The Study On The Effect Of Simulated Deep-sea Environment Conditions On Corrosion Behavior Of Pipeline Steel

Deep sea environment is a complex environment with high hydrostatic pressure and low temperature(about 3?),salinity,velocity,the existence of oxygen,bacteria and other factors.It requires that the anti-corrosion performance of materials in long-term service in the deep sea environment is much higher than that in the land and shallow sea environment.At the same time,the rich resources of the deep-sea environment have gradually become the goal of human development with the shortage of energy resources.However,the current understanding of the corrosion of metal materials in the deep sea environment is still not comprehensive and profound.It is necessary to research the corrosion behavior of pipeline steel in the deep sea environment.In this paper,electrochemical method and surface characterization method are used,mainly including electrochemical noise,electrochemical impedance spectroscopy,potentiodynamic polarization curves and Raman spectroscopy and other test means.The action mechanism of stress,temperature and hydrostatic pressure on corrosion behavior of X65 pipeline steel,as well as the corrosion behavior of X65 steel coated with epoxy coating and corrosion behavior of X65 steel added with commercial corrosion inhibitor in saturated carbon dioxide environment were studied under the simulated deep-water environment.The conclusions are as follows:With the increase of hydrostatic pressure,temperature and stress,the charge transfer resistance shows a decreasing trend and the self-corrosion current density increases.The increase of hydrostatic pressure,temperature and stress increases the corrosion tendency of X65 pipeline steel.The X65 steel corrosion reaction is an activation process in the deep sea environment.The stress has little effect on the anode reaction process,but mainly promotes the cathode reaction.The corrosion reaction is mainly controlled by the anodic reaction process from 5 ? to 35 ?,and it is mainly controlled by cathodic process under-5 ?.The temperature changes the X65 steel corrosion types.The corrosion types of X65 pipeline steel types changes from local corrosion to uniform corrosion from 5 ? to 25 ?.No matter in the atmospheric pressure saturated carbon dioxide environment or saturated carbon dioxide in the deep sea environment,the anti-corrosion property of 1# inhibitor is the best and anti-corrosion property of 709 F inhibitor is relatively insufficient ideal among the four commercial corrosion inhibitors.They are the anode corrosion inhibitor.The hydrostatic pressure has different effects on different commercial corrosion inhibitor.No matter at atmospheric pressure or high hydrostatic pressure,the capacitance of epoxy coating increases with time,which shows that the corrosion resistance of the two kinds of epoxy coatings decreases with the passage of time.Hydrostatic pressure accelerates the failure behavior of modified epoxy coating,but inhibits the failure process of FM801 epoxy coating.The FM801 epoxy coating is of good proper protection performance in the deep sea environment,which is more suitable for the deep sea environment.