Gabriele Landucci

Experimental and Analytical Investigation of Thermal Coating Effectiveness for 3 m3 LPG Tanks Engulfed by Fire

Two large-scale diesel pool fire engulfment tests were carried out on LPG tanks protected with intumescing materials to test the effectiveness of thermal coatings in the prevention of hot BLEVE accidental scenarios in the road and rail transport of LPG. A specific test protocol was defined to enhance reproducibility of experimental tests. The geometrical characteristics of the test tanks were selected in order to obtain shell stresses similar to those present in full-size road tankers complying to ADR standards. In order to better understand the stress distribution on the vessel and to identify underlying complicating phenomena, a finite element model was also developed to better analyze the experimental data. A non-homogeneous and time-dependent effectiveness of the fire protection given by the intumescing coating was evidenced both by finite element simulations and by the analysis of the coating after the tests. The results of the fire tests pointed out that the coating assured an effective protection of the tanks, consistently increasing the expected time to failure. The data obtained suggest that the introduction of fire protection coatings may be a viable route to improve the safety of the LPG distribution chain.

Release of hazardous substances in flood events: Damage model for atmospheric storage tanks

Abstract The damage of storage tanks in flood events may lead to severe “natural-technological” (NaTech) accident scenarios due to the release of hazardous substances causing damage to people and environment. In the present study, damage of atmospheric storage tanks in floods was analyzed in detail. A mechanical damage model was developed and validated by available literature data on past accidents. Simplified correlations were then obtained to calculate the probability of loss of containment on the basis of severity parameters of the flood event. The tank vulnerability model was integrated in a comprehensive approach for the quantitative risk assessment of NaTech scenarios triggered by floods. A case-study was discussed to test the potentialities of the method.

Modeling the performance of coated LPG tanks engulfed in fires

The improvement of passive fire protection of storage vessels is a key factor to enhance safety among the LPG distribution chain. A thermal and mechanical model based on finite elements simulations was developed to assess the behaviour of full size tanks used for LPG storage and transportation in fire engulfment scenarios. The model was validated by experimental results. A specific analysis of the performance of four different reference coating materials was then carried out, also defining specific key performance indicators (KPIs) to assess design safety margins in near-miss simulations. The results confirmed the wide influence of coating application on the expected vessel time to failure due to fire engulfment. A quite different performance of the alternative coating materials was evidenced. General correlations were developed among the vessel time to failure and the effective coating thickness in full engulfment scenarios, providing a preliminary assessment of the coating thickness required to prevent tank rupture for a given time lapse. The KPIs defined allowed the assessment of the available safety margins in the reference scenarios analyzed and of the robustness of thermal protection design.

Quantitative assessment of safety barrier performance in the prevention of domino scenarios triggered by fire

The evolution of domino scenarios triggered by fire critically depends on the presence and the performance of safety barriers that may have the potential to prevent escalation, delaying or avoiding the heat-up of secondary targets. The aim of the present study is the quantitative assessment of safety barrier performance in preventing the escalation of fired domino scenarios. A LOPA (layer of protection analysis) based methodology, aimed at the definition and quantification of safety barrier performance in the prevention of escalation was developed. Data on the more common types of safety barriers were obtained in order to characterize the effectiveness and probability of failure on demand of relevant safety barriers. The methodology was exemplified with a case study. The results obtained define a procedure for the estimation of safety barrier performance in the prevention of fire escalation in domino scenarios.

Accident scenarios triggered by lightning strike on atmospheric storage tanks

Severe Natech accidents may be triggered by lightning strike affecting storage tanks containing relevant inventories of hazardous materials. The present study focused on the identification of event sequences and accident scenarios following lightning impact on atmospheric tanks. Reference event trees, validated using past accident analysis, are provided to describe the specific accident chains identified, accounting for reference protection and mitigation safety barriers usually adopted in current industrial practice. An overall methodology was outlined to allow the calculation of the expected frequencies of final scenarios following lightning impact on atmospheric storage tanks, taking into account the expected performance of available safety barriers. The methodology was applied to a case study in order to better understand the data that may be obtained and their importance in the framework of quantitative risk assessment (QRA) and of the risk management of industrial facilities with respect to external hazards due to natural events.

Heat Radiation Effects

Abstract Escalation triggered by fires resulting in domino scenarios was the cause of severe accidents in the process industry. As a matter of fact, the catastrophic failure of process equipment, both pressurized and atmospheric, may be induced by the heat-up due to the exposure to accidental fires, leading to the loss of containment of hazardous materials. In this chapter, the behavior of equipment exposed to accidental fire will be investigated in order to identify the fundamental mechanisms underlying the failure of vessels exposed to fire. In particular, both simplified tools and detailed models for the assessment of the performance of vessels involved in fires will be discussed. The final aim is to provide methods for the quantitative assessment of domino hazards caused by accidental fires, and for the application of both passive and active strategies for the control and reduction of the risk associated with incident escalation triggered by fire.

Quantitative assessment of risk due to NaTech scenarios caused by floods

Floods may cause severe damages to chemical and process facilities, triggering major accidents (fires, explosions, and toxic release). Such cascading events are termed as NaTech scenarios. In the present study, a specific methodology for the implementation of Quantitative Risk Assessment (QRA) of NaTech scenarios triggered by floods was further developed and applied to the assessment of different flood events and equipment categories. Specific vulnerability models allowed estimating the failure probability of both atmospheric and pressurized equipment, and the estimation of NaTech-induced release frequencies. A case-study representative of an industrial installation was discussed, comparing the risk due to conventional internal causes to that deriving from NaTech scenarios and identifying possible specific safety barriers. The case-study demonstrated that a significant risk increment may be associated to industrial facilities located in flood-prone areas when flood-triggered NaTech scenarios are considered.

Assessment of fragment projection hazard: probability distributions for the initial direction of fragments.

The evaluation of the initial direction and velocity of the fragments generated in the fragmentation of a vessel due to internal pressure is an important information in the assessment of damage caused by fragments, in particular within the quantitative risk assessment (QRA) of chemical and process plants. In the present study an approach is proposed to the identification and validation of probability density functions (pdfs) for the initial direction of the fragments. A detailed review of a large number of past accidents provided the background information for the validation procedure. A specific method was developed for the validation of the proposed pdfs. Validated pdfs were obtained for both the vertical and horizontal angles of projection and for the initial velocity of the fragments.

Application of dynamic Bayesian network to performance assessment of fire protection systems during domino effects

The propagation of fire in chemical plants – also known as fire domino effects - largely depends on the performance of add-on passive and active protection systems such as sprinkler systems, water deluge systems, emergency shut down and emergency blow down systems, fireproofing, and emergency response. Although such safety barriers are widely employed to prevent or delay the initiation or escalation of fire domino effects, their inclusion in the modeling and risk assessment of fire domino effects has hardly been taken into account. In the present study, the dynamic evolution of fire protection systems has been investigated qualitatively using event tree analysis. To quantify the temporal changes and their impact on the escalation of fire domino effects, a dynamic Bayesian network methodology has been developed. The application of the methodology has been demonstrated using an illustrative case study, considering a variety of fire scenarios, target installations, and firefighting systems.

Domino effects related to explosions in the framework of land use planning

Domino Effects Related to Explosions in the Framework of Land Use Planning Ernesto Salzano*, Giacomo Antonioni, Gabriele Landucci, Valerio Cozzani a Istituto di Ricerche sulla Combustione, CNR, Via Diocleziano n.328, 80124 Napoli, Italy. b Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali, Alma Mater Studiorum Università di Bologna, via Terracini n.28, 40131 Bologna, Italy c Dipartimento di Ingegneria Civile e Industriale, Università di Pisa, Via Diotisalvi n.2, 56126 Pisa, Italy. salzano@irc.cnr.it