• Significant hydrogen carrier potential of Liq.NH₃ for hydrogen transport is analyzed.
• Field failure and laboratory-based studies are reviewed.
• Diverse range of factors causing Liq.NH₃ SCC are discussed.
• Insightful analysis of the proposed underlying mechanism is presented.
• Critical overview of codes, testing protocols, challenges, and future aspects is provided.

Liquid ammonia (Liq.NH₃) has long served industrial applications and is now gaining prominence as a hydrogen carrier, offering nearly double the gravimetric hydrogen density of liquid hydrogen (Liq.H₂) at far milder storage conditions. However, stress corrosion cracking (SCC) in steel poses a critical risk to ammonia storage tanks and pipelines. Despite its industrial significance, literature on Liq.NH₃ SCC is limited. This review systematically consolidates historical and recent studies, encompassing field case investigations and laboratory experiments. Key influencing factors, i.e., impurities, steel strength and hardness, welding practices, temperature, and galvanic effects, are critically analyzed. Commonly used steel materials, evaluation methods including SSRT, four-point bending, tuning-fork specimens, electrochemical polarization, SEM analysis, and testing protocols are compared. While current Liq.NH₃ SCC research relies predominantly on empirical and phenomenological approaches, advanced techniques such as XPS, ICP-OES, and computational analysis remain relatively underexplored and are identified as promising tools for future investigations. By integrating past knowledge and emerging research opportunities, this study offers a comprehensive roadmap for ensuring the safe and reliable use of Liq.NH₃ in hydrogen storage and transport systems.

Refer to: https://www.sciencedirect.com/science/article/abs/pii/S0360319926016332