柴油加氢高压空冷器泄漏原因分析及改进措施

某石化公司2.2 Mt/a柴油加氢装置高压空冷器,在开工硫化过程中,在管束与管板焊接部位发生泄漏,从设计、制造、检验、安装、开工等方面进行了综合分析,结果表明:泄漏是由硫化物应力腐蚀开裂造成的。虽然高压空冷器管箱材质Q345R和管束材质20号钢具有较好的可焊性和良好的抗开裂性能,但是仍然存在局部焊缝硬度过高和残余应力较大等问题,在高浓度H 2S环境中,高压空冷器极容易发生硫化物应力腐蚀开裂。

Cause Analysis and Improvement Actions of Air Cooler Leakage in Diesel Hydrogenation Unit

During vulcanization of high-pressure air cooler in a 2.2 Mt/a diesel hydrogenation unit,leakage occurred at welding part between tube bundle and tube sheet.Comprehensive analysis was made from the aspects of design,manufacture,inspection,installation and start-up,which shows that it is caused by sulfide stress corrosion cracking.Although pipe material Q345R and tube bundle material No.20 steel have excellent weldability and crack resistance,there are still some weld joints with high hardness and residual stress,which is prone to accelerate hydrogen sulfide stress corrosion cracking under high concentration H 2S environment.