某凝析油集输管线内腐蚀影响因素分析

Influence Factors of Inner-corrosion in a Condensate Oil Gathering and Transportation Pipeline

某凝析油集输管线投产后内腐蚀穿孔频繁发生,复杂的腐蚀影响因素导致难以制定有效的防腐措施。采用高压釜模拟管线内部腐蚀环境,结合光学显微镜、扫描电子显微镜和X射线衍射仪等对试样进行分析,以探讨微量硫化氢(H_(2)S)、二氧化碳(CO_(2))和氯离子(Cl^(-))对碳钢内腐蚀的影响规律。试验结果表明:该管线以CO_(2)腐蚀控制为主,腐蚀产物为FeCO_(3),既有均匀腐蚀又有局部腐蚀,微量H_(2)S和Cl^(-)的存在促进局部腐蚀的发生;H_(2)S含量由50 mg/L增加至100 mg/L时,平均腐蚀速率增加约30%,局部腐蚀坑尺寸显著增大;Cl^(-)浓度由69600 mg/L增加至120000 mg/L时,平均腐蚀速率未见明显变化,但局部腐蚀坑增多。

After a condensate oil gathering and transportation pipeline is put into operation,the internal corrosion perforation is frequent,so it is difficult to develop effective anti-corrosion measures due to complex corrosion influencing factors.In order to investigate the influence of trace hydrogen sulfide(H_(2)S),carbon dioxide(CO_(2))and chlorine ion(Cl^(-))on the corrosion of carbon steel,an autoclave was used to simulate the corrosion environment inside the pipeline,and the samples were analyzed by optical microscope,scanning electron microscope and X-ray diffraction.Results show that the pipeline damage is mainly controlled by CO_(2) corrosion,and the corrosion product is FeCO_(3),which has both uniform corrosion and local corrosion.The presence of trace H_(2)S and Cl^(-)promotes the occurrence of local corrosion.When H_(2)S content increases from 50 mg/L to 100 mg/L,the average corrosion rate increases by about_(3)0%,and the size of local corrosion pit increases significantly.When the concentration of Cl^(-)increases from 69600 mg/L to 120000 mg/L,the average corrosion rate does not change significantly,but the local corrosion pits increase.