The present invention relates to the fields of valves and manually operable valves, for instance gate valves, control or regulation valves or chokes valves. More particularly, the invention relates to a valve operator assembly for a gate valve.

Valves are used in a variety o f industries to control the flow o f fluids. In particular, gate valves are used extensively in the oil and gas industry to control the flow o f produced fluids at various stages o f production. Most gate valves used in this industry comprise a valve body having a longitudinal flow bore and a transverse gate cavity that intersects the flow bore. A gate having a gate opening extending transversely therethrough is disposed in the gate cavity. A valve stem is provided for moving the gate between an open position, in which the gate opening is aligned with the flow bore, and a clo sed position, in which the gate opening is offset from the flow bore . The gate cavity o f the valve body is covered by a bonnet having an axial bore transverse to the flow through which passes the valve stem.

Such a gate valve is associated to a valve operator assembly for selectively driving the valve stem up and down in order to close and open the gate valve . The valve operator assembly generally comprises a transmission mechanism to convert the rotational motion o f a drive input into axial motion of the valve stem. To quickly open and close the gate valve with a minimum number of turns, the transmission mechanism may be a ball screw mechanism or a planetary roller screw mechanism in order to reduce the operating torque, for instance manual hand-wheel torque or powered with electric, hydraulic or pneumatic drive for surface valves or with remote operating vehicle (ROV) torque tool or electric or hydraulic actuation for subsea valves. For more details, it is possible for example to refer to the patent EP- B l - 1 419 334 (SKF) .

When operating a gate valve, the force to apply to the valve stem is maximum at the beginning of the valve opening and also at the end o f the valve clo sing. Then the force to apply is less important and substantially constant. Accordingly, the required torque on the rotational drive input, such as a manual hand-wheel, is usually much higher at the start of the valve opening and at the end of the valve closing.

One aim o f the present invention is to overcome this drawback. It is a particular object of the present invention to provide a valve operator assembly for valve, for instance gate valve, control or regulation valve or choke valve, wherein the required torque for opening and closing said valve is limited.

It is also a particular obj ect of the present invention to provide a valve operator assembly adapted to open and clo se faster the valve with a compact and simp le design.

In one embodiment, the valve operator assembly is provided for a valve comprising a valve body and a valve translating member axially moveable. The assembly comprises a housing adapted to be mounted on the valve, an input member rotatably mounted with respect to said housing, and a transmission mechanism comprising a translating element adapted to be connected to the valve translating member of the valve and provided with a thread, and a rotating element connected to the input member and provided with a thread. Said transmission mechanism is adapted to convert applied rotation o f the input member into axial translation of said translating element.

The assembly further comprises at least one guide means provided on the translating element o f the transmission mechanism and protruding radially outwards with respect to said translating element, and at least one guide member provided on the housing and cooperating with said guide means. The guide member comprises at least one anti-rotation portion extending substantially axially so as to guide axial movements o f the translating element and to prevent angular movement of said translating element relative to the housing, and at least one guide portion connected to said anti-rotation portion and extending both axially and circumferentially so as to guide combined axial and angular movements of the translating element relative to the housing.

In one preferred embodiment, the anti-rotation portion extends purely axially to form a straight portion.

In one embodiment, the guide member comprises facing guide surfaces extending parallel with each other and in contact with the guide means.

In one embodiment, the anti-rotation portion of the guide member is axially located on the side of the rotating element of the transmission mechanism with regard to the guide portion.

Alternatively, the guide portion may be axially lo cated on the side o f the rotating element with regard to the anti-rotation portion.

Advantageously, the translating element is adapted to be rotatably connected to the valve translating member of the valve.

The guide portion of the guide member may extend circumferentially in a direction identical to the thread direction o f the translating element. Alternatively, said guide portion may extend circumferentially in a direction opposite to the thread direction o f the translating element. The guide portion may have a helicoidal form.

In one embodiment, the guide member comprises at least one groove within which engage said guide means and delimiting the anti- rotation portion and the guide portion. The groove may be formed in the thickness of the housing. In another embodiment, the guide member is attached to the housing.

In one embo diment, said guide means comprise a rolling means connected with the translating element and rotatable about an axis lo cated at a fixed position on said translating element, said rolling means comprising an outer surface rollable along the anti-rotation portion and the guide portion.

The transmission mechanism may comprise a screw provided with an outer thread and a nut surrounding and coaxial with said screw, said nut being provided with an inner thread. In this case, the screw forms the translating element and the nut forms the rotating element, or vice versa. The invention also relates to a valve comprising a valve body, a valve translating member axially moveable and a valve operator assembly as previously defined.

The present invention and its advantages will be better understood by studying the detailed description o f specific embodiments given by way o f non-limiting examp les and illustrated by the appended drawings on which:

Figure 1 is a cross-section o f a valve operator assembly for gate valve according to a first examp le o f the invention,

- Figures 2 and 3 are detail views o f Figure 1 ,

Figure 4 is a section on IV-IV of Figure 1 ,

Figure 5 is a cross-section of a housing of the assembly o f

Figure 1 ,

Figure 6 is a cross-section o f a valve operator assembly according to a second example of the invention, and

Figure 7 is a cross-section o f a valve operator assembly according to a third example of the invention.

A valve operator assembly 10 as shown on Figure 1 is adapted for a gate valve 12 provided with a bonnet 14, a valve body (not shown) covered by said bonnet and a moveable valve stem 16 with an axis 16a. Conventionally, the valve bo dy has a flow bore and a transverse gate cavity that intersects the flow bore. The gate valve also comprises a gate having a gate opening extending transverse ly therethrough is disposed in the gate cavity. For more detail on such a gate valve, it could be referred to EP-B l - 1 419 334 (SKF) .

The valve operator assembly 10 comprises a tubular housing 1 8 mounted on the bonnet 14 of the gate valve, an input member 20 rotatably mounted with respect to said housing, and an inverted roller screw mechanism 22 interposed between said input member and the valve stem 16 of said valve to convert a rotational motion o f the input member 20 into axial motion of the valve stem. The inverted roller screw mechanism 22 is mounted into a bore 1 8a of the housing and is connected to the input member 20. One axial end of the housing 1 8 is secured to the bonnet 14 by threads or bolts. In the illustrated example, the bore 1 8a has a stepped form. Alternatively, the bore 1 8a may have different shape.

As shown more clearly on Figure 2, the mechanism 22 comprises a screw 24, with an axis 24a coaxial with the axis of the valve stem, provided with an outer thread 26, a nut 28 mounted coaxially about the screw 24 and provided with an inner thread 30, the internal diameter of which is greater than the external diameter of the outer thread 26, and a plurality o f longitudinal rollers 32 arranged radially between the screw 24 and the nut 28. The screw 24 extends longitudinally through a cylindrical bore of the nut 28 on which the inner thread 30 is formed. The lead o f the outer thread 26 of the screw is constant. The nut 28 has a tubular form and is elongated to accommo date the full extent of screw travel.

The ro llers 32 are identical to each other and are distributed regularly around the screw 24. Each roller 32 extends along an axis 32a which is coaxial with the axis 24a o f the screw and comprises an outer thread 34 engaging the thread 26 o f the screw and the thread 30 of the nut. Each roller 32 also comprises, at each axial end, outer gear teeth 36, 38 extending axially outwards the outer thread 34 and which are themselves extended axially by a cylindrical stud 40, 42 extending outwards. Each gear teeth 36, 38 are axially located between the associated stud 40, 42 and the outer thread 34. The outer thread 34 o f each ro ller is axially lo cated between the two gears 36, 38.

The ro ller screw mechanism 22 also comprises two annular gear wheels 44, 46 provided on the outer surface o f the screw 24 and each comprising outer gear teeth meshing the gear teeth 36, 38 respectively o f the ro llers 32 for the synchronization thereof. Each gear wheel 44, 46 is axially located near to an end of the outer thread 26 of the screw. Said outer thread 26 is axially located between the two gear wheels 44, 46. In the disclo sed embodiment, the gear wheels 44, 46 are formed directly on the outer surface of the screw 24. Alternatively, the gear wheels may be separate parts which are fixed onto the screw 24. The mechanism 22 further comprises two annular guides or spacer rings 48 , 50 disposed on the outer surface of the screw 24. Said spacer rings 48 , 50 are radially disposed between the screw 24 and the inner thread 30 of the nut without contact with said thread. Each spacer ring 48 , 50 is mounted on the outer surface of the screw 24 axially next to the associated gear wheel 44, 46. Each spacer ring 48 , 50 is axially offset towards the outside of the nut 28 with regard to the associated gear wheel 44, 46. Each spacer ring 48 , 50 comprises a plurality o f cylindrical through-recesses (not referenced) which are distributed regularly in the circumferential direction and inside which the studs 40, 42 o f the rollers are housed. The spacer rings 48 , 50 enable the rollers 32 to be carried and the regular circumferential spacing thereo f to be kept. The mechanism 22 further comprises elastic retainer rings 52, 54 each mounted in a groove (not referenced) formed on the outer surface of the screw 24 in order to axially ho ld the corresponding spacer ring 48 , 50.

Referring once again to Figure 1 , as will be described later, the valve operator assembly 10 further comprises guide means 56 connected to the screw and cooperating with a groove 58 provided on the housing 1 8 in order to decrease during the opening and the clo sing of the gate valve 12 the required torque on the input member 20 and to increase the operating speed.

The valve operator assembly 1 0 also comprises rolling bearings 66 to 68 to guide the rotation of the nut 28 of the inverted roller screw mechanism. The rolling bearings 66 to 68 are radially mounted between the outer surface of the nut 28 and the stepped bore 1 8a of the housing. The rolling bearings 66 to 68 are mounted radially in contact with the outer surface o f the nut 28 and a large diameter portion of the stepped bore 1 8a of the housing. In the disclo sed examp le, the ro lling bearings 66 to 68 are angular contact thrust ball bearings and are disposed axially in contact one to another. A retaining ring 69 is secured on the outer surface of the nut 28 and axially bears against the rolling bearing 66. Axially on the opposite side, the rolling bearing 68 is axially mounted against a flange (not referenced) o f the nut 28 extending radially outwards the outer surface o f said nut. The flange is axially located at an axial end of the nut.

The input member 20 comprises an adapter sleeve 74 mounted on the nut 28 and an operable hand-wheel 76 secured to said sleeve . The hand-wheel 76 forms a rotational drive input. The sleeve 74 comprises an annular axial portion 74a secured to the flange of the nut by any appropriate means, for example by threads, a radial portion 74b extending radially inwards said axial portion 74a, and a pin 74c proj ecting axially outwards from said radial portion 74b and onto which is secured the hand-wheel 76. The axial portion 74a bears axially against the end of the nut 28. Sealing means (not referenced) are provided between the axial portion 74a of the sleeve and the bore of the housing 1 8.

As shown more clearly on Figures 3 and 4, the guide means 56 are secured to the screw 24. The guide means 56 radially protrude outwards with respect to the outer surface of the screw 24. The guide means 56 are located at a fixed position on the screw 24. As will be described later, the guide means 56 are rollable along the groove 58 provided on the housing 1 8.

The guide means 56 comprise a pin 60 connected with the screw 24 and a ro ller 62 rotatably coupled with the pin. The roller 62 may be maintained on the pin 60 by a screw (not shown) . In the illustrated example, the guide means 56 further comprise a sleeve 64 radially surrounding the part of the pin 60 which protrudes outwards. The sleeve 64 radially bears against the outer surface of the screw 24.

The pin 60 is connected to the screw 24. The pin 60 radially protrudes outwards with respect to the outer surface of the screw 24. The pin 60 comprises an inner mounting portion (not referenced) mounted into a hole 24b o f the screw and an outer mounting portion (not referenced) onto which is rotatably mounted the roller 62. In the illustrated example, the inner mounting portion of the pin 60 comprises an external thread cooperating with an internal thread of the ho le 24b to secure the guide means 56 onto the screw 24. Alternatively, the pin 50 may be secured to the nut 16 by any other appropriate means, for instance by press-fitting, gluing, or welding, etc. The ho le 24b extends radially from the outer surface of the screw.

The ro ller 62 is radially spaced apart from the screw 24. The roller 62 is mounted into the groove 58 provided on the housing 1 8 and is rollable along said groove. The roller 62 engages within the groove 58. The roller 62 is rotatable about an axis 62a located at a fixed position on the screw 24. The axis 62a is perpendicular to the axis 24a of the screw. With regard to the axis 24a, the axis 62a extends radially. The roller 62 comprises an outer rolling surface 62b . In the illustrated example, the rolling surface 62b has a cylindrical form. In another embodiment, the rolling surface may have a profile with curvatures or be a combination o f several surfaces.

As shown more clearly on Figure 5 , the groove 58 is formed on the bore 1 8a o f the housing. The groove 58 is formed radially towards the outside from the bore 1 8a. The groove 58 is made into the thickness o f the housing 1 8. The groove 58 is formed on a limited length of the bore 1 8 a. The groove 58 is axially lo cated on the housing 1 8 between the nut 28 of the screw mechanism and the end o f the screw 24 connected to the valve stem 16 (Figure 1 ) .

As shown on Figures 3 to 5 , the groove 58 is delimited by two guide surfaces 58a, 58b facing each other. The guide surfaces 58 a, 58b extend parallel to each other. The roller 62 of the guide means is disposed between the guide surfaces 58 a, 58b of the groove . The guide surfaces 58a, 58b form guideways for the roller 62. The roller 62 rolls along the guide surfaces 58a, 58b of the groove and comes into contact with said surfaces . The spacing distance between the surfaces 58 a, 58b is slightly greater than the diameter of the roller 62 at least at the contact position.

The groove 58 comprises a straight anti-rotation portion 70 extending parallel to the axis 24a o f the screw and a curved guide portion 72 extending both axially and circumferentially on the housing. The anti-rotation portion 70 is distinct from the guide portion 72. The straight portion 70 extends purely axially with regard to the axis 24a. The straight portion 70 is axially located on the side o f the nut 28 (Figure 1 ) o f the screw mechanism with regard to the guide portion 72.

The guide portion 72 is connected to an end of the straight portion 70 which is axially opposed to the nut 28. The guide portion 72 extends said end of the straight portion 70. The guide portion 72 extends both axially and circumferentially with regard to the axis 24a. In the disclo sed example, the guide portion 72 extends helicoidally. Alternatively, the guide portion 72 may also have different shape. Along the guide portion 72 o f the groove the guide surfaces 58 a, 58b extend both axially and circumferentially on the housing 1 8. Along the straight portion 70 of the groove the guide surfaces 58a, 58b extend axially on the housing 1 8 , i. e. parallel with the axis 24a of the screw.

Referring once again to Figure 1 , axially on the side opposite to the input member 20, a recess 24c is formed on a frontal radial surface o f the screw 12 and into which is mounted an end o f the valve stem 1 6 o f the gate valve. The screw 24 is rotatably connected to the valve stem 16. The screw 24 is axially moveable together with the valve stem 16 and rotatable relative to said valve stem. To this end, rolling bearings and thrust rings (not referenced) are mounted into the recess 24c o f the screw radially between said screw and the valve stem.

When an operator applies a torque on the hand-wheel 76, this torque is transmitted to the nut 28 of the inverted roller screw mechanism. With the rotation of the nut 28 , the rollers 32 rotate on themselves about the screw 24 and move axially and additionally rotate in the nut 28. The rollers 32 are rotationally guided by outer gear wheels 44, 46 provided on the screw and meshing with the gear teeth of the rollers. Both the rollers 32 and the screw 12 are axially or longitudinally moveable into the nut 28. Accordingly, the rotational motion o f a hand-wheel 76 is converted into a displacement of the screw 24.

If the guide means 56 secured to the screw 24 are engaged within the straight portion 70 o f the groove of the housing as shown on Figure 1 , the rotation o f the nut 28 is converted into a linear translation of the screw 24. Said linear guidance of the screw 24 is done along its axis 24a. The screw 24 only has an axial movement relative to the nut 28 and the housing 1 8. An angular movement of the screw 24 is prevented by the cooperation of the guide means 56 with the straight portion 70 of the groove . The roller 62 of the guide means rolls along the guide surfaces 58 a, 58b of the straight portion 70. The straight portion 70 of the groove forms anti-rotation means for the screw 24 cooperating with associate anti-rotation means formed by the guide means 56. The valve stem 16 of the valve gate is axially moved together with the screw 24.

When the roller 62 of the guide means reaches the guide portion 72 of the groove, the rotational motion of the hand-wheel 76 is converted into combined movements of translation along the axis 24a and rotation around said axis o f the screw 24 relative to the nut 28 and the housing 1 8. The screw 24 moves simultaneously both in the axial and circumferential directions.

As a matter of fact, with the guide means 56 secured to the screw 24 and engaging into the guide portion 72 o f the groove of the housing, said screw is forced to rotate relative to the housing 22. The roller 62 of the guide means rolls along the guide surfaces 56a, 58b o f the guide portion 72 o f the groove.

With the cooperation between the guide means 56 and the guide portion 72 of the groove, the rotation of the nut 28 is converted into an axial translation combined with an angular movement of the screw 24 with respect to the housing 1 8. The screw 24 moves simultaneously both in the axial and circumferential directions. The guide portion 72 of the groove guides the combined axial and angular movements o f the screw 24 relative to the housing 1 8. An angular displacement of the screw 24 relative to the guide member 22 and to the nut 28 is forced when said nut rotates .

The resulting displacement of the screw 24 is the combination of two movements, i. e. the one generated by the lead of said screw under rotation and the other generated by the design of the guide portion 72 of the groove. The screw 24 is axially moveable simultaneously in the axial and circumferential directions with regard to the housing 1 8. The guide portion 72 forms a guiding path for the guide means 56 and enables to obtain, during rotation of the nut 28 , a translation movement of the screw 24 combined to a rotation movement with regard to said nut and the housing 1 8. The valve stem 1 6 of the valve gate is axially moved together with the screw 24. The rotation of the screw 24 is not transmitted to the valve stem 1 6.

With the provision of the guide means 56 on the screw 24 cooperating with the guide portion 72 of the groove of the housing, the resulting axial displacement of the screw 24 per turn of the nut 28 is not equal to the lead of said screw. If the thread 26 o f the screw is a right-hand thread and if the guide portion 72 has also a right-hand angle direction as shown on the Figures, the axial travel o f the screw 24 per turn of the nut 28 is higher than the lead o f said screw. Therefore, the value of the axial displacement of the screw 24 per turn of the nut 28 results from the lead o f the screw and the design of the guide portion 72 of the groove. The value o f this resulting axial displacement per turn may be easily adjusted at the desired length with a modification o f the guide portion 72 of the housing 1 8.

Under a constant torque applied to the input member 20, the valve operator assembly 10 has a variable lead. A first lead is obtained when the guide means 56 are engaged within the straight portion 70 o f the groove of the housing and a second lead with higher value is obtained when the guide means 56 are engaged within the guide portion 72 of said groove . The lead o f the assembly 10 varies along the displacement of the guide means 56 into the groove o f the housing 1 8.

Accordingly, the groove 58 and the guide means 56 are advantageously provided respectively on the housing 1 8 and on the screw 24 in such a way that, when operating the gate valve 12, the guide means 56 are lo cated into the straight portion 70 of the groove at the beginning of the valve opening and at the end o f the valve clo sing, and said guide means 56 are located into the guide portion 72 during the other operating runs . In this case, the valve is opened and closed faster. The number o f turns required to travel the stroke to open or close is minimized while keeping a low operating torque.

In the second example illustrated on Figure 6 , in which identical parts are given identical references, the valve operator assembly 10 differs in that it comprises a ball screw mechanism 80. The screw mechanism comprises a nut 82 mounted coaxially about the screw 24 and provided with an inner thread, and a plurality o f identical balls 84 disposed radially between the screw 24 and the nut 82 and which engage the thread of said nut and the thread 86 of the screw. The nut 82 comprises recirculating means 88 , 90 mounted into its thickness to achieve the recirculation of the balls 84. Such screw mechanism is called a standard ball screw. Alternatively, recirculating means may be provided on the screw. Such mechanism is called an inverted ball screw.

In this examp le, the screw mechanism 80 also comprises an outer sleeve 92 having an axial bore 92a having a stepped form and inside which is housed the nut 82. The nut 82 is mounted into the bore 92a o f the outer sleeve and axially bears against a radial annular shoulder of said bore . Axially on the opposite side, a retaining ring 94 is secured into the bore 92a of the outer sleeve and axially comes into contact against the nut 82. The nut 82 is secured to the outer sleeve 92. The nut 82 and the sleeve 92 form together a rotating element.

The ro lling bearings 66 to 68 are mounted on the outer surface of the sleeve 92. The sleeve 92 is radially interposed between the nut 82 and the rolling bearings 66 to 68. The rolling bearing 68 is axially mounted against a flange 92b o f the sleeve extending radially outwards the outer surface of said sleeve. The flange 92b is axially lo cated at an axial end o f the sleeve. In this example, the adapter sleeve 74 o f the input member is secured to the flange 92b o f the outer sleeve and axially bears against said flange. Alternatively, it could be possible to make the nut 82 and the sleeve 92 in one single part. In this case, the rolling bearings 66 to 68 are mounted directly on the outer surface o f the nut. The third example illustrated on Figure 7, in which identical parts are given identical references, differs from the previous embodiment in that the screw 24 has an increased lead and in that the disposition o f the straight anti-rotation portion 70 and the guide portion 72 on the housing 1 8 is inverted. The guide portion 72 is axially lo cated on the side of the nut 28 of the screw mechanism with regard to the straight portion 70. The straight portion 70 is connected to an end of the guide portion 72 which is axially opposed to the nut 82. The straight portion 70 extends axially said end of the guide portion 72.

In this example, the guide portion 72 extends circumferentially in a direction opposite to the thread direction o f the screw 24. When the guide means 56 are lo cated into the guide portion 72 of the groove of the housing, the axial travel o f the screw 24 per turn of the nut 28 is smaller than the lead of said screw.

Under a constant torque applied to the input member 20, the valve operator assembly 10 has a variable lead. A first lead is obtained when the guide means 56 are engaged within the guide portion 72 o f the groove of the housing and a second lead with higher value is obtained when the guide means 56 are engaged within the straight portion 70 of said groove.

The groove 58 and the guide means 56 are provided in such a way that, when operating the gate valve 12, the guide means 56 are lo cated into the guide portion 72 o f the groove at the beginning o f the valve opening and at the end o f the valve closing, and said guide means 56 are lo cated into the the straight portion 70 during the other operating runs .

Although the invention has been illustrated on the basis of a valve operator comprising a screw connected to the valve stem o f the gate and a nut connected to the input member, it should be understood that the invention can be applied with a screw connected to the input member and a nut connected to the valve stem. In this case, the nut acts as the translating element and the screw acts as the rotating element. In this case, the guide means are coupled to the nut. The guide means radially protrude outwards with respect to the outer surface o f the screw.

In the described examples, the guide means are connected or coupled directly to the screw or to the nut. Alternatively, it could be possible to foresee an indirect connection between the guide means and the screw, or the nut, in which one or more other components are interposed therebetween. In the disclosed examples, the guide means are provided with a rotatable roller in order to limit friction with the groove of the housing. Alternatively, other component may be foreseen to engage within the groove, for example a ro lling bearing, a plain bearing or a fixed pin sliding along the groove . Guide means may also have a combined movement of rolling and sliding along the groove.

In another variant, it could also be possible to use several guide means connected to the screw or the nut. In this case, it is necessary to provide for each guide means one associated groove on the housing. In the disclosed examples, the groove is formed directly in the thickness of the housing. Alternatively, the groove may be delimited by two separate plates attached directly to the housing by any other appropriate means.

In another variant, it could also be possible to foresee another type of guide member on the housing to cooperate with the guide means, for example two separate circular wires secured to housing may be provided instead of a groove. In this case, the guide means engage between the wires .

In the disclo sed examp les, the guide member comprises a straight anti-rotation portion extending purely axially. Alternatively, the guide member may comprise an anti-rotation portion extending substantially or generally axially so as to guide axial movements and to prevent angular movement of the translating element relative to the housing. In this case, the anti-rotation portion may have a very small angle with regard to the axis of the translating element, for example lower than 5 ° and preferably lower than 2° .

In the disclosed examples, the valve operator assembly is designed to obtain to obtain two different leads with a constant lead thread o f the screw. Alternatively, it could be possible to foresee more than two leads for the assembly while maintaining a constant lead for the thread o f the screw.

The invention has been illustrated on the basis o f a valve operator assembly comprising a roller or a ball screw mechanism. Otherwise, the invention can also be applied to a valve operator assembly having other type of transmission mechanism adapted to convert a rotation into a linear movement, for instance a direct threaded connection. In this case, the outer thread of the screw engages directly the inner thread of the nut without interposition o f rolling elements . However, such transmission mechanism requires large actuation torques .

Although the invention has been illustrated on the basis of a valve operator assembly for gate valve, it should be understood that the invention can also be used with other types of valves, for instance control or regulation valves or choke valves . The valve operator assembly may be used for instance with a surface gate or a subsea valve gate which may be actuated by a remote operating vehicle (ROV) torque tool or an actuator.