Objective Using new or existing oil and gas pipelines to transport gaseous CO₂ offers an economical solution for short-distance CO₂ transport in Carbon Capture, Utilization and Storage (CCUS) projects. However, CO₂ pipelines are susceptible to stress corrosion cracking (SCC) under severe internal corrosion and external stress, raising concerns about their service reliability.

Methods The research status of SCC in CO₂ pipelines across different phases was comprehensively reviewed. Corrosion behavior, crack initiation, and propagation mechanisms were explored with a focus on the gaseous CO₂ transportation environment. The synergistic process of anodic dissolution–film rupture and hydrogen-induced cracking in this environment was elaborated. Subsequently, the multi-factor coupling effects of material properties, environmental conditions, and stress states on the SCC susceptibility of pipeline steel were systematically analyzed, and existing research deficiencies were summarized.

Results The relatively low pressure of gaseous CO₂ causes localized condensation of the aqueous phase on the pipe wall as micro-droplets, forming a discontinuous, porous FeCO₃ corrosion product film that offers limited protection. In the microstructure, fine acicular ferrite promotes passive film nucleation due to its high dislocation density. Non-metallic inclusions facilitate crack nucleation by inducing interfacial stress concentration, acting as hydrogen traps, and initiating micro-galvanic corrosion. Impurity gases in gaseous CO₂ increase SCC susceptibility by altering aqueous phase precipitation, participating in cathodic reactions, and destabilizing the corrosion product film. Moisture, with its condensation behavior regulated by temperature and pressure, is a key factor in inducing local and top-of-the-line corrosion.

Conclusion Research on the SCC mechanism of gaseous CO₂ pipelines remains limited. To ensure the safe and stable operation of CO₂ transportation pipelines, future studies should focus on: clarifying the effects of flow velocity, shear force, and phase changes on the formation and growth of local corrosion pits in gaseous CO₂ environments; monitoring and analyzing in-situ electrochemical corrosion data in gaseous CO₂ with trace water under external stress; and expediting the development of an SCC evaluation system for in-service oil and gas pipelines repurposed for gaseous CO₂ transport.