Non-permeable pipe

Abstract

A hollow pipe (10) includes a first layer (12), and a non-permeable aluminum layer (18) formed of a helically wound strip of aluminum. Such a first layer (12) could be an inner line, for example, made of high-density polyethylene pipe and / or nylon. The aluminum layer (18) is be made non-permeable by overlapping the strip in the winding and laser welding the layers together in the overlap area.

Description

[0001] NON-PERMEABLE PIPE

[0002] FIELD OF THE INVENTION

[0003] This disclosure relates to a an elongated tube, in particularly an elongated tube formed by helically wound Aluminum strips.

[0004] BACKGROUND

[0005] Swage lining is a method of slip lining whereby the diameter of the pipe is temporarily reduced by swageing prior to insertion in the pipe. In this method of slip lining, a polymer lining is pulled through a steel pipe for rehabilitation and / or protection purposes.

[0006] Before installation, a high-density polyethylene pipe wrapped with aluminum (HDPE- Al pipe), slightly larger than the host pipe’s diameter, is selected. Upon installation, the HDPE-AI pipe is connected to a pulling rig and pulled through a reduction die slightly smaller than the host pipe. This temporarily reduces the size of the HDPE-AI pipe while a section, as long as 1.5 kilometers, is pulled through the host steel pipe. After installation, tension is released and the HDPE-AI pipe loses length as it reverts to the full diameter of the host Pipe.

[0007] To ensure a certain degree of bonding between the aluminum and the HDPE in the HDPE-AI pipe, a tie-layer is typically used. This tie-layer is an adhesive which bonds to the HDPE and the aluminum in the overlapping areas of the helical wind. However, some small amounts of gas, such as Methane, CO2 or Hydrogen, can still permeate such a layer, and therefore some gas is able to escape such a pipe. When the HDPE-AI pipe is inside the steel pipe for longer amounts of time, this leads to quite some buildup of gas between the steel pipe and the HDPE-AI pipe. In some cases, such a buildup can even cause a collapse of the HDPE-AI pipe when the pressure is let out of the HDPE-AI pipe.

[0008] Some prior art pipes, in an attempt to avoid such a collapse when the pressure is let out, use aluminum strips extending in the longitudinal direction around the liner, bending the aluminum strips along their lengths to fit around the inner HDPE layer. The aluminum strips are then longitudinally welded together (e.g., laser welding) to form a non-permeable layer around the HDPE liner. However, since the strips have to be longitudinally bent, this limits the length and size of pipe which could be formed, and typically the pipes have a maximum diameter of about 65 mm when formed in this way. Additionally, the tolerances for forming pipes with longitudinally extending aluminum strips is very difficult due to the multiple layers having to fit together so precisely over the length of the pipe. US 2016 / 362968 shows a liner having an outer surface coated with a fluid absorbing coating which is cladded to a tubing string by inserting the folded liner into the tubing string and then unfolding the liner against the tubing string. The liner may be a long single thin foil corrosion resistant liner coated with a sticky glue and a hygroscopic and / or other fluid absorbing coating to absorb fluid pockets trapped between the tubing and liner and inhibit corrosion and leakage of, the elongate tubing string.

[0009] EP 2810769 B1 shows a protective jacket tube with a diffusion barrier and a core tube made of a plastic and an extruded protective jacket. The diffusion barrier between the core tube and the protective sheath is formed as a multilayer composite film with at least one metal foil layer and / or at least one plastic film with diffusion-inhibiting properties between different plastic layers, for example, polyethylene, polypropylene, polypropylene copolymer, polyamide or other suitable thermoplastic.

[0010] EP 1258340 A2 shows a pipe with a barrier layer of metal foil between an inner core and an outer cover, each bonded to the barrier layer by a tie layer formed integrally with the core and cover. The tie layer of the core is activated by heating prior to applying the barrier layer and bonding may be enhanced by applying a thin layer of the tie layer material to the heat activated tie layer.

[0011] WO 2011 / 070353 A2 shows a method for restoring a degraded pipeline, the method comprising: removing a degraded part of an inner flow pipe of a pipeline leaving a space between two spaced-apart sections of the inner flow pipe; positioning a new pipe in the space; connecting the new pipe to the two spaced-apart sections of the inner flow pipe thereby re-establishing a flow channel through the inner flow pipe; the new pipe having a core pipe with a first strengthening wrap thereon, a second strengthening wrap around the first strengthening wrap, and a protective outer wrap on the second strengthening wrap.

[0012] WO 2021 / 084236 A1 shows a pipe liner and a method of lining a host pipe with such a pipe liner. The pipe liner comprises a barrier layer, which prevents permeation through the liner, surrounding an inner polymer pipe and optionally covered by an outer polymer pipe. The inner polymer pipe is porous which permits free movement of gas between the internal bore of a lined pipe and the barrier layer, so as to prevent accumulation of gases anywhere in the lined pipe, while ensuring that gases do not permeate to, and damage, the host pipe. The liner can be inserted using Swagelining, roll-down, or any other suitable close-fit lining techniques, without compromising the effectiveness of the barrier layer.

[0013] SUMMARY OF THE INVENTION

[0014] According to a first aspect, a hollow pipe comprises a first layer, and a non-permeable aluminum layer formed of a helically wound strip of aluminum. Such a pipe is able to be formed in a variety of diameters and lengths while ensuring non-permeability through using one or more helically wound overlapping strips of aluminum. Such pipes can be especially useful in processes where non-permeation is needed, for example, swage-lining.

[0015] The non-permeable aluminum layer is helically wound such that successive winds have an overlap area., and the overlap area is laser welded together during or shortly after the winding. Optionally, the laser welding is performed from an outside of the pipe and does not permeate the lower layer in the overlap area. Such laser welding in the overlap area is an effective method for ensuring that the aluminum strip forms a non-permeable layer without needing a lot of additional materials and / or manufacturing processes. The laser welding could be a stationary laser, with a moving pipe or a moving laser which rotates around the pipe as the strip is wrapped around the inner layer. By ensuring the laser does not permeate the lower layer of strip in the overlap area, the laser effectively welds the upper and lower strip layers together while ensuring there is no penetration through and thus no gas can flow from the inside to the outside of the layer or vice versa.

[0016] According to an embodiment, the pipe has a diameter in the range of 10 mm to 400 mm. By using a method of helically wrapping a strip and securing the helically wrapped strip such that it is non-permeable (e.g., through laser welding), the pipe is able to be formed in a larger range of diameters and / or lengths than prior art pipes. Thus, non-permeable pipes with diameters up to 400 mm or even larger can be formed.

[0017] According to an embodiment, the pipe further comprises an outer layer. Such an outer layer can form a protective layer around the non-permeable layer.

[0018] According to an embodiment, the first layer and / or the outer layer is high density polyethylene (“HDPE”) and / or nylon. Optionally, the first layer and / or outer layer is extruded. Such materials can form a stable but stretchable inner and / or outer layer around the non-permeable layer, which is especially useful in pipes which are used for swagelining. Extrusion can be a simple method of forming the first layer and / or outer layer in varying lengths and sizes of pipe.

[0019] According to an embodiment, the pipe further comprises an adhesive layer between the first layer and the non-permeable aluminum layer and / or between the non-permeable aluminum layer and the outer layer. Optionally, such adhesive layers can be extruded with the inner layer and / or extruded around the non-permeable aluminum layer. Such adhesive layers can help to ensure that adjacent layers of the pipe remain connected together, even through any stretching and / or increase or decrease in diameter (e.g., as the pipe is pulled, inflated, released, etc.).

[0020] According to an embodiment, the first layer and the outer layer are the same material. Forming the first layer and the outer layer of the same material can help ensure that they have the same reactions to any stretching and there is little to no separation of layers in the pipe even through stretching or other deformation of the pipe.

[0021] According to a further aspect, a method of forming a pipe comprises forming a first layer; helically wrapping an aluminum strip around the first layer such that successive winds have an overlap area; and laser welding successive winds together in the overlap area to form a non-permeable pipe. Such a method is able to form a non-permeable pipe of various lengths and diameters in a simple process. The winding of an aluminum strip to form overlap areas, and the use of laser welding ensure that the aluminum strip forms a layer which is non- permeable in the pipe, even for small molecule gases such as Methane, CO2 or Hydrogen.

[0022] According to an embodiment, the step of forming a first layer comprises extruding a high density polyethylene (HDPE) and / or nylon layer. Such extrusion of a first layer can be a simple way of forming the inner layer of pipe and providing a base around which to wrap the aluminum strip. HDPE and / or nylon can form a strong but flexible layer able to stretch as necessary for the use of the pipe (e.g., in a swage-lining process).

[0023] According to an embodiment, the step of laser welding successive winds together in the overlap area comprises lasering through an outer aluminum layer of the overlap area but not lasering fully through a lower layer. Such a method ensures that successive winds are connected together in a non-permeable manner, but that the laser does not penetrate the lower layer to ensure non-permeability.

[0024] According to an embodiment, the method further comprises extruding an outer layer over the aluminum layer. Optionally, the outer layer is HDPE and / or nylon. Such a layer can act as a protective layer over the non-permeable layer, and extrusion can be a simple and efficient method of forming.

[0025] According to an embodiment, the method further comprises forming one or more adhesive layers between the first layer and the aluminum layer and / or between the aluminum layer and the outer layer. Optionally, the adhesive layer(s) can be extruded or applied in any other suitable manner. Such adhesive layers can help to ensure the pipe layers remain connected, even through any deformation or stretching of the pipe.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will be described further with respect to embodiments shown in the drawings.

[0028] FIG. 1 shows a perspective view of a pipe being formed;

[0029] FIG. 2 shows a cross-sectional view of two overlapping helical layers of the pipe of FIG. 1 ; and FIG. 3 shows a cross-sectional view of a pipe.

[0030] DESCRIPTION

[0031] FIG. 1 shows a perspective view of a pipe 10 being formed, FIG. 2 shows a cross- sectional view of two overlapping helical layers pipe 10, and FIG. 3 shows a cross-sectional view of pipe 10. Pipe 10 includes inner layer 12, helically wrapped layer 14 and outer layer 16. Adhesive layers (not shown) can also be included between each of layers 12, 14 and 16.

[0032] Inner layer 12, can be a pipe liner, and can be, for example, High-density polyethylene (hereinafter “HDPE”), nylon or any other suitable liner material depending on the intended use for pipe 10. Inner layer 12 can be formed by extrusion, and in some embodiments, a layer of adhesive can be applied as layer 12 is extruded. Outer layer can also be formed of HDPE, propylene (“PP”) or nylon, and is also typically extruded.

[0033] After extruding inner layer 12 and application of adhesive layer, layer 14 is formed by helically winding strip 18 around inner layer 12 (with adhesive). Strip 18 can be formed of aluminum (including alloys), or any other suitable material which can be wrapped around inner layer 12 to form a non-permeable layer. When wrapping strip 18, successive windings overlap each other to form an overlap area 20 shown in Fig. 2. Overlap area can be, for example, 2%-20% of the width of strip 18, preferably 5-10%, though can vary depending on the material used for strip 18, the diameter of the pipe, etc. The winding can be, for example, 40 - 80 degrees, preferably 40- 55 degrees, more preferably around 45 degrees.

[0034] As strip 18 is being wrapped (or shortly thereafter), laser 22 is used to laser weld success layers of strip 18 in overlap area 20. Thus, laser 22 welds upper layer 18a to lower layer 18b, as shown in FIG. 2. This typically means that laser 22 is precisely configured to weld through upper layer 18a, and only partially through lower layer 18b such that successive wraps of strip 18 are welded together to form non-permeable layer 14. Such laser welding can be performed by laser 22 moving around pipe 10 with the wrapping of strip 18 or through pipe 10 itself rotating as it is formed. In some embodiments, two or more strips 18 are wrapped and laser welded together at the same time to form non-permeable layer 14. Such configurations would also involve multiple lasers for the welding in each overlap area. Next, a further layer of adhesive can be applied to non-permeable layer 14, and outer layer can be formed, for example, through extruding HDPE or nylon.

[0035] By forming pipe 10 with one or more helically wrapped and laser welded strip 18, pipe 10 is able to ensure that there is no flow of air or liquids from an inside of pipe 10 to outside or vice versa. Such a method can allow for forming of a pipe of many different lengths and / or diameters that is non-permeable. Thus, such a configuration helps to decrease or eliminate any flow of gases such as Methane, CO2 or Hydrogen from an inside to an outside of pipe 10 or vice-versa.

[0036] As mentioned in the background, in swage-lining, the HDPE-AI pipe can be inside the steel pipe for long periods of time (e.g., 6 months - 25 years), during which small amounts of gases could flow from inside the pipe to outside between the prior art HDPE-AI pipe and the steel pipe. This was from small amounts of gas being able to flow through the tie-layers or adhesive layers (which are holding successive Al wrap layers together). By instead using a method whereby strip 18 is helically wound and then laser welded together in an overlap area to form non-permeable layer 14, pipe 10 is able to ensure that that there is no flow from the inside of pipe 10 to the outside, even over longer periods of time. Additionally, pipe 10 is able to be made in many different lengths and sizes, for example, with diameters from 110 to 400 mm or more, as the helical winding process is flexible for both length and diameter (unlike the prior art bending and longitudinal welding processes). Thus, pipe 10 avoids collapse issues seen in prior art pipes used in swage-lining, and is able to be formed in a much larger range of diameters and / or lengths than prior art pipes formed from bending and welding longitudinal Al strips.

[0037] While pipe 10 is shown as round, it could be other shapes in other embodiments, for example, oval shaped or egg-shaped. Additionally, while Figs. 1-2 show one strip 18 being helically wound, multiple strips 18 could be helically wound at the same time, forming multiple overlap areas, each of which would be laser welded. Using multiple strips could result in a more efficient process of forming pipe 10.

[0038] 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

CLAIMS1 . A hollow pipe (10) comprising:- a first layer (12), and a non-permeable aluminum layer (14) formed of a helically wound strip of aluminum (18), wherein the non-permeable aluminum layer (18) is helically wound such that successive winds have an overlap area (20), and the overlap area (20) is laser welded together during or shortly after the winding.

2. The hollow pipe (10) of claim 1 , wherein the laser welding is performed from an outside of the pipe and does not permeate the lower layer in the overlap area (20).

3. The hollow pipe (10) of any of the preceding claims, wherein the pipe has a diameter in the range of 10 mm to 400 mm.

4. The hollow pipe (10) of any of the preceding claims, wherein the first layer (12) is high density polyethylene.

5. The hollow pipe (10) of any of the preceding claims, wherein the first layer (12) is extruded.

6. The hollow pipe (10) of any of the preceding claims, and further comprising an adhesive layer between the first layer and the non-permeable aluminum layer (14).

7. The hollow pipe (10) of any of the preceding claims, and further comprising an outer layer (16).

8. The hollow pipe (10) of claim 7, wherein the first layer (12) and the outer layer (16) are the same material.

9. A method of forming a pipe (10), the method comprising: forming a first layer (12); helically wrapping an aluminum layer (18) around the first layer such that successive winds have an overlap area (20); and laser welding successive winds together in the overlap area (20) to form a non- permeable pipe.

10. The method of claim 9, wherein the step of forming a first layer (12) comprises: extruding a high density polyethylene, propylene and / or nylon layer.

11. The method of any of claims 9-10, wherein the step of laser welding successive winds together in the overlap area comprises lasering through an outer aluminum layer of the overlap area (20) but not lasering fully through a lower layer.

12. The method of any of claims 9-11-, and further comprising extruding an outer layer over the aluminum layer (14).

13. The method of any of claims 9-12-, and further comprising applying one or more adhesive layers.

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