20#碳钢管道内沉积物对腐蚀行为的影响

 塔河油田地面原油集输金属管道主要材质为20^#碳钢。地面原油集输金属管道腐蚀主要为内壁点蚀，点蚀区域存在有沉积物。为研究沉积物对地面原油金属集输管道的腐蚀行为的影响，在对管道内壁沉积物类型分析的基础上，通过将无、有沉积物覆盖的20^#碳钢试片挂入高压釜来模拟现场腐蚀实验，应用失重法分析、电位极化曲线测试、丝束电极测试及扫描电镜技术对无沉积物覆盖的20^#碳钢试片及有沉积物覆盖下的20^#碳钢试片的腐蚀失重速度、腐蚀过程、腐蚀电位分布及扫描电镜特征进行测试。分析表明：无沉积物覆盖区20^#碳钢相比有沉积物覆盖腐蚀失重速度小；两者腐蚀过程均受阴极扩散控制，后者阳极过程受到促进，腐蚀电位降低、耐蚀性变差；前者腐蚀电位分布随时间变化不大，以全面腐蚀为主，后者腐蚀电位分布随时间变化大，点蚀特征明显，建立了无、有沉积物覆盖的20^#碳钢腐蚀行为影响过程模型。

Effects of Sediments on the Corrosion Behavior of 20# Carbon Steel Pipe

The main material of the crude oil gathering and transportation pipeline in Tahe oilfield is 20^# steel. The pipeline surface corrosion is mainly the wall pitting corrosion, with deposits in the pitting region. In order to study the corrosion behavior of sediments on the ground crude metal pipeline, based on the analysis on the sediment types on the inner wall of the pipeline, the cover of 20^# carbon steel specimen with or without sediments is hanged in the autoclave to simulate the scene corrosion experiment, using the weight loss method, the polarization curve test, the wire beam electrode test and the scanning electron microscopy. With 20^# carbon steel corrosion sediments under the coverage of the test piece, the weightlessness velocity, the corrosion process, the corrosion potential distribution and the SEM characteristics are determined, with no sediment covering the 20^# carbon steel specimen. It is shown that in the area of 20^# carbon steel without sediment covered, the corrosion weight loss rate is smaller than that with sediments covered; both corrosion processes are governed by the diffusion control, the latter by promoting the anodic process and reducing the corrosion potential and the corrosion resistance; the distribution of the corrosion potential does not change with time, the general corrosion, the corrosion potential distribution varies with time, with prominent pitting characteristics.