Abstract: LNG unloading arm is an important connection channel between LNG carrier and receiving station pipeline, and is the core equipment of receiving station. The PHAST software was adopted to simulate the consequences of LNG leakage, natural gas diffusion, fire and explosion under the emergency detachment condition of the 16″ LNG unloading arm of one project. The results show that in general, the consequences of vertical downward leakage are more serious than those of vertical upward leakage; in the vertical downward leakage scenario, LNG may contact the lower deck and form a liquid pool; in all kinds of scenarios that may lead to serious consequences, the influence distance of jet fire is the furthest when the weather type is 1/F and the vertical downward leakage occurs; the influence range of the theoretical fatality rate 1 is 31.71 m downwind. Based on the analysis results, relevant suggestions are put forward for targeted and effective protection. Meanwhile, management of ship and dock personnel activity is strengthened to ensure the safe and reliable operation of the LNG unloading arm for a long period.

Key words: unloading arm, emergency detachment, gas cloud diffusion, fire, explosion