Abstract
Process equipment containing hazardous or flammable materials in petrochemical facilities can be subjected to significant blast loads from accidental Vapour Cloud Explosions (VCE). Storage tanks are of particular importance, since these can potentially contain significant amounts of such materials. Calculating the response (damage) of particular types of tank and associated equipment under explosion blast loads can be complicated and expensive. Moreover, determining if the predicted damage has any potential for releasing the contents of the tank can be challenging and involve complex calculations. Simplifications can be made to model certain types of equipment such as bullet tanks in order to obtain qualitative estimates of damage based on empirical data, analytical approximations, and observed damage from industrial explosions. The simplified models can be used to assess the potential for damage in terms of the peak pressure (P) and impulse (i) which is the integral of pressure-time function. These parameters can be used to define any blast load. Therefore, the damage estimate is not only dependent on the equivalent static pressure, but takes the blast duration into account.
Pressure-impulse (P-i) curves can be used to graphically define the magnitude of any potential explosions as pressure-impulse combinations that cause specific damage levels. Using P-i curves developed for increasing damage levels, qualitative damage levels can be defined as the area bound in a pressure-impulse diagram between two curves. Calculated VCE blast loads can be plotted on the P-i diagram to perform qualitative blast assessment of the equipment damage. Furthermore, the tank (or other equipment) model can be used to produce damage contours on a plant plot plan that can be used as an aid in new plant facility siting.
