Prediction of Hydrogen Explosions and Their Effects on Vessels: A Design Approach

The use of the simulation code, FLACS, to determine the onset of detonation in a deflagration explosion is a significant step forward in determining the behavior of a deflagration in piping systems. Over time, it is envisaged that the software will be greatly enhanced to fully model a DDT. Generally, in blast analysis, deflagration can be the worst loading condition. This is due to the amount of energy that a deflagration imposes on a structure. In a detonation explosion, the pressures are high but durations are short, thus the amount of energy being applied is small when compared to deflagrations that have a low pressure and a long duration. This long duration has a detrimental effect on the structure. In the analysis performed, no plastic deformation is allowed and the dynamic load factors (DLF’s) are expected to be high since the material is not allowed to absorb any of the impulsive energy which in blast design is taken by the plastic deformation of the material. The analysis results show that the longer the duration of the detonation portion of the DDT, the higher the DLF’s with the DLF’s utlimitely leveling off at the theoretical level of 2 for the top head models. The results show that pipe sizes do not have a significant factor on the results with the worse effective area occurring locally around the nozzle.