Typical Soil Crevice Corrosion Mechanism Of X100Pipeline Steel

Soil corrosion of pipeline steel is inevitable, especially the crevice corrosion damageto the buried pipeline steel is particularly serious. Crevice corrosion is mainly caused byseam in narrow space inside and outside of oxygen concentration and chloride ionmigration, chloride ion mass migration in the crack damage within the seam metalpassivation state, gap within the occluded cell formation, seam and ongoing within theautocatalytic effect, make the serious corrosion of metal. Gap device simulation is appliedin this article, the experiment selected the jiangxi yingtan, korla, xinjiang, Inner Mongolia’representative of acid, alkali, neutral soil simulation solution as a corrosive medium, X100pipeline steel was studied in the simulating crack crevice corrosion behavior, and studiedthe impressed current cathodic protection of crevice corrosion and the effect of explorationin acid and alkali neutral soil under simulation environment, the crevice corrosion law ofX100pipeline steel.Experiment studied the X100pipeline steel in simulated jiangxi yingtan, korla,xinjiang, Inner Mongolia ’the crevice corrosion behavior under the soilsolution.Experimental results show that the X100pipeline steel simulation crack sample inyingtan, korla,’soil simulation solution under medium, seam in Cl-concentration increaseswith the extension of time, and Cl-concentration increases rapidly at the beginning ofimmersion, soaking time after more than20h Cl-concentration increases more slowly.X100pipeline steel in yingtan simulated soil solution, the korla soil simulation solution,’soil simulation solution under medium, with the extension of soaking time, each locationin the seam of electrode potential E to some extent; And electrode potential E from seam toseam bottom gradually reduce, seam ascend a corrosion is most serious.X100pipeline steel was studied in aperture internal cathodic polarizationcharacteristic, studied the polarization time, seam cathodic control potential, factors suchas different media within the seam on the influence of polarization potential, and analyzedunder the condition of the cathodic protection of X100pipeline steel under three kinds of medium degree of crevice corrosion. Simulation results show that the X100pipeline steelslit specimen, in yingtan, korla,’soil simulation solution under medium, pass into the seam-1000MVCS polarization voltage, with the extension of the polarization time of eachlocation in the seam of polarization potential gradient descent trend; Polarization in thesame time, the seam to seam at the bottom of the increase of polarization potential gradientcertain trend, and with the polarization of the extension of time, the seam to the bottom ofthe seam less change of polarization potential gradient; X100pipeline steel simulationcrack sample in yingtan, korla,’soil simulation solution under medium, with the reductionof seam control potential seam polarization potentials of each location are present within acertain gradient of negative shift phenomenon; When the polarization potential-mvcsemvcse,1000-1000, each location in the seam polarized electrode are below the criticalvoltage protection, cathodic protection effect; When the voltage of seam-850mvcse,yingtan simulated soil solution under medium, seam deep in the bottom of anunder-voltage protection state.