NL2036119B1

NL2036119B1 - Multiple branch electrofusion fitting

Info

Publication number: NL2036119B1
Application number: NL2036119A
Authority: NL
Inventors: Stammes Erik; Jeroen Cloos Peter
Original assignee: Soluforce B V
Priority date: 2023-10-25
Filing date: 2023-10-25
Publication date: 2025-05-07
Also published as: WO2025089952A1

Abstract

P62003207NL A multiple branch electrofusion ﬁtting for connecting three pipe sections, the multiple branch electrofusion fitting comprising a housing comprising three ends arranged to respectively connect to the three pipe sections, and three electrofusion branches, the three electrofusion branches respectively connected to the three ends and comprising a locking system, an inner bush and an outer bush Wherein the inner bush comprises resistance Wires and thermoplastic material, the locking system arranged to mechanically secure the outer bush to the inner bush, and Wherein the resistance Wires can be connected to an electric power source for melting a surface of the inner bush. 10 [Fig. 1]

Description

P62003207NL 1

MULTIPLE BRANCH ELECTROFUSION FITTING

FIELD OF THE INVENTION

[001] The invention relates to a multiple branch electrofusion fitting for pipes transporting fluid, and a method of manufacturing a multiple branch electrofusion fitting. The invention further relates to an assembly comprising a multiple branch electrofusion fitting, and multiple pipe sections of a high- pressure pipe, and a method for providing an assembly.

BACKGROUND OF THE INVENTION

[002] Electrofusion is a technique used to connect pipes made of thermoplastic material.

Prefabricated fittings comprising resistance wires are commonly used. These resistance wires can be connected to an electric power source for melting the surfaces of the fitting and those of each pipe section. However, when connecting more than two pipe sections, electrofusion faces some shortcomings such as non-axial loads that can cause shear strength.

[003] US 11,543,064 B2 discloses a system to connect three pipes using electrofusion wherein a threaded pattern is formed in an outer surface of the coupler housing, gripping wedges are affixed to the coupler housing, a nut is attached to the coupler housing engaging with the threaded pattern and compressing the wedges against the connecting pipes to provide axial load transfer from the connecting pipes to the coupler housing via the wedges. However, this is a complex structure that needs the nuts to be affixed after inserting the pipes in the coupler housing and also needs a hole for the nut aligned with the electrical wires.

SUMMARY OF THE INVENTION

[004] According to a first aspect, a multiple branch electrofusion fitting for connecting three pipe sections is provided. The multiple branch electrofusion fitting comprises a housing comprising three ends arranged to respectively connect to the three pipe sections, and comprises three electrofusion branches, the three electrofusion branches respectively connected to the three ends and comprising a locking system, an inner bush and an outer bush wherein the inner bush comprises resistance wires and thermoplastic material, the locking system arranged to mechanically secure the outer bush to the inner bush, and the resistance wires can be connected to an electric power source for melting a surface of the inner bush to a pipe surface. This provides a tight fitting between the pipes and the multiple branch electrofusion fitting that can absorb forces created by the liquid in several directions.

[005] According to an embodiment, the inner bush comprises an inner pattern and the outer bush comprises an outer pattern which mesh with the inner pattern of the inner bush thereby forming the locking system. Such a locking system provides better mutual adhesion between the outer bush and the inner. The outer pattern and the inner pattern may have complementary matching shapes.

P62003207NL 2

[006] The inner and the outer pattern comprise a meshing and an interlocking shape, wherein the meshing and the interlocking shapes are complementary shapes meaning that the meshing shape is the same as the interlocking shape but mirrored such that both shapes complement each other and when placed one next to the other, the meshing shape connects with the interlocking shape thereby providing mutual adhesion between the outer and the inner bush.

[007] As said, the mechanical interlocking system may be formed by any inner and outer pattern with complementary shapes that can go from elliptical shape to dedicated shaped teeth, and anything in between. This allows that forces are transferred effectively over a certain length/area.

[008] According to an embodiment, the inner and the outer pattern comprise a wave shape. The wave shape provides an even better mutual adhesion between the outer bush and the inner. The wave shape also allows that the forces exerted by the fluid circulating through the multiple branch electrofusion fitting can be equally distributed through the inner and outer bush. The upper top surface has the form of a continuous wave-shape. In the context of the present disclosure the term "wave-shape" may be defined by any shape or configuration of the upper top surface having the form of a wave along the length extension when seen in a side view. In other words, the upper top surface may have the form of a longitudinal wave. In the context of the present disclosure the term "continuous wave-shape" means that the wave-shaped configuration of the upper top surface is formed substantially homogeneously, i.e. substantially without any steps, interruptions or platforms. For example, the wave may have a substantially sine-wave shaped configuration. In other words a "wave trough" and a "wave crest" may be formed. The wave-shaped formation of the upper top surface may increase the contact area between the inner and outer bush, and may facilitate connection more effectively.

Each wave shape has a longitudinal axis extending along the length extension, and a cross-sectional area extending in a plane that is substantially perpendicular to the longitudinal axis. It may have a topography which is chamfered, concave or convex to contribute to the overall continuous wave- shape configuration. The undulated shape formed by a continuous series of smooth protrusions and recesses that includes a first undulation comprising a first protrusion peak, a first recess bottom, a second recess bottom, a convex surface extending continuously between the first protrusion peak and the first recesses bottom, and a concave surface extending continuously between the first protrusion peak and the second recesses bottom. The inner pattern may comprise a number of waves.

[009] In an embodiment, one of the three ends may comprise an annular recess on an inner surface of the housing and configured to receive a sealing ring to fit around the corresponding pipe section.

This provides a leak tight connection of the pipes and the multibranch fitting.

[010] Each of the three electrofusion branches may be respectively connected to the thermoplastic material of one of the ends of the housing by welding means. The three electrofusion branches may be arranged in a T configuration. In another embodiment the three electrofusion branches may be arranged in a Y configuration. However, the three electrofusion branches may have any suitable configuration.

P62003207NL 3

[011] In an embodiment, the resistance wires are made of copper. Alternatively, the resistance wires may be made of iron or aluminium. Materials such as copper, iron or aluminium have a high heating resistance when an electrical current passes through them. Consequently, resistance wires made of copper, iron or aluminium provide low temperature materials enabling a reliable welding. Furthermore, such materials are relatively cheap, thereby reducing overall material costs.

[012] In a further embodiment, the thermoplastic material of the inner bush is polyolefin, preferable polyethylene (PE). Polyolefin material has a good weldability, and is easy to be welded. The thermoplastic material of the inner bush may be made of another polyolefin such as polypropylene (PP).

[013] According to an embodiment, the outer bush is made of a fiber-reinforced material. Fiber- reinforced materials are based on fibers embedded in a thermosetting material. Optionally, the fibers can be glass fibers, carbon fibers or aramid fibers. Optionally, the thermosetting material can be polyester, vinyl ester or epoxy resin. Fiber-reinforced materials offer not only a high strength to weight ratio, but also have exceptional properties such as high durability, stiffness, damping property, flexural strength and resistance to corrosion, wear, impact, and fire.

[014] According to a second aspect, an assembly comprising a multiple branch electrofusion fitting and three pipe sections is provided. Each pipe section comprises an inner casing made of thermoplastic material and a reinforced outer casing, wherein the three pipe sections are connected to each other by means of the multiple branch electrofusion fitting, preferably wherein each pipe is a high-pressure pipe.

An assembly with such an arrangement provides a strong permanent joining.

[015] In an embodiment, the reinforcement layer of each pipe section comprises fibers of at least one of glass fibers, carbon fibers or aramid fibers, embedded in a thermoplastic material.

[016] In another embodiment, the assembly may be fully non-metallic.

[017] According to an embodiment, the inner casings of each pipe section are welded to each other directly or by means of a sealing ring at corresponding ends facing each other. By this arrangement, pipe sections are connected to each other in a fluid tight manner, avoiding fluid reaching the resistance wires and leaking out of the fitting

[018] According to a third aspect, a method of manufacturing a multiple branch electrofusion fitting is provided. The method comprising the steps of: providing a housing comprising three ends arranged to respectively connect to three pipe sections; providing three electrofusion branches, each comprising a locking system, an inner bush comprising resistance wires and thermoplastic material, and an outer bush wherein the locking system is arranged to mechanically secure the outer bush to the inner bush, wherein the resistance wires can be connected to an electric power source for melting a first surface of the inner bush facing an external surface of a pipe section; and connecting the three electrofusion

P62003207NL 4 branches respectively to the three ends. This is an efficient way of manufacturing a multiple branch electrofusion fitting that ensures a tight mechanical connection for three pipes.

[019] The housing comprises three ends arranged to respectively connect to three pipe sections comprises forming a housing comprising three ends arranged to respectively connect to three pipe sections, preferably through injection molding and/or welding.

[020] According to an embodiment, the inner and for outer bush are made using injection molding.

This method has the advantages of being a simple manufacturing process, with high stability and low process cost, which overcomes shortcomings of prior art steel plate reinforced and fiber reinforced electrofusion fittings.

[021] According to a fourth aspect, a method of providing an assembly comprising a multibranch electrofusion fitting and three pipe sections is provided. The method comprises the steps of placing a multiple branch electrofusion fitting between corresponding ends of each pipe section; meshing the inner teeth with the outer teeth; and welding a surface of the inner bush of the multiple branch electrofusion to a corresponding external surface of each pipe section facing the inner bush.

[022] According to an embodiment, the method further comprises the step of inserting each pipe section in a corresponding end of the multiple branch electrofusion fitting and sealing an inner casing of each pipe section to the corresponding end of the multiple branch electrofusion fitting.

[023] According to an embodiment, the sealing step further comprises providing a sealing ring within an annular recess located on an inner surface of the housing wherein the sealing ring is fit around the corresponding pipe section, and/or welding the inner casing to three electrofusion branches are respectively connected to the corresponding end of the multiple branch electrofusion fitting.

BRIEF DESCRIPTION OF THE DRAWINGS

[024] The invention will be described further with respect to embodiments shown in the drawings.

[025] FIG. 1 shows a cross section of a multiple branch electrofusion fitting connected to three pipes.

[026] FIG. 2 shows an augmented view of a part of the multiple branch electrofusion fitting shown in

Fig. 1.

[027] FIG. 3 shows a flowchart illustrating a method for providing an assembly comprising a multiple branch electrofusion fitting and three pipe sections.

DESCRIPTION

[028] The following is a description of certain embodiments of the invention, given by way of example only and with reference to the figures. It is also to be understood that the terminology used herein is for

P62003207NL 5 the purpose of describing particular aspects only and is not intended to be limiting. In the context of the present application, at least one of A and B means any of only A, only B or a combination of A and B.

In the context of the present application, “fluid” means any liquid, gas, or other material capable of flowing when an external force or shear stress is applied.

[029] FIG. 1 shows a cross section of a multiple branch electrofusion fitting 1 connected to three pipe sections 9,10,21 and FIG. 2 shows a augmented view of a part of the multiple branch electrofusion fitting 1 and one of the pipe sections shown in Fig. 1. The multiple branch electrofusion fitting 1 as shown in FIG. 1 comprises a housing 202. The housing 202 comprises three open ends arranged to respectively receive and connect three pipe sections. The housing 202 shown in FIG. 1 has a T-shape.

But it should be understood that the housing may have any other suitable form for connecting three pipe sections at its three ends .

[030] The housing 202 comprises three electrofusion branches 210 respectively connected to the three ends and comprising an inner bush 2 and an outer bush 3. The inner bush 2 comprises resistance wires 4 and thermoplastic material. The inner bush 2 and the outer bush 3 comprise mechanical locking systems 5,6 that mesh with each other in order to transmit axial and/or tangential forces. A number of resistance wires 4 are accommodated on the internal surface of the inner bush 2, which resistance wires can be connected to an electric power source by way of connecting terminals (not shown). As said, the resistance wires 4 can be connected to an electric power source for melting a surface of the inner bush 2 facing an external surface of each pipe section to create a welded joint housing an inner bush 2 made of thermoplastic material, such as a polyolefin, and an outer bush 3 made of a fiber- reinforced thermosetting material for bearing axial forces. The resistance wires 4 are made of any suitable resistance wire material, suitable for heating due its electrical resistivity. For example, suitable resistance wire materials are copper, iron and aluminium.

[031] The outer surface of the inner bush 2 bears an inner pattern with an interlocking shape 6 running in the circumferential direction, while the inner surface of the outer bush 3 bears corresponding or complementary outer pattern with opposite meshing shape 5. These patterns 5,8, possibly a wave shape, mesh closely with each other, in such a way that the loads exerted on the inner bush 2, particularly those in the axial direction, are transmitted reliably to the outer bush 3. However, the inner bush 2 and the outer bush 3 may comprise any other messing pattern that provides a suitable locking system.

[032] The multiple branch electrofusion fitting 1 also comprises at its three ends two annular recesses 220 on the inner surface of the housing of the multiple branch electrofusion fitting 1. The two annular recesses 220 are shown in Fig. 1 with two sealing rings fitting inside the recesses 220. The two sealing rings also fit around the corresponding pipe section. The sealing rings may be made of natural rubber. Furthermore, the sealing rings may be made of a synthetic rubber, like Nitril, Silicone, fluoroelastomer …. or any suitable material.

P62003207NL 6

[033] The pipe sections 9,10,21 each include a liner 11 of a thermoplastic material, for example of the same material — such as polyolefin — as the inner bush 2 of the multiple branch electrofusion fitting.

The pipe sections 9,10,21 also have a reinforcement layer 12, which is composed of a reinforcement fiber layer, with for example, glass fibers, carbon fibers, or aramid fibers incorporated in a thermoplastic matrix. This reinforcement layer comprises helically wound tapas which each comprise threads or fibers which are juxtaposed, when sean in circumferential direction of the pipe. Optionally, the thermoplastic matrix of the reinforcement layer 12 can be the same material as the inner bush 2 of the multiple branch electrofusion fitting. The pipe sections 9,10,21 also have a cover layer 13 of thermoplastic material, for example of the same material as the inner bush 2 of the multiple branch electrofusion fitting.

[034] For the formation of the assembly comprising the multiple branch electrofusion fitting 1 and the three pipe sections 9,10,21 the thermoplastic material of both the inner bush 2 of the multiple branch electrofusion fitting 1 and the outermost layer 13 of thermoplastic material of the pipe sections 9,10,21 is melted, so that a connection is obtained. After cooling down, the assembly is complete.

[035] The axial tensile forces, which can be considerable in the case of high-pressure pipes, are transmitted by the way of the thermoplastic layer and the meshing and interlocking pattern of the inner bush 2 to the outer bush 3 of fiber reinforced material. Thus, a reliable and sufficiently strong assembly connecting pipe sections is ensured as a result. Furthermore, the sealing rings located inside of the annular recesses 220 provide a better connection between the pipes and the muitiple branch electrofusion fitting as the sealing rings fit around the corresponding pipe section.

[036] FIG. 2 shows in detail the connection between the pipe and the multiple branch electrofusion fitting. As shown in Fig. 2, the liner 11 of a pipe section may extend in a longitudinal direction further than the reinforcement layer 12 and the cover layer 13 such that part of the liner 11 abuts thereby. The part of the liner 11 that extends from the reinforcement layer 12 and the cover layer 13 overlaps with the part of the outer bush 3 that comprises the recesses 220. In this way, the sealing rings, when placed on the recesses 220, will fit around the liner 11 of the corresponding pipe section holding the section pipe in position with respect to the multiple branch electrofusion fitting 1 and providing a leak tight connection. As also shown in FIGS. 1 and 2, the inner bush 2 and the outer bush 3 may have a part comprising a mesh pattern and a part without the mesh pattern.

[037] The multibranch electrofusion fit 1 shown in FIGS. 1 and 2 may further comprise a support ring 230 made of polyamide material (PA) or any other suitable polymer.

[038] FIG. 3 shows a flowchart illustrating a method of manufacturing a multiple branch electrofusion fitting. The manufacturing method 30 comprises, at step 32, proving an inner bush 2 made of thermoplastic material, in which inner bush 2 resistance wires 4 are accommodated. The resistance wires 4 can be connected to an electric power source for melting a surface of the inner bush 2 facing

P62003207NL 7 an external surface of each pipe section 9,10,21 in order to create a welded joint. The inner bush 2 can be the inner bush of FIG. 1 and 2.

[039] The inner bush 2 can be formed by a core in which the resistance wires 4 are wrapped (e.g. helically) and afterwards a thermoplastic material is placed around the wires and core.

[040] At step 34, an outer bush 3 made of a fiber-reinforced thermosetting material is provided around the inner bush 2. The inner surface of the outer bush 3 bears mechanical locking system 5 running in the circumferential direction. Optionally, the outer bush 3 is made using molding or injection molding.

[041] FIG. 4 shows a flowchart illustrating a method for providing an assembly comprising a multiple branch electrofusion fitting 1 and three pipe sections 9,10,21.

[042] The method 40 for providing the assembly starts at step 42 by placing the multiple branch electrofusion fitting 1 between corresponding ends of each pipe section 9,10,21. The multiple branch electrofusion fitting 1 can be the multiple branch electrofusion fitting of FIG. 1 or FIG. 2 or any other multiple branch electrofusion fitting according to the present disclosure. Each pipe section 9,10, 21 can be introduced in corresponding ends of the multiple branch electrofusion fitting 1.

[043] At step 44 of the method 40, a surface of the inner bush of the multiple branch electrofusion is welded to a corresponding external surface of each pipe section facing the inner bush. When an electrical current is provided to the resistance wires 4 of the inner bush 2, the resistance wires increase their temperature, melting the thermoplastic material of their surroundings and an external surface of each pipe section, which create a welding joint when cooled. Electrofusion welding results in a very strong weld joint that is reliable and durable. This is due to the fact that the weld joint is heated very evenly, which prevents weak spots from forming.

[044] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CONCLUSIONS

1. A multi-branch electrical fusion fitting (1) for connecting three pipe sections (9,10,21), the multi-branch electrical fusion fitting comprising: — a housing (202) having three ends () arranged to connect respectively to the three pipe sections (9,10,21); and — three electrofusion branches (210), the three electrofusion branches connected to the three ends respectively and comprising an inner sleeve (2) and an outer sleeve (3), the inner sleeve (2) comprising resistance wires (4) and thermoplastic material, the inner sleeve (2) and the outer sleeve (3) comprising mechanical locking systems (5 ‚8) which engage each other to transmit axial and/or tangential forces, and the resistance wires (4) being connectable to an electrical power source for melting a surface of the inner sleeve (2) facing an external surface of each pipe section (13) to produce a welded joint.

2. The multi-branch electrical fusion fitting according to claim 1, wherein the inner sleeve comprises an inner pattern and the outer sleeve (3) comprises an outer pattern that engages with the inner pattern of the inner sleeve (2) to form the locking system.

3. The multi-branch electrical fusion fitting according to claim 2, wherein the inner and outer patterns comprise an interlocking and interlocking shape, the interlocking and interlocking shape being complementary shapes.

4. The multi-branch electrical fusion fitting of any preceding claim wherein one of the three ends includes an annular recess (220) on an interior surface of the housing and is configured to receive a sealing ring that fits around the corresponding pipe section.

5. The multi-branch electrical fusion fitting according to any one of the preceding claims, wherein each of the three electrical fusion branches is respectively connected by welding to the thermoplastic material of one of the ends of the housing.

6. The multi-branch electrofusion fitting according to any one of the preceding claims, wherein the three electrofusion branches are arranged in a T-configuration.

7. The multi-branch electrofusion fitting according to any one of the preceding claims, wherein the three electrofusion branches are arranged in a Y-configuration.

8. The multi-branch electrical fuse fitting according to any one of the preceding claims, wherein the resistance wires are made of copper.

9. The multi-branch electrofusion fitting according to any one of the preceding claims, wherein the thermoplastic material of the inner sleeve is polyolefin, preferably polyethylene (PE).

10. The multi-branch electrical fusion fitting according to any one of the preceding claims, wherein the outer sleeve is of fiber-reinforced material.

11. The multi-branch electrical fusion fitting of claim 10, wherein the fiber reinforced material comprises glass fibers, carbon fibers or aramid fibers.

12. The multi-branch electrical fusion fitting according to claim 10 or 11, wherein the fiber reinforced material comprises a thermosetting material, such as polyester, vinyl ester or epoxy resin.

13. An assembly comprising a multi-branch electrofusion fitting according to any preceding claim and three pipe sections, each pipe section comprising an inner sheath comprising thermoplastic material and a reinforcing outer layer, the stem assembly further comprising a welded joint between the multi-branch electrofusion fitting (1) and each pipe section (9,10,21).

14. The assembly of claim 13, wherein the reinforcement layer of each pipe section (12) comprises fibers of at least one of glass fibers, carbon fibers or aramid fibers embedded in thermoplastic material.

15. The assembly of any one of claims 12 to 13, wherein the assembly is made entirely of non-metal.

18. A method of manufacturing a multi-branch electrofusion joint, the method comprising the steps of: — providing a housing comprising three ends arranged to connect respectively to three pipe sections; — providing three electrofusion branches, each comprising a locking system, an inner sleeve comprising resistance wires and thermoplastic material, and an outer sleeve, the locking system being arranged to mechanically secure the outer sleeve to the inner sleeve, the resistance wires being connectable to an electrical power source for melting a first surface of the inner sleeve facing an external surface of a pipe section; and — connecting the three electrofusion branches to the three ends respectively.

17. The method of claim 18, wherein the step of providing a housing (202) comprising three ends arranged to respectively connect to three pipe sections, preferably by injection molding and/or welding.

18. A method of providing an assembly according to any one of claims 13 to 15, the method comprising the steps of: - inserting each pipe section into a corresponding end of the multi-branch electrofusion fitting according to any one of claims 1 to 12; and - sealing an inner jacket of each pipe section to the corresponding end of the multi-branch electrofusion fitting.

19. The method of claim 18, wherein the sealing step further comprises providing a sealing ring in an annular recess on an inner surface of the housing in which the sealing ring is disposed about the respective pipe section, and/or welding the inner jacket to three electrofusion branches respectively connected to the corresponding end of the multi-branch electrofusion fitting. -0-0-0-0-0-