First, the actuator is removed from the valve body and the valve test device is bolted in between, with the valve stem protruding into the lower end of oval bore 32 and shank 34 extending into the actuator. In this way, the actuator is able to operate the valve in the normal way.

In order to test the operation of the valve, pin 14 is introduced into passageway 12 and turned one quarter of a turn so that locating pin 54 engages the corresponding bayonnet fitting so as to position the end 18 of the pin in the correct position in relation to flaps 40,42 on-the spool. This restricts rotational movement of the spool to about 200 either side of the centre position. The arrangement of the flats is such as to exert substantially no net force pushing the pin out of the passageway. The valve actuator may now be operated to test the valve.

However, only restricted movement of the valve spool is permitted until flap 40 or 42 engages the end 18 of the pin. In this way, complete closure or opening of the valve is avoided so that flow along the pipeline is substantially unaffected. After testing the pin 14 is turned back a quarter of a turn and withdrawn, and blanking plug 50 is fitted.

Figures 7 and 8 show a second embodiment which is generally similar to the first embodiment; except that the locking pin 60 is permanently installed and is not removable and is rotatable about its longitudinal axis from a locked to an unlocked position. An interlocking device 70 (usually key operated) is also provided to prevent unauthorised use.

Locking pin 60 is slightly wider than in the previous embodiment and is non-retractably located in the passage in the housing by means of a grub screw (not shown) screwed into the base of the housing and protruding into a slot 62 in the stem of the locking pin. The length of the slot 62 allows for rotation of the locking pin through about 90". A handle 64 is located at the free end of the locking pin to facilitate manual rotation. The free end is also provided with a flat 66 for engagement with a retractable bolt 72 of the interlocking device 70. The locking pin which is generally of cylindrical shape also includes a further flat portion 68 recessed below the cylindrical surface, such that when the locking pin is as shown in the drawing there is no obstruction to full rotation of the valve spool 22.However, when the locking pin is turned through 90% it adopts the position shown in the dotted line, thus allowing only limited rotation of the valve spool 22 for test purposes.

Interlocking device 70 is usually key operated to allow operation of knob 70, which causes the bolt 72 to be thrown into a locking position abutting the flat 66 of the locking pin or causes the bolt to be retracted. Any suitable interlocking device may be employed.

The second embodiment may be operated as follows.

First, the interlocking device is unlocked and knob 70 is turned to retracted bolt 72 and allow rotation of the locking pin. Then the locking pin is rotated through 90 using handle 64 so as to adopt the position shown by the dotted line in Figure 7. In this position only limited rotation of valve spool 22 is permitted thereby allowing operation of the valve to be tested. After testing, the locking pin is rotated back again so that the spool is free to rotate through cutout 68 once again. The key may then be withdrawn from the interlock. In this embodiment there is no danger of the locking pin being lost, or of operation by unauthorised personnel.

Moreover, the profile of the locking pin means that the bolt cannot be extended (and the key removed from the interlock) unless the locking pin is rotated to the unlocked position. Thus, the key cannot be removed from the interlock when the test device is in the test mode.

This helps prevent the valve being accidently set to or left in the test position.

In a modification, the second embodiment can be arranged for automatic operation. In this case the locking pin 60 carries a pinion in place of handle 64, which engages a longitudinally reciprocatable rack operated by a pneumatic or hydraulic cylinder. In order to sense whether the locking pin has been correctly rotated, the locking pin is extended through the housing and is provided with proximity switches thereon which sense the rotational position of the locking pin. Spring biasing means may be provided to return the locking pin from the test position to provide fail-safe protection.

Claims (10)

1. A valve test device for allowing restricted rotation of a valve stem during testing thereof, which comprises; - a housing for mounting on a valve body, a passage to accept a locking member and a bore passing through the housing; - a spool rotatably located within the bore and having valve connection means for connecting the spool to said valve stem, and having actuator connection means for connecting the spool to valve actuator means, whereby the spool transmits rotational movement from the actuator means to the valve stem; and rotational stop means provided on the spool; -the arrangement being such that when the locking member is located in the passage in an engaged position, wherein the locking member co-operates with the stop means, rotational movement of the spool is restricted so as to enable testing to be carried out.

2. A device according to claim 1 wherein the rotational stop means comprise flats recessed below the cylindrical surface of the spool.

3. A device according to either preceding claims wherein the stop means allow a limited rotation of the spool of 15 to 25 either side of a centre position.

4. A device according to any preceding claim which comprises multiple stop means to allow for restricted rotation about a number of positions of the valve.

5. A device according to any preceding claim which further comprises a removable locking member, which when located in the passage co-operates with the stop means to restrict rotational movement of the spool.

6. A device according to claim 2 which further comprises a bayonet coupling between the locking member and the housing for positively locating the locking member in position in the passage.

7. A device according to claim 5 or 6 which further comprises remotely operable means for moving the locking member along the passage into the engaged position.

8. A device according to any of claims 1 to 4 which comprises a rotatable locking member having a cutout portion adjacent the spool stop means, whereby in one rotational position the locking member co-operates with the stop means to restrict rotation of the spool, and in another rotational position the cutout clears the stop means so that unrestricted rotation of the spool may occur.

9. A device according to claim 8, which further comprises an interlock to prevent unauthorised operation, the interlock comprising a retractable bolt which in a locked position engages a flat provided on the locking member so as to prevent rotation of the locking member.

10. A valve test device substantially as described in conjunction with Figures 1 - 6 or Figures 7 and 8.