多因素共同作用对Q235B钢管腐蚀行为的影响

Influence Factors of the Corrosion Behavior of Q235B Steel Pipeline

为探究油气管道中温度、流速和CO_2/H_2S分压协同作用下对钢管腐蚀行为的影响,对温度、流速和CO_2/H_2S分压比建立正交实验,通过SEM,XRD等分析技术探究不同改变量对Q235B管道腐蚀行为的影响。结果表明:在CO_2和H_2S共同影响下,70℃、流速为1. 5 m/s时,腐蚀动力学过程十分剧烈; H_2S的存在能够一定程度上抑制腐蚀,低含H_2S的腐蚀环境中,腐蚀为CO_2主导,在高温下内层形成良好的FeCO_3膜,腐蚀速率降低; H_2S通过形成FeS腐蚀产物层增加点蚀的程度;在H_2S和CO_2的组合存在下,凹坑的起始速率最高,CO_2能够协同促进,在同一时间内提供更多的实质性FeS膜;在点腐蚀演化过程中,CO_2和H_2S的协同作用在70℃时最为显著,同时流速在增大的过程中,会使FeS分布不均,而FeS的不均匀分布会诱导微电池作为该阶段在钢表面的点腐蚀的驱动力。研究结果对于制定石油管道防腐措施具有指导意义。

To investigate the influence of temperature, flow velocity and CO2 and H2S partial pressure ratio CO2/H2S partial pressure ratio on the corrosion behavior of oil and gas steel pipelines, orthogonal test of temperature, flow velocity and CO2/H2S partial pressure ratio was carried out. The SEM, XRD and other analytical techniques were used to explore the variables on the corrosion behavior of Q235B pipeline. The results show that under the combined influence of CO2 and H2S, the corrosion kinetics is very intense at 70 ℃ and the flow rate of 1.5 m/s . The presence of H 2S can inhibit corrosion to some extent. In a corrosive environment containing low H2S, the corrosion is dominated by CO2, and a good FeCO3 film is formed in the inner layer at a high temperature, and the corrosion rate is lowered. H2S increases the degree of pitting by forming a FeS corrosion product layer. In the presence of H 2S and CO2, the initial rate of pits is the highest. CO2 can synergistically provide more substantial FeS film. During the evolution of pitting corrosion, the synergistic effect of CO2 and H2S is most significant at 70 ℃. The increase of flow rate makes the FeS distribution uneven, and the resulted induced micro-cells become the driving force for pitting corrosion on steel surfaces as the stage. The research results could provide guidance for the development of anti-corrosion measures for petroleum pipelines.