Corrosion condition of the inner wall surface at the fourth line section of the atmospheric and vacuum distillation columns in petrochemical industries
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The image below shows the corrosion on the inner wall of line 4 in the atmospheric and vacuum distillation towers used in the petrochemical industry. The structural type is vertical, with specifications of ф5000/ф8200/ф10000×22×59925. The material is 16MnR, and the operating medium is normal bottom oil vapor. Temperature 395 degrees, pressure is full vacuum. This tower has been in use for over 2 years, and corrosion has appeared on some parts of its metal surface; the form of this corrosion is mainly pitting corrosion.
Due to operating under high temperature and full vacuum conditions for a long period of time, along with the use of constant-bottom oil vapor as the operating medium, the 16MnR metal material is prone to pitting corrosion in such an environment. Pitting corrosion is usually caused by localized chemical or electrochemical reactions, which lead to rapid loss of metal in small areas on the material surface, resulting in the formation of small holes. This phenomenon occurred after more than two years of use, indicating that the tower’s corrosion resistance needs to be improved or regular maintenance inspections should be carried out. .