Explosion of fixed roof atmospheric storage tanks, part 2: Analytical methods to assess safety distances

Abstract

Many flammable products are stored in large tanks at atmospheric pressure. Ignition of a hydrocarbon–air mixture in such tanks can lead to an explosion and cause lethal casualties or damage to the surrounding facilities and buildings. To apprehend this, safety distances for humans, structures, and equipments need to be defined. Several simple methodologies have been set up to estimate safety distances in case of an atmospheric storage tank explosion. After giving an overview of past accidents [1], this second article focuses on assessment of safety distances using analytical methods available in the open literature. A short theoretical background is first exposed to understand phenomena involved in vented gas explosions. Then, a summary of current methodologies and corresponding assumptions used to evaluate external overpressure in case of a tank explosion is given. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2012

Explosion of fixed roof atmospheric storage tanks, part 3: Gas explosion and structural response simulations

“…Table 8 compares energies obtained with analytical methods, previously described in Ref. 2, and the energy calculated using FLACS. Results largely differ depending on the methodology used (from 69 to 1,247% of E FLACS for the compact tank; from 23 to 420% of E FLACS for the elongated tank).…”

“…FLACS simulations were performed to assess safety distances for two types of tanks: compact tank ( H / D < 1): D = 60 m; H = 14 m (same case as in Ref. 2); P F = 0.5 barg (Figures 6a–6c); elongated tank ( H / D > 1): D = 9 m; H = 14 m (same case as in Ref. 2); P F = 1 barg (Figures 7a–7c). …”

“…The second paper [2] focused on assessment of safety distances using analytical methods available in the open literature.…”

“…Regarding the significant discrepancies found in the values of safety distances calculated with the eight analytical methods described in Ref. 2, a numerical study was performed with CFD softwares FLACS and LS–DYNA, to estimate bursting pressures reached during an atmospheric storage tank explosion (in accordance with the latest standards related to atmospheric tank design), and also to quantify the importance of energy losses (due to tank deformation and ejection of fragments). This study is summarized in this article.…”

Velocity and range of fragments from accidental explosions

“…No satisfactory approach for evaluating the parameters of flying fragments has yet been developed. A literature survey showed that much effort was dedicated to explosive loading of structures [1] as well as to processes connected with pressure vessels and bursting tanks [2]. Only a little information was found concerning the problem of secondary fragments caused by accidental explosions.…”