FR2947031A1 - Fluid transport apparatus e.g. fluid transport pipe, manufacturing process, involves introducing inner tube into cavity of shell of fluid transport apparatus e.g. fluid transport pipe, by forced fitting or interlocking - Google Patents

Abstract

The process involves introducing an inner tube (21), made of a plastic material, into a cylindrical cavity of a cylindrical shell (20) of a fluid transport apparatus e.g. fluid transport pipe, by forced fitting or interlocking. The cavity is destined to receive the tube, and the tube or shell is maintained at ambient temperature. Insertion force is exerted on one of tube and shell made of plastic, according to a common longitudinal axis (26) where value of the force is in a range from 103 Newton to 105 Newton. The tube is cooled before insertion of the tube into the cavity. An independent claim is also included for an apparatus for transporting fluid.

Description

FIELD OF THE INVENTION The present invention relates to fluid transport apparatus having a double wall and to methods of manufacturing such apparatus. The invention relates in particular to the tubes or conduits for transporting fluid, to the accessories for these tubes or ducts, such as valves, T-shaped or L-shaped bifurcating members hereinafter designated by tee, valves, or tubular sleeves, and cylindrical pump bodies for conveying a fluid. The invention is particularly applicable to conduits, pumps, and accessories for transporting water, in particular brackish water or seawater. STATE OF THE ART For the transportation of corrosive fluids in particular, it is known to use a double-walled tube including an inner wall provided to resist corrosion, and an outer wall provided to ensure the mechanical strength of the tube, especially in the case where the transported fluid is under pressure. It is possible to manufacture a double-walled tube by casting a fluid material into a tube forming the outer wall, as described in the patent FR431421 for example. Another solution is to introduce two tubes into each other. FR1095062 patent proposes to fit a plastic tube in a metal tube with a diametrical clearance, to compress axially the plastic tube so that it marries the metal tube, and to stretch the assembly to the shrink and ensure the Tangential compression of the plastic tube. FR1498725 patent proposes to heat a plastic tube before introducing it with a small clearance in a metal tube which is then stretched to shrink and ensure the connection between the two tubes. The known methods for making double-walled tubes - or composite tubes - are generally complex and expensive to implement. These methods do not generally make it possible to obtain a composite tube of large diameter. These methods do not make it possible to manufacture bodies of tees, valves, or other non-cylindrical accessories. SUMMARY OF THE INVENTION An object of the invention is to provide a method of manufacturing fluid transport or pumping apparatus which makes it easy to manufacture these devices. It is an object of the invention to provide a method of manufacturing double-walled fluid transport conduits and accessories which is improved and / or which at least partially overcomes the shortcomings or disadvantages of known methods. It is an object of the invention to provide double-walled fluid conveying conduits and accessories which are improved and / or which at least partially remedy the shortcomings or disadvantages of known double wall pipes and fittings. According to one aspect of the invention there is provided a method of manufacturing a fluid transport (or pumping) apparatus into which a plastic tube or jacket is introduced into a cylindrical cavity of an envelope. (of the device), by fitting - or interlocking - forced. For this purpose, the tube and the cavity of the envelope intended to receive the tube are aligned, a first of the two parts (tube or envelope) is maintained and an insertion force is exerted on the second part, substantially according to their common longitudinal axis. The value of the insertion force (or support) required to obtain the fitting varies depending in particular on the nature of the materials constituting the two parts, the diameter of the tube, and its adjustment in the envelope. This value can be in a range from about 103 Newton (N) to about 106 N. This effort can be exerted by a hydraulic press for example.

The fitting of the jacket in the envelope is generally made cold, that is to say without heating the envelope. The plastic tube can be cooled - or reheated - before it is inserted into the cylindrical cavity of the envelope to reduce its outside diameter and the necessary insertion effort.

According to a preferred embodiment, the pre-cooled plastic tube is pressed into the envelope maintained at ambient temperature. In particular, it is possible to cool the plastic tube to a temperature below the temperature of the jacket by several tens of degrees Celsius (° C), especially down to a temperature of about 20 ° C. 40 ° C or 60 ° C, at the temperature of the envelope. It is also possible to coat the outer surface of the plastic tube or the inner surface of the envelope cavity with a solid, liquid, pasty or gelatinous material which promotes the mutual sliding of the respective surfaces of the tube and of the envelope which are brought into mutual contact during the fitting. This material may be a product based on silicone or polytetrafluoroethylene, for example. It is also possible to form a chamfer (of small size) at the periphery of one end of the tube through which it is introduced into the envelope, or else at the end of the cylindrical cavity through which the tube is fitted, in order to to facilitate the introduction of the tube into the cavity of the envelope. After fitting, if necessary the composite tube 30 is cut to the desired length. Then at least one end face of the plastic tube is formed, where appropriate the two end faces of the tube.

Preferably, a housing is then formed for a seal in the vicinity of the upright end (where appropriate adjacent each end). More preferably, such a housing is formed which has a peripheral opening which extends in a diameter greater than the outer diameter of the casing receiving the plastic tube. According to one embodiment, the seal housing may be formed in a rib projecting from an external projection at one end of the plastic tube and extending out of the casing, the rib being integral with the plastic tube. However, according to a preferred embodiment, forming the seal housing on an annular piece which is secured to one end of the plastic tube. This securing can be obtained by welding the annular piece to the end of the plastic tube, the annular piece being made of a material provided for this purpose, in particular in a thermoplastic material identical or similar to that constituting the tube. This weld can be obtained by melting / softening the zones facing each other of the two parts to be welded, and if necessary by exerting a mutual support force on the areas to be welded. The melting (softening) of the plastic material can be achieved by sweeping these areas with a stream of hot air, heating these areas by infra-red radiation, and / or by mutual friction of the zones. welding. This can also be obtained by means of a heating insert placed in contact with the zones of the parts to be welded and comprising an electric circuit traversed by a current of sufficient intensity to melt / soften the insert and the plastic of the zones. respective parts to be welded. A flange (fixed or pivotal) is also generally attached to the end of the casing to facilitate attachment of the apparatus to another apparatus.

For the manufacture of a fluid transport apparatus delimiting two distinct (non-aligned) cylindrical cavities, such as a tee or elbow, it is possible to introduce a first tube - or jacket - of plastic material into a first tubular cavity of the envelope of the apparatus, by fitting - or interlocking - forcefully, then introduce a second tube - or jacket - of plastic in a second tubular cavity, by fitting - or interlocking - forcefully, substantially until the first tube is contacted, then make a tight connection between the two tubes in their region of contact - or proximity - mutual (the).

The connection between the tubes is preferably carried out by welding, by causing the two tubes to soften in their portions in contact or mutual proximity (1c), bringing into mutual contact and / or a mixture of the soft plastic material of the two tubes, then a cooling and hardening of this material, to form the sealed connection. For this purpose, the respective adjacent (junction) regions of the two tubes may be subjected to a stream of air - or other fluid - sufficiently hot to cause softening of the plastic material of these joining regions, or to infrared radiation.

Alternatively or in addition, it is possible to cause the softening and welding - electro-welding - of the tubes by Joule effect, as indicated above concerning the connection of the annular piece to the end of the plastic tube. For this purpose, one of the plastic tubes may be inserted in one or the other region of the tubes intended to be placed in mutual contact, a heating element - or an electro-fuse insert - comprising a circuit resistive provided to heat the element and cause softening or melting of the plastic material of these regions - and if necessary the insert - when the resistive circuit is crossed by an electric current of sufficient intensity. Alternatively, this element or heating insert can be placed in the casing of the device, in contact with the first plastic tube previously fitted, before introduction of the second tube into the casing. In order to weld the two tubes together, a mutual support force can be exerted on them in a direction substantially corresponding to the longitudinal axis of the second tube. In order to avoid deforming the first tube by exerting this support, it is possible to insert inside this tube, before exerting the support, a force distribution structure which preferably marries at least a part of the inner face of the first tube. This force distribution structure may take the form of a cylindrical mandrel whose outer diameter is less than the inside diameter of the first tube. The tube (s) of thermoplastic material may for example consist of polyethylene, polypropylene, polyvinyl chloride, polyamide, or polytetrafluoroethylene. The envelope may be made of metal, in particular steel, or of a plastic material reinforced with fibers, in particular carbon fibers. The invention makes it possible, in particular, to manufacture conduits and accessories having a diameter ranging from about 10-1 meter (m) to about one meter, having a length ranging from about 10-1 m to about 10-1 m. m about, and having a thickness in a range of about 2.10-2 m to about 10-1 m. Preferably, the thickness of the inner tube is at least equal to the thickness of the outer shell. According to another aspect of the invention, there is provided a fluid transport apparatus, which comprises an envelope delimiting two cylindrical cavities extending along two oblique (distinct) longitudinal axes, in particular along two orthogonal longitudinal axes, and which comprises two tubes of thermoplastic material respectively fitted into the cavities, which are connected by a sealed connection.

Other aspects, features, and advantages of the invention appear in the following description which refers to the appended figures and illustrates, without any limiting character, preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic longitudinal sectional view of a tube and a cylindrical envelope for the production of a duct according to one embodiment of the invention. FIG. 2 is a schematic longitudinal sectional view of the respective longitudinal ends of the tube and the casing of FIG. 1, and is an enlarged view of the detail II of this FIG. 1. FIG. 3 is a longitudinal sectional view schematic of a duct blank obtained by forced fitting of the parts of Figures 1 and 2.

Figure 4 is a schematic longitudinal sectional view of a duct and an annular piece to be welded at one end of the duct. Figure 5 is a schematic longitudinal sectional view of the duct and the annular part of Figure 4, after their mutual interlocking.

FIG. 6 is a diagrammatic longitudinal sectional view of the duct obtained by welding the parts of FIGS. 4 and 5. FIG. 7 is a diagrammatic longitudinal sectional view of an envelope equipped with a fitted tube and a second tube with press into a second cylindrical cavity of the envelope to form a T-shaped connection accessory. FIG. 8 is a schematic side view of the second tube of FIG. 7 and is a view along line VIII of this FIG. 7. FIG. 9 is a schematic longitudinal sectional view of the casing and the second tube of FIGS. 7 and 8 after their mutual interlocking. FIG. 10 is a schematic longitudinal sectional view of an accessory obtained by welding the parts of FIGS. 7 to 9.

Figure 11 is a schematic longitudinal sectional view of an accessory obtained from the parts of Figures 7 to 9 and annular seal supports, according to another embodiment. FIG. 12 is a schematic longitudinal sectional view of an accessory obtained from the parts of FIGS. 7 to 9 and including a closure plug, according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION Unless otherwise explicitly or implicitly stated, elements or members - structurally or functionally - identical or similar are designated by identical reference numerals in the various figures. With reference to FIGS. 1 to 4 in particular, the invention makes it possible in particular to manufacture a double-walled tubular conduit 60 which comprises a rectilinear section 21 of thermoplastic tube 15 which is pressed tight into a straight section 20 of metal tube . For this purpose, tube sections 20, 21 whose respective lengths 25, 24 (FIG. 1) are substantially equal are used; in addition, the nominal outside diameter 22 of the inner tube 21 is chosen to be equal to the nominal inside diameter 23 of the outer tube 20. Before the fitting - or interlocking - of the tube 21 into the tube 20 is carried out, a chamfer 29 at the periphery of the end of the tube 21 through which it is introduced into the casing 20, and a chamfer 28 is preferably formed at the end of the cylindrical cavity 37 of the casing 20 through which the tube 21 is fitted (Figure 2). The outer surface 30 of the tube 21 and / or the inner surface 27 of the envelope 20 delimiting the cavity 37 is then preferably coated with a material promoting the mutual sliding of the respective surfaces 30, 27 of the tube and of the tube. envelope which are brought into mutual contact during fitting, such as PTFE.

The plastic tube 21 is then cooled to reduce its outside diameter and the necessary insertion force, for example to a temperature ranging from minus 20 ° C to 0 ° C (zero degrees Celsius). ) approximately, the temperature of the casing 20 being for example close to the ambient temperature, is in a range from about 10 ° C to about 40 ° C. The tube 21 and the cavity 37 of the envelope 20 for receiving the tube 21 are then aligned so as to substantially confuse their respective longitudinal axes along the axis 26; one of the two parts - tube 21 or casing 20 - is then maintained and an insertion force 32 (FIG. 1) is exerted on the second part, substantially along their common longitudinal axis 26. The value of the insertion force 32 necessary to obtain the fitting can be close to 104 N approximately to 106 N approximately.

The thickness 69 of the wall of the tube 21 may be in a range from about 2 millimeters (mm) to about 100 millimeters, particularly in the range of about 5 millimeters (mm) to about 50 millimeters. The thickness 70 of the wall of the envelope 20, which is generally less than the thickness 69, may be in the range of about 1 millimeter (mm) to about 50 mm, in particular in the range of 2 or about 3 millimeters (mm) to about 20 or 30 mm. When the length of the conduit or accessory to be produced is less than that of the tube blank obtained by these operations, the resulting composite tube blank is cut to the desired length. In order for the respective end faces of the inner tube and the outer tube to be coplanar, the end face (s) 33, 34 of the plastic tube 21 and, where appropriate, the (or the end face (s) of the casing tube 20.

A housing for a seal may then be formed near each end of the inner tube.

Such an annular housing 41, 42 may be provided on the end face 33, 59 of the inner tube 21, 51, or on a bore - or shoulder - 35 formed on the inner cylindrical face 36 of the tube 21, as illustrated in FIG. 12.

According to another embodiment illustrated in FIGS. 4 to 6 and 11, a seal housing 40 is formed which has a peripheral opening which extends in a diameter greater than the outside diameter of the envelope, in a rib 43 forming an external projection. at one end of the tube 21 and extending out of the envelope 20.

The rib 43 is integrated in an annular piece 44 pierced with a bore 58, which can be secured to the end 33 of the tube 21. For this purpose, the piece 44 comprises a tubular end portion 46 provided for s interlocking with play in an annular groove - or shoulder - 35, 45 formed at the end 33 of the tube 21, as shown in Figure 5. The joining of the parts 21 and 44 is obtained by welding the annular piece at the end of the plastic tube, the annular piece being made of a thermoplastic material identical or similar to that constituting the tube.

The welding is obtained by melting or softening the zones 35, 45, 46 facing each other of the two parts to be welded, and possibly exerting a mutual support force on the areas to be welded. The melting or softening of the plastic material may be obtained, in particular by sweeping the zones to be welded by a stream of hot air, or by heating these zones by means of a heating insert placed in contact with the zones parts to be welded and having an electric circuit 47 crossed by a current of sufficient intensity. In the embodiment illustrated in FIGS. 4 and 5, the circuit 47 consists of an electrically conductive wire wound on the outer face 57 of the portion 46 of the part 44, and whose two ends 61 and 62 can be connected to a electric power source (not shown) such as a DC generator. After cooling and hardening of the softened plastic material, the portions 61, 62 of wire are detached (cut), the turns of the circuit 47 remaining embedded in the plastic material constituting the welded portions, as shown in FIG. 6. With reference to FIGS. In particular, for the manufacture of an apparatus such as a T-connector delimiting two distinct cylindrical cavities 37, 50, whose respective longitudinal axes 26, 39 intersect for example at a point 63 (FIG. a first plastic tube 21 in the first tubular recess 37 of the T-shaped casing 64 of the apparatus, by press-fit or snap fit, as described above. A second tube - or sleeve or sleeve - 51 made of plastic material is then introduced into the second tubular cavity 50, by fitting - or interlocking - also forced substantially until contact with the outer face 30 of the first tube 21 is made. , the lower face 65 of the tube 51 is in the form of a cylindrical cap having the same diameter as the outside diameter of the tube 21, 20 as illustrated in FIG. 8. A sealed connection is then made between the two tubes 21, 51, in their region of contact. - or proximity - mutual (the) 52, 53, by welding, causing softening of the two tubes in these regions / portions 52, 53 in contact or mutual proximity (1c), mutual contacting and / or mixing soft plastic material of the two tubes, then cooling and hardening of this material. For this purpose, as previously indicated, the respective adjacent junction regions of the two tubes can be subjected to a stream of air sufficiently hot to cause softening of the plastic material of these joining regions. However, according to a preferred embodiment, the tubes are softened and welded by the Joule effect, by means of a heating element comprising a resistive circuit 54 traversed by an electric current, as described previously for the welding of the parts. 21 and 44. For this purpose, the circuit 54 may form one or more turns on the surface of the lower end 65 of the tube 51, and extend by two portions 61, 62 (Figure 7) wire used to connect the circuit 54 to an electric generator. In order to weld the two tubes 21, 51 to each other, a tubular / cylindrical mandrel-shaped force distribution structure 55 is preferably inserted inside the first tube 21, which follows the internal face 36 of the tube. tube 21, then exerted on the tubes 48 a mutual support force in a direction substantially corresponding to the longitudinal axis 39 of the tube 51, as shown in Figure 9. This allows to exert a substantial effort 48 without damaging the tube 21. After extracting the mandrel 55 from the cavity 37 and having eliminated the portions of wire 61, 62, an opening 56 is drilled in the wall of the tube 21, at the lower end of the tube 51, in order to make the cavities communicate. cylindrical 38, 66 that the tubes 21, 51 delimit 20 respectively, as shown in Figure 10. It can then equip the casing 64 with flanges 67, and weld seal door parts to the ends of the tubes 21, 51 to obtain an accessory 19 such illustrated in Figure 11. On may also, as illustrated in FIG. 12, form an elbow-shaped accessory 19, by closing one end of the composite tube 21, 64 by a disc-shaped pad 68, a thickened central portion 71 of which is fitted into a groove 35 formed The invention also makes it possible to produce valve bodies, valves, and piston pumps.

Many embodiments are within the scope of the appended claims; in particular, the heating insert 47, 54, 61, 62 can be produced as described in patent FR2868007.

Claims (19)

Claims 1 - A method of manufacturing a fluid transport apparatus (19, 60) characterized in that a plastic tube (21, 51) is introduced into a cylindrical cavity (37, 50) of an envelope (20). , 64) of the appliance, by fitting - or fitting - forced. 2- A method according to claim 1 wherein aligning the tube and the cavity of the envelope for receiving the tube, maintains a first of two parts -tube or envelope- and exerts an insertion force (32) on the second piece, substantially along their common longitudinal axis (26, 39), the value of the insertion force necessary to obtain the fitting being in a range from 103 Newton (N) to about 106 N approximately. 3- A method according to claim 1 or 2 wherein the plastic tube is cooled before insertion into the cylindrical cavity of the envelope maintained at ambient temperature, to a temperature below the temperature of the envelope of several tens of degrees Celsius (° C), to reduce its outside diameter and the necessary insertion effort. 4. Method according to any one of claims 1 to 3 wherein is coated the outer surface (30) of the plastic tube or the inner surface (27) of the cavity of the casing, a material promoting sliding of the respective surfaces (30, 27) of the tube and of the envelope which are brought into mutual contact during the fitting, and a chamfer (28, 29) is formed at the periphery of one end of the tube by which the It is introduced into the envelope, and / or at the end of the cylindrical cavity through which the tube is fitted, in order to facilitate the insertion of the tube into the cavity of the envelope. 5- A method according to any one of claims 1 to 4 wherein optionally intersecting the composite tube obtained to the desired length, is raised at least one end face (33, 34) of the plastic tube, and forming a housing (40 to 42) for a seal, in the vicinity of the erected end. 6. The method of claim 5 wherein said housing (40) is formed which has a peripheral opening which extends in a diameter greater than the outer diameter of the casing, in a rib (43) making an external projection at one end. the plastic tube and extending out of the casing, the rib being integral with an annular piece (44) which is secured to one end of the plastic tube. 7- A method according to claim 6 wherein the fastening of the annular piece is obtained by welding at the end (33, 34) of the plastic tube, the annular part being made of a thermoplastic material identical or similar to that constituting the tube , the welding being obtained by melting or softening the areas (45, 46) facing each other of the two parts to be welded, possibly exerting a mutual support force on the areas to be welded. 8- The method of claim 7 wherein the melting or softening of the plastic material is obtained by sweeping the areas to be welded by a stream of hot air, by heating these areas by radiation, friction, or via a heating insert placed in contact with the zones of the parts to be welded and comprising an electric circuit (47, 54) traversed by a current of sufficient intensity. 9- A method according to any one of claims 1 to 8 for the manufacture of an apparatus defining two cavities (37, 50) cylindrical, wherein is introduced a first tube (21) of plastic material in a first cavity (37). ) tubular of the casing of the device, by fitting - or interlocking - forcefully, is then introduced a second tube - or jacket - (51) of plastic in a second cavity (50) tubular, by fitting - or interlocking - forced, substantially until the first tube is contacted, then a sealed connection is made between the two tubes in their region of contact - or mutual proximity - (the), by welding, causing a softening of the two tubes in their portions (52). 53) in contact or mutual proximity (1c), mutual contacting and / or mixing of the soft plastic material of the two tubes, followed by cooling and hardening of this material, to form the sealed connection. 10- The method of claim 9 wherein subjecting the junction regions - (52, 53) respective respective of the two tubes to a stream of air hot enough to cause the softening of the plastic of these junction regions. 11- A method according to claim 9 or 10 wherein the softening and welding of the tubes by Joule effect, by means of a heating element having a resistive circuit (54) traversed by an electric current. 12- A method according to any one of claims 9 to 11 wherein, for welding the two tubes to one another is inserted inside the first tube structure (55) distribution force effort at least a portion of the inner face (36) of the first tube, and then exerted on the tubes a force (48) of mutual support in a direction substantially corresponding to the longitudinal axis (39) of the second tube. 13- A method according to any one of claims 9 to 12 wherein an opening (56) in the wall of the first tube is drilled at the end of the second tube. 14. Apparatus (19) for conveying fluid, which comprises an envelope (20, 64) delimiting two cylindrical cavities (37, 50) extending along two oblique longitudinal axes (26, 39), in particular along two orthogonal longitudinal axes. , characterized in that it comprises two tubes (21) of thermoplastic material respectively fitted into the cavities (37, 50) and connected by a fluid-tight connection. 15- Apparatus according to claim 14 which comprises an electric circuit (47, 54) embedded in the region (52, 53) of junction of the two tubes. 16. Apparatus according to claim 14 or 15 wherein the tubes (21) consist of polyethylene, polypropylene, polyvinyl chloride, polyamide, or polytetrafluoroethylene. 17- Apparatus according to any one of claims 14 to 16 wherein the envelope is made of metal. 18- Apparatus according to any one of claims 14 to 16 wherein the casing is made of a fiber reinforced plastics material. 19- Apparatus according to any one of claims 14 to 18 wherein the thickness (69) of the tubes is greater than the thickness (70) of the casing.