Title: "Fluid on-off valve"

DESCRIPTION Technical Field

The present invention refers to a fluid on-off valve. More specifically the invention relates to a fluid on-off valve for an industrial plant, in particular for an oilrig, of the type comprising a valve body, a fluid path in said valve body, extending according to a longitudinal axis between an inlet mouth and an outlet mouth, a plug seat in said valve body and a plug mobile from and towards said plug seat.

Background Art

As it is well known, there is a need to intercept a fluid, for example an oil product, so as to ensure an interruption of its flow in a pipe as necessary. For this purpose, the pipe or tube is provided with on-off valves of the type specified above. Such valves, whilst satisfying the purpose and being widely used, nevertheless have a recognised drawback that is represented by the fact that they comprise means for intercepting the fluid that occupy a lot of space along the fluid path, also in open valve position, they cause substantial pressure losses and they are heavy.

The technical problem forming the basis of the present invention is to devise a valve of the specified type that has structural and functional characteristics such as to overcome the aforementioned drawbacks with reference to the prior art. Disclosure of Invention

Such a problem is solved by a valve of the specified type in which the plug is substantially plate-shaped and is supported so that it can rotate substantially like a flag on a rotation axis extending transversally to said longitudinal axis between a closed valve position in which said plug is in contact against said plug seat and an open valve position in which said plug is in a spaced relationship from said plug seat, away from said fluid path.

The valve according to the invention, in conditions with the valve open, has a free passage of the fluid along the path, and also a free

passage along the path itself of means for cleaning the valve and the pipe, such as so-called "pigs". The valve according to the invention thus has the great advantage that its presence along the pipe does not prevent the free passage of such "pigs". Further characteristics and advantages of the valve according to the invention shall become clearer from the following description of an example embodiment thereof, given for indicating and not limiting purposes with reference to the attached drawings. Brief description of the drawings In such drawings:

Figure 1 represents a view from above of a fluid on-off valve made according to the invention;

Figure 2 represents a top view of the valve of Figure 1;

Figure 3 represents a view of the valve of Figure 2 taken according to the arrow III;

Figure 4 represents an enlarged section view of the valve of Figure 1 taken according to the line IV-IV;

Figure 5 represents an enlarged section view of the valve of Figure 1 taken according to the line V-V; Figures 6 and 7 represent further enlarged section views of details of the valve of Figure 4;

Figures 8 to 11 represent section views of the valve of Figure 1 in different steps of its operation;

Figure 12 represents a section view of a valve according to the invention in accordance with an alternative embodiment; and

Figure 13 represents a section view of a valve according to the invention in accordance with a further alternative embodiment. Modes for Carrying Out the Invention

With reference to the attached figures, a fluid on-off valve in accordance with the invention is globally indicated with 10.

The valve 10 comprises a valve body 11, a fluid path 12 in the valve body 11 , extending according to a longitudinal axis XX between an inlet mouth 13 and an outlet mouth 14.

In particular, the valve body 11 is preferably made from molten

steel and is intended to be inserted along a pipe, not represented, through opposite end flanges 15 and 16 and defines the fluid passage 12, which has a substantially circular section with a large diameter, for example 400mm, or greater diameters. The valve 10 has a plug seat 18 made in the valve body 11 lying obliquely with respect to the longitudinal axis XX, for example according to a plane inclined by 45° with respect to such an axis XX.

The valve 10 also comprises a plug 19 that is mobile in the valve body 11 from and towards the plug seat 18. Advantageously according to the invention, the plug 19 is supported so as to be able to rotate on a rotation axis YY extending transversally to the longitudinal axis XX. In particular, the plug 19 is essentially a substantially elliptical plate with grommets 20 and 21 in distance relationship intended to receive a pin 22 on which such a plug can be moved angularly substantially like a flag.

The plug 19 can move angularly between a closed valve position in which it is in contact against the plug seat 18 and an open valve position in which it is in a spaced relationship from such a plug seat 18, away from the fluid path 12. It should be noted that the pin 22 is supported in the valve body

11 and has at least a first end 23 associated with said valve body 11 and a second opposite end 24 accessible from the outside of the valve body 11. In a preferred example embodiment of the valve 10 according to the invention, such a second end 24 of the pin 22 has an associated control wheel 25. Such a control wheel 25 is foreseen to actuate the valve 10 between the closed position and the open position, as shall be described hereafter.

The valve 10 is completed with a shaft 26 having opposite ends, a first end 27 being hinged to the valve body 11 and a second opposite end 28 being associated with the plug 19.

The first end 27 of the shaft 26 is hinged through a pin 29 to the valve body 11, which is provided with grommets 30 and 31, if necessary.

At the second opposite end 28 of the shaft 26 associated with the

plug 19, the valve 10 also comprises a sliding block 32, slidably guided in the radial direction AA to the rotation axis YY, preferably along guides 33 formed in the plug 19 and extending according to such a radial direction AA. The guides 33 are suitable for holding the sliding block 32 constantly in contact with the plug 19.

The valve 10 according to the invention also comprises control means 34 active on the shaft 26 for controlling the opening and closing of the plug 19. The control means 34 comprise a screw 35 and a female screw 36, the screw 35 being rotatably supported by the plug 19 along the radial direction AA and the female screw 36 being mounted onto the sliding block 32.

In particular, the screw 35 has a first free end rotatably supported by a first support 35A and a second end axially held and rotatably mounted by a second support 35B, the first and second supports being fixed to the plug 19.

The control means 34 also comprise a mechanical transmission between the screw 35 and the control wheel 25, such a mechanical transmission comprising a toothed pair 37 with bevel gears. In particular, the toothed pair 37 comprises a first bevel gear 38 fitted onto the second end of the screw 35 and a second bevel gear 39 fitted onto the pin 22 in a position located between the grommets 20 and 21. Such a toothed pair can have a transmission ratio other than 1: 1, and, therefore, it can act as a reducer or a multiplier of the actuation speed and consequently of the actuation forces. Moreover, such forces can again be modified by the selection of the pitch of the screw-female screw 35-36.

It should be noted that at the pin 29 and in particular at an end 29A thereof that is accessible from the outside, an auxiliary control wheel 29B is foreseen. Such an auxiliary control wheel 29B is active on the shaft 26 to actuate the valve 10 between the closed position and the open position during its maintenance and/ or assembly operations, as well as constituting a safety element for actuation in the case of failure on the control wheel 25.

Advantageously, the valve 10 according to the invention also comprises a connecting rod 40 having opposite ends with a grommet respectively crossed by the pins 22 and 29, so as to ensure the constancy of the inter-axis between said pins on a precise value, irrespective of deformations and /or expansions of the valve body 11 and so as to close the forces deriving from the reaction of the shaft 26 onto a triangle and not transmit them to the body of the valve.

Hereafter, we shall describe the operation of the valve 10 in accordance with the invention with reference to an initial condition thereof with the valve closed, represented in Figure 8.

In this closed valve position, the plug 19 is kept in contact pressing against the plug seat 18 after displacement of the sliding block 32 in a limit switch position thereof towards the free end of the screw 35. In this position, the shaft 26 acts as a rafter on the plug 19 and ensures the aforementioned pressing contact. Thanks to the irreversibility of the screw 35-female screw 36 coupling, the position of the sliding block 32 remains constant and it is not necessary to keep the screw 35 under torque or else locked.

The desired opening of the valve 10 is carried out by acting upon the control wheel 25. In particular, and through the toothed pair 37 with bevel gears and the screw 35-female screw 36 coupling the sliding block 32 moves towards the second end of the screw 35. In this step, illustrated in Figure 9, the shaft 26 acts as a stay rod taking the plug

19 away from the plug seat 18. Continuing in the action on the control wheel 25, the plug 19 moves increasingly further away from the plug seat 18 (as illustrated in Figures 10 and 11) until it reaches an open valve position in which the female screw 36 is in close-together relationship with the second end of the screw 35, the plug 19 lies substantially parallel to the longitudinal axis XX with free passage for the fluid in the pipe and thus also with free passage of the so-called

"pigs" for cleaning and checking the pipes. Thus, the shaft 26 also lies substantially parallel to the longitudinal axis XX.

In order to take the valve 10 back into its closed position it is sufficient to go backwards, by acting upon the control wheel 25 and

upon the transmission in the opposite direction with respect to the previous one, with the shaft 26 going back to act as a rafter.

During maintenance and/ or assembly operations of the valve 10 according to the invention, or in any case during emergency operations, when the control means 34 are inoperative or have broken down, the desired movement of the plug 19 from and towards the plug seat 18 is obtained by acting upon the auxiliary control wheel 29B, which in turn causes such a desired movement of the plug 19.

For so-called strict services, it is possible to mount a "by-pass" onto the plug itself suitable for further reducing the closing forces and for preserving the inevitable erosion of the last closing area of the seat, concentrating said stresses upon this "by-pass" element. In this case the body itself of the plug has a valve with a small diameter, of the type

"plate check- valve", housed in it, which is engaged lastly by the sliding block sliding on the guide of the plug during its closing stroke.

In the same way, it shall be this same valve with a small diameter that opens first, totally automatically based upon the thrust of the intercepted fluid itself, allowing the pipe to be filled downstream of the valve and ensuring that the plug opens when there is no or almost no pressure difference.

It should be noted that the on-off valve described above is of the type in which the opening and closing of the valve and therefore the interception of the fluid in the two directions is obtained through an external command, in particular by acting upon the control wheels. It should be also noted that the on-off valve described above can take up and maintain any intermediate position between the open position and the closed position, for which reason the valve described above can also perform the function of adjusting the flow of the fluid.

With reference to Figure 12 an on-off valve in accordance with an alternative embodiment of the invention is described hereafter, globally indicated with 110.

In the rest of the description, the parts structurally and functionally the same as those described previously with reference to the valve 10 keep the same reference numerals and shall not be

described any further.

The valve 1 10 comprises control means 134 of the shaft 26, in turn including a fluid cylinder-piston group 111 that extends in a direction

ZZ perpendicular to the longitudinal axis XX, said cylinder-piston group 111 having a cylinder 112 fixedly connected to the valve body 11 and a piston 113 acting on the shaft 26.

The desired opening and closing of the valve 110 are obtained through the cylinder-piston group 111, which controls the plug 19 to go away from and towards the plug seat 18 through the shaft 26 and the sliding block 32.

Hereafter, an on-off valve in accordance with a further embodiment of the invention is described, which is of the so-called free-flow or check valve type, in which the opening and closing of the valve are determined by the flow itself of the fluid, in the sense that the flow of the fluid has free passage in one direction, whereas it is intercepted in the other direction.

Such a valve comprises just the valve body 11, the plug seat 18 and the plug 19 that is mobile from and towards the plug seat 18, such a plug 19 being supported so as to be able to rotate freely substantially like a flag on the rotation axis YY.

In operation, a fluid that flows along the fluid path 12 from the opening mouth 13 towards the closing mouth 14 causes the plug 19 to move away from the plug seat 18, and consequently cause the valve to open, achieving the desired free-flow function. On the other hand, the passage of fluid from the closing mouth 14 to the opening mouth 13 causes the plug 19 to move towards the plug seat 18 and causes it to be held against the seat, obtaining the closing of the valve and the interception of the fluid.

With reference to Figure 13, a further example of the valve according to the invention is described, globally indicated with 210.

Also in this case, in the rest of the description the parts structurally and functionally the same as those described previously with reference to the valve 10 keep the same reference numerals and shall not be described any further.

The valve 210 comprises control means 234, acting on the shaft 26 and comprising a screw 235-female screw 236 pair of the reversible type, in particular of the ball recirculating type. Said pair comprises a screw 235 associated with the plug 19 and a female screw 236 associated with the sliding block 32.

In conditions with the valve closed, the shaft 26 and the screw 235 form an acute angle open towards the outlet mouth 14.

In operation, a fluid that flows in the fluid passage 12 from the opening mouth 13 towards the closing mouth 14 causes the plug 19 to move away from the plug seat 18, thanks to the reversibility of the screw 235-female screw 236 pair, and consequently it causes the valve

210 to open, achieving the desired free-flow function.

On the other hand, the passage of fluid from the closing mouth 14 to the opening mouth 13 causes the plug 19 to move towards the plug seat 18 and causes it to be held against the seat, obtaining the closing of the valve 210 and the interception of the fluid.

Such a valve 210 thus performs the function of a "stop-check" valve whilst still, though its own control means maintaining the on-off valve function, including the ability to adjust the flow of the fluid, and further ensuring a free passage of the so-called "pig" elements to clean the valve itself.

In conclusion, the main advantage of the on-off valve according to the invention is that it ensures a free passage of the fluid thanks to the rectilinear extension free from chokes and possible cleaning elements, like so-called "pigs", in conditions with the valve open.

A further advantage of the valve according to the invention is that, in open position, it creates lower pressure losses.

A further advantage of the valve according to the invention is that it is structurally simple and light. Advantageously, the torque necessary to actuate the valve does not have excessive variations between the open/ closed positions due to the absorption of the forces by the "rafter" acting on the back of them plug, which is very important in the case of use of servomotors, and it is also possible to omit a gear handle because it is intrinsic in the bevel gear

system supported by the reduction in stress due to the pitch of the screw-female screw.

Of course, a man skilled in the art can bring numerous modifications and variants to the valve described above in order to satisfy contingent and specific requirements, all of which are covered by the scope of protection of the invention as denned by the following claims.