Abstract: Charpy impact test at a series of temperatures (from -80 ℃ to -20 ℃) was done to base metal and weld of the helical welding pipes of a high pressure gas station,and the ductile-brittle transition temperature and applicable temperature of the pipe were measured by analyzing the impact absorbed energy-temperature curves and the fracture morphology.The results show that the ductile-brittle transition temperatures (50% impact absorbed energy) of base metal and weld of the pipe were -34.73 ℃ and -37.02 ℃,respectively.According to ISO 3183-2007,the base metal and weld of the pipe could meet the operating requirements of low temperature environment of -80 ℃ and -40 ℃,respectively.