| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing an internal coated steel pipe excellent in peeling resistance even under an environment where it contacts water that is preferable as a water pipe. SOLUTION: The method for manufacturing an internal coated steel pipe sequentially performs the step of forming a chemical treatment layer on the inside of a steel pipe using a phosphate series chemical treatment liquid, the step of forming a primer layer by coating a liquid where an epoxy resin and a curing agent are diluted with a solvent thereon, and the step of forming an internal coated layer by spraying a modified polyethylene-based resin powder thereon. The step of forming the internal coated layer should includes the step of heating the steel pipe at a temperature of 150°C or higher than Vicat temperature softening point of the resin, coats the modified polyethylene-based resin powder onto the steel, and then holds the steel at a temperature of 50°C or higher than Vicat temperature softening point of the resin for six minutes or longer. This allows waterproof to be significantly improved. COPYRIGHT: (C)2009,JPO&INPIT |
