Adriana Palacios

Domino effect in chemical accidents: main features and accident sequences.

The main features of domino accidents in process/storage plants and in the transportation of hazardous materials were studied through an analysis of 225 accidents involving this effect. Data on these accidents, which occurred after 1961, were taken from several sources. Aspects analyzed included the accident scenario, the type of accident, the materials involved, the causes and consequences and the most common accident sequences. The analysis showed that the most frequent causes are external events (31%) and mechanical failure (29%). Storage areas (35%) and process plants (28%) are by far the most common settings for domino accidents. Eighty-nine per cent of the accidents involved flammable materials, the most frequent of which was LPG. The domino effect sequences were analyzed using relative probability event trees. The most frequent sequences were explosion→fire (27.6%), fire→explosion (27.5%) and fire→fire (17.8%).

Jet fires: a "minor" major accident?

Jet fires have received only a rather reduced attention as compared to other types of fires; this is nprobably due to the fact that they are usually much smaller that fireballs, pool fires or tank fires. nHowever, jet fires often occur in areas where there is other equipment and the probability of flames nimpinging on a pipe or a vessel can be high. Furthermore, due to the turbulence of the phenomenon, nthe combustion in such fires is very good and high heat fluxes can seriously affect this equipment, thus noriginating a domino effect which will enlarge the scale of the accident. A historical survey has shown nthat, of the jet fires reported in accident data bases, 50 % caused another event with severe effects. In n90 % of the domino effect cases there was an explosion, usually of a vessel; this was especially nfrequent in transportation accidents. In this communication the main features of jet fires are ncommented: most frequent domino effect sequences, shape and size, thermal behaviour, mathematical nmodelling.