Low-Temperature Hot Corrosion in the Refining Industry

Hot corrosion is an accelerated degradation (oxidation and/or sulfidation) of metals and alloys in the presence of liquid melts of salts and/or oxides. It’s generally divided into two forms: Type I and Type II.  Type I hot corrosion usually occurs at 850- 950 ºC (1550-1750 ºF), and it is also known as high-temperature hot corrosion.  Type II hot corrosion occurs at 600-800 ºC (1112-1472 ºF).  Type II hot corrosion is also called low-temperature hot corrosion, such as fuel-ash, oil-ash corrosion on refinery heater fired side tube surface resulting from fuel impurities.  Another potential location for Type II hot corrosion is FCCU regenerators, where the operating temperatures are normally in the range of 650 to 788 ºC (1200 to 1450 ºF).  The mechanisms and characteristics of Type II hot corrosion will be presented.  The analytical methods and mitigation strategies for Type II hot corrosion will also be discussed.