埋地管道防腐涂层破裂时的钢材腐蚀模拟研究

Simulation Study on Steel Corrosion of Buried Pipeline When Anticorrosion Coating Is Broken

本文运用有限元模拟软件分析埋地管道在不同纵向应变和腐蚀缺陷深度下的腐蚀规律,探究在埋地环境下的腐蚀行为并给出腐蚀机理与建立CO2与O2腐蚀的协同作用模型。通过有限元模拟结果表明:随着纵向应变的逐渐增加,von Mises应力不断增大且向腐蚀缺陷中心集中,此时由于塑性变形导致阴极反应被加强,腐蚀电流密度也逐渐增大,在管壁与3PE防腐层交界处达到最大;随着腐蚀缺陷的逐渐加深,von Mises应力也不断增大并集中在整个缺陷方向,有向缺陷外延展的趋势,腐蚀电流密度分布不均匀,3PE防腐层与管壁交界处分布最集中,此处腐蚀最严重。

Finite element simulation software is used to analyze the corrosion laws of buried pipelines under different longitudinal strains and corrosion defect depths, explore the corrosion behavior in the buried environment, give the corrosion mechanism and establish the CO2 and O2 corrosion synergistic model. The results of finite element simulation show that the von Mises stress increases and focuses on the center of the corrosion defect with the increasing of the longitudinal strain. At the same time, the corrosion current density increases gradually due to the strengthening of the cathode due to the plastic deformation, and reaches the maximum at the junction between the tube wall and the 3PE coating. With the gradual deepening of the corrosion defects, von Mises stress increased and concentrated in the whole direction of the defects;with the trend of the extension of the defects, the distribution of corrosion current density is not uniform;and the junction of 3PE corrosion coating and pipe wall is the most concentrated, where the corrosion is the most serious.