X65钢注水海管介质含有溶解氧，导致管道内发生严重腐蚀。针对该问题，基于现场注水海管基础数据，考虑流速、温度、溶解氧浓度和Cl-浓度对X65钢腐蚀行为的影响，设计9组正交试验，采用高温高压反应釜、扫描电子显微镜和X射线衍射仪进行失重测试和腐蚀产物表征；结合多元线性回归法，建立腐蚀预测模型。结果表明：4种影响因素对腐蚀速率的影响程度由大到小排序为：溶解氧浓度>温度>流速>Cl-浓度，溶解氧浓度是腐蚀主控因素；随着流速、温度、溶解氧浓度和Cl-浓度的增大，腐蚀速率增大；腐蚀产物表征结果表明，腐蚀产物主要为Fe3O4和Fe2O3;考虑上述4个因素的影响，基于7组均匀腐蚀速率值，建立腐蚀预测模型；采用剩余2组均匀腐蚀速率值对腐蚀预测模型进行验证，误差最大为8.9%,表明该腐蚀速率预测模型的准确性较高。
The medium of X65 steel injection sea pipe contains dissolved oxygen, causing severe corrosion inside the pipeline. Regarding this issue, based on the basic data of the on-site water injection subsea pipeline, considering the effects of flow rate, temperature, dissolved oxygen and Cl- concentration on the corrosion behavior of X65 steel, 9 sets of orthogonal tests were designed, and the weight loss test and corrosion product characterization were carried out by using high temperature autoclave, scanning electron microscope and X-ray diffractometer. Combined with multiple linear regression method, a corrosion prediction model was established. Results showed that the order of the degree of influence of the four influencing factors on corrosion rate from large to small was: dissolved oxygen concentration > temperature > flow rate> Cl- concentration, and dissolved oxygen concentration was the main control factor of corrosion. The corrosion rate increased with the increases of flow rate, temperature, dissolved oxygen concentration and Cl- concentration. The characterization results of corrosion products showed that the corrosion products were mainly Fe3O4 and Fe2O3. Considering the influence of the above four factors, a corrosion prediction model was established based on seven groups of uniform corrosion rate values. Furthermore, the remaining two groups of uniform corrosion rate values were used to validate the corrosion prediction model, and the maximum error was 8.9%, indicating that the corrosion rate prediction model was accurate.
