Leak and explosion from an underground pipeline in Kaohsiung, Taiwan

摘要

On 31 July 2014, at 23:57, a catastrophic vapour explosion occurred in the downtown area of Kaohsiung city, Taiwan. The incident was initiated from a leak of an underground pipeline transporting pressurised propylene liquid. Analysis of pipeline operation logs and release modelling suggested that at least 90,000 kg of propylene leaked, entering the underground trench and spreading 4.5 km in distance before meeting an ignition source three hours later. The ignition caused a significant confined vapour explosion which blew up the road above the underground trench, resulting in thirty two fatalities, more than three hundred injuries and damage to more than one hundred vehicles. This incident bears similarities to two previous incidents: the explosion in Guadalajara, Mexico, in 1992, caused by a gasoline leak into a sewer through a corroded pipeline which resulted in 252 fatalities and more than 1500 injuries; and the explosion in Qingdao, China, in 2013, caused by a leak of crude oil from a corroded pipeline into the city storm drains which resulted in 62 fatalities and 136 injuries. Key factors contributing to the large number of fatalities and injuries in these incidents include the very large quantity of flammable mass leaked, the confinement in the sewer or drain, and the proximity of well-populated communities. There was however a subtle difference in the Kaohsiung case in that the leak source was a pressurised, flashing liquid which would vaporise completely upon leak into ambient environment, while the other two cases dealt with flammable liquids with only partial vaporisation. Challenges and recommendations in addition to detailed analysis of the incident are given to prevent and mitigate the occurrence of similar incidents.