With the development of the light hydrocarbon recovery process in domestic natural gas processing plants, the shortage of raw materials for ethylene production in recent years is expected to be compensated domestically, and the ethane transportation pipeline needs rapid development.Given the physical properties of ethane products, both gaseous and liquid transportation have relative feasibility.Among them, compared to the liquid delivery, the gaseous transportation pipeline has a lower operating pressure and has certain advantages in medium and short distance transportation.Under shutdown conditions, due to the influence of the environment, the liquification of gaseous ethane may be caused.The phase change law and characteristics of the liquification have certain influence on the determination of the normal transmission conditions of the pipeline, the pipeline diameter, and the plan for restarting the shutdown transmission.It is necessary to make in-depth understanding and exploration.The study shows that the system pressure has a great influence on the pipe diameter selection of gaseous ethane pipelines; the lowest pressure of the system during the shutdown process occurs near the dew point pressure corresponding to the ambient temperature.Based on the physical characteristics of ethane products, combined with the requirements of the gaseous transportation technology, the influence of system pressure on the pipeline design was elaborated,and the liquefaction conditions for stopping the transmission of gaseous ethane pipelines in winter were qualitatively discussed,and simulations were performed with software.Maintaining the stability of system pressure is the key to avoid excessive low temperatures in the pipeline during the restart process.The research results can provide reference for the design of gaseous ethane pipelines.