Patent Description:
There is a need, for this type of applications, to use materials which allow to ensure the required performance also at high temperatures. In particular, gaskets or other sealing and support members of the valve member, conventionally a floating ball made of soft materials, e.g., polymer materials, can not be used, and metal materials and graphite must be used. For example, metal materials are used to obtain the seats of the ball, while graphite is used for the sealing gaskets.

A problem associated with the use of these materials is the size variation thereof caused by the thermal expansions. Such a problem is particularly emphasized by the fact that the valve is assembled at room temperature (<NUM>) but needs then to work at high higher temperatures (<NUM> to <NUM>). Examples of shut-off valves according to the state of the art are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

In order to solve such a drawback, it is known to preload the members acting on the ball, in particular the sealing members, in jargon referred to as "seats", so as to compensate for the thermal expansions on average.

A valve of this type is known as a "<NUM>-piece" valve because it is formed up of a central valve body, which accommodates the spherical shutter and the related sealing members, and two end connecting members connected by bolted coupling to the central body, each suitable to connect a respective fluid inlet or outlet duct.

The elastic compensation members, conventionally springs, are supported by an inner annular surface of the respective connecting members.

This construction, commonly known as <NUM>-piece construction, has the disadvantage that the removal of the central body from the ends, for example to perform maintenance on the functional members of the valve accommodated in the central body, results in the disassembly of the inner components (ball, seats, and possible springs)which are no longer held in place by the ends themselves.

The present invention pertains to such a context by aiming at providing a valve capable of overcoming the aforesaid drawbacks.

In particular, it is an object of the present invention to suggest a fluid shut-off valve of the above-mentioned three-piece type which allows it to be subjected to a seal test without the need for the two connecting members to the respective ducts of the system.

It is another object of the invention to suggest a shut-off valve capable of combining the above functionality during maintenance or seal test with the possibility of intercepting fluids with temperature up to <NUM>.

Such objects are achieved by a shut-off valve according to claim <NUM>, an assembly according to claim <NUM>, and a test method according to claim <NUM>. The claims dependent thereon show preferred variants.

The features and advantages of the shut-off valve according to the invention will however be apparent from the following description of preferred embodiments thereof, given by way indication and not by way of limitation, with reference to the accompanying drawings, in which:.

With reference to the aforesaid drawings, reference numeral <NUM> identifies, as a whole, a fluid shut-off valve according to the present invention.

Valve <NUM> comprises a valve body <NUM> which extends axially along a body axis Z between two opposite openings <NUM>, <NUM> for the inlet and outlet of the fluid.

The valve body <NUM> is provided, at each end thereof delimiting a respective opening <NUM>, <NUM>, with connection means <NUM> to a respective joining member <NUM> suitable to be connected to a fluid inlet or outlet duct.

In certain embodiments, the connection means <NUM> consist of bolts <NUM>'.

The valve further comprises a shutter <NUM> rotatably placed in the valve body <NUM> between the two inlet/outlet openings <NUM>, <NUM>.

For example, the shutter <NUM> is a floating ball shutter.

The shutter <NUM> is crossed by an axial passageway <NUM> suitable to put the two opposite openings <NUM>, <NUM> into fluid communication and is rotatable between a closed position, in which it prevents the passage of the fluid from one opening to the other one, and an open position, in which it allows the passage of the fluid between the two openings of the valve body <NUM>.

The valve further comprises two shutter seats <NUM> which rotatably support shutter <NUM>.

Each shutter seat <NUM> is supported by a respective drawer <NUM>. In certain embodiments, seat <NUM> and drawer <NUM> are made in one piece in a single body.

Each drawer <NUM> is elastically affected by a respective elastic compensation member <NUM> which applies to drawer <NUM> a compensation pressure directed towards the shutter <NUM>.

Therefore, by virtue of the elastic compensation members <NUM>, the seats <NUM> with respective drawers <NUM> are capable of ensuring the fluid sealing effect on the shutter during any expansion and/or contraction caused by the temperature.

According to an aspect of the invention, a head <NUM> defining an axial abutment for a respective elastic compensation member <NUM> is inserted with shape and/or force coupling into each of the inlet/outlet openings <NUM>, <NUM> of the valve body <NUM>.

In other words, each elastic compensation member <NUM> does not rest on a respective joining member <NUM>, as in the valves of the known art, but it is retained in the valve body by a respective head <NUM> also inserted into the respective opening <NUM>; <NUM> of the valve body <NUM>.

Each head <NUM> has an outer side wall 50a which sealingly engages an inner side wall 10b of the valve body <NUM>.

Each head <NUM> is axially crossed by a head opening <NUM> for the passage of the fluid.

Therefore, the presence of the heads <NUM> does not significantly affect the fluid operation of the valve, not causing losses of load for the passage of the fluid through the valve.

Moreover, each head <NUM> is inserted into the respective opening <NUM>; <NUM> without engaging the connection means <NUM> with the joining member <NUM>.

In other words, the presence of the heads <NUM> does not affect the connection of the valve body <NUM> to the joining members <NUM> either. Such a connection between valve body <NUM> and joining members <NUM> can thus occur in a conventional manner by means of the connection means <NUM>, for example by means of bolts.

In other words, again, the heads <NUM> are mechanically independent of the joining members <NUM>.

In certain embodiments, such as in the embodiment depicted, each head <NUM> is entirely inserted into a respective opening <NUM>; <NUM> of the valve body <NUM>.

According to the invention, each head <NUM> is connected to the valve body <NUM> by means of a bayonet coupling <NUM>.

More in detail, each head <NUM> has an outer side wall 50a which engages an inner side wall 10b of the valve body <NUM>. Such walls are configured to obtain the bayonet coupling <NUM> between each head <NUM> and the valve body <NUM>.

In an embodiment, the head opening <NUM> is shaped so as to be engaged by a tool to lock/remove each head to/from the valve body <NUM>. For example, the head opening <NUM> is hexagonal in shape.

In an embodiment, each end of the valve body <NUM> which delimits a respective opening <NUM>; <NUM> forms a flange <NUM> for the coupling to a respective joining member <NUM>. The latter has a planar surface 30a for the coupling to the respective flange <NUM>. Such a planar surface 30a can extend radially towards the body axis Z so as to define a fluid passage gap 30b having a cross section substantially equal to that of the axial passageway <NUM> obtained in shutter <NUM>. Each head <NUM> has an outer surface 50c which is coplanar to a respective flange <NUM>. When the joining members <NUM> are fastened to the valve body <NUM>, such an outer surface 50c of each head <NUM> faces, preferably abuttingly, the planar surface 30a of the joining member <NUM>.

In an embodiment, the coupling flange <NUM> is provided by an indent <NUM> suitable to support a front sealing member <NUM>.

In an embodiment, such a front sealing member <NUM> is placed between the valve body <NUM> and the joining member <NUM>.

In an embodiment, the coupling flange <NUM> is made in one piece with the valve body <NUM>.

In an embodiment, each head <NUM> has an inner side wall 50b which forms a containment seat of a respective drawer <NUM>. In other words, each head <NUM> extends axially so as to surround a respective drawer <NUM>. In an embodiment, the inner side wall 50b slidingly guides an external side wall 54a of drawer <NUM> so as to allow possible expansions or axial movements thereof under the action of the elastic compensation member <NUM>.

In certain embodiments, each head forms a containment seat which receives drawer <NUM>, seat <NUM> and the elastic compensation member <NUM> with shape coupling, i.e., with calibrated interference, so that the head <NUM> can be inserted into and/or removed from the valve body <NUM> together with such components preassembled in the head <NUM>.

In an embodiment, each head <NUM> has a rear annular portion 50d which extends radially to act as a support surface for the elastic compensation member <NUM>.

In an embodiment, the elastic compensation member <NUM> is a Belleville spring. However, also other types of springs can be used, for example helical or spiral or leaf springs.

In an embodiment, the elastic compensation member <NUM> acts on a compression ring <NUM> which in turn axially engages drawer <NUM>.

In an embodiment, a drawer sealing ring <NUM> is interposed between compression ring <NUM> and drawer <NUM>.

In an embodiment, a head sealing ring <NUM> is interposed between each head <NUM> and the valve body <NUM>.

In an embodiment, the head sealing ring <NUM> and drawer sealing ring <NUM> are made of graphite.

In an embodiment, the elastic compensation members <NUM>, seats <NUM> and compression rings <NUM> are made of metal material. In certain embodiments, the metallic material of seat <NUM> can be in the shape of, for example tungsten carbides, chromium carbides or hard Stellite coatings.

In other embodiments, seat <NUM> can be provided by polymer material, e.g., PTFE, reinforced PTFE, modified PTFE, TFM, PCTFE KEL-F, PEEK, DEVLON or any polymer material. In this case, the maximum operating temperature of the valve is determined by the temperature resistance features of the material used for the seats.

Advantageously, the use of graphite and of the metallic materials allows the valve to be used in spaces with a working temperature up to about <NUM>° C and with operating pressures up to about <NUM> bar.

In an embodiment, valve <NUM> further comprises a shutter maneuvering stem <NUM> which extends in a rotatable manner in a respective stem seat obtained in the valve body and having a distal portion <NUM> configured to engage shutter <NUM> rotationally and a proximal portion operatively connected to a control lever <NUM>.

In an embodiment, a stem sealing member <NUM> is inserted between the distal portion <NUM> and the valve body.

In an embodiment, also the stem sealing member <NUM> is made of a material suitable to use in high temperatures such as, for example the sealing members <NUM>.

As mentioned above, the described shut-off valve <NUM> forms an independent valve unit by virtue of the presence of the heads <NUM> which retain the components in the correct position in the valve body. The present invention also relates to a valve assembly <NUM> which comprises the above-described valve <NUM> and the joining members <NUM> suitable to be removably connected to the respective ends <NUM>, <NUM> of the valve body <NUM>.

Valve <NUM> can be removed, by virtue of the heads <NUM>, from the joining members <NUM> thus leaving, for example, the latter connected to the respective ducts of a system, for example to subject valve <NUM> to maintenance or a fluid seal test.

Therefore, the present invention also relates to a method for performing a fluid seal test on valve <NUM> alone.

In order to subject valve <NUM> to the seal test, it is sufficient to connect respective system joining members (not shown) to the ends <NUM>, <NUM> of the valve body <NUM>, for example by means of connection means <NUM>, so as to connect valve <NUM> to a test system, for example a test bench.

According to an aspect of the invention, the valve <NUM> already installed in a system can be subjected to a fluid seal test or maintenance by removing it from the system but leaving the fluid inlet and outlet ducts connected to the joining members <NUM>.

Therefore, the procedure for performing the test on valve <NUM> includes here:.

In an embodiment, a possible faulty component can be replaced if the valve does not pass the seal test.

The members to be joined to the test system are then removed from the respective ends of the valve body; at least one of the heads <NUM> is removed from the valve body <NUM> so as to access the components in the valve body. At this point, the faulty component is replaced.

The valve is reassembled by reconnecting the removed head to the valve body.

At this point, the joining members can be reconnected to the test system at the ends of the valve body and the seal test can be repeated.

In order to meet specific needs, those skilled in the art could make variations to the embodiments of the above shut-off valve, valve assembly and test method, or replace elements with others which are functionally equivalent.

Claim 1:
A fluid shut-off device (<NUM>) for high temperature employments, for example in the petrochemical field, comprising:
- a valve body (<NUM>) which extends axially along a body axis (Z) between two opposite openings (<NUM>, <NUM>) for the inlet and outlet of the fluid, the valve body (<NUM>) being provided, at each end thereof delimiting a respective opening, with connection means (<NUM>) to a respective joining member (<NUM>) to be joined to a fluid inlet or outlet duct;
- a shutter (<NUM>) rotatably placed in the valve body (<NUM>) between the two inlet/outlet openings (<NUM>, <NUM>), the shutter (<NUM>) being crossed by an axial passageway (<NUM>) suitable to put the two opposite openings (<NUM>, <NUM>) into fluid communication and being rotatable between a closed position, in which it prevents the passage of the fluid from one opening to the other opening of the valve body (<NUM>), and an open position, in which it allows the passage of the fluid between the two openings of the valve body (<NUM>);
- two shutter seats (<NUM>) which rotatably support the shutter (<NUM>), wherein each shutter seat (<NUM>) is supported by or is integral with a respective drawer (<NUM>);
wherein each drawer (<NUM>) is elastically affected by a respective elastic compensation member (<NUM>) which applies to the drawer (<NUM>) a compensation pressure directed towards the shutter (<NUM>),
and wherein a head (<NUM>) is inserted, with shape and/or force coupling, into each of the inlet/outlet openings (<NUM>, <NUM>) of the valve body (<NUM>), the head defining an axial abutment for a respective elastic compensation member (<NUM>), wherein each head (<NUM>) has an outer side wall (50a) which sealingly engages an inner side wall (10b) of the valve body (<NUM>), is axially crossed by a head opening (<NUM>) for the passage of the fluid, and is inserted into the respective opening without engaging said connection means (<NUM>) with the joining member (<NUM>),
characterized in that the outer wall (50a) of the head and the inner side wall (10b) of the valve body (<NUM>) are connected to each other by means of bayonet coupling (<NUM>).