Corrosion Control Strategies for Sulfur Recovery Units: Insight from Case Studies

Sulfur Recovery Units (SRU) are critical components in gas plants and refineries, responsible for converting hydrogen sulfide (H2S) to elemental sulfur. This process is crucial from an environmental perspective as it prevents the release of toxic gases into the atmosphere. However, operating the unit under harsh conditions, including high temperatures and aggressive environments, can expose it to severe degradation in the form of corrosion and cracking, which requires appropriate implementation of mitigation strategies. This paper presents two cases with distinct corrosion challenges encountered in SRU acid gas preheater tubes and associated piping circuits. The first case focuses on polythionic acid stress corrosion cracking found in austenitic stainless-steel tubes of acid gas preheaters. The second case highlights the challenge of acid dew point corrosion affecting the downstream piping circuits of acid gas preheaters. Furthermore, the paper offers recommendations for the optimal operational practices of acid gas preheaters to ensure asset integrity. It also details the adequate corrosion control measures required to mitigate the risks and ensure the long-term asset integrity of the assets. The insights and conclusions offered in this work provide a clear path forward for addressing corrosion challenges in similar SRUs and ultimately fostering safer and more efficient operations in the industry.