The present invention regards essentially an improvement in the flexible composite hoses, that are used mainly for transportation of fluids in the field of chemical and/or petrochemical industry, and in the sectors of services and transportation.

As known, a flexible composite hose comprises a cylindrical multi-layered surface, composed of some layers made of different materials, situated between an inner reinforcement spiral and an outer reinforcement spiral, so that the inner and outer spirals express some opposing forces that maintain a robust general structure of the hose.

Nowadays, the reinforcement spiral are composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section shaped as a circle. Therefore, the different layers that compose the hose are kept together just by the mechanical action of the two spirals, because the layers are not glued neither vulcanised each other. That leads to a significant advantage to achieve hoses having a high level of flexibility, even for large diameters, and to the high versatility of possibility to use different materials for the inner components.

However, with reference to hoses having a large diameter (higher than 100 mm), a hard technical problem has been observed, represented by the collapse of the inner spiral, especially due to the intense use, to the frequent movements and to the curving angles necessary during the field operations.

What happens indeed is that a translation of the inner spiral occurs, in respect to the longitudinal axis, and due to causes that are not easily detectable in a following assessment and study. More exactly, the inner spiral is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section shaped as a circle. Therefore, it tends to "slide”, moving from it initial position up to a point where the mechanical forces of the inner and outer spirals are no more opposed each other, and then the hoses collapses as a consequence.

When that happens, all the wire composing the inner spiral moves, and the layers belonging to the multi-layered surface accumulate each other, up to the closure of the inner passage, making the flexible hose completely out of order.

The above hard problem is solved by the present invention, that has as a main objective to achieve a flexible composite hose for transportation of fluids, in the field of chemical and/or petrochemical industry, having an inner reinforcement spiral and an outer reinforcement spiral, where the general structure of the hose is kept robust and compact, even for hoses having a large diameter, in front of intense external forces, narrow curving angles, and a use in the long term.

Another objective is that the inner wall hose presents a surface that would be as smooth as possible, having few protrusions, achieving an optimal passage of fluids characterised by a high speed of transfer, minimizing the pressure drop caused by friction, turbulence, partial occlusions and/or other fluid-dynamic effects.

Another further objective is that, even with the inner wall hose presenting a surface as smooth as possible, and having few protrusions, it could result to be not perfectly flat, so that to minimize the contact area with a mandrel, during the factory production process, and therefore to maintain a minimal friction that facilitates the longitudinal removal of said hose from the same mandrel.

Another further objective is that the composite tube continues to have a simple structure as well as in the prior art, that means to be composed by few essential components, in order to be produced on a large industrial scale, by a production process that would be economically sustainable, competitive on the market, technically efficient, and using materials that are common and easy to find.

Therefore, it is specific subject of the present invention a flexible composite hose, for transportation of fluids in the field of chemical and/or petrochemical industry, comprising:

- a cylindrical multi-layered surface, composed of some layers made of different materials, situated between an inner reinforcement spiral and an outer reinforcement spiral, so that the inner and outer spirals express some opposing forces that maintain a robust general structure of the hose, characterized in that:

- said inner reinforcement spiral is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section having a shape that approximates the shape of a polygon, more exactly it has a shape of a polygon in which: all the vertexes are rounded, and at least one side is curved with a concavity directed outside;

- said cross-section approximating a polygon presents said curved side placed aligned to the inner wall of the hose, and the opposite vertex placed as a cusp into the inner side of said cylindrical multi-layered surface, all along the length of the hose, so that three effects are achieved: the first is that said inner spiral is anchored more effectively to said cylindrical multi-layered surface, avoiding therefore any sliding motion, and increasing strength and robustness of the general structure of the hose, even for large diameters; the second is to achieve an inner wall of the hose as smooth as possible, permitting therefore an optimal passage of fluids inside, resulting in a higher speed of transfer; the third is to maintain, all during the factory production process, a minimal contact surface between said hose and a mandrel on which it is constructed, and to facilitate therefore, at the end of said process, the longitudinal removal of said hose from the mandrel, maintaining at the same time a minimal friction.

The present invention will now be described for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to figures of the enclosed drawings, wherein:

Figure 1 is a perspective view of a partially sectioned end belonging to a composite hose, according to the prior art, where the main components are shown, and they are represented by a cylindrical lateral wall situated between an inner reinforcement spiral and an outer reinforcement spiral;

Figure 2 is a perspective view of a particular belonging to an improved composite hose, according to the present invention, where the inner and outer reinforcement spirals have a triangular cross-section;

Figure 3 is a lateral view of a particular belonging to the same improved composite hose of Figure 2, where said triangular cross-section of the inner and outer reinforcement spirals is better visualized;

Figure 4 is a lateral view of the same improved composite hose of Figure 2, as a whole and having respective connection elements on its ends;

Figure 5 is a front view of the same improved composite hose of Figure 4, visualized at one of its ends;

Figure 6 is a perspective view of the same improved composite hose of Figures 4 and 5, where its outer reinforcement spiral is better visualized;

Figure 7 is a front view of a first possible cross-section of one of the reinforcement spirals, that approximates the shape of a triangle, where all the vertexes are rounded, and at least one side is curved with a concavity directed outside;

Figure 8 is a front view of a first possible cross-section of one of the reinforcement spirals, that approximates the shape of a triangle, where all the vertexes are rounded, and all the sides are curved with a concavity directed outside; Figure 9 is a perspective view of a tract of the same hose of Figure 2, where its main components are better shown, composed of a cylindrical lateral wall situated between an inner reinforcement spiral and an outer reinforcement spiral;

Figure 10 is a perspective view in detail of the same tract of hose of Figure 2, where the cross-sections of said inner and outer reinforcement spirals, that approximate the shape of a triangle, are better visualized;

Figure 11 is a perspective view in detail of the same tract of hose of Figure 2, where the cross-sections of said inner and outer reinforcement spirals, that approximate the shape of a triangle, are further visualized;

Figure 12 is a schematic view of the flow lines related to a fluid that flows inside a composite tube, in condition of a laminar motion, with an obstacle represented by a transversal element having a circular cross-section;

Figure 13 is a schematic view of the flow lines related to a fluid that flows inside a composite tube, in condition of a transition from a laminar motion to a turbulent motion, with the same obstacle of Figure 12;

Figure 14 is a schematic view of the flow lines related to a fluid that flows inside a composite tube, in condition of a turbulent motion, with the same obstacle of Figure 12.

It is here underlined that only few of the many conceivable embodiments of the present invention are described, which are just some specific non-limiting examples, having the possibility to describe many other embodiments based on the disclosed technical solutions of the present invention.

Figure 1 shows a partially sectioned end belonging to a flexible composite hose 200, for transportation of fluids in the field of chemical and/or petrochemical industry, according to the prior art, where the main components are shown, and they are represented by a cylindrical multi-layered surface 206, composed in turn of some layers made of different materials, situated between an inner reinforcement spiral 204 and an outer reinforcement spiral 203, so that the inner and outer spirals 204, 203 express some opposing forces that maintain a robust general structure of the hose 200.

Either the inner reinforcement spiral 204 and the outer reinforcement spiral 203 are composed of a metallic wire, that is helically wrapped around, where the same metallic wire has respective cross-sections 208, 207 having the shape of a circle.

Instead, Figures 4, 5, 6 and 9, 10, 11 show a flexible composite hose 100, for transportation of fluids in the field of chemical and/or petrochemical industry, according to the present invention.

The main components, shown in details in Figures 2 and 3, are represented by a cylindrical multi-layered surface 106, composed in turn of some layers made of different materials, situated between an inner reinforcement spiral 104 and an outer reinforcement spiral 103, so that the inner and outer spirals 104, 103 express some opposing forces that maintain a robust general structure of the hose 100.

According to a first embodiment of the present invention, said inner reinforcement spiral 104 is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section 108 having a shape that approximates the shape of a polygon 210.

More exactly it has a shape of a polygon 210, as that shown in Figure 7, in which: all the vertexes are rounded, and at least one side is curved with a concavity directed outside.

Said cross-section 108 approximating a polygon 210 presents said curved side 212b placed aligned to the inner wall of the hose 100, and the opposite vertex 211a placed as a cusp into the inner side of said cylindrical multi-layered surface 106, all along the length of the hose 100.

In such a way, three effects are achieved. The first is that said inner spiral 104 is anchored more effectively to said cylindrical multi-layered surface 106, avoiding therefore any sliding motion, and increasing strength and robustness of the general structure of the hose 100, even for large diameters. The second is to achieve an inner wall of the hose 100 as smooth as possible, permitting therefore an optimal passage of fluids inside, resulting in a higher speed of transfer. The third is to maintain, all during the factory production process, a minimal contact surface between said hose 100 and a mandrel on which it is constructed, and to facilitate therefore, at the end of said process, the longitudinal removal of said hose 100 from the mandrel, maintaining at the same time a minimal friction.

According to a second embodiment of the present invention, said outer reinforcement spiral 103 is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section 107 having a shape that also approximates the shape of a polygon 210.

More exactly it has a shape of a polygon 210, as that shown in Figure 7, in which: all the vertexes are rounded, and at least one side is curved with a concavity directed outside.

Said cross-section 107 approximating a polygon 210 presents said curved side 212b placed aligned to the inner wall of the hose 100, and the opposite vertex 211a placed as a cusp into the inner side of said cylindrical multi-layered surface 106, all along the length of the hose 100.

In such a way, an effect is achieved that said outer spiral 103 is anchored more effectively to said cylindrical multi-layered surface 106, avoiding therefore any sliding motion, and increasing strength and robustness of the general structure of the hose 100, even for large diameters.

According to a third embodiment of the present invention, said inner reinforcement spiral 104 is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section 108 having a shape that approximates the shape of a polygon 220.

More exactly it has a shape of a polygon 220, as that shown in Figure 8, in which: all the vertexes are rounded, and all the sides are curved with a concavity directed outside.

Said cross-section 108 approximating a polygon 220 presents one of said curved sides, 222a or 222b or 222c, placed aligned to the inner wall of the hose 100, and the opposite vertex, 222c or 222a or 222b, placed as a cusp into the inner side of said cylindrical multi-layered surface 106, all along the length of the hose 100.

In such a way, it is achieved, in addition to the three previous effects, the additional effect that said inner spiral 104 is anchored more effectively to said cylindrical multi layered surface 106, because the contact surfaces of curved sides 222a, 222b embed into the multi-layer 106 and adapt the tissues to the profile.

According to a fourth embodiment of the present invention, said outer reinforcement spiral 103 is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section 107 having a shape that also approximates the shape of a polygon 220.

More exactly it has a shape of a polygon 220, as that shown in Figure 8, in which: all the vertexes are rounded, and all the sides are curved with a concavity directed outside.

Said cross-section 107 approximating a polygon 210 presents one of said curved sides, 222a or 222b or 222c, placed aligned to the inner wall of the hose 100, and the opposite vertex, 222c or 222a or 222b, placed as a cusp into the inner side of said cylindrical multi-layered surface 106, all along the length of the hose 100.

In such a way, it is achieved, in addition to the three previous effects, the following additional two effects. The first that said outer spiral 103 is anchored more effectively to said cylindrical multi-layered surface 106, because the contact surfaces of curved sides 222a, 222b embed into the multi-layer 106 and adapt the tissues to the profile. The second is to facilitate, during the factory production process, the application of the metallic wire on a mandrel, in order to achieve, first the inner spiral 104, and then the outer spiral 103 of the composite hose 100. In fact, according to the fact that all the sides 222a, 222b are equal, there is not a preferred side on the wire to be addressed to the same mandrel, and furthermore it is minimized the angle of rotation of the same wire, in the passage from the production of the inner wire 104 to the outer wire 103, by using the same wire.

According to the principles of the present invention, said polygon 210 or 220, whose shape is approximated by the cross-section 108 of said reinforcement wire, that composes said inner reinforcement spiral 104, can be represented by: a triangle, or a square, or a pentagon, or a hexagon, etc., and in the same way, said polygon 210 or 220, whose shape is approximated by the cross-section 107 of said reinforcement wire, that composes said outer reinforcement spiral 103, can be represented by: a triangle, or a square, or a pentagon, or a hexagon, etc.

In the flexible composite hose 100, said cylindrical multi-layered surface 106 can be composed of layers made of different types of materials, as in example: polypropylene, polyethylene, polyester, PTFE, etc.

In such a way, the composite hose 100 results to have a wide range of applications, in conditions of different pressures and temperatures, and being compatible and usable for the passage of various types of chemical products, having different chemical- physical characteristics.

As above described, the effect of the present invention to achieve an inner surface of hose 100 as smooth as possible, causes an optimal passage of fluids inside, and therefore a high speed of transfer.

This fact arises from study of turbulence phenomena that are observed when there are obstacles or quick variation of shape in the hose 100 where the fluid flows inside. In fact, deformation in flow lines, induced by obstacle, are propagated by the fluid viscosity, with a possible generation of vortexes.

Figures 12, 13 and 14, show the flow in a hose, around a circle having diameter D, placed with the axis that is normal to the figure, in three different flow situations. The same circle represents exactly the inner reinforcement wire having a round shape, for the production of composite hoses according to the prior art. The reinforcement wire emerges by half size of its diameter into the hose. The number of Reynolds represents the ratio between inertial effects and viscous effects.

With reference to low values of flow 250 (Figure 12) the viscosity prevails: the presence of obstacle 253 affects the current lines 252 in a wide region 251 , in respect to diameter D, in any directions in respect to the flow.

By increasing the flow 260 (Figure 13), the region 261 preceding the cylinder affected by the viscous distortion of flow lines 262 decreases: the effects of the presence of obstacle 263 are moved down and the flow loses its symmetry. Another consequence of the influence of the inertial effects is represented by the fluid layer in contact with the object.

In a condition of flow 270 (Figure 14) characterized by very high Reynolds numbers, the region 275 affected by the presence of the obstacle 272 is located quite completely behind it, having a very long wake region, irregular, unstable, and highly characterized by turbulence.

The turbulence slows down significantly the flow inside the hose, leading to the induced effect to decrease the fluid capacity. That increases the time of load/unload operations in tankers or tank ships, even considering that for security reasons it is not possible to increase pressures during operations.

For this reason, by changing the geometry of cross-section in the inner wire, from rounded to polygonal or near-triangular, according to principles of the present invention, it is achieved the result to avoid quite totally any obstacle inside the hose, keeping a situation of laminar motion in the fluid flow instead of a situation of turbulent motion.

Therefore, the above examples show that the present invention reaches all the expected objectives. In particular, it permits to achieve a flexible composite hose for transportation of fluids, in the field of chemical and/or petrochemical industry, having an inner reinforcement spiral and an outer reinforcement spiral, where the general structure of the hose is kept robust and compact, even for hoses having a large diameter, in front of intense external forces, narrow curving angles, and a use in the long term.

Furthermore, the invention allows that the inner wall hose presents a surface that is as smooth as possible, having few protrusions, achieving an optimal passage of fluids characterised by a high speed of transfer, minimizing the pressure drop caused by friction, turbulence, partial occlusions and/or other fluid-dynamic effects.

Further according to the invention, even said inner wall hose presenting a surface as smooth as possible, and having few protrusions, it results to be not perfectly flat, so that to minimize the contact area with a mandrel, during the factory production process, and therefore to maintain a minimal friction that facilitates the longitudinal removal of said hose from the same mandrel.

Finally according to the invention, the composite tube continues to have a simple structure as well as in the prior art, that means that is composed by few essential components, in order to be produced on a large industrial scale, by a production process that is economically sustainable, competitive on the market, technically efficient, and using materials that are common and easy to find.

The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is clear that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope, as defined in the enclosed claims.