DESCRI PTION

Technical sector of the invention

The present invention relates to a to innovative torque seal ball valve, with an upper or side inlet, and with a metal seat. This type of valve is used in numerous applications, in particular in the "Oil and Gas" sector for the interception of a flow in hydraulic pipes.

Background art

As it is known in an extremely synthetic way, a ball valve comprises a spherical shutter equipped with a coaxial cylindrical cavity to the flow able to rotate with a rotation of 90°. The valve allows the closing, opening and reduction of the flow. Said ball valve comprises a body, a seat, a shutter (the real ball), a stem and an actuation of the stem itself. The body is generally divided into parts screwed into one another or flanged together; for medium-low pressures brass worked by stamping is used, for higher pressures carbon steel or stainless steel is preferred; due to their characteristics, ball valves are well suitable for production by forging, and therefore they can be produced in practically any metal material. They are also widely used for applications of not too hot corrosive fluids, of ball valves made of synthetic material, especially polyvinyl chloride (PVC), but also polypropylene (PP) and polyviny!idene fluoride (PVDF). The shutter is usually made of the same material as the body (stainless steel with less noble metal bodies is often used) and has a very accurate surface finish to allow good contact with the sealing seat. This consists of two shaped rings, mainly in polytetrafluoroetbylene (PTFE); the stem is made of the same material as the ball or the body, and is also sealed by suitably shaped PTFE rings.

In its open position the valve practically becomes a section of a pipe, whereas in its closed position the hole inside the ball is isolated due to the sealing seats. Its actuation is very fast (only a quarter of a turn is necessary) and therefore it allows a rapid closing and opening: this is both an advantage and a drawback, as abrupt openings and closings can cause water hammer that could damage neighboring equipment. Furthermore, its limited stroke, even if allowing an easy actuation, does not permit the regulation of the flow except in a very approximate way. The traditional ball valve cannot be drained, as the sealing seats retain a portion of the fluid inside the ball; therefore, perishable products can deteriorate and other ones can solidify.

In the case of a full passage torque seal ball valve, i.e. a valve whose passage diameter is equal to the inner diameter of the upstream and downstream pipe, has a rather low pressure drop, equal to that of the pipe - naturally if the valve is fully open. In particular, according to the known art, it is not possible to internally clean a torque seal ball valve without dismantling it, as even with the shutter completely open it is not possible to carry out the passage to its inside of the equipment used for cleaning the pipes.

Such difficulty is due to the fact that the torque seal ball valves of known type in the phase of complete opening have a non-cylindrical cavity or a cylindrical cavity of the spherical shutter, which is not completely coaxial with respect to the flow. This entails that, when the passage of the equipment used for cleaning of the pipes is made, plant shutdowns must be carried out, with the consequent additional costs due to such maintenance.

There is, therefore the need to define an innovative torque seal ball valve that is free from the drawbacks mentioned above.

Summary of the invention

The present invention aims to solve the technical problem consisting in carrying out in a practical and fast way the passage of the equipment used for cleaning the inside of the pipeline and consequently also the passage inside a torque seal ball valve, without having to disassemble and reassemble the same, according to what is indicated in the prior art.

For this purpose, according to the present invention, the cylindrical cavity of the shutter of the ball valve has a first and a second eccentricity, so that their combined effect allows the passage of the equipment used for cleaning the pipes, according to the characteristics set forth in the independent product claim.

Further preferred and/or particularly advantageous embodiments of the invention are described according to the characteristics set out in the attached dependent claims.

Brief description of the drawings

The invention will now be described with reference to the attached drawings, which illustrate some non-limiting examples of application, in which:

- Figure 1 is a cross-section longitudinal view of a torque seal ball valve,

- Figure 2 is a detail of the spherical shutter in a partial cross-section of the valve of Fig. 1, showing the first eccentricity of the shutter itself, according to the present invention, and - Figure 3 is a further detail of the spherical shutter of the valve of Fig. 1, showing the second eccentricity of the shutter itself, according to the present invention.

Detailed description

With reference to the aforesaid figures, Figure 1 is a longitudinal cross-section view of a torque seal ball valve 100. The ball valve 100 comprises a valve body 1, a first inlet joint 2 and a second outlet joint 3 in connection with the central spherical shutter 4 (shown in detail in Figures 2 and 3). In particular, the spherical shutter 4 has at its inside a passage hole 5, such passage hole according to the present invention being made in an offset position with respect to the spherical shutter itself.

In the fully open position of the valve 100, shown in Figure 1, the spherical shutter 4 is positioned in such a way, that the fluid coming from the first inlet joint 2 passes completely inside it and reaches the second outlet joint 3. In addition, the fully open position of the shutter has a concentric internal passage hole, i.e. coaxial with respect to the pipe 2, 3. This therefore allows, as there are no obstacles of any kind, even the passage of the cleaning element inside the shutter.

The spherical shutter 4 according to the invention, with reference to Figure 2, shows a first offset or first eccentricity El between the center of the spherical element indicated with C, i.e. the geometric center of the spherical shutter assimilated to an ideal sphere, and the center of rotation of the spherical shutter 4 indicated with R, i.e. the projection of the axis around which the spherical shutter performs its 90° rotation (passing from the closed to the open position).

The effect of this first eccentricity is to make the spherical shutter to contact its sealing seat 6 only in the last percentage of the closing stroke. As a consequence, a very low torque is sufficient to move the shutter even in the presence of very high pressure differentials. Moreover, in this way, due to the "unbalancing " effect, the valve increases its sealing capacity as the upstream pressure increases, the one of the inlet joint 2. This guarantees a reliable sealing even in the presence of very high pressure differentials.

The spherical shutter 4 according to the invention, with reference to Figure 3, shows a second offset or a second eccentricity E2 between the center of the spherical element indicated with C, i.e. the geometric center of the spherical shutter assimilated to an ideal sphere, and the center of the passage hole 5 of the spherical shutter 4 indicated with Rl.

Therefore, according to the present invention, the cylindrical cavity of the spherical shutter 4 has a first and a second eccentricity, so that their combined effect allows the passage of the equipment used for cleaning the pipes.

According to a preferred embodiment, the dimensionless ratio between the first eccentricity El and the second eccentricity E2 is in the range between 0.8 and 1.2. Advantageously, such ratio is equal to 1. Preferably, the spherical shutter 4 is integral, i.e. it is made in a single piece.

In addition, the ball of the shutter 4 can be mounted on a pin to allow a reliable operation and a low torque during the closing stroke even under extreme service conditions.

Advantageously, the spherical shutter 4 is supported by dry self-lubricating bearings to ensure a long service life.

In addition to the embodiments of the invention, as described above, it is to be understood that there are numerous further variants. It must also be understood that said embodiments are only examples and do not limit neither the object of the invention, nor its applications, nor its possible configurations. On the contrary, although the above description makes it possible for the technician to implement the present invention at least according to an exemplary configuration thereof, it must be understood that numerous variations of the components described are conceivable, without thereby departing from the object of the invention, as defined in the appended claims, interpreted literally and/or according to their legal equivalents.