WO2015082865A1

WO2015082865A1 - Flexible tubular pipe with resistant retaining layer

Info

Publication number: WO2015082865A1
Application number: PCT/FR2014/053210
Authority: WO
Inventors: Frédéric DEMANZE
Original assignee: Technip France
Priority date: 2013-12-06
Filing date: 2014-12-08
Publication date: 2015-06-11
Also published as: FR3014533A1; FR3014533B1; BR112016012387B1; DK179535B1; GB2535923A; GB2535923B; GB201609629D0; DK201670487A1

Abstract

The invention relates to a method for producing a flexible tubular pipe (10) and to a pipe thus obtained. Said method involves the following steps: a) a tubular structure is supplied; b) at least one plurality of armour wires is wound in a helix with a long pitch around said tubular structure in order to form at least one layer of tensile armour wires (22, 24); c) a retaining strip (30) is wound in a helix with a short pitch onto said at least one layer of tensile armour wires (24) in order to be able to form a retaining layer (32). Between step b) and step c), a continuous protective layer (28) is furthermore applied to said at least one layer of tensile armour wires (24) so as to insulate said retaining layer (32) and said at least one layer of tensile armour wires (24) from one another.

Description

Flexible tubular pipe with resistant holding layer

The present invention relates to a flexible tubular conduit for the transport of hydrocarbons and a method for producing such a conduit.

A field of application envisaged is in particular, but not exclusively, that of the transport of hydrocarbons or injection of water in a marine environment between a seabed and an overhanging surface.

The so-called "unbonded" flexible tubular pipes, described in API 17J, "Specification for Unbonded Flexible Pipe" and API RP 17B, "Recommended Practice for Flexible Pipe" published by "American Petroleum Institute", include several metal layers and superimposed plastics giving them their mechanical properties and sealing properties vis-à-vis the hydrocarbon they carry and the surrounding environment.

Also, they generally comprise, from the inside to the outside, a metal carcass made of a stapled spiral strip, a pressure sheath made of polymeric material, a helical winding with a short pitch of a wire forming an arch of pressure, at least one layer of tensile armor wound with a long pitch around said pressure vault, and an outer protective sheath.

When these pipes are intended to be installed in the deep sea, during their manufacture, is winded in a short pitch helix a holding strip on the sheet of outermost tensile armor wires. These holding or reinforcement strips, contain the armor son of the last sheet of armor son. Indeed, when the pipes are subjected to high hydrostatic pressures, and particularly in the deep sea, as the internal pressure of the pipe decreases too much, precisely below the hydrostatic pressure, they are subject to "the effect reverse background. The pipe then undergoes axial compression efforts tending to make it shorten. When this is added, in a dynamic and turbulent environment, lateral constraints on the pipe, the armor wires of the armor layer of tension then tend to flare up and come to disorganize the driving irreversibly locally. These armor threads then form locally structures called "cage bird".

The retaining band layer is thus intended to prevent this irreversible swelling of the tensile armor wires. However, at very great depths, the retaining strips are sandwiched between the outer protective sheath, on which the hydrostatic pressure is exerted, and the layers of tensile armor wires that can swell. They are then not only subject, at high surface pressures, but also to an acid environment due to gases such as CO ₂ and H ₂ S, and also at high temperatures. Under these conditions, the degradation of the holding layer is accelerated and, when in addition the flexible pipe is driven in motion, it is degraded by friction between the outer protective sheath and the tensile armor son.

Also, it has been imagined to coat the holding strip with a polymeric material and then come to apply it against the traction armor ply. The polymeric material is then secured to the holding strip and forms only one with it. Reference can be made to WO2008 / 135 663 which describes such a holding strip. However, the strip thus coated is not preserved from degradation under any operating condition.

Thus, a problem that arises and that aims to solve the present invention is to provide a method that allows better preservation of the holding band when the pipe is operated under severe conditions.

For this purpose, and according to a first object, the present invention provides a method for producing a flexible tubular pipe intended for the transport of hydrocarbons, said method being of the type comprising in the following order the following steps: tubular tubular structure having an outer surface and an inner surface defining a flow area; then, b) winding at a long pitch around said tubular structure at least a plurality of armor wires to form at least one ply of tensile armor wires bearing on said outer surface of said tubular structure; and, c) a holding strip is wound in a short pitch helix on said at least one ply of tensile armor wires so as to form a holding layer capable of radially holding said armor wires. Enter step b) and step c), there is further applied to said at least one layer of tensile armor wires, a continuous protective layer so as to isolate one from the other, said layer of maintaining and said at least one ply of tensile armor wires, and after step c), further applying a further protective layer to said holding layer.

Thus, a characteristic of the invention resides, firstly, in the implementation of a continuous protective layer wound around the at least one layer of tensile armor wires, preferably around the outermost layer. , and directly applied against it, so as to then be able to wind the retaining band applied on the protective layer, and secondly in the implementation of another continuous protective layer on said holding layer. In this way, the holding layer and the ply of tensile armor wires are isolated from one another, and thus the holding layer is preserved from the phenomena of friction and wear with the strands. armor of the tablecloth of tensile armor wires. In addition, the protective layer is a heat shield vis-à-vis the heat released by the hydrocarbon flowing inside the pipe and therefore, the holding band sees its temperature attenuated compared to a situation where the pipe does not have a continuous protective layer. In addition, it also constitutes a barrier layer vis-à-vis the acidic gas transported by the hydrocarbon, and therefore, it limits the risk of deterioration of the holding layer and minimizes the acid pH of the surrounding environment.

Also, the retaining layer is sandwiched coaxially between two layers of protection, one preserving it from the inside with respect to the armor wires of the tensile armor layer, high temperatures and acid gas, the other preserving it from the outside vis-à-vis the outer sealing sheath. In this way, the two protective layers preserve the holding layer vis-à-vis the relative movements of the traction armor ply and the outer sealing sheath, and thus wear phenomena.

The protective layer is integral and distinct from the holding layer, unlike the holding strips according to the prior art made in two parts prior to their application. So, the protective layer plays its role as a bulwark vis-à-vis the armor son of the traction armor ply.

Furthermore, according to a particularly advantageous embodiment of the invention, the at least one layer of tensile armor wires is wound in a short pitch, a strip of a polymeric material forming overlapping turns to apply said layer. continuous protection.

Thus, by means of an installation equipped with a ribbon, usually used for the production of flexible tubular conduits, a strip of the polymeric material is applied, taking care to overlap the turns so as to completely cover the defined surface. by the web of tensile armor wires. Thus, the continuous protective layer preserves the holding layer from contact with the web of tensile armor wires. It will be observed that the strip of the polymeric material is applied with a much lower voltage and in no way comparable to that of the tension printed on the holding strip. Also, all the qualities of the strip of the polymeric material intended to form the protective layer are retained, unlike the coating of the holding strips produced according to the prior art.

According to another embodiment of the invention, a sheath of a polymeric material is coaxially extruded on said at least one layer of tensile armor wires to apply said continuous protective layer. The securing of the protective layer is then maximal in all directions. In addition, the mandrel extrusion heads for forming sheaths are commonly used to produce the flexible tubular conduits. Preferably, the polymeric material is polyamide or else polypropylene.

Advantageously, a strip of a polymeric material is wrapped in a short pitch on said holding layer by forming overlapping turns to apply said other continuous protective layer. When the first protective layer between the holding layer and the traction armor layer is already made by means of a strip of a polymeric material, it is easier to provide for the application of a protective layer. second band on the holding layer with the same tape. However, in some applications, regardless of the embodiment of the first protective layer, a sheath of a polymeric material is advantageously coaxially extruded onto said retaining layer to apply said further continuous protective layer.

In addition, according to another particularly advantageous characteristic, an outer sealing sheath is formed around said holding layer. Thanks to this external sealing sheath, the armor is preserved vis-à-vis the water of the marine environment, which makes it possible to slow the process of corrosion.

According to another object, the present invention relates to a flexible tubular conduit for the transport of hydrocarbons, said flexible tubular conduit comprising: a tubular sealed structure having an outer surface and an inner surface defining a flow zone; at least one ply of tensile armor wires bearing on said outer surface of said tubular structure, said at least one ply of tensile armor wires being formed of the helical winding with a long pitch of at least one a plurality of armor wires around said tubular structure; and a retaining layer formed of the short pitch helical winding of a retaining band on said at least one ply of tensile armor wires, for radially holding said armor wires. In addition, the pipe comprises, on the one hand, a continuous protective layer situated between said holding strip and said at least one layer of tensile armor wires so as to isolate said holding strip from said at least one layer of traction armor wires and secondly, another protective layer continues on said holding layer.

Such protective layers provide all the advantages mentioned above. Preferably, according to an alternative embodiment, said continuous protective layer is formed, on said at least one layer of tensile armor wires, of overlapping turns of a strip of a polymeric material. According to another variant embodiment, said continuous protective layer is formed on said at least one layer of tensile armor wires by coaxial extrusion of a sheath of a polymeric material. In addition, said further continuous protective layer is preferably formed on said coaxial extrusion retaining layer of a sheath of a polymeric material.

Other features and advantages of the invention will become apparent on reading the following description of particular embodiments of the invention, given by way of indication but not limitation, with reference to the accompanying drawings in which:

- Figure 1 is a schematic perspective cutaway illustrating a flexible tubular pipe obtained according to the invention according to a first embodiment; and,

- Figure 2 is a schematic perspective cutaway illustrating a flexible tubular pipe obtained according to the invention according to a second embodiment.

The object of the invention, according to a first aspect, is a method of manufacturing a flexible tubular pipe intended for the transport of hydrocarbons in a marine environment. Reference will firstly be made to FIG. 1, which partially shows a flexible tubular conduit 10 broken away in order to describe the successive steps in the manufacture of the pipe. This figure illustrates the different superimposed layers which form the pipe and these are successively formed on each other, from the inside 12 of the pipe towards the outside 14. The interior 12 forms an internal flow space of the hydrocarbon.

According to the invention, a pressure sheath 16 made of a polymer material by hot extrusion and defining an internal surface 17 is provided first. The polymer material used is advantageously a semi-crystalline thermoplastic material. This pressure sheath 16 is tight and sufficiently thick to withstand the flow of a hot hydrocarbon.

Then, the pressure sheath 16 is covered with a pressure vault 18 made of a wire of substantially rectangular cross-section, wound in a short-pitch spiral, forming contiguous turns 20. The turns 20 are applied radially on the outer surface of the pressure sheath 16. The pressure vault 18 makes it possible to take up the external forces exerted radially by the hydrostatic pressure on the flexible tubular pipe in a marine environment and the radial internal forces exerted by the circulation of the hydrocarbon fluid within the internal flow space. In this way the pressure sheath 16 is preserved.

The pressure vault 18 defines an outer surface 21, which is then covered with two plies 22, 24 of a plurality of armor son wound with a long pitch and in two opposite directions from each other. The armor of these plies 22, 24 are said, traction armor, because they allow to resume the traction forces exerted on the pipe both during its installation on site, in operation. The outermost armor ply 24 defines a cylindrical bearing surface 25.

According to a first variant embodiment, a first strip 26 of a polymer material is wrapped in a short pitch around the sheet of outermost armor wires 24 in order to apply it against the cylindrical bearing surface 25. The polymer material implemented is preferably resistant to hydrolysis phenomena. It is chosen, for example, from the family of polyolefins, or polymers of vinylidene fluoride, or in the family of polyamides. The first strip 26 made in one of these materials is wound in a helix with short pitch by means of a tape, against the sheet of armor son 24 so as to overlap the edges of the turns. In this way, a first continuous protective layer 28 completely covering the cylindrical bearing surface defined by the ply of armor yarns 24 is obtained. The first strip 26 is applied in a relatively tense manner so as to form the first layer. protection 28 relatively secured. Its width is for example between 20 mm and 120 mm, for example 75 mm while its thickness is for example between 0.5 mm and 5 mm.

An alternative to this first embodiment comprises the simultaneous winding at short pitch of two first strips 26 by means of the ribbon so that the edges of the turns of each of them overlap.

The first protective layer 28 thus defines a continuous cylindrical outer surface on which is also wound in a pitched helix The retaining band 30 is wound with a high tension around the first protective layer 28, forming preferably adjoining turns so as to obtain a holding layer 32. It is for example made from aramid fibrous elements. Its width is for example between 20 mm and 60 mm and its thickness between 1 mm and 5 mm.

Then, a second strip 34, made of the same polymer material as the first strip 26, is wound in a short pitch on the holding layer 32 and according to the same method so as to obtain a second protective layer 36.

According to one variant, the second band 34 is made of a different polymer material from that used to make the first band 26. It is chosen according to the material of the first band 26 and the temperature generated by the hydrocarbon circulating in the first band. internal flow space.

Then, an outer sealing sheath 38 in a thermoplastic polymer material is extruded on the second protective layer 36 by means of an annular extrusion head. Thus, the retaining layer 32 is sandwiched between the outermost armor ply 24 and the outer sealing sheath 38, but is preserved on the inner side and the outer side respectively by the first protective layer. 28 and by the second layer protection 36. In this way, when the ply of armor son 24 tends to swell, under the double effect of the pressure differential between the outside and the inside of the pipe, and movements of the pipe, and that in contrast, the outer sealing sheath 38 is subjected to centripetal radial forces due to the hydrostatic pressure, the retaining strip 30 is preserved from abrasion and wear, due to relative movement of the ply of tensile armor wires and the external sealing sheath 38. These relative movements are locally reflected by the movements of the surface portions, following the tangent planes of these surface portions.

In addition, the first protective layer 28 constitutes a heat shield for the holding layer 32 with respect to the thermal energy released by the hydrocarbon circulating in the internal flow space, and which propagates radially through conduction in the thickness of the pipe. in addition, it also constitutes a barrier layer with respect to the acid gases transported by the hydrocarbon and therefore it limits the risks of deterioration of the holding layer and minimizes the pH of the acidic environment.

In this way, the aging of the holding layer 32 is slowed down, and thus the operating time of the pipe 10 is increased.

It will be observed that the implementation of the only first protective layer 28 already makes it possible to preserve the holding layer 32, both the abrasion of the sheet of armor wires 24 and the heat and acid gases. Also, it is envisaged to produce a flexible tubular conduit comprising the only first protective layer 28, when the operating conditions are substantially less severe.

In an alternative embodiment of the invention, it is preferred first of all to supply a metal carcass 8 made of an interlocked spiral strip onto which the pressure sheath 16 is then extruded.

Referring now to Figure 2, illustrating a flexible tubular conduit 10 'obtained according to the invention according to a second embodiment. The elements presenting here the same function will carry the same reference affected by a sign: "'".

The flexible tubular conduit 10 'has in the same way and in an identical arrangement, a pressure sheath 16', a pressure vault 18, and two plies 22 ', 24' of a plurality of armor wires each.

The outermost armor ply 24 'is then covered with a continuous protective layer 28' obtained by extrusion of a polymeric material. To do this, the tubular element constituted by the pressure sheath 16 ', the pressure vault 18' and the two armor plies 22 ', 24' is then driven through an annular extrusion head making it possible to form and applying the first continuous and cylindrical protective layer 28 ', precisely on the outermost ply of wires 24'. Such a protective layer 28 'is by construction, perfectly continuous and sealed along its current length. Also, it can provide additional protection to at least partially preserve the son of the armor plies 22 ', 24' vis-à-vis the water of the marine environment that could infiltrate from the outside. This protective layer 28 'also makes it possible to contain the gases of the hydrocarbon diffusing in the thickness of the pressure sheath 16'.

Advantageously, the polymer material chosen to produce the first protective layer 28 'is one of the materials with a high coefficient of thermal insulation. It is propylene, polyethylene, polyvinylidene fluorides, or polyamides and thermoplastic elastomers. In this way, the first protective layer 28 'is a heat shield vis-à-vis the heat provided by the hydrocarbon flowing inside the pipe 10' and more specifically, inside the pressure sheath 16 '.

A holding band 30 'is then wound, in the same way as for the previous variant, with a high tension around the first protective layer 28' forming turns, preferably contiguous, so as to obtain a layer maintaining 32 '. It can also be made based on fibrous aramid elements. Its width is for example between 20 mm and 60 mm and its thickness between 1 mm and 5 mm.

Then, the assembly is again brought through the annular extrusion head to apply, on the retaining layer 32 ', the second continuous protective layer 36' of polymeric material. The material used is for example identical to that used for the first protective layer 28 '. Preferably, the polymeric material is selected from chemically stable polymers, such as polypropylene, polyethylene, or thermoplastic elastomers. Also, the use of polyamides is also possible.

Finally, the outer sealing sheath 38 'is extruded coaxially on the second protective layer 36'.

According to these alternative embodiments, the risk of creep of the holding strips 30 'through the gaps of the traction armor plies 24' is very low. Also, the risk of contact of the retaining strips 30 'with the hydrocarbon gases are almost zero.

In addition, as in the previous embodiment, the holding layer 32 'is preserved on the inner side and the outer side respectively by the first protective layer 28' and the second protective layer 36 '. Therefore, when the sheet of armor son 24 'swells, under the double effect of the pressure differential and the movements of the pipe, and in contrast, the outer sealing sheath 38 is subjected to centripetal radial forces due to the hydrostatic pressure, the holding strip 30 'is preserved from abrasion and wear, due to the relative movement of the web of tensile armor wires and the outer sealing sheath 38 '.

Preferably, in an alternative embodiment of the invention, a metal casing 8 'is firstly provided made of an interlocked spiral strip on which the pressure sheath 16 is then extruded.

According to another object, the present invention also relates to a flexible tubular conduit, 10, 10 ', obtained in accordance with one or the other embodiments of the method described above.

Claims

1. Process for producing a flexible tubular pipe (10) intended for the transport of hydrocarbons, said method being of the type comprising, in the following order:

a) providing a sealed tubular structure having an outer surface (21) and an inner surface (17) defining a flow area;

b) at least a plurality of armor wires are wound in a long pitch helix around said tubular structure so as to form at least one ply of tensile armor wires (22, 24) resting on said outer surface (21); ) of said tubular structure;

c) a holding strip (30) is wound in a short pitch helix on said at least one layer of tensile armor wires (24) so as to form a holding layer (32) able to hold said wires radially. armor; characterized in that between said step b) and step c), a continuous protective layer (28) is applied to said at least one web of traction armor wires (24) so as to isolating one from the other, said holding layer (32) and said at least one ply of tensile armor wires (24), and that after step c), a further another continuous protective layer (36) on said holding layer (32).

2. Method according to claim 1, characterized in that is wound in a short pitch on said at least one ply of tensile armor son (24), a strip (26) of a polymeric material forming overlapping turns for applying said continuous protective layer (28).

3. Method according to claim 1, characterized in that coaxially extrudes a sheath of a polymeric material on said sheet of traction armor son to apply said continuous protective layer (28 ').

4. Method according to any one of claims 1 to 3, characterized in that a strip (34) of a polymeric material is wound in a short pitch on said holding layer (32) by forming overlapping turns to apply said further continuous protective layer (36).

5. Method according to any one of claims 1 to 3, characterized in that coaxially extrude a sheath of a material polymer on said holding layer (32) for applying said further continuous protective layer (36).

6. Method according to any one of claims 1 to 5, characterized in that forms an outer sealing sheath (38) around said holding layer (32).

Flexible tubular pipe (10) for the transport of hydrocarbons, said flexible tubular pipe comprising:

a sealed tubular structure having an outer surface (21) and an inner surface (17) defining a flow area;

at least one ply of tensile armor wires (22, 24) resting on said outer surface (21) of said tubular structure, said at least one ply of tensile armor wires (22, 24) being formed long pitch helical winding of at least a plurality of armor wires around said tubular structure;

a holding layer (32) formed of the short pitch helical winding of a holding band (30) on said at least one layer of traction armor wires (24), in order to be able to maintain said wires radially. armor;

characterized in that it further comprises, on the one hand, a continuous protective layer (28) located between said holding strip (32) and said at least one layer of traction armor wires (24) so as to isolating said retaining band (32) from said at least one ply of tensile armor wires (24), and secondly another continuous protective layer (36 ') on said retaining layer (32').

8. flexible tubular pipe according to claim 7, characterized in that said continuous protective layer (28) is formed on said web of tensile armor son (24), of overlapping turns of a strip (26) d a polymeric material.

9. Flexible tubular pipe according to claim 7, characterized in that said continuous protective layer (28 ') is formed on said web of tensile armor wires (24') by coaxial extrusion of a sheath. a polymeric material.

Flexible tubular pipe according to any one of claims 7 to 9, characterized in that said further continuous protective layer (36 ') is formed on said one holding layer (32') by coaxial extrusion of a sheath. a polymeric material.