The power of the expanding vapour and flashing liquid release usually opens the vessel completely and flattens the open vessel cylinder wall on the ground. The pressure forces on the unsupported edges of the wall bend the vessel wall flaps up to open the vessel. In a single step BLEVE (Birk et al., 2007) this pin hole grows rapidly and continuously along the vessel top in the axial direction, then it turns circumferentially at both ends of the weakened length. It is known from high speed imaging (Laboureur et al., 2015) that the vessel failure starts as a pin hole near the top of the vessel wall in the severely heated (weakened) area.
This paper will focus on the blast wave, liquid flashing and ground loading. These near field effects include the blast overpressure, ground loading, overpressure and drag loading from the flashing liquid, projectile effects and of course the fireball if the cloud is flammable. Over the years the authors have been asked by emergency responders what the near field effects are. The most recent BLEVE in the news was one on a bridge in Bologna Italy in 2018 (, 2018).This tanker truck suffered a BLEVE and the load on the bridge caused the bridge deck to fail. There is a current need to understand the near field hazards from a BLEVE. We will come back to this point later in this paper. There is no mention of the atmospheric superheat limit in this definition, as mentioned in older definitions. The vessel must fail catastrophically and open fully to release its contents In this paper we use the following definition of a BLEVE (Birk et al., 2007) “the explosive release of expanding vapour and flashing liquid when a pressure vessel holding a pressure liquefied gas fails catastrophically”Īn explosion which suggests a supersonic shock wave is sent into the surroundingsĪ pressure liquefied gas must be present to generate a rapid phase change event The definition of BLEVE has evolved through the years with our understanding of it. This work aims at refining our understanding of the different physical phenomena involved in a BLEVE. However, models to predict these hazards consequences are based on diverging interpretations of the physics of the phenomenon (Laboureur et al., 2014). There has been a lot of studies on the multiple hazards this accident generates to understand it better and predicted its consequences (Abbasi and Abbasi, 2007 Eckhoff, 2014). Their consequences are often deadly and very destructive for the surrounding structures.
Many cases have been reported over the past 60 years throughout the world (Hemmatian et al., 2019). The Boiling Liquid Expanding Vapor (BLEVE) is a feared accident in the industry. A chronology of the event also shows that the lead shock is generated early in the explosion process, and is long gone before the liquid starts boiling, arguing that vapour expansion is the main contributor to the first shock overpressure. The imaging reveals presence of a Mach shock at the exit of the vessel at the early stage of the opening. This paper will focus on the early milliseconds of the process where the vessel begins to open and a shock wave is formed and moves out into the surroundings. We were specifically interested in the near field hazards including blast overpressure and ground force. The work was done to improve our understanding of the fluid – structure interactions during the fire heat induced failure of a pressure vessel holding a pressure liquefied gas. The tube was instrumented to capture failure characteristics (pressure, temperature) and consequences: blast overpressure and imaging of the propane cloud and shock around the vessel ground force under it transient pressure and imaging of the boiling process inside the vessel. The failure pressures ranged from 10 to 33 bar. The tubes were filled to a desired level with liquid propane and then the propane was uniformly heated electrically until the tubes failed. This paper describes small scale experiments of aluminum tubes that were weakened by machining a thinned wall area over a specified length. This paper will provide evidence that the latter description that is correct for most, if not all BLEVEs observed in practice.
Others believe it is the vessel rupture by some weakening process that leads to the BLEVE. Some believe the BLEVE is triggered by some pressure transient inside the vessel and this causes a superheat limit explosion which causes the vessel to rupture. Some still argue about what comes first, the BLEVE or the vessel rupture. The boiling liquid expanding vapour explosion (BLEVE) is well known but not well understood.
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