Hazard of Pressurized Tanks Involved in Fires

Abstract

Tanks devoted to the storage and transportation of liquefied petroleum gases (LPGs) are exposed to serious hazards when involved in a fire. Under particular conditions, the boiling liquid expanding vapor explosion (BLEVE) can occur with catastrophic consequences. In the present paper, a mathematical model developed to evaluate the LPG tank behavior for different fire scenarios is presented. Major hazards have been identified distinguishing, in order of gravity, among jet release, catastrophic loss of containment, i.e., the failure of the tank followed by rapid evaporation of the superheated liquid without the development of blast waves, and BLEVE. The effects of accidental cracks, of the presence of a pressure safety valve, and of an insulating layer have been investigated as well. Eventually, the severity of the fireball, of the blast wave, or of the fragments produced by the BLEVE has been assessed as a function of both the scenario and the thermal condition of the containment at the moment of failure.

Escalation thresholds in the assessment of domino accidental events

“…the liquid temperature should be higher than superheat temperature) that are seldom verified during an accidental event. More often, vessel failure results in a simple loss of containment without the formation of a blast wave due to liquid explosion [8]. This was recently confirmed by Van den Berg et al [39], who estimated that a blast wave is formed only if the catastrophic disintegration of the entire vessel takes place in a limited time frame.…”

“…Details on the model employed for the calculation of ttf values are reported elsewhere [8,38]. Figs.…”

“…Table 5 summarizes the diameter, the duration and the heat radiation at ground level as a function of distance from the ground projection of cloud border, resulting from the assessment of the fireball scenarios by conventional literature models [17,19]. As discussed above, the values of the ttf for the reference vessels were calculated by standard models [8,10], without taking into account any protection or mitigation system (in particular, no thermal insulation was considered). An example of the detailed results obtained by this procedure is given in Table 7, which shows the values of the ttf for the reference set of pressurized vessels, calculated for the more severe fireball among those defined in Table 5.…”

“…The main parameters that should be taken into account in the analysis of possible escalation sequences were identified and assessed. The results of recent studies concerning the analysis of equipment damage data and the development of equipment damage models [6][7][8][9] were the starting point of the present investigation, and were used to assess escalation credibility and to develop detailed escalation criteria. It is also worth mentioning that the present study was carried out within a more general research project, aiming at the development of models and software tools for the quantitative assessment of domino effect in QRA [10][11][12][13].…”

The development of an inherent safety approach to the prevention of domino accidents

“…The explosion effects were calculated by the standard literature approach considering the liquid at the superheat temperature (CCPS, 1994). The results obtained for propane are conservative for butane and for LPG mixtures (Salzano et al, 2003).…”