COATED PIPE AND COMPOSITE PIPE

Description

[0001] The invention relates, on the one hand, to a metal pipe with a thermoplastic outer surface and a fiber-reinforced thermoset sheath enclosing the thermoplastic outer surface. Another aspect is a pipe assembly comprising several pipes with thermoplastic outer surfaces.

[0002] It is known to provide underground steel pipes for the transport of liquid or gaseous media with a relatively thin plastic coating, preferably made of polypropylene, polyethylene, fusion-bonded epoxy (FBE), or polyurethane, in order to prevent corrosion of the metallic pipe material, for example. Such layers of polypropylene, polyethylene, or polyurethane provide excellent corrosion protection, as soil moisture cannot come into contact with the metallic pipe material. However, they have the disadvantage of having relatively low mechanical strength. To protect the polypropylene, polyethylene, or polyurethane coating from undesirable mechanical abrasion, it is known to additionally coat the pipe with a fiber cement casing.However, the mechanical protective effect of the fiber cement is relatively low, since the fiber cement itself has only low inherent strength and, moreover, adheres poorly to the plastic layer due to the low adhesion properties of polypropylene, polyethylene, FBE or polyurethane.

[0003] For this reason, in essentially trenchless pipe-laying methods, such as horizontal drilling, mechanical damage to the thin and relatively soft polypropylene, polyethylene, or polyurethane layer often occurs during pipe jacking using a so-called culvert, so that the corrosion protection of the metallic pipe material is locally eliminated or at least unacceptably limited. In this context, the applicant has described a metal pipe with a thermoset coating in WO 01 / 05580 A1.

[0004] In another area, namely pipes for offshore oil production surrounded by seawater, which are intended to withstand high internal pressure, it is known to provide pipes on the outside with strips or wires made of glass, carbon or aramid fibres, which can also run at an angle to the longitudinal axis of the pipe, see US 2013 / 0146172 A1.

[0005] The object of the invention is to improve known methods in both open and trenchless construction for the coating of pipes and pipe connections.

[0006] According to the invention, this object is achieved by a metal pipe according to claim 1. The metal pipe has a thermoplastic outer surface or a sheath made of fusion-bonded epoxy (FBE) and a glass fiber-reinforced thermoset sheath enclosing the thermoplastic outer surface or the sheath made of fusion-bonded epoxy (FBE). The thermoset sheath is formed from several layers of glass fiber-reinforced plastic (GRP), wherein the layers of glass fiber-reinforced plastic are formed using glass fibers in the form of rovings, UD fabric, UD scrim, glass fiber mat, or glass fiber fabric, or a combination thereof, and the layers are applied to the thermoplastic outer surface using a wet-on-wet process using a vinyl ester, polyester, or epoxy resin. According to the invention, at least the outer layer of the thermoset sheath is formed from cross-wound textile glass rovings or glass fiber mats or glass fiber fabrics, or a combination of these glasses.Cross-wound means that the glass fibers are applied to the tube by winding, with one (glass) layer being applied with a first winding direction and a second (glass) layer being applied with a winding direction opposite to this winding direction, whereby the two glass layers do not cross or intersect each other.

[0007] According to the invention, at least the outermost layer of the thermoset coating – referred to here as the outer layer – is cross-wound. Such an outer layer offers the advantage that the pipe coated with the thermoset coating can be driven in any direction. With conventional pipes, there is typically one direction in which there is a greater risk of damage to the thermoset coating than in the opposite direction.

[0008] The glass fibers wound onto the tube are preferably in the form of rovings, in particular wound rovings, UD fabrics, or UD scrims. UD fabrics are glass fiber fabrics that are essentially formed from unidirectionally (UD) arranged glass fiber rovings that have relatively few fibers running perpendicular to the rovings. UD scrims are formed from unidirectionally (UD) arranged glass fiber rovings that are held together by holding threads running perpendicular to the rovings.

[0009] The thermoplastic sheathing surface is preferably applied directly to the metal pipe. The metal pipe is preferably a steel pipe.

[0010] Furthermore, it is preferred if the thermoset coating has an almost continuously decreasing thickness at the longitudinal ends of the pipe over a length of approximately 100 mm to a maximum of half a meter, with the thermoset coating being provided with a peel-off fabric on its outer surface in the area of decreasing thickness. This measure helps prevent the longitudinal ends of the pipes from having to be sanded prior to application of the on-site thermoset coating.

[0011] Furthermore, it is preferred if the layers of the fiber-reinforced thermoset sheathing formed by glass fiber mats or glass fiber fabric—with the exception of the exterior coatings—are formed by glass fiber webs wound around the pipe in such a way that the edges of each glass fiber web overlap by 2 to 5 cm. This ensures that each layer of the thermoset sheathing is constructed seamlessly and is self-contained.

[0012] According to a particularly preferred embodiment, the thermoset sheathing has one or two inner layers, each formed from a glass fiber mat or glass fiber fabric with a grammage between 300 and 500 g / m2, preferably approximately 450 g / m2. The inner layer or inner layers refer to those layers of the thermoset sheathing that are closest to the thermoplastic sheathing surface.

[0013] Particularly preferred are alternating layers of wound rovings and axial glass fibers, especially UD fabrics or UD scrims, i.e., layers of wound rovings and axial glass fibers are applied alternately. The required proportions of reactive resin relative to glass fibers can vary depending on the requirements. Preferably, approximately 600 g / m² of wound roving is used as reinforcement in the radial direction, and approximately 400 g / m² is used alternately in the axial tube direction. The use of chopped glass fibers (chopped roving) or solid fillers such as quartz sand between the individual glass layers is also possible. This reduces raw material costs and hardly affects the mechanical properties.

[0014] According to a further advantageous embodiment, several individual locally limited thermoset sheaths in the form of frames or skids are provided, which serve as spacers to a cladding tube during installation of the pipe and thus offer protection of the thermoplastic sheath surface against mechanical stress.

[0015] Also preferred are combinations of a thermoset sheath extending over the length of a pipe and shorter frames or skids.

[0016] The inner layer or layers are preferably formed from wound fiberglass sheets with a width of less than 35 cm. For example, if the fiberglass sheet is 30 cm wide and is wound around the pipe with an overlap of 3 cm, the resulting winding will have a pitch of 27 cm.

[0017] Furthermore, it is preferred if the thermoset sheath has at least one middle layer or two middle layers, each formed from a glass fiber mat or glass fiber fabric with a grammage (area weight) between 800 g / m 2 and 1200 g / m 2 , preferably with a grammage of approximately 1000 g / m 2 , e.g., 1030 g / m 2 . The middle layer or layers of the thermoset sheath are located in the radial direction of the pipe between the at least one inner layer and the outer layer.

[0018] The at least one middle layer of the thermoset sheath is preferably formed by a wound fiberglass web with a maximum width of 40 cm. With an overlap of approximately 5 cm, this results in a pitch of 35 cm per winding.

[0019] The thermoplastic outer surface of the pipe is preferably made of polyethylene, polypropylene or polyurethane, with polyethylene being the most preferred material.

[0020] Furthermore, it is preferred that the individual laminate layers are also constructed alternately from endless radial wound roving and a unidirectional textile glass fabric.

[0021] The pipe preferably has a nominal diameter between 100 and 2,500 mm and the thickness of the thermoset coating is preferably between 3 and 8 mm, particularly preferably about 5 mm.

[0022] A further aspect of the invention is a pipe assembly formed from several pipes of the aforementioned type, in which, for example, two to six pipes are connected parallel to one another with sleeves made of glass fiber reinforced plastic. The advantage of such a pipe assembly is that several pipes can be laid or driven simultaneously, with the sleeves made of glass fiber reinforced plastic being intimately bonded to the thermoset sheathing of the pipes, thus ensuring stability of the pipe assembly.

[0023] The required sleeve width and the sleeve spacing in the longitudinal direction depend on the project-specific static calculations.

[0024] Preferably, the sleeves are spaced approximately 2 to 4 m apart along the length of the pipe assembly. The width of each sleeve is preferably between 20 and 50 cm, for example, approximately 40 cm.

[0025] A pipe assembly is preferably formed from 2 to 5 and particularly preferably from 3 to 4 pipes.

[0026] The centerlines of the pipes in the area of the collars are preferably spaced apart by a distance greater than the outer diameter of the pipes. This means that the pipes in the pipe assembly are not directly adjacent to each other, but rather are spaced apart laterally. This makes it easier to install the pipe assembly even along slightly curved sections.

[0027] The sleeves, made of glass-fiber-reinforced plastic, are preferably adhesively bonded to the pipes. In this context, it is particularly advantageous if the sleeves have a resin matrix made of the same thermoset as the thermoset coating of the pipes, for example, vinyl ester, polyester, or epoxy resin.

[0028] A further aspect of the invention relates to pipe connections that are made on-site, i.e., during pipe laying, and which must also be coated after the weld has been created. As a corrosion protection layer, it is preferred to spray a polyurethane layer over the entire weld area, extending beyond the factory-applied corrosion protection layer. After this layer has cured, the surface is roughened, preferably by sandblasting, and a glass fiber-reinforced thermoset coating is applied. This thermoset coating is formed from several layers of glass fiber mat or glass fiber fabric, or a combination of both, with the layers being applied to the polyurethane surface using a wet-on-wet process with a vinyl ester, polyester, or epoxy resin. The thickness of this on-site thermoset coating is preferably between 3 and 8 mm, particularly preferably approximately 5 mm.

[0029] Further features and properties, as well as variants of pipes and pipe bundles according to the invention, can be found in the following description of exemplary embodiments. The invention is thus explained in more detail using the following exemplary embodiments. The figures illustrating the exemplary embodiments show the following: Fig. 1: is a partial longitudinal section through a pipe with a thermoplastic jacket surface and a fiber-reinforced thermoset coating enclosing it; Fig. 2: shows an example of a cross-section through a pipe coated according to the invention; and Fig. 3: shows a longitudinal end of a pipe with a thermoset coating with a thickness decreasing towards the longitudinal end; Fig. 4: shows a pipe assembly consisting of three pipes connected to one another by means of sleeves, in a partially sectioned end view; Fig. 5: shows the pipe assembly consisting of Figure 4in a side view; and Fig. 6: shows a longitudinal section through a pipe section with a pipe having a thermoplastic outer surface and a fiber-reinforced thermoset sheath enclosing the thermoplastic outer surface, as well as a sliding skid applied thereon as a spacer to a cladding pipe.

[0030] Fig. 1 is a partial longitudinal section through a pipe 100, which is formed by an initial pipe 105, for example made of metal, a thermoplastic jacket surface 150 applied thereto and a fiber-reinforced thermoset jacket 180 enclosing the thermoplastic jacket surface 150.

[0031] The illustrated outlet pipe 105 has a nominal diameter of 500 mm and is composed of several spiral-welded pipe sections 110 and 120 connected to one another by a weld seam 130.

[0032] A wall 140 of the pipe 100 is made of steel and carries a thermoplastic jacket surface 150 made of polyethylene (PE) serving as a corrosion protection layer.

[0033] In the area of the weld seam 130, the thermoplastic jacket surface 150 is interrupted and replaced by a shrink sleeve or a repair tape 170 made of polyethylene to bridge the interruption in the thermoplastic jacket surface 150. In order to weld the pipe sections 110 and 120 together, the thermoplastic jacket surface 150 is removed at the ends 115 and 125 of the pipe sections 110 and 120 before welding them together and replaced by the shrink sleeve or the repair tape 170 made of polyethylene after the welding process.

[0034] Figure 1 It can be seen that the thickness of the thermoplastic sheath surface 150 corresponds approximately to the thickness of the fiber-reinforced thermoset sheath 180 and is approximately 5 mm.

[0035] The thermoset sheath 180 has one or two inner layers 182 and one or two middle layers 184 as well as an outer layer 186.

[0036] Each of these layers is made of glass fiber reinforced plastic, namely textile glass fibers wound around the tube 100, which are embedded in a resin matrix made of vinyl ester resin, polyester resin or epoxy resin.

[0037] The fiber webs that form the inner layer 182 or the inner layers 182 as well as the fiber webs that form the middle layer 184 or the middle layers 184 are wound in the tube 100 in such a way that the two edges of each fiber web overlap by about two to five centimeters.

[0038] In the exemplary embodiment, the inner layer 182 or the inner layers 182 are formed from a glass fiber mat with a grammage of approximately 450 g / m2, while the middle layer 184 or the middle layers 184 are formed from a glass fiber mat with a grammage of approximately 1030 g / m2.

[0039] The outer layer 186, in contrast to the inner layer 182 or the inner layers 182 and the middle layer 184 or the middle layers 184, is not applied with a uniform winding direction for each layer, but is cross-wound, i.e. the outer layer is formed by two fiber webs that are wound with opposite winding directions and cross each other so that they are interwoven.

[0040] All layers 182, 184, and 186 are applied wet-on-wet to the thermoplastic shell surface 150, meaning that each subsequent layer is applied to the preceding layer before the resin forming the resin matrix of the preceding layer has cured. In this way, layers 182, 184, and 186 are intimately bonded to one another.

[0041] The glass content of the thermoset sheath 180 is at least 35 percent by mass, ie the resin content is less than 65 percent.

[0042] Figure 2 shows an example of a cross section through a pipe 100 coated according to the invention.

[0043] Figure 3shows a longitudinal end of a pipe 100 with a thermoset coating 180, the thickness of which decreases over a length L towards the longitudinal end of the pipe 100. The thermoset coating 180 is provided with peel ply 300 on its outside in its region L of decreasing thickness. Both measures - the decreasing thickness and the peel ply 300 - contribute to the fact that the longitudinal ends of the pipes 100 can be easily joined together by welding and that, after welding the pipes, a thermoset coating can be easily created in the area of the weld seam. The peel ply ensures that the original thermoset coating in the area of the pipe ends does not have to be sanded. The decreasing thickness of the original thermoset coating results in an almost continuous transition from the original thermoset coating to the local thermoset coating created in the area of the weld seam after welding the pipes.

[0044] Figure 4 shows a pipe assembly consisting of three pipes 100, which are connected to one another to form the pipe assembly 410 by means of sleeves 400 made of glass fiber reinforced plastic.

[0045] The pipes 100 are spaced apart from each other in the area of the sleeves 400, so that the pipes 100 of the pipe assembly 410 do not touch each other laterally and do not directly abut each other. This makes it easier to lay the pipe assembly 410 even along a slightly curved path. To ensure this spacing, spacers 420 are provided in the area of the sleeves 400, which keep the pipes 100 laterally spaced apart.

[0046] The sleeves 400, made of glass-fiber-reinforced plastic, are adhesively bonded to the pipes. The resin matrix of the sleeves is made of the same thermoset as the thermoset sheath 180 of the pipes 100, for example, vinyl ester or polyester resin.

[0047] The required sleeve width and the sleeve spacing in the longitudinal direction depend on the project-specific static calculations.

[0048] How Figure 5 As can be seen, the sleeves 400 are spaced apart from one another at a distance A of approximately 2 to 4 m in the longitudinal direction of the pipe assembly 410. The width B of each sleeve 400 is preferably approximately 40 cm.

[0049] Instead of three pipes (as shown), a pipe assembly can also be formed from two to six pipes, for example. The advantage of such a pipe assembly is that several pipes 100 can be laid or driven simultaneously, with the sleeves 400 made of glass fiber reinforced plastic being intimately connected to the thermoset sheath 180 of the pipes 100, ensuring stability of the pipe assembly.

[0050] Figure 6shows a longitudinal section through a pipe section with a pipe 100 with a thermoplastic outer surface 150 and a fiber-reinforced thermoset sheath 180 surrounding the thermoplastic outer surface 150, as well as a sliding skid 450 applied thereon as a spacer to a cladding pipe 500. The cladding pipe 500 serves here as external protection, into which the pipe 100, together with the thermoplastic outer surface 150, thermoset sheath 180, and sliding skids 450 applied thereon, are pushed. Preferably, several sliding skids 450 are provided with a longitudinal spacing from one another.

[0051] The sliding skids 450 represent a feature that can be implemented independently of a thermoset coating or in conjunction with any thermoset coating. List of reference symbols

[0052] 100Pipe 105Outlet metal pipe 110, 120Pipe section 115, 125Longitudinal end of a pipe 130Weld seam 140Wall 150Thermoplastic jacket surface 170Repair tape 180Thermoset coating 182Inner layer of thermoset coating 184Middle layer of thermoset coating 186Outer layer of thermoset coating 300Peel ply 400Cuff 410Pipe assembly 420Spacer 450Skid 500Sheathing pipe

Claims

1. Metal pipe (100) having a thermoplastic casing surface (150) or a coating of fusion-bonded epoxy (FBE) and a fibre-reinforced thermo-setting coating (180) that encloses the thermoplastic casing surface (150) or a coating of fusion-bonded epoxy (FBE) and that is formed from multiple layers of textile glass fibres that are applied to the thermoplastic casing surface (150) in a wet-on-wet process using a vinyl ester, polyester, or epoxy resin, characterized in that at least the outer layer of the thermosetting plastic coating (180) is formed by cross-wound textile glass rovings or glass fibre mats or glass fibre fabrics or a combination of these textile glass fibres, at least the outer layer (186) being formed by two glass fibre webs which are wound with opposite winding directions, in that a first glass fibre web is applied with a first winding direction and a second glass fibre web is applied with a winding direction opposite to this winding direction.

2. Metal pipe (100) according to claim 1, characterized in that the thermoplastic casing surface (150) is applied to a steel pipe (100).

3. Metal pipe (100) according to claim 1 or 2, characterized in that the thermo-setting coating (180) is provided with peel ply (300) on its outer side over a length of approximately 100 mm up to half a metre, the thermosetting plastic sheathing being provided with peel ply (300) on its outer side in its portion of decreasing thickness at the longitudinal ends of the metal pipe (100).

4. Metal pipe (100) according to at least one of claims 1 to 3, characterized in that the layers of the fibre-reinforced thermo-setting coating (180) formed by glass fibre mats or fabrics, with the exception of the outer layer (186), are formed by glass fibre webs which are wound around the metal pipe (100) in such a way that the edges of the respective glass fibre web overlap by two to five centimetres.

5. Metal pipe (100) according to at least one of claims 1 to 4, characterized in that the layers of the fibre-reinforced thermo-setting coating (180) formed by glass fibre mats or fabrics having one inner layer (182) or two inner layers (182) each formed by a glass fibre mat or fabric with a grammage between 300 and 500 g / m2, preferably of about 450 g / m2.

6. Metal pipe (100) according to claim 5, characterized in that the inner layer (182) or layers (182) are formed by wound fiberglass webs having a width of less than 35 centimetres.

7. Metal pipe (100) according to at least one of claims 1 to 6, characterized in that the layers of the fibre-reinforced thermo-setting coating (180) formed by glass fibre mats or fabrics having one middle layer (184) or two middle layers (184), are each formed by a glass fibre mat or fabric with a grammage of between 800 and 1200 g / m2, preferably of about 1000 g / m2, the middle layer (184) or layers (184) being located between, in the radial direction of the metal pipe (100), at least one inner layer (182) and the outer layer (186) of the fibre-reinforced thermo-setting coating (180).

8. Metal pipe (100) according to claim 7, characterized in that the middle layer (184) or the middle layers (184) are formed by wound glass fibre webs with a maximum width of 40 cm.

9. Metal pipe (100) according to at least one of claims 1 to 8, characterized in that the thermoplastic casing surface (150) is formed by polyethylene, polypropylene, fusion-bonded epoxy (FBE) or polyurethane.

10. Metal pipe (100) according to at least one of claims 1 to 9, characterized in that the metal pipe (100) has a nominal diameter between 100 and 2,500 millimetres and that the thickness of the thermo-setting coating (180) is between two and eight millimetres, preferably about five millimetres.

11. Metal pipe (100) according to at least one of claims 1 to 10, characterized in that cross-wound fibre webs of the outer layer (186) cross each other in such a way that they are interwoven as a result.

12. Metal pipe (100) according to at least one of claims 1 to 10, characterized in that cross-wound fibre webs of the outer layer (186) do not cross each other.

13. Pipe combination (410) having a plurality of pipes (100) according to at least one of claims 1 to 9, characterized in that pipes (100) are connected parallel to one another with sleeves (400) of glass fibre reinforced plastic.

14. Pipe combination (410) according to claim 13, characterized in that the centre lines of the pipes (100) in the area of the sleeves (400) have a distance from one another which is greater than the outer diameter of the pipes (100).

15. Pipe combination (410) according to claims 13 or 14, characterized in that sleeves (400) are adhesively connected to the pipes (100).