Study On Flow Induced Corrosion Of20Cr Steel In CO₂and Cl^-Coexistence Environment

In oil and gas production, High-speed flow often pass through the oil-well tubular andground manifold. These fluids flow generally contain Cl-,CO2and other components, evencontain solid particles. Compared to static media environment, the resulting corrosion(flow-induced corrosion) problems are more serious. This paper study experimentally aboutcommon usage ground manifold20Cr steel in different conditions of flow-induced corrosioncharacteristics.This paper study experimentally about the basic law and influence factors in containingCl-,CO2,CO2+Cl-etc corrosive environments by the jet experiment equipment. The corrosionrate was mainly measured by weight loss method. The surface topography and corrosionproducts are analyzed by scan electron microscopy.The results show that with the formation of corrosion product films of metal surfaces theFlow-induced corrosion rate will be gradually decreased. When the flow rate,attack angle,sandcontent is constant, corrosion rate will decline as a high speed when the erosion time exceed90minutes.The flow rate has a great impact on flow-induced corrosion rate, the corrosion rateincreases with velocity in the form of an exponential function. In the low velocity zone,corrosion rate is mainly controlled by electrochemical corrosion; In the moderate velocityzone, corrosion rate is mainly controlled by electrochemical corrosion and mechanical action,moreover, flow-induced corrosion gradually changes from electrochemical control tomechanical action control, in the high velocity zone, corrosion is mainly controlled by themechanical action.Flow induced corrosion rate will change with the attack angle. low attack angle corrosionrate is significantly higher than high attack angle corrosion rate. The interaction of shearingaction and normal force of the fluid reaches the max value when the attack angle is45°, andthe corrosion rate of flow induced corrosion reaches the max value.The content of solid particles has a great influence on flow induced corrosion, corrosionis most serious when the content of solid particles is25kg/m3, the particles are easy depositingwhen sand content exceed this value, and because of the solid particle collision caused"shielding effect", this effect made the erosion of material decreases, reducing the corrosionrate.