Investigation of Corrosion Rate in ISOMAX Unit

Corrosion presents a significant challenge in the operation and maintenance of refinery units, particularly in the ISOMAX unit, which is essential for upgrading gasoline quality through isomerization of light hydrocarbons. This study investigates the corrosion behavior within the ISOMAX unit by analyzing the factors influencing corrosion rates, the prevalent corrosion mechanisms, and potential mitigation strategies. The ISOMAX unit operates under high temperature and pressure conditions with feedstock containing sulfur compounds, chlorides, and traces of water, all of which contribute to a corrosive environment. Corrosion assessment was conducted using in-situ corrosion probes, metallurgical examinations, and chemical analyses of process fluids. The results showed an average corrosion rate of approximately ۰.۱۵ mm/year in carbon steel components, with localized pitting corrosion observed near weld zones due to chloride accumulation. Sulfur-induced corrosion products such as iron sulfides were also identified, confirming the chemical attack on metallic surfaces. Hydrogen embrittlement was found to be minimal, indicating effective hydrogen control in the system. To mitigate corrosion, recommendations include pretreatment of feedstock to reduce impurities, employing corrosion-resistant materials in critical areas, using corrosion inhibitors, and maintaining optimized operational parameters. Implementing these strategies can significantly reduce corrosion impact, improve equipment longevity, and ensure safer and more efficient operation of the ISOMAX unit. This study underscores the importance of continuous monitoring and proactive maintenance to manage corrosion risks in refinery isomerization processes.

Keywords:

ISOMAX unit , corrosion rate , Pitting Corrosion , sulfur-induced corrosion , chloride stress corrosion cracking