Objective China’s ammonia-hydrogen green energy industry is developing rapidly. This has created an increasingly urgent engineering demand for long-distance, large-scale liquid ammonia pipeline transportation. Liquid ammonia pipelines serve as critical infrastructure within the ammonia-hydrogen energy transmission system. Ensuring their safe and efficient operation is important for supporting the large-scale application of clean energy and advancing the development of new-energy storage and transportation chains.

Methods The recent progress of liquid ammonia pipeline transportation technologies at home and abroad is systematically investigated and summarized. This study focuses on five key areas: material performance evaluation, pipeline transportation process, safety monitoring and assessment, emergency protection, and standard systems. It analyzes the shortcomings of the existing liquid ammonia pipeline technology system and identifies key scientific problems and core technical challenges restricting engineering application.

Results Current liquid ammonia pipeline transportation technologies have achieved phased research progress. The physical property parameters of pure ammonia, steady-state hydraulic-thermal calculation models, and understanding of mechanisms under partial transient operating conditions are becoming increasingly mature. The prevention and control mode for liquid ammonia Stress Corrosion Cracking (SCC) has shifted from simple empirical inhibition. It now relies on a comprehensive strategy. This strategy centers on multi-impurity synergistic regulation, welding residual stress control, and hardness index constraint. Leakage monitoring techniques and accident consequence assessment methods are continuously being improved. Emergency protection technologies such as water curtain for ammonia suppression have also attracted extensive attention. Nevertheless, the large-scale safe transportation of liquid ammonia via pipelines still faces prominent technical bottlenecks. The thermophysical properties and unsteady phase-change mechanisms of liquid ammonia containing multi-impurity components remain unclear. The engineering applicability of laboratory material evaluation results lacks effective verification. The coupled evolution mechanism of multi-physical fields under complex terrain and offshore operating conditions is insufficiently understood. An integrated intelligent technical system for safety monitoring and emergency protection has not yet been formed. Meanwhile, dedicated standards and specifications applicable to long-distance liquid ammonia pipelines are still relatively scarce.

Conclusion Future research needs to develop multi-physical-field coupled simulation models and corrosion fatigue life prediction models, and establish a dedicated standard system for liquid ammonia pipelines covering material evaluation, process design, and safety emergency response. By integrating artificial intelligence technology, an integrated safety protection system should be constructed. It is based on intelligent perception and covers “real-time prediction-risk assessment-emergency decision-making.” This system should enable dynamic early warning of leakage and dispersion as well as automated emergency response, and drive the safe, efficient, and large-scale deployment of liquid ammonia pipelines.