Patent Description:
The document <CIT> shows a helical stacked composite hose comprising a helical body being a helical long strip; each cross section of the helical body having a flat portion facing toward a center of the helical body; an inner cloth enclosing the helical body; an inner surface of the inner cloth having a flat cambered shape; a plurality of thin film layers enclosing the inner cloth; an outer cloth winding around the film layers so as to form as a round cylinder layer; an outer helical spring being installed around the outer cloth; a rubber cover being formed with a recess; the inner cloth, film layers, outer cloth being embedded into the recess; a ferrule enclosing the outer surface of the rubber cover and the outer cloth; a joint having a stepped outer layer. A cross section of the strip of the helical body is a triangular, pentagon and semi-round.

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 <NUM>), 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:.

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:.

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.

<FIG> shows a partially sectioned end belonging to a flexible composite hose <NUM>, 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 <NUM>, composed in turn of some layers made of different materials, situated between an inner reinforcement spiral <NUM> and an outer reinforcement spiral <NUM>, so that the inner and outer spirals <NUM>, <NUM> express some opposing forces that maintain a robust general structure of the hose <NUM>.

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

Instead, <FIG>, <FIG> and <FIG><FIG>show a flexible composite hose <NUM>, 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 <FIG>, are represented by a cylindrical multi-layered surface <NUM>, composed in turn of some layers made of different materials, situated between an inner reinforcement spiral <NUM> and an outer reinforcement spiral <NUM>, so that the inner and outer spirals <NUM>, <NUM> express some opposing forces that maintain a robust general structure of the hose <NUM>.

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

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

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

In such a way, three effects are achieved. The first is that said inner spiral <NUM> is anchored more effectively to said cylindrical multi-layered surface <NUM>, avoiding therefore any sliding motion, and increasing strength and robustness of the general structure of the hose <NUM>, even for large diameters. The second is to achieve an inner wall of the hose <NUM> 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 <NUM> and a mandrel on which it is constructed, and to facilitate therefore, at the end of said process, the longitudinal removal of said hose <NUM> from the mandrel, maintaining at the same time a minimal friction.

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

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

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

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

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

Said cross-section <NUM> approximating a polygon <NUM> presents one of said curved sides, 222a or 222b or 222c, placed aligned to the inner wall of the hose <NUM>, and the opposite vertex, 221c, 221a or 221b placed as a cusp into the inner side of said cylindrical multi-layered surface <NUM>, all along the length of the hose <NUM>.

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

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

Said cross-section <NUM> approximating a polygon <NUM> presents one of said curved sides, 222a or 222b or 222c, placed aligned to the inner wall of the hose <NUM>, and the opposite vertex, 221c, 221a or 221b placed as a cusp into the outer side of said cylindrical multi-layered surface <NUM>, all along the length of the hose <NUM>.

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 <NUM> is anchored more effectively to said cylindrical multi-layered surface <NUM>, because the contact surfaces of curved sides 222a, 222b embed into the multi-layer <NUM> 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 <NUM>, and then the outer spiral <NUM> of the composite hose <NUM>. 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 <NUM> to the outer wire <NUM>, by using the same wire.

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

In the flexible composite hose <NUM>, said cylindrical multi-layered surface <NUM> 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 <NUM> 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 <NUM> 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 <NUM> 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.

<FIG>, 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 <NUM> (<FIG>) the viscosity prevails: the presence of obstacle <NUM> affects the current lines <NUM> in a wide region <NUM>, in respect to diameter D, in any directions in respect to the flow.

By increasing the flow <NUM> (<FIG>), the region <NUM> preceding the cylinder affected by the viscous distortion of flow lines <NUM> decreases: the effects of the presence of obstacle <NUM> 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 <NUM> (<FIG>) characterized by very high Reynolds numbers, the region <NUM> affected by the presence of the obstacle <NUM> 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.

Claim 1:
A flexible composite hose (<NUM>), for transportation of fluids in the field of chemical and/or petrochemical industry, comprising:
- a cylindrical multi-layered surface (<NUM>), composed of some layers made of different materials, situated between an inner reinforcement spiral (<NUM>) and an outer reinforcement spiral (<NUM>), so that the inner and outer spirals (<NUM>, <NUM>) express some opposing forces that maintain a robust general structure of the hose (<NUM>),
characterized in that:
- said inner reinforcement spiral (<NUM>) is composed of a metallic wire, that is helically wrapped around, where the same metallic wire has a cross-section (<NUM>) having a shape that approximates the shape of a polygon (<NUM>), more exactly it has a shape of a polygon (<NUM>) in which: all the vertexes are rounded, and at least one side is curved with a concavity directed outside;
- said cross-section (<NUM>) approximating a polygon (<NUM>) presents said curved side (212b) placed aligned to the inner wall of the hose (<NUM>), and the opposite vertex (211a) placed as a cusp into the inner side of said cylindrical multi-layered surface (<NUM>), all along the length of the hose (<NUM>),
so that three effects are achieved: the first is that said inner spiral (<NUM>) is anchored more effectively to said cylindrical multi-layered surface (<NUM>), avoiding therefore any sliding motion, and increasing strength and robustness of the general structure of the hose (<NUM>), even for large diameters; the second is to achieve an inner wall of the hose (<NUM>) 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 (<NUM>) and a mandrel on which it is constructed, and to facilitate therefore, at the end of said process, the longitudinal removal of said hose (<NUM>) from the mandrel, maintaining at the same time a minimal friction.