含内腐蚀的船舶海水管道换管周期预测

Prediction of the replacement cycle of sea water pipeline with internal corrosion

文章针对船舶冷却系统的海水管道的主要失效原因——电化学腐蚀,以冷却系统中海水管道为研究对象,利用ANSYS软件分析了流速、腐蚀区域尺寸对含有电化学腐蚀的海水管道的剩余强度的影响,利用Origin得到各影响因素与最大等效应力的关系曲线图,计算了管道在各腐蚀深度下的失效压力,并选取经验公式对管道的剩余寿命进行预测,为管道的换管周期的确定提供一定的依据。结果表明,腐蚀深度和轴向长度对管道剩余强度的影响效果较为明显,在腐蚀深度达到管壁壁厚的40%时以及腐蚀轴向长度达到3.5 cm时,管道的等效应力变化速率非常快,因此,在对管道的日常检测维护中,应着重注意腐蚀的深度和轴向发展,以确保管道的正常运行,使船舶冷却水系统正常换热,从而保障船舶动力系统的正常运行。

In view of the present situation of the electrochemical internal corrosion monitoring of the seawater pipeline is difficult to control, combined the working environment of seawater pipe to do the prediction of the residual life of oil pipeline with corrosion. Then the influence of velocity and corrosion size on the maximum equivalent stress at the corrosion defect of pipeline was analyzed by ANSYS finite element method, the relationship curves between the influence factors and the maximum equivalent stress were obtained by using Origin, the failure pressure of the pipeline under different corrosion depth was calculated, and the remaining life prediction of the polar pipeline containing corrosion defects was carried out, which provides certain basis for the determination of pipe replacement cycle. Results show that the changes of the velocity and corrosion size do have a great impact on the equivalent stress of pipeline, especially when the corrosion depth reaches 40% of the wall thickness and the corrosion axis length reaches 3.5 cm, the change rate of the equivalent stress of pipeline is fast. Therefore, in the daily inspec- tion and maintenance of pipelines, we should pay attention to the depth and axial development of corrosion, so as to ensure the normal operation of the pipeline and make the ship＇s cooling water system normally heat transfer, so as to ensure the normal operation of the marine power system.