METHOD FOR JOINING METALLIC COATINGS OF CORROSION PROTECTIVE STEEL TUBE

摘要

PROBLEM TO BE SOLVED: To improve the sealability and to prevent advancement of the electrochemical corrosion by forming a coating layer with both the watertight sealability and insulation on either of or each of inside surfaces of an edge part of a corrosion resistant metallic sheet, and folding each edge part to join both edge parts in a hooking manner. ;SOLUTION: An intermediate resin layer 2 is formed as an impact buffer layer on a surface of a steel tube 1, and a strip-shaped corrosion resistant metallic sheet 3 is spirally coiled around its outer circumference. Both edges of the corrosion resistant metallic sheet 3 are joined in a hooking manner, and a coating layer with both the watertight sealability and insulation is formed on an inside surface of either edge. The edge on which a watertight insulation coating layer 4 is formed is outwardly folded, and the other edge adjacent thereto is inwardly double-folded. The folded edges are overlapped, and joined in a hooking manner by applying the force by a pressing means such as a roller with the folded position of the outwardly folded part as the supporting point.;COPYRIGHT: (C)1998,JPO