ABSTRACT

This chapter describes stray current corrosion prevention. Stray currents are constituents flowing in the electrolyte from external sources. Any metallic structure buried in soil, such as a pipeline, represents a low-resistance current path and is therefore fundamentally vulnerable to the effects of stray currents. The current out of design or regulated circuit is called stray current. If stray current flows into buried metal and then from metal into earth or water, intensive corrosion will occur at the place where the current flows out. The electromagnetic effect refers to the physical phenomenon caused by alternating the electromagnetic field radiated by current-carrying, conductor-cutting metal pipeline. Induced voltage and current in pipeline is the function of current, frequency, operating methods, and other factors of the high-voltage lines. If the pipeline is buried in soil whose earth potential gradient changes greatly, the increase of the pipeline-earth potential caused is called earth electric field effect, mainly referring to coupling phenomenon caused by current in soil.