The Ⅱ^# atmospheric -vacuum distillation unit in SINOPEC Beijing Yanshan Petrochemical Co. Ltd was originally designed for processing Daqinig Crude. Carbon steel was selected for the equipment piping material without consideration of corrosion protection. When the unit began to process blended Daqing Crude, Russian Crude, Jidong Crude, the sulfur and acid value of blended Crude was increased from 0.1 to 0.27 and from 0. 04 mgKOH/g to 0.62 mgKOH/g respectively, the equipment corrosion deteriorated and the existing materials of equipment and piping could not meet the safe operation requirements. To improve the equipment corrosion resistance performance, the materials of equipment such as furnaces, tower vessels, heat exchangers, etc and piping for the service temperature of over 240 ℃ were upgraded for pr℃ essing crude oil with 0.5% of sulfur and 0.7 mgKOH/g of acid value. The study of data of crude oil properties and online corrosion monitoring before and after material upgrading show that the corrosion rate of piping of upgraded materials has been greatly reduced and corrosion resistance improvement is obvious, and material upgrading is practical in improvement of corrosion resistance performance.%常减压Ⅱ套蒸馏装置（Ⅱ套蒸馏装置）原设计加工大庆原油，设备管道均采取碳钢材质，未从设备材质方面考虑防腐蚀问题，2004年以来管输大庆原油中混入俄罗斯原油、冀东原油，混输大庆原油中硫的质量分数从0．1％升高到0．27％，酸值也从原来的0．04mgKOH／g升高到0．62mgKOH／g，装置设备腐蚀加剧，设备管道的现有材质已不能满足安全生产的需要。为提高装置设备抗腐蚀能力，Ⅱ套蒸馏装置对240℃以上设备、管道进行材质升级改造，升级后的材质按加工原油硫质量分数为0．5％，酸值为0．7mgKOH／g设计，材质升级的范围包括加热炉、塔器、冷换设备和管道等。该文通过对材质升级前后原料性质、腐蚀在线系统数据的对比分析，得出在原料性质基本不变的情况下，设备材质升级部分的管道腐蚀速率大幅下降，管道防腐蚀效果明显。检验了材质升级理论的抗腐蚀效果是可行的。
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