MXPA96004658A - Metal pipe with covering completely formed and my manufacturing method - Google Patents

Abstract

The present invention relates to a method for forming a polymer-laminated metal tube, characterized in that it comprises the steps of: (a) providing a steel sheet having a coextruded polymer layer of ethylene acrylic acid and a polyethylene / ethylacrylic acid combination formed on at least one surface thereof, (b) passing the steel sheet through a profiling former to form channels and seaming members therein; (c) forming the steel sheet into a section of pipe; and (d) placing a coating of the heated polyethylene in layered juxtaposition to the coextruded polymer layer of the ethylene acrylic acid and the polyethylene / ethylene acrylic acid combination that is formed on the steel sheet subsequent to the forming step of the steel sheet in a section of your

Description

METAL PIPE WITH COVERING COMPLETELY FORMED AND METHOD OF MANUFACTURE OF THE SAME RELATED REQUESTS This is a continuation in part of the US patent application Serial Number 07 / 736,108, filed on July 26, 1991 and entitled METAL PIPE WITH INTEGRALLY-FORMED COATING AND METHOD OF MAKING IT, the content of which is incorporated herein. as reference.

FIELD OF THE INVENTION The present invention relates generally to a buried pipe for use in sewers, storm sewers, drains, intake channels, sewers and other low load applications, and more particularly with a metal pipe with a formed coating integrally for use in corrosive and abrasive environments and a method to manufacture it.

REF: 23321 BACKGROUND OF THE INVENTION The corrugated design metal pipe and spiral flange is widely used for drainage, sewer and other similar fluid conduits. Although it is susceptible to abrasion, the steel tube has advantages over the concrete pipe and the like due to its comparatively high strength and low weight. These characteristics mean that the metal tube is relatively inexpensive to manufacture, transport and handle, which at the same time allow its use in applications that require substantial land support. In addition, in recent years a steel pipe with special spiral flanges has been introduced by .E. Hall Co., of Newport Beach, California, the beneficiary of the subject application, which possesses hydraulic efficiency comparable to the more expensive concrete pipe as well as having superior structural capabilities for prolonged use in buried stormwater collector applications. Since the metal pipe is susceptible to corrosion and excessive abrasion, its use has consequently been restricted mainly to sewer and stormwater collector applications. In sanitary applications, that is, in sewer systems, corrosion is caused by the sulfuric acid that is formed from the hydrogen sulfide generated by the waste products. Such waste products and / or acid convert the use of the steel tube into inappropriate sanitary applications since it deteriorates rapidly in the corrosive environment. As such, the concrete pipe, coated with concrete and / or glass clay much heavier and more expensive has traditionally been used for sanitary applications. Thus, although the metal tube is generally preferred due to its high strength and relatively low weight and cost, the metal tube has not so far been widely used in sanitary applications due to its susceptibility to corrosion. In rainwater collector applications, such a metal pipe is particularly susceptible to extensive abrasion caused by the movement of gravel, dust, dirt, etc. through him. Such excessive abrasion often degrades the metal point to a point where the leakage of the contents of the tube becomes a major concern. Additionally such abrasion can, in some cases, be sufficient to adversely affect the structural integrity of the tube, and consequently result in structural failures of the tube where the rubble soil crushes a portion of the tube, thereby effectively blocking the tube. and substantially reducing or eliminating the flow through it.

Recognizing these deficiencies, the prior art attempted to admit the use of the concrete pipe as opposed to the vitreous clay pipe for large sewer applications, while reducing the susceptibility to corrosion of the concrete pipes that have been included. : the installation of a corrosion-resistant plastic coating, and / or the formation of the interior of a concrete pipe with an additional sacrifice of concrete in the crown portion of the pipe. Such corrosion resistant coatings of the prior art typically comprise plastic inserts sized to be received within each section of concrete pipe. Such coatings are commonly molded into each section of the tube. Subsequently after the tube sections have been coated in place, the adjacent coatings are joined with the intention of forming a seal to prevent the fluids and corve gases from coming into contact with the concrete pipe. Although such concrete tube / plastic coating solutions of the prior art have generally proven to be suitable for applications to large sewers, the inherent high cost of such solutions has posed a severe impediment in the construction of the products. Furthermore, the lifespan of such sacrificial concrete tube solutions of the prior art is finite, which require a general rehabilitation over time, thus demanding tremendous costs in the costs of upward rehabilitation. In recognition of the general inability of the metal pipe and the concrete pipe for sewer applications, in recent years the plastic pipe has been introduced to the market. Although such a plastic tube withstands the degradation caused by the corve environment encountered in sewer applications, its use so far has been limited mainly to applications of small-sized sewers. In this regard, the structural integrity of the plastic tube is extremely limited so that in large applications, the side wall of such a plastic tube must be made extremely thick or shaped to allow such a plastic tube to resist the compressive forces exerted. in underground applications. Due to the high cost of such plastic material, the use of such a plastic tube in large-scale sewer applications has been economically impractical. Therefore, in view of the specific factors found in large-scale sanitary sewer applications, all these applications have used the expensive concrete pipe that has a sacrificial wall formed therein, which decays significantly during prolonged use and thus will require expensive rehabilitation and / or replacement over time. In contrast, the waste products and / or acidic environment found in sanitary applications, the metal tube used for underground pluvial plumbing applications additionally encounter substantial problems associated with their operating environments. In relation to the applications of underground rainwater collectors, the long-term exposure of the exterior of the metal tube within the underground environment serves to corrode the exterior of the tube while the water and debris flowing through the interior of the tube Metal degrade the tube through abrasion. In an effort to prevent such corve effects, the interior of the metal pipe has been coated with concrete in the hope that a coating or thickness could be more resistant to abrasion and therefore resist deterioration and coron. However, there are no flawless means to anchor the concrete to the inner wall of the metal pipe. As a result, the pieces of the concrete lining inevitably come off the pipe. When combined with the continuous abrasive action that occurs in it, it rapidly destroys the protective layer of concrete. Additionally, concrete is susceptible to cracking and breaking as a result of poor handling, earth movement and thermal stress. Such cracking and breaking results in coron of the steel surface in the vicinity of breaking or cracking. An alternative method of the prior art for solving the coron and abrasion deficiencies of the metal tube for rainwater collector applications has been to fabricate the metal tube from steel material laminated with a plastic film. One such prior art product is known as Black-Klad, a product of the Inland Steel Company of Chicago, Illinois. Before winding the steel sheet in a section of pipe, a surface, ie that surface that forms the inner surface of the pipe, it is laminated with a polymeric material such as a polyethylene compound. The thickness of such lamination is limited to approximately 0.254 millimeters (0.010 inches) and is intended to resist the degradation caused by corrosion and some abrasion. However, due to the comparatively thin layer thickness of the plastic laminate, the laminate tends to wear through it due to abrasion of sand, rocks, etc. and therefore exposes the metal surface below it. In addition, during the tube forming process, the thin laminate is often damaged due to the cold rolling forming processes of the metal. Attempts to apply thicker laminations to such prior art products have so far resulted in greater vesiculation and separation of the polymeric compound from the metal tube. As such, the application of a protective polymer layer to the metal tube has so far been poor. Therefore, because the coating of approved prior art metal tubes is susceptible to abrasion and corrosion, and since inert abrasion resistant coatings such as those constructed of concrete or an inert polymeric material have failed. In remaining effectively anchored to the walls of the metal tube, the metal tube has not been acceptable so far for use in sanitary applications such as sanitary sewers. Therefore, there is a substantial need in the art for a sufficiently thick coating or coating that can be securely applied to the metal surfaces to maintain the integrity of the metal when the metal tube is placed in a corrosive environment and for remain on it without vesiculation during the process of tube formation. In addition, there is a substantial need in the art for an improved metal tube with an inert protective coating constructed of a polymeric material such as polyethylene that could withstand the attack of sulfuric acid as well as withstanding other forms of corrosion encountered in sewer applications.

BRIEF DESCRIPTION OF THE INVENTION The present invention specifically addresses and alleviates the deficiencies referenced above associated with the prior art. More particularly, the present invention comprises a metal tube with an integrally formed coating for use in corrosive and abrasive environments. In the preferred embodiment of the present invention, the coating is comprised of high density polyethylene from 1.27 to 3.175 millimeters (0.050 to 0.125 inches) thick, which is securely attached to the metal pipe during the manufacture of the metal pipe . Optionally linear low density polyethylene can be used instead. However, other polymers that have corrosion resistant properties similar to those of polyethylene were contemplated in the same way here. The coating is formed by applying a thin coextruded film of ethylene acrylic acid and a polyethylene / ethylene acrylic acid mixture to the surface of the metal tube and subsequently extruding a comparatively thick layer of high density polyethylene thereon. The coextruded film is applied in a pretreatment process to the metal sheet, before forming the stamped profile of the corrugations or flanges in the rolled steel. The relatively thick high density polyethylene layer is applied after the corrugations or flanges have been formed in the rolled metal and either before or after the helical winding and forming of the rolled steel in pipe sections. The coextruded film is specifically formed to securely adhere to the surface of the laminated metal and provide a film or top layer suitable for the subsequent thermal bonding of a relatively thick layer of high density polyethylene. Thus, the coextruded film serves as a strong bonding agent, which is adhesively bonded to the metal tube and additionally forms a suitable polyethylene base material to allow subsequent application of a relatively thick layer of polyethylene from high density on this. Thus, the present invention provides a uniform, hydraulically efficient interior surface, which is resistant to the corrosive action of sulfuric acid and the like, specifically found in sanitary applications. It is also highly resistant to abrasion caused by the flow of debris carried by water such as dust and gravel found in sewers and rainwater collector applications. The metal tube forming process of the present invention begins with the step of pre-washing the rolled metal to remove any remaining oil and dust. The rolled metal is subsequently bathed in an alkaline solution to remove chromates and then rinsed. The alkaline bath and the rinse are preferably repeated and the rolled metal is then attacked with an etching solution and then dried. Optionally, a primer coating of an adhesive can then be applied and the rolled metal heated to cure the particular applications. Preferably, a layer of coextruded polymer of ethylene acrylic acid and a polyethylene / ethylene acrylic acid mixture is subsequently applied to the metal or if the primer coating to which it adheres is used. Subsequently, the pre-treated metal sheet is cooled and rolled and then formed by conventional techniques to include corrugations or ridges. Subsequently, the pretreated and corrugated rolled metal is heated and a molten layer of polymer, high density polyethylene is extruded for example, onto the pretreated rolled metal which typically has a thickness of about 1.27 to 3.175 millimeters (0.050 to 0.125 inches). Because the polyethylene is applied at a high plasticization temperature, it is thermally bonded securely to the layer of extruded film previously applied to the rolled metal to provide a corrosion resistant and composite abrasion tube. In the preferred mode, the application of the relatively thick layer of high density polyethylene can be applied either before or after the formation of the corrugated rolled metal in tube lengths. Subsequently, the tube sections are cooled and cut to the desired lengths using conventional techniques. Although described in relation to the specific application for tube forming applications, the present invention is further applicable to other metal forming applications where the chemical resistance of the fabricated metal product is required. In addition to being thermally bonded to the coextruded film layer, the relatively thick high density polyethylene layer can be further secured to the rolled metal via the use of captured anchors within the tapered channels of the tube and attached to the polyethylene layer high density Various means were contemplated to attach the anchor to the high density polyethylene layer. The high density polyethylene layer can be forced along the anchor in the tapered channel so that the high density polyethylene layer can be forced along the anchor in the tapered channel so that the high polyethylene layer The density substantially surrounds the anchor and is captured within the tapered channel. The anchor is preferably comprised of a polymeric material compressible so that it can be forced through a narrow opening in a tapered channel and then expanded so as to remain captured therein. Optionally, the anchor may comprise a hollow center extending substantially the entire length thereof to facilitate such compression. Alternatively, the anchor may comprise a high density polyethylene core substantially surrounded by a linear low density polyethylene cover. Alternatively, the anchor may be placed first within the tapered channel and then the high density polyethylene layer applied to the coextruded film layer as described above. The anchor is attached or attached to the high density polyethylene layer. Those skilled in the art will recognize that various means, i.e. thermal bonding and / or the use of adhesives or chemical bonding agents, are suitable for attaching the anchor to the high density polyethylene layer. Alternatively, a polyethylene layer can be attached to the anchor prior to insertion of the anchor into the tapered channel so that a portion of the polyethylene layer extends outwardly through the opening in the tapered channel through which it can be joined. thermally or adhesively to the high density polyethylene layer. Alternatively, the anchor can be formed to have an integral portion, which extends through the aperture of the tapered channel and to which the high density polyethylene layer can be thermally or adhesively bonded. Alternatively, the anchor may be placed within the channel before forming the tapered sides of the channel where a narrow opening is formed. The use of a non-compressible anchoring material is thus facilitated in the likelihood that the anchor is pulled undesirably through the opening of the tapered channel is mitigated.

Alternatively, a non-tapered or rectangular channel and an anchor of complementary shape placed therein may be provided prior to the application of the relatively thick high density polyethylene layer. The rectangular anchor can be rolled in the channel in such a way that it resists the removal of the channel. For example, a relatively straight anchoring material can be bent during the isolation process so that the tendency of the material to be strained forces it outwards and thus deepens it into the channel, thereby maintaining its position therein. Alternatively, the anchor can be extruded directly into the channel. The relatively thick high density polyethylene layer is then applied immediately on top of it so that the anchor and the high density polyethylene layer are firmly bonded together. Such thermal bonding is facilitated by the placement of both the anchor extruder and the extruded high density polyethylene layer in close proximity to each other and in close proximity to the tube formed. Thus, instead of applying a preformed anchor to the channel, as discussed above, the anchor is extruded or formed directly in the channel, and therefore precisely conforms to the configuration of the channel, i.e., substantially fills the channel , and additionally it is thermally bonded to it. The extrusion of the anchor in the channel preferably occurs after the tube has been formed, that is, after the interconnection of the seams connecting the wall sections adjacent to each other. The extrusion of the anchor in the channels may occur as a single extrusion, or alternatively, may comprise a plurality of extrusions. For example, in a double extrusion process approximately one half of the anchor is formed by first extruding it in the lower portion of the channel and the remainder of the anchor is subsequently formed by applying a second extrusion on the previously extruded portion of the anchor. Those skilled in the art will recognize that various extrusion members may be used in such multiple extrusion processes, as desired. A plurality of channels can be filled simultaneously or each channel can be filled individually, as desired. Additionally, the anchor extruded into the channel may extend beyond the channel thereby forming layers on the inner surface of the tube to increase the available surface area to join the subsequently applied high density polyethylene layer. For example, the anchor may extend perpendicular to the channel for a distance along either side of the channel on the inner surface of the tube, or alternatively, may extend upwardly from the channel for a desired distance. Those skilled in the art will recognize that several such configurations are equally acceptable for increasing the surface area of the anchor to facilitate better attachment to the subsequently applied high density polyethylene layer. Alternatively, the anchor and the high density polyethylene layer can be commonly extruded from a single extruder so that the channel is filled to form the anchor and the high density polyethylene layer is applied to the inner surface of the tube simultaneously . The extruder is configured in such a way that an amount of polyethylene is initially provided in those areas of the tube where the channel is formed and an additional coated amount of polyethylene is provided on the inner surface of the tube, and extending over the channels. In this way, the manufacturing process is simplified by reducing the number of required extruders and by eliminating the requirements for the union between the anchor and the high density polyethylene layer since both are extruded integrally.

These, as well as the other advantages of the present invention will be more apparent from the following description and drawings. It should be understood that changes can be made to the specific structure shown and described within the scope of the claims without departing from the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of the exterior of a tube length constructed in accordance with the present invention; Figure 2 is an enlarged cross-sectional view of the wall of the tube of Figure 1, taken around the lines 2-2 of Figure 1; Figure 3 is a flow diagram of the method of forming the metal tube with an integral coating of the present invention; Figure 4 is a perspective view of the apparatus for forming the metal tube with a coating formed integrally by the present invention; Figure 5 is an enlarged perspective view of the tube former of Figure 4; Figure 6 is an elongated sectional view of the rolled metal after the ridges have been formed but before folding or crimping; Figure 7 is a sectional view describing the crimped seaming process of the fold; Figure 8 is a sectional side view describing the bending of the liner on the crimped seam; Figure 9 is a flow diagram of the pretreatment process, pre-coating for joining the layer of coextruded film to the rolled metal; Figure 10 is an elongated cross-sectional view of a portion of the liner and the steel tube showing the resultant coextruded film layer and the high density polyethylene layer formed on the inside of the tube layer. FIG. 1a is a cross-sectional side view of a tapered channel having a solid anchor corrugated from a single material placed therein, wherein a layer of relatively high density polyethylene has been forced into the tapered channel together with the anchor; Figure 11b is a cross-sectional side view of a tapered channel having a hollow anchor placed therein, wherein the relatively thick, high density polyethylene layer has been forced therein as in the case of a lining; Figure 12 is a cross-sectional view of a tapered channel having an anchor placed therein, wherein the anchor has been attached to the relatively thick, high density polyethylene layer; Figure 13 is a cross-sectional side view of a tapered channel having an anchor placed therein, and having a polymer layer substantially surrounding the anchor and extending from the aperture of the tapered channel so that the high polyethylene layer density, relatively thick, is attached to it; Figure 14 is a cross-sectional side view of a tapered channel having an integral anchor and connection member, wherein the anchor is deposited within the tapered channel V the connection member extends through the opening thereof, of so that the relatively thick, high-density polyethylene layer joins it; Figure 15 is a cross-sectional side view of a non-tapered channel; Figure 16 is a cross-sectional side view of a non-tapered channel having an anchor deposited thereon; Figure 17 is a cross-sectional side view of the channel and anchor of Figure 16 after the side walls of the channel have been tapered to capture the anchor therein; Figure 18 is a cross-sectional side view of a non-tapered channel having a rectangular anchor deposited thereon; Figure 19 is a cross-sectional side view of a tapered channel having an anchor formed or extruded directly therein to substantially fill the channel and also having a portion of the anchor extending from the channel to increase the surface area for contact with the high density polyethylene layer; Figure 20 is a cross-sectional side view of a tapered channel 6 having an anchor formed or extruded directly therein, wherein the anchor has a convex or domed upper surface upward to increase contact with the high density polyethylene layer; Figure 21 is a cross-sectional side view of a tapered channel having an anchor formed or extruded directly therein and having wings extending a substantial distance from the anchor onto the inner surface of the tube to substantially increase the area surface for contact with the high density polyethylene layer; Figure 22 is a cross-sectional side view of a tapered channel having a first amount of anchoring material deposited thereon; Figure 23 is a cross-sectional side view of the tapered channel of Figure 22, having the first amount of anchoring material deposited thereon and additionally having a second amount of anchoring material deposited within the channel and also having a layer of high density polyethylene formed on the inner surface of the tube and attached to the second amount of anchoring material; Figure 24 is a perspective view of an apparatus for forming the metal tube while simultaneously applying both the integral coating to the inner surface thereof and the formation of the anchor within the channel thereof; Figure 25 is an enlarged perspective view of the extruder for applying the inner liner and the extruder to form the anchor of Figure 24; Figure 26 is an enlarged perspective view of the coating extruder and the anchor extruder of Figures 24 and 25; and Figure 27 is an elongated cross-sectional side view of a tapered channel having an anchor extruded directly therein and also having the integral coating formed on the inner surface of the tube.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY The detailed description set forth below in relation to the accompanying drawings is intended to be a description of the preferred embodiment of the invention up to now, and is not intended to represent the only way in which the present invention can be instructed or utilized. The description sets forth the functions and sequence of steps for constructing and using the invention in relation to the illustrated modes. It should be understood, however, that they are equivalent functions and sequences can be effected by different modalities that are also intended to be included within the spirit and scope of the invention. Although not by way of limitation, the process and apparatus of the present invention is well suited for use on the spirally wound flanged metal tube such as that described in US Patent No. 4,838,317 issued to Andre et al. and assigned to the beneficiary of the present W. E. Hall Co. In this regard the process and apparatus of the present invention will be described in relation to the manufacture of such a metal tube flanged in spiral helical form. However, those skilled in the art will recognize that the teachings of this invention are applicable to other metal tube structures as well as to other metal sheet products that are desired to resist corrosive environments. Referring now to Figures 1 and 2, the improved tube of the present invention generally described is comprised of a metal tube, preferably steel, spirally flanged, having externally extending flanges 12 formed therein, seams engaged 14, and an integrally formed polyethylene liner 16. The voids 18 are preferably formed between the liner 16 and the rolled steel 11 of which the tube 10 is formed as will be explained in more detail below. Referring now to Figure 3, there is provided an overview of the process of forming the metal tube 10 with an integrally formed coating 16 of the present invention. The process generally comprises pretreating a rolled metal such as steel so that it has a thin coextruded polymer layer formed therein and winding it for further fabrication. The pretreated rolled metal 11 is then unwound via an uncoiler 20, and the ridges and / or corrugations and seams 14 (as shown in Figures 1 and 2) are formed on it with a stamped profile former 22 (as shown in FIG. Figure 4). Subsequently, the preformed and preformed laminated metal 11 can be cleaned and heated 24. A sheet extruder and laminator 26 provides hot extruded polymer preferably high density polyethylene to the upper surface of the rolled metal. The laminator processes the hot extrudate in contact with the upper pretreated surface of the laminated metal, thermally bonding the coextruded film layer thereto. The tube and the coating are then cooled 28 before being received by the winding apparatus and the tube former 30, which forms the flat rolled metal in a helical tube section and bends the seams 14 together to form a water tight seal . A cutter 36 then cuts sections of tube to a desired length. The steps of forming the ridges 12 and the seams 14 with shaped profiled forming 22 and forming the flat rolled metal into a section of helical tube with the tube former 30 are described extensively in US Pat. No. 4,838,317, issued to Andre et al., The description of which is expressly incorporated herein by reference. However, other conventional metal tube making techniques as well as other fabricated metal products were also contemplated here. As best shown in Figures 1 and 2, the metal tube 10 of the present invention having an integrally formed coating includes a grooved wall defining a plurality of outwardly projecting structural flanges 12 and a hydraulically efficient inner surface. The flanges 12 are preferably formed in a helical configuration and the channels 14, which are formed inside it are generally formed having either a square or generally rectangular cross section and are open along the inner surface of the tube. Referring now to Figure 9, the detailed steps of the pretreatment process 19 used prior to the formation of the laminated metal 11 in sections of pipe 10 are described. Those skilled in the art will recognize that rolled metal is made in elongated lengths that are rolled up. to facilitate the subsequent training process.

The initial pretreatment process 19 is initiated by a prewash 62 which is carried out on the rolled metal typically a galvanized sheet metal to remove any oil and / or dust residue from the upper and preferably lower surface of the rolled metal 11. This step may consist of of processes well known in the art such as the application of a detergent, brushing with roller brushes, and rinsing with water. The rolled metal 11 is then subjected to an alkaline bath 64 to loosen and remove the chromates formed on the surface thereof. The alkaline bath 64 is followed by a rinse 66, which may be comprised of a buffer or neutralizing acid. The alkaline bath 65 and the rinse 66 are preferably repeated 68 and 70 to ensure proper removal of the chromates. After the alkaline baths 64 and 68 and the rinses 66 and 70, the rolled metal is subsequently subjected to a chemical attack such as a Parker Bonderite 1303 attack solution to roughen its surface and prepare it for the application of a coating or coat of primer The rolled steel is then dried 74 and the primer coating 76 can be applied thereto. The primer coating preferably comprises a thin layer (approximately 25.4 to 50.8 microns (1 to 2 mils)) of ethylene acrylic acid, to which the etched surface of the laminated metal 11 was applied. Optionally, after application, it can a primer coating 76 such as an adhesive and heat curing to securely bond the primer coating 76 to the etched surface of the laminated metal 11 is applied. In most cases, however, the primer coating 76 may be removed as indicated in the shaded lines in Figure 9. Subsequently, such attacked laminate 11 is heated 78 to approximately 204.4 ° C (400 ° F) and a relatively thin, continuous, flat coextruded polymer layer is applied to the rolled metal 11. As best shown in Figure 10, the co-extruded polymer layer is preferably formed having a thickness of approximately 254 microns (10 mils of p ulgada) and is formed having a lower laminating layer 81 and an upper laminating layer 82. In the preferred embodiment, the lower laminating layer 81 is formed of an ethylene acrylic acid comprising an adhesive that securely bonds the co-extruded laminate. 80 to the laminated metal 11 via direct contact with the laminated metal 11 or contact with the primer coating 76 applied to the rolled metal 11. The top laminate layer 82 is preferably composed of a polymer / ethylene acrylic acid blend having a concentration of between 70% and 98% of ethylene acrylic acid and 2% to 30% of polymer such as an olefin, which is crosslinked with the polyethylene coating to be finally applied to the sheet 11. As will be explained in more detail below , the co-extruded layer 80 therefore provides a lower adhesive layer 81 adapted to securely join the co-extruded layer 80 to the laminated metal 11 and an upper layer which can be applied to the laminated metal. it contains polymer 82, which serves as a base material to allow thermal bonding of a backing layer containing polymer 82, which serves as a base material to allow thermal bonding of a subsequent polymer to the upper layer 82 of the layer coextruded 80. Although not by way of limitation, in the preferred embodiment, the co-extruded layer is one such as that manufactured by the Dow Chemical Company under the PRIMACORE DAF trademark. 624. In the preferred embodiment, the coextruded polymer layer 80 is applied to the rolled metal 11 at an elevated temperature of about 204.4 ° C (400 ° F) and is strongly compressed thereon by means of a conventional roller 83. Subsequently, the laminated metal 11 having the co-extruded polymer layer 80 applied thereto is cooled 84 and subsequently rewound 85 for later use in the tube manufacturing process. In the preferred embodiment it was contemplated that the pretreatment process is facilitated both on the upper and lower surfaces of the laminated metal 11 with the treatment of the lower surface providing additional corrosion protection for the floor side of the resulting pipe. Nevertheless, the lower side may alternatively be coated with conventional films such as epoxy for cosmetic purposes. Referring now to Figures 4 and 5, the process of forming the metal tube 10 with the integrally formed coating 16 of the present invention is illustrated. As shown, the pretreated rolled metal 11 is pre-positioned in a roll or coil 30 is mounted on a conventional uncoiler 20. The denser-roll 20 facilitates unwinding of the pre-treated rolled metal 11, which has the co-extruded polymer layer 80 placed on the surface superior of it. The pretreated rolled metal 11 passes through a stamped profile former 22 having a plurality of stamped profilers 32, which progressively form the ridges 12 (as shown in FIG.

Figure 1) and the stitching members of flange 54 and 56 (as shown in Figure 6) within the laminated metal 11. It should be noted that the formation of the flanges 12 comprises the main cold forming processes for the tube 10 and is provided on the pretreated sheet metal. As such, the substantial tensile and compressive forces exerted in the cold forming process are accommodated by the relatively thin coextruded polymer layer 80 without fracturing and / or being brazed. After the stamped profiler 22 comes out, the laminated metal 11 enters a cleaner / heater 24 which prepares the upper surface of the laminated metal 11 for the subsequent thermal bonding of the relatively thick polymer layer, preferably high density polyethylene. same. Preferably the cleaner / heater 24, which prepares the top surface of the laminated metal 11 for the subsequent thermal bonding of the relatively thick polymer layer, preferably high density polyethylene thereto. Preferably the cleaner / heater 24 raises the temperature of the rolled metal 11 and the co-extruded polymer layer 80 placed thereon approximately 37.78-204.4 ° C (100-400 ° F) and does not exceed 82.22 ° C (180 ° F) of so that the substantially applied polyethylene layer at the end will bond more thermally and more easily to it. A conventional plastic sheet extruder 26 having a screw assembly 34, an extrusion head 36, and a laminator 38 is preferably used to apply a relatively thick layer of polymer, preferably a high density polyethylene to preformed and preformed rolled metal 11. As is well known, the screw assembly 34 heats, plasticizes and feeds a quantity of high density polyethylene to the extruder head 6. The head of the extruder 36 forms the polyethylene in a continuous layer 40 which preferably has a thickness of about 1.27 to 3.175 millimeters (0.050 to 0.125 inches), which is applied to the upper surface of the co-extruded copolymer layer 80 placed on the rolled steel 11. In the preferred embodiment, the polyethylene layer 40 is extruded onto the polymer layer co-extruded 80 at a temperature of about 204.4 ° C (400 ° F). A roll of the laminator preferably comprises a cold roll 38 which subsequently compresses or braids the extruded polyethylene layer 40 in contact with the coextruded polymer layer 80 and the formed and clean laminated metal 11. Because the high density polyethylene layer 10 is applied to the upper surface of the pretreated sheet metal 11 at a high plasticizing temperature, a strong thermal bond is provided between the high density polyethylene layer 40 and the polymer constituents that exist in the upper layer 82 of the polymer layer co-extruded 80 placed on the rolled metal 11. As such, a thermal polymer to polymer bond is achieved, which securely fixes the high density polyethylene layer 40 to the preformed and preformed laminated metal 11. The resulting laminated metal 11 can then be further cooled by blowing or water before being formed into a helical tube section 46. After the application of the high density polyethylene layer 40 to the pre-treated laminated metal 11, the resulting metal / polyethylene sheet has a cross-sectional configuration described in Figure 6. As shown, the high density polyethylene layer 40 extends a contiguous orientation generally thermally bonded on the upper surface of the laminated metal 11 and preferably above the seam of the female flange 54 and the seam of the male flange 56 formed on the opposite flanges of the laminated metal 11. Additionally, to facilitate the upper hydraulics of the tube 10, the layer 40 preferably forms a bridge over the channel formed by the flange 12 of the laminated metal 11 forming the voids 18 that give a generally flat configuration to the high density polyethylene layer 40. Those skilled in the artHowever, they will recognize that the layer 40 can be alternatively compressed in the recesses 18 to make them generally continuous with the flanges 12 or alternatively the groups 18 can be filled with a polymeric material if desired during the rolling process. Subsequently, the thermally bonded metal / polyethylene sheet 40 is passed to a folding / forming roll 50 which coils and bends helically the seams of the male and female flange 56 and 54 in interlocking seams, which form the length of the resulting pipe 46. The action of the folding / forming roller 50 is described in Figure 7. As shown in Figure 7, the folding / forming rollers 50 bend the seam members of the adjacent edges 56 of rolled metal 44 together to force the male seaming members 56 in the female stitching member 54 of an adjacent turn as the rolled steel 44 is wound helically and then bending both the male seaming members 56 and the female 54 in laminate juxtaposition with the adjacent laminated steel 11 The folding action of the folding / forming rollers 50 causes the high density polyethylene sheet 40 to be moderately displaced, ie from the seams of the folded flange 56 and 54, thereby accumulating it, ie, forming portions of displaced polymer 59 adjacent to the crimped seam.

Since it does not affect the hydraulic efficiency of the interior of the tube 10, in the preferred embodiment, an additional roller 52 is provided, which extends outwardly beyond the crimped seam formed by the seams of the folded rim 56 and 54, which they cause the displaced polymer portions 59 to fold over forming a generally uniform configuration of the polymer 40 as shown in Figure 8. Subsequently, the polymer layer 40 can be cooled and subsequently cut to the desired lengths via the conventional band saw , abrasive wheel, plasma tube cutter or laser 48. As will be recognized, the resulting tube section 46 has a substantial structural strength typical of the conventional spiral flanged metal tube. In addition, as shown in Figure 10, the tube 10 includes a coating of substantially pure high density polyethylene formed integrally 16, having sufficient thickness (i.e. approximately 2.54 millimeters (0.100 inches)), which is capable of withstanding the corrosion caused by polluting acids found in sewer applications. Additionally, since the high density polyethylene liner 16 is integrally applied to the tube during the manufacturing process and thermally bonded to the layer of co-extruded polymer 8 adhered to the steel tube 11, the delamination, vesiculation or fracture of the polyethylene layer high density 16 was removed. In addition, after installation of the pipe 10 in sewer applications, the adjacent pipe sections can be easily contacted and joined at their interfaces using high density polyethylene staples which can be thermally loosened / bonded to the high density polyethylene liner fixed inside the tube. As a further embodiment of the present invention, it was contemplated that the application of the relatively thick polyethylene layer 40 may be applied to the preformed and pretreated rolled metal 42 after all the structural metal forming operations for the tube 10. This additional embodiment is illustrated by the shaded lines in Figure 3, wherein the sheet extruder and the laminator 26A and the subsequent cooling step are described in shaded lines and placed after the seam forming steps and the tube 30. The process for applying the high density polyethylene layer after all the tube forming processes have been completed in an identical manner to that described here above and has the additional advantage of avoiding any displacement of the high density polymer layer 4 due to the process of metal fabrication Referring now to FIGS. 1 to 18, the relatively thick layer of high density polymer can be further secured to the laminated metal substrate by capturing a preformed anchor within a tapered channel formed in the metal substrate and attached to the high polymer layer. density. The anchor is preferably comprised of a polymeric material such as high density polyethylene and may alternatively be comprised of a core of high density polyethylene substantially covered by low density polyethylene. Alternatively, the anchor may comprise a substantially hollow core so that it is compressible and can therefore be more easily inserted through the narrow opening of the tapered channel. The anchor is generally placed within the tapered channel after the coextruded layer has been applied and the channel has been completely formed. With particular reference to Figure Ia, a round anchor 104 is captured within a tapered channel 100. The anchor 104 is comprised of a compressible material if it has been forced through the narrow opening 106 of the tapered channel 100 after it has been applied. the high density polyethylene layer, relatively thick, 102 to the laminated metal surface 103. Thus, a portion 108 of the high density polyethylene channel 100 102 has been similarly forced into the tapered channel 100 and is captured therein by the anchor 104. In this manner, the high density polyethylene layer 102 has been further secured to the laminated metal surface 103 to mitigate the likelihood of delamination or blistering. With particular reference to Figure 11b, the anchor 104 may alternatively be comprised of an inner core of high density polyethylene 132 surrounded by the outer shell of linear low density polyethylene which is comparatively more compressible than the inner core of high density polyethylene. 132, thereby facilitating compression of the anchor 104 during its insertion through the narrow opening 106 of the tapered channel 100. With particular reference to Figure 11c, the anchor 104 may alternatively comprise a hollow or void core 130 to facilitate compression of it during the insertion process. With particular reference to Figure 12, the anchor 104 can be inserted into the tapered channel 100 before the application of the relatively thick high density polyethylene layer 102 to the laminated mental surface 103. The high density polyethylene layer 102 may be subsequently welded or adhesively bonded to the anchor 104 to form a joining region 110. Those skilled in the art will recognize various welding processes, eg, thermal or ultrasonic, are suitable and that various means of adhesive bonding of the anchor 104 to the high density polyethylene layer 102 are equally suitable. The use of the adhesive bond requires the application of the anchor bonding material 104 prior to the application of the relatively thick high density polyethylene layer 102 to the steel surface 103. The bonding or connection of the high density polyethylene layer 102 to the anchor 104 in this way further ensures the high density polyethylene layer 102 in place. With particular reference to Figure 13, the anchor 104 can be formed to have a polymer film 112, preferably polyethylene, substantially surrounding its surface so that the anchor 104 and the surrounding portion of the polyethylene film 112 can be inserted into it. tapered channel 100 and a portion 114 of the polymeric film 112 can extend through the narrow opening 106 of the tapered channel 100 so that the outer portion 114 of the polyethylene film 112 can be attached to the high density polyethylene layer, relatively thick, 102. With particular reference to Figure 14, the anchor 104 can be formed to have an integral external portion 118, preferably connected thereto and a neck portion 122. In this way, the anchor 104 can be forced through the narrow opening 106 of the tapered channel 100, so that the neck portion 122 extends through the narrow opening 106 and the outer portion Rna 118 remains positioned outside the tapered channel 100, so that the high density polyethylene layer 102 can be bonded thereto. Referring now to Figures 15-17, the alternative method of placing or depositing the anchor 104 within a tapered channel is illustrated. Instead of forcing the anchor 104 through the narrow opening 106 of the preformed tapered channel 100, as illustrated in FIGS. 14 to 14, the anchor 104 can be placed within the tapered channel 100 before complete formation thereof. With particular reference to Figure 15, before tightening the sides 126 of the tapered channel 100, the channel is initially formed with the cross-sectional configuration of a rectangle. With particular reference to Figure 16, the anchor 104 is positioned within the rectangular channel 124. The anchor 104 can be easily placed within the rectangular channel 124 without the need to compress the anchor 104 due to the large size of the opening 125 of the rectangular channel 124. In this way, a non-compressible anchor can be used to mitigate the likelihood that the core will be pushed inadvertently out of the channel. With particular reference to Figure 17, the posterior positioning of the anchor 104 within the rectangular channel 124, the sides 126 of the rectangular channel 124 are pressed together so that a narrow opening 106 is formed therebetween, thereby capturing the anchor 104 within of a tapered channel 100. By placing the anchor 104 within the channel before bending the sides 126 thereof, the step of forcing the anchor 104 through the narrow opening 106 of the tapered channel 100 is eliminated. After being deposited in this way within the tapered channel 100, the anchor 104 can be attached to a layer of high density polyethylene subsequently applied as described above. Referring now to Figure 18, an alternative method for capturing an anchor within a channel is illustrated. A non-tapered rectangular channel 124 receives an anchor of complementary shape 128. The anchor 128 is preferably comprised of a linear elastic material which has to maintain a straight configuration, so that when it is bent it attempts to return to a generally straight configuration. The anchor 128 thus has to push out against the innermost surface of the bottom 136 of the channel 124, so that it attempts to straighten itself. That is to say, that the anchor 128, when placed inside a channel 124 of a tube is configured as a helix that attempts to straighten out by pushing out against the tube. The anchor 128 is placed inside the channel 124 before the application of the relatively thick high density layer 102 to the surface of the rolled metal 103. After the application of the high density polyethylene layer 102 the high density polyethylene layer it is thermally bonded to the anchor 128 as described above. Referring now to Figures 19-23, the anchor 200 can alternatively be extruded directly into the channel 100, thereby forming both thermal and chemical bonds to the surface thereof. The anchor 200 can be formed to have a substantial portion thereof external to the channel 100 within the interior of the tube so that a greater surface area is provided for the joining of the high density polyethylene liner. Additionally, the anchor 200 can be extruded into the channel 100 via a plurality of separate extrusion passages, wherein a plurality of corresponding portions of the anchor are extruded separately into the channel. With particular reference to Figure 19, the anchor comprises a body portion 202 formed within the channel 100 and an upper portion 204 extending from the channel 100 and a short distance in any direction, ie, perpendicular to the channel 100, to along the length of the channel 100. In this way, a larger surface area is provided for attaching the high density polyethylene liner 16 to the anchor 200 at the interface 206 thereof. With particular reference to Figure 20, alternatively, the anchor 200 may be formed so as to have a domed or convex interface 208 for increasing the surface area thereof available for later attachment to the high density polyethylene liner 16. With particular reference to Figure 21, the anchor 200 can optionally comprise the wings 210 formed therein to extend from the body 202 of the anchor 200 from the channel 100 outwardly, i.e., perpendicular to the channel 100, a substantial distance and to run along the length of the channel 100. In this way, the surface area available for attachment to the high density polyethylene layer 16 at the interface 212 of the anchor 200 and the high density polyethylene layer 16 is substantially increased. Those skilled in the art will recognize that various other configurations for increasing the surface area for attaching the anchor 200 to the high density polyethylene layer 16 are equally suitable. With particular reference to Figure 22, the anchor may optionally be formed directly within the channel 100 via a multi-extrusion process wherein a first layer 220, for example, is first formed within the channel 100. Subsequently, one or more additional layers are formed on the first layer 220. With particular reference to Figure 23, after the formation of the layer 220 within the channel 100, a second layer 222 is formed, for example, over it to complete the formation of the anchor 200. The high density polyethylene layer is formed then on the inner surface of the tube to thermally bond to the second extrusion 222 of the anchor 200, as discussed above. Such multiple extrusions are preferably formed within a short period of another so that each extrusion is thermally bonded to the other. Such a multi-extrusion process is partially useful in those cases where the size of the channel 100 is such that the capacity of a single extruder to fill the channel with material is exceeded. Those skilled in the art will recognize several different numbers of extrusions can thus be suitable for several different extruder channels and configurations. The process of extruding the anchor 200 directly from the channel 100 preferably takes place after the step of bending the seam and forming the tube 30 (Figure 3). The direct extrusion of the anchor 200 in the channel 100 causes the channel 100 to be substantially filled by the anchor to provide a more secure mechanical and thermal bond between them, and also facilitates the thermal bonding of the anchor 200 to the high density polyethylene layer. 16 since both the anchor 200 and the high density polyethylene layer 200 are extruded simultaneously and are therefore both at elevated temperatures, so they are more conducive to thermal bonding. Alternatively, the anchor 200 and the high density polyethylene liner 16 can be formed simultaneously from a single extruder. Generally, such a single extruder could provide more extruded material in those areas where the channels 100 are formed and less material in the other parts so that a generally uniform layer of high density polyethylene defines the coating 16. That is, the extruder it provides greater flow to the channels 100 to accommodate the filling thereof. In any case, when the high density polyethylene layer is applied, pressure may optionally be used to ensure adequate bonding to the co-extruded polymer layer and anchoring. Referring now to Figures 24-26, a preferred apparatus for the formation of the extruded anchor is shown and for applying the high density polyethylene layer to produce the filled anchor structures described in Figure 19 to 23. It should be recognized that the strip The elongated laminated metal used to form the tube structure has been pretreated to include the co-extruded polymer layer thereon and has been preformed to include the necessary channels and the previously described beaded profile. The apparatus functions to form the wall structure of the tube and simultaneously both forms an anchor within a channel formed in the tube and applies a coating to the inner part of the tube so that the anchor is attached to it. With particular reference to Figure 24, the apparatus preferably comprises a hopper 300 containing a granular polymer, preferably polyethylene 302. A lead screw assembly 304 extends from the bottom of the hopper 300 and into the interior of the tube 46 which is formed by the bending roll 306. As will be recognized, the elongated rolled metal is fed below the roll 306, which forms the elongated rolled metal in a circular section and bends the adjacent circular sections together to form the pipe 46. Those skilled in the art will appreciate that one or more such rollers may be used and that the single roller illustration 306 is schematic and in a simplified illustration only. As the rolled metal is bent by the roller 306 the resulting tube extends axially from the roller 306, that is, from left to right as seen in Figure 24. As in contemporary extrusion systems, a feed screw 308 heats and plasticizes the granular polymer 302 as it travels along the lead screw assembly 304. The feed screw assembly 304 transports the polymer 302 to an extrusion head assembly 310 located axially below the line of the bending roll 306, both of which form an anchor 200 (Figure 27) within a channel 100. of the pipe section 46 and apply a coating 16 to the inner surface thereof. With particular reference to Figures 25 and 26 the extrusion assembly 310 comprises an anchor extruder 312 and a coating extruder 314. The anchor extruder 312 deposits an amount of polymeric material directly into the channel 100, so that the channel 100 it is substantially filled with the polymeric material, thereby forming an anchor 200 directly therein. Because the interior of the channel 100 has the co-extruded layer previously applied thereto, the amount of polymer is firmly attached to the polymeric constituent of the co-extruded layer. The coating extruder 314 subsequently places a sheet of polymeric material on the anchor 200 as well as on the inside of the tube wall, so that the hot polymer material of the anchor 200 and the hot polymeric material of the coating 16 adhere to each other, as well as the coextruded layer on the wall of the tube. Preferably, each newly added coating section 16 is slightly over the previously applied layer thereof, to ensure adequate bonding thereto as well as the desired coverage of the interior of the tube 46. As can be seen from Figure 26, a roller 316 is preferably used to firmly press the extruded sheet of polymeric material in contact with the inner surface of the tube 46, thereby ensuring adequate contact pressure for the attachment of the layer 16 to the coextruded layer of the tube wall .

It has been found that the roller 316 comprised of aluminum and cooled with air allows the coating 16 to be pressed or compressed firmly in place while inhibiting the adhesion of the coating 16 to the roller 316 as well. The roller 316 is preferably adjustable opening to vary the thickness of the coating 16 applied to the interior of the tube section 46, as well as the application of pressure. Referring now to Figure 27, a cross section of an anchor 200 formed within the channel 100 and a liner 16 formed on the inside of a tube section 46 is provided. The anchor 200 is attached to the liner 16 at the interface 320 thereof. . Additionally, the anchor 200 is both captured and mechanically bonded to the co-extruded layer within the channel 100. The anchor 200 is joined within the channel 100 since it is applied to it while it is molten and thus joins the co-extruded layer within the channel 100. The anchor 200 is mechanically captured within the channel 100 due to the deltoid or tapering construction thereof, which mechanically prevents the anchor from being pushed therefrom. Additionally, the liner 16 is adhesively bonded to the coextruded layer formed inside the tube 46, since it is equally hot or cast.

In addition, the helical shape of the anchor by itself tends to prevent it from being pushed from the channel, since such thrust from the channel could require the helical anchor to be twisted to facilitate its removal. As such, the anchor is extremely resistant to channel and liner removal. It should be understood that the exemplary steel tube with the integrally formed coating described herein and shown in the drawings represents only one embodiment of the invention so far preferred. In fact, various modifications and additions to such an embodiment can be made without departing from the spirit and scope of the invention. For example, various polymeric materials having properties similar to high density polyethylene and ethylene acrylic acid can be used. In this regard, the applicant has additionally found that the low density polyethylene coating is a preferred candidate material for the coating 16 and the use of such material is clearly contemplated herein. The description and scope of the present invention is not limited to the use of high density polyethylene. In this regard, in the broad sense, the present invention facilitates the use of a relatively thick polymeric coating to be placed on a metal surface, which polymer adheres to the metal surface by means of a co-extruded layer having an adhesive component. lowermost and a more superior polymer / adhesive component, which allows the subsequent thermal bonding of the substantially coarse, substantially pure similar polymer layer, via the constituent polymer layer found in the uppermost layer of the coextruded layer. Additionally, the present invention contemplates the use for fixing a protective polymeric layer to a product manufactured after the pre-forming and / or completely forming the manufactured product by pre-treating the metal used in the manufactured product for the subsequent placement of the polymeric layer in the same. Also, various metals and alloys having sufficient structural strength can be used as pipe metal. In addition, the polymer laminated metal and the method for forming same are not limited to tube making, but may find application in a wide variety of areas such as laminated metal applications of automotive bodies and the like. Additionally, the anchors 104 need not be round as described and illustrated, but may have any shape and configuration, where they can be formed through a narrow opening of the tapered channel and subsequently expanded to remain captured therein. As well, the tapered channels 100 do not need to be generally triangular in shape, but can be of any suitable shape and configuration to capture the anchor therein and be compatible with their use in a metal tube or other laminated metal structure. Thus, these and other modifications and additions may be obvious to those skilled in the art and may be implemented to adapt the present invention for use in a variety of different applications. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (30)

1. A method for forming a metal tube laminated with polymer, characterized in that it comprises the steps of: (a) providing the rolled steel having a layer of co-extruded polymer formed on at least one surface thereof; (b) passing the rolled steel through a shaped profile former to form channels and seam members therein; (c) forming the rolled steel in a tube section; and (d) placing a hot-melt polyethylene coating in layered juxtaposition to the co-extruded polymer layer of a polyethylene / ethylene acrylic acid mixture formed on the rolled steel after the step of forming the rolled steel in a tube section.

2. The method in accordance with the claim 1, characterized in that the step of providing a laminated steel having a co-extruded polymer layer comprises providing the laminated steel having a coextruded polymer layer of ethylene acrylic acid and a polyethylene / ethylene acrylic acid mixture.

3. The method according to claim 2, characterized in that it comprises the step of applying pressure to the polyethylene layer to cause the polyethylene of the co-extruded polymer layer to bond to the polyethylene of the coating to thereby securely join the coating to the polyethylene. laminated steel

4. The method according to claim 1, characterized in that it further comprises the step of forming an anchor within at least one of the channels before the step of placing the coating on the sheet so that the linear coating is thermally bonded to the anchor.

5. The method according to claim 4, characterized in that the step of forming the anchor within at least one of the channels comprises extruding the anchor within at least one of the channels.

6. The method according to claim 5, characterized in that the step of extruding the anchor within at least one of the channels comprises extruding a plurality of anchoring portions within the channel via a plurality of corresponding extruders.

7. The method according to claim 5, characterized in that the step of extruding a plurality of portions of the anchor within the channel via a plurality of extruders comprises forming two portions of the anchor within the channel via two extruders.

8. The method according to claim 4, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having a portion thereof extending from the channels.

9. The method according to claim 4, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having two wings extending from the channels, the wings being formed along the channels and a contact with the co-extruded polymer layer to form a region of increased surface area to facilitate attachment of the anchor to the coating.

10. The method according to claim 4, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having a domed surface extending from the channels to form an increased surface area region to facilitate the union of the anchor to the coating.

11. The method according to claim 1, characterized in that the step of placing a coating in layered juxtaposition to the co-extruded polymer layer comprises simultaneously placing a layered juxtaposition coating to the co-extruded polymer layer and forming an anchor within at least one of the channels via a common extruder.

12. The method according to claim 11, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises, simultaneously placing a coating in laminate juxtaposition to the co-extruded polymer layer and form an anchor within at least one of the channels via a common extruder configured to provide more material where the anchors are to be formed.

13. The method according to claim 11, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises, simultaneously placing a coating in laminate juxtaposition to the coextruded polymer layer and form an anchor within at least one of the channels via a common extruder having separate extrusion heads to form the anchor and the liner.

14. The method according to claim 11, characterized in that it comprises the step of compressing or pressing the coating against the layer of coextruded polymer with an aluminum roll cooled with air to ensure adequate contact with it.

15. A method for forming a metal tube laminated with polymer, characterized in that it comprises the steps of: (a) providing the laminated steel having a layer of co-extruded polymer applied on at least one surface thereof; (b) passing the rolled steel through a shaped profile former to form channels and seam members therein; (c) Form an anchor within at least one of the channels; (d) placing a hot polyethylene coating in layered juxtaposition to the coextruded polymer layer of a polyethylene / ethylene acrylic acid mixture formed on the rolled steel; (e) apply pressure to the polyethylene layer to make the jolyethylene layer thermally bonded to the anchor and the coextruded polymer layer of the polyethylene / ethylene acrylic acid blend, the polyethylene of the coextruded polymer layer binds to the polyethylene of the coating to securely attach the coating to the laminated steel; and (f) forming the rolled steel in a tube section.

16. The method according to claim 15, characterized in that the step of applying pressure to the polyethylene layer comprises compressing or pressing the polyethylene layer against the coextruded polymer layer with an air-cooled aluminum roller.

17. The method according to claim 15, characterized in that the step of forming the anchor within at least one of the channels comprises extruding the anchor within at least one of the channels.

18. The method according to claim 17, characterized in that the step of extruding the anchor within at least one of the channels comprises extruding a plurality of anchoring portions within the channel via a plurality of corresponding extruders.

19. The method according to claim 18, characterized in that the step of exuding a plurality of portions of the anchor within the channel via a plurality of extruders comprises forming two portions of the anchor within the channel via two extruders.

20. The method according to claim 19, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having a portion thereof extending from the channels.

21. The method according to claim 20, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having wings extending from the channels, the wings are formed along the channels and in contact with the coextruded polymer layer to thermally bond thereto and to form a region of increased surface area to facilitate bonding of the anchor to the coating.

22. The method according to claim 21, characterized in that the step of forming an anchor within at least one of the channels comprises forming an anchor having a cambered surface extending from the channels to form a region of increased surface area to facilitate the connection of the anchor to the coating.

23. The method according to claim 22, characterized in that the step of placing a layered juxtaposition coating to the co-extruded polymer layer comprises simultaneously placing a layered juxtaposition coating to the co-extruded polymer layer and forming an anchor within at least one of the coextruded polymer layers. the channels via a common extruder.

24. The method according to claim 23, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises simultaneously placing a coating in juxtaposition laminate to the coextruded polymer layer and form an anchor within at least one of the channels via a common extruder configured to provide more material in which the anchors are to be formed.

25. The method according to claim 23, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises simultaneously placing a coating in juxtaposition laminate to the co-extruded polymer layer and form an anchor within at least one of the channels via a common extruder having separate extruder die openings to form the anchor and the liner.

26. A method for forming a metal tube laminated with polymer, characterized in that it comprises the steps of: (a) providing the laminated steel having a layer of co-extruded polymer applied on at least one surface thereof; (b) passing the rolled steel through a shaped profile former to form channels and seam members therein; (c) simultaneously placing a hot polyethylene coating in layered juxtaposition to the co-extruded polymer layer of a polyethylene / ethylene acrylic acid blend formed on the laminated steel and forming an anchor within the channel; and (d) forming the rolled steel in a tube section.

27. The method according to claim 26, characterized in that the step of placing a layered juxtaposition coating to the co-extruded polymer layer comprises simultaneously placing a layered juxtaposition coating to the coextruded polymer layer and forming an anchor within at least one of the coextruded polymer layers. the channels via a common extruder.

28. The method according to claim 27, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises simultaneously placing a coating in juxtaposition laminate to the co-extruded polymer layer and form an anchor within at least one of the channels via a common extruder configured to provide material in which the anchors are to be formed.

29. The method according to claim 27, characterized in that the step of simultaneously placing a coating in layered juxtaposition to the coextruded polymer layer and forming an anchor within at least one of the channels via a common extruder comprises simultaneously placing a coating in juxtaposition laminate to the co-extruded polymer layer and form an anchor within at least one of the channels via a common extruder having separate extruder die openings to form the anchor and the liner.

30. The method according to claim 26, characterized in that it comprises the step of compressing or pressing the coating against the coextruded polymer layer with an aluminum roll cooled with air to ensure adequate contact with it. MANUFACTURE OF STEEL PIPE WITH COVERING INTEGRALLY FORMED SUMMARY OF THE INVENTION A metal tube (46) and a method of forming the same with an integrally formed coating for use in corrosive and abrasive environments is described. The coating is comprised of a relatively thick polyethylene (40), which is thermally bonded to the metal tube. An intermediate layer of coextruded polymer of ethylene acrylic acid and a mixture of polyethylene / ethylene acrylic acid was applied to the metal tube to facilitate thermal bonding. The intermediate layer was applied to the rolled metal (11) in a pretreatment process and before forming the patterned profiles of the rolled metal flanges. The coating was applied to provide a uniform surface which is resistant to corrosive and abrasive action in sanitary or sewer applications. Anchors may be formed for additional securing of the coating within the flanges.