保温铝板表面变色原因分析及防护

Cause Analysis and Protection of Surface Discoloration of Thermal Insulation Aluminum Plate

铝合金具有较好的加工性能及耐蚀性能,且具有质量轻及强度高等优点,在各个领域被广泛应用。但在炼油化工装置使用过程中,腐蚀性介质的存在会造成铝合金发生腐蚀失效,给装置的发展造成严重的影响。中国石油某炼油三部罐区下雨后,保温铝板有部分颜色发黑发黄现象(距离安装完成约5天),给装置安全平稳运行造成严重影响。通过对保温铝板进行宏观及低倍分析、材质分析、扫描电镜及能谱分析、X射线衍射分析等检测发现:铝板的材质不是3003铝合金,而是纯铝1050,其表面变色的原因是因为发生了缝隙腐蚀,外部环境中的水汽及腐蚀性元素(Cl、S、O)是造成铝板发生缝隙腐蚀的主要因素。

Aluminum alloy has good machinability and corrosion resistance,and has the advantages of light weight and high strength,and is widely used in various fields.However,in the process of using the refinery chemical plant,the existence of corrosive media will cause corrosion failure of aluminum alloy,which has a serious impact on the development of the device.After the rain in the three tank farms of a refinery of petrochina,some of the aluminum insulation panels turned black and yellow(about 5 days from the completion of installation),which seriously affected the safe and stable operation of the device.Through the macro and low power analysis,material analysis,scanning electron microscopy and energy spectrum analysis,X-ray diffraction analysis of the thermal insulation aluminum plate,it was found that the material of the aluminum plate is not 3003 aluminum alloy,but pure aluminum 1050,the reason for the surface discolcolor is because of the gap corrosion,water vapor and corrosive elements in the external environment(Cl,S,O)are the main factors causing the gap corrosion of the aluminum plate.