TECHNICAL FIELD

The present description relates to a bidirectional valve with rotating shutters, in particular a bidirectional valve which can be used as a shut-off valve in oil and gas pipelines to block a flow of fluid for emergency or maintenance.

FRAMEWORK OF THE DESCRIPTION

US 2389194 describes a valve comprising two shutters which can rotate in the cavity of a hollow body between a closed position and an open position of the valve. The shutters must be rotated by exercising a relatively high torque to open the valve, due to the pressure of the fluid acting on a shutter or both shutters when the portion of the cavity arranged between the shutters is free of fluid.

FR 871273 A describes a valve according to the preamble of claim 1, while EP 2119946 Al and US 3364944 describe other valves with two shutters. These known valves include outer ducts for regulating the inner pressure, so that these valves are rather complex, bulky and expensive.

SUMMARY OF THE DESCRIPTION

The object of the present description is therefore to provide a valve free from these drawbacks. Said object is obtained with a valve and a method whose main features are specified in the attached claims.

Thanks to its particular bypass, the valve according to the present description can be opened by a smaller torque on the shutters, since one or more auxiliary valves can put in communication the intermediate portion of the cavity arranged between the shutters with at least one end portion of the cavity, through the bypass, thus balancing the pressure exerted by the fluid on the shutters. The bypass can comprise a main duct and secondary ducts formed in the hollow body, so as not to increase the bulk and the number of components of the valve, especially if the hollow body and the components arranged therein are substantially symmetrical with respect to a plane substantially perpendicular to the longitudinal axis of the hollow body and passing through the intermediate portion of the cavity.

The main duct of the bypass can be substantially rectilinear, substantially parallel to the longitudinal axis of the hollow body and/or can pass through the latter entirely, so as to simplify the manufacture and maintenance of the valve, especially if the main duct opens on the sides of the hollow body provided with openings to the outside.

The secondary ducts of the bypass can be substantially straight and arranged along axes that pass through a window in the hollow body, so as to further simplify the manufacture and maintenance of the valve, especially if this window is the same window that is used to access a seat of a shutter.

One or both auxiliary valves may comprise a gate suitable to slide in a seat formed in the hollow body to open or close the bypass, so as to further simplify the manufacture and maintenance of the valve, especially if this seat is open to the outside of the hollow body and is covered by a bonnet in which a stem connected to the gate can translate.

The gate of the auxiliary valves can be arranged between at least two sleeves which are urged by springs and are slidably inserted, partially and coaxially, in two portions of the main duct that lead to the seat of the gate, so as to improve the seal of the auxiliary valves, especially if at least one auxiliary duct can connect in the gate these two sections when the gate is open. At least one through hole can connect this auxiliary duct with the seat of the gate to reduce the pressure on the gate, so as to reduce the force necessary to operate it.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and characteristics of the valve according to the present description will become apparent to those skilled in the art from the following detailed and non-limiting description of an embodiment thereof with reference to the accompanying drawings in which: figure 1 shows a perspective view of the valve in the closed position;

figure 2 shows section II-II of figure 1;

figure 3 shows section III-III of figure 2, enlarged;

figure 4 shows the valve of figure 2 during the opening;

figure 5 shows section V-V of figure 4, enlarged;

figure 6 shows the valve of figure 2 in the open position.

EXPLANATORY EMBODIMENTS

Referring to figures 1 and 2, it is seen that the valve according to a preferred embodiment comprises a hollow body 1 which extends along a longitudinal axis L and includes a cavity 2 which extends mainly along the longitudinal axis L, mutually connecting at least two openings 3, 4 which lead to the outside of the hollow body 1. The openings 3, 4 of the hollow body 1 may in turn be connected to external ducts, for example by means of flanges (not shown in the figure) fixed to the hollow body 1 with screws. Preferably, the cavity 2 has a substantially cylindrical shape. The openings 3, 4 act respectively as inlet and outlet, or vice versa, depending on the direction of a flow of fluid that passes through the hollow body 1.

The hollow body 1 also comprises at least two shutters 5, in particular being the same, which are fastened to shafts 6 that can rotate around axes substantially perpendicular to the longitudinal axis L.

The shutters 5 can rotate between a closed position, shown in figure 2, in which they abut against respective shoulders la in the hollow body 1, in particular formed on an intermediate portion of the hollow body 1, and an open position, shown with dashed lines in figure 2, in which the shutters 5 are both rotated at about 90° and are housed at least partially in respective seats 9 formed in the hollow body 1 on one side of the cavity 2

At least one actuator 10 can be connected to the hollow body 1, for example through a transmission 11 with toothed wheels, to rotate the shafts 6 of the shutters 5, in particular at the same time and/or with opposite rotation directions. Depending on the type of application, underwater or above-ground, and of the torque required for the operation of the shutters 5, the actuator 10 can be manual or automatic of the pneumatic, electric or hydraulic type. In the illustrated embodiment, the actuator 10 is for example a single-acting hydraulic rotary actuator provided with a safety closure device, so-called "fail safe", comprising a return spring.

The seats 9 of the shutters 5 in the hollow body 1 can be accessed from the outside through windows lb formed in the hollow body 1 and closed by respective covers 12 tightly fixed on the hollow body 1 by means of gaskets and screws. The shutters 5 can comprise a disk-shaped element joined with a screw to an arm 13 which extends radially from this disk-shaped element and ends with an attachment 14 keyed to a respective shaft 6.

At least one bypass provided with one or more auxiliary valves 20 connects at least one end portion 2a, 2b of the cavity 2 of the hollow body 1 which leads towards the opening 3 or 4 with an intermediate portion 2c of the cavity 2 of the hollow body 1 arranged between the shoulders la for the shutters 5. In the present embodiment the bypass mutually connects the two terminal portions 2a, 2b and the intermediate portion 2c of the cavity 2.

This bypass preferably comprises at least one main duct 21 which is connected to the terminal portions 2a, 2b and to the intermediate portion 2c of the cavity 2 through one or more respective secondary ducts 22a, 22b, 22c. Preferably, the main duct 21 is substantially rectilinear and substantially parallel to the longitudinal axis L. Preferably, the main duct 21 passes through the entire hollow body 1 and leads to the sides provided with the openings 3, 4, where it is closed by caps 23 (which are not visible in figure 1 as they are covered by the actuator 10). The main duct 21 and/or the secondary ducts 22a, 22b, 22c are preferably formed in the hollow body 1, in particular by removing material from one or more walls surrounding the cavity 2.

The hollow body 1 can be substantially right-prism-shaped, wherein the longitudinal axis L is substantially parallel to the axis of the prism. The main duct 21 is preferably adjacent to a comer of the hollow body 1, in particular arranged near the side of the hollow body 1 opposite to the side comprising the windows lb of the hollow body 1 and/or near the side of the hollow body 1 adjacent to the transmission 11. The valve according to the present embodiment comprises in particular at least two auxiliary valves 20 arranged along the main duct 21 between at least one secondary duct 22a or 22b which leads into an end portion 2a or 2b of the cavity 2 and one or more secondary ducts 22c, in particularly at least two secondary ducts 22c, which lead into the intermediate portion 2c of the cavity 2.

Preferably, one or more of said secondary ducts 22a, 22b and/or 22c are substantially rectilinear and arranged along axes A which pass through a window lb in the hollow body 1. Axes A in particular form with the longitudinal axis L an acute angle a, in particular between 60° and 70°.

Preferably, the hollow body 1 and the components arranged therein are substantially symmetrical with respect to a plane C perpendicular to the longitudinal axis L and passing through the intermediate portion 2c of the cavity 2.

Referring to figure 3, it is seen that at least one of said auxiliary valves 20 preferably comprises a gate 24 which can slide in a seat 25 formed in the hollow body 1 to open or close the bypass, in particular to open or close a section of the main duct 21. The gate 24 can slide along a direction D substantially perpendicular to the longitudinal axis L. Preferably, the seat 25 of the gate 24 has a substantially cylindrical shape having an axis substantially parallel to the direction D. The seat 25 is open towards the outside of the hollow body 1 and is covered by a bonnet 26 provided with at least one axial hole 27 with one or more gaskets. A stem 28 connected to the gate 24 can translate in the axial hole 27 of the bonnet 26 to operate the gate 24 from the outside of the hollow body 1, in particular by means of an actuator (not shown in the figures) provided with a movable member fixed to the stem 28, for example by means of a threaded portion 29 thereof.

The gate 24 is arranged between at least two sleeves 30 which are slidably inserted, partially and coaxially, into two portions of the main duct 21 which lead into the seat 25 of the gate 24. The sleeves 30 are urged towards the gate 24 by springs 31 arranged in turn in the main duct 21 between a sleeve 30 and a shoulder, in particular formed by a narrowing 32 in the main duct 21 or by at least one spacer 33 connected to a cap 23. The spacer 33 has a substantially cylindrical shape substantially with the same diameter of the main duct 21. Gaskets 34 maintain the seal between the main duct 21 and the sleeves 30, thus avoiding direct passage of fluids toward the seat 25 of the gate 24.

The gate 24 preferably comprises at least one auxiliary duct 35 suitable to connect, in an open position of the gate 24, the two sleeves 30, namely the two sections of the main duct 21 which lead into the seat 25 of the gate 24. The auxiliary duct 35 of the gate 24 is substantially parallel to the main duct 21 and has substantially its same diameter. In a closed position of the gate 24, shown in figures 2 and 3, the two sections of the main duct 21 that lead into the seat 25 of the gate 24 are not connected to each other and are closed by an end portion of the gate 24, which has a substantially prismatic shape with at least two flat surfaces parallel to each other, each in contact with either sleeve 30.

At least one through hole 36 preferably connects the auxiliary duct 35 of the gate 24 with the seat 25 of the gate 24. The axis of the through hole 36 is substantially perpendicular to both the sliding direction D of the gate 24 and the longitudinal axis L.

The spacer 34 is provided with one or more radial openings 37 suitable for connecting the sleeve 30 adjacent to the spacer 34 with a secondary duct 22a or 22b, which preferably leads into the main duct 21 at the spacer 34.

Referring to figures 4 and 5, it is seen that during the opening of the valve, the auxiliary valves 20 are opened simultaneously or one after the other by moving their shutters 24 along the direction D. Thus, a fluid 38 flowed into the hollow body 1 and contained in an end portion of the cavity 2, for example flowed through the opening 3 and contained in the terminal portion 2a, passes through a first auxiliary valve 20, the main duct 21, the secondary ducts 22c and reaches the intermediate portion 2c of the cavity 2. Then, once the second auxiliary valve 20 (if present) is opened, the fluid 38 passes through the secondary duct 22b and reaches the terminal portion 2b of the cavity 2, after which it flows out of the opening 4 of the hollow body 1.

With reference to figure 6, it can be seen that when at least the intermediate portion 2c of the cavity 2 contains the fluid 38, preferably also when the end portion 2b of the cavity 2 contains the fluid 38, the actuator 10 rotates the shutters 5 in the seats 9, so that the fluid can pass through the cavity 2 of the hollow body 1 between the openings 3, 4. The operating steps indicated above are performed in reverse to close the valve according to the present description.

Any variants or additions may be made by those skilled in the art to the embodiment herein described and illustrated, while remaining within the scope of the following claims. In particular, further embodiments may comprise the technical characteristics of one of the following claims with the addition of one or more technical features described in the text or illustrated in the drawings, taken individually or in any combination thereof.