Which of the following are affected by sulfidation?

Sulfidation, also known as high-temperature sulfidic corrosion, is a non-aqueous corrosion mechanism that occurs in petroleum refining processes at temperatures above 400°F (204°C). It involves the reaction of reactive sulfur species, such as hydrogen sulfide and elemental sulfur, with metallic equipment components. While alloying with chromium significantly increases resistance to sulfidation by forming a protective chromium sulfide scale, all iron-based alloys including carbon steel, 400 series stainless steels, and 300 series stainless steels remain susceptible under specific temperature, sulfur concentration, and velocity conditions. Carbon steel experiences severe thinning at lower temperatures, whereas 400 and 300 series stainless steels can still undergo sulfidation at elevated temperatures or in high-velocity streams.

A. Carbon steel is highly vulnerable to sulfidation at temperatures above 400°F, but it is not the only material listed that suffers from this damage mechanism.
B. 300 series stainless steels contain chromium which provides resistance, but they remain susceptible to sulfidation at higher operating temperatures and severe conditions.
C. 400 series stainless steels offer moderate sulfidation resistance due to chromium content, but can still corrode significantly under high-temperature sulfidic environments.

1. API Recommended Practice 571, "Damage Mechanisms Affecting Fixed Equipment in the Refining Industry," Third Edition, March 2020, Section 3.61, Sulfidation.

2. API Publication 939-C, "Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil Refineries," First Edition, 2009, Section 4.1.

3. High-Temperature Corrosion, Weldon Materials Handbook, ASM International, 2006, Chapter 5.