Aqueous phase process environments containing sulfur and specifically, hydrogen sulfide (H_2S), are generally referred to as sour environments or sour service. H_2S is a flammable, colorless gas that poses a process safety risk to plant personnel due to its toxicity. Furthermore, H_2S (and sulfur) can occur naturally or can be generated from common oil and gas production/refining methods. H_2S contributes to corrosion mechanisms such as high temperature sulfidation (H_2/H_2S corrosion) and acidic sour water corrosion; however, the cracking mechanisms associated with hydrogen charging in wet H_2S environments are the focus of this Damage Control series. Wet H_2S damage can detrimentally affect the load-carrying capacity of pressure retaining equipment and can manifest itself in numerous forms of material degradation, including the following: 1. Hydrogen blistering; 2. Hydrogen induced cracking (HIC); 3. Stress-oriented hydrogen induced cracking (SOHIC); 4. Sulfide stress cracking (SSC).
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