海洋平台海水系统铜镍合金管道腐蚀的原因分析

Corrosion causes of Cu-Ni alloy pipeline in seawater systgem of offshore platform

海上平台常取海水用作工艺冷却及平台消防,海水腐蚀性强,一旦造成管道腐蚀穿孔,将给人员、财产安全带来巨大威胁并造成生产关停等严重后果。基于海上平台海水系统常用的B10铜镍合金管道在渤海某平台发生腐蚀穿孔实例,通过一系列实验检测(化学分析、金相分析、电镜扫描、能谱分析),结合海水系统特性对腐蚀原因进行针对性分析。结果表明,管道腐蚀穿孔主要原因为海水含砂量较高冲刷破坏钝化膜,以及海水中电解质含量较高加速电化学腐蚀。建议调节平台上铜铝电解装置电解电流以降低电解质浓度,同时在海水系统中增加除砂装置以加强对海水中砂石的滤除效果。

Seawater is often used for process cooling and fire protection in offshore platforms.Seawater is highly corrosive.Once the pipeline is corroded and perforated,it will pose a huge threat to the safety of personnel and property and cause serious consequences such as production shutdown.Based on the instance of the corrosive perforation of B10 Cu-Ni alloy pipeline in the seawater system of a platform in Bohai Sea,a series of experimental tests were conducted,including chemical analysis,metallographic analysis,macroscopic scanning and energy spectrum analysis.The pertinent analysis was carried out associated with the analysis on the characteristics of the seawater system.The results show that the main causes of pipeline corrosion perforation are the erosion of passive film caused by high sand content in seawater and the accelerated electrochemical corrosion caused by high electrolyte content in seawater.It is suggested to adjust electrolytic current the electrolysis device on the platform for reducing electrolyte concentration and to add a sand renovel device for enhancing removal of sand and stone from seawater system.