Cross-Reference to Related Applications

This Patent Application claims priority from European Patent Application No . 21217850 . 3 filed on December 27 , 2021 , the entire disclosure of which is incorporated herein by reference .

Technical Field

This invention regards a duct and a related production method .

Background

In particular, the duct could be used in a civic water-supply system and be traversed by water or it could be intended to convey a f luid for industrial use .

The known ducts comprise multiple pipes connected together via welded j oints , interception elements , or connection j oints .

More speci fically, the duct has multiple points anchoring it to the ground and the pipes may be fitted inside the interception elements and connection j oints .

The flow of fluid inside the duct and the pressure inside the duct itsel f determine an axial force on the components/ j oints downstream and upstream of the pipe and on the pipe itself with reference to a forward direction of the fluid . This axial thrust is generated, for example , where there are curved sections of the duct or when the interception elements are being closed .

As a result , the pipe tends to slide out of the interception elements or the connection j oints .

According to some known solutions , the pipe is axially fixed to the interception elements or to the connection j oints using adhesive substances .

In the sector, there is a need to limit , as much as possible , the risk of slipping out by using adhesives as little as possible .

This need is particular felt in the case of repairs to already existing ducts having a broken area, according to a technology known as Cured- In-Place-Pipe ( CIPP ) .

According to this technology, a tubular element ( also known as a liner ) made of polyester felt or glass fibre is preliminarily imbued with a thermosetting resin ( called a carrier ) - polyester, vinyl ester, or epoxy resin - suitable for resisting the chemical action of fluids conveyed in the duct , and, following this , inserted inside the pipe to be repaired, which assumes the function of host pipe .

The sheath is then inflated inside the host pipe , so as to bear it perfectly in contact with the walls of the pipe itsel f .

Once inserted and inflated, the tubular element imbued with resin is made to harden through the curing/polymeri zation of the resin with which it is imbued, until it adheres to the host pipe to be repaired .

In particular, polymeri zation of the resin may occur thanks to the administration of heat using hot water or superheated steam or radiant energy via ultraviolet ray emitters .

When the consolidation is finished, the hardened sheath is cut at intermediate and end inspection wells .

The end contact points between the sheath and host pipe are sealed via the manual application of special chemically binding putties or by using speci fic seals .

KR-A-2019/ 0142885 discloses a duct according to the preamble of claim 1 and a method for producing a duct according to the preamble of claim 10 .

Summary

The purpose of this invention is to produce a duct , which meets , easily and economically, at least one of the needs described above .

The above-mentioned purpose is achieved with a duct according to what is claimed in claim 1 .

This invention also relates to a method for producing a duct according to what is claimed in claim 10 .

Brief Description of the Drawings

To better understand this invention, a preferred embodiment is described below, by way of non-limiting example and with reference to the attached drawings , in which :

- Figure 1 illustrates , in a partial cross-section view, a duct produced according to the precepts of this invention, with parts removed for clarity;

- Figure 2 illustrates - in an exploded perspective view and on a greatly enlarged scale - some components of the duct in Figure 1 ;

- Figure 3 is a perspective view on an enlarged scale of a conveyor pipe of the duct in Figures 1 and 2 ;

- Figure 4 is a perspective view on an enlarged scale of a flanged element of the duct in Figures 1 and 2 ;

- Figures 5 to 8 illustrate respective steps of a method for repairing a duct produced according to the precepts of this invention ;

- Figure 9 is a longitudinal cross-section view of the duct in Figure 8 ; and

- Figures 10 and 11 illustrate , on a greatly enlarged scale , some details of the duct in Figures 8 and 9 .

Description of Embodiments

With reference to the figures attached, the reference number 1 indicates a duct for conveying a pressurised fluid .

The pressurised fluid may be for civic or industrial use .

The duct 1 comprises multiple conveyor pipes 3 for conveying fluid connected together in a fluid-tight manner, only one of which is illustrated in Figure 1 .

Each pipe 3 extends along its own axis A.

With reference to Figure 3 , the duct 2 comprises , in addition, for each pipe 3 : a pair of flanged elements 4 coaxially and externally fitted to respective opposite axial ends 5 of the pipe 3 ; a pair of connection elements 6 connected to respective flanged elements 4 and, directly or indirectly, to respective pipes 3 not illustrated in Figure 3 ; and a pair of disc-shaped seals 7 axially placed between respective flanged elements 4 and corresponding connection elements 6 .

Hereinafter in this description, only one pipe 3 i s described and the corresponding flanged elements 4 , connection elements 6 , and seals 7 , since the pipes 3 are identical to each other .

In particular, the duct 2 is fixed in a known way to the ground at multiple anchorage points not illustrated in the attached figures .

The flanged elements 4 also comprise : - corresponding, radially external surfaces 13 ; and corresponding, radially internal surfaces 11 , opposite to the first surfaces 13 and coupled, in contact , with the respective surfaces 12 of the pipe 3 .

In the example illustrated in Figures 1 and 2 , the surfaces 13 are flat .

The surfaces 12 define respective ends 5 of the pipe 3 .

The surfaces 11 and 12 comprise respective corrugations 15 , 16 coupled together so as to axially hold the pipe 3 inside the flanged elements 4 ; the corrugations 15 , 16 have greater extensions parallel to the axis A and a thickness radial to the axis A and smaller than the extension along the axis A itsel f .

The term "corrugation" refers , hereinafter in this description, to a succession that is continuous , or continuous in sections , and periodic of annular ridges and groves around the axis A.

The corrugation has , in one section containing the axis A:

- a longitudinal extension direction along which the ridges and grooves repeat periodically; and

- a transverse direction orthogonal to the extension direction and along which the ridges and grooves extend at a distance from each other . The corrugations 15 , 16 are preferably coupled without the use of adhesive .

The coupling between the corrugations 15 , 16 generates an axial reaction on the pipe 3 that counters the dynamic action axially exerted by the fluid in the pipe 3 . This action is exerted, for example , by the dynamic conditions or by the static pressure of the fluid .

By way of non- limiting example , this action is generated at curved sections of the pipe 3 or during closure of the valves arranged downstream of the pipe 3 itsel f with reference to the forward direction of the fluid .

Hereinafter in this description, only one corrugation 15 is described, since the other corrugation 16 is identical to the first corrugation 15 .

More speci fically, the corrugation 15 comprises multiple repeated modules 20 , identical to each other and arranged consecutively parallel to the axis A.

Each module 20 extends coaxially to the axis A and comprises , in particular, proceeding parallel to the axis A in a direction oriented by one of the flanged elements 4 towards the other flanged element 4 ( Figures 2 , 10 , and 11 ) :

- a truncated cone section 39 ;

- a cylindrical section 40 arranged at a first radial distance from the axis A;

- a truncated cone section 41 ; and

- a cylindrical section 42 arranged at a second radial distance from the axis A that is greater than the first radial distance .

The section 39 is connected to the section 40 of the corresponding module 20 and to the section 42 of a module 20 adj acent to it via a pair of pipe fittings with the radius r .

The section 41 is connected to the sections 40 , 42 via a pair of pipe fittings with the radius r .

In particular, the axial extension of the sections 40 , 42 is equal .

The sections 42 , 40 respectively define ridges and grooves of the respective corrugations 15 , 16 .

The extension parallel to the axis A of the sections 39 , 41 is equal and greater than the axial extension of the sections 40 , 42 .

The sections 39 , 41 have respective disposition planes P, Q tilted between them at the same acute angle a in relation to the axis A.

The sections 39 , 41 are symmetrical in relation to a radial median plane of the section 40 of the same module 20 .

The duct 1 comprises , in addition, multiple annular seals 70 of axis A placed axially between respective ends 5 of the pipe 3 and corrugations 15 of corresponding flanged elements 4 so as to prevent fluid from accessing the area between the above-mentioned ends 5 and the respective corrugations 15 .

To this end, the corrugations 16 are axially shorter than the corresponding corrugations 15 and end at an axial distance from the above-mentioned corrugations 16 so as to enable the fixing of the corresponding seals 70 .

Each connection element 6 is , in the example illustrated, shaped like a tubular body bolted, at corresponding head surfaces 8 of opposite axial ends , to the flanged elements 4 of corresponding pipes 3 .

Each seal 7 is axially placed in contact between one corresponding flanged element 4 and a related connection element 5 .

Each flanged element 4 comprises , in the example illustrated, a pair of hal f-bearings 9 bolted to each other ( Figure 2 ) .

With reference to the embodiment illustrated in Figures 5 to 8 , the pipe 3 is housed in a fluid-tight manner inside a host pipe 50 having a broken area 51 .

In this way, the pipe 3 implements a technology known as cured-in-place-pipe .

In particular, the pipe 3 is shaped starting from a tubular closed sheath 52 preliminarily imbued with a thermosetting resin ( called a carrier ) - polyester, vinyl ester, or epoxy resin - suitable for resisting the chemical action of the fluids conveyed in the duct , and, following this , inserted inside the host pipe 50 ( Figure 5 ) .

The sheath 52 is then inflated inside the host pipe 50 so as to make it adhere perfectly to the walls of the host pipe 50 itself ( Figure 6 ) .

Once inserted and inflated, the sheath 52 imbued with resin is made to harden through the curing (polymeri zation) of the resin with which it is imbued, until it forms the pipe 3 adhering to the pipe 50 to be repaired at the area 51 ( Figure 7 ) .

When the consolidation is finished, the hardened sheath 52 is cut at the ends 5, or intermediate inspection wells that are not illustrated .

In particular, polymeri zation of the resin may occur thanks to the administration of heat using hot water or superheated steam or radiant energy via ultraviolet ray emitters .

When the pipe 3 is intended to be inserted in the host pipe 50 , the section 42 of each module 20 and the flanged elements 4 comprise respective multiple radial holes 49 , which are through holes and angularly spaced equally around the axis A. The holes 49 are designed to enable the escape of the gas that is produced during the hot polymerization of the sheath 52, and normally trapped between the fibres of the sheath 52, or to enable the evacuation of air that, during the step in which the sheath 52 approaches the surface 15, would remain trapped, preventing the correct coupling of the surfaces 15, 16.

In the example illustrated, the pipe 3 is a made of glass fibre or polyester felt.

The flanged element 4 is, in addition, with reference to the example illustrated, produced as a single body made via melting or mechanical sintering techniques (Figure 3) .

The assembly and operation of the duct 1 is described below in relation to just one pipe 3.

During the assembly of a new duct 1 or repair of the duct 1 itself, the ends 5 of the pipe 3 are housed in the open half-bearings 9 of the corresponding flanged elements 4. Following this, the half-bearings 9 are closed so as to precisely couple the corrugations 15, 16 and solidly fix the pipe 3 to the corresponding flanged elements 4. The flanged elements 4 with the closed halfbearings 9 bolted together are, at this point, fixed to the ground.

When repairing the host pipe 50, according to the technology known as cured-m-place-pipe , the sheath 52 is housed inside the host pipe 50 at the broken area 51 and the flanged elements 4 are connected to corresponding, opposite axial ends of the host pipe 50 ( Figure 5 ) .

The sheath 52 is then inflated inside the host pipe 50 so as to make it adhere perfectly to the walls of the host pipe 50 itsel f . The radial holes 49 enable the escape of the gas housed inside the sheath 52 that is needed for the inflation thereof ( Figure 6 ) .

Once inserted and inflated, the sheath 52 imbued with resin is made to harden through the curing (polymeri zation) of the resin with which it is imbued, until it forms the pipe 3 adhering to the pipe 50 to be repaired at the area 51 .

When the consolidation is finished, the hardened sheath 52 is cut at the ends 5 , or intermediate inspection wells that are not illustrated ( Figure 7 )

Both when laying a new duct 1 and when repairing the damaged duct 1 , the movement of the fluid generates an axial thrust on the pipe 3 that would tend to make it slip out of the connection elements 6 . In particular, the pressure acting on the components downstream or upstream of the pipe 3 with reference to the direction in which the fluid flows generates a similar axial thrust on the pipe 3 itsel f . This axial thrust is generated, by way of non-limiting example , at curved sections of the pipe 3 or when the interception elements arranged downstream of the pipe 3 itsel f are being closed .

This axial thrust is counteracted by the coupling between corrugations 15 and 16 , which ensure a stable and correct positioning of the pipe 3 in relation to the connection elements 6 .

At the same time , the pressure of the fluid generates a radial thrust on the corrugation 15 that keeps the corrugation 15 firmly in contact with the corrugation 16 , increasing the binding action exerted on the pipe by the coupling between the corrugations 15 , 16 .

The seals 7 ensure the fluid-tight connection between the pipe 3 and the pipes 3 adj acent to it of the duct 1 .

The seals 70 ensure the fluid-tight connection between the corrugations 15 , 16 .

From an examination of the duct 1 and the method according to this invention, the advantages that it enables are clear .

In particular, the coupling between the corrugations 15 , 16 generates an axial reaction thrust on the pipe 3 that counters the dynamic action exerted on the pipe 3 itsel f by the fluid that flows inside of the same pipe 3 .

This coupling also counteracts the same axial action that the pressure acting on the components downstream or upstream of the pipe 3, with reference to the direction in which the fluid flows, and rigidly connected to it, may generate on the pipe 3 itself.

It is, thus, possible to ensure the stable and precise positioning of the pipe 3 in relation to the connection elements 6.

Moreover, the binding action of the pipe 3 in relation to the connection elements 6 is increased by the pressure of the fluid flowing inside the pipe 3. This pressure, in fact, generates the radial thrust between the corrugations 15, 16 ensuring its stable contact radial to the axis A.

It is important to highlight how this binding action is obtained without the use of adhesives between the corrugations 15, 16, but simply thanks to the shape coupling between the corrugations 15, 16.

It is, also, important to highlight how the seal between the pipes 3 and the connection elements 6 is obtained thanks to the seals 7, i.e., thanks to the elements separate from the corrugations 15, 16.

Finally, it is clear that the duct 1 and the method described above may be altered, or variations may be produced thereof, without, as a result, departing from the scope of protection of this invention. In particular, the duct 1 may comprise , instead of one or both flanges 4 , corresponding interception elements , valves , or hydraulic j oints , provided with the surface 11 with the corrugation 15 . Each pipe 3 could, in addition, be produced in subparts assembled using electrowelding .

Each pipe 3 could, in addition, be formed from two hal f-bearings j oined using plates bolted together .

The flanged elements 4 could, in addition, be produced using mechanical processing, moulding, melting, sintering, electrowelding, or cold or hot plastic deformation .

The flanged elements 4 could, in addition, be welded to the connection elements 6 . The surfaces 13 of the flanged elements 4 could, in addition, comprise a corrugation 17 with basically the same shape as the corrugations 15 , 16 ( Figures 3 and from

5 to 11 ) .