Method for producing a number of pipes with a predetermined diameter, pipe, and piping system

Description

[0001] The present invention relates to a method for producing a number of pipes with a predetermined diameter. In particular, the invention relates to a method for producing a number of polymer-coated pipes with a predetermined diameter. The invention further relates to a pipe produced, in particular, by such a method, as well as to a piping system of a fire extinguishing system comprising a number of such pipes.

[0002] Pipes are a central component of fire extinguishing systems. It's not uncommon for pipelines several kilometers long to be installed in buildings to supply sprinklers, extinguishing nozzles, and the like with extinguishing agents in the event of a fire.

[0003] Processes for manufacturing piping for fire extinguishing systems are well known. Pipes in fire extinguishing systems face the particular challenge of being installed in buildings for very long periods of time without being used, yet must reliably fulfill their assigned function of transporting fluids when needed.

[0004] Fire extinguishing systems are widespread, for example, in which the piping systems carry extinguishing fluid even in the standby mode, and alternatively, those in which no extinguishing fluid is yet present in the sprinkler lines when in the standby mode. In the latter systems in particular, the susceptibility to corrosion inside the pipes is a particular challenge, which is why efforts have been made in the state of the art to reduce the corrosion resistance of pipes and piping elements, particularly for fire extinguishing systems. To circumvent the problem of corrosion within fire extinguishing systems, alternative approaches have been developed in which large sections of the piping system, and with them the majority of the installed pipes, are filled with gases rather than extinguishing fluid when in the standby mode.

[0005] EP2623163A1 shows a fire extinguishing system which consists of a pipe system.

[0006] The costs for state-of-the-art systems are sometimes considerable, as on the one hand the use of corrosion-resistant pipes or complex passivation processes were necessary, and on the other hand high installation costs were necessary for filling gas into the respective piping systems.

[0007] EP 1 2153 964 and EP 2 766 653 each describe systems and methods that achieve a significant improvement over the prior art. They describe, for the first time, the use of a polymer coating by means of autodeposition on the inside of pipe elements for fire extinguishing systems. The polymer coating described therein is extremely robust due to the achieved ionic bonding of a polymer-based coating material to the pipe surface and enables the use of simple, inherently non-corrosive metals, particularly low-alloy steel grades. At the same time, very low corrosion development, even complete corrosion resistance, is achieved even over extended observation periods.

[0008] Furthermore, pipes, especially those used in fire extinguishing systems, are required to offer the lowest possible flow resistance to the fluid being transported, such as extinguishing agents. To achieve this, the inner surface of the pipes must be as smooth as possible, which in turn also benefits corrosion resistance. For the reasons mentioned above, the manufacturing of fire extinguishing systems, in particular, is of great importance. At the same time, the industry strives to operate pipe production in a cost-efficient manner, which creates a conflicting objective, particularly with regard to the required corrosion resistance.

[0009] For practical installation at the respective site, these piping systems, often stretching several kilometers in length, require the provision of pipes of varying lengths and diameters. To minimize the need to trim the pipes to their designated lengths at the installation site, considerable effort is invested in the advance planning of the piping system.

[0010] In known pipe manufacturing processes, pipe sections of predetermined lengths are provided as starting material. The piping systems were then pieced together from the standard-length pipes. At points where shorter pipe sections were required than the standard-length pipe sections, the pipe sections were shortened to the designated lengths starting from the standard-length pipe sections, and the remaining offset pieces or pipe remnants were sorted out as offcuts. For example, if a total of ten pipe sections, each five meters long, were required to install a piping system for a fire extinguishing system, while the standard pipe length is, say, six meters or more, one meter or more of offcuts was generated for each of the ten standard pipe sections.

[0011] US 4,132,339 A further discloses a method for producing pipe strings from individual pipe sections of various lengths, wherein the pipe sections are welded together to form a pipe string by butt joining. Before the actual production of the pipe string, a model I of a reference pipe string is first created, the total length of which corresponds to the exact length of the pipe string to be produced. Prohibited zones for butt joints are then marked along the reference pipe string. Subsequently, a theoretical model II of a pipe string is created by randomly stringing together actual lengths of available pipe sections, whose lengths have previously been measured. The total length of model II exceeds that of reference pipe string I.The theoretical model II of the pipe string is then compared with the model I of the reference pipe string and, by shifting the model II relative to the model I, an arrangement is determined in which all butt joints are outside the prohibited zones and remaining pieces are as small as possible to avoid waste.

[0012] The known solutions are generally considered disadvantageous from an economic perspective.

[0013] Accordingly, the object of the invention was to provide a method of the type described at the outset which allows a more economical production of pipes with a predetermined pipe diameter, in particular pipes for piping systems of fire extinguishing systems.

[0014] The invention solves the underlying problem in such a method by the method comprising the steps: Feeding a plurality of pipe parts with the predetermined pipe diameter to a welding station, aligning a first pipe part and a second pipe part coaxially to one another and axially adjacent to one another, welding the pipe parts by means of a completely circumferential weld seam to form a pipe string, conveying the pipe string to a cutting station in a machine direction downstream of the welding station, and separating the number of pipes in a respective designated length from the pipe string.

[0015] It initially appears counterintuitive to first join several pipe sections by welding if they are to be immediately separated again afterwards, because the pipes processed in this way will in many cases have the circumferential root of the weld on the inside after being separated from the pipe string. Based on the findings of the prior art, this would have led to the expectation of a deterioration in flow resistance and was therefore not considered desirable. However, the inventors surprisingly discovered that the flow resistance is not unduly impaired if the root of the weld forms completely circumferentially inside the pipeline, because the root of the weld creates a comparatively smooth contour transition from one pipe section to the next. Furthermore, the material savings are drastically noticeable.If, to use the numerical example described above from the prior art, for example, the production of ten pipes of five meters each from ten pipes of six meters each results in a total offcut of ten times one meter, i.e., ten meters of pipe length, the process according to the invention is significantly more material-efficient: Instead of ten pipes, only nine pipes are required, which are welded to form a 54-meter-long pipe string, from which ten pieces of 5 meters each can be cut off, leaving only a 4-meter-long piece as "offcut"—in this case, no offcuts. The invention is based on the approach that a virtually endless pipe string is first created at the welding station by serially joining pipe sections. Pipes of any length can then be cut off from this pipe string in the downstream cutting station, without generating any offcuts.The invention is also based on the realization that the advantages achieved thereby far outweigh the disadvantages of introducing the additional weld seam, which were previously perceived as a prejudice.

[0016] Advantageous further developments arise from the subclaims and the following explanations.

[0017] According to the invention, a residual pipe part remains after the number of pipes have been separated, and the method comprises the step of: - transferring the residual pipe part into a buffer storage.

[0018] This allows even the remaining pipe section remaining as offcuts to be used in subsequent processes. This allows for essentially waste-free processing of the supplied pipe sections.

[0019] Preferably, the pipe parts with the predetermined pipe diameter are kept ready in a pipe storage area, and at least one of the first and second pipe parts is fed from a pipe storage area to the welding station for the process. Further preferably, the process comprises the step: Check whether a residual pipe part of the predetermined diameter is available in the buffer storage, and if so: feed a pipe part from the pipe storage and feed the residual pipe part from the buffer storage to the welding station.

[0020] Particularly preferably, the method according to the invention is carried out in a batch-based manner, wherein a batch run comprises a signed number of pipes to be produced with the predetermined diameter, and the method further comprises the steps: Determining a total length of the designated number of pipes, determining a length of the remaining pipe part in the buffer storage, if available, and determining a required quantity of pipe parts to be supplied from the pipe storage as: total length of the designated number of pipes minus the length of the remaining pipe part, divided by the predefined pipe length of the pipes in the pipe storage.

[0021] The method according to the invention is particularly economical when, for example, for a planned fire extinguishing system, the number of pipes and the designated lengths required for one or more predetermined diameters are calculated based on a predefined piping system. Then, preferably, all pipes and their respective designated lengths are grouped according to predetermined diameters and manufactured in batches. This allows for essentially waste-free production, because even after completion of an order, any remaining pipe sections in the buffer stock can be reused for subsequent orders.

[0022] The invention also enables a high degree of automation of the manufacturing process.

[0023] In preferred embodiments of the method, the pipe parts each have a wall, and the wall each has a circumferential edge surface, wherein the aligning step comprises: Aligning the circumferential edge surface of the first pipe part and the circumferential edge surface of the second pipe part with each other, and wherein the welding step comprises: welding the first pipe part to the second pipe part along the circumferential edge surfaces, creating a fully circumferential weld seam having a root extending on the inside of the pipe string.

[0024] In this regard, the invention is also based on the finding that, by applying a weld seam that extends completely around the interior of the pipe string, i.e. in a circle, an advantageous surface geometry is created by means of the weld seam root compared to the prior art, which enables complete wetting of the entire inner surface of the pipe string, including a transition area from the first to the second pipe part, with the polymer-based protective layer. The completely circumferentially extending root of the weld seam ensures a significantly smoother contour transition between the first and second pipe parts compared to the prior art, so that only then does it become possible to make more complex pipe strings or pipes, rather than just one-piece pipes, corrosion-resistant in the long term using polymer finishing.The smooth contour transition between the first and second hollow bodies offers advantages for any type of polymer finishing, but makes the pipe element particularly suitable for polymer finishing using autodeposition, as the flow conditions inside the pipe are less disrupted due to the smooth contour transition. Aligning the edge surfaces to each other 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.

[0025] Further preferably, the edge surfaces of the first and second pipe parts each have a circumferential inner edge, and the welding step comprises: forming the weld seam with a thickness that completely encompasses both inner edges, wherein the root of the weld seam protrudes radially inward from an inner side of the wall of the first and / or second pipe part by a predetermined maximum value, wherein the predetermined maximum value is preferably 0.7 times the wall thickness of the hollow bodies or less. By ensuring that the weld seam protrudes only slightly into the interior of the pipe string or pipe in this way, it can be easily ensured that both edge surfaces have actually been completely encompassed and that no cavities or the like remain in the region of the inner edges of the hollow bodies after welding.By limiting the maximum inward protrusion of the weld, it is ensured that the weld does not create undesirable increased flow resistance, which would reduce the C-factor, or the flow coefficient. The C-factor is calculated according to well-known principles using the Hazen-Williams equation.

[0026] Further preferably, the separating step comprises: Creating at least one of the edge surfaces of the remaining tube part by cutting, preferably by plasma cutting. Plasma cutting, in particular, has proven to be a highly efficient method for creating the edge surfaces on the hollow bodies. Precise cuts are possible at high speed and thus highly cost-effectively. Plasma cutting is also suitable for automating the manufacturing process.

[0027] In a further preferred embodiment, the method comprises the step: Cleaning at least one of the circumferential edge surfaces, preferably all circumferential edge surfaces of the pipe parts to be welded, before welding, preferably after cutting. Cleaning the edge surfaces particularly comprises removing burrs and loose particles, but also contaminants. If the prior cutting of the edge surfaces was carried out by plasma cutting, this may result in a metal oxide layer forming in the region of the edge surface. Within the scope of the invention, it has been recognized that cleaning the edge surface and in particular removing metal oxides from the surface of the pipe parts in the region of the edge surfaces leads to a much more uniform weld pattern and results in a more uniform development of the root of the weld seam inside the pipe string or pipe.A further advantage of this embodiment is that the cleaning of the edge surfaces can be automated with little effort, especially when performed with a rotary brush. Furthermore, the cleaning of the edge surfaces per se also allows for an automated welding process, as this is significantly easier to manage given the cleaned edge surfaces and their removal of metal oxides.

[0028] Further preferably, the cleaning step comprises removing metal oxides and loose particles from the at least one edge surface, preferably by means of brushing.

[0029] In a further preferred embodiment, the method is a method for producing a designated number of polymer-refined pipes, comprising the step: Applying a polymer-based layer to the inside of the pipes, whereby the polymer-based layer completely covers the inside of the pipes and the root of the weld.

[0030] In the process according to the invention, the polymer-based layer is preferably applied by immersing the pipes in a dip bath containing a suitable coating material. The advantage of a dip coating process is that, in addition to coating the particularly sensitive interior of the pipe elements, the outer surface is also coated, at least largely, in the same coating process.

[0031] Preferably, the pipe parts are formed from a metal suitable for chemical autodeposition, in particular from a metal containing iron and / or zinc, and the step of applying the polymer layer to the inside of the pipe comprises: coating, in particular by means of chemical autodeposition, preferably by immersing the pipe in a dipping bath containing a polymer-based chemical autodeposition material.

[0032] One advantage of using an autodeposition process is, among other things, that a uniform, highly corrosion-resistant coating with simultaneously thin layers is achieved. A coating can form wherever the pipeline element is wetted, particularly when using a dipping process. This is where the inventive advantage of optimized weld seams comes into play, because the complete, uniform formation of the weld seam in the preferred embodiments described above largely avoids cavities and the like. A further advantage is that, as a result of the autodeposition layer and the corrosion protection it provides, thinner pipe wall thicknesses are possible, which were previously impossible due to the risk of rust through penetration.Smaller wall thicknesses, in turn, have the advantage that the surface areas occupied by the welds inside the pipe can be further minimized and that overall less material needs to be welded on.

[0033] 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 seam, and is preferably present as an aqueous emulsion or dispersion.

[0034] The self-deposition material is preferably acidic in its liquid phase, more preferably it has a pH value in the range of 1 to 5, and most preferably a starter material in the form of metal halides. For ferrous metals, iron halides are particularly suggested as metal halides, particularly preferably iron(III) fluoride. The metal halides release metal ions by reaction on the surface of the pipe parts, in the case of an iron-containing pipe part, in particular iron ions, especially Fe 2+< ions. These ions destabilize the polymeric components in the self-deposition material, resulting in deposition on the metal surface of the weld seam and the pipe parts.

[0035] The autodeposition material preferably comprises autodepositionable polymers as a polymer component, preferably selected from the list consisting of: i) epoxides, ii) acrylates, iii) styroacrylates, iv) epoxy acrylates, 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 to one another, more preferably via an isocyanate, particularly preferably via a urethane.

[0036] The step of immersion in the autodeposition material preferably takes place in one or more immersions and is continued until the polymer-based layer applied to the inside of the pipe has a thickness in a range from 7 µm to 80 µm, preferably a thickness in a range from 7 µm to 30 µm. The aforementioned values refer to the dry layer thickness and in particular to an increase in thickness relative to the uncoated state. It has been found that layer thicknesses in a range from 7 µm upwards can also be applied using the method according to the invention in such a way that the inner surface of the pipeline element is completely covered, as well as a large part of the outer surface, if immersed accordingly.

[0037] The invention has been described above with reference to the method according to the invention in a first aspect. Furthermore, a pipe produced by a method according to one of the preferred embodiments described above is disclosed, which comprises: a first pipe part, a second pipe part, wherein the pipe parts are coaxially aligned with one another and connected by means of a circumferential weld seam, wherein the weld seam has a root extending on the inside of the pipe, and preferably a polymer-based layer on the inside of the pipe, wherein the polymer-based layer completely covers the inside of the pipe and the root of the weld seam. The pipe according to the invention fully incorporates the advantages and preferred embodiments of the method according to the invention, which is why, to avoid repetition, reference is made to the above explanations.

[0038] The root of the weld seam preferably completely encompasses the edge surfaces still present before the welding of both pipe parts, and projects radially inwardly from an inner side of the wall of the first and / or second pipe part by a predetermined maximum value, wherein the predetermined maximum value is preferably 0.7 times the wall thickness of the hollow bodies or less.

[0039] The pipe parts are preferably made of a metal suitable for chemical autodeposition, in particular a ferrous and / or zinc-containing metal, and the polymer-based layer contains a metallic component, preferably in the form of metal ions, particularly preferably in the form of iron ions in the case of a ferrous metal. The iron ions trapped between the polymer components ensure strong adhesion of the coating material to the pipe parts.

[0040] The autodeposition material preferably comprises autodepositionable polymers as a polymer component, preferably selected from the list consisting of: i) epoxides, ii) acrylates, iii) styroacrylates, iv) epoxy acrylates, 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 to one another, more preferably via an isocyanate, particularly preferably via a urethane.

[0041] Further preferably, the polymer-based layer has a thickness in a range of 7 µm to 80 µm, preferably a thickness in a range of 7 µm to 30 µm.

[0042] The predetermined diameter of the pipes manufactured and the pipe parts used for them is preferably in a range from DN15 to DN300, preferably from DN32 to DN 80. Alternatively, the nominal diameter ranges in the inch system are in a range from ½" (NPS) to 12" (NPS), particularly preferably in a range from 1 ¼" (NPS) to 3" (NPS).

[0043] The pipe produced according to the invention described above is used in a piping system of a fire extinguishing system having a number of pipes coupled to one another, wherein one, several, or all of the pipes are designed according to one of the preferred embodiments described above. Accordingly, in further aspects, the invention relates both to a piping system of a fire extinguishing system having a number of pipes coupled to one another, and to the use of a pipe in a piping system of a fire extinguishing system in which a number of pipes are coupled to one another, wherein one, several, or all of the pipes is / are designed according to one of the preferred embodiments described above.

[0044] The invention is described in more detail below with reference to preferred embodiments and the accompanying figures. Herein: Figure 1A schematic layout of a plant for carrying out the method according to the present invention, Figure 2A schematic flow diagram of the method according to the invention according to a preferred embodiment, Figure 3A further schematic flow diagram of the method according to the invention according to Figure 2 , and Figure 4 is a schematic partial representation of a pipe according to a preferred embodiment.

[0045] Figure 1 shows a system 50 for producing pipes with predetermined diameters and designated pipe lengths. The system 50 has a pipe storage area 51 in which a plurality of pipe sections 101 with a standard length of, for example, 6 m are stored.

[0046] Furthermore, the system has a welding station 53. The welding station has at least one welding tool 55, which is designed to weld pipe parts 101, 102 fed to it together, so that a completely circumferential weld seam 109 (cf. Fig. 4 ) which connects the adjacent pipe parts 101, 102 to one another in such a way that a root (112) of the weld seam is formed on the inside of the pipe parts 101, 102.

[0047] The welding station 53 is configured to form a virtually endless pipe string 104 from the individual pipe sections 101, 102 fed to it. In preferred embodiments, the welding tool 55 can be manually operated, semi-automated, or fully automated.

[0048] The system 50 further comprises a cutting station 57. The cutting station 57 comprises a cutting tool 59, for example, a plasma cutting device. The cutting station 57 is configured to use the cutting tool 59 to cut pipes 100 of a specified length from the pipe string 104 fed to it.

[0049] The system 50 further comprises a conveyor line 61 configured to convey the pipe parts 101, 102 in a machine direction A from the pipe storage 51 downstream, first to the welding station 53 and then to the cutting station 57. The conveyor line 61 can be configured as a single device or as a combination of several cooperating devices. For example, the pipe parts 101, 102 or pipe strands 104 and pipes 100 are transported by means of belt conveyors or the like.

[0050] The system 50 further comprises a buffer storage 63. The buffer storage 63 is configured to temporarily store residual pipe parts 102 that remain after the number of pipes 100 required for an order has been cut from the pipe string 104.

[0051] If the system 50 is to produce a number of pipes 100 with a predetermined diameter, the remaining pipe parts 102 located in the buffer storage can be removed from there and fed to the conveyor line 61 upstream of the welding station 53 in order to be welded together with the pipe parts 101 located in the pipe storage to form a pipe string.

[0052] If the buffer storage 63 does not have any remaining pipe parts 102 in the predetermined pipe diameter, the pipe string can also be formed exclusively with pipes 101 from the pipe storage 51.

[0053] The buffer storage 63 is preferably designed to accommodate residual pipe parts 102a, 102b of different pipe diameters.

[0054] In Figure 2 the basic process sequence of the method according to the invention is shown according to a preferred embodiment.

[0055] In a first step 1, an order is placed to produce a predetermined number of pipes 100 with a predetermined diameter. Each of the pipes 100 to be produced has a designated length, which may vary from pipe to pipe or may be identical.

[0056] After receiving the order, the total length of all pipes 100 to be produced and how many pipe parts 101 from the pipe storage 51 are required to complete the order are optionally determined in a next process step 3.

[0057] If a residual pipe section 102 is still available in the buffer storage 63, it is included in the completion of the order. Any residual pipe section remaining after the completion of the order is finally returned to the buffer storage 63.

[0058] If computer-aided order planning is used that calculates the raw material requirements, and if it is determined in a subsequent process step 5 that one or more remaining pipe sections 102 of the predetermined pipe diameter are still in stock in the buffer storage 63, the length of the remaining pipe sections available in the buffer storage 3 can be subtracted from the required total length. The result, divided by the length of the pipe sections 101 located in the pipe storage 51, then yields the number of pipe sections 101 required from the pipe storage 101.

[0059] If it is determined in method step 5 that one or more residual pipe parts 102 of the predetermined diameter are available in the buffer storage 63, these are fed to the conveyor line 61 in a next method step 7.

[0060] In addition, the required pipe parts 101 are successively fed from the pipe storage 51 to the conveyor line 61 in a process step 9. If no residual pipe parts 102 of the predetermined diameter are available in the buffer storage 63, the pipe part requirement for the placed order is met exclusively with pipe parts 101 from the pipe storage 51. The pipe parts 101 and, if applicable, residual pipe parts 102 are fed to the welding station 53 and welded together in a next step 11.

[0061] After welding, the pipe string 104 produced by welding is fed to the cutting station 55, and in a next process step 21, the pipes 101 are cut from the pipe string 104 in the required designated lengths. If a residual pipe section 102 remains after cutting the required number of pipes 100, it is fed to the buffer storage 63 in a next process step 22.

[0062] After separation, a selection step 23 determines whether the separated pipes 100 can be forwarded directly to surface finishing or whether further welding steps, in particular the attachment of weldable parts to the pipes, should be performed first. If the pipes are to be further processed without weldable parts, they are removed from the conveyor line 63 after separation in step 21 and prepared for surface finishing in a subsequent process step 29.

[0063] If the selection is made that the separated pipes 100 are to be further processed by attaching further welded parts, these are fed as second hollow bodies to a process step 25b, cf. Figure 3 .

[0064] In Figure 3 The additional attachment of welded parts to the pipes 100 is shown schematically. First, in steps 25a, 25b, a first hollow body, for example a pipe socket for receiving a sprinkler, and a pipe 100 produced from the pipe string 104 are provided as a second hollow body. Subsequently, in a next method step 39a, b, edge surfaces are provided on the hollow bodies, preferably by means of plasma cutting. In steps 39a, b, the hollow bodies receive edge surfaces either on one or both of their end faces or on a wall section spaced from the respective end faces, the latter in the form of a cutout.

[0065] In a subsequent process step 41a, b, the first and second hollow bodies are cleaned at their edge surfaces, preferably using a rotary brush. If plasma cutting was used to create the edge surfaces in the previous step, metal oxides, loose particles, and burrs created by the brushing are removed as far as possible.

[0066] In a next process step 43, the first hollow body and the second hollow body are aligned relative to each other such that an edge surface of one hollow body is aligned and positioned as closely as possible to a corresponding edge surface of the other hollow body. The alignment of the hollow bodies relative to each other can be performed manually or by means of single- or multi-jointed robots.

[0067] In a next process step 45, the previously aligned hollow bodies are welded together along the aligned circumferential edge surfaces, creating a fully circumferential weld seam with a root extending along the inside of the tube. Preferably, a single-layer weld seam is applied.

[0068] Following welding, the hollow bodies welded together are returned to the process step 27 as pipes with weld-on parts, which the pipes 100 without weld-on parts also go through.

[0069] In a process step 29, which may in turn comprise several sub-steps not shown in detail, the pipes 100 are prepared for subsequent coating. The preparation involves cleaning the pipes in one or more immersion baths, in which, for example, pickling agents or rinsing media such as demineralized water can be stored. The exact number and arrangement of the preparation steps depends on the specifications of the coating material to be used.

[0070] The hollow bodies prepared in step 29 are then chemically coated in one or more immersions using an autodeposition process in a subsequent process step 31. This immersion ensures that the entire inside, including the weld seam, as well as the outside of the hollow bodies, are essentially completely coated.

[0071] Following the coating of the hollow bodies and the weld seam with the polymer-based layer, a thermal post-treatment takes place in a step 33. Step 33 can comprise one or more sub-steps, each of which involves a flash-off or a tempering process at predetermined temperatures and durations (low tempering or high tempering). Optionally, the coated and post-treated pipes produced from the pipe parts can be powder-coated in a step 35. The powder coating is also preferably cured again in a drying process in step 33.

[0072] Subsequently, in step 37, the pipe is removed from the manufacturing process and is ready for use.

[0073] For the sake of simplicity, process step 33 for the thermal post-treatment of the tubes is depicted as a single step. However, step 33 can involve several consecutive heat treatment stages, which can be performed in one or more different facilities.

[0074] The welding process according to steps 11, 45 can be optimized, for example, by measuring the diameters of the pipe parts and the wall thicknesses of the pipe parts, particularly in the area of the edge surfaces, in a measuring step 13, which can be carried out at any time between steps 7, 9 or 25a,b and the respective welding step 11, 45.

[0075] Optionally, online measurement, for example, optically using gap detection, is performed directly during the edge surface generation process step. Based on the measured values, the welding parameters are then adjusted to compensate for any detected deviations of the measured geometry from the initial geometry for which the original welding parameters were stored. This allows the effects of the deviations, such as any out-of-roundness of the hollow body, to be compensated for during the welding process itself.

[0076] Depending on the measured parameters, a set of parameters for optimal weld seam placement is preferably selected from a predefined value table in a method step 15. The parameters stored in the predefined value table for each diameter and wall thickness preferably include the feed rate, the filler metal material, and the welding type. If, for example, arc welding is selected as the welding type, the parameters of the welding tool 55 also include the voltage, the feed rate of the welding wire, etc.

[0077] In a subsequent step 17, the previously determined parameters are preferably read into the welding tool or, if welding is to be carried out manually, are made available to the operator so that the welding of the first and second hollow bodies can take place in the subsequent step 19.

[0078] In Figure 4A pipe 100 or, optionally, a portion of the pipe string 104 is shown in the region of the circumferential weld seam 109 produced in the welding station 51. The pipe parts 101 and 102 are arranged coaxially to one another and axially adjacent to one another. In the unwelded state, the pipe parts 101 and 102 each have an edge surface 115, 117 facing the other pipe part. After the weld seam 109 has been applied according to the invention, a root 112 of the weld seam 109 extends circumferentially, completely in a circle, within the pipe string 104 or pipe 100.

[0079] In the unwelded state, the edge surfaces 115, 117 are each still delimited 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 seam 109. Instead of an angular, sharp transition between the pipe parts 101, 102, the root 112 of the weld seam 109 now forms a comparatively smooth transition. The root 112 of the weld seam 109 protrudes radially within the wall 107 of the pipe 100 or pipe string 104 by a predetermined maximum value t 1 . The amount by which the root 112 protrudes inward is determined by the pipe diameter of the pipe parts 101, 102, the material thickness of the wall 107, and the welding parameters of the welding tool 55.

[0080] During preliminary tests, the welding parameters required to form the root 112 at the desired depth t1 for the specified pipe diameter are determined (see above). Depending on the pipe diameter required for the particular job, the appropriate parameter set is selected from the predefined list and the welding process is performed using this parameter. The procedure is fundamentally the same, regardless of whether the welding is automated, semi-automated, or manual.

[0081] Furthermore, in Figure 4Reference numeral 111 denotes the polymer-based protective layer applied to the inside of the pipe 100 at the end of the process, which has the properties described above in the general section. Inside the pipe 100, the pipe 100 has a polymer-based layer 111 that extends completely along the inside of the hollow bodies 101, 102 and also completely covers the circumferential weld seam 109 on the inside of the pipe 100. If the pipe was coated using a dipping process, the outer surface of the first and second hollow bodies 101, 102 and the weld seam 109 are also at least largely covered by the polymer-based layer.

Claims

1. A method for producing a number of pipes (100) with a predetermined pipe diameter, comprising the steps: - feeding multiple pipe parts (101, 102) with the predetermined pipe diameter to a welding station (53), - aligning in each case a first pipe part (101) and a second pipe part (102) coaxially with respect to one another and axially adjacent to one another, - welding the pipe parts (101, 102) by means of a fully encircling weld seam (109) to form a pipe run (104), and - conveying the pipe run (104) to a cutting station (57) in a machine direction (A) downstream of the welding station (53), characterized by - cutting off the number of pipes (100) in a respectively designated length from the pipe run (104), wherein after the cutting-off of the number of pipes, a residual pipe part (102) remains, and the method comprises the step: - transferring the residual pipe part (102) into a buffer store (63).

2. The method as claimed in claim 1, wherein at least one of the first and second pipe parts (101) is guided from a pipe store (51) to the welding station (53), wherein preferably the method comprises the step: - checking whether a residual pipe part (102) of the predetermined diameter is available in the buffer store (63), and - if so: feeding a pipe part (101) from the pipe store (51) and feeding the residual pipe part (102) from the buffer store (63) to the welding station (53).

3. The method as claimed in claim 2, wherein the method is carried out in batch-based fashion, wherein a batch run comprises a designated number of pipes (100) to be produced, and the method comprises: - determining a total length of the designated number of pipes (100), - determining a length of the residual pipe part (102) in the buffer store (63), if present, and - determining a required quantity of pipe parts (101) to be fed from the pipe store (51) as: total length of the designated number of pipes minus the length of the residual pipe part, divided by the predefined pipe length of the pipes in the pipe store.

4. The method as claimed in any of the preceding claims, wherein the pipe parts (101, 102) each have a wall (107), and the wall (107) has in each case an encircling edge surface (115, 117), and the aligning step comprises: - aligning the encircling edge surface (115) of the first pipe part (101) and the encircling edge surface (117) of the second pipe part (102) with one another, and the welding step comprises: - welding the first pipe part (101) to the second pipe part (102) along the encircling edge surfaces (115, 117), wherein a fully encircling weld seam (109) is generated which has a root (112) extending on the inside of the pipe run (104).

5. The method as claimed in claim 4, wherein the edge surfaces (115, 117) of the first and of the second pipe part (101, 102) have in each case an encircling inner edge (121, 123), and the welding step comprises: - forming the root (112) of the weld seam (109) with a thickness that completely encompasses both inner edges (115, 117), wherein the root (112) of the weld seam (109) protrudes radially inward from an inside of the wall of the first and / or second pipe part by a predetermined maximum value (t1), wherein the predetermined maximum value preferably amounts to 0.7 times the wall thickness of the pipe parts or less.

6. The method as claimed in any of the preceding claims, wherein the cutting-off step comprises: generating at least one of the edge surfaces (117) of the residual pipe part (102) by means of cutting, preferably by means of plasma cutting.

7. The method as claimed in any of claims 4 to 6, furthermore comprising the step: cleaning the edge surface (115, 117) before the welding, preferably after the cutting, wherein preferably the cleaning step comprises removing metal oxides and loose particles from the at least one edge surface (115, 117), preferably by brushing.

8. The method as claimed in any of the preceding claims, wherein the method is a method for producing a designated number of polymer-enhanced pipes, comprising the step: - applying a polymer-based layer (111) on the inside of the pipes, wherein the polymer-based layer completely covers the inside of the pipes and the root of the weld seam, wherein preferably 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 pipe parts 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 on the inside of the pipe (100) comprises: coating, in particular by means of chemical autodeposition, preferably by dipping of the pipe (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, wherein further preferably the autodeposition material is acidic, preferably has a pH in a range from 1 to 5, and preferably comprises a starter material in the form of metal halides, in particular iron halides, particularly preferably iron(III) fluoride, by means of which the polymer constituents are destabilized.

10. The method as claimed in claim 9, wherein the autodeposition material has, as polymer constituent, 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 any of claims 9 or 10, wherein the dipping step is performed in one or more dipping processes and is continued until such time as the polymer-based layer applied to the inside of the pipe (100) 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 system of a fire extinguishing installation, having a number of pipes (100) which are coupled to one another, characterized in that one, multiple or all pipes is / are produced according to a method as claimed in any of the preceding claims, wherein the pipe (100) comprises: - a first pipe part (101), - a second pipe part (102), wherein the pipe parts (101, 102) are aligned coaxially with respect to one another and connected by means of an encircling weld seam (109), wherein the weld seam (109) has a root (112) extending on the inside of the pipe (100), and preferably - a polymer-based layer (111) on the inside of the pipe, wherein the polymer-based layer (111) completely covers the inside of the pipe (100) and the root of the weld seam (109).

13. The use of a pipe in a pipeline system of a fire extinguishing installation, in which a number of pipes are coupled to one another, characterized in that one, multiple or all pipes is or are produced according to a method as claimed in any of the preceding claims, wherein the pipe (100) having: - a first pipe part (101), - a second pipe part (102), wherein the pipe parts (101, 102) are aligned coaxially with respect to one another and connected by means of an encircling weld seam (109), wherein the weld seam (109) has a root (112) extending on the inside of the pipe (100), and preferably - a polymer-based layer (111) on the inside of the pipe, wherein the polymer-based layer (111) completely covers the inside of the pipe (100) and the root of the weld seam (109).