Process for manufacturing sealed tanks to contain gases and / or fluids

Abstract

To provide a process for manufacturing sealed tanks to contain gases and / or liquids.SOLUTION: The present manufacturing process comprises the step of forming a sealed wall of the tank, which step comprises the substep of forming an envelope by attaching at least one knitted fabric covering an outer surface of the mandrel, and the knitted fabric comprises a braided yarn of thermoplastic material that can be sealed by heat. The sub-step of filament winding a continuous section of the first strip into the envelope with a thermoplastic material that can be sealed by heat and reinforced by the fibers, thereby causing the continuous wound section of the first strip to be melted, so that a sub-step of cooling the envelope and the first strip to form a sealed wall with a single material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technical field of the present invention relates to the manufacturing process of closed tanks, i.e. sealed containers, in particular, but not exclusively, pressurized tanks made of composite materials.

[0002] The present invention relates to a manufacturing process for a closed tank using a thermoplastic material reinforced with fibers in the manufacturing process. [Background technology]

[0003]

[0003] Storage conditions for gases or liquids have improved in recent years with the advent of composite sealed tanks which have a fibrous material as their wall structure or outer envelope, ie are reinforced by fibres.

[0004]

[0004] "Sealed tank" means a tank or container that is sealed against liquids and / or gases, more precisely a tank that has a permeability to these liquids and / or these gases that is lower than the maximum limit dictated by the application.

[0005]

[0005] For example, a sealed tank designed for application in transporting hydrogen in a highly compressed form has hydrogen permeability when the gas is compressed in the pressure range of 30 MPa to 70 MPa (i.e., 300 bar to 700 bar).

[0006]

[0006] To allow hydrogen storage at these pressure conditions, it is known to use a closed tank architecture known as type III or IV, which comprises, from the inside to the outside, a closed cylinder, also known as an "inner liner" according to currently used terminology, and an outer reinforcing structure manufactured by filament winding.

[0007]

[0007] The purpose of the inner liner is primarily to ensure the gas tightness function (it should be as impermeable to hydrogen as possible). The purpose of the outer reinforcing structure is primarily to ensure the mechanical pressure resistance function.

[0008]

[0008] In type III tanks, the inner liner is made of metal. In type IV tanks, the inner liner is made of polymer and is manufactured, for example, by rotomolding or extrusion blowing.

[0009]

[0009] A new type of tank is described in document WO2011143723A2, in which the gas tightness is provided by something other than an inner metal liner. The liner is thus replaced by an inner sealing envelope formed by wrapping a covering strip made of a thermoplastic material that can be sealed by heat around a template (or mandrel) and heating it. This template is made of metal and can be disassembled into a number of hoops that fit together circumferentially, thus making it removable and reusable. The template also has a shape that corresponds to the shape of the tank. Typically, the template has a cylindrical shape and, at each axial side, has a rounded front face in the form of a cap.

[0010]

[0010] To ensure mechanical strength and to consolidate the barrier against gases, the sealed inner envelope is protected by a second envelope, known as the protective outer envelope, which can also be sealed by heat and is made from a wound strip of thermoplastic material reinforced by fibers, preferably continuous. This second envelope constitutes the outer reinforcing structure of the sealed tank.

[0011]

[0011] Like the inner envelope, this outer envelope is formed by wrapping a covering strip around the first envelope (the first envelope thus acting as a mandrel), where the material of the wrapped covering strip is a thermoplastic material reinforced by fibers. The resulting closed wall of the closed tank therefore comprises two components: the inner envelope and the outer envelope.

[0012]

[0012] An inner sealing envelope formed from a wrapped strip of thermoplastic material is much lighter and less costly than liners (which may also be made of metal or polymer), so its use makes it possible to significantly reduce the mass and cost of the tank.

[0013]

[0013] However, this advantage is weighed against an increase in the production time of the sealed tank, since winding the covering strip during the production of the sealed inner envelope takes a lot of time. In fact, the covering strip, being narrow and thin compared to the dimensions of the template and the desired thickness of the sealed inner envelope, must be wound around the template in several turns. Specifically, the covering strip is wound to form several superimposed turns that overlap longitudinally and radially, thus forming several layers around the template. Furthermore, the winding speed is limited by the stretching and the pressure that is applied to the covering strip to ensure that the first layer is well clamped to the template and that the successive layers are clamped against each other. This makes it possible to avoid air bubbles between each turn and each layer during the heating step, which allows the turns to melt or soften relative to each other and to consolidate them.

[0014]

[0014] For example, several hours are required to wind a strip with a thickness of 120 μm to 150 μm and a width of 25 mm to 80 mm on a cylindrical template with a diameter of 60 cm and a length of 3.50 m to a thickness of 2 mm to 5 mm. This type of duration slows down the development of a manufacturing process on an industrial scale.

[0015]

[0015] Therefore, there is a need to accelerate the manufacture of sealed tanks, especially sealed tanks without an inner liner. Summary of the Invention

[0016]

[0016] The present invention provides a solution to the aforementioned problems by making it possible to obtain a sealed wall in a single step of wrapping a fiber-containing material.

[0017]

[0017] A first aspect of the invention relates to a process for manufacturing a sealing wall of a closed tank, the closed tank being designed to contain a gas and / or a liquid, the manufacturing process comprising the steps of: - mounting a reusable and removable mandrel by mounting / dismounting the hoop, where the mandrel has an outer surface having a shape corresponding to the inner surface of the enclosure wall of the tank; - forming a sealing wall of the tank on the outer surface of the mandrel while forming an orifice for removal of the mandrel; - removing the mandrel from the containment wall through the removal orifice. The step of forming a sealing wall includes: - forming an envelope by applying at least one knitted item covering an outer surface of the mandrel, where the knitted item comprises a layer of yarn forming loops, the yarn being made of a thermoplastic material that can be sealed by the application of heat; - wrapping successive sections of a first strip, the first strip being capable of being sealed by application of heat and comprising a thermoplastic material reinforced by fibers, around an envelope formed by the braid covering the outer surface of the mandrel, whereby successive sections of the first wrapped strip overlap to form a first layer of the first strip and overlap to form a superimposed layer of the first strip, where the wrapping substep comprises: - applying a selected pressure to clamp against the envelope each section of the first wrapped strip forming a first layer of the first strip, and to clamp sections covering the first layer of the first strip to form other overlapping layers of the first strip; - applying a selected temperature to melt the thermoplastic material of each section of the first layer of the first strip together with the yarn underlying the envelope and melting sections of successive layers of the first strip; - cooling the envelope and the first wrapped strip to form a hermetic wall of a single material.

[0018]

[0018] Thus, the prior use of a knitted fabric, the threads / loops of which are made of a thermoplastic material compatible with the thermoplastic material of the first strip (having two components which melt under the combined effect of pressure and temperature applied during winding), advantageously makes it possible to omit the very time-consuming step of winding a strip of thermoplastic material onto a mandrel, thus making the manufacturing process of the sealing wall of the closed tank faster than the solutions presented by the prior art documents.

[0019]

[0019] In fact, the single braid (or single layer of yarn) melts together with the first strip to provide sufficient thermoplastic material to provide a barrier effect against gases while having the same mechanical pressure resistance as the sealed inner envelope of the tank according to the prior art. Since the braid is pre-manufactured, it does not have to be formed during the manufacturing process of the tank, in contrast to the sealed inner envelope of the tank according to the prior art. Also, the braid can be quickly and easily applied to the mandrel, since it can simply be fitted onto the mandrel, for example manually.

[0020]

[0020] Furthermore, due to the knitted threads / loops made of a thermoplastic material compatible with the thermoplastic material of the first strip, the resulting sealing wall is in a single piece, i.e. formed of a single material. In other words, after the wrapping with the first strip is completed, it is not possible to distinguish the components used (knitted threads and thermoplastic material impregnated with reinforcing fibers). This homogeneity of the sealing wall makes it possible to improve the strength of the tank compared to a sealing wall composed of two parts, an inner envelope and an outer envelope (such as those presented in the prior art solutions).

[0021]

[0021] Specifically, the single-piece sealed wall of the tank is more resistant than the double-layered wall when a vacuum or reduced pressure is applied inside the sealed tank, as these pressure and temperature conditions are encountered during the drying and decontamination or emptying steps of the tank, making the resulting sealed tank more suitable for use and with a longer service life.

[0022] In addition to the features set out in the preceding paragraphs, the process according to the first aspect of the invention may further comprise, taken individually or in all technically possible combinations, - the thermoplastic material of the yarn is identical to the thermoplastic material of the first strip, - Knitted fabric: 100g / m 2 ~800g / m 2 and having a mass per surface area of - the braid is in the form of one or more sleeves, each sleeve being fitted over one end of a mandrel; - the sub-step of forming the envelope also comprises applying a second braid onto the first braid, where the thermoplastic material of the yarns of the second braid can be sealed by application of heat under the same temperature and pressure conditions as the thermoplastic material of the yarns of the underlying first braid, - the sub-step of wrapping around the envelope comprises wrapping at least one other additional strip formed by the material of the first strip, where the additional strip can have one or more complementary features among which are wrapped simultaneously with the first strip.

[0023]

[0023] A second aspect of the present invention relates to a manufacturing process for a reinforced sealing wall of a tank, the manufacturing process comprising the steps of the sealing wall process described above, with or without different embodiments, comprising: - wrapping successive sections of a second strip, the second strip comprising a thermoplastic material reinforced by fibers and capable of being sealed by heat, around the sealing wall, such that successive sections of the second wrapped strip overlap to form a first layer of the second strip and overlap to form a superimposed layer of the second strip, where the wrapping substep comprises: - applying a selected pressure to clamp each section of the second wrapped strip against the containment wall to form a first layer of the second strip, and to clamp sections of the second strip that overlap the first layer to form another superimposed layer of the second strip; - applying a selected temperature to melt the thermoplastic material of each section of the first layer of the second strip together with the area underlying the sealing wall and melting sections of successive layers of the second strip; - cooling the sealing wall and the second strip to form a reinforced sealing wall made of a single material.

[0024]

[0024] The sealing wall of the tank is therefore reinforced with fibre and thermoplastic materials, which makes it possible to improve the sealing and mechanical pressure resistance of the tank.

[0025]

[0025] Advantageously, the thermoplastic material of the yarns of the knitted fabric is identical to the thermoplastic material of the first strip.

[0026]

[0026] Thus, the envelope and the second wrapped strip are joined in the most perfect way possible.

[0027]

[0027] A third aspect of the present invention relates to a process for manufacturing a closed tank for containing a gas or a liquid, the process comprising the steps of: - manufacturing a sealing wall of the tank by carrying out the steps of a manufacturing process according to the first aspect of the invention, with or without the different embodiments described above, - closing the sealing wall by attaching the bottom to the sealing wall; - consolidating the sealing wall to obtain a reinforced sealing wall of the tank, The steps for consolidating the sealing wall are: - wrapping successive sections of a second strip, the second strip comprising a thermoplastic material reinforced by fibers and capable of being sealed by heat, around the sealing wall, such that successive sections of the second wrapped strip overlap to form a first layer of the second strip and overlap to form a superimposed layer of the second strip, where the wrapping substep comprises: - applying a selected pressure to clamp each section of the second wrapped strip against the containment wall to form a first layer of the second strip, and to clamp sections of the second strip that overlap the first layer to form another superimposed layer of the second strip; - applying a selected temperature to melt the thermoplastic material of each section of the first layer of the second strip together with the area underlying the sealing wall and melting sections of successive layers of the second strip; - cooling the sealing wall and the second strip to form a reinforced sealing wall made of a single material.

[0028]

[0028] Thus, the thermoplastic material of the second strip is chemically compatible with the underlying area of ​​the sealing wall and melts therewith.

[0029] According to one embodiment, the thermoplastic material of the first strip and the thermoplastic material of the second strip are identical.

[0030] According to one embodiment, the base has a peripheral outer surface covered by a thermoplastic material that can be sealed by heat and is compatible with the thermoplastic material of the sealing wall. According to one example, the peripheral surface of the base is heated before the closing step so as to melt with the inner peripheral surface of the sealing wall that defines the extraction orifice during the step of closing the sealing wall.

[0031]

[0031] According to one embodiment, the outer surface of the bottom is covered by a second strip during said step of consolidation of the sealing wall.

[0032]

[0032] The invention and its various applications will be better understood by reading the following description and by examining the accompanying figures.

[0033]

[0033] The figures are provided as a guide and are not intended to limit the invention in any way. [Brief description of the drawings]

[0034] [Figure 1] 1 illustrates, in logic diagram form, the main steps of a manufacturing process for a closed tank according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic representation of a cross-sectional view of a closed tank obtained according to the manufacturing process depicted in FIG. 1. [Diagram 3] The main steps of the manufacturing process of the containment wall, namely the first step of the manufacturing process depicted in FIG. 1, are depicted in the form of a logic diagram. [Figure 4] 4 illustrates, in schematic form, one example of a mandrel used during the manufacturing process depicted in FIG. [Diagram 5] The second step of the manufacturing process depicted in FIG. 3 is depicted in logic diagram form. [Figure 6] 6 illustrates in schematic form an example of a knit fabric that may be used during the steps depicted in FIG. 5 . [Figure 7] 6 represents in schematic form a semi-finished containment wall produced during a first sub-step of the step represented in FIG. 5 . [Figure 8] 6 illustrates in schematic form a second sub-step of the step illustrated in FIG. 5 . [Figure 9] 6 represents in schematic form blocks forming a sealing wall surrounding the mandrel during a third sub-step of the step represented in FIG. 5 . [Figure 10] 4 represents in schematic form the confinement wall obtained after the third step of the manufacturing process represented in FIG. 3; [Figure 11] 2 represents in schematic form a semi-finished tank during a second step of the manufacturing process depicted in FIG. 1; [Figure 12] The sub-steps of the third step of the manufacturing process depicted in FIG. 1 are depicted in logic diagram form. [Figure 13] 12 depicts in schematic form a first sub-step of the step depicted in FIG. [Figure 14] 14 illustrates in schematic form an alternative sub-step to the first sub-step illustrated in FIG. [Figure 15] 13 represents in schematic form the tank obtained after a second sub-step of the step represented in FIG. 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035]

[0034] Unless otherwise specified, the same elements appearing in different figures have the same unique reference numbers.

[0036]

[0035] The present invention is in the context of closed tanks and their manufacturing process. More specifically, the object of the present invention is to more quickly manufacture closed tanks that are pressure resistant to pressures greater than 0.2 MPa and have similar or better gas barrier (permeability to the gas or liquid contained in the closed tank) characteristics than those of the prior art solutions.

[0037] An example embodiment of a closed tank manufacturing process 200 according to the present invention is illustrated in logic diagram form in FIG.

[0038]

[0037] The closed tank manufacturing process 200 is preferably used to manufacture a closed tank 1 (hereinafter also known as "tank 1"), an enlarged cross-sectional view of which is represented diagrammatically in FIG.

[0039]

[0038] In particular, the tank 1 is a composite tank designed for use in the field of transportation and distribution of hydrogen under high pressure.

[0040]

[0039] The expression "composite tank" refers to a type of tank in which the function of sealing against gas is provided by a thermosetting material and the function of mechanical pressure resistance is provided by a fiber reinforcement. The tank 1 is thus designed to contain hydrogen kept at high pressure, above 700 MPa. In this case, the tank is also designed to contain liquids such as water. It will be understood that in other examples, the tank 1 can be designed to contain other gases and / or other liquids, in conditions of atmospheric storage or under pressures lower than 700 MPa.

[0041]

[0040] As shown in Fig. 2, in this case the closed tank 1 has a cylindrical internal and external shape, in this example along a single longitudinal axis XX'. The external and internal shapes can have axes that are offset from each other, for example parallel to each other. The tank 1 is provided at each axial side 1a, 1b with a rounded side surface, known as a front surface, in the form of a dome or cap. In other examples the shape of the tank 1 may be different, for example spherical, ellipsoidal or other shape.

[0042]

[0041] In the following description, the terms "internal", "external", "inside" and "outside" are used to refer to the position of a part or surface relative to the longitudinal axis XX' of the tank 1, with (for example) an internal or inner surface being closer to the longitudinal axis than an external or outer surface. The term "axial" means "in the direction of the longitudinal axis", and the terms "radial" and "transverse" mean "in a direction perpendicular to the longitudinal axis". The term "lateral" means "on the side of a radially extending part". The terms "thickness" and "diameter" refer to dimensions measured radially. The term "length" refers to dimensions measured axially.

[0043]

[0042] More precisely, and referring again to Figure 2, the tank 1 comprises a wall 11 and an internal volume 13. In this example, the tank 1 comprises a connecting part 12.

[0044]

[0043] The internal volume 13 of the tank 1 is, in this example, 60 cm in diameter d 13 and length l of 3.50m 13 and

[0045]

[0044] The connecting part 12 of the tank 1 is for example a tap 12 making it possible to alternately close / open the passage of gas or liquid to / from the tank 1.

[0046]

[0045] The wall 11 of the tank 1 has a sealing wall 111 and, in this example, a bottom 112 located at one axial side 1b of the tank 1.

[0047]

[0046] The sealing wall 111 of the wall 11 of the tank 1 has an inner surface 111c having the shape of the internal volume 13 of the tank 1.

[0048]

[0047] The sealing wall 111 is made of a composite material, i.e. it comprises a mixture of at least one thermoplastic material and at least one fibrous material. The sealing wall 111 provides both an inner barrier effect (impermeability) to the gas or liquid contained in the internal volume 13 of the tank 1 and an effect of mechanical pressure resistance. The thermoplastic material(s) and the fiber type of the sealing wall 111 are explained below in connection with the manufacturing process 100 of the tank 1.

[0049]

[0048] The bottom 112 of the wall 11 of the tank 1 preferably has an annular shape, ie has an internal passage designed to receive the connecting piece (tap) 12.

[0050]

[0049] In the example of tank 1 illustrated in Fig. 2, the bottom 112 advantageously has a curved outer surface 112a, at least at its periphery being located within the thickness of the sealing wall 111, as will be explained below (not shown in Fig. 2), so that the sealing wall 111 and the bottom 112 forming the tank 1 form a single rigid structure capable of withstanding the pressures required by the application.

[0051] A manufacturing process 200 for the tank 1 is described below with reference to FIGS.

[0052] As shown in FIG. 1, the manufacturing process 200 for the tank 1 includes: - manufacturing the sealing wall 111 of the wall 11 of the tank 1 according to a known manufacturing process 100 according to another aspect of the invention; - a step E4 of closing the sealing wall 111 by attaching the base to the sealing wall.

[0053]

[0052] Furthermore, optionally, the process 200 also includes: - a step E5 of consolidating the sealing wall 111 to obtain a reinforced sealing wall.

[0054] A manufacturing process 100 for the confinement wall 111 is described below with reference to FIGS.

[0055]

[0054] Referring to FIG. 3, the manufacturing process 100 of the sealing wall 111 includes: - a step E1 of mounting a reusable and removable mandrel 2 by mounting / dismounting a hoop 24, the mandrel having an outer surface having a shape corresponding to the inner surface 111c of the sealing wall 111 of the wall 11 of the tank 1, a step E2 of forming a sealing wall 111 of the wall 11 of the tank 1 on the outer surface of the mandrel 2 while forming an orifice 111d for the removal of the mandrel 2; - a step E3 of removing the mandrel 2 from the sealing wall 111 via the removal orifice 111d.

[0056]

[0055] Figure 4 illustrates diagrammatically one example of an attached mandrel 2 used in the process 100. This mandrel 2 is inspired by document WO2011143723A2.

[0057]

[0056] The mandrel 2 serves as an inner mold for the sealing wall 111.

[0058]

[0057] The mandrel 2 is suitable for filament winding. Indeed, step E3 of the process 100 uses this type of process for winding a filament onto the mandrel 2, as described below.

[0059]

[0058] As shown in FIG. 4, in this case, the mandrel 2 is a hollow rotating part having a rotation axis 23.

[0060]

[0059] In this example, the mandrel 2 is provided at one end with a removable spindle (or connection) located at the axial end of the mandrel 2. In this example, the spindle 22 of this mandrel 2 is designed to be coupled to a rotation motor, making it possible to rotate the mandrel 2 about its axis of rotation 23.

[0061]

[0060] The mandrel 2 also has a removable outer surface 21 which becomes integral with the spindle 22 (after installation of the mandrel 2 has been completed).

[0062]

[0061] The outer surface 21 of the mandrel 2 has a rounded shape which corresponds to the shape (and dimensions) of the inner surface 111c of the sealing wall 111 of the wall 11 of the tank 1 (see Figure 2). Thus, according to the example of the tank 1 given above, in this case the mandrel 2 has an outer surface 21 whose maximum diameter is 60 cm and whose length is 3.50 m.

[0063]

[0062] The mandrel 2 comprises a number of hoops 24 and, in this example, a base 25. In this case, the base 25 comprises a bottom 251 and a stopper 252 located at the bottom 251, which may be formed in a single piece. The outer surface 21 of the mandrel comprises a respective outer surface 214 extending axially from each hoop 24 and an outer surface 215 of the base 25 located opposite the spindle 22 of the mandrel 2. In this example, the outer surface 215 of the base 25 comprises a bottom outer surface 2151 and a stopper outer surface 2152. Each hoop 24 is held in place by its two ends, one end fixed to the circumference 22a of the spindle 22 and the other end engaged in the bottom 251 of the base 25. According to another example, the hoops 24 can also be fitted together.

[0064]

[0063] The mandrel 2 is attached E1, for example, by first coupling the spindle 22 to a rotating tool, then engaging one end of each hoop 24 with the spindle 22, and finally fixing the opposite end of the hoop 24 to the base 25 of the mandrel 2.

[0065] It will be appreciated that other configurations of the mandrel 2 are possible (not shown).

[0066] 5 represents in the form of a logic diagram step E2 of the process 100. As mentioned above, this step E2 is intended to form the sealing wall 111 of the wall 11 of the tank 1.

[0067]

[0066] As shown in Figure 5, step E2 begins with sub-step E21, during which the braid 3 is applied to the mandrel 2 and covers the outer surface 21 of the mandrel 2.

[0068] FIG. 6 shows a schematic partial view of an example of a knitted fabric 3.

[0069]

[0068] As shown in Fig. 6, the knitted fabric 3 comprises a layer 31 of yarns 311, 312 forming loops. The knitted fabric 3 is therefore a structure that can be formed by interwoven loops or meshes. For example, the loops or meshes are formed by "interwoven head and foot". The knitted fabric 3 therefore forms a material whose mesh can stretch in different directions and has more elasticity than woven fabrics.

[0070]

[0069] The knitting yarns 311, 312 are formed by a thermoplastic material or one of the thermoplastic materials of the sealing wall 111 that can be sealed by heat (note that sealing is not performed during substep E21).

[0071]

[0070] The thermoplastic material(s) of the knitted fabric 3 is selected, for example, from among (but not limited to) polyolefin-based or polyamide-based thermoplastic materials.

[0072]

[0071] Therefore, the knitting yarns 311 and 312 may be made of nylon. In this case, specifically, the diameter of the knitting yarns 311 and 312 may be 0.5 mm to 1 mm.

[0073]

[0072] The yarns 311, 312 preferably form loops oriented in a first direction D1 and a second direction D2 perpendicular to the first direction D1. The thickness of the yarns 311, 312 and / or the geometry of the braid are such that the mass per surface area of ​​the braid 3 is less than 100 g / m2 after application to the outer surface 21 of the mandrel 2. 2 ~800g / m 2 It has been determined that:

[0074]

[0073] Thus, when substep E21 is completed, the yarns 311, 312 of the knitted fabric 3 form an envelope 30 of yarns formed according to the circumference of the outer surface 21 of the mandrel 2. In other words, the envelope 30 of yarns has the form of the circumference (of the exterior limits) of the outer surface 21 of the mandrel 2 and is positioned in contact with this outer surface 21. In other words, the envelope 30 is positioned flat or forms a net hung on the outer surface 21 of the mandrel 2.

[0075]

[0074] This envelope 30 of yarn provides a first portion of the thermoplastic material(s) of the sealing wall 111. As previously mentioned, this thermoplastic material(s) is necessary to provide a barrier effect (impermeability) to the gas or liquid contained in the internal volume 13 of the tank 1.

[0076]

[0075] Figure 7 represents the mandrel 2 obtained at the completion of step E21, in this case covered by an envelope 30 of yarn.

[0077] As can be seen from figure 7, the envelope 30 does not cover the spindle 22 of the mandrel 2. Thus, when the spindle 22 is removed during step E3 of the process 100, an orifice (corresponding to the cross section of the spindle 22), hereinafter known as the "orifice 111d for removal of the spindle 2", remains (see figure 10), through which the hoop 24 and the base 25 of the mandrel 2 can be removed from the inside of the sealing wall 111. The spindle 22 for this purpose (and thus the removal orifice 111d) has dimensions that depend on the hoop 24 and the base 251 and the stopper 252, so that they can be removed.

[0078]

[0077] In both cases, a part of the mandrel 2 is not covered by the envelope 30 to form the ejection orifice 111d. According to another example (not shown), the envelope 30 does not cover the outer surface 2152 of the stopper 252, thus allowing the stopper to be removed and forming the ejection orifice 111d or the second ejection orifice. In this example, the spindle 22 can be only the inner shaft, which is covered by 30 and can be removed through the ejection orifice 111d when the stopper is removed. In this case, the stopper 252 can act as a support and a holder for the mandrel 2, for example by making the axis 23 vertical during the manufacturing process of the sealing wall.

[0079]

[0078] In practice, the knitted fabric 3 is manufactured before carrying out the manufacturing process 100 of the closed tank 1.

[0080]

[0079] It is advantageously in the form of one or more sleeves (or socks) (not shown), which are stretchable since they are made only of yarns 311, 312.

[0081]

[0080] Thus, the sleeve is applied to the mandrel 2, for example by an operator, by fitting the sleeve onto the mandrel 2 via one of its ends, in this case via the spindle 22 of the mandrel 2, or via the base 212 of the outer surface 21 of the mandrel 2. The sleeve stretches as it is fitted, and then, upon being stretched and released, it contracts onto the outer surface of the mandrel. Thus, the braid 3 lies flat on the outer surface 21 of the mandrel.

[0082]

[0081] When the dimensions of the mandrel are large (eg, when its length is greater than 1 m), multiple sleeves are advantageously used.

[0083]

[0082] In other cases, multiple mandrels are used that are specially designed to fit different shapes (diameters) of the outer surface 21 of the mandrel 2. Thus, one sleeve can be used to cover the outer surface 214 of the hoop 24 or a portion thereof, and another sleeve can be used to cover the outer surface 215 of the base and, optionally, one or the other portion of the outer surface 214 of the hoop 24. The sleeves may be applied side by side or may overlap each other axially.

[0084]

[0083] In any case, irrespective of the number of sleeves and irrespective of the size of the mandrel (especially its length), the step E21 of applying the braid 3 is particularly quick and easy to carry out. For example, a trained operator takes 10 minutes to form the envelope 30 around the mandrel 2. In other words, the part of the thermoplastic material(s) of the sealing wall 111 is applied simply and quickly onto the mandrel.

[0085]

[0084] As a variant, another braid (not shown) can be applied to the aforementioned braid 3. This braid is hereinafter known as the "second braid", while the previously placed braid is known as the "first braid". The envelope 30 is thus constituted by two (first and second) superimposed braids. This makes it possible to increase the amount of thermoplastic material in the yarn envelope 30. This variant is particularly well suited to increasing the permeability (barrier effect against gases) of the sealing wall 111.

[0086]

[0085] When a portion of thermoplastic material has been applied to the outer surface 21 of the mandrel 2 (by the envelope 30), the objective is to apply another portion of thermoplastic material and the fibres necessary to provide the effect of a barrier to gases. This application is carried out during sub-step E22 described below in relation to Figure 8.

[0087]

[0086] During this sub-step E22, as shown in Figure 8, specifically in the inset in this Figure 8, a continuous section 41 of a first strip 4 of thermoplastic material, which can be sealed by heat and reinforced with fibers, is coiled (wrapped) around the envelope 30 of knitting yarn.

[0088]

[0087] In other words, during this substep E22, a process of filament winding of the first strip 4 onto the envelope 30 is carried out in order to cover the envelope 30 with fibres and thermoplastic material.

[0089]

[0088] The fibres of the first strip 4 are preferably continuous. This makes it possible to obtain a better functioning reinforcing structure and therefore to increase the mechanical pressure resistance of the resulting sealing wall 111.

[0090]

[0089] The fibers of the first strip 4 are formed from a material selected from the following materials: (but are not limited to) glass, carbon, metal, mineral, wool, cotton, linen, polyester, polypropylene, polyamide, basalt, Kevlar (registered trademark), expanded thermoplastic, or a mixture of two or more of these materials.

[0091]

[0090] The thermoplastic material of this first strip 4 is chemically compatible with the thermoplastic material of the yarns 311, 312. The expression "chemically compatible" means that the thermoplastic material of the knitted fabric 3 and the thermoplastic material of the first strip 4 have melting and / or softening points that are the same or within a close temperature range.

[0092]

[0091] The thermoplastic material of the first strip 4, which can be sealed by applying heat, can be identical to the thermoplastic material of the yarns 311, 312. For example, both the thermoplastic material of the first strip and the thermoplastic material of the yarns can be polyolefin-based or polyamide-based.

[0093]

[0092] The advantages brought about by the compatibility of the thermoplastic material of this first strip 4 with the thermoplastic material of the yarns 311, 312 will be explained below in relation to sub-step E23.

[0094]

[0093] The first strip 4 is preferably greater than or equal to 20 cm wide, for example greater than or equal to 50 cm, This makes it possible to carry out substep E22 more quickly than if the width of the first strip were narrower.

[0095]

[0094] It will be understood that first strips 4 having a width less than 20 cm are suitable for the process 100, for example a width of the first strips 4 equal to 2 cm, or 4 cm, or even 14 cm.

[0096]

[0095] In practice, the mandrel 2 is rotated by the spindle 22 during the execution of substep E22 in this example. According to another example, the mandrel 2 and the envelope 30 are stationary and a winding machine rotates around the mandrel 2 to filament wind the first strip 4 onto the envelope 30 in order to cover the envelope 30 with fibres and thermoplastic material. In order for the strip 4 to melt or be joined with the envelope 30 as will be explained below, the strip is clamped onto the envelope 30 and thus wound with pressure between the strip 4 and the envelope 30 during the filament winding at a temperature within a predetermined temperature range.

[0097]

[0096] As illustrated diagrammatically by the inset of FIG. 8, the continuous wound section 41 of the first strip 4 is wound in a first layer 410 of the first strip 4. 1 8, the first strip 4 overlaps to form a superimposed layer 40 of the first strip 4 (in the inset of FIG. 8, the first layer 410 is overlapped in the axial direction of the arrow). i, i=1, a second layer is being formed, superimposed on the mandrel 2 (i=1). The number n1 of superimposed layers of this first strip 4 depends on the diameter and geometry of the mandrel 2 (and therefore on the diameter and shape of the internal volume 13 desired for the tank 1) as well as on the desired burst pressure (i.e. the pressure above which the tank 1 no longer resists pressure and deforms). The number of layers n1 can be from n1=2 to several hundred, for example n1=200. The multi-layer winding makes it possible to reduce the permeability and increase the mechanical pressure resistance of the resulting 1 sealing wall 111.

[0098]

[0097] Each layer 410 i The thickness of each layer 410, i=1 to n, may be, for example, 50 μm to 300 μm. i , i=1 to n, successive sections 41 of the first strip overlap according to a variable overlap angle over a distance from 0 (corresponding to no overlap) to half the width of the first strip 4.

[0099]

[0098] During wrapping of the first strip 4, pressure and heat are applied to each successive wrapped section 41 of the first strip 4.

[0100]

[0099] The pressure applied to each section 41 of the wound first strip is determined in order to 1) clamp this section 41 against the yarn envelope 30 during the formation of the first layer 410i,i=1, and 2) clamp this section 41 against the underlying layer 410i-1 of the first strip 4 during the formation of the overlapping layers 410i,i=2 to n1.

[0101]

[0100] The heating temperature applied to each section 41 of the first wrapped strip is determined according to the properties of the thermoplastic material(s) used (for the first strip 4, for the yarn envelope 30). More precisely, the temperature is within the melting range of the thermoplastic material used (this range is common since the thermoplastic materials are compatible).

[0102]

[0101] Thus, during the formation of the first layer 410i,i=1 of the first strip 4, the thermoplastic material of each wrapped section 41 melts or bonds with the underlying yarn of the yarn envelope 30. Furthermore, during the formation of the superimposed layers of the first strip 4, the thermoplastic material of each wrapped section 41 melts or bonds with the underlying layer 410i-1 of the first strip 4.

[0103]

[0102] In other words, the temperature is selected to melt the thermoplastic material in each section of the first layer of the first strip, together with the yarn underlying the envelope of knitted yarn, and to melt sections of successive layers of the first strip.

[0104]

[0103] For example, when the thermoplastic material concerned is of the polyolefin or polyamide type, the temperature is between 160°C and 340°C.

[0105]

[0104] Under the effect of heat and clamps, the fibres of the layers 410i, i=1 to n1 of the first strip 4 are also bonded to the thermoplastic material(s) (of the yarn envelope 30 of the first strip 4).

[0106]

[0105] Thus, once substep E22 is completed, the assembly of the envelope 30 and the superimposed layers 40 of the first strip is joined, ie consolidated, into a single material.

[0107]

[0106] The expression "single material" is in this case to be understood as having such homogeneity that it is impossible to distinguish with the naked eye the materials used for their manufacture. Thus, the expression "made of a single material" refers to a monolithic structure, in contrast to a hermetic wall constituted by two concentric envelopes.

[0108]

[0107] As a variant, substep E22 is carried out not with a single first strip 4, but with at least one other additional strip formed by the material of the first strip 4, which additional strip is wound simultaneously with the first strip 4. This makes it possible to speed up the execution of this substep E22 and thus to make the manufacturing process 100 of the sealing wall 111 faster.

[0109]

[0108] The manufacturing process 100 of the sealing wall 111 also comprises a sub-step E23 during step E2. During this sub-step E23, a cooling of the assembly of the envelope 30 and the superimposed layer 40 of the first strip is carried out in order to rigidify them. This thus provides a sealing block 130 which is the sealing wall 111 of the tank 1. This block 130 is separable from the mandrel 2.

[0110]

[0109] Figure 9 illustrates the block 130 obtained at the completion of substep E23 and therefore the sealing wall 111. It should be noted that this block 130 (like the yarn envelope 30) has an exit orifice 111d located at the location of the spindle 22 of the mandrel 2.

[0111]

[0110] With reference to Figure 3, after step E2, step E3 of the manufacturing process 100 of the sealing wall 111 is carried out. This step E3 is illustrated in schematic form in Figure 10.

[0112]

[0111] As shown in Figure 10, step E3 consists of dismantling the mandrel 2 and removing it from the interior of the block 130 through the removal orifice 111d.

[0113]

[0112] In practice, during step E3, first the spindle 22 of the mandrel 2 is disassembled, then the hoop 24 is disassembled and removed through the ejection orifice 111d of the block 130, and finally the base 25 is disassembled and also removed through the ejection orifice 111d.

[0114]

[0113] Once step E3 is completed, the block 130 from which the mandrel 2 has been removed forms the sealing wall 130, 111 of the tank 1. This sealing wall 130, 111 is therefore made of a single material (see figure 10).

[0115]

[0114] Due to the integration of the yarn envelope 30 with the layer 40 of the first wrapped strip 4, the sealing walls 130, 111 have impermeability and mechanical pressure resistance properties similar to those of the tank described in document WO2011143723A2, while being faster to manufacture.

[0116]

[0115] In fact, the initial filament winding is no longer manufactured with thermoplastic material to form a layer that is a barrier to gases: this time-consuming step (more than 3 hours in the example of tank 1) is no longer necessary since it is replaced by substep E21 of process 100, which consists of forming the envelope 30 of the yarn.

[0117]

[0116] As mentioned before, this substep E21 is rapid, since the knitted fabric 3 is pre-manufactured and can therefore be applied to the mandrel 2 very quickly and easily, and finally, since a single layer of yarn 31 is sufficient to provide a sufficient amount of thermoplastic material (10 minutes are sufficient in the example of tank 1). In fact, by adapting the knitting parameters, a knitted fabric of sufficient gram weight is provided, thus making it possible to use a single layer of yarn.

[0118]

[0117] In addition to its execution speed, the joining of the yarn envelope 30 with the superimposed layer 40 of the first strip makes it possible to manufacture the sealing wall 130 in a single material. This homogeneous material has the following advantages: 1) it increases the resistance of the sealing wall 130 to internal pressure, and 2) it increases its impermeability to liquids. This therefore makes it possible to obtain a better made sealing wall 130 that is more resistant over time (or, in other words, has a longer service life).

[0119]

[0118] Finally, it should be noted that the thickness of this braid 3 is less than that of a conventional liner.

[0120]

[0119] Once the sealing wall 130 has been manufactured, the manufacturing process 200 of the tank 1 continues by carrying out steps E4 and E5 (see FIG. 1).

[0121]

[0120] Figure 11 illustrates diagrammatically step E4, the second step of the manufacturing process 200.

[0122]

[0121] As shown in Figure 11, during a step E4, the bottom 112 (see Figure 2) of the wall 11 of the tank 1 is applied against the sealing wall 130 so as to close the withdrawal orifice 111d.

[0123]

[0122] For example, the bottom 112 may be welded to the sealing wall 130 around the extraction orifice 111d. In another example, the bottom 112 may be mounted within the extraction orifice 111d.

[0124]

[0123] The internal passage of the bottom 112 has a reduced diameter compared to the diameter of the spindle 22. In this example, this internal passage is advantageously designed to receive the second spindle 6 (see FIG. 11) to enable the sealing wall 130 to rotate about its axis XX'.

[0125]

[0124] The outer periphery 112a of the bottom 112 can advantageously be formed from a thermoplastic material that can be sealed by heat and is compatible with the material of the sealing wall 130 (i.e., compatible with the thermoplastic material of the knitted yarn and therefore compatible with the thermoplastic material of the first strip 4).

[0126] For example, the base 112 may be entirely made of this thermoplastic material or may have an overmolding of this material located only around its periphery 112a (in which case the remainder of the base may be made of metal). The overmolded base may be easily welded to the enclosure wall 130.

[0127]

[0126] Figure 12 represents in the form of a logic diagram a step E5 of the manufacturing process 200 of the closed tank 1. This step E5 aims to reinforce or integrate the sealing wall 150 with a fibrous material in order to obtain a reinforced sealing wall 130 that is mechanically able to withstand a pressure of, for example, more than 2 MPa. The sealing wall 111 of the tank 1 is therefore a reinforced sealing wall 150.

[0128]

[0127] To this end, as shown in FIG. 12, this step E5 comprises a sub-step E51 of providing for the filament winding and a sub-step E52 of cooling the winding.

[0129]

[0128] Two embodiments of sub-step E51 are described below in relation to Figs.

[0130]

[0129] In the simplest embodiment illustrated in Figure 13 (hereinafter also known as the "first embodiment E51"), sub-step E51 consists of wrapping a continuous section 51 of a second strip 5 of fibre-reinforced thermoplastic material which can be sealed by heat around the sealing wall 130.

[0131]

[0130] The thermoplastic material of the second strip 5 is chemically compatible with the thermoplastic material of the first strip 4 and therefore with the thermoplastic material of the yarns 311, 312. It should be noted that the material of the second strip 5 is therefore also compatible with the thermoplastic material of the periphery 112a or outer surface of the bottom 112 (if this surface is made of a thermoplastic material).

[0132]

[0131] The second strip 5 is similar to the first strip 4 in that it may have the same width, or the same type of fibers and / or the same weave geometry.

[0133]

[0132] In practice, the sealing wall 130 can be rotated (eg via the spindle 6).

[0134]

[0133] The process of winding (or covering) the second strip 5 is similar to that of the first strip 4. Thus, as illustrated in Fig. 13, successive wound sections 51 of the second strip 5 overlap to form a first layer 510i, i = 1 of the second strip 5 and overlap to form a superimposed layer 50 of the second strip 5. The number n2 of superimposed layers depends on the dimensions of the tank 1 and can be n2 = 2 to several hundreds, for example n2 = 200.

[0135]

[0134] The multi-layer winding of the second strip 5 makes it possible to increase the permeability, mechanical strength and pressure resistance of the reinforced sealing wall 150 (and therefore the sealing wall 111 of the tank 1) compared to a winding having only the first layer 510i, i=1.

[0136]

[0135] The thickness of each layer 510i, i = 1 to n2 of the second strip 5 may be, for example, 50 μm to 300 μm. Within a single layer of the second wrapped strip, the axial overlap distance may be, for example, 0 (corresponding to no overlap) to half the width of the second strip 5.

[0137]

[0136] During the winding E51 of the second strip 5, pressure and heat are applied to each wound section 51, as during the winding E22 of the section 41 of the first strip 4.

[0138]

[0137] More specifically, the pressure applied to each section 51 of the second wrapped strip is - 1) clamping this section 51 against the outer boundary of the containment wall 130; 2) it is determined in order to clamp this section 51 against the underlying layer 510i, i=1 to n2 of the second strip (during the formation of the superimposed layer of the second strip 5);

[0139]

[0138] The temperature of the heat applied to each wrapped section 51 of the second strip may be the same as the temperature applied during the winding of the first strip 4. Alternatively, the temperature of the heat applied to each wrapped section 51 of the second strip is close to, i.e. within, the melting temperature range of the thermoplastic material used.

[0140]

[0139] Thus, the thermoplastic material of each wrapped section 51 of the second strip 5 melts together with the area underlying the sealing wall 130 and (during formation of the overlapping layers of the second strip) melts together with the underlying layer of the second strip.

[0141]

[0140] Once sub-step E51 is completed, the superimposed layer 50 of the second strip 5 is joined to the sealing wall 130 to form a reinforced sealing wall 150 made of a single material.

[0142]

[0141] During substep E52, the second wrapped strip and the sealing wall 130 are cooled and therefore rigidified in order to consolidate and become rigid the reinforced sealing wall 150 which thus forms the sealing wall 111 of the tank 1.

[0143]

[0142] Cooling can be carried out after substep E51, ie after the winding of the second strip 5 is completed.

[0144]

[0143] Alternatively, the cooling may be performed locally during the winding E51 of the second strip 5.

[0145]

[0144] The cooling E52 can be performed in a regulated manner by injecting cooling water inside the sealing wall 130 and / or by applying pressure to the inner surface of the sealing wall 130.

[0146]

[0145] Figure 14 represents a preferred embodiment E511 of substep E51. According to this preferred embodiment, substep E511 consists of wrapping a successive section 51 of the second strip 5 not only around the sealing wall 111 but also around the outer surface 112a of the bottom part 112.

[0147]

[0146] Thus, once sub-step E511 is completed, the superposed layer 50 of the second strip 5 also overlaps the outer periphery 112a of the bottom part 112.

[0148]

[0147] Once the periphery 112a of the bottom part has been covered with a thermoplastic material that is compatible with the thermoplastic material of the sealing wall 111, the superposed layer 50 of the second strip 5 is bonded to the sealing wall 111 and to the periphery 112a of the bottom part 112. Thus, the reinforced sealing wall 150 (and therefore the sealing wall 111 of the tank 1) extends to the circumference of the spindle 6 and is formed by a single material.

[0149]

[0148] After carrying out cooling E521, according to the process previously described in relation to substep E52, the structure illustrated in FIG. 15 is obtained.

[0150] 15, according to the preferred embodiment E511, the reinforced sealing wall 150 (and therefore the sealing wall 111 of the tank 1) extends up to the periphery of the internal passage of the base 112. In other words, the base 112 is partially integrated into the thickness of the sealing wall 111. This makes it possible to prevent a pressure-tight rupture around the tap of the tank 1 and thus to obtain a tank 1 that is sealed and mechanically pressure-resistant to the relevant pressures.

[0151]

[0150] It should be noted that the sealing wall 111 of the tank 1 obtained by carrying out substep E511 is advantageously more homogeneous than that obtained according to the first embodiment E51. This sealing wall 111 is thus in fact formed by the same reinforcing material over its entire periphery. This makes it possible to obtain a tank 1 with impermeability and mechanical properties that are identical at all points of its sealing wall 111. This (spatial) homogeneity of the sealing wall 111 makes it possible to produce a better made tank 1.

[0152]

[0151] Finally, after step E5, the process 100 may comprise a step (not shown) consisting of fitting the taps 122 of the connecting parts 12 of the tank 1 to the internal passages of the bottom 112. The tank 1 illustrated in Figure 2 is thus obtained.

Claims

1. A manufacturing process (100) for a sealing wall (111) of a closed tank (1), said closed tank (1) being designed to contain a gas and / or a liquid, said manufacturing process (100) comprising: - a step (E1) of mounting a reusable and removable mandrel (2) by mounting / dismounting a hoop (24), said mandrel (2) having an outer surface (21) having a shape corresponding to the inner surface of said sealing wall (111) of said sealed tank (1), - forming (E2) the sealing wall (111) of the sealed tank (1) on the outer surface (21) of the mandrel (2) while forming an orifice (111d) for the removal of the mandrel (2); a step (E3) of removing said mandrel (2) from said sealing wall (111) through said removal orifice (111d); Equipped with The step (E2) of forming the sealing wall (111) comprises: - a substep (E21) of forming an envelope (30) by applying at least one braid (3) covering said outer surface (21) of said mandrel (2), said braid (3) comprising layers of yarns (311, 312) forming loops, said yarns (311, 312) being made of a thermoplastic material that can be sealed by applying heat; a substep (E22) of wrapping successive sections (41) of a first strip (4) comprising a thermoplastic material reinforced by fibers and capable of being sealed by the application of heat, around the envelope (30) formed by the braid (3) covering the outer surface (21) of the mandrel (2), so that the successive sections (41) of the first wrapped strip (4) overlap to form first layers (410i, i=1) of first strips and overlap to form superimposed layers (40) of first strips, wherein the wrapping substep (E22) comprises: - applying a selected pressure to clamp each section (41) of the first wrapped strip forming the first layer (410i, i=1) of a first strip against the envelope (30), and to clamp the sections covering the first layer of the first strip to form the other superimposed layer (40) of first strip; - applying a temperature selected to melt the thermoplastic material of each section (41) of the first layer of the first strip together with the yarns (311, 312) underlying the envelope (30) and to melt the sections of the successive layers of the first strip; Conducted by a substep (E23) of cooling said envelope (30) and said first wrapped strip (4) in order to form said sealing wall (130) in a single material; The method of manufacturing a sealing wall (100) is carried out by carrying out the steps:

2. 2. The process (100) for manufacturing a containment wall according to claim 1, wherein the thermoplastic material of the yarns (311, 312) is the same as the thermoplastic material of the first strip.

3. The knitted fabric (3) is 100 g / m ２ Up to 800 g / m ２ 3. The process (100) for manufacturing a confinement wall according to claim 1 or 2, wherein the confinement wall has a mass per surface area of ​​0.1 to 0.5 mm.

4. The process (100) for manufacturing a containment wall according to any one of claims 1 to 3, wherein the braid (3) is in the form of one or more sleeves, each sleeve being fitted onto one end of the mandrel.

5. The process (100) for manufacturing a sealing wall according to any one of claims 1 to 4, wherein the substep (E21) of forming the envelope (30) also comprises applying a second braid onto the first braid (3), wherein the thermoplastic material of the yarns of the second braid can be sealed by applying heat under the same temperature and pressure conditions as the thermoplastic material of the yarns of the underlying first braid (3).

6. The process (100) for manufacturing a containment wall according to any one of the preceding claims, wherein the substep (E22) of wrapping the envelope comprises wrapping at least one other additional strip formed by the thermoplastic material of the first strip, wherein the additional strip is wrapped simultaneously with the first strip.

7. A process (200) for manufacturing a closed tank for containing a gas or a liquid, comprising: - manufacturing a sealing wall (130) of said closed tank (1) by carrying out steps (E1, E2, E3) of the manufacturing process (100) according to any one of claims 1 to 6, a step (E4) of closing said sealing wall (130) by attaching a bottom (112) to said sealing wall (130); a step (E5) of consolidating said sealing wall (130) to obtain a reinforced sealing wall (150, 111) of said closed tank (1); Equipped with The step (E5) of consolidating the sealing wall (130) comprises: a sub-step (E51, E511) of wrapping successive sections (51) of a second strip (5) comprising a thermoplastic material reinforced by fibers and capable of being sealed by heat, around said sealing wall (130), so that said successive sections (51) of the second wrapped strip overlap to form first layers (510i, i=1) of the second strip (5) and overlap to form superimposed layers (50) of the second strip (5), wherein said wrapping sub-steps (E51, E511) comprise: applying a selected pressure to clamp each section (51) of the second wrapped strip forming the first layer (510i, i=1) of the second strip against the sealing wall (130) and to clamp the sections that overlap the first layer of the second strip to form the other superimposed layer of the second strip; - applying a selected temperature to melt the thermoplastic material of each section of the first layer of the second strip together with the area underlying the sealing wall (130) and to melt the sections of the successive layers of the second strip; Conducted by a substep (E52) of cooling said sealing wall (130) and said second strip (5) to form said reinforced sealing wall (130, 111) made of a single material; The manufacturing process (200) of the closed tank is carried out by carrying out

8. 8. The process (200) for manufacturing a closed tank according to claim 7, wherein the thermoplastic material of the first strip and the thermoplastic material of the second strip are the same.

9. 9. The process (200) for manufacturing a closed tank according to claim 7 or 8, wherein the bottom (112) has a peripheral outer surface covered by a thermoplastic material that can be sealed by heat and is compatible with the thermoplastic material of the sealing wall (130).

10. Manufacturing process (200) of a closed tank according to any one of claims 7 to 9, wherein the outer surface of the bottom (112) is covered by the second strip during the step (E5) of consolidating the sealing wall (130).

Images