Importance

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Abstract

A metal pipe and method of forming the same with an integrally formed liner for use in corrosive and abrasive environment is disclosed. The liner is comprised of a relatively thick polyethylene which is thermally bonded to the metal pipe. An intermediate co-extruded polymer layer of ethylene acrylic acid and a polyethylene/ethylene acrylic acid blend is applied to the metal pipe to facilitate thermal bonding. The intermediate layer is applied to the sheet metal in a pre-treatment process prior to roll forming ribs into the sheet metal. The polyethylene liner is applied after the ribs are formed, preferably after the pipe has been formed, to provide a smooth, hydraulically efficient surface which is resistent to the corrosive action of sulfuric acid and the like encountered in sanitary applications, as well as abrasion caused by the flow of water-born debris such as dirt and gravel as is encountered in culvert applications. Anchors for further securing the polyethylene layer to the metal pipe surface are formed within the ribs, preferably by extruding the anchors directly therein. Such anchors preferably extend from the ribs so as to increase the surface area thereof available for attachment to the thick polyethylene layer. A multi-extrusion process may optionally be utilized to form the anchors.

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First Claim