A Study On The Performance Of Buired Pipeline Cathodic Protection Interfered By AC

For AC interference of buired pipelines，the traditional expeirence that AC interferencecan not cause seirous corrosion on buired pipelines，the hazards of AC is due to the faultcurrent. However，in recent years，with the discovery of cases of corrosion and in-depthresearch? The researchers have a deep understanding of the dangers of AC interference forbuired pipelines. AC interference corrosion is a relatively new phenomenon，and thecorrosion mechanism is not clear, therefore for AC interference corrosion research methodshave a certain degree of particularity and some diiffculties.The papers choose neutral solution for laboratory research of the pipeline corrosioninterfered by AC. By the corrosion potential、the corrosion current density andelectrochemical impedance spectroscopy (EIS) of X80steel interfered by AC to analyze thevairation of the steel electrochemical parameters, and to explore the mechanism of ACinterference corrosion and Research the laws of cathodic protection under the ACinterference. The results showed that when X80steel was interfered by certain AC itscorrosive potential was decrescent，its corrosive current was accrescent? and the corrosionrate increased.The AC interference effects the natural potential of buried pipeline, and the protectpotential、protection current density of cathodic protection system. This paper presents aneutral solution of carbon steel protection potential criterion when the AC interferencevoltage is1ow(<9Vcse)? optimal cathodic protection potential in-1.085V—1.221V (vs.CSE)range.Through the soil box expeirment, this paper study the different measurement methods inmeasuirng the protection potential. The results found that： When the polairzation level isweak (-0.850—1.050Vcse)、AC interference voltage is low (0~6Vcse)，the protect potentialchanges very little> and then with the increase of the voltage of the AC interference(7?15Vcse)，the protection potential measurement value prejudiced trend growing； Whenthe polarization level is strong (-1.100V?-1.500Vcse), the protection potential measuredvalues gradually more positive with the increase of the voltage of the AC interference, but themagnitude is not prejudiced great. This thesis identified the real protection potential measuirng method in the case of AC interference exists.