Cause Analysis of the Large-Scale LPG Explosion Accident Based on Key Investigation Technology: A Case Study

Blending dimethyl ether (DME) into liquefied petroleum gas (LPG) has become a common phenomenon. On December 3, 2019, an LPG/DME explosion occurred in Beijing, resulting in 4 deaths and 10 injuries. To deeply investigate the cause and explosion process of the explosion accident, the accident investigation method combining on-site inspection, material evidence analysis, experimental verification, and logical reasoning was used. In addition, the location of the ignition point, the explosive substances, the cause of the gas leakage, the process and the distribution characteristics of the gas leakage, and the ignition process were successively reasoned and analyzed in detail. The results show that the LPG/DME-blended gas can effectively corrode silicone flange gaskets, forming laminar fractures and radial cracks on the gasket. As a result, the tensile strength of the gasket decreased. Under the action of the gas pressure inside the pipeline, the gasket was torn and a leakage hole was formed. The leaked combustible gas formed at least 305 m3 of the explosive gas mixture inside and outside the refrigerated storage. The investigation and research results have important scientific guiding significance for revealing the cause and preventing similar accidents.