Study On Chloride Ion Corrosion Behaviors Of Long-distance Pipeline

At present, the domestic oil pipeline are mainly composed of pipeline steel. Steelpipeline face the corrosive media in the service process and cause leakage failure, due tolong-term exposure to impurities in the crude. This not only causes huge economic losses, butalso causes serious environmental pollution, threatening the lives of the people. Therefore, itis necessary to study the internal corrosion behavior of buried pipeline.Based on the analysis of corrosion of buried long-distance pipeline transporting crude oil,this paper according to the status quo of the presence of chloride pipe wall corrosion, aspipeline of export station to the research object, using the polarization curves andelectrochemical impedance technology, studing on within the corrosion behaviors of thecurrently used three pipeline steel X70, X80and X100.The conclusion mainly concluds:(1) In the chloride ion concentration range of theexperiments, shows the trend of low concentrations promoting corrosion, high concentrationsinhibiting corrosion. When the chloride ion concentration is40mg/L, three kinds of pipelinesteel corrosion rate are the largest and corrosion is most serious. X70corrosion resistance isthe worst.(2) As the temperature increases, the corrosion potential of three kinds of pipelinedecreases as the temperature increases, and it close to the equilibrium potential of theanode,the corrosion reaction is controlled by the cathode. Within the higher temperaturerange, X100resistance to high temperature corrosion is the worst.(3) At the acidic etchingsolution of three kinds pipeline steel corrosion mechanism changed, mainly converted touniform corrosion by potting. In the experimental range of PH, X80shows good resistance toacid.(4) Immersed in simulated etching solution at different times, three kinds of pipelinesteel corrosion current density first increases and then decreases. X80shows better corrosionresistance.