OA18571A - A method of assembling a tubular junction sleeve and a pipe liner tube by laser welding. - Google Patents

Abstract

The present invention relates to a method and a device for assembling two tubes (1, 2) comprising a tubular junction sleeve and an internal pipe lining tube made of thermoplastic materials by laser welding of two contact surfaces of revolution (1- 1, 2-1) applied against each other at the ends (1a, 2a) of the tubular sleeve of said casing tube overlapping coaxially.

Description

METHOD OF ASSEMBLING A TUBULAR JUNCTION SLEEVE AND A LASER WELDING LINER TUBE

The present invention relates to a method of producing the assembly by laser welding of tubes made of thermoplastic materials. More particularly, the present invention applies to the assembly of at least two tubes arranged end to end or overlapping at least in part coaxially.

More particularly still, the present invention relates to an assembly of (a) a tubular junction sleeve inserted inside a pipe, in particular an underwater pipe, at the junction between two steel pipe elements. welded or intended to be metallically butt welded, and (b) an internal lining tube or “liner” applied as an internal coating of said pipe elements.

The present invention relates more particularly to a device useful in an assembly method according to the invention and to a method of fitting a tubular connecting sleeve made of plastic material for the assembly of a pipe from said unitary pipe elements. and carrying out laser welding, said sleeve being applied and secured to said sleeve by laser welding at the junction between the end-to-end ends of two unit pipe elements.

The present invention relates more particularly to the assembly of pipes conveying corrosive fluids, in particular underwater pipes conveying pressurized sea water intended to be injected into oil field wells, and more particularly pipes. link resting on the seabed or bottom / surface connection pipes.

The present invention relates more particularly still to the connection of two unitary pipe elements with internal lining, and more particularly still elements of 24 m or 48 m in length installed on oil fields in deep sea, by 2000 to 3000 m, or even more, from laying vessels fitted with J-laying towers.

In a known manner, the ends of said pipe elements are assembled end to end by welding and the internal lining inside said pipe elements stops at a significant distance, for example 100 to 300 mm from the end of said pipe elements. pipe, so that heating of the steel wall during the welding of their ends does not damage said lining. The problem which then arises is to ensure protection against corrosion of the unsheathed zone between the end of the liner of the pipe element N and the end of the liner of the following pipe element N + l.

The implementation of laser welding is known for welding two plastic components in the form of a film, plate or injected part, which is welded to one another. To weld two plastic components to one another by laser welding, it suffices for the first component through which the laser radiation passes to be transparent or translucent at the wavelength considered, and the second component to be absorbent. This guarantees a localized heat concentration at the point of incidence of the ray or laser beam on the absorbent part which by conduction is transmitted to the transparent part in contact at the joint plane between the two transparent and absorbent plastic components respectively. .

Methods of assembling parts by laser welding are suitable for assembling tubes by assembling their ends end to end. In JP 2011/240669, it is actually about welding two parts of a tank. Two of the ends of two plastic tubular parts arranged end to end at their end surfaces are laser welded. The pressure exerted on the contact surfaces to be welded is directed axially (and not radially) and emphasis is placed on the end-to-end mechanical clamping device comprising clamping elements 40 for holding in fixing one against the other of the two parts. tubulars to be butt welded, said clamping elements 40 being positioned on the outside at the periphery of the two tubular parts to be welded. Finally, axial translations of the mirror which reflects a laser beam emitted in the axial direction of the two tubular parts from the outside of the two tubular parts and / or a variation in inclination of said mirror with respect to the axial direction are not envisaged. .

Document FR 2 382 970 also describes an assembly of end-to-end tubular parts by laser welding of their end front surfaces at 90 ° relative to the axial direction. Here again, a complex mechanical clamping device comprising pistons 18 acting on wedges 26 must be implemented to operate the pressure required to maintain pressure against each other the two tubular parts to be welded. It follows from the arrangement of this mechanical system that the orientation of the laser beam is necessarily at 90 ° relative to the axial direction and does not allow the variation of inclination of the mirror 42 relative to the axial direction on the one hand. , and / or its translation in the axial direction to move the incident laser beam.

In EP 722 824, there is described an electro-fusion tubular junction sleeve equipped with heating coils, making it possible to weld said sleeve with the internal liner (called “liner”), present in a steel pipe element, said sleeve. tubular junction sleeve allowing the assembly of two pipe elements end to end ensuring the junction between the two liners of the two pipe elements on the one hand and, on the other hand, allowing the realization of the junction weld between the two driving elements.

In WO 2010/041016, a sleeve is described which makes it possible to carry out electrofusion welding with a heating wire by the Joule effect between two pipes equipped with plastic liners. In WO 2012/017171, the applicant has described a method of assembling two steel pipe elements coated with an internal liner (also called “liner”) using a tubular junction sleeve, improved in terms of sealing, in particular in the context of on-site assembly from a ship at sea, of reduced length pipe elements suitable for fitting from a ship at sea.

To do this, in WO 2012/017171, the tubular junction sleeve is interposed between 2 steel pipe elements with an internal thermoplastic material lining assembled end to end, the ends of the two pipe elements being welded together. other. Said tubular junction sleeve made of thermoplastic material, preferably identical to that of said sleeve, is inserted inside the pipe at the level of the end-to-end ends of the two pipe elements, so that the end parts at the ends of said sleeve are, in part at least, in sealed contact respectively with end portions at the ends of said internal linings of the two pipe elements. Said tubular junction sleeve has at each of said end parts of the sleeve at the level of said sealed contact zone with the end parts of said liners a heating wire by Joule effect, preferably arranged in a spiral, on the outer surface of each said end part at the ends of said sleeve. Said sealed contact zone is a zone of fusion welding together of the constituent materials of each said end part of the sleeve and respectively each said end part of said liner in contact with one another and traversed by said heating wire.

This sealing of the sleeve / jacket contact is important in order to avoid any contact between seawater and the area of the weld opposite said tubular sleeve. Such direct contact could indeed lead, in the event of water penetration between the sleeve and the pipe, when the pipe is a water injection pipe, to electro-chemical corrosion phenomena of the steel pipe and welding insofar as said mechanical connection between the sleeve and the liner is not necessarily tight.

Said melting zone is obtained by electrically supplying said heating wire by the Joule effect creating heating of said zone at the level of the interface of said contact surfaces of the end parts of the sleeve and of the liner. In said fusion weld zone (hereinafter abbreviated “fusion zone”), the fusion is therefore carried out in this case by the known process called “electro-fusion”, which makes it possible to produce a relatively large sealed contact zone. in the area traversed by the heating wire and around it.

The electro fusion welding method imposes a minimum thickness of 8 mm of the end parts of the sleeve and of the liners to be welded to allow the electrical wires to pass through and have good efficiency. In particular, the fact that the sleeve must be traversed by the heating wire to reach its outer surface, which heating wire would then cause the sleeve to melt over its entire thickness if the latter is not thick enough.

Functionally, in view of its anti-corrosion properties, an internal liner of 1 to 5 mm would be sufficient. However, in view of the stresses exerted on the internal lining tube during its installation, the thermoplastic lining tube being introduced by traction and necking into a die inside the steel pipe, for unit elements of pipes of About 50 m, we should preferably not go below 3 mm thick because then the plating on the steel pipe could be of poor quality. The ideal thickness is therefore a liner of 3 to 5 mm.

The aim of the present invention is to do away with electro-fusion welding coils which tend to create defects in the weld zone, which can potentially make it more fragile, and which involve relatively large fusion zones and therefore require relatively long cooling times.

In general, the aim of the present invention is to provide fusion welding of plastic materials at the level of the assembly of two end-to-end or overlapping thermoplastic tubular elements which is more precise, more reliable and faster to perform.

Another aim is to provide fusion welding of thermoplastic materials for the assembly of two tubular elements which eliminates the risk of leaks which may travel along the heating wire, resulting in a non-tight weld as discussed in WO 2012 / 017171.

Another aim is to provide welding of a junction sleeve and of an internal pipe lining which makes it possible to use an internal lining of small thickness, in particular less than 5 mm.

To do this, the present invention provides a method of producing the assembly of tubes of thermoplastic materials, in which at least two tubes are assembled, characterized in that said assembly is carried out by laser welding of two contact surfaces of revolution. applied one against the other of respectively two parts of two tubes, preferably end parts, comprising at least:

- an end part of a first tube, transparent to the laser wavelength, and

- an end part of the second tube, absorbent at the wavelength of the laser, and said welding being carried out using a laser beam which is displaced in rotation (R) at 360 ° with respect to the longitudinal axis XX 'common to the first and second tubes, a laser device or a head of the laser device emitting said laser beam being disposed inside one of said first and second tubes such that said laser beam passes through firstly said transparent end portion of the first tube to reach an area of said rotational contact surface of the absorbent end portion of the second tube and, preferably, pressure is applied to said contact surfaces against each other , to achieve a fusion weld zone between said contact surfaces of revolution of the transparent part of the first tube and of the absorbent end part of the second tube, characterized in that said first tube is a tubular junction sleeve made of thermoplastic material inserted inside a pipe comprising at least two steel pipe elements, the two pipe elements each comprising an internal lining tube of plastic material each constituting a said second tube, said tubular junction sleeve being inserted at the end-to-end assembly of the unsheathed ends of the two pipe elements which are metallically welded or intended to be metallically welded to each other, said end parts of the sleeve and the liner being in contact with one another with the other, at the level of external surfaces of revolution of said end portions of the sleeve in contact with internal surfaces of revolution of said liners, said surfaces of revolution of said end portions of the sleeve and of the liner having the same axis of revolution as said pipe and overlapping in the axial direction, and said welding is carried out, preferably by applying a said pressure s ur the inner surface of said sleeve in the radial direction at said surfaces of revolution in contact.

It will be understood that said weld zone is located at the level of the contact points between said contact surface of the transparent part of the first tube and the contact points of the laser beam on said rotational contact surface of the absorbent part of the second tube. More particularly, the width of the weld zone corresponds substantially to the width of the laser beam, which is generally approximately 1 to 5 mm and is concentrated on the interface of the two contact surfaces to be welded by virtue of the reflection of the ray on the absorbent part.

It is also understood that said weld zone extends over the entire periphery of said contact surfaces of revolution when the laser beam is moved in rotation (R) through 360 ° with respect to the common axis XX 'of the tubes.

Laser welding results from the fusion between them of the constituent materials of the two contact surfaces, said weld being located at the level of the zone of the contact points of the laser beam on the contact surfaces. Said weld zone forms a sealed contact zone between said contact surface of the transparent part of the first tube and said rotational contact surface of the absorbent part of the second tube.

The term “laser beam” is understood here to mean a unidirectional beam of laser radiation and by “transparent to laser radiation” that said material allows more than 20% light to pass, preferably more than 50%.

Laser welding according to the present invention is advantageous in that it makes it possible to obtain a cleaner and more precise weld zone, in particular better localized and especially without lips or weld bead requiring possible machining.

Thus, in the case of laser welding technology, it becomes easier to provide a tubular junction sleeve to be welded which is of any shape, in particular with a clean cut perpendicular to the axis of the liner to which it must be assembled. appropriate and / or for thin liners, in particular less than 5 mm, as will be explained below.

Laser welding according to the present invention therefore provides an increased weld quality without risk of leakage with a reduced risk of weld failure, and due to the very precise location of the weld zone, a cooling time also reduced compared to electro-fusion with a coil and heating wire, the heat at the melting point being localized to the size of the beam.

The embodiment with a laser welding zone is advantageous in that it makes it possible to ensure a more complete and more reliable sealing of the contact surface between said end parts of the sleeve and of the liner in order to avoid any risk of metal solder contact with the water of the pipes when said pipe conveys water and thus avoid any risk of invasion of the area between the external surface of the sleeve and the internal surface of said pipe elements, which would not fail to create a narrowing of the internal diameter of the sleeve, that is to say of the passage section of the fluid, and therefore disturbances in the flow of the fluid inside the sleeve, not to mention the risk of contact of said welding with water, when said pipe conveys water.

Finally, laser welding according to the present invention offers the possibility of welding inside a tube at great distances, in particular at more than 1000m, thanks to a relatively light umbilical, containing the supply pipes and bundles of optical fibers for the transmission of the laser beam.

Another advantage of the present invention over electro-fusion welding is to eliminate the constraint of implementing heating wires and positioning the electrical connectors of the heating wires at the level of one of the tubes, in particular a so-called tubular junction sleeve. .

Another advantage of the present invention is that the energy required for the laser is relatively lower, for example of the order of 50 to 100 W, the laser melting in practice can be carried out over 1 to 2 mm of thickness. both on the transparent part and the absorbent part. The weld is all the less deep on the side of the absorbent part as the latter is more absorbent and therefore more loaded with opacifying agent, in particular carbon black.

Another advantage of this method of assembly by laser welding is that it allows easy control of the quality of the welding by analysis of the absorption of the welded zone. For this, it suffices to send under the same conditions with the same device on said weld area a second control laser beam and analyze the power absorbed by analysis using photosensitive cells of the second return beam reflecting on the non-welded areas as explained below.

All these advantages of laser welding according to the present invention make it possible to ensure maximum reliability as well as optimized operating times during the production of the weld as well as during its use for the assembly of tubes according to the present invention.

Such an embodiment is also advantageous in that it makes it possible to use a thinner liner than by electro-fusion welding.

For laser welding, unlike electrofusion welding; the thinner the thickness, the more efficient the welding because the absorption is lower.

The required thickness of the internal lining is mainly a consequence of the length of the pipe in which it is applied by plastic stretching, taking into account the risk of tearing or irreversibly stretching it during its installation.

Preferably, said internal liner and said tubular junction sleeve have a thickness less than or equal to 5 mm, preferably 3 to 5 mm.

Such an embodiment with thin internal linings of less than 5 mm is possible for pipe lengths on single pipe elements or trainsets of less than 100 m, or even less than 50 m for thicknesses of up to 3 m. mm.

Such an embodiment is doubly advantageous:

a) First of all, in this embodiment, the installation of the lining tube is easier because:

- due to the thinness of the liner, the traction required on the liner tube for its stretching during its installation is reduced, and

- Due to the small thickness of the sleeve, said cylindrical contact surfaces of said internal lining and said overlapping weld-in sleeve can be superimposed without requiring machining of the internal lining, that is to say of constant thickness and therefore without forming a said contact surface of reduced thickness relative to the thickness of the running part of said liner, and

b) Secondly, in the event of superimposition of the end parts of the sleeve and of the liner, the pressure drops can be reduced due to the small thickness of the sleeve, the internal diameter differential between the internal surface of said liner and that of said sleeve being low enough to no longer disturb the flow of fluid in the pipe. Thus, the pressure drops are overall reduced despite the effect of increasing the pressure drops resulting from the reduction in the internal diameter of the pipe with thin internal liners.

Said weld and sealed contact zone extends over the entire periphery of the outer surfaces of revolution of said end parts of the sleeve and of said inner surfaces of revolution of said end parts of the liner in contact with one another, that is to say - say 360 ° around their axis of revolution XX '. On the other hand, said sealed contact zone may extend over just part of the lengths in the axial direction of said surfaces of revolution of the end portions of the sleeve and liner in contact with one another.

It is understood that said surfaces of revolution of said end portions of the sleeve and of the liner have the same axis of revolution as said pipe and that said sleeve in position inside said pipe.

In a known manner, each said pipe element comprises an internal liner of plastic material, preferably thermoplastic, terminating at a certain distance L from the end of said pipe element, preferably at least part of the outer surface of each part. terminal at the ends of the internal liner can be locked by gluing against the corresponding internal surface of the steel wall of the pipe, using an adhesive preferably of the epoxy or polyurethane type.

In a still known manner, the tubular junction sleeve extends in an axial longitudinal direction XX 'of the pipe over a length covering at least the pipe lengths not covered with said liners, that is to say at least twice. said distance L.

We understand that:

- the outer surface of the running part of the sleeve adjacent to said end sleeve part is located opposite the parts of the inner walls of the ends of said assembled pipe elements not covered with said liner, and

- The end parts at the ends of the sleeve have surfaces of identical or complementary shapes to the surfaces of the end parts at the ends of said linings with which they are in contact.

More particularly, said laser beam is perpendicular to said contact surfaces or inclined (ai), preferably within a range of 0 to 60 °, with respect to the perpendicular to said contact surfaces.

More particularly still, said laser beam is inclined relative to the perpendicular to the contact surfaces to be welded at an angle of 30 to 60 °, in particular 45 °.

More particularly, said contact surfaces of revolution of said first and second overlapping tubes to be welded are of cylindrical or frustoconical shape with the same axis as the longitudinal axis XX 'of said tubes.

In an alternative embodiment, preferably for sleeves and lining with a thickness greater than 5 mm, in particular from 5 to 10 mm, said sleeve and lining are characterized in that:

- Said internal liner has at least one end an end portion of reduced thickness compared to the thickness of the main part of said liner, defining a concave shape with an internal surface forming a said contact surface of revolution, preferably frustoconical or cylindrical, with an internal diameter greater than that of the internal surface of the running part of said liner, and

- Said sleeve has at least one end an end portion of reduced thickness compared to the thickness of the adjacent running portion of said sleeve, said end portion of the sleeve defining a convex shape capable of overlapping and abutting against the concave end portion of 'reduced thickness of said liner with which it is in contact, said end part of the sleeve defining an outer surface corresponding to a said contact surface of revolution, preferably frustoconical or cylindrical, of outer diameter smaller than that of the adjacent running part of the sleeve and a cylindrical internal surface of substantially the same internal diameter as that of the running part of the liner and the running part of the sleeve, and laser welding of said inner surface of revolution constituting a said contact surface of said liner and of said outer surface of revolution constituting a said contact surface of said sleeve.

It is understood that, by virtue of their complementary shapes, said end part of the sleeve and end part of reduced thickness of the liner allow the sleeve to be inserted against the internal surface of the end part of reduced thickness of the liner by simple force-fitting of said sleeve in the axial longitudinal direction XX 'inside said duct member and the outer surface of said reduced sleeve end portion in contact with the inner surface of reduced liner thickness end portion have an identical shape and are arranged relative to each other to match their identical contour.

Preferably, said internal surface of the terminal portion of reduced thickness of the liner and external surface of the terminal portion of reduced thickness of the sleeve, in contact with one another, are of the same frustoconical shape with the same axis XX 'as said sleeve and said pipe.

It will be understood that, by virtue of their complementary concave and respectively convex shapes, said internal surface and frustoconical external surface have an apex angle of substantially the same value. In this embodiment with a frustoconical contact surface, said terminal portions of reduced thickness of the sleeve and of the sleeve in contact have a thickness increasing from the ends of the sleeve and respectively of the sleeve, towards the adjacent running part of the sleeve and respectively of the sleeve. , and the spiral of said weld zone (described below) progresses with turns increasing in diameter from its said first end located on the side of the terminal part of the sleeve of smaller thickness towards its said second end located on the side of the sleeve. end part of the sleeve of greater thickness.

In a variant, said internal surface of the terminal portion of reduced thickness of the liner and external surface of the terminal portion of reduced thickness of the sleeve, in contact with one another, are of the same cylindrical shape with the same axis XX '. that said sleeve and said conduit, preferably the end of the terminal portion of reduced thickness of the sleeve abutting against a shoulder delimiting the internal surfaces of said running portion and end portion of reduced thickness of the liner.

In this embodiment with a cylindrical contact surface, said terminal portions of reduced thickness of the sleeve and of the liner in contact have a preferably substantially constant identical thickness, and where appropriate the spiral of said weld zone progresses with turns of constant diameter from its said first end located on the side of the terminal portion of the sleeve of smaller thickness to its said second end located on the side of the terminal portion of the sleeve of greater thickness.

When the internal surface of the terminal portion of reduced thickness of the sleeve is conical or cylindrical, the spiral formed by said weld zone is three-dimensional, that is to say of spiral or helical shape because its turns are spaced apart in the direction lengthwise of the sleeve.

In the various embodiments referred to above with a contact surface of the end parts of the sleeve and conical or cylindrical sleeve, the contact surface has a cone-type topology, the half angle of which at the apex a 'is between 0 and 90 °. for conical surfaces, and of fictitious cone type with a half angle at the apex a = 0 ° for cylindrical surfaces, so that in all cases said first end of the spiral is located on the side of the tip of the cone or of the fictitious cone .

In another embodiment, especially in the case of internal lining and said sleeve are thinner, in particular less than 5 mm, the following are used:

a said internal lining having at least one end an end part of the same thickness as the thickness of the running part of said lining, defining a cylindrical internal surface corresponding to a said contact surface, of the same internal diameter as that of the surface internal part of the running part of said lining, and

- Said sleeve has at least one end an end portion of the same thickness as the thickness of the adjacent running portion of said sleeve, said end portion of the sleeve defining:

- a cylindrical outer surface corresponding to a said contact surface of revolution, of external diameter substantially identical to that of the internal surface of said liner and

- a cylindrical internal surface of internal diameter smaller than that of the internal surface of said lining,

- said end part of the sleeve thus being able to overlap in a superimposed manner the end part of said sleeve with which it is in contact, and

- Laser welding of said internal cylindrical surface constituting a said contact surface of said liner and of said cylindrical external surface constituting a said contact surface of said sleeve.

More particularly, a continuous weld zone of spiral or helical shape or a plurality of circular weld zones concentric or arranged side by side parallel along the axial direction of said contact surfaces is produced.

The width of a weld zone thus produced by laser welding corresponds to the width of the laser beam, ie in practice from 1 to 5 mm, preferably from 2 to 4 mm.

In one embodiment, the circles are space with a translation pitch of 1 to 10 mm, preferably 3 to 5 mm, or a helical or spiral-shaped weld area is formed, the pitch of the helix of which is is of the same value from 1 to 10 mm, preferably from 3 to 5 mm. A weld zone is thus obtained which does not cover the entire surface of said contact surfaces traversed in the direction of translation.

In another embodiment, a plurality of circular or helical or spiral zones is produced, the circles or helices or spirals of which of the weld zone are juxtaposed in a contiguous manner, by moving the laser head in translation by an identical value. to the width of the circular or helical or spiral zone, to obtain a weld zone with a surface of revolution, in particular frustoconical or cylindrical, continuously covering the entire cylindrical or frustoconical surface of said contact surfaces along the direction of translation and over any its periphery.

Also in practice, the helical or spiral weld area or the plurality of said circular weld areas extend for a length in the axial longitudinal direction of the contact surfaces from 30 to 100 mm.

More particularly still, the laser head is arranged so as to emit a said laser beam in a longitudinal direction of said tubes facing a mirror, preferably the axial direction XX ', so that said emitted laser beam by the laser head is reflected on the mirror surface, the mirror surface being inclined at an angle β with respect to the longitudinal axis XX 'of said tubes, preferably by an angle β of 30 to 60 °, by preferably 45 °, and said inclined mirror is mounted capable of pivoting (R) through 360 ° as well as said laser beam reflected by the rotating mirror (R) relative to the longitudinal axis XX ′ of said tubes.

More particularly, said laser head is disposed at the end of optical fiber (s) in an umbilical disposed in the longitudinal direction XX 'of the tubes providing the connection between the laser head and a laser device, the laser device being preferably disposed outside said tubes and said umbilical extending through said tubes.

It will be understood that said inclination of the mirror with respect to the longitudinal axis corresponds to a rotation of the mirror with respect to an axis perpendicular to the longitudinal direction XX 'of said tubes.

More particularly, in a first embodiment, said mirror is mounted capable of being further displaced in axial longitudinal translation (T) XX 'and a said translational displacement of said mirror is carried out in combination with a said rotation (R) of said mirror over 360 ° relative to said longitudinal axis XX 'of said tubes.

More particularly, said mirror is moved in translation continuously concomitantly with a said rotation (R) of the mirror over 360 ° relative to said longitudinal axis XX 'and in particular a helical or spiral-shaped continuous weld zone is obtained. longitudinal axis XX 'than said cylindrical or respectively frustoconical contact surfaces of said tubes overlapping.

More particularly still, said mirror is moved in step by step translation, said translation and a said rotation (R) of the mirror over 360 ° with respect to its longitudinal axis XX 'being carried out successively, said laser welding being carried out only during a said rotation (R) of the mirror. It is thus possible in particular to obtain a plurality of circular weld zones forming parallel coaxial circles along the same longitudinal axis XX 'as said contact surfaces of revolution of said overlapping tubes, said circular weld zones being spaced step by step or juxtaposed continuously. .

In practice, by way of illustration, said mirror is moved in continuous translation at a speed of 1 to 5 mm / turn, preferably 3 mm / turn, or in translation step by step at a rate of 1 to 5 mm / step, preferably 3 mm / step. The speed of rotation and the translation can be decoupled in order to control the deposition of energy in one go or by layers deposited successively in close time, preferably before cooling.

More particularly, in a second embodiment, the surface of said mirror is mounted capable of being inclined by an inclination B varying with respect to the longitudinal direction XX 'of said tubes and the angle B of said inclination of the surface is varied. of the mirror with respect to said longitudinal direction XX 'in combination with a said rotation (R) of said mirror with respect to said longitudinal axis XX'.

This embodiment makes it possible to vary the angle of the laser beam reflected by the mirror and forming the incident laser beam arriving on the surface of said absorbing part receiving said laser beam. And, the tilting displacement of the mirror surface and the resulting variation in the angle of the laser beam causes the same effect as the translational displacement of the mirror. This inclination can also be carried out step by step, that is to say discontinuously, or continuously.

In a first variant, a variation of said inclination of the mirror is carried out continuously and concomitantly with a said rotation (R) of the mirror over 360 ° relative to the longitudinal axis XX 'of said tubes. Thus, a so-called spiral-shaped weld zone is obtained in particular on said frustoconical or helical contact surfaces with the same longitudinal axis XX 'as said cylindrical contact surfaces of two overlapping tubes.

In another variant, a variation of said inclination of the mirror is carried out by step-by-step angular displacement, said inclination of the mirror and said rotation (R) of the mirror over 360 ° with respect to its longitudinal axis XX 'being carried out successively, and said laser welding being carried out only during one said rotation (R) of the mirror with respect to its longitudinal axis XX '. It is thus possible in particular to obtain a plurality of parallel side-by-side circular weld zones, along the same longitudinal axis XX 'as said contact surfaces of revolution of said overlapping tubes, said circular weld zones being spaced step by step or juxtaposed continuously. .

In practice, by way of illustration, said tilting mirror is moved continuously at an angular displacement speed of 0.1 to 5 ° per revolution, preferably 0.5 ° per revolution, or by angular displacement step by step at 0.1 to 5 ° / step, preferably 0.5 ° / step.

In an alternative embodiment, preferably for liner thicknesses of at least 10 mm, said internal liner tube is obtained by assembly by laser butt welding, alternately, of small lengths of first transparent liner tubes and long lengths of second absorbent liner tubes, by sending against the end end face annular surfaces of said first and second liner tubes in end-to-end contact, from a laser head within at least one of said tubes, a laser beam inclined relative to the coaxial longitudinal axis (XX ') of said tubes, said end frontal annular planar surfaces being perpendicular to the axis (XX') of the two first and second liner tubes, and preferably covers the short lengths of first transparent liner tubes with a coating the color of said second absorbent liner tubes.

It is understood that said straight front ends form annular flat surfaces extending in a direction perpendicular to the longitudinal direction XX 'of the tubes and are constituted by the section in right cross section of said ends.

More particularly, said laser beam is inclined relative to the perpendicular to the front contact surfaces to be welded together, at an angle of 30 to 60 °, in particular 45 °.

More particularly still, to assemble this lining tube by laser welding, a variation of said inclination is carried out by angular displacement step by step of said mirror successively at a said rotation (R) of said mirror over 360 ° relative to the longitudinal axis XX ', said laser welding being carried out during a said rotation (R) of the mirror through 360 ° relative to the longitudinal axis XX' of said tubes to produce a plurality of circular welding zones in the form of concentric circles.

In another embodiment, in order to assemble this lining tube, a said inclination is produced by continuous angular displacement of the mirror concomitantly with a said rotation (R) of said mirror over 360 ° relative to the longitudinal axis XX 'of said mirror for achieve a continuous weld area in the form of a plane spiral.

More particularly, in a variant, a said continuous translation is carried out concomitantly with a said rotation (R) of the mirror over 360 ° relative to the longitudinal axis XX 'of said tubes, and a said helical weld zone is obtained on said surfaces of cylindrical contact with turns of increasing diameters on said frustoconical contact surfaces.

More particularly still, in another variant embodiment, that a said step-by-step translation or a said inclination is carried out by step-by-step angular displacement of said mirror with respect to the longitudinal axis XX 'of said tubes, said inclination being carried out successively to a said rotation (R) of said mirror through 360 ° with respect to the longitudinal axis XX 'of said tubes by performing said laser welding during said rotation to produce a plurality of circular areas side by side, of the same diameter on said surfaces of cylindrical contact or of increasing diameters on said frustoconical contact surfaces.

More particularly, the transparent and absorbent thermoplastic materials of said tubes to be assembled by laser welding are, for example, PE, PP or PVDF and PEEK.

These materials are obtained translucent or made translucent with clarifying agents or nucleating agents or can be made opaque and absorbent to visible laser rays with opacifying agents, preferably mineral fillers, in particular carbon black. It is possible, if necessary, to adapt the filler rate, in particular of carbon black, as a function of the geometry of said parts to be welded, in particular of the thickness of said parts to be welded.

More particularly, said emitted laser beam is a laser beam whose color is in the visible spectrum, preferably green or red.

More particularly still, said laser welding is carried out by sending an energy beam of 1 to 5 W / mm ² , preferably 2 to 3 W / mm ² .

More particularly still, said rotations (R) of the mirror are carried out over 360 ° with respect to the longitudinal axis XX 'of said tubes at a speed between 0 and 100 Hz, preferably from 0.1 to 10 Hz, ie from 10 revolutions / seconds per revolution. / 10 seconds.

The quality of the weld will essentially depend on the energy deposited per unit area. Thus we can go 10 times to 0.2 W / mm ² or once to 2 W / mm ² for example. In practice, a good weld is achieved when a value of 1 to 3 W / mm ² has been deposited depending on the density of the plastic material considered.

Applying pressure during welding is an option depending on the quality and manufacturing tolerance of the liner and sleeve.

When the diameter of the sleeve is well calibrated in relation to the internal diameter of the liner with a difference of less than 0.25 mm, then without pressure, the welding is done perfectly without pressure. Indeed the transparent part of the sleeve which is partially absorbent stores heat from the laser and in fact, the sleeve by expansion is pressed against the opaque liner which could not expand due to the steel pipe which serves as its vaulted.

On the other hand, if the diameter differential between the external diameter of the sleeve vis-à-vis the internal diameter of the liner is more than 1 mm apart between the tubes, the application of pressure is required for the welding to take place. on parts in contact.

In a preferred embodiment, a control of the quality of the laser weld is carried out by sending on said weld zone a control laser beam, preferably emitted with the same device and under the same conditions of rotation, translation or inclination as the welding beam, and by analyzing using a sensor, preferably by absorption measurement, a control laser beam reflected on the weld zone, said control laser beam having a lower energy than said laser beam of welding, preferably an energy of 0.01 to 0.05 W / mm ² , and preferably said control laser beam being of identical frequency to that of the welding laser beam, more preferably a wavelength greater than 950 nm (at -beyond the visible).

The welding control laser beam follows the same path as the welding laser beam, emitted by the same laser fiber and same laser head and same mirror. A receiver comprising photosensitive cells and absorption measuring sensor capable of analyzing the reflected ray and determining the absorption rate makes it possible to visualize the variations in absorption without waiting for the sleeve to cool.

By analyzing the reflected laser light by imaging we can see the non-welded areas appear because the areas welded to the opaque liner absorb all the energy sent and therefore remain black while the non-welded areas appear white because there is reflection on the non-welded side of the sleeve.

It is advantageous to use the same wavelengths to perform the weld to control the weld in order to obtain equivalent results in terms of penetration into the transparent tube (equivalent absorption).

The present invention also provides a device useful for the implementation of a method according to the invention, characterized in that it comprises a mechanical system supporting a mirror and a said laser head connected to an umbilical, capable of s' fit and be moved inside said first and second tubes to be assembled and comprising:

- means of forced radial extension capable of resting against the internal surface of one of said first and second tubes to be assembled and creating a contact pressure at the level of the zone of said contact surfaces to be welded, and

- Means capable of moving said mirror in rotation (R) around the axial longitudinal axis XX 'of said first and second tubes to be welded, and

- means for moving in relative translation (T) said mirror with respect to said mechanical system, and / or

- Means for tilting (B) the surface of said mirror with respect to the axis XX 'of said first and second coaxial tubes to be assembled in which said mechanical system is inserted.

Said mechanical system supporting said mirror and said radial extension means, means of rotation and / or tilting means of the mirror, may be a motorized carriage or able to be moved in said pipe or a mandrel able to be moved in said pipe .

More particularly, the device comprises a mandrel supporting a laser head or a laser device and an inclined mirror β, said mandrel being able to be placed inside one of said tubes with the same longitudinal axis XX 'as said first and second tubes, said laser head and said inclined mirror being disposed axially inside said first and second tubes, and said mandrel supporting at least one transparent peripheral wall expandable radially by inflation, thus forming a first inflatable chamber capable of applying a pressure, preferably a pressure of 2 to 3 bars, against said contact surfaces of the two first and second tubes to be welded, said mirror being placed inside said inflatable chamber, said mandrel also supporting an umbilical, comprising at least one compressed air supply duct for inflating said first inflatable chamber and an electrical supply duct of a suitable motor in moving said mirror in rotation R as well as in said relative translation T or in said inclination β.

It will be understood that the device is thus able to carry out said laser welding by positioning said inflatable chamber facing said contact surfaces of the two tubes to be welded and by inflating said inflatable chamber so that said contact surfaces at weld can be pressurized against each other and by rotating (R) said mirror around the longitudinal axis XX 'of said tubes and said mandrel through 360 °, and moving the point of incidence of the laser beam on the contact surfaces to be welded in the longitudinal direction XX 'by relative translation (T) of said mirror with respect to said mandrel or by variable inclination (6) of said mirror with respect to said longitudinal axis XX', said translation or said inclination being able to be combined with said rotation (R) relative to the axis XX 'in particular to produce at least one circular weld zone or a helical or spiral-shaped weld zone.

More particularly still, said mandrel supports a motor capable of driving the rotation (R) of said mirror over 360 ° around the longitudinal axis XX 'of the mandrel, using a ball bearing and gear system.

More particularly, said mirror is able to be moved in translation or relative inclination with respect to the longitudinal axis of said mandrel by a worm mechanism slaved to said rotation (R) of said mirror around the longitudinal axis XX 'of said mandrel , or by a triggering lug of said translation or angular displacement step by step.

More particularly still, in a first embodiment, said mirror is capable of being moved in relative translation with respect to the longitudinal axis of said mandrel by a worm mechanism slaved to said rotation (R) of said mirror around the longitudinal axis XX 'of said mandrel in particular to produce a weld zone in the form of a spiral or helical, or by a step-by-step translation triggering lug, in particular to produce a plurality of side-by-side circular welds parallel respectively at each step.

More particularly still, in a second embodiment, said mirror is able to be moved in inclination (6) relative to the longitudinal axis XX 'of said mandrel by a worm mechanism slaved to said rotation (R) of said mirror around the longitudinal axis XX 'of said mandrel in particular to produce a weld zone in the form of a spiral or helical, or by a step-by-step angular displacement triggering lug in particular to produce a plurality of side-by-side circular welds parallel respectively to each step.

More particularly still, said mandrel also supports a weld control device comprising a sensor capable of analyzing, preferably by absorption measurement, a control laser beam reflected on the weld zone, said mandrel being connected to an umbilical comprising fiber optics and power lines.

More particularly still, said mandrel further supports a second inflatable chamber comprising a peripheral wall expandable radially by inflation, spaced from said first inflatable chamber in the longitudinal direction XX 'of said mandrel.

The method of positioning and the method of implementing the sleeve with the device according to the present invention are facilitated by the fact that said second chamber makes it possible to:

- facilitate guiding and allow easier longitudinal displacement of the device according to the invention inside a pipe and / or a sleeve, because the two said first and second chambers are partially inflated to a diameter slightly smaller than that of the pipe or respectively of the sleeve, the two chambers being spaced apart in the longitudinal direction so as to abut the wall of the pipe and of the sleeve and thus maintain the mandrel in the axial direction of the pipe or of the sleeve despite the counterweight represented by said weld control device, and

- Fixing the device according to the invention inside said sleeve, and thus stabilize the mandrel relative to said sleeve to adjust its position before carrying out said laser welding, by maximum inflation of said second inflatable chamber, the latter thus being pressed and secured to the internal wall of the sleeve, the position adjustment consisting in pre-positioning said first chamber facing said end portion of the sleeve to be welded after inflation of the first chamber, and

- Stabilize the device according to the invention with respect to said sleeve by maximum inflation of the two said first and second chambers thus pressed and secured to the internal wall of the sleeve, during the production of said laser welding and then during the mobile implementation of said means welding control.

Preferably, the two said first and second inflatable chambers extend over a length L1 and respectively L2 and are spaced by a distance d in the longitudinal direction of the mandrel such that when a said first inflatable chamber is in radial expansion plating against the end part of the sleeve, in particular when the latter is placed against the end part of the internal lining of the pipe to carry out the laser welding, the second inflatable chamber is located opposite and can come to rest against a part of the tubular internal wall of said sleeve.

The present invention also provides a method of placing a tubular junction sleeve at one end of a unitary pipe element with an internally lined thermoplastic material in order to secure a said sleeve at the end part of a said sleeve. , said sleeve having at each end an end portion of a tubular wall, preferably of reduced thickness compared to the thickness of the adjacent running portion of the tubular wall of said sleeve, and a weld zone is created by heating by laser beam and sealed contact by fusion with each other of the constituent materials of said end part of the sleeve and respectively of the end part of said liner in contact with one another, and traversed by said laser beam, using a device for fitting the sleeve according to the invention.

More particularly, the following steps are carried out, preferably on the deck of a laying vessel or on land:

1.1) said sleeve placement device is positioned inside said sleeve so that at least one said first inflatable chamber is in position vis-à-vis a first end part of the sleeve, the other said first and second inflatable chambers being opposite the internal wall of the running part of the sleeve and at least said second inflatable chamber is inflated so as to secure the sleeve placing device with said sleeve by pressing against the expandable wall of said second chamber against the inner wall of said tubular sleeve, and

1.2) the assembly thus formed of the sleeve and of said sleeve positioning device is moved in the longitudinal direction XX 'axially which is inserted inside an open end without a sleeve of a pipe element , until said first end portion of the sleeve is in contact with said end portion of the liner of said female end of said conduit member, and

1.3) said first inflatable chamber is inflated in order to press it against the internal wall of said first end sleeve portion, and

1.4) said welding laser beam is sent which is displaced in rotation and translation or inclination, preferably by simultaneously exerting a pressure of said end sleeve portion against said end sleeve portion in contact with one another by inflation of said first inflatable chamber to produce a said laser welding zone of the constituent materials of a part of said end part of the sleeve and respectively an end part of said liner in contact with one another, and traversed by said laser beam, and

1.5) the quality of the weld is controlled by sending a control laser beam which is moved in rotation and translation or inclination, said control laser beam being of lower energy than the welding beam and the ray reflected on the weld area, and

1.6) said first and second chambers are deflated and said sleeve positioning device is moved in translation in order to evacuate it.

It is understood that said pipe element obtained is found with a sleeve part on the side of the second free end part outside the pipe element corresponding to said male end of step a) of the pipe production process. hereafter.

The present invention also provides a method for producing a pipe using a sleeve fitting device according to the invention, in which the assembly of unit pipe elements comprising a said lining is carried out, and a said tubular junction sleeve inserted and fixed at only one end of each said pipe member and protruding therefrom, the protrusion of said sleeve defining a male end of each said pipe member adapted to be assembled with an end devoid of the pipe. said sleeve defining a female end of another said pipe element. By laser heating a weld zone and sealed contact is created by melting together the constituent materials of a said end part of the sleeve and respectively end part of said liner in contact with one another, and traversed by said ray laser, carrying out the following steps in which:

a) a sleeve positioning device is introduced inside said unitary pipe element so that said first inflatable chamber is disposed at an end portion of said sleeve, and said positioning device is fixed in place of a sleeve inside said sleeve by inflating a said second inflatable chamber against the internal wall of said sleeve, and

b) before or after step a), the sleeve part forming said male end of a pipe element is introduced and forcibly inserted into the female end of the other pipe element, in the longitudinal direction XX ' axially, until said end portion of the sleeve of said male end of said terminal pipe member contacts said terminal portion of the liner of said female end of said pipe member to be assembled, and

c) the outer peripheral welding of the ends of the two pipe elements is carried out end to end by metal welding, and

d) inflating a said first inflatable chamber at the level of said end part of the sleeve which is opposite it, and sending a said laser beam, preferably by simultaneously exerting pressure on said end part of the sleeve against said liner end portion in contact with one another to produce a said fusion weld zone at a portion of the contact surfaces of each said end portion of the sleeve and each said end portion of the sleeve in contact one with the other and traversed by the laser beam, to produce a so-called weld zone and sealed contact by fusion, and

e) the quality of the weld is controlled by analysis, preferably by absorption measurement, of a control laser beam reflected on the weld zone, and

f) said first and second inflatable chambers are deflated and said sleeve placement device is moved in translation.

More particularly, the following steps are carried out in which:

al) a first pipe element equipped with a said sleeve at one of its ends is lowered into a pipe laying tower of a pipe laying vessel, up to near the end of the upper terminal pipe element the pipe under assembly partially submerged at the bottom of the tower, and

a.2) a said sleeve placement device is lowered with said first and second chambers at least partially deflated, which is secured to a said sleeve fixed to one of said first or second pipe element, by inflation of a said second chamber which is pressed against the internal wall of the sleeve in its main part, said first chamber being arranged opposite a free end part of said sleeve,

a.3) the first chamber is inflated which is pressed against the end part of said sleeve, and

b) after or before step a.3), the two pipe elements are assembled by introducing and forcibly inserting the part of a sleeve forming a said male end of a pipe element into the end female without the sleeve of the other pipe element,

c) said metal welding of the ends of the two pipe elements end to end is carried out, and

d) sending a said laser beam, by simultaneously exerting a pressure of said sleeve end part against said sleeve end part in contact with one another by inflating said first chamber to produce a said laser welding zone , and

e) the first chamber is deflated and a control laser beam is sent to the weld area.

More particularly still, before step a), steps ii) to i.6) of the method of placing a tubular junction sleeve are carried out at one end of a unitary pipe element according to l The invention, preferably on the deck of the ship or on land, for fixing a said sleeve in the terminal part of a said pipe element before its assembly with another said pipe element.

The term “internal” and “external” is understood here to mean, internal and respectively external to the pipe, to the sleeve or to the lining as the case may be.

It is understood that the term “running part of the sleeve” here means the central part of the sleeve situated between the two end parts at the two longitudinal ends of the sleeve.

More particularly, the pipe to be produced is a connecting pipe either resting on the seabed, or a bottom / surface connection suitable for being laid in an underwater environment, and said pipe elements have a length of 20 to 50 m , with an internal diameter of 10 to 60 cm and said sleeve has a length of 45 to 150 cm. It is more particularly a pipe for injecting pressurized water into oil field wells, which pressure is always greater than 5 MPa and more particularly 25 to 70 MPa (250 to 700 bars). This type of pipe as mentioned above is particularly stressed at said metal welds so that they must be protected as much as possible from any corrosion by contact with sea water, especially in the case of bottom-surface connections, because in this case the pipe is perpetually in motion owing to the effects of the swell of the wind and of the current exerted on the support floating on the surface and therefore subjected to extreme fatigue stresses. In addition, the properties of the fluid conveyed can lead to having to include significant sacrificial steel excess, having a strong impact on the installation of these pipes. The installation of a plastic liner eliminates this need.

Other features and advantages of the present invention will become apparent in the light of the detailed description which follows, with reference to the following figures.

• Figure 1 is a side view of the assembly of a pipe according to the invention, using a tubular junction sleeve between two pipe elements or unit lengths of lined pipes according to the invention with tapered end portions of sleeve and liner.

• Figure IA is a sectional side view of the frustoconical end 2a of the internal liner 2 of a pipe element of Figure 1, schematically the traces of weld areas 3 on said frustoconical contact surface 2-1.

• Figure 2 is a sectional side view of the tubular junction sleeve having two ends of the cylindrical type.

• Figure 2A is a side view section of a steel pipe 10 equipped with an internal liner 2 machined along a female cylinder of axis XX 'of internal radius Ri and receiving a tubular sleeve according to Figure 2, machined along a male cylinder of axis XX 'of substantially identical external radius Ri.

• Figure 3 is a sectional side view of a tubular junction sleeve having two straight front ends of planar annular type.

• Figure 3A is a sectional side view of a steel pipe equipped with an internal liner machined in a plane perpendicular to the axis XX 'at a distance L2 from the end of said pipe, and receiving a sleeve tubular according to the configuration of figure 3.

• Figure 4 a side view section of the assembly of a pipe according to the invention, using a tubular junction sleeve between two pipe elements or unit lengths of lined pipes according to the invention, with overlapping cylindrical sleeve and liner end portions.

• FIG. 5 schematically represents an embodiment of said means of rotation R of the mirror combined with the means of relative translation of said mirror in a device according to FIG. 4.

• Figure 6A is a longitudinal sectional view at the junction of two tubes showing laser welding with a device 20 for producing an assembly method according to the invention, involving a rotation of an inclined mirror (β ) around the longitudinal axis XX 'of said tubes, combined with a relative translation of said mirror in the coaxial direction XX'.

• Figure 6B is a longitudinal sectional view at the junction of two tubes overlapping by contact at the frustoconical end contact surface showing the laser welding with a device 20 for performing an assembly method according to the invention, involving a rotation of a mirror around the longitudinal axis XX 'of said tubes, combined with a variable inclination of the surface 4a of the mirror by a variable angle β.

• Figure 7 shows the production of a liner tube by butt assembly of large lengths of absorbent liner tubes 2 and small lengths of transparent liner tubes 1.

• Figure 8 shows details of laser welding at the level of annular planar surfaces applied one against the other end to end of said absorbent tubes and transparent tubes.

• Figure 9 schematically shows an embodiment in which a transparent sleeve tube 1 is placed inside an absorbent tube 2 for lining a pipe 10, schematically showing a helical weld zone 3h between the transparent tube 1 and the absorbent tube 2, said laser welding being carried out from inside the transparent tube 1.

• Figure 10 shows a side view of an installation vessel equipped with a so-called J-laying tower.

• Figures 11 to 15 show different steps of positioning and laser welding of the sleeve 1 at one end of a pipe element with a device according to the present invention shown schematically.

• Figures 16 to 22 show different stages of assembly of two pipe elements with installation and welding of the sleeve 1 at one end of a first pipe element at the end without the sleeve of a second element driving with a device according to the present invention shown schematically.

• Figures 23 and 24 show a device 20 for placing a sleeve comprising two chambers capable of performing laser welding.

In Figure IA, there is shown a pipe 10 according to the invention comprising at least 2 pipe elements 10ι, IO2 with internal lining 2 in polyethylene or polypropylene assembled end to end, in which the ends of the two pipe elements are welded 11 to each other. Each pipe element comprises an internal lining of thermoplastic material 2 of axis XX 'coinciding substantially with the axis of the pipe elements 10i, IO2, having at each end a conical end part 2a with a half-angle at the top a of 5 to 15 °, in particular 10 °, of reduced thickness compared to the thickness of the main part 2b of said sleeve, defining a concave shape with a frustoconical internal surface of revolution comprising a contact surface 2-1 of internal diameter greater than that of the running part 2b of said sleeve and terminating at a certain distance L from each end of said pipe element. The outer surface of each said end part 2a of the inner liner is optionally locked by gluing 2c of the end of the liner at or near said end part of reduced thickness 2a of the liner against the corresponding inner surface of the steel wall of the pipe, using an adhesive, preferably of the polyurethane or two-component epoxy type.

A tubular junction sleeve 1 made of thermoplastic material, preferably identical to the thermoplastic material of the internal lining 2, of axis XX 'coinciding substantially with the axis of the pipe elements 10ι, IO2, of the same external diameter, just slightly less than the diameter internal of the pipe, is inserted inside each of the end-to-end ends of the two pipe elements, so as to overlap said end parts of the two liners by means of a device 20 according to the invention as described below. -after with reference to Figures 11 to 19.

Said sleeve 1 has at each longitudinal end a transparent terminal portion of reduced thickness with respect to the thickness of the adjacent running portion lb of said sleeve, said end portion la of the sleeve defining a convex shape capable of overlapping the opaque end portion d reduced thickness of said lining 2a with which it is in contact. Said end part 1a of the sleeve defines a frustoconical outer surface 1-1 with an outer diameter smaller than that of the adjacent running part lb of the sleeve, having the same angle at the apex a as said tapered inner surface of said concave end part of said liner. The end portions of the conically shaped sleeve define an internal cylindrical surface 1-2 substantially of the same internal diameter as that of said running part 2b of the liner and running part 1b of the sleeve.

In Figure 1, the sleeve has in a central part 1c, that is to say approximately halfway in its axial longitudinal direction XX ', a reduced external diameter smaller than the external diameters of its running parts 1b adjacent to said. central part 1c so as to provide an annular space 12, and an annular part 13 for thermal protection of the sleeve is placed during welding of the ends of the pipe elements, said running parts 1b of the sleeve having an external diameter substantially identical to the internal diameter of the uncovered ends of said lining of the assembled pipe elements.

The tubular wall of said sleeve has a substantially constant thickness in its central part le and its adjacent running parts lb, and substantially equal to the thickness of the running part 2b of said internal liner 2, and said central part of the sleeve is able to fit. deform to adopt an internal diameter substantially identical to the internal diameter of the rest of the sleeve under the effect of an internal pressure of the fluid circulating inside the pipe in operation of at least 1 MPa, and the thermal protection part 13 is itself also deformable under the same internal pressure conditions inside the pipe to adopt a reduced thickness, preferably a thickness of less than 5 mm, more preferably less than 2 mm, said thermal protection piece being of more preferably made of ceramic fibers in a form similar to cotton wool.

We understand that:

- the central part of the sleeve due to its substantially constant thickness, has a reduction in the external diameter as well as the internal diameter during installation, the pipe being empty and at atmospheric pressure and when it is subjected to pressures corresponding to pressure values less than 1 MPa (10 bars),

- as soon as the internal pressure exceeds 1 MPa (10 bars), the thicknesses in particular of the order of 3 to 10 mm and the rigidity of the plastic material such as polyethylene or polypropylene allow an increase in the internal and external diameters of the central part by deformation, for example when circulating inside the pipe and the sleeve a fluid, in particular pressurized water, as is the case in water injection pipes for oil wells greater than 5 MPa , in particular from 25 to 70 MPa.

Due to the fact that the pressure Po on the outside is much lower than the internal pressure Pmax, the latter has the effect of pressing in an energetic manner the constricted central part of the tubular junction sleeve 1 against the wall of the steel pipe, the ceramic fiber screen 13 also being crushed and then only having a residual thickness of no more than 1 to 2 mm.

A laser device such as manufactured and marketed by the company TRUMPF (FRANCE) can be used.

In FIG. 1A, there is schematically shown a plurality of traces 3 of laser welding zones which may correspond to a plurality of circular weld zones arranged side by side in a discontinuous and parallel manner, when moving step by step the mirror 4 in relative translation as described below or which may correspond to a continuous weld zone in the form of a spiral with turns of increasing diameters.

In FIGS. 2 and 2A, said internal surface of the terminal portion of reduced thickness 2a of the liner and external surface of the terminal portion of reduced thickness 1a of the sleeve, in contact with each other, are of the same cylindrical shape. having the same axis XX 'as said sleeve and said pipe, the end of the terminal portion of reduced thickness of the sleeve abutting against a shoulder 2e delimiting the internal surfaces of said running part 2b and end portion of reduced thickness 2a of the liner .

In FIG. 2A, the internal liner has been machined with a cylindrical shape of axis X'X and radius R over a length L ₃ and at a distance L ₄ from the end of said pipe.

In this embodiment with a cylindrical contact surface, said sleeve is inserted against the end portion of reduced thickness 2a of the liner until the end 2f of the liner abuts against a shoulder delimiting said running part lb of the sleeve. and said thinner end portion la of the sleeve, and / or said sleeve is inserted against the reduced thickness end portion 2a of the liner until the end lf of the sleeve abuts against the shoulder 2e delimiting the main part 2b and said end part 2a of reduced thickness of the liner.

As a reminder and as described in WO 2006/042925, the end lining parts are produced at the end of the insertion process by “swagelining” and if necessary gluing, the sleeve then being cut flush with the steel pipe element. , then the machining is carried out by a machining machine installed on the face of the first end of the pipe element.

In FIG. 3A, a plane machining has been carried out perpendicular to the axis XX ′ located at a distance L2 from the end of said pipe.

Several modes of assembly between the internal liners and the tubular junction sleeves are possible and each have an advantage with respect to the thickness of the internal liner 2. The value of the angle a between the axis XX 'and the generatrix of the surface of the end part 1a of the sleeve in contact with the end part 2a of the liner can vary from 0 to 90 °. For the embodiments of Figures 2 and 3, showing an end part 1a of conical convex shape, the conical outer surface has a half-angle at the top a of between 0 and 90 °, the top of the cone being on the left of the figure.

In Figure 3, there is shown a so-called front shape: it is in fact a shape equivalent to the conical shape, in which the angle a 'is equal to 90 °.

In FIG. 2, a cylindrical shape has been shown: it is in fact an equivalent shape in conical form, in which the apex angle a is equal to 0 °, the apex of the fictitious cone are then at infinity.

In the case of thin liners, for example 3 to 5 mm, the conical mode of FIGS. 1 and IA will advantageously be used with an angle α of between 5 ° and 45 °, preferably 10 °. For medium thicknesses, for example 6 to 12 mm, the cylindrical mode of FIG. 2 will advantageously be used. For large thicknesses, for example 12 to 20 mm, the frontal mode of the cross section of FIG. 3 will advantageously be used.

In the case of prefabrication in the workshop, the operational conditions are much simpler than on site, and moreover the hourly cost of the laying vessel is not involved. It may therefore be necessary to prepare tubular junction sleeves and trainsets with assembly technologies different from those used on site. To this end, in FIG. 3A, there is detailed a tubular junction sleeve of the mixed type, having, on the right an end of the front type which will be assembled in the workshop on the corresponding front end of an internal train liner such as as described with reference to Figure 3A.

In FIG. 1, only part of the means of an assembly device by laser welding according to the invention has been shown comprising a 3d laser device disposed outside the tubes 1, 2 and joining a head via an umbilical 3c. laser 3b supported by an assembly device 20 (not shown). Said laser head 3b emits a beam of axial laser beam 3a-1 XX ', the latter being deflected by reflection on the surface 4a of the mirror 4, inclined at an angle B of 45 ° with respect to the axial direction XX' . The ray 3a-2 reflected on the surface 4a arrives on the tapered contact surfaces 1-1 and 2-1 inclined, said ray being inclined at an angle 02 of 90 ° - a with respect to said surfaces 1-1 and 2 -1 (and an angle ai = a with respect to the perpendicular to said contact surfaces 1-1 and 2-1).

A control laser beam 3a-3 reflected on the weld zone is analyzed by a receiver 3r comprising a sensor capable of measuring the power absorbed so as to check the quality of the weld, when, as explained previously, the beam sent 3a 1, 3a-2 is a lower energy welding control laser beam than the welding laser beam.

In Figure 5, there is shown a part of an assembly device 20 by laser welding according to the present invention, comprising a mandrel 20a disposed in the same longitudinal axis XX 'as the axis of the tubes 1 and 2 to the. inside which it is inserted, the mandrel 20a supporting a laser head 3b arranged axially, emitting laser radiation 3a-1 in the longitudinal direction XX '. The mandrel 20a supports at the front a first inflatable chamber 21, consisting of two fixed hoops 21-b arranged transversely with respect to the longitudinal axis XX 'of said first chamber and of said tubes, spaced from one another in the direction XX ', the two hoops being connected to one another by a flexible transparent silicone envelope 21a. Inside the chamber 21 is positioned a mirror 4, the reflecting surface 4a of which is inclined at an angle 6 of about 45 ° so that the laser radiation 3a-1 is deflected 90 ° in the transverse direction. The ray 3a-2 reflected on the mirror arrives at a point of incidence 3i at the level of the frustoconical contact surface 2-1 of the bevelled reduced thickness end 2a of the absorbent tube 2, after passing through the end d The reduced thickness 1a of the transparent tube 1. The heat of fusion of the contact surface 2-1 is transmitted by thermal conduction at the level of the contact surface 1-1 in a localized manner at the level of the interface contact with the points d impact 3i of the radiation 3-2 on the contact surface 2-1.

In Figure 4, there is shown an embodiment in which the internal liner and the sleeve are of low thickness of not more than 5 mm with unmachined end parts of the same thickness as the adjacent running parts of the liner and sleeve respectively. . The internal liner and sleeve end portions are superimposed without abutting against each other with cylindrical 1-1 and 2-1 contact surfaces joined by a continuous cylindrical weld area 3.

In FIG. 6A are schematically represented means of relative translation T of the mirror inside the fixed chamber 21. The chamber 21 is fixed by inflating and applying pressure at the cylindrical inner surfaces 1-2 of the tube 1 at the reduced thickness end portion 1a. The translation T of the mirror makes it possible to move the point of incidence spaced 3i from 3i-l to 3i-3 of the radius 3a-l and to create the weld zone 3 at the level of the frustoconical contact surfaces 2-1 and 1-1 as shown in figure 5.

In FIG. 5, there is shown in more detail but schematically, the means of rotation R of the mirror 4 with respect to the longitudinal axis XX 'of the tubes and means of relative translation T of the mirror with respect to the device 20, which are included in the transparent inflation chamber 21, not shown in FIG. 5. The mandrel 20a supports a motor 20b which drives in rotation a gear system driving the rotation R of the mirror 4 around the longitudinal axis XX '. More precisely, the motor 20b drives the pinion 20c in rotation, which drives a toothed wheel 19a in rotation with respect to the same longitudinal axis XX ', integral with a rotating structure 19 comprising said mirror and therefore allowing the rotation of said mirror around the same. 'axis XX' thanks to a ball bearing system 19c.

In Figure 5, it has been indicated that the mandrel 20a can support either the laser head 3b or directly a 3d laser device.

On the other hand, in Figure 5, there is shown an embodiment in which the rotation R of the mirror 4 relative to the longitudinal axis XX 'of said tubes is combined with a continuous relative translation T in a direction longitudinal to l using a worm 18 operating as follows. The toothed wheel 19a drives in rotation along the same longitudinal axis XX ′ a second toothed wheel 19b which cooperates with a pinion 18b driving the worm 18 in rotation along a longitudinal axis XiXf via a longitudinal shaft 18a. The worm 18 cooperates with a mirror support 4b such that the rotation of the worm 18 around its axis XiX'i causes the relative translational movement of the support 4b of the mirror 4. The translation of the mirror 4 is therefore ensured by the endless screw 18 slaved to the rotation R, for example at a rate of 3 mm / turn, one turn corresponding to a screw pitch of a 3h helical weld zone thus obtained. It is understood that the pinion 18b and the worm 18 form part of the rotating structure driven in rotation about the axis XX 'with the support 4b and the mirror 4.

In an alternative embodiment (not shown), it is possible to implement, instead of a worm 18, a relative translation system step by step and not continuously, so that the rotation of the pinion 18b triggers a discontinuous movement and which makes it possible to obtain parallel circular weld zones arranged side by side and spaced apart by a translational step in the longitudinal direction XX 'instead of a continuous weld zone in the form of a spiral or helical.

The implementation of a continuous or step-by-step translation with translation steps corresponding to the width of the weld zone created by the width of the radius makes it possible to obtain a weld zone 3 extending over a surface of revolution continues along the longitudinal direction of translation as shown in Figure 4.

In FIG. 6B, there is shown an embodiment according to which, instead of a relative translation T of the mirror 4 inside the inflation chamber 21, the angle of inclination 8 of the surface is varied. 4a of the mirror 4, so that the reflected radiation 3a-2 deflected by the surface 4a of the mirror arrives on the contact surfaces 1-1 and 2-1 at an inclination ai of 0 ° to 30 ° with respect to the perpendicular to the say contact surfaces 1-1 and 2-1. The point of incidence 3i-1 corresponds to an inclination ai of 0 °, point 3i-2 to an inclination ai of 10 °, and point 3i-3 to an inclination ai of 30 °. The relative tilting means of the mirror 4a can be slaved to the rotation R of the mirror about the axis XX 'by equivalent means involving the use of a gear and worm system 18. For example , we will implement a worm 18 meshing on an angular gear system with an output pinion of an axis perpendicular to the axis of the worm 18 and which cooperates with a pinion of the support of the mirror causing the inclination of the mirror slaved to the rotation of the mirror around the longitudinal axis XX 'of said tubes. The worm 18 can be driven in rotation in the same way as in the embodiment of FIG. 5. For example, a variation of the inclination of the angle 8 of the surface 4a of the mirror with respect to the mirror is produced. 'axis XX' of ± 5 °, said variation in inclination being slaved to the rotation R of the mirror, at a rate of 0.5 ° / turn to obtain a weld zone in the form of a spiral or helical 3h. Alternatively, a plurality of parallel circular weld zones can be produced here again side by side by virtue of discontinuous inclination variations, obtained by the implementation of a spring and cam system making it possible to actuate an angular triggering lug. step by step of said inclination, for example 0.5 ° / step.

The method according to the invention makes it possible to obtain weld zones of perfect quality and extremely strong with a weld width corresponding to the width of the laser beam of 2 to 3 mm in the axis XX ', making it possible to weld thicknesses tubes up to 25 mm thick, and more particularly 1 to 25 mm thick. It is thus possible to produce a weld zone extending in the axial direction by means of a helical zone made of a plurality of discontinuous circles side by side, spaced every 5 mm for example, and together extending over a distance of 20 to 50 mm in the direction of XX '.

In FIG. 7, there is shown an exemplary embodiment of the assembly of absorbent tubes 2 of great length and transparent tubes 1 of short length end to end at the level of end-to-end planar annular surfaces extending in planes perpendicular to each other. their longitudinal axis XX '.

In Figure 8, there is shown an embodiment of a plurality of concentric circular weld zones 3-1, 3-2 and 3-3 by inclination of a variable angle 8 of the surface 4a of the mirror 4 with respect to to the longitudinal axis XX 'of the tubes 1 and 2. The variation of the angle 8 implies a variation of the angles ai and 02 of the incident ray 3a-2, ai with respect to the longitudinal axis XX' itself perpendicular to the flat front contact surfaces 1-1 and 2-1, and 02 with respect to the flat front contact surfaces 1-1 and 2-1 perpendicular to the axis XX '. Due to the plurality of circular weld zones 3-1, 3-2, 3-3, a weld extending over 60-90% of the thickness of the tubes 1 and 2 is thus produced.

In Figure 9, there is shown an embodiment, in which the transparent tube or sleeve 1 is placed inside the opaque absorbent tube or liner 2 of a pipe 10 to which it must be assembled by laser welding at the level of their non-machined cylindrical ends or end parts 1a, 2a of constant thickness, preferably not more than 5 mm, superimposed and overlapping over a distance I = 2 to 5 mm. And, a continuous helical weld zone 3h was produced using a device with a laser beam rotating around and with respect to the axis XX 'inside the transparent tube 1, so that the laser beam first passes through the inner transparent part before being reflected on the outer absorbent part. In this embodiment, the weld zone has turns of constant diameter because said contact surfaces are cylindrical.

On the other hand, in one embodiment, in which the contact surfaces 1-1 and 1-2 are frustoconical surfaces of revolution as shown in FIGS. 4 and 6, the weld zone is in the form of spirals with turns. of increasing diameters, from the turn passing through point 3i-l corresponding to the turn of smaller diameter, to point 3i-3 corresponding to the turn of larger diameter, the envelope surfaces of said weld zones are then frustoconical and not cylindrical surfaces.

In FIGS. 10 to 15, the various stages of placing a tubular junction sleeve 1 are shown at the level of one end of a pipe element 10i using a device 20 for placing sleeve. These operations can be carried out on land or on the deck of the ship 100 in a horizontal position.

A device 20 for placing the sleeve 1 according to the invention is equipped in Figures 11 to 15 with a mandrel 20a of cylindrical shape extending in an axial longitudinal direction XX 'comprising a longitudinal cylindrical central orifice within which is disposed an umbilical 20d which also serves as the handling wire of the device 20.

In FIGS. 10 to 21, the device 20 comprises a first inflatable chamber 21 with transparent wall 21a, equipped with mirror 4 and means for rotating the mirror in translation and / or inclination as described above, said first chamber being arranged in the longitudinal direction XX 'at a distance d from a second inflatable chamber 22.

The first and second chambers are spaced apart by a distance d such that when the second chamber 22 is disposed opposite the restricted central part of the sleeve, the first chamber 21 is disposed opposite. from one end of the sleeve at its terminal portion of reduced thickness 1a.

In FIGS. 11 and 12, a device for placing the sleeve 20 according to the present invention has been inserted such that, as shown in the figure, when the second inflatable chamber 22 is inflated to the maximum, the latter comes to be pressed against the wall of the restricted central part 1b of the sleeve 1. The assembly of the device 20 and of the sleeve 1 is thus secured and can be moved in horizontal translation towards the open end without the sleeve of an element of pipe 10t, until it abuts against the end 2a of the liner 2 of the pipe element li as shown in Figure 13. At this time, as shown in Figure 14, the transparent wall 21a of the first inflatable chamber 21 is disposed opposite the frustoconical contact surfaces 1-1, 1-2 at one end of the sleeve, as shown in Figures 13 and 14. At this stage, the first inflatable chamber 21 can be inflated in such a way. to come and tackle the game ended the la of the sleeve in abutment against the end 2a of the liner and the laser beam 3a is sent which melts the area of the contact surfaces 1-1, 2-1 of the sleeve 1 and of the liner 2, and thus makes it possible to achieve a laser fusion welding of the zone of the contact plane between the tubular junction sleeve 1 at its end 1a and the end 2a of the sleeve 2 through which the laser beam 3a passes as described above. The first chamber 21 is expanded with a pressure which makes it possible to guarantee excellent compactness in the fusion plane as well as the absence of air bubbles detrimental to good sealing at the level of the fusion surface.

Then, to carry out the weld quality control steps, the first chamber 21 is deflated in the deflated position which remains relatively close to the walls of the sleeve and a control laser beam is sent to the weld area, the ray of which is analyzed. reflected on the weld zone using a 3r sensor located in the first chamber.

Once the weld control has been carried out, the device 20 can be evacuated in translation after having first deflated all the inflatable chambers. Said first and second inflatable chambers 21 and 22, in the deflated position, remain relatively close to the walls of the sleeve so that the guiding of the device 20 in longitudinal translation inside the sleeve can be done easily. Advantageously, this guidance can be carried out manually or by a carriage or other guiding means in longitudinal translation.

Thus, there is ready to be fitted a pipe element 10i equipped at one of its ends with a tubular junction sleeve 1 forming a male part ready to be fitted into the female part without a tubular junction sleeve of a second element. driving.

In FIGS. 16 to 22, there is shown the assembly between two unit lengths of jacketed pipe, during the on-site installation which is carried out on board a laying vessel 100 equipped with a J-shaped laying tower 100a , as shown in Figure 10. A new duct element 10i fitted with a tubular sleeve 1 at one of its ends is transferred, in known manner, from the horizontal position to the oblique position corresponding to the inclination of the tower to then be positioned in the axis of the terminal pipe element IO2 of the end of the train being laid. Said pipe element to be assembled 10i is then moved axially towards the end pipe element 10 ₂ in suspension. A sleeve part 1 forming a male end of one of the two pipe elements penetrates into the female end without the sleeve of the other pipe element to be assembled, until the end part 1a of the sleeve comes in. contact with the end part 2a of the sleeve 2 inside the other pipe element 10i. The two pipe elements being close to the vertical, a manipulator arm allows the end part 1a of the sleeve to fit completely against the end part of the sleeve to achieve the configuration of Figure 23 where the two pipe elements 10i, IO2 are maintained at a distance of a few mm, for example by means of this same manipulator arm, not shown, so as to be able to perform, in a known manner, the weld 11 by means of an orbital welding robot known to those skilled in the art. art. In the figures, there is shown the walls of the chamfered steel pipes spaced a few mm apart during welding, the screen 13 consisting of a ceramic foam mattress limits the heat transfer and protects the thermoplastic sleeve throughout the process. welding. And, in the right part, the weld 11 is shown completed.

In one embodiment shown in Figures 16 to 22, a new terminal pipe element 10i is equipped with a tubular junction sleeve 1 at its lower end thus forming a male end descending towards the upper female end of a first pipe element 10i without a sleeve forming the upper terminal pipe element of a pipe in the course of installation held fixedly in suspension at the base of the tower.

In a first step, the sleeve positioning device 20 is lowered by the umbilical 20d so that the first inflatable chamber 21 is positioned opposite the end part 1a of the lower end of the sleeve 1. and the terminal part la. Thus, the second inflatable chamber 22 is located opposite the central part of the sleeve 1, as shown in FIG. 17. At this time, the second chamber 22 is inflated so as to secure the device 20 with the sleeve 1. , the device 20 now being lowered with the pipe element 10i until the male end of the sleeve protruding from the end of the pipe element 10i is embedded inside the unsheathed female part of the element IO2 pipe, so that the end part 1a of the sleeve 1 abuts against the end part 2a of the liner 2 of the IO2 pipe element as shown in Figure 19.

At this stage, FIG. 20, to carry out the fusion by laser welding, the first inflatable chamber 21 is inflated, and the laser radiation is sent so as to carry out the fusion at the level of a weld zone 3 between the end parts 1a of the sleeve 1 and end part 2a of the liner 2, the optical fiber being routed in a conduit inside the umbilical 20d.

Then, to carry out the control of the weld by control by control laser beam, the two chambers 21 and 22 are partially deflated. Then, the various inflatable walls, 21, 22, can be deflated and the device 20 can be reassembled for a subsequent setting implemented by assembling a new pipe element.

In Figures 23 and 24, there is shown an embodiment in which the two chambers 21 and 22 are equipped with transparent walls, placed in such a way that they can be positioned simultaneously with regard to the two ends 1a of the same sleeve. 1, the set of the two chambers 21 and 22 being of a length greater than the sleeve 1 so that the two chambers can coincide and press against the two ends of the sleeve simultaneously.

Alternatively, it is possible to descend a new pipe element IO2 already equipped with a tubular junction sleeve 1 at its upper end, but the lower end of which without a sleeve thus forms a female end of said new pipe element lowered towards the end. male upper of a first pipe element 10i equipped with a tubular junction sleeve 1 at its upper end, this first pipe element 10i forming the upper terminal pipe element of a pipe in the course of installation held fixedly in suspension at the bottom of the tower.

Claims (24)

1. Method of producing the assembly of tubes in thermoplastic materials, in which at least two tubes (1, 2) arranged end to end or overlapping at least in part coaxially, in which said assembly is carried out by laser welding of two contact surfaces of revolution (1-1, 2-1) applied one against the other of respectively two parts (la, 2a) of two tubes (1, 2), comprising at least: - an end terminal part (la) of a first tube (1), transparent to the wavelength of the laser, and - an end terminal part (2a) of the second tube (2), absorbing at the wavelength of the laser, and said welding being carried out using a laser beam (3a, 3a-2) that l 'a laser device (3d) or a head of the laser device (3b) emitting is moved in rotation (R) at 360 ° relative to the common longitudinal axis (XX') of the first and second tubes (1,2) said laser beam (3a), being disposed inside one of said first and second tubes (1, 2) such that said laser beam (3a, 3a-2) first passes through said part transparent end (la) of the first tube (1) to reach an area of said contact surface of revolution (2-1) of the absorbent end part (2a) of the second tube (2) and, preferably, pressure is applied on said contact surfaces against each other, to achieve a weld zone (3) by fusion between said contact surface of revolution (1-1) of the transparent part (la) of the first tube (1) and said part you absorbent end of the second tube, characterized in that said first tube is a tubular junction sleeve (1) made of thermoplastic material inserted inside a pipe (10) comprising at least two steel pipe elements (10-1 , 10-2), the two pipe elements (10-1, ΙΟΣ) each comprising an internal lining tube of plastic material each constituting a said second tube (2), said tubular junction sleeve (1) being inserted at the level of the butt assembly of the unsheathed ends of the two pipe elements which are metallically welded or intended to be metallically welded (11) to each other, said end parts of the sleeve and of the liner being in contact with one another with the other, at the level of external surfaces of revolution of said end portions of the sleeve in contact with internal surfaces of revolution of said liners, said surfaces of revolution of said end portions of the sleeve and of the sleeve having the same axis of revolution as said pipe and overlapping in the axial direction, and said welding is preferably carried out by applying a said pressure on the internal surface (1-2) of said sleeve in the radial direction at the level of said surfaces of revolution in contact . 2. Method according to claim 1, characterized in that said internal liner (2) and said sleeve (1) have a thickness less than or equal to 5 mm, preferably 3 to 5 mm. 3. Method according to claim 1 or 2, characterized in that: - said internal lining (2) has at least one end an end part (2a) of the same thickness (2a) as the thickness of the running part (2b) of said lining, defining a cylindrical internal surface corresponding to a said surface of contact (2-1), of the same internal diameter as that of the internal surface of the running part (2b) of said liner, and - said sleeve has at least one end an end part (la) of the same thickness as the thickness of the adjacent running part (lb) of said sleeve, said end part (la) of the sleeve defining: - a cylindrical outer surface corresponding to a said contact surface of revolution (1-1), of external diameter substantially identical to that of the internal surface of said liner and - a cylindrical internal surface (1-2) of internal diameter smaller than that of the internal surface of said liner, - said end part (la) of the sleeve thus being able to overlap in a superimposed manner the end part of said lining (2a) with which it is in contact, and - Laser welding of said internal cylindrical surface constituting a said contact surface (2 * 1) of said liner and of said cylindrical external surface constituting a said contact surface (1-1) of said sleeve. 4. Method according to one of claims 1 or 2, characterized in that: - said internal liner (2) has at least one end an end portion of reduced thickness (2a) relative to the thickness of the running part (2b) of said liner, defining a concave shape with an inner surface forming a said contact surface of revolution (2-1), preferably frustoconical or cylindrical, with an internal diameter greater than that of the internal surface of the running part (2b) of said lining, and - said sleeve has at least one end an end part (la) of reduced thickness compared to the thickness of the adjacent running part (lb) of said sleeve, said end part (la) of the sleeve defining a convex shape capable of overlap and abut against the reduced-thickness concave end portion of said liner (2a) with which it is in contact, said end portion (la) of the sleeve defining an outer surface corresponding to said rotational contact surface (1-1) , preferably frustoconical or cylindrical, of external diameter smaller than that of the adjacent running part (lb) of the sleeve and a cylindrical inner surface (1-2) substantially of the same internal diameter as that of the running part (2b) of the liner and part current (lb) of the sleeve, and - The laser welding of said internal surface of revolution constituting a said contact surface (2-1) of said liner and of said external surface of revolution constituting a said contact surface (1-1) of said sleeve is carried out. 5. Method according to one of claims 1 to 4, characterized in that one carries out a weld zone (3) continuous in the form of a spiral or helical (3h) or a plurality of circular weld zones concentric or arranged side by side. parallel side (3-1, 3-2, 3-3) along the axial direction of said contact surfaces (1-1, 2-1). 6. Method according to one of claims 1 to 5, characterized in that the laser head (3b) is arranged so as to emit a said laser beam in a longitudinal direction of said first and second tubes (1, 2) in screw. -to a mirror (4), preferably the axial direction (XX '), so that said laser beam (3a-l) emitted by the laser head (3b) is reflected (3a-2) on the surface (4a) of the mirror (4), the surface (4a) of the mirror (4) being inclined at an angle (β) with respect to the longitudinal axis (XX ') of said tubes, preferably at an angle (β) from 30 to 60 °, preferably 45 °, and said inclined mirror is mounted capable of pivoting (R) through 360 ° as well as said laser beam reflected (3a-2) by the rotating mirror (R) relative to to the longitudinal axis (XX ') of said tubes. 7. Method according to claim 6, characterized in that said mirror is mounted capable of being further moved in translation (T) longitudinal axial (XX ') and a said translational movement of said mirror is carried out in combination with a said rotation ( R) of said mirror over 360 ° relative to said longitudinal axis (XX ') of said tubes. 8. Method according to one of claims 6 or 7, characterized in that the surface (4a) of said mirror (4) is mounted capable of being inclined at an inclination (β) variable relative to the longitudinal direction (XX ') said tubes (1, 2) and the angle (β) of said inclination of the surface (4a) of the mirror (4) with respect to said longitudinal direction (XX ') is varied in combination with a said rotation (R) of said mirror (4) relative to said longitudinal axis (XX '). 9. Method according to one of claims 1 to 8, characterized in that said inner lining tube is obtained by assembly by laser butt welding, alternately, of small lengths of first transparent lining tubes (1) and long lengths of second absorbent liner tubes (2), by sending against the end end face annular surfaces (1-1, 2-1) of said first and second liner tubes in end-to-end contact, from a laser head inside at least one of said tubes, a laser beam (3a) inclined relative to the coaxial longitudinal axis (XX ') of said tubes, said end frontal planar annular surfaces (1-1, 2- 1) being perpendicular to the axis (XX ') of the two first and second liner tubes, and preferably covers the short lengths of the first transparent liner tubes with a coating of the color of said second absorbent liner tubes. 10. Method according to claims 8 and 9, characterized in that a variation of said inclination is carried out by step-by-step angular displacement of said mirror successively at a said rotation (R) of said mirror over 360 ° relative to the longitudinal axis. (XX '), said laser welding being carried out during a said rotation (R) of the mirror through 360 ° relative to the longitudinal axis (XX') of said tubes to produce a plurality of circular weld zones in the form of concentric circles ( 3-1, 3-2, 3-3). 11. Method according to one of claims 1 to 8, characterized in that one assembles by laser welding transparent end parts and absorbent end parts of first and second coaxial tubes (1, 2), said parts. transparent and respectively absorbent ends of the two tubes overlapping at said contact surfaces of revolution (1-1, 2-1) with respect to the longitudinal axis (XX ') of said coaxial tubes and it is sent from a laser head inside at least one of said tubes, a laser beam (3a, 3a-2) on said contact surfaces, said beam (aser being perpendicular to said contact surfaces or inclined (ai), of preferably within a range of 0 to 30 °, relative to the perpendicular to said contact surfaces (1-1, 1-2). 12. Method according to claim 11, characterized in that said contact surfaces of revolution (1-1, 1-2) of said first and second tubes (1, 2) to be welded overlapping are of cylindrical or frustoconical shape with the same axis. than the longitudinal axis (XX ') of said tubes. 13. Method according to claim 11 and one of claims 7 or 8, characterized in that a said continuous translation or said continuous inclination is carried out concomitantly with a said rotation (R) of the mirror over 360 ° with respect to the longitudinal axis (XX ') of said tubes, and a so-called helical weld zone is obtained on said cylindrical contact surfaces (1-1, 2-1) or a said spiral-shaped weld zone with turns of increasing diameters on said frustoconical contact surfaces. 14. Method according to claim 13, characterized in that a said step-by-step translation or a said inclination is carried out by step-by-step angular displacement of said mirror with respect to the longitudinal axis (XX ') of said tubes, said inclination being carried out successively at a said rotation (R) of said mirror over 360 ° relative to the longitudinal axis (XX ') of said tubes by performing said laser welding during said rotation to produce a plurality of circular zones (3-1, 3 -2, 3-3) side by side, of the same diameter on said cylindrical contact surfaces (1-1, 2-1) or of increasing diameters on said frustoconical contact surfaces (1-1, 2-1). 15. Method according to one of claims 1 to 14, characterized in that said laser welding is carried out by sending an energy ray of 1 to 5 W / mm ² , preferably 2 to 3 W / mm ² . 16. Method according to one of claims 6 to 15, characterized in that said rotations (R) of the mirror are carried out over 360 ° relative to the longitudinal axis (XX ') of said tubes at a speed of 10 turns / seconds around / 10 seconds. 17. Method according to one of claims 1 to 16, characterized in that a control of the quality of the laser weld is carried out by sending a control laser beam to said weld zone, preferably emitted with the same device ( 3b, 3d) and under the same conditions of rotation, translation or inclination as the welding beam, and by analyzing using a sensor (3r), preferably by absorption measurement, a control laser beam reflected on the welding zone, said control laser beam having an energy lower than said welding laser beam, preferably an energy of 0.01 to 0.05 W / mm ² , and preferably said control laser beam being of frequency identical to that of the beam laser welding. 18. Device (20) for implementing a method according to one of claims 1 to 17 comprising: - a mechanical system (20a) supporting a mirror (4) and a said laser head (3b) connected to an umbilical (3c), able to adapt and be moved inside said first and second tubes to be assembled, and - forced radial extension means (21, 22) capable of resting against the internal surface (1-2, 2-2) of one of said first and second tubes to be assembled and creating a contact pressure at the level of the area of said contact surfaces (1-1, 2-1) to be welded, and - Means capable of moving in rotation (R) said mirror (4) around the axial longitudinal axis (XX ') of said first and second tubes (1, 2) to be welded, characterized in that it further comprises: - Means for moving in relative translation (T) said mirror (4) with respect to said mechanical system (20a), preferably said relative translation means being able to cooperate with said means able to move in rotation (R) said mirror (4) around the longitudinal axis (XX ') to produce a spiral or helical shaped weld area or a plurality of parallel side-by-side circular welds and / or - means for tilting (B) the surface (4a) of said mirror (4) relative to the axis (XX ') of said first and second coaxial tubes to be assembled in which said mechanical system (20a) is inserted, said means for tilting (B) the surface (4a) of said mirror (4) being able to cooperate with said means able to move in rotation (R) said mirror (4) around the axial longitudinal axis (XX ') to making a spiral or helical shaped weld area or a plurality of parallel side-by-side circular welds. 19. Device (20) according to claim 18, characterized in that it comprises a mandrel (20a) supporting a laser head (3b) or a laser device (3d) and an inclined mirror (4) (B), said mandrel (20a) being suitable for being disposed inside one of said first and second tubes (1, 2) with the same longitudinal axis (XX ') as said tubes, said laser head and said inclined mirror being arranged axially inside said first and second tubes, and said mandrel supporting at least one transparent peripheral wall (21a) expandable radially by inflation, thus forming a first inflatable chamber (21) able to apply pressure against said contact surfaces (1) -1, 2-1) of the two first and second tubes to be welded, said mirror (4) being placed inside said inflatable chamber (21), said mandrel (20a) also supporting an umbilical (3c, 20d), comprising at least one compressed air supply duct for inflating said first inflatable chamber (21) and an electrical supply duct for a motor (20b) capable of moving said mirror in rotation (R) as well as in said relative translation (T) or in said inclination (6). 20. Device according to claim 19, characterized in that said mandrel (20a) supports a motor (20b) capable of driving the rotation (R) of said mirror (4) over 360 ° around the longitudinal axis (XX ') of the mandrel, using a ball bearing (19c) and gear (19a, 19b) system. 21. Device according to one of claims 19 or 20, characterized in that said mirror (4) is adapted to be moved in translation or relative inclination with respect to the longitudinal axis of said mandrel by a worm mechanism (18 ) slaved to said rotation (R) of said mirror around the longitudinal axis (XX ') of said mandrel (20a), or by a trigger pin for said translation or angular displacement step by step. 22. Device according to one of claims 19 to 21, characterized in that said mandrel (20a) further supports a weld control device (3r) comprising a sensor (3r) capable of analyzing, preferably by measuring absorption, a control laser beam reflected on the weld zone, said mandrel being connected to an umbilical (20d), comprising optical fibers, electricity supply conduits. 23. Device according to one of claims 19 to 22, characterized in that said mandrel (20a) further supports a second inflatable chamber (22) comprising a peripheral wall expandable radially by inflation, spaced from said first inflatable chamber (21). in the longitudinal direction (XX ') of said mandrel and, said mandrel being connected to an umbilical (20d), comprising optical fibers and power supply lines. 24. A method of making a pipe using a device according to claim 23 for the establishment of a said sleeve, in which the assembly of unit pipe elements (10-1) is carried out. , 10-2) comprising a said liner (2), and a said connecting tubular sleeve (1) inserted and fixed at only one end of each said pipe element and projecting therefrom, the protrusion of said sleeve defining an end male of each said pipe element able to be assembled with an end devoid of said sleeve defining a female end of another said pipe element, and a weld zone and sealed contact is created by laser heating by fusion between them of the materials constituting a said end part of the sleeve and respectively end part of said liner in contact with one another (1-1, 2-1), and traversed by said laser beam, carrying out the following steps in which : a) introducing a said device (20) for placing a sleeve inside a said unitary pipe element so that said first inflatable chamber is disposed at an end part of said sleeve, and fixing said sleeve positioning device inside said sleeve by inflating a said second inflatable chamber against the internal wall of said sleeve, and b) before or after step a), the sleeve part forming said male end of a pipe element is introduced and forcibly inserted into the female end of the other pipe element, in the longitudinal direction XX ' axially, until said end portion of the sleeve of said male end of said terminal pipe member contacts said terminal portion of the liner of said female end of said pipe member to be assembled, and c) the external peripheral welding of the ends of the two pipe elements is carried out end to end by metal welding (11), and d) inflating a said first inflatable chamber at the level of said end part of the sleeve which is opposite it, and sending a said laser beam, preferably by simultaneously exerting pressure on said end part of the sleeve against said liner end portion in contact with one another to produce a said fusion weld zone at a portion of the contact surfaces of each said end portion of the sleeve and each said end portion of the sleeve in contact one with the other and traversed by the laser beam, to produce a so-called weld zone 5 and sealed contact by fusion, and e) the quality of the weld is controlled by analysis, preferably by absorption measurement, of a control laser beam reflected on the weld zone, and f) said first and second inflatable chambers 10 are deflated and said sleeve placing device is moved in translation.