*** ** DESCRIPTION The present invention concerns a fluid flow cut-off valve, particularly for pipe fittings destined to the transport of oil and chemical fluids.

By the term"fitting"a connector for flanges capable to connect easily and to disconnect in a secure and quick way the same flanges, both in normal conditions as well as in safety conditions, is meant.

There are known pipe fittings that are used in order to connect to each other in a quickly separable way pipes destined to the transport of fluid oil products, in particular from one ship to land and viceversa, or from an extraction platform to a ship or from ship to ship or from ship or platform to extraction wells at sea bottom and so on. One of these is described for examlple in EP-A-0153773 md it comprises two fitting parts attachable to respective pipes and quick-coupling and quick-release means suitable to connect the two fitting parts with each other. Each one of these is provided with a respective cut-off valve, that has the duty to interrupt the flow of the fluid, in particular just before the uncoupling of the fitting.

The known cut-off valves comprise a body with spherical shape with passing through cylindrical duct. Their fluid-tightness when in closing position is assured by packings supported by mobile seats that are elastically biased and placed upstream of the valve in the direction of the flow of the fluid. Due to the effect of their progressive wear, and also because of the difficult servicing conditions in which said fittings operate, it is possible that the water-tightness of the packings deteriorates with consequent possible leaks of fluid. If this happens, with uncoupled fitting, for the valve of the fitting part closer to the source of the fluid flow, this determines the waste of product and with it considerable environmental and economic damages.

In order to obviate such inconvenience it is often provided to insert in

the pipe upstream, where there is fluid in pressure, two valves in sequence.

With this the risk of a leakage is decreased, but with greater volume and costs.

In view of this state of the art, object of the present invention is to provide a cut-off valve that, without requiring the addition of a second valve, allows the fitting to work always in safety conditions.

According to the invention such object is attained with a cut-off valve comprising a spherical body passed through by a diametral duct and a first water-tightness packing placed upstream of said spherical body in the direction of the flow of fluid and elastically maintained against said spherical body, characterised in that it has a second water-tightness packing placed downstream of said spherical body and elastically maintained against it.

A valve of this kind placed in the fitting part which is closer to the fluid source evidently assures the interception of the fluid also in the case in which the packing upstream decreases its water-tightness. In short, a degree of guarantee against leakage is thus obtained that is comparable to the one offered by two valves arranged one after the other, but with the volumes and the weights of a single valve.

These and other characteristics of the present invention will be made more evident from the following detailed description of an embodiment thereof that is described as a non limiting example in the enclosed drawings, in which: Figure 1 shows a longitudinal section of a pipe fitting with cut-off valves closed; Figure 2 shows in magnified scale a detail of Figure 1 ; Figure 3 shows a longitudinal section of a pipe fitting with open cut-off valves.

In Figures 1 and 3 a fitting 1 is shown that is made up of two parts 14- 15, each one of which comprises a body 16 passed through by a channel 24

and a flange 19 drawn near frontally and kept coupled to the corresponding flange 19 of the other fitting part by quick-coupling and quick-release means, not shown and known per se, as for example from EP-A-0153773.

To each body 16 a corresponding end 20 of one of the two pipes 21 coupled to each other by the fitting 1 is fastened by means of screws.

The flow of fluid through the channels 24 of the two fitting parts is controlled by cut-off valves 17-18, one for each fitting part, which are made up of a spherical body 3, with a passing through cylindrical duct 4, revolvable around a barycentric transversal axis by means of a driving shaft 5 integral with it, held in position by opportune fastening systems. The valve 17 precedes valve 18 in the direction of flow of the fluid (arrow F in Figure 3). The shafts 5 of the two valves 17 and 18 are connected with each other by means known per se and not shown, that make the opening and closing movements of the two valves synchronous.

The valve 17 (Figure 2) and the valve 18 have upstream of the spherical bodies 3 respective annular packings 6 supported by mobile seats 7 and held in position by threaded ring nuts 12. The mobile seats 7 are inserted in sliding way into the respective bodies 16 and they are biased to maintain the respective packings 6 against the spherical bodies 3 by Belleville washers 9 placed around hinges 10 inserted in cavities 29 of the respective bodies 16 and supported by threaded ring nuts 11 screwed onto the mobile seats 7. O- Rings 13 provide the water-tightness between said mobile seats 7 and the bodies 16.

The valve 17 (Figure 2) has in addition downstream of the spherical body 3 an additional annular packing 30 supported by a mobile seat 31 and held in position by a threaded ring nut 32. The mobile seat 31 is inserted in sliding way into the body 16 and is biased to maintain the packing 30 against the spherical body 3 by Belleville washers 33 placed around hinges 34 inserted in cavities 36 of the body 16 and supported by a threaded ring nut 37 that is screwed onto the mobile seat 31.

During the operation, the fluid, coming from the pipe 21 situated on the right in Figures 1 and 3, enters the nearby channel 24 and meets the cut-off valve 17. If this is in opening position (Figure 3), said fluid continues its flow through the cylindrical duct 4 in order to get then into the fitting part 14. Since the synchronised valves 17-18 are two, the valve 18 will be in opening position too thus allowing the passage of the fluid that finally exits from the fitting 1 and goes into the pipe 21 situated on the left in Figures 1 and 3.

If the valve 17 is closed (Figures 1 and 2), the fluid in pression thrusts the mobile seat 7 in the direction of flow of the same fluid and, helped by the washers 9, causes the packing 6 to tighten against the spherical body 3, withholding the fluid upstream of valve. If because of wear or of difficult operating conditions, there are leakages between the packing 6 and the spherical body 3 with consequent flooding of the chamber 35, the fluid is besides withheld by the second packing 30 that is thrust in turn in watertight conditions against the spherical body 3 by the same fluid and by the washers 33. A greater reliability of the fitting is therefore assured.