Study On Stress Corrosion And Protection Potential Optimization Of Buried Pipeline Under Stray Current

It is not uncommon for pipelines to be laid parallel to high-voltage transmission lines or High-speed rails due to the many restrictions on topography and landforms,which will cause serious stray current corrosion.In the southwest of China and other areas with frequent geological disasters,buried pipelines are often damaged by stress corrosion.Previous studies only considered the effect of stray current interference or stress corrosion on the pipeline,and rarely considered the common effect of the two.In this paper,a set of self-built corrosion measuring device was introduced to study the effect of AC/DC stray current and stress corrosion on pipeline steel and the effectiveness of protection potential in cathodic protection system.The effect of different types of stray current on pipeline steel corrosion was studied by corrosion measuring device.The corrosion morphology and corrosion rate of X80 steel with different interference current density were studied.Then,the effect of alternating current and stress corrosion on the corrosion of pipeline steel was studied by means of corrosion measuring device.Afterwards,the effect of cathodic protection system on stray current interference and stress corrosion was studied by means of corrosion measuring device.The results show that: when X80 steel is not damaged by stress corrosion,the degree of fluctuation of polarization curve increases with the increase of interference current density,and the corrosion rate also increases,and the corrosion of pipeline steel under DC interference state is more serious than that under AC interference.However,the polarization curve and corrosion rate of X80 steel samples are closely related to tensile strength when stress corrosion is present.In addition,the effective protection potential of the cathodic protection system isn’t a constant value,but is related to the presence of stray current,stress corrosion and other interference.In practice,the negative protection potential should be adjusted constantly to enhance the protection effect.