Abstract: Aiming at the gas pipeline jet fire accident, a three-pipe parallel bridge crossing pipeline is taken as the research object. This paper took Fluent to carry out numerical simulation of natural gas jet fire, and the combustion characteristics of jet fire is analyzed based on fire flame length, temperature and heat radiation distribution under different leakage diameters. And the thermal response of adjacent oil pipelines under different oil flow rates were studied. The results show that: the flame maximum temperature is about 1 980 ℃. When the leakage diameter increases from 6.4 mm to 101.6 mm, the flame length, personnel and equipment damage spheres increase to 8.09 times, 7.13 times, and 6.70 times, respectively. The maximum temperature position moves to 36.4% of flame length from 12.5%. The adjacent pipeline temperature and pipeline equivalent stress are positively correlated with the leakage diameters.When the thermal stress is the dominant factor, the equivalent stress decreases with the flow rate increases, while the equivalent stress increases with the flow rate increases. Considering the variation of the equivalent stress and yield strength, it is recommended that the adjacent pipelines operate at 1.35~1.40 m/s in case of an accident. Based on the results, the paper proposes practical measures on the emergency operation to provide a basis for the accident disposal.

Key words: jet fire, combustion characteristic, thermal failure, domino effect, emergency measure