長大パイプライン建設途上の電食防止について

抄録

The pipelines in Japan are commonly required to be constructed in several disorderly separated sections, wherever the right of way is applicable. Therefore, cathodic protection system against the stray-current corrosion of pipeline should be applied carefully. Through analyses of practical experiences, the following conclusions were obtained. (1) Stray-current control of pipelines is usually required not only after the completion of the construction but also during their construction on account of long construction schedule and required quality of each pipeline. (2) Temporary galvanic anodes may be generally used for maintaining proper protective effect against pipe corrosion, where the potential gradient in soil is not so steep. (3) When the potential gradient is very steep, ordinarily arranged galvanic anodes are not sufficient, and use of impressed current systems is preferable. (4) In introducing an automatic potential controlling system, several rectifiers would be necessary when different locations of a pipeline show negative coefficient of mutual potential change so as to control such potentials in a consistent manner.