High Temperature Corrosion

Corrosion damages that occur above 200-260°C (392-500°F) are commonly classified as high-temperature corrosion mechanisms. High-temperature corrosion reactions typically involve direct interaction with oxygen (oxidation), molecular hydrogen (HT Hydrogen Attack), or species such as sulfur (sulfidation, high-temperature H2-H2S corrosion).

Carburization

The carburization of steels and alloys occurs virtually during any high-temperature process (>593°C) in the presence of carbonaceous compounds, such as various hydrocarbons, CO, or coke. The degradation of metallic structures due to carburization remains difficult to predict accurately, potentially leading to unforeseen failures in high-temperature operating equipment. The forthcoming chapter offers a comprehensive overview of the carburization process, detailing its primary parameters and suggesting mitigation measures.

Creep and Stress Rupture

Creep and stress rupture is a form of time-dependent deformation and failure that occurs in materials subjected to high temperatures and sustained stress. It is significant concerns in refinery, particularly for high-temperature equipment and components such as reactors, furnaces, piping/tubes, and reformers. It can compromise the integrity and reliability of refinery equipment, leading to costly downtime, maintenance, and potentially hazardous situations.

High Temperature H2-H2S Corrosion

High-temperature H2-H2S corrosion is typically categorized as a sulfidation process assisted by hydrogen, as opposed to sulfidation occurring without the presence of H2. This form of corrosion is predominantly associated with hydroprocessing operations, where temperatures rise above approximately 230°C (450°F), and both H2S and hydrogen are present. The forthcoming chapter will delve into the primary characteristics of H2-H2S corrosion, highlighting essential parameters and offering a tools for estimating corrosion rates

Naphthenic Acid Corrosion

Naphthenic acid corrosion (NAC), along with high-temperature sulfidation, is commonly recognized as two primary damage mechanisms prevalent in the high-temperature sections of atmospheric and vacuum distillation units. The subsequent chapter offers an overview of the naphthenic acid corrosion mechanism, including process-corrosion relationships and solutions for corrosion mitigation.

Sulfidation (w/o H2)

Processing crude slates with an escalating concentration of sulfur species amplifies sulfidation processes within the high-temperature sections of Atmospheric and Vacuum Distillation Units (CDU/VDU). This chapter aims to offer a comprehensive understanding of the sulfidation mechanism, coupled with the relationships between process variables and corrosion. Following this, we will delve into general guidelines for material selection in the context of sulfidation.