METHOD FOR PRODUCE A POLYMER-REFINED PIPELINE ELEMENT, AS WELL AS PIPELINE ELEMENT AND PIPELINE SYSTEM WITH THE SAME

Description

[0001] The present invention relates to a method for producing a polymer-modified pipe element. The invention further relates to a pipe element, in particular one produced by such a method. The invention also relates to a piping system comprising such a pipe element.

[0002] Methods for manufacturing pipelines for fire extinguishing systems are generally known. Pipeline elements in fire extinguishing systems face the particular challenge of being installed unused in buildings for very long periods of time, and in the event of an emergency, they must reliably perform their assigned task of fluid transport.

[0003] Fire extinguishing systems are widely used in which the piping systems carry extinguishing fluid even in standby mode, and alternatively, in which the sprinkler lines do not yet contain extinguishing fluid in standby mode. Particularly with the latter systems, the susceptibility to corrosion inside the pipes is a significant challenge, which is why efforts have been made in the prior art to reduce the corrosion resistance of piping components, especially for fire extinguishing systems. To circumvent the problem of corrosion within fire extinguishing systems, alternative approaches have been developed in which large parts of the piping system, and with them the majority of the installed piping components, are not filled with extinguishing fluid in standby mode, but with gases.

[0004] The costs for state-of-the-art systems are sometimes considerable, as on the one hand the use of corrosion-resistant pipes or elaborate passivation processes were necessary, and on the other hand high installation costs were required for filling the respective pipeline systems with gas.

[0005] EP 1 2153 964 and EP 2 766 653 each describe systems and processes that represent a significant improvement over the prior art. These documents describe, for the first time, the use of a polymer coating via autodeposition on the inside of pipes in fire extinguishing system piping components. The polymer coating described therein is extremely robust due to the ionic bonding of a polymer-based coating material to the pipe surface and allows the use of simple metals that are not inherently corrosion-resistant, particularly low-alloy steels. At the same time, very low corrosion development, even complete corrosion resistance, is achieved, even over extended observation periods.

[0006] EP 0 344 896 A1 further discloses a pipe element composed of several pipe sections and a method for its manufacture. The pipe sections are aligned end-to-end and joined by welding. Adhesive joints can be provided at predetermined intervals as expansion joints. A lining tube is arranged on the inside of the pipe element, which is brought into contact with the inside of the pipe by means of an adhesive applied to the lining tube.

[0007] Nevertheless, there is still room for improvement compared to the current state of the art. The aim is to not only provide simple piping elements with a polymer coating—elements consisting solely of a tubular hollow body with an inlet and an outlet—but also piping elements with multiple outlets, and especially those composed of several hollow bodies. The assembly of multiple hollow bodies into complex piping elements is achieved either by joining the hollow bodies using couplings, pipe connectors, and the like, or by welding. It has been found that the use of pipe connectors in the transition area between hollow bodies leads to an increase in flow resistance, which reduces the flow velocity and increases the resulting pressure losses, expressed as the so-called C-factor.This potentially increases the necessary equipment for pumping the extinguishing fluid, for example, by requiring more powerful pumps or larger pipe diameters. The C-factor is calculated according to generally known principles using the Hazen-Williams equation.

[0008] In the prior art, where the first and second hollow bodies of a pipe element were joined by welding, this was done solely with regard to the requirement of pressure tightness. In previous practice, the connections of the hollow bodies on the pipe element were indeed pressure-tight. However, the long-term corrosion resistance known, for example, from EP 2 766 653, was not reliably achieved.

[0009] Accordingly, the invention was based on the objective of providing a method for manufacturing a polymer-refined pipe element that overcomes the disadvantages described above as far as possible. In particular, the invention was based on the objective of providing a method of the type described above that ensures sufficient corrosion resistance in complex pipe elements despite the presence of a welded joint.

[0010] The invention solves the underlying problem in the method described above with the features of claim 1. In particular, the method comprises the steps: Providing a first hollow body and a second hollow body, wherein the first and second hollow bodies each have a wall, and the wall each has a circumferential edge surface, wherein the circumferential edge surface of the first hollow body is formed at an end face of the hollow body, and wherein the circumferential edge surface of the second hollow body is spaced apart from the end faces of the second hollow body and defines a cutout through the wall of the second hollow body, aligning the circumferential edge surface of the first hollow body and the circumferential edge surface of the second hollow body with each other, welding the first hollow body to the second hollow body along the circumferential edge surfaces, producing a circumferential weld seam having a root extending on the inside of the pipe element, and applying a polymer-based layer to the inside of the pipe element.the polymer-based layer completely covers the inside of the pipe element and the root of the weld.

[0011] The invention is based on the understanding that, by applying a weld seam that extends completely around the inside of the pipe element, i.e., in a circle, the weld root creates an advantageous surface geometry compared to the prior art. This geometry enables complete wetting of the entire inner surface of the pipe element, including a transition area from the first to the second hollow body, with the polymer-based protective layer. The fully circumferential weld root ensures a significantly smoother contour transition between the first and second hollow bodies compared to the prior art. This makes it possible, using polymer finishing, to render more complex pipe elements, rather than just single-piece pipe elements, corrosion-resistant in the long term.The smooth contour transition between the first and second hollow bodies offers advantages for all types of polymer finishing, but makes the pipe element particularly well-suited for polymer finishing via autodeposition, as the flow conditions inside the pipe are less disrupted due to the smooth contour transition. Aligning the edge surfaces means that the edge surface of the first hollow body and the edge surface of the second hollow body are oriented and spaced relative to each other in such a way that the two hollow bodies can be welded together along their edge surfaces.

[0012] The inventive method is advantageously further developed in that the edge surfaces of the first and second hollow bodies each have a circumferential inner edge, and the welding step comprises: forming the root of the weld seam in a thickness that completely encompasses at least one of the inner edges, and preferably both inner edges.

[0013] As a general rule, the suitability of the inside of the pipe element for subsequent coating increases with the proportion of the edge surface covered by the weld root. This is because the weld root provides a very reliable seal of any irregularities previously present at the edge by melting them away, and simultaneously exhibits a softer surface geometry compared to the edge surface of the hollow body. Irregularities include, in particular, cracks, fissures, capillaries, etc., in the submillimeter range, as well as sharp edges. The more of these irregularities that can be avoided, the better the expected coating success.According to the invention, a satisfactory coating is achieved when the root completely covers only one of the two edge surfaces of the first or second hollow body, while a portion of the other edge surface, particularly a radially inner portion, remains uncovered. Complete coverage of both edge surfaces is particularly preferred. It has been observed that, in the prior art, the edges of the pipe elements have already been coated during subsequent polymer finishing, particularly by applying an autodeposition process. However, contrary to previously established opinion, this has not yet been achieved with a satisfactory thickness. This reveals a further advantage of the invention: By avoiding sharp edges in the weld area through root coverage, a better coating of any remaining edges is also achieved.A sharp edge is defined as an edge angle of less than 90°.

[0014] In a preferred embodiment of the method, the root of the weld completely encompasses the circumferential inner edge of one of the hollow bodies, and the remaining inner edge of the other hollow body is spaced at the weld by a predetermined maximum value in the radial direction from the weld.

[0015] Preferably, if the wall thicknesses are the same, the predetermined maximum value is less than or equal to half the wall thickness of the hollow bodies, and more preferably less than or equal to one-quarter of the wall thickness of the hollow bodies. Alternatively, if the wall thicknesses are different, the maximum value is preferably less than or equal to the difference in the wall thicknesses of the hollow bodies, and more preferably less than or equal to half the difference in the wall thicknesses of the hollow bodies.

[0016] In a further preferred embodiment of the method, in which the welding step comprises forming the weld root with a thickness that completely encompasses the inner edges of both hollow bodies, the welding is performed such that the weld root projects radially inward from an inner surface of the wall of the first and / or second hollow body by a predetermined maximum value, wherein the predetermined maximum value is preferably 0.7 times the wall thickness of the hollow bodies or less. This slight projection of the weld into the interior of the pipe element, ensured in this way, makes it easy to verify that both edge surfaces have indeed been completely welded and that no cavities or similar features remain in the area of ​​the inner edges of the hollow bodies after welding.By limiting the maximum height by which the weld protrudes inwards, it is ensured that the weld does not create an undesirable increase in flow resistance, which would reduce the C-factor, i.e., the long-term corrosion resistance of the pipeline element.

[0017] According to the invention, the circumferential edge surface of the first hollow body is formed at one end end of the hollow body, and the circumferential edge surface of the second hollow body is spaced apart from the end ends of the second hollow body, defining a cutout through the wall of the second hollow body. This configuration is particularly relevant when the first hollow body represents a so-called connecting element, and the second hollow body represents a so-called base tube from which one or more connecting elements extend laterally. Sprinklers, for example, are connected to these connecting elements in fire extinguishing systems. The spacing of the edge surface from the end ends of the second hollow body creates a T-shaped connection between the first and second hollow bodies.Preferably, each hollow body has a longitudinal axis, and the longitudinal axes of the hollow bodies are arranged perpendicular to each other or at an angle of + / - 5° to the perpendicular. More preferably, the longitudinal axis of the first hollow body is aligned coaxially with a central axis of the cutout.

[0018] The distance of the cutout in the second hollow body from the nearest end face is preferably in a range of 20 cm to 2 m.

[0019] As an alternative to the arrangement described above, in an embodiment not belonging to the invention, the circumferential edge surface of the second hollow body is (also) formed at an end face of the second hollow body. In this embodiment, a first and second hollow body are thus joined to each other at their end faces by welding. This embodiment is particularly preferred when the first and second hollow bodies have essentially the same nominal diameter and when extended base pipe elements are to be produced by welding the first and second hollow bodies together.

[0020] In a further preferred embodiment, the method additionally comprises the step of producing at least one of the circumferential edge surfaces of the first and / or second hollow body by cutting, preferably by plasma cutting. Plasma cutting has proven to be a highly efficient method for producing the edge surfaces on the hollow bodies, particularly for wall thicknesses of 3.0 mm and above. Precise cuts at high speed and thus with high cost-effectiveness are possible. Plasma cutting is also suitable for automating the manufacturing process.

[0021] The resulting edge surface preferably corresponds to the contour of the other hollow body to which the hollow body is to be welded with its edge surface. Preferably, the contour of the edge surface to be produced is determined beforehand using measurement technology, and then the edge surface is produced according to the previously determined contour.

[0022] In a further preferred embodiment, the method further comprises the step of cleaning at least one of the circumferential edge surfaces, preferably all circumferential edge surfaces, before welding, preferably after cutting, in particular plasma cutting, and before welding. Cleaning the edge surfaces includes, in particular, the removal of burrs and loose particles, but also of contaminants. If the preceding cutting of the edge surfaces was carried out by plasma cutting, a metal oxide layer may have formed in the area of ​​the edge surface. It has been recognized within the scope of the invention that cleaning the edge surface, and in particular removing metal oxides from the surface of the hollow bodies in the area of ​​the edge surfaces, leads to a much more uniform weld pattern and results in a more uniform formation of the weld root inside the pipe element.A further advantage of this embodiment is that the cleaning of the edge surfaces can be automated with minimal effort, particularly when performed with a rotary-driven brush. Furthermore, cleaning the edge surfaces in itself also allows for an automated welding process, as this is significantly easier to control given the clean edges free of metal oxides.

[0023] In summary, the cleaning step according to the invention preferably comprises the removal of metal oxides and loose particles from the at least one circumferential edge surface, particularly preferably from all edge surfaces, preferably by means of brushes.

[0024] In a further preferred embodiment, the method according to the invention further comprises the step of flattening the wall of the first and / or second hollow body in the area where the circumferential edge surface extends or is to be generated, preferably before the welding step and more preferably before the cutting step. The flattening can be achieved by applying a deformation force to the wall of the respective hollow body from the outside, for example pneumatically, hydraulically, or mechanically. Optionally, a counter-shell the size of the area to be flattened can be placed on the underside of the pipe element as a counter-support against the hollow body from the outside, in order to prevent deformation of the pipe element at an undesired location, i.e., not at the point where the flattening is to take place.The advantage of the flattening lies in the fact that the tool used to create the weld can perform a substantially planar circular motion and does not need to be guided along a three-dimensional curve. This makes the process parameters easier to control when guiding the welding tool, and also improves control over the flow of the molten metal. Since the edge surface in the flattened area is essentially flat, the edge surface of the corresponding hollow body, which is formed on one end face, can also lie in a plane, further simplifying the cutting of the edge surface on the respective hollow body. The flattening is preferably carried out with a predetermined indentation depth, which in preferred embodiments is in the range of 0.05 to 0.18 times the nominal diameter of the flattened hollow body.

[0025] In the inventive method, the polymer-based layer is preferably applied by immersing the pipe element in a dipping bath containing a suitable coating material. The advantage of an immersion coating process is that, in addition to coating the particularly sensitive inner area of ​​the pipe elements, the outer surface is also coated, at least to a large extent, in the same coating process.

[0026] In a further preferred embodiment, the hollow bodies are made of a metal suitable for chemical autodeposition, in particular an iron- and / or zinc-containing metal, and the step of applying the polymer layer to the inside of the pipe element comprises: coating, in particular by means of chemical autodeposition, preferably by immersing the pipe element in an immersion bath containing a polymer-based chemical autodeposition material. An advantage of using an autodeposition process is, among other things, that a uniform, highly corrosion-resistant coating is achieved with simultaneously low layer thicknesses. A coating can form, particularly when using an immersion process, wherever the pipe element is wetted.Here, the advantage of the optimized welds according to the invention comes into play again, because the complete, uniform formation of the weld in the preferred embodiments described above largely avoids cavities and the like. A further advantage is that, as a result of the self-deposition layer and the corrosion protection it provides, thinner pipe wall thicknesses become possible, which were previously ruled out due to the risk of perforation. Smaller wall thicknesses, in turn, have the advantage that the surface area occupied by the welds inside the pipe can be further minimized, and that overall less material needs to be welded on.

[0027] The autodeposition material preferably contains polymeric components which are ionically bound to the wall of the hollow bodies and to the root of the weld, and is preferably in the form of an aqueous emulsion or dispersion.

[0028] The autodeposition material is preferably acidic in its liquid phase, particularly preferably having a pH value in the range of 1 to 5, and particularly preferably a starter material in the form of metal halides. For iron-containing metals, iron halides are particularly proposed, especially iron(III) fluoride. The metal halides release metal ions by reaction at the surface of the pipe elements, in the case of an iron-containing pipe element, therefore particularly iron ions, especially Fe²⁺ ions, which destabilize the polymeric components in the autodeposition material, resulting in deposition on the metal surface of the weld and the hollow body.

[0029] The autodeposition material preferably comprises autodepositionable polymers as its polymeric component, preferably selected from the list consisting of: i) Epoxides, ii) Acrylates, iii) Styroacrylates, iv) Epoxyacrylates, v) Isocyanates, in particular urethanes, such as polyurethanes, vi) Polymers with a vinyl group, for example polyvinylidene chloride, or iv) a combination of two or more of i), ii) or iii), which are preferably cross-linked together, further preferably via an isocyanate, particularly preferably via a urethane.

[0030] In the inventive method, the immersion step is continued in one or more immersion cycles until the polymer-based layer applied to the inside of the pipe element has a thickness in the range of 7 µm to 80 µm, preferably a thickness in the range of 7 µm to 30 µm. The aforementioned values ​​refer to the dry film thickness and, in particular, the increase in pipe thickness relative to the uncoated state. It has been found that layer thicknesses in the range of 7 µm and above can also be applied using the inventive method in such a way that complete coverage of the inner surface of the pipe element is achieved, as well as a large part of the outer surface, provided the immersion is carried out accordingly.

[0031] The invention has been described above in a first aspect with reference to the method according to the invention. However, the invention also relates to a piping element, in particular manufactured according to a method of the type described above.The invention solves the problem described above in the pipe element by comprising: a first hollow body, a second hollow body, wherein the hollow bodies are aligned with each other and the first and second hollow bodies are connected by means of a circumferential weld, wherein the weld is formed at an end face of the hollow body, wherein the weld is spaced apart from the end faces of the second hollow body, and wherein the weld has a root extending on the inside of the pipe element, and a polymer-based layer on the inside of the pipe element, wherein the polymer-based layer completely covers the inside of the pipe element and the root of the weld.

[0032] The piping element according to the invention fully adopts the advantages and preferred embodiments of the method according to the invention, which is why reference is made to the above statements to avoid repetition.

[0033] In a preferred embodiment of the piping element, the root of the weld completely encompasses an edge surface of one of the hollow bodies, and the piping element has inside a remaining inner edge of the other hollow body, which is spaced radially away from the weld by a predetermined maximum value.

[0034] Preferably, if the wall thicknesses are the same, the predetermined maximum value is less than or equal to half the wall thickness of the hollow bodies, and more preferably less than or equal to one-quarter of the wall thickness of the hollow bodies. Alternatively, if the wall thicknesses are different, the maximum value is preferably less than or equal to the difference in the wall thicknesses of the hollow bodies, and more preferably less than or equal to half the wall thicknesses of the hollow bodies.

[0035] In a preferred embodiment, the root of the weld completely encompasses the edge surfaces of both hollow bodies and projects radially inwards from an inner side of the first and / or second hollow body by a predetermined maximum value, wherein the predetermined maximum value is preferably 0.7 times the wall thickness of the hollow bodies or less.

[0036] In a further preferred embodiment, the wall of the first hollow body is welded at one end end to a section of the wall of the second hollow body spaced apart from the end ends of the second hollow body, in which a cutout extends through the wall. Such an arrangement of the first and second hollow bodies is also referred to as a T-arrangement. This arrangement is particularly preferred when the piping element has a connection element as the first hollow body and a main or base pipe as the second hollow body, from which one or more connection elements extend laterally. The connection elements are described in more detail below. Preferably, each hollow body has a longitudinal axis, and the longitudinal axes of the hollow bodies are arranged perpendicular to each other or at an angle of ±5° to the perpendicular.Preferably, the longitudinal axis of the first hollow body is aligned coaxially with a central axis of the cutout.

[0037] The distance of the cutout in the second hollow body from the nearest end face is preferably in a range of 20 cm to 2 m.

[0038] In an alternative preferred embodiment, the walls of the first and second hollow bodies are welded together at one end of each hollow body. In this embodiment, the hollow bodies are welded together at their ends, for example, to create a pipe element with a specific length that exceeds the dimensions of the individual hollow bodies. Welding the hollow bodies together according to the invention is particularly preferred in this embodiment for those configurations in which the first and second hollow bodies have the same or nearly the same nominal diameters. Nominal diameter deviations of up to 10% can generally be tolerated.

[0039] In another preferred embodiment, the wall of the second hollow body is flattened in a region around the cutout. In other words, the second hollow body is flattened in the wall region where the first hollow body is to be installed. This has the advantage that the corresponding edge surface of the first hollow body can be essentially flat and does not need to have a three-dimensional curvature with which the first hollow body would otherwise have to conform to the wall, since the wall is also essentially flat in the region of the flattening.

[0040] In a further preferred embodiment, the hollow bodies are made of a metal suitable for chemical autodeposition, in particular of an iron-containing and / or zinc-containing metal, and the polymer-based layer contains a metallic component, preferably in the form of metal ions, in the case of an iron-containing metal particularly preferably in the form of iron ions and in the case of a zinc-containing metal in the form of zinc ions.

[0041] The autodeposition material preferably comprises autodepositionable polymers as its polymeric component, preferably selected from the list consisting of: i) Epoxides, ii) Acrylates, iii) Styroacrylates, iv) Epoxyacrylates, v) Isocyanates, in particular urethanes, such as polyurethanes, vi) Polymers with a vinyl group, for example polyvinylidene chloride, or iv) a combination of two or more of i), ii) or iii), which are preferably cross-linked together, further preferably via an isocyanate, particularly preferably via a urethane.

[0042] In a further preferred embodiment, the polymer-based layer has a thickness in the range of 7 µm to 80 µm, particularly preferably a thickness in the range of 7 µm to 30 µm. This refers to the dry film thickness and, in particular, to an increase in thickness relative to the uncoated state.

[0043] Preferably, the second hollow body is tubular and has a nominal diameter in the range of DN 15 to DN 300, preferably DN 32 to DN 80. Alternatively, the nominal diameter ranges are in the inch system from ½" (NPS) to 12" (NPS), particularly preferably in the range of 1 ¼" (NPS) to 3" (NPS).

[0044] Preferably, the second hollow body has a longitudinal axis and a tube length in the direction of the longitudinal axis in a range of 1 m or more, more preferably in a range of 3 m or more, and particularly preferably in a range of 5 m or more.

[0045] Preferably, the first hollow body is also tubular and has a nominal diameter that is equal to or less than the nominal diameter of the second hollow body.

[0046] The first hollow body is preferably selected from the list consisting of: Pipe, nozzle, flange, end cap, reducer, elbow, or nipple.

[0047] Preferably, a fastening element is formed on the first hollow body, preferably selected from the list consisting of: Thread; groove; or flange ring.

[0048] The fastening element is preferably designed to connect fluid delivery devices, such as extinguishing nozzles, sprinklers, fluid distributors, or other piping elements, to the first hollow body. Preferably, the fastening element is at least partially made of one of the aforementioned metals suitable for chemical autodeposition, in particular an iron-containing and / or zinc-containing metal, and is at least partially provided with the polymer-based layer.

[0049] The invention has been described above with reference to a piping element and a manufacturing method for the piping element. In a further aspect, the invention also relates to a piping system of a fire extinguishing system, comprising a number of interconnected piping elements, wherein one, several, or all of the piping elements are designed or manufactured according to one of the preferred embodiments described above. The preferred embodiments and advantages of the manufacturing method and the piping element according to the invention are simultaneously the advantages and preferred embodiments of the piping system according to the invention; therefore, reference is made to the present descriptions to avoid repetition.

[0050] Particularly preferably, one, several or all of the piping elements have a tubular first hollow body and a tubular second hollow body, wherein the nominal diameter of the first hollow body is equal to or less than the nominal diameter of the second hollow body, and wherein a sprinkler, a fire extinguishing nozzle, a fluid distributor or another piping element is connected to the end face of the first hollow body facing away from the weld seam between the two hollow bodies.

[0051] The invention further relates to the use of a pipe element in a piping system of a fire extinguishing system, in which a number of pipe elements are coupled together, wherein one, several or all of the pipe elements are designed according to one of the preferred embodiments described above.

[0052] The invention is described in more detail below with reference to the accompanying figures and preferred embodiments. The figures show: Fig. 1 a schematic process flow diagram of the method according to the invention according to a preferred embodiment, Fig. 2 a schematic spatial representation of a pipe element produced according to the method according to Fig. 1 , Fig. 3a, bSide views of the piping element according to Fig. 2 , Fig. 4a-e, and Fig. 5a-eDetailed views of various preferred variants of the piping element according to the Fig. 2 and 3a, b , Fig. 6 a further detailed view of Fig. 5c , Fig. 7 a further detailed illustration of Fig. 5b,d , Fig. 8 a schematic representation of a partially flattened hollow body, and Fig. 9 a schematic partial representation of a pipe element not belonging to the invention.

[0053] In Figure 1The schematic sequence of the inventive method for producing a polymer-refined pipe element according to a preferred embodiment is shown. First, in steps 1a and 1b, a first hollow body and a second hollow body are provided. Subsequently, in a further process step 3a and 3b, edge surfaces are provided on the hollow bodies, preferably by plasma cutting. In steps 3a and 3b, the hollow bodies receive edge surfaces either on one or both of their end faces or on a wall section spaced apart from the respective end faces, the latter in the form of a cutout.

[0054] In a subsequent process step 5a, b, the first and second hollow bodies are cleaned at the edge surfaces, preferably using a rotary-driven brush. If plasma cutting was used in the previous step to create the edge surfaces, metal oxides, loose particles, and burrs produced by the brushing are removed as completely as possible.

[0055] In the next process step, the first and second hollow bodies are aligned relative to each other so that an edge surface of one hollow body is positioned as close as possible to a corresponding edge surface of the other hollow body. This alignment can be performed manually or using single- or multi-jointed robots.

[0056] In a subsequent process step 9, the previously aligned hollow bodies are welded together along their aligned circumferential edge surfaces, creating a fully circumferential weld seam with a root extending on the inside of the pipe element. Preferably, a single-layer weld seam is applied.

[0057] Following welding, the welded hollow bodies are prepared for subsequent coating in process step 21, which may itself comprise several sub-steps not shown in detail. This preparation includes cleaning the welded hollow bodies in one or more immersion baths containing, for example, pickling solution or rinsing media such as demineralized water. The exact number and arrangement of the preparation steps depend on the specifications of the coating material to be used.

[0058] The welded hollow bodies prepared in step 21 are then chemically coated in one or more immersion stages using an autodeposition process in the next process step 23. This immersion ensures that the entire inner surface, including the weld seam, as well as the outer surface of the hollow bodies, is essentially completely coated.

[0059] Following the coating of the hollow bodies and the weld seam with the polymer-based layer, a thermal post-treatment takes place in step 25. Step 25 can comprise one or more sub-steps, each involving a flash-off or tempering at predetermined temperatures and durations (low-temperature or high-temperature tempering). Optionally, the coated and post-treated pipe elements produced from the hollow bodies can be powder-coated in step 27. The powder coating is also preferably cured in a thermal post-treatment in step 25.

[0060] Following this, in step 29 the pipeline element is produced during the manufacturing process and is ready for use.

[0061] For simplicity, process step 25, the thermal post-treatment of the pipe components, is depicted as a single step. However, step 25 can involve several successive heat treatment stages, which may be carried out in one or more different facilities.

[0062] The welding process according to step 9 can be optimized, for example, by measuring the diameters and wall thicknesses of the hollow bodies, particularly in the area of ​​the edge surfaces, in a measurement step 13, which can be performed at any time between steps 1a, b, and welding step 9. Optionally, online measurement, for example, optically using gap detection, can be performed directly during the edge surface generation step. Based on the measured values, the welding parameters are then adjusted to compensate for any deviations of the measured geometry from the initial geometry for which the original welding parameters were stored. This makes it possible to compensate for the effects of deviations, such as any out-of-roundness of the hollow body, during the welding process itself.

[0063] Depending on the measured parameters, a parameter set for optimal weld application is preferably selected from a predefined table of values ​​in a process step 15. The parameters stored in the predefined table of values ​​for each diameter and wall thickness preferably include the feed rate, the path of the welding tool, the choice of filler metal, and, in the case of arc welding, the applied voltage, the feed rate of the welding wire, etc.

[0064] In a subsequent step 17, the previously determined parameters are preferably read into the welding tool or, if manual welding is to be carried out, made available to the operator so that in the subsequent step 19 the welding of the first and second hollow bodies can take place together.

[0065] With reference to Figure 1The process was explained schematically. The pipe element produced by the process, to which reference was already made in part, is described in the Figures 2 to 5a - e Several variants are explained in more detail.

[0066] In Figure 2 First, a pipe element 100 is shown, which has a first hollow body 101 and a second hollow body 102.

[0067] The first hollow body 101 has a first end end 103 and a second end end 105, at which it is welded to the second hollow body 102. The hollow body 102 has a cutout (113, cf.) at the point where it is welded to the first hollow body 101. Fig. 4 ) in its side wall 107 on.

[0068] The first hollow body 101 and the second hollow body 102 are connected by means of a single-layer, fully circumferential weld 109.

[0069] Inside the pipe element 100, the pipe element 100 has a polymer-based layer 111 that extends completely along the inner surfaces of the hollow bodies 101, 102 and also completely covers the circumferential weld 109 on the inner surface of the pipe element 100. If the pipe element was coated by an immersion process, the outer surface of the first and second hollow bodies 101, 102, as well as the weld 109, is also at least largely covered by the polymer-based layer.

[0070] In the illustrated embodiment, the first hollow body 101 is arranged approximately centrally between a first end face 108 and a second end face 110 of the second hollow body 102 and, as can be seen in particular in Figures 3a, bThe first hollow body 101 and the second hollow body 102 are aligned as coaxially as possible with a cutout 113 formed in the side wall 107 of the second hollow body 102. The first hollow body 101 and the second hollow body 102 are aligned with each other at an angle α, which can be, for example, in a range of approximately 90°.

[0071] In the Figures 4a - e and 5a - e Various details regarding the positioning of the hollow bodies relative to each other and the selection of the weld shape are shown, each along the section plane AA.

[0072] From the Figures 4a to e Different arrangement variants of the first and second hollow bodies 101, 102 in relation to each other emerge, and with them also different scenarios for the specific design of the weld seam inside the pipe element 100 (cf. Figures 1 to 3b ). The Figures 4a to eWhat they have in common is that the first basic body has an edge surface 115 at its second end face 105, and the second hollow body 102 has an edge surface 117 that defines the cutout 113. The embodiments of Figures 4a to 4e They differ primarily in the arrangement of the edge surfaces 115, 117 relative to each other.

[0073] In Figure 4aThe figure initially shows that the edge surface 115 of the first hollow body 101 projects into the opening 113 defined by the edge surface of the second hollow body 102. Preferably, the first hollow body 101 and the second hollow body 102 are aligned with each other, and the cutout 113 in the second hollow body 102 is dimensioned such that the edge surface 115 of the first hollow body 101 is in contact with the second hollow body 102 only at its outer circumferential edge, or extends completely within the cutout 113. In this way, only a comparatively small amount of material needs to be melted to achieve a completely circumferential weld, and a rapid working method is enabled. Ideally, with an arrangement according to the figure, Figure 4a create a weld seam, as seen in Figure 5ais shown. The "ideal case" here refers to a correct selection of a predefined parameter set that takes into account the exact dimensions of the hollow bodies 101 and 102 and the position of the edge surfaces 115, 117.

[0074] Unlike Figure 4a is in Figure 4b The first hollow body is chosen to be somewhat larger in diameter, at least relative to the diameter of the cutout 113. The edge surface 115 rests on the outside of the second hollow body 102. The inside of the wall of the first hollow body 101 preferably terminates flush with the edge surface 117 of the cutout 113 in the second hollow body 102. With an orientation and dimensioning according to Figure 4b When a corresponding parameter set is selected, a welding pattern is generated according to... Figures 5b,d receive.

[0075] In Figure 4c is an alignment between the first hollow body 101 and the second hollow body 102 essentially as in Figure 4asuch that the edge surface 115 with an outer circumferential edge abuts or is adjacent to the edge surface 117 of the second hollow body 102.

[0076] Unlike Figure 4a However, the material thickness of the first hollow body 101 is higher, so that a weld pattern results, again with the selection of the correct parameter set, according to Figure 5c will be hired.

[0077] Figure 4d differs in terms of the dimensions of the first hollow body relative to the second hollow body. Figure 4b The same quality of weld pattern can be expected here, which is why reference is made to the above descriptions as well as to Figures 5b,d is referred.

[0078] Figure 4e This again shows an alignment of the first and second hollow bodies 101, 102 relative to each other, as is also the case with the Figures 4a and 4c had already been selected. In contrast to the Figures 4d, 4cHowever, the material thickness of the second hollow body 102 is selected in such a way that a welding pattern according to Figure 5e sets, provided the correct parameter set is selected.

[0079] As can be seen from Figure 5a results, are at the in Figure 4a In the orientation shown, the hollow bodies 101 and 102 are ideally completely encompassed by a root 112 of the weld seam 109 at edge surfaces 115, 117, so that a smooth transition is created between an inner surface 118 of the first hollow body 101 and an inner surface 119 of the second hollow body 102. The polymer-based layer 111 can ideally be applied to this geometry. Figures 5b,d The root 112 of the weld 109 also runs completely around the entire circumference of the joint between the first hollow body 101 and the second hollow body 102. In contrast to Figure 4aHowever, only the edge surface 115 of the first hollow body 101 was completely covered by the weld 109, while the edge surface 117 of the second hollow body 102 was only partially covered. Due to the alignment and dimensions between the first hollow body 101 and the cutout 113, the root 112 of the weld 109 protrudes radially inwards from the wall 118 of the first hollow body 101 only by a predetermined maximum value h1. h1 is preferably located in a region of 0.7 times the material thickness of the wall 107 or less. The weld therefore does not impede the complete wetting of the inside of the pipe element with the polymer-based layer 111.

[0080] In Figure 5cA variant is shown in which, due to the material thickness of the first hollow body 101, the root 112 of the weld 109 does not fully encompass the edge surface 115 of the first hollow body 101, so that a portion, namely in the region of an inner edge 121 radially inward from the weld 109 relative to the first hollow body 101, protrudes. However, as long as the inner edge 121 is not more than a predetermined maximum value h2 away from the weld 109, the threshold for flow resistance caused by the remaining edge surface 115 remains within tolerable limits. Furthermore, complete wetting of the inside of the pipe element with the polymer-based layer 111 is not significantly impaired. Preferably, the value h2 is in the range of 0.5 times the difference in wall thickness of the walls 107, if they have the same wall thickness, or less.Alternatively, h2 is preferably less than the difference between the two wall thicknesses of the hollow bodies 101, 102, provided that the wall thicknesses are different from each other.

[0081] To achieve a weld pattern like in Figure 5c To obtain, preferably an alignment of the hollow bodies 101, 102 is used according to Figure 6 It is particularly preferred that the edge surface 115 of the first hollow body 101 and / or the edge surface 117 of the second hollow body 102 beveled. This significantly reduces the amount of material to be melted. Since the material thickness in the area of ​​the weld seam 109 to be produced can be very small, it is advantageous to insert a bath support 200 into the second hollow body 102, which prevents the molten metal from sagging.

[0082] In Figure 5e is analogous to Figure 5cAs shown, due to the material thickness of one of the hollow bodies, in this case the second hollow body 10, both edge surfaces of the first hollow body 101 and the second hollow body 102 are not fully covered. In this case, an inner edge 123 at the cutout 113 in the second hollow body 102 is spaced a predetermined value h3 from the root 112 of the weld 109, so that part of the edge surface 117 of the second hollow body 102 remains visible. However, provided that the value h3 does not exceed a predetermined maximum value, preferably determined as h2 above, the complete formation of a polymer-based layer 111 is not hindered, nor are the flow conditions unduly impaired. The advantages of the embodiments according to the Figures 5c and eThe advantages lie in their significantly simpler technical controllability. The diameter and material thickness tolerances of the first hollow body 101 and the second hollow body 102 can be reduced compared to the embodiments of the Figures 5a and 5b,d be more generously dimensioned, which simplifies the pre-selection of suitable parameter sets.

[0083] To achieve a weld pattern according to Figure 5b,d To obtain, preferably an alignment and preparation of the hollow bodies 101, 102 is carried out according to Figure 7 The first hollow body 101 preferably has a number of projections 125 on its edge surface 115, which may, for example, be designed as pins, and which define a predefined gap distance to the second hollow body 102 when the two hollow bodies 101, 102 are connected as shown in Figure 7The projections are shown aligned with each other. They ensure that the gap between the hollow bodies 101, 102 remains constant during welding and facilitate the creation of a weld 109 with complete root penetration of at least the edge surface 115 of the first hollow body 101, or even the edge surfaces 115, 117 of both hollow bodies 101, 102.

[0084] In Figure 8Finally, the aspect of local flattening is shown using the example of the second hollow body 102. The second hollow body 102 has been pressed in over a region B to a depth T, for example, by means of a press tool. In the flattened region B, the wall 107 of the second hollow body 102 is essentially planar. This makes it possible to form the edge surface 115 of the first hollow body 101 as a similarly planar end face, which is advantageous from a manufacturing economics perspective. Consequently, the weld seam 109 also extends essentially planarly in the flattened region B along the circumference of the edge surface 115. The depth T is preferably a function of the material thickness of the wall 107 of the second hollow body and the nominal diameter of the first hollow body 101. In preferred embodiments, the depth T lies in a range from 0.05 to 0.18 times the nominal diameter of the flattened hollow body. Figure 8 so of the hollow body 102.

[0085] In the figures described above, the invention was described in a first aspect such that the first hollow body 101 represents a connecting element, and the second hollow body 102 is a base tube. Figure 9 A pipe element 100 with a circumferential weld 109 is now shown, in which both the first hollow body 101 and the second hollow body 102 are each a base pipe. The hollow bodies 101 and 102 are arranged coaxially and axially adjacent to each other. In the unwelded state, the hollow bodies 101 and 102 each have an edge surface 115, 117 facing the other hollow body. After the weld 109 has been applied according to the invention, a root 112 of the weld 109 extends completely circumferentially within the pipe element 100.

[0086] In the unwelded state, the edge surfaces 115, 117 are each bounded by a circumferential inner edge 121, 123. In the welded state, the circumferential inner edges 121, 123 are completely encompassed by the root 112 of the weld 109. Instead of an angular, sharp transition between the hollow bodies 101, 102, the root 112 of the weld now forms a comparatively smooth transition. The root 112 of the weld 109 projects radially inside the wall 107 of the pipe element 100 by a predetermined maximum value h 1. The amount by which the root 112 projects inwards is preferably 0.7 times the material thickness of the wall 107 of the hollow bodies or less.

[0087] During preliminary tests, the welding parameters required to form the root 112 at the desired height h1 are determined for the predetermined pipe diameter (see above). Depending on the pipe diameter for the specific order, the appropriate parameter set is selected from the predefined list, and the welding process is carried out accordingly. The procedure is fundamentally the same regardless of whether the welding is automated, semi-automated, or manual.

[0088] Inside, the piping element 100 has according to Figure 9A polymer-based layer 111 is also formed, extending completely along the inner surfaces of the hollow bodies 101, 102 and also completely covering the circumferential weld 109 on the inside of the pipe 100. If the pipe element was coated using an immersion process, the outer surface of the first and second hollow bodies 101, 102, as well as the weld 109, is also at least largely covered by the polymer-based layer 111.

[0089] Taken together, the invention has succeeded for the first time in extending the application area of ​​polymer finishing to complex pipe elements with one or more welded joints. Where the prior art previously prevented successful coating due to insufficient weld quality on the inside of the pipe elements, the invention proposes an advantageous further development.

Claims

1. A method for producing a polymer-enhanced pipeline element (100), in particular a pipeline element (100) of a fire extinguishing installation, wherein the method comprises the steps: - providing a first hollow body (101) and a second hollow body (102), wherein the first and second hollow bodies (101, 102) each have a wall (107), and the wall (107) has in each case an circumferential edge surface (115, 117), wherein the circumferential edge surface (115) of the first hollow body (101) is formed at a face end (105) of the hollow body (101), and wherein the circumferential edge surface (117) of the second hollow body (102) is spaced apart from the face ends (108, 110) of the second hollow body (101) and defines a cutout (113) through the wall of the second hollow body (102), - aligning the circumferential edge surface (115) of the first hollow body (101) and the circumferential edge surface (117) of the second hollow body (102) with one another, - welding the first hollow body (101) to the second hollow body (102) along the circumferential edge surfaces (115, 117), wherein a fully circumferential weld seam (109) is generated which has a root (112) extending on the inside of the pipeline element (100), and - applying a polymer-based layer (111) to the inside of the pipeline element (100), wherein the polymer-based layer (111) completely covers the inside of the pipe element and the root of the weld seam (109).

2. The method as claimed in claim 1, wherein the edge surfaces (115, 117) of the first and of the second hollow body (101, 102) have in each case a circumferential inner edge (121, 123), and the welding step comprises: - forming the root (112) of the weld seam (109) with a thickness that completely encompasses at least one of the inner edges (115; 117) and preferably both inner edges (115, 117), wherein preferably the root (112) of the weld seam (109) completely encompasses the circumferential inner edge of one of the (121, 123) hollow bodies (101, 102), and the remaining inner edge of the other hollow body is spaced apart from the weld seam (109) by a predetermined maximum value (h2, h3) in a radial direction, wherein further preferably the predetermined maximum value (h2, h3), a) if the first and second hollow bodies have the same wall thickness, is less than or equal to half of a wall thickness of the hollow bodies, particularly preferably less than or equal to one quarter of the wall thickness of the hollow bodies, or b) if the first and second hollow bodies have different wall thicknesses, is less than or equal to a difference between the wall thicknesses of the hollow bodies, particularly preferably less than or equal to half of the difference between the wall thicknesses of the hollow bodies.

3. The method as claimed in claim 2, wherein the welding step comprises: forming the root (112) of the weld seam (109) with a thickness which completely encompasses the inner edges (121, 123) of both hollow bodies, wherein the root (112) of the weld seam (109) protrudes radially inward from an inside of the wall of the first and / or second hollow body by a predetermined maximum value, wherein the maximum value preferably amounts to 0.7 times the wall thickness of the hollow bodies or less.

4. The method as claimed in any of the preceding claims, furthermore comprising the step: generating at least one of the circumferential edge surfaces (115, 117) of the first and / or second hollow body (102) by means of cutting, preferably by means of plasma cutting.

5. The method as claimed in any of the preceding claims, furthermore comprising the step: cleaning the circumferential edge surface (115) or edge surfaces (115, 117) before the welding, preferably after the cutting, in particular plasma cutting.

6. The method as claimed in claim 5, wherein the cleaning step comprises removing metal oxides and loose particles from the at least one circumferential edge surface (115, 117), preferably by brushing.

7. The method as claimed in any of claims 3 to 6, furthermore comprising the step: flattening the wall of the first and / or second hollow body (102) in the region in which, in each case, the circumferential edge surface (115, 117) extends or is to be generated, preferably before the welding step and more preferably before the cutting step.

8. The method as claimed in any of the preceding claims, wherein the application of the polymer-based layer is performed by dipping of the pipeline element into a dip bath which contains a corresponding coating material.

9. The method as claimed in any of the preceding claims, wherein the hollow bodies are formed from a metal suitable for chemical autodeposition, in particular a ferrous and / or zinc-containing metal, and the step of applying the polymer layer to the inside of the pipeline element (100) comprises: coating, in particular by means of chemical autodeposition, preferably by dipping of the pipeline element (100) into a dip bath which contains a polymer-based chemical autodeposition material, wherein preferably the autodeposition material comprises polymer constituents which are ionically bonded to the wall of the hollow bodies and to the root (112) of the weld seam (109), and is preferably present as an aqueous emulsion or dispersion.

10. The method as claimed in claim 9, wherein the autodeposition material is acidic, preferably has a pH value in a range from 1 to 5, and preferably comprises a starter material in the form of metal halides, and / or wherein the autodeposition material has, as polymer constituent, one or more autodepositionable polymers preferably selected from the list comprising: i) epoxides, ii) acrylates, iii) styrene acrylates, iv) epoxy acrylates, v) isocyanates, especially urethanes, such as polyurethanes, vi) polymers with a vinyl group, for example polyvinylidene chloride, or iv) a combination of two or more of i), ii) or iii), which are preferably crosslinked to one another, more preferably via an isocyanate, particularly preferably via a urethane.

11. The method as claimed in claim 9 or 10, wherein the dipping step is continued in one or more dipping processes until such time as the polymer-based layer applied to the inside of the pipeline element has a thickness in a range from 7 µm to 80 µm, preferably a thickness in a range from 7 µm to 30 µm.

12. A pipeline element (100), in particular produced in a method as claimed in any of the preceding claims, having: - a first hollow body (101), - a second hollow body (102), wherein the hollow bodies (101, 102) are aligned with one another, and the first and second hollow bodies (101, 102) are connected by means of a circumferential weld seam (109), wherein the weld seam (109) is formed at a face end (105) of the first hollow body (101), wherein the weld seam (109) is spaced apart from the face ends (108, 110) of the second hollow body (102), and wherein the weld seam (109) has a root (112) extending on the inside of the pipeline element (100), and - a polymer-based layer (111) on the inside of the pipeline element, wherein the polymer-based layer (111) completely covers the inside of the pipeline element (100) and the weld seam (109).

13. A pipeline system of a fire extinguishing installation, having a number of pipeline elements (100) which are coupled to one another, wherein one, multiple or all pipeline elements are designed as claimed in claim 12.

14. The use of a pipeline element in a pipeline system of a fire extinguishing installation, in which a number of pipeline elements are coupled to one another, and wherein one, multiple or all of the pipeline elements are designed as claimed in claim 12.