Hydrogen embrittlement in storage tank materials and welded joints

Hydrogen embrittlement (HE) poses a significant threat to the structural integrity and long-term reliability of its storage tanks, particularly in welded joints, where microstructural heterogeneities increase susceptibility. This review presents a comprehensive analysis of HE phenomena, emphasizing its critical role in material degradation. The paper begins by outlining the fundamentals of HE, describing how atomic hydrogen infiltrates metallic lattices, leading to loss of ductility and premature failure. Various HE mechanisms, including hydrogen-enhanced decohesion (HEDE), hydrogen-enhanced localized plasticity (HELP), and hydrogen-induced cracking (HIC), are discussed and classified based on their underlying physical principles. The susceptibility of commonly used storage tank materials, such as high-strength steels and aluminum alloys, is evaluated, with a focus on microstructural and compositional factors. Special attention is given to the welded regions, where residual stresses, grain boundary structures, and weld metal (WM) composition play a pivotal role in accelerating HE. The review also highlights key factors influencing HE in welded joints, including hydrogen diffusion pathways, welding processes, and post-weld treatments. Experimental methodologies, such as slow strain rate testing and thermal desorption analysis, are discussed alongside simulation approaches that model hydrogen diffusion and crack propagation. Finally, the paper outlines current mitigation strategies, including material selection, heat treatment, hydrogen barriers, and cathodic protection, offering insights into practical solutions for reducing HE risks in hydrogen storage systems. This review aims to guide future research and inform engineering practices for safer hydrogen infrastructure.