OA12088A - Insulating tubular complex for driving. - Google Patents

Abstract

The invention concerns an insulating tubular complex (1) characterised in that it comprises: a flexible sheath (4) and an insulating material (5) confined under vacuum between the inner wall (6) and the outer wall (7) of said sheath (4), each of said walls (6, 7) consisting of a multilayer film (10) comprising at least a barrier layer (11), preferably a metallic film and at least a plastic layer (12), preferably thermoplastic, the opposite ends in the longitudinal direction XX' of said tubular complexes being formed by said inner and outer walls sealed against each other, preferably by bonding or heat welding, said insulating material being in the form of a tube or assembled tube arcs. The invention also concerns an insulated pipe and an assembly of two coaxial pipes comprising an inner pipe (3) and an outer pipe (2), preferably underwater pipes designed for great depths, and a method for making same.

Description

12088 1

The present invention relates to an insulation system for any type of conduct including submarine pipes carrying hot or cold fluids. The present invention more particularly relates to an insulating tubular complex capable of being placed in the space between two coaxial pipes comprising an inner pipe and an outer pipe, preferably submarine pipesdestinées at great depths.

It applies in particular to submarine pipelines installed on the oilfields at very great depths, as well as to the lines suspended between the seabed and a surfaced vessel on the said oil field.

It also applies in the fields of aeronautics and space industry where the concept of weight is of prime importance.

In most industrial areas, high-performance insulation systems are required to maintain the fluids conveyed in the pipework at constant temperature, so that transfers between equipment can be made possible over long distances, reaching for example several hundred meters or even several kilometers. . Such distances are common in industries such as oil refineries, liquefied natural gas facilities (-165 ° C), submarine oil fields which extend over several tens of kilometers. Such oil fields are developed by increasing water depths which can reach and exceed 3000m.

Many systems have been developed to achieve a high level of thermal performance and specific versions have been developed to respond more appropriately to deep seabed, ie to withstand the pressure of the seabed. the water being 1 bar for 10m deep, the pressure to which the pipe must resist is then 100 bars for 1000m of depth and 300 bars for 3000m.

The most efficient technologies that have been developed to achieve this goal are the so-called "Pipe In Pipe" or "PIP" technologies, ie "driving in a pipe", in which an internal pipe conveys the fluid and a coaxial outer pipe to the previous one. in contact with the environment, it is water. The annular space between the two pipes can be filled with an insulating material or be emptied of any gas.

In the case of using a polyurethane foam insulating material, the necessary thicknesses are generally important, for example 5 or 10 cm, which requires the use of a large diameter outer pipe. However, this pipe must withstand the pressure of the bottom without imploding which implies an extra thickness of steel to withstand the pressure and extra steel surface due to increased diameter. In addition, the annular space filled foam creates additional buoyancy that is often forced to compensate by increasing the weight of the pipe, which is often obtained by increasing the thickness of the outer pipe. Thus, in many cases, the design of the external pipe is governed by considerations of non-buoyancy of the PIP assembly, more than by the need to resist the bottom pressure.

To overcome this drawback, much more advanced technologies have been developed in which it is sought to minimize the annular space between pipes, in particular with the creation of a vacuum in the interstitial zone. In fact, the vacuum thus created is then an excellent insulator, and an annular space of 5 to 10 mm is insufficient. The PIP is comparable in terms of performance to glass "thermos" bottles known to everyone. In order to improve the insulation, the radiation is furthermore limited by wrapping the outer part of the inner pipe with a reflective film, generally made of an aluminum film optionally combined with thermoplastic materials.

The pipes are then prefabricated in unit lengths of 6 to 12 m and then, when laying together to each other to form a continuous connection. In case of damage to one or more lengths of PIP, thermal bridges are created which, if they remain punctual and limited in number, have no significant impact on the behavior of the pipe, which continues in general to ensure its function in time.

The pipes thus produced in the PIP technology based on a strong push however have the following disadvantage. Fluid, which is a subsea well, is a mixture of crude oil, water, gas and various aggressive compounds such as CO2 and H2S. The internal pipe, generally made of carbon steel, is subject to corrosion phenomena due to the fluid and which have the consequence of producing hydrogen atom H +, the latter having a tendency to migrate in atomic form through the matrix of iron and carbon steel, to come recombine, on the outer wall of the inner pipe, so in the annular space between the two coaxial pipes, pourform hydrogen gas of formula H2. The vacuum created in this annular space then degrades due to the increase in hydrogen pressure, which is an excellent conductor of heat, which goes against the intended purpose.

Various means have been developed for overcoming this disadvantage. One known method consists in introducing into the annular space of a compound known as a "getter", the function of which is to absorb this hydrogen gas to maintain the partial pressure of lower hydrogen and thus maintain the desirable vacuum level throughout the life of the field, which may exceed 20 years. The "getter" is introduced during the manufacture of the PIP and before the final sealing after the vacuum, 1 2088

It has also been envisaged to use corrosion-resistant steels, such as stainless steel or duplex, for the inner pipe at least, but the pipes then become extremely expensive and generally do not constitute an economically acceptable solution.

It is also common to coat the inside of the conduit with a protective film, for example epoxy type, whose function is to avoid contact between corrosive agents and carbon steel. However, because of pipe splices made on site, the welding process destroys this protection locally and creates areas prone to corrosion. In addition, in case of damage to this coating bypassing cleaning tools or by abrasion due to the sandvehiculated at the same time as the effluents, the surface may sedégrader in time and the phenomenon of hydrogénomatic migration of s to amplify with time.

Furthermore, the technology developed in the field of household electrical appliances is known, based on the production of panels consisting of a microporous material confined in a casing made of a film, generally heat-sealed at its ends, in which it is previously created. at final sealing, a vacuum-driven, that is to say of the order of 1 millibar or less. The film is a multilayer complex comprising a barrier consisting, in general, of a continuous aluminum film associated by bonding or adhering to thermoplastic films, the latter making it possible to seal the assembly. Such films are commonly used in the food and beverage field to preserve under neutral or vacuum atmosphere products such as milk, fruit juice and coffee.

It has been proposed in International Application WO96 / 32605 to produce panels having a three-dimensional surface by ply of flat panels of polyurethane foam, in which grooves are made. However, the realization of tubular panels is not described. In any event, this mode of surface formation 1 2088 curve by folding flat panels along grooves does not demimize the space occupied by the panel. The goal of efficient insulation is to limit heat transfers by conduction, convection and radiation and to create reflective screens whose function will be to return energy radiation. The limitation of the conduction can be obtained by depletion of the molecules in the presence, responsible for said heat transfer, or by trapping molecules within organized destructures whose cavity diameter is of the same order as the wavelength of the radiation to be confined. Thus, the radiation franking this kind of structure are trapped locally, because instead of crossing the medium directly, their path is reflected cell in cell and the average transfer speed is divided by 10 or more. Such materials are known as nano-materials because their basic structure creates cells, certescommunicantes, but whose cavity size is of the order of nano-meter. Such products, referred to in an aerogels variant, are produced by the company Monsanto (USA).

Thus, the problem is to provide a high performance insulation system that can be used in a wide variety of applications and to respond in particular to the conditions encountered in offshore oil field developments.

In addition, the thermal insulation requirements of the present invention are: a very high performance insulation corresponding to values of heat transfer coefficient of the order of a few milliwatts,. a small footprint insulation to be able to selocate in small confined spaces (this is the case in aerospace, aeronautics, oil at sea or on land), 1 2088. a light thermal insulation so as not to disturb and / or increase the primary structure to be insulated (the insulation must not induce stresses and strains out of norms),. a thermal insulation that is easy to use and adaptable to all forms of piping,. thermal insulation covering a wide range of temperatures from low temperatures (-100 ° C or lower) to high temperatures (of the order of 150 ° C),. thermal insulation with a service life of around 20 years that can be certified or meets administrative regulations.

To do this, the present invention provides a tubular-insulating complex capable of being placed around a pipe, and more particularly in the space between two coaxial pipes comprising an inner pipe and an outer pipe, preferably underwater pipes intended for the great depths. characterized in that it comprises: a flexible envelope and an insulating material confined between the inner wall and the outer wall of said envelope, each of said walls consisting of a multilayer film comprising at least one screen layer including a screenplay the role of molecular barrier, preferably a metal film and at least one preferably thermoplastic insulating layer, said insulating material being in the form of a tube, and the opposite ends in the longitudinal direction XX 'of said tubular complexes being each constituted by the respective edges of said inner and outer walls e said tubular complex, sealed against each other, preferably by gluing or heat sealing.

The inner wall corresponds to the wall of the envelope placed against the pipe, in particular the inner pipe in the case where the tubular complex is placed in the space between two coaxial pipes. Likewise, the outer wall corresponds to the wall of the casing placed on the other side of said insulating material on its free outer face or against the inner surface of the outer pipe when the tubular complex is placed in the space between two coaxial pipes. .

Said opposite ends of the tubular complex and said respective edges of the inner and outer walls in the longitudinal direction XX 'of said complex have a cylindrical and cylindrical shape whose axis corresponds to said longitudinal direction.

More particularly, said opposite ends in the longitudinal direction XX 'of said tubular complex are each formed by the respective edges of the internal faces of the envelope of each of said walls sealed against each other.

The characteristic that the insulating material is present in the form of a tube means that the insulating material is constituted by a solid material which is shaped in itself once applied and more specifically in a tubular form.

Said tube of insulating material may be made in one piece or it may comprise several arc of assembled tubes, including twohalf-assembled tubes. But, said tube or said assembled tube archesis or are enveloped (s) by a single outer wall and a single continuous inner wall. As a result, said outer and inner walls do not present a discontinuity that can generate insulation breaks around the pipe.

Preferably, the pressure inside the envelope is less than 5 millibars, more preferably less than 1 millibar.

Advantageously, each wall of said envelope forms a surface of revolution with respect to a longitudinal axis XX ', each wall being obtained by sealing one against the other, preferably by bonding or heat sealing, of the two opposite longitudinal edges of a composite rectangular filmmulticouche the same wall, the splicing done along a generatrix of the said surface of revolution. 1 2 088

In one embodiment, said two opposite longitudinal edges of the wall are sealed against each other on the same face towards the outside of the envelope.

It is therefore the internal faces of the envelope, that is turned towards the inside of the envelope, which are sealed against each other. This method of realization is more particularly appropriate when the filmmulticouche constituent of the walls does not have the same composition on each of its faces, with in particular only the inner face of the envelope covered with a sealable binder.

Preferably, said opposite longitudinal edges of a same wall, more preferably the outer wall sealed one against the other towards the outside of the envelope are covered by an additional filmmulticouche layer so as to cover the edge of said edgesraboutés l against each other of the said walls.

In another embodiment the two longitudinal edges of the wall, preferably the inner wall are sealed against each other, inner face to the casing of one against the outer face of the envelope of the other.

In a first embodiment, said respective edges of the inner faces of the shell of the inner and outer walls to said opposite ends sealed to one another, comprise at least one in said edges of the outer wall, preferably a plurality deplis, more preferably still and symmetrically spaced along the circumference of said ends. Thus, insofar as a portion of the edges of the outer wall are folded and sealed on themselves, the excess length of said edges of the outer wall relative to those of the inner wall does not generate any risk of loss of sealing del ' envelope.

In this first embodiment, said opposite ends and said respective edges of the inner and outer walls sealed to each other form a cylinder of substantially the same diameter inner diameter of said tube of insulating material. 1 2 088

In a second embodiment, said respective edges of the inner faces of the shell of the inner and outer walls, sealed one against the other at said opposite ends of said complex, do not present a fold, and the inner wall comprises folds in its central zonecentral in contact with said pipe between said opposite ends.

In this second embodiment, said respective edges of the inner and outer walls at said opposite ends form a cylinder of diameter greater than that of the inner pipe, but substantially identical to the outer diameter of said tube of insulating material.

To achieve the required performance according to the present invention, a thermal insulation is required which stops the convection. Ilexiste several types of insulating materials capable of achieving this phenomenon.

In one embodiment, the insulating material inside said envelope is a nano-material, in particular an airgel of silica or titanium oxide. In another embodiment, the insulating material is a foam of microporous synthetic material. One of them is polyurethane foam with open cells. Thermal radiation whose wavelength is of the order of a few nanometers is trapped in the open cells themselves, with a diameter of the order of a few nanometers. .

To improve the performance of these basic materials, it is important to empty the gas it contains, usually air, to limit contact heat exchange to a minimum. In the case of polyurethane foam, when the vacuum quality in the open cells of the foam reaches a value of less than 1 millibars, the heat transfer coefficient drops by about 6 milliwatts / m / ° C, which is the highest value so far. low achieved for any type of material. 10 1 2088

The vacuum is maintained at this level of value over 20 years thanks to a welded thermoplastic film that prevents or limits the intrusion of gas (H2, CO2, etc ...) at least through a metal film (general aluminum). This film is structured to withstand temperature variations as well as film-to-film welding.

This type of product is now used in the consumer refrigeration industry (refrigerators and similar appliances).

The principle is adaptable to other materials with an interesting insulation capacity which can be more or less economical compared to open-cell polyurethane foam. Other open-cell organic materials are described in WO 96/32605, especially polymers. of polystyrene, polyethylene, polyacrylic, polyvinyl chloride.

The flexible multilayer films constituting the envelope include layers of plastic materials such as polyester, polyvinyl chloride, polypropylene, polyvinyl alcohol.

Preferably, the metal layer is made by sousvide deposition on said plastic film. Alternatively, the plastic film can be laminated to a metal sheet.

Preferably, the plastic layer is made of or coated with a layer of heat-sealable thermoplastic material, in particular by heat-sealing, it consists in particular of polymers which have a melting point of less than 200.degree. C., such as polyolefin resins, in particular polyethylene or PVC resins. , polyacrylonitrile, polyamide.

More preferably, the metal layer is coated on each side with a plastic layer, preferably thermoplastic.

Flexible multilayer films that can constitute the envelope are also described in WO 96/32605.

Said vacuum insulating tubular complexes thus produced are threaded against each other to constitute an assembly having a minimum of thermal bridges, said thermal bridges being located at the connection of two insulating tubular complexes. For this, the insulating tubular complexes according to the invention are of the longest possible length, for example 6 m, the length being generallyallimitated by the handling problems and the risk of damage during the assembly of the pipe PIP.

In an advantageous embodiment, the tubular complex according to the invention comprises an additional screen between said insulating material (5) and said outer wall (7) of the envelope, and / or outside said envelope, said additional screen being constituted by a reflective high performance film preferably in silver mylar.

The present invention also relates to an insulated pipe or a set of two coaxial pipes comprising an internal pipe and an external pipe (PIP), preferably submarine pipes intended for great depths comprising unitary unit complexes according to the invention placed around said pipe. conductor or in the space between said two coaxial ducts and preferably around said external duct and connected to each other said ends directly or via connecting elements.

In one embodiment, said unitary tubular complexes are threaded against each other at their said ends which are fitted, in particular elastically, into each other overlapping.

Preferably, first unitary unit complexes having ends forming a cylinder of diameter substantially identical to that of the outer diameter of said tube of insulating material are placed alternately, and second tubular complexes having ends forming a cylinder of diameter substantially identical to that of the internal diameter of said tube. of insulating material. Thus, an end of a first large diameter unitary complex cooperates with an end of a second unitary complex of smaller diameter. 12 1 2 08 8

In another embodiment, said unitary tubular complexes have complementary surfaces at their ends which cooperate so that said ends of two unitary tubular complexes fit into each other.

More particularly, said complementary surfaces are not each formed of a single flat surface orthogonal to the axelongitudinal (XX ') of said tubular complexes, but comprise three-dimensional surfaces consisting of several planar orthogonal surfaces to said longitudinal axis in staircase interconnected by desurfaces of coaxial revolution not orthogonal to said axis.

When said vacuum insulating tubular complex is positioned around the inner pipe of a set of two coaxial pipes, it is protected by the outer pipe, the latter being dimensioned to maintain the ambient pressure in its place of installation. The pressure in the space The ring between the inner pipe and the outer pipe may be arbitrary, preferably small, ie atmospheric pressure. More particularly, saidpressure must not exceed a value corresponding to the implosion of the vacuum insulating material tube by exceeding the compression admissible by the insulating material confined in said multilayer film constituting the envelope in which a high vacuum prevails. In the context of the invention represents the implosion value is at most a few bars, for example 3 or 4 bars, and the pressure in the space between said two outer and inner ducts outside the casing is less than 3 bar, preferably identical to atmospheric pressure.

Preferably, said outer and inner conduits are interconnected by central mechanical links preferably comprisingparts of plastic material, preferably still elastomer, parts against which abut the said ends of some of said tubular complexes.

Another limitation is caused by the differential behavior of the inner pipe with respect to the outer pipe. In effect, when the inner pipe is under pressure, it tends to become longer due to the bottom effect. In the same way, the temperature variation of said inner pipe increases the length. But the external conductor remaining at the pressure of the seabed and the ambient temperature, generally around 4 ° C, it results in differential forces between the two pipes, which implies the installation of said mechanical links spaced regularly ounon and located all along the PIP. The space between two said mechanical links is calculated so as to prevent the decompression stress generated within the wall of the internal pipe, due to the clipping of the external pipe preventing it from lengthening, from leading to mechanical instability of the wall. of the internal pipe called "buckling". Depending on the case, this space can be 6 m in unfavorable cases or reach 15 to 20 m in the case of inner pipes of diameter, for example 14 "to 20". The background effect and buckling being known to those skilled in the field of oil piping, will not be developed in detail.

Thus, the interval between two successive mechanical links will be filled by one or more vacuum insulating tubes fitted on said mechanical links and at the junction of each tube between them, so as to limit the thermal bridges to the right successive junctions.

Advantageously, said mechanical link will consist of a material that is not very conducive to heat and that achieves a good compromise between mechanical performance and insulation performance. For example, such a mechanical link can be made by a molded part of elastomeric or thermoplastic type or from reticulated resins, charged or not.

The present invention also relates to a manufacturing method of an insulated pipe or a set of two pipescomprenant the steps in which: 1 1 is applied, in particular is deposited directly said insulation material on a first multilayer film constitutive of said inner wallcovered on said duct and in particular where appropriate around said inner pipe, so that said insulating material has a tubular shape, and then said insulating material is covered with a second molten film constituting said outer wall of the envelope. 3 / said opposite ends of said complex are made to ensell said respective edges of said outer and inner walls in said longitudinal direction.

The final sealing of the inner and outer walls occurs after evacuation at the desired absolute pressure level, which should be as low as possible, for example of the order of one millibar.

In one embodiment in step 3 / above, at least one ply is made in said edges at said ends in the longitudinal direction of the outer wall, preferably a plurality of pleats regularly and symmetrically spaced along the circumference of said ends of said complex tubular.

In another embodiment, in step 1 / pre-folds are made in said inner wall between said edges at said ends of said inner wall. The joining surfaces of the two semi-tubes are not plane surfaces diametrical with respect to the dittube, but preferably constitute three-dimensional surfaces.

The insulating tube thus obtained is autonomous and has the advantage of not having a longitudinal cut. The system limits the interference between the two walls to radial losses through vacuum layer which are directly related to the value of the thermal transfer coefficient.

The radial cuts are spaced according to the largest length manufactured (several meters, 12 at most);

In another embodiment of the manufacturing method according to the invention the tube of insulating material is made by splicing against one another around said pipe, preformed half-tubes. Advantageously, the joining surfaces. the two half-tubes are not flat surfaces diametrical with respect to said tube, but preferably constitute three-dimensional surfaces, so as to obtain a path as elongated as possible and reduce the pertesthermiques.

The insulating system obtained is a complete tube which can notably slip on the pipe to isolate at the time of its implementation.

The insulation system according to the present invention has the following advantages: the system is very light and allows manipulation by only one person; the system is sufficiently flexible to accept the manufacturing tolerances of the pipes without particular precautions and thus enables its use on mobile or dynamic pipes whose curvature can vary within the capacity of the pipework itself; - the system can adapt to all forms that are encountered on rigid pipes such as elbows, tees etc ... The formessont then realized thanks to the principle of overdouage (industry consigneonners); - Although the system only supports a small depression variation, it can be used in installations subject to external pressures through the use of a stiff or semi-rigid outer casing that will accept external pressure; - speed of manufacture and use. Other features and advantages of the present invention will become apparent in light of the following detailed description, with reference to the following figures in which: FIG. 1 is an axial side view of a PIPcomprising a vacuum insulating tubular complex located between inner pipe and outer pipe, 16-mk; FIG. 2 is a longitudinal section along a generator of a vacuum insulating tubular complex according to the invention detailing a mode of welding the opposite circular ends, FIGS. 3 and 4 are radial sections. FIG. of the envelope of a vacuum insulating tubular complex, according to the invention, • Figures 5 and 6 are longitudinal sections of multilayer composite films (10) comprising an aluminum film 11 sandwiched between thermoplastic layers (12), • The figure 7 is a side view section of a splice of two opposite longitudinal edges of the inner wall film according to FIG. 4, FIGS. 8 and 9 are side view sections of a splice of two opposite longitudinal edges. of the outer wall film according to FIG. 4 respectively before and after the heat effect, • FIGS. 10 and 11 are sections in side view according to FIG. 9, which furthermore comprises a multi-screen furthermore, respectively before and after effermeter welding, • Figs. 12, 13 and 14 are axial sections for an inner pipe on which the insulation element is directly manufactured, the assembly being shown at three stages of said Manufacture • Figures 15, 16 and 17 are sections of the tubular insulating element reconstituted from two half-tubes. FIGS. 18A and 18B are longitudinal sections of a set of two PIP coaxial pipes detailing the connection of two directly connected insulating complexes. • Figure 19 is a longitudinal section of a PIP detailing the connection of two insulating complexes through two half shells of insulating complex. 20A and 20B are respectively cutaway and perspective views of insulating complexes in the form of half-cups according to FIGS. 15 and 19. FIGS. 21 and 22 detail a preferred embodiment of the various welds of the longitudinal edges of the internal walls (Figures 21A and 21B) and outer walls (Figures22A and 22B) longitudinal and circular. FIGS. 23a to 23d detail an embodiment of the wettings of the respective edges of the outer walls and internecelled one against the other with folds in the edge of the paroiexterne. FIG. 24 is a side view detailing the final phase of outer longitudinal laser coating of FIGS. 22A and 22B. • Figure 25 is a side view of the pipe associated with a cut of the insulating complex in a variant of assembly and circular welding of the respective circular edges of the outer and inner walls with folds in said inner wall. FIG. 26 is a sectional side view of the assembly of two different types of tubular insulative complex embodiments, nested within each other.

FIG. 1 is an axial side view of a PIP comprising an internal pipe 3 held coaxial with an external pipe 2 by means of regular or evenly spaced mechanical links 9, a vacuum-insulating tubular complex being situated between the two ducts; .

The tubular complex 1 comprises: - an envelope 4 and an insulating material 5 confined between the inner wall and the outer wall 7 of said envelope 4, - each of said walls 6, 7 being constituted by a multilayer film 10 comprising at least one layer screen 11 playing the molecular barrier barrier against the migration of gas, preferably a metal film and at least one plastic layer 12, B The opposite circular ends 8a, 8b of said complexubstances being constituted by the respective edges 65, 7sdesdits inner walls 6 and 7 external connected directly against each other by heat sealing, said insulating material being in the form of continuous rigid tube, without discontinuitésur its periphery. B The tubular insulating material 5 is made of open-cell polyurethane foam,

In Figure 1, said unitary tubular complexes 1 are threaded into each other at their ends 8a, 8b which are thus adjusted elastically into each other in sechevauchant; said external and internal conduits 2 3 are interconnected by mechanical links 9 comprising parts elastomeric material, parts against which abut the said ends 8a, 8b of some of said tubular complexes 1.

In FIG. 2, said opposite ends 8a, 8b in said longitudinal direction XX 'of said tubular complex are each constituted by the respective edges 65, 7s of the internal faces of the envelope of each of said walls, sealed against each other.

In FIGS. 2 to 4, each wall 6, 7 of said envelope 4 forms a surface of revolution with respect to a longitudinal axis XX ', each wall being obtained by splicing one against the other, by bonding or heat sealing, the edges opposed longitudinal 61/62 7i / 72 of rectangular multilayer film comprising said wall, the splicing along a generator of said surface of revolution.

In FIGS. 3 and 8 to 11, said two longitudinal edges 61 / 627i / 72 of the inner 6 and outer 7 walls are spliced outwardly from the envelope one against the other on the same face, c ' is direc- tionally inward and outward of the tube. 19 1 2088

In FIGS. 4 and 7, the two longitudinal edges of the internal wall 6 are joined against the other inner face of the envelope of one 63 against the outer face of the envelope of the other 64.

In Figures 10 and 11, said longitudinal edges of the wallsraboutés outwardly of the casing are covered by an additional filmmulticouche 13 so as to cover the edge of the diitbords raboutés against each other, which increases the sealing of the envelope by increasing the path for the gas molecules.

In FIGS. 9 to 11, there is shown the hot-melt thermoplastic layer 14 which makes it possible to obtain the heat-sealing bonding of the outer plastic layers constituting the multilayer films 10 of the flexible envelope.

In FIGS. 12 to 14, there is shown a method of manufacturing the isolating complexes 5 according to the invention.

FIG. 12 shows a first step of applying a multilayer film 10 to the inner pipe 3 so as to subsequently constitute the inner wall 6 of said shell 4.

Thus, the pipe is wrapped directly with a composite film longitudinally welded preferably according to the principle described in Figure 4

FIG. 13 shows a second step which consists in applying the insulating material 5 made of polyurethane foam, which is deposited directly in a tubular form on the said multilayer film constituting the inner wall 6.

The insulating material 5 is deposited on the film 10, for example by spraying in synchronization with the rotation of the inner pipe, so as to obtain a thickness greater than the thickness sought. After hardening of the insulating material, if the outer face isirregular or excessive diameter, said face is machined parturning or milling to achieve the desired tubular shape. 20 1 2088

Then the last step in FIG. 14 consists in applying to said insulating material 5 having a tubular shape a second thick film 10 constituting the outer wall 7 of said envelope 4.

To do this, the film of the outer wall is then wound around the insulating material 5 and then welded longitudinally as described in FIG. 4, or prefabricated to form an inner circumferential tube slightly greater than the outer circumference of the insulating material tube, then slid around said together inner pipe -insulating material, to constitute the outer wall.

After evacuation, the edges 65, 7 of the outer and inner walls are sealed at their ends 8a, 8b to form the envelope 4.

By doing so, the clearance between the inner pipe 3 and the insulating complex is minimum or zero and the insulating complex, constructed in one piece has no material discontinuity in the thickness of the insulating wall, which limits the thermal bridges describedci -after.

FIGS. 15 to 17 show another embodiment of a tube of insulating material 5. This is made from two half-tubes 15a, 15b which are preformed before being applied to the inner pipe 3.

FIG. 15 represents an insulating system prefabricated in two half-shells 15a, 15b assembled in a diametrical plane. The surfacejunction 15 between the two half-shells 15a, 15b then has a minimum length between the outside and the inside of the insulating tube.

FIGS. 16 and 17 show junction surfaces which represent extended paths: the junction surfaces of the two half-tubes 15a, 15b are not planar diametrical surfaces comprising the longitudinal axis XX 'of said tube, but are three dimensions obtained from flatplane surfaces (Figure 16) or curved surfaces (Figure 17). 21 1 2088

The joining surface 15 is an area where the thermal conductivity is increased. Therefore, it is preferable that the path between the inner surface 16 and the outer surface 17 of the pipe is as long as possible as shown in Figures 16 and 17.

These junction planes 15 having an extended path, do not remove thermal bridges, but minimize their consequence by lengthening the path, thus increasing the performance of the complex insulation.

FIG. 18A shows the connection of two tubular insulating complexes having, at their ends, complementary stepped surfaces 16 in order to increase the path of heat better represented in FIG. 18B. The complementary surfaces 16 comprise two octagonal planar surfaces 16i, I63 to the longitudinal axis XX 'of said ducts, said planesoctogonal surfaces being connected by a tubular surface of revolution I62 so that the complementary surfaces can fit into one another, the sealed ends of the outer and inner walls of said ditscomplexes unitary tubulars protruding respectively on the side of the external duct and the side of the inner pipe.

FIG. 19 shows a method of manufacturing a set of two pipes in which: 1. Two soldunit subsystems of coaxial pipes 17a and 17b are assembled by welding 18, comprising tubular isolating complexes 1a and 1b which do not open the ends 19a and 19b of said inner ducts, 2. The thermal insulation is completed between the two ends of the tubular complexes la and lb with the aid of connection elements consisting of two half-tubular complexes 20a and 20b. Each of the two half-tubular complexes 20a and 20b comprises a semitube of preformed insulating material confined under vacuum in a said envelope composed of said multilayer films. The two half-tubular complexes are coupled together around said internal conduits 3 at the level of their uncovered ends 19a and 19br

In FIG. 19, the tubular insulating complexes 1a, 1b are spaced from a length of up to 200 mm, preferably 400 mm, so as to facilitate access to the zone making it possible to assemble the internal pipes 3, by example soldering.

FIGS. 21a and 21b show respectively, in side view and in section, the inner pipe 3 on which the inner wall 6 is installed, the opposite longitudinal edges 63, 64 of which have been welded to one another, in accordance with FIG. mode shown in Figure 4, and folded to be inserted around the pipe.

The tubular elements of insulating material 5 are then installed around the pipe 3 as shown in Figure 22a, and the paroiexterne 7 of the casing is put in place, then its opposite edges 7i, 72 are welded longitudinally as shown in Figure 22baccordant with provisions of Figure 4.

The realization of the circular welding of the respective edges 65, 7ydes inner and outer walls to said opposite ends 8a, 8b of said complexes, presents a difficulty because the two cylinders formed by the inner wall and the outer wall do not have the same diameter and therefore do not same circumference. An embodiment of lasoudure according to the invention is detailed in FIGS. 23a to 23d, in which spot welding 24 of the outer wall 7 is carried out on the inner wall 6 in the six successive positions a, b, c, d, e and f as shown in FIG. 23b, which leads to the configuration of FIG. 23c. In this configuration, the outer wall 7 of the envelope always has the same circumference, but the surplus lengths 23 are substantially uniformly distributed over the circumference of the inner wall 6. FIG. 23d details the final phase of the welding consisting of 23 "W-1 2088 moving the welding element, here represented by a heating drum 22roulant, simply by leaning on the outer wall.The drum 22pushes before it the excess length 23 until the next score is reached .In this position, the drum The two outer faces of the outer shell are then brought closer to one another and the welds continue to be welded together, thus successively recovering the six initial superlongers 23 separated by the six spot welds. obtained has the feature of being made, in the circular part, between the paroiexterne and the inner wall of the envelope and in the zone of resorption of excess lengths between the outer wall and itself. Said respective edges 65, 7s of said inner and outer walls sealed to one another comprise, in said edges 7s of the outer wall, a plurality of pleats 21 regularly and symmetrically spaced along the circumference of said ends 8a, 8b.

FIG. 24 describes a preferred embodiment of the longitudinal weld of the outer wall facilitating the emptying of the insulating and insulating complex. The sequence welding is then: • establishment of the inner wall 6 on the pipe 3 after longitudinal welding as detailed in Figures 21a-21b. Placing the insulating material 5 and the outer wall 7 of the envelope as detailed in FIGS. 22a, 22b and longitudinal welding of the opposite longitudinal edges 7 1, 7 2 of the outer wall of the envelope according to the "pilgrim step" modedit . This method of welding consists insouder in the longitudinal direction XX 'a length of envelope 31, for example 75cm, then to leave a non-welded length 32, for example 20cm, then new a welded length and so on. The external generatrix of the outer wall 2088 24 of the envelope is then observed to be a succession of welded zones 31 and open zones 32. The circular end welds 8a, 8b are then produced according to the mode previously described in FIGS. 23d. The insulating tubular complex is thus completely welded except at the location of the open zones 32 shown in FIG. 24. The assembly is then installed in the vacuum chamber and a device consisting of a press 35 equipped with actuators 33, for example pneumatic, to the end of which are installed heating rules 34, is disposed at each of the buttonholes. The actuators 33 are shown in the retracted position and the edges of the open zone 32 are kept apart, for example by means of double-sided adhesive tape which ensures the bonding of the edges on the heating rulers 34, preferably in a slightly offset zone compared to the active zone of heating. The open zone on the right will be equipped with its pressing system before the vacuum chamber is closed and the vacuum is achieved. When a sufficient vacuum is reached, the getter, in the form of pellets or granules, is preferably distributed in each of the open areas 32, then the press 35 is closed thanks to the actuators 33 and the heating rulers 34 put in temperature to effect the final sealing . By doing so, it sets up legetter without the latter has been in contact with the ambient air, which would have resulted in consuming unnecessarily part of adsorption sacapacity. To do this, the getter is stored in a vacuum tank or under inert gas, the latter not being in communication with the vacuum chamber once the level of videdeiréiré reached.

These open zones 32 constitute a kind of "buttonholes" and have the considerable advantage of being able to optimize the vacuum drawing time, since each of the open zones 32 drains a disjected portion situated to its right and to its left relatively small, by 1 2 08 Example 50cm on each side, whereas in the case of an insulation complex without "buttonholes" drawn to vacuum from its ends 8a, 8b, the gas molecules will have to travel a distance of at least 3m in the case of a tubular complex insulation 6m. The position and length of the lockers 32 will depend on the type of insulating material and the amount ofgetter that is to be distributed along the length of said tubularisolating complex. For example, an insulating tubular complex of 4m delongeur comprises a first buttonhole 32 20cm long located 40cm from the end, then three identical buttonholes 32 20cmespacées 80cm, the latter being then 40cm from the second end.

FIG. 25 describes a variant of the mode of assembly of the internal and external walls of the insulating tubular complex in which the circumference of the inner wall is substantially identical, in fact slightly slightly smaller than that of the wall external to said opposite ends 8a, 8b, this circumference corresponding substantially outside diameter of the tube constituted by the tube of insulating material 5.The edge 65 of the circular end of the inner wall of the complexetubulaire isolant has a diameter much greater than that of the inner pipe 3. Thus installs said inner wall 6 welded surelle- even longitudinally, around the pipe 3 and one slides each end 8a, 8b a mandrel 40 whose diameter corresponds substantially to the diameter of the tube of insulating material 5. The edges 65 at the ends of the inner wall 6 is therefore directly in contact with the mandrels 40, without significant play between the edges 65,7s r of the internal and external walls. The length of the circumference of the central zone of the inner wall 6 is resorbed with respect to that of the pipe 3 by reducing the diameter of the tube formed by the internal wall, by uniformly tightening the entire central part of the internal wall 6 in contact with the pipe 3 between said end edges 65dudit tube, which creates folds 41 in the central area. Said plies 41 are dimmed in the tapered zone 42 of connection to end without folds in the region of the edges 65 in contact with the mandrels. The insulating elements 5 are then put in place and the outer wall 7 is installed and then welded in "no pilgrim" as described above. At the ends 8a, 8b are then carried out with the aid of a device formed for example of a heating drum 43 which simply rolls on the periphery of the outer wall 7 of the envelope and presses the latter in a controlled manner.

The welding device may be of the heating type, ultrasonic or induction, it may be a drum or a pad simply rubbing on the outer wall to be welded. The welding can be replaced by gluing, double-sided adhesive or a combination of these methods.

FIG. 26 describes an advantageous way of isolating a pipe of great length by combining the two types of fabrication described above. For example, on line 3, a first insulating complex IA is installed in the manner described in FIGS. 14, 21-22-23. Then, it is juxtaposed an insulating complexIB made in the manner described in Figure 25, which allows closer approach the two tubular insulating complexes type A and B and reduce the thermal bridges. Alternation A-B-A-B -... will be maintained until a mechanical link 9 as detailed in Figure 1 is required to maintain the spacing between the inner and outer pipe. For the sake of clarity of the drawing, and to understand the encircling of the circular ends 8a, 8b of the tubular-insulating complexes, those of type B have been represented with a larger diameter. But, in fact, the first tubular complexes IA have ends 8a, 8b forming a cylinder. of diameter substantially identical to that of the inner diameter of said tube of the insulating material 5 and the tubular complex sectors IB have ends 8a, 8bforming a cylinder of diameter substantially identical to that of the outer diameter of said tube of insulating material 5.

The insulating tubular complex remaining a fragile product, it is advantageously protected by an outer protective envelope 1 2088 27 (not shown), mechanically resistant. This protective envelope may be a simple wrapping of a resistant thin film, or it may be constituted by the application of a composite material, for example based on epoxy resin or polyurethane, which polymerizes either under the effect of the ambient heat or ultraviolet radiation.In the case of simple driving, this protective jacket playale role of outer shell. In the case of PIP, this protective envelope will advantageously avoid damage to the insulating and insulating complex during the installation of the outer casing by sliding over said tubular insulating complex.

This type of high-performance insulation targets any type of pipe from 2 "(inches) to 30" (inches) in diameter, and especially undersea production runs from 6 "(inches) to 14" (inches). The insulation thickness required to achieve the desired performance levels is in the range of 5 mm to 2 cm thick for an insulating material of open-celled polymeric foam. In some applications where extreme insulation is desired, a thickness up to 5 cm is possible. 20

Claims (23)

28 1 2088 CLAIMS 1. Insulating tubular complex (1) capable of being placed around a secondary stream 3, preferably an underwater pipe intended for large depths, characterized in that it comprises: - a flexible envelope (4) and an insulating material (5) confined between the inner wall (6) and the outer wall (7) of said envelope (4), - each of said walls (6, 7) consisting of a multilayer film (10) comprising at least one screen layer ( 11), preferably a metal film and at least one plastic layer (12), preferably thermoplastic, - said insulating material being in the form of a tube (5, 15a, 15b), and - the opposite ends (8a, 8b) in the longitudinal direction (XX ') of said tubular complexes being each constituted by lesbords respective (65, 7s) of said inner and outer walls of said complexetubulaire, sealed against each other, preferably by bonding outhermosoudage. 2. The tubular insulating complex according to claim 1, characterized in that each wall (6, 7) of said envelope (4) forms a surface of revolution with respect to a longitudinal axis (XX '), each wall being obtained by sealing one against the other, preferably fleeting or heat-sealing, opposite longitudinal edges (61 / 62,7i / 72) of a rectangular multilayer film constituting the same said wall, the splicing being along a generatrix of said surface revolution. 3. tubular insulating complex according to claim 1 or 2characterized in that said two longitudinal edges (61/62, Ίχ / Ίι) of the wall (6, 7) are sealed against each other on the same side towards outside of the envelope. 4. tubular insulating complex according to one of claims 1 to 3 characterized in that said opposite ends (8a, 8b) in said longitudinal direction (XX ') of said tubular complex are formed each by the respective edges (65, 7s ) inner faces of the envelope of each of said walls, sealed against each other. 5. tubular insulating complex according to claim 4, characterized in that said respective edges (65, 7s) of said internal and external walls sealed against each other comprise at least one fold (21) in said edges (7s) of the outer wall, preferably a plurality of pleats regularly and symmetrically spaced along the circumference of said ends (8a, 8b). 6. Tubular complex according to claim 4, characterized in that said respective edges (65, 7s) of said inner and outer walls, sealed against each other, form a cylinder of diameter substantially identical to that of the outer diameter of said tube of insulating material ( 5), and said inner wall of the envelope comprises folds (41) in the zonecentral in contact with said pipe (3) between said ends (8a, 8b). 7. Coaxial pipe insulating tubular complex according to one of claims 1 to 6, characterized in that the said longitudinallongitudinal edges of the same wall (61/62, 7i / 72) sealed against each other outwardly of the envelope are covered by an additionalmulti-layer film (13) so as to cover the edge of said longitudinal edges. 8. tubular insulating complex according to one of claims 1 to 7 characterized in that the pressure inside said envelope is less than 5 mbar, preferably less than 1 mbar. 9. Tubular complex according to one of claims 1 to 8characterized in that the insulating material (5) inside said envelope (4) is a foam of microporous synthetic material. 10. tubular insulating complex according to one of claims 1 to 9 characterized in that the foam of said microporous synthetic material is an open-cell polyurethane foam. 1 2088 30 11. Tubular complex according to one of claims 1 to 10characterized in that said tube of insulating material is constituted by unarc assembled tubes (15a, 15b), preferably half-tubes, roped against each other. 12. Isolated pipe, preferably a sub-marine pipe at great depths characterized in that it comprises tubular unit complexes (1) according to one of claims 1 to 11 Z '· placed around said pipe and connected to each other at their said ends (8a, 8b), directly or through connection elements (20a, 20b). 13. Isolated conduit according to claim 12 characterized in that said unitary tubular complexes (1) are threaded one another contrle at their said ends (8a, 8b) which are adjustedelastiquement one in the other overlapping. 14. Isolated pipe according to claim 13, characterized in that juxtapose first unitary tubular complexes (IA) having ends (8a, 8b) forming a cylinder of diameters substantially identical to that of the inner diameter of said tube of insulating material (5), and second tubular complexes (IB) having ends (8a, 8b) forming a cylinder of diameter substantially identical to that of the outer diameter of said tube of insulating material (5). 15. Insulated pipes according to one of claims 1 to 13characterized in that said unitary tubular complexes 1 have at their said ends (8a, 8b) complementary surfaces (161,163) which cooperate so that said ends of two complexesubular unitary s 'nest in one another. 16. Insulated conduits according to claim 15 characterized in that said complementary surfaces (16) comprise three-dimensional surfaces consisting of several flat surfaces (16j, I63) orthogonal to said longitudinal axis (XX ') in staircase interconnected by non-coaxial surfaces of revolution. orthogonal (I62) to said axis. 1 2088 31 17. A set of two coaxial pipes comprising an internal pipe (3) and an outer pipe (2) comprising unitary tubular complexes (1) according to one of claims 1 to 12, placed in the space between the two pipes and connected to the unspecified pipes. others at their said ends (8a, 8b), said inner pipe, and preferably said outer pipe, comprising an insulated pipe according to one of claims 13 to 16. 18. Set of two coaxial pipes according to one of Claims 13 to 17, characterized in that the said external (2) and internal (3) pipes are interconnected by mechanical links (9) preferably comprising plastic parts. , more preferably elastomer, parts against which come abut the said ends (8a, 8b) of some of said complexubundular (1). 19. Set of 2 pipes according to claim 17 or 18, characterized in that the pressure in the space between the twodondondes, outside the envelope, is less than 3 bars, preferably identical to atmospheric pressure. 20. A method of manufacturing an insulated pipe or a set of two coaxial pipes according to one of claims 13 to 19, characterized in that it comprises the steps in which: 1 / the said insulating material (5) is applied to a firstmulti-layer 10 constituting said inner wall 6 coatedon a said line, so that said insulating material 5 has a tubular shape, then 2 / covering said insulating material 5 with a second multilayer film 10 constituting said outer wall 7 del envelope 4, then 3 / said opposite ends (8a, 8b) of said complex are made by sealing said respective edges (65, 7s) of said outer and inner walls. 1 2088 32 21. A method of manufacturing a set of two ducts according to claim 20, characterized in that in step 1 / an insulating material tube 5 is made by splicing against each other around the inner pipe 3, two preformed half-tubes (15a, 15b). 22. The method of claim 20 or 21, characterized in that in step 3 /, is made at least one fold (21) in said edges (7s) at said ends (8a, 8b) of the outer wall, preferably a plurality of pleats, more preferably regularly and symmetrically spaced along the circumference of said ends (8a, 8b) of said tubular complex. 23. The method of claim 20 or 21, characterized in that in step 1 / is made beforehand folds (41) in said inner wall (6) between said edges (65) at said ends (8a, 8b) of said wall internal (6).