Corrosion inhibition method

摘要

The present invention provides a corrosion inhibition method which minimizes environmental adverse effects by using phosphate base anticorrosives without using zinc salt base anticorrosives and by reducing the concentration of the phosphate base anticorrosives, enables stable formation of an effective initial protective film, and does not affect water treatment after the formation of the initial protective film. In an initial protective film formation process of forming an initial protective film on a surface of an iron-based metallic member of a water system by adding anticorrosives to the water system, at least one selected from a group consisting of pyrophosphoric acids and pyrophosphates is employed as the anticorrosives and the initial protective film formation process is conducted such that the initial pH at the start of the initial protective film formation process is adjusted to be 5 or more and less than 7 so that the pH at the end of the initial protective film formation process becomes 7 or more.