某液化天然气公交车发生故障后，关闭其气瓶截止阀，供气系统出现管道冰冻、天然气泄漏现象。用常温自然水对管道进行除冰时供气系统中的缓冲罐发生爆炸。采用化学成分测试，显微组织、断口形貌观察以及应力校核等方法，对缓冲罐的爆炸原因进行了分析。结果表明：采用常温水除冰时液化天然气发生快速相变，导致系统内压力急剧升高并超过缓冲罐的爆炸压力，从而引发缓冲罐爆炸；建议在缓冲罐顶部加装二级安全阀，同时为安全阀设置排空管，通过排空管泄压来有效降低缓冲罐爆炸的风险。

After breakdown of a liquefied natural gas bus, the cut-off valve of the gas cylinder was closed.And then the gas supply system experienced pipeline freezing and natural gas leakage.The buffer tank in the gas supply system exploded when the pipeline was deiced with normal temperature natural water.The explosion reason for the buffer tank was analyzed by chemical composition test, microstructure and fracture morphology observation, and stress checking.The results show that the liquefied natural gas experienced rapid phase transition during the deicing with normal temperature water, leading to sharply increased pressure in the system.When the pressure exceeded the explosion pressure of the buffer tank, the buffer tank exploded.It was suggested to install a secondary safety valve on the top of the buffer tank, and to set a vent pipe for the safety valve.The risk of explosion of the buffer tank could be effectively reduced by venting the pressure through the vent pipe.