Household LPG cylinder fracture and a boiling liquid expanding vapor explosion

Abstract

Liquefied petroleum gas (LPG) cylinders are designed as thin-wall pressure vessels consisting of a cylindrical body and two almost hemispherical bottoms made of low carbon steel and welded together. LPG cylinders design, manufacturing, inspection and testing follow specific rules, Norms and Regulations. Pressure vessel design theory along with National Regulations and Product Specifications in force provide the initial design parameters and safety margin assumptions. A serious accident occurred on April 2, 2015 at Loutron village, close to the city of Amfilochia, in western Greece, explosion of an LPG bottle at a local restaurant. Five fatalities were reported at the time of the accident and three more injured were pronounced dead some months later. The accident gained extended publicity from the media arising concerns about safety in LPG distribution and operation. The local police requested an expert’s appraisement from the Mechanical Engineering and Aeronautics Department of the University of Patras, for the evaluation of the accident’s contributing factors. The accident investigated was a «boiling liquid expanding vapour explosion», and revealed potential threats from the operation of aged LPG bottles, and marginal inspection and testing procedures followed. A detailed analysis of the LPG cylinder operational characteristics along with a systematic design approach, fatigue, and failure analysis is presented here. The legislation in force, Regulations and Norms are also reviewed.