EP1483068B1 - Method for making a plated steel armouring wire for a flexible tubular pipe transporting hydrocarbons, and armoured pipe - Google Patents

Abstract

A process for manufacturing plated-steel armor wires intended for reinforcement of flexible tubular pipes for transporting hydrocarbons, comprising a plating coating is intimately bonded, by high pressure, to a core made of hardenable steel with moderate mechanical properties, and then the plated wire obtained undergoes a rapid high-temperature hardening step followed by a tempering step.

Description

The present invention relates to a method of manufacturing plated steel armor wires for reinforcement of tubular pipes flexible for the transport of hydrocarbons, in particular non related ("unbonded flexible pipes"), according to the preamble of claim 1 as well as such a tubular pipe according to the the preamble of claim 10 (see, for example, JP-A-60 255 923). These behaviors are defined in the API 17J and 17B recommendations from the American Petroleum Institute and have metal layers and separate polymeric layers, that is to say, not linked together so as to allow a certain relative displacement between the layers.

• une gaine d'étanchéité interne, réalisée en matière plastique généralement polymère, résistant à l'action chimique du fluide à transporter ;
• éventuellement une voûte de pression résistant principalement à la pression développée par le fluide dans la gaine d'étanchéité et constituée par l'enroulement en hélice à pas court (c'est-à-dire avec un angle d'enroulement voisin de 90° par rapport à l'axe de la conduite) autour de la gaine interne, d'un ou plusieurs fils métalliques de forme agrafés (auto-agrafables ou non) ; les fils de forme ont une section en Z ou en T ou leurs dérivés (teta ou zeta), en U, ou en I ;
• au moins une nappe (et généralement au moins deux nappes croisées) de fils d'armure de traction enroulés à pas long ; l'angle d'armage mesuré sur l'axe longitudinal de la conduite est par exemple sensiblement égal à 55° ; et
• Eventuellement une gaine de protection et d'étanchéité externe en polymère.

More specifically, an unbonded pipe of the type referred to in the invention generally comprises, from the inside towards the outside:

• an internal sealing sheath, made of generally polymeric plastic material, resistant to the chemical action of the fluid to be transported;
• possibly a pressure vault mainly resistant to the pressure developed by the fluid in the sealing sheath and constituted by the short-pitch helical winding (that is to say with a winding angle close to 90 ° by relative to the axis of the pipe) around the inner sheath, one or more stitched metal wires (self-staple or not); the form wires have a Z or T section or their derivatives (teta or zeta), U, or I;
• at least one web (and generally at least two crossed webs) of tensile armor wires wound at a long pitch; the arming angle measured on the longitudinal axis of the pipe is for example substantially equal to 55 °; and
• Possibly a protective sheath and outer sealing polymer.

Such conduct may be smooth inside passage when the passage is directly formed by the sealing sheath (it is then called "smooth" boron ") or non-smooth passage (" rough bore ") when further inside the inner sealing sheath a carcass consisting of a staple-wrapped strap with a short pitch which serves to prevent crushing of the driving under external pressure. When using a carcass, it is possible for some applications to do without the pressure vault.

The pipe may optionally include in addition to these layers, other particular layers, a metal band (short-pitched) and forming part of the pressure vault, polymeric sheaths intermediaries, etc.

The exact constitution, number and arrangement of the various layers are carefully chosen according to the applications and conditions of use of the pipe, but we find in all conduct of the layers made by windings son of so-called strengthening or armor, steel.

For deep applications, which are the applications mainly referred to according to the invention, the driving generally comprises at the same time a carcass, a sealing sheath, a pressure vault, plies of tensile armor, and an outer sealing sheath.

For the purposes of the present invention, the armor threads considered are the armor threads pulling armor tablecloths crossed or possibly the form wires or the hoop wires of the pressure vault, which will be called pressure armor wires. By extension, we will hear also by wire of a form wire obtained according to the method of the invention and which would be intended to be used for the manufacture of a carcass.

When the pipes are intended for an acidic corrosive environment (in particular because of the H ₂ S contained in the effluents transported), often referred to in the oil jargon as a "sour" medium, special measures should be adopted to guarantee the Armor resistance (tensile and pressure) to corrosion. These measurements and the qualities of the appropriate steels are defined in the NACE (National Association of Corrosion Engineers) standard MR01-75 governing the resistance of steels and alloys to acid corrosion.

In most cases, steels with good H ₂ S corrosion resistance have relatively low mechanical properties (Rm <850 MPa). However, if we consider the conditions of use both corrosive and at great depth, it is advisable to preserve the mechanical qualities of the metal wires, in particular the armor wires, which will be subjected to both corrosion and stress. high traction encountered (for a "flowline" sea-bed transport pipe, these high tensile forces may not occur during the life of the pipe once laid, but at least at the time of laying the pipe) . If steel does not have very good mechanical properties, it is necessary to increase the thicknesses of steel used, which increases the weight of the pipes, the size of the winding and laying equipment and therefore the cost of returns from the pipes.

According to the document FR 2 775 050 which relates to an unbonded flexible pipe intended for static use in a corrosive environment, a corrosion-resistant steel H ₂ S is used, but with medium mechanical characteristics for the armor wires of the pressure vault. , and a steel with high mechanical characteristics but not resistant to acid corrosion for traction armor plies. This compromise seems acceptable if the H ₂ S corrosion can not reach the layers of tensile armor; for this purpose, an intermediate H ₂ S containment sheath separates the pressure vault that will be subjected to H ₂ S corrosion and the tensile armor plies, which will not in principle be subjected to this corrosion. However, safety is not guaranteed because of the risk of piercing the intermediate sheath. On the other hand, the poor mechanical characteristics of the steel used for the pressure vault lead to the obligation to oversize it.

In the field of linked pipes ("bonded pipes"), we know by document FR 2 569 461 a rubber hose intended for transport of corrosive effluents and incorporating reinforcements for this purpose consisting of layers of embedded wire ropes, the cables being made of steel wire coated with aluminum clad (that is to say in intimate with steel, obtained under high pressure of application, for example by co-extrusion). This pipe, manufactured using pipe technology related, is therefore of a constitution different from that of unrelated mainly envisaged according to the invention and which are subject to Tensile stresses unthinkable with this pipe technology linked. If one wants to retain the interesting idea of using armor plated in pipes of the type particularly considered in the present invention, it is necessary to consider plating wire with high mechanical properties (Rm greater than 1000 MPa and preferably at 1400 MPa) by a coating resistant to corrosion. However, the use of such high wire mechanical characteristics coated with anti-corrosion veneer gives not entirely satisfied, in particular because of a difficulty that the intimate bond of the coating with the steel is fragile and does not support the constraints related to the actual manufacture of pipes.

The object of the invention is to allow the reinforcement of the pipes flexible, including unbound pipes, by armor wires resistant to corrosion but also with good qualities to allow the use of the pipes at great depth. More specifically, the object of the invention is to find a method of Intimate coating or plating of the steel armor wires, compatible with the requirements of a use for a pipe of the aforementioned type used in acidic environment and in great depth.

The invention achieves its goal through a yarn manufacturing process plated steel armor for reinforcement of tubular conduits flexible, in particular unbound, for the transport of hydrocarbons, process of the type in which a veneer coating is intimately associated, by strong pressure, to a steel core, characterized in that the steel of the soul is chosen with medium mechanical characteristics and is what the coating is applied to the soul and intimately associated, then in that the plated wire obtained undergoes rapid quenching at high temperature followed by an income, so as to increase the mechanical characteristics plated wire.

The characteristics of steel and veneer coating, as well as the temperature and the time of quenching are selected in a related manner from to elevate the mechanical characteristics of the quenched wire without destroying the strength of the veneer bond. One of the key factors of the invention is the rapidity of the high temperature heat treatment which, in connection with the other parameters, makes it possible to minimize the constraints at the level of the between the steel and the coating, in particular by avoiding the migration of the carbon and iron steel in the bond and coating.

According to the invention, the core of the armor wire is medium resistance, that is to say whose resistance Rm is between 500 and 1000 MPa, advantageously between 800 and 900 MPa. It must be a "hardenable" steel (able to undergo tempering improving its mechanical characteristics, the quench consisting, as we know, of a curing by heat treatment: austenization + cooling) carbon, alloyed or weakly alloyed.

The anti-corrosive coating is for example made of titanium or alloys of titanium, stainless steel, nickel or nickel alloys.

The veneer is made mechanically cold after a preparation adequate (mechanical or chemical deoxidation of surfaces), according to a technique allowing an intimate connection by pressure (for example co-extrusion or colaminage).

As a result of this operation, an assembly is obtained characterized by a base connection / veneer still fragile and by characteristics mechanical degraded by plastic deformation (low elongation). Such a product, at this stage, would not be compatible with formatting for armoring a pipe of the type considered in the invention.

According to the invention, the steel thus coated is subjected to a treatment thermal device with a short temper at high temperature and an income in order to minimize the constraints on the connection between steel and coating.

The heat treatment according to the invention makes it possible to improve the characteristics of the bond, restore the characteristics of ductility plating and to obtain the high mechanical properties of the metal of basis for the applications envisaged for this type of product.

This heat treatment is characterized by a thermal cycle at high temperature (900 ° C to 1100 ° C) short (a few seconds to a few tens of seconds) followed by rapid cooling and treatment at a temperature of the order of 400 ° C to 700 ° C and which is adjusted in depending on the desired mechanical characteristics, the income being over a period of a few minutes, advantageously between 10 and 20 minutes.

This heat treatment has the following effects, depending on the components of the armor:

For plating, the treatment restores ductility without leading to precipitation prejudicial to the resistance to corrosion.

For the connection, it allows an improvement of the resistance by relaxation of rolling or extrusion and diffusion stresses metallic. The income also allows a complementary improvement of the ductility by the relaxation of the differential stresses related to quenching.

For the base metal, the heat treatment will make it possible to obtain a hardened tempered structure associating very high characteristics mechanical properties (Rm greater than 1000 MPa and preferably 1400 MPa less) and sufficient ductility for the intended applications (approximately 5% elongation).

The invention also relates to a flexible tubular conduit for the transporting hydrocarbons, incorporating at least some armor threads manufactured according to the aforementioned manufacturing process. More precisely, the invention relates to a flexible tubular pipe for transport hydrocarbons, of the type comprising polymeric layers and unbound metal layers, metal layers with wound armor, characterized in that at least some of the armor threads are tempered and returned and are manufactured according to the method of the preceding claims. The invention is intended in particular to conduct of the type comprising at least one carcass, an inner sheath, a pressure vault comprising armor wires of pressure, webs consisting of tensile armor wires and a sheath exterior, characterized in that at least some of the armor wires are manufactured according to the method of the invention.

La figure 1 est une vue en perspective d'une conduite de type "rough bore", à laquelle s'applique l'invention,

La figure 2 est une vue schématique illustrant le procédé de fabrication de l'armure plaquée conformément à l'invention.

La figure 3 illustre schématiquement diverses sections possibles d'armures plaquées.

Other advantages and characteristics will be highlighted on reading the description which follows, with reference to the attached schematic drawings in which:

FIG. 1 is a perspective view of a "rough bore" type pipe, to which the invention applies,

Figure 2 is a schematic view illustrating the method of manufacturing the plated armor according to the invention.

Figure 3 schematically illustrates various possible sections of plated armor.

Figure 1 shows a "rough bore" type pipe that includes from inside to outside: a metal carcass 1, usually made by a staple strap wound with a short pitch and intended for resistance crushing under external pressure; an internal sealing sheath polymeric 2, a metal pressure vault, constituted here so traditional winding with a short pitch helix (winding angle generally close to 90 ° to the axis of the pipe) of a wire stapled form metal 3 doubled by short pitch helical winding of a wire 4, an armor 5 resistant to axial traction in the direction longitudinal direction of the pipe and typically consists of a pair of cross plies of long armor pull wire 6,7 (typically less than 55 ° with respect to the axis of the pipe), and a outer polymer sheath 8. Other layers such as other armor 9 and an intermediate sheath 10 may be provided according to the type and destination of the pipe.

The invention relates to the plating of the traction armor wires 6,7 also although pressure armor wires 3, 4 (where applicable), according to a treatment that is illustrated in Figure 2.

The starting wire 20 consists of a base metal core 21 to average mechanical characteristics (for example Rm from 800 to 900 MPa) and a coating 22 of metal plating. The base metal can be, for example, a base steel type chrome silicon (55SiCr V) in the state globulized to allow plating. The plating metal can be for example a nickel base (NiCrMo series 6x according to AISI) or an alloy nickel (8x series). Starting wire 20 passes through a coextrusion die 23, from which it emerges having the coating 22 closely related to the soul. so plated wire goes into a post 24 heat treatment at high temperature, typically at least 800 ° C and preferably at 1100 ° C, by for example by heating the wire by induction. This treatment is fast (from a few seconds to a few minutes at the most). There occurs a austenitization of the base steel. This treatment is followed by rapid quenching in a quench station (for example by air, water or oil) which accompanied by a controlled martensitic transformation and thus allows obtaining high mechanical characteristics, with a Rm of the order 2000 MPa. But the speed of the treatment makes it impossible to leave to diffuse harmful elements (iron, carbon) in the link which would degrade the quality of it and degrade the resistance to corrosion of the veneer. Induction heating is advantageous not only for its speed but also because it makes it possible to overcome problems related to the possible reflection of the coating.

The yarn thus obtained then passes through a station 26 of thermal income, at a temperature of the order of 450 ° C for about fifteen minutes.

It is possible, after plating by co-rolling or coextrusion of the station 23 and before the heat treatment of station 24, to provide intermediate treatment of the income type for example to restore the ductility and the quality of the connection.

It is advantageous to ensure that the characteristics match of the core 21 and the sheath 22, which will be relatively relatives. Their constituent materials will preferably be chosen from way that the difference between their respective characteristics of mechanical resistance Rm is not greater than 200 MPa. For now relatively small this difference between the wire and the coating, it improves the regularity of the distribution of the thicknesses of the coating and also the quality of the bond obtained.

It is possible to provide several layers of veneer. The thickness plating is generally of the order of 200 μm to 500 μm; she must be thick enough to withstand mechanical aggression and corrosion. It represents in section less than about 10% of the section total of the wire.

Figure 3 illustrates, as examples, four types of sections possible for plated armor wires. The round shape 30 is the most simple, but one can also consider a rectangular shape 31 or a in "zeta" 32 or "teta" 33, these forms being in themselves conventional for constitute driving reinforcement son.

Claims (10)

1. A process for manufacturing plated-steel armor wires (20) intended for the reinforcement of flexible tubular pipes for transporting hydrocarbons, of the type in which a plating coating (22) is intimately bonded, by high pressure, to a steel core (21), characterized in that the steel of the core (21) is chosen with moderate mechanical properties and is hardenable, in that the coating (22) is applied to the core (21) and intimately bonded thereto and then in that in the plated wire obtained undergoes a rapid high-temperature hardening step, accompanied by a controlled martensitic transformation, followed by a tempering step.
2. The process as claimed in claim 1, characterized in that the properties of the steel and of the plating coating, and also the time and temperature of the hardening step are chosen so as to raise the mechanical properties of the hardened wire without destroying the strength of the plating bond.
3. The process as claimed in any one of claims 1 and 2, characterized in that the high-temperature hardening step is carried out at a temperature of around 800°C to 1100°C.
4. The process as claimed in any one of claims 1 to 3, characterized in that the high-temperature hardening step is carried out for a time of a few seconds to a few minutes, at the very most.
5. The process as claimed in any one of claims 1 to 4, characterized in that the high-temperature hardening step is carried out by induction.
6. The process as claimed in any one of claims 1 to 5, characterized in that the tempering is carried out for a time of between 10 min and 20 min.
7. The process as claimed in any one of claims 1 to 6, characterized in that an intermediate tempering step is introduced before the rapid hardening step.
8. The process as claimed in any one of claims 1 to 7, characterized in that the plating metal is chosen from titanium and its alloys, stainless steel, nickel or its alloys.
9. The process as claimed in any one of claims 1 to 8, characterized in that the constituent materials of the core (21) and of the coating (22) are chosen so that the difference between their respective mechanical strength R_m properties is not greater than 200 MPa.
10. A flexible tubular pipe for transporting hydrocarbons, of the type comprising polymeric layers (2, 8) and nonbonded metal layers (1, 3, 4, 6, 7), the metal layers comprising wound armor wires (3, 4, 6, 7), characterized in that at least certain of the armor wires (3, 4, 3, 7) are manufactured according to the process of the preceding claims.

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