川西地区天然气管线内腐蚀机理研究及防护措施

Internal Corrosion Mechanism and Protective Measures of Natural Gas Pipelines in Western Sichuang

油气管线内腐蚀一直是制约油气管道安全运行的关键因素之一。通过调研川西地区某天然气管线基础运行状况,得到天然气含量、清管产物中总硫含量,判断出易发生内腐蚀的关键管段。基于电化学原理,对X80管材钢进行了电化学腐蚀实验,研究Cl^-、SO_4^(2-)对钢内腐蚀行为的影响,得出Cl^-和SO_4^(2-)共存时,两者的协同作用会显著加快钢的腐蚀速率。测定了管线运行环境下X80钢的平均腐蚀速率为0.59 mm/a,利用SEM和EDS分析了腐蚀产物膜,其致密性和均匀性较差且外层组织易脱落,最终确定出了该管线的内腐蚀产物主要为FeS及FeSO_4。针对该管线实际运行状况提出相应的防控措施,为管道安全运行提供参考。

Internal corrosion of oil and gas pipelines has been one of the key factors restricting the safe operation of oil and gas pipelines.By investigating the basic operating conditions of a natural gas pipeline in western Sichuang,the natural gas content and total sulfur content in pigging products are obtained,and the key pipe segments prone to internal corrosion are determined.Based on the electrochemical principle,the electrochemical corrosion test is conducted on steel pipe X80 to study the influence of Cl^-and SO4^2-on the internal corrosion behavior of steel.It is concluded that the synergistic effect of Cl^-and SO4^2-will significantly accelerate the steel corrosion rate when Cl^-and SO4^2-coexist.The average corrosion rate of X80 steel is determined to be 0.59 mm/a under pipeline operating conditions.The corrosion product membrane is analyzed by SEM and EDS,and its compactness and homogeneity are poor,and its overlying tissue is easy to fall off.Finally,the main corrosion products of the pipeline are FeS and FeSO4.The corresponding prevention and control measures are put forward according to the actual operation of the pipeline,which provides references for pipeline safe operation.