Vent burst pressure effects on vented gas explosion reduced pressure

The overpressure generated in a 10 L cylindrical vented vessel with an L/D of 2.8 was investigated, with end ignition opposite the vent, as a function of the vent static burst pressure, Pstat, from 35 to 450 mb. Three different Kv (V2/3/Av) of 3.6, 7.2 and 21.7 were investigated for 10% methaneeair and 7.5% ethylene eair. It was shown that the dynamic burst pressure, Pburst, was higher than Pstat with a proportionality constant of 1.37. For 10% methaneeair Pburst was the controlling peak pressure for K Pburst in the literature and in EU and US standards. For higher Kv the overpressure due to flow through the vent, Pfv, was the dominant overpressure and the static burst pressure was not additive to the external overpressure. Literature on the influence of Pstat at low Kv was shown to support the present finding and it is recommended that the influence of Pstat in gas venting standards is revised

Missing safety measures led to the jet fire and seven deaths at a steel plant in Turin. Dynamics and lessons learnt

The Authors of this paper are the technical experts that were entrusted by the Public Prosecutor to conduct the technical inquiry into the accident that occurred in the ThyssenKrupp plant in Torino on December 6, 2007. The paper contains the results of the inquiry under the above mentioned point of view. The dynamics of the accident, the main causes and the consequences have been defined. This was an unusual accident from which important lessons can be learned. On December 6, a modest fire developed in the entry section of a pickling and annealing line in the TK plant in Turin. The eight workers on duty seized the firefighting equipment and started to try to extinguish the fire. The workers had portable fire extinguishers and a fire hydrant, so they had to get close to the fire to fight it. Suddenly, a violent jet fire, caused by the rupture of a hydraulic circuit, occurred. The flame instantaneously struck the eight workers while they were still fighting the fire. Seven workers suffered very serious burns, one died instantaneously while the other six had over the following month. One of the workers, who was partly protected by an operating machine, suffered only minor burns and survived. The paper contains some important lessons that have been learned from the present case, which demonstrate that the fire risk at pickling and annealing lines has generally been underestimated by the steel industry. The fire risk due to hydraulic actuators is also evident and new fire fighting strategies are suggested