THE CORROSION CAUSES OF URBAN BURIED STEEL-MADE GAS PIPELINE AND ITS ANTICORROSIVE COUNTERMEASURES

An excavating investigation of a buried pipeline carried out in a city of Southern China is discussed in this paper. The soil environment,the coating′s failure and surface corrosion forms and microcosmic components of the steel were detected and analyzed. It is shown that the soil along the pipeline was seriously corrosive mainly attributed to soil moisture content and stray current interference,moreover,the Cl- and SO2-4 could also accelerate the corrosion course. Inclusions especially the sulfide in the steel made the corrosion easier to occur and develop along the inclusion. The lack of CP also was one of the corrosion reasons that caused the pipeline′s failure. Keep the coating intact made an obvious effect to pipe′s anticorrosive protection. Some measures to solve corrosion problems are obtained in this paper.