Tank rupture

This chapter shows that chemical process systems may fail and have serious consequences to the workers, public and the environment. Comparing with Chapter 6, chemical processes are similar to the processes in a nuclear power plant, hence, they may be analyzed similarly because both consist of tanks, pipes heat exchangers, and sources of heat. As an example of analysis, we analyze a storage tank rupture. 

The fault tree (Figure 7.4-1) has "Pre.ssure Tank Rupture" as the top event (gate G1). This may result from random failure of the tank under load (BEl), OR the gate G2, "Tank ruptures due to overpressure" which is made of BE6 "Relief valve fails to open" AND G3, "Pump motor operates too long." This is made of BE2, "Timer contacts fail to open," AND G4, "Negative feedback loop inactive" which is composed of BE3, "Pressure gauge stuck," OR BE4, "Operator fails to open switch," OR "BE5, "Switch fails to open,"... 

Applying FTAPSUIT Chemical Process Tank Rupture... 

Fiy.ii r. 7.4-6 Monte Carlo Calculation of the Chemical Process Tank Rupture... 

After delivery, the driver disconnected the transfer lines, stepped into the cab of the truck, and began to maneuver the truck in the yard of the hospital. The truck tank ruptured, and the remaining contents of the tank were spewed into the area around the truck. Vigorously burning fires started in the oxygen-enriched atmosphere. 

Boiling-liquid expanding-vapor explosion (BLEVE) A BLEVE occurs if a vessel that contains a liquid at a temperature above its atmospheric pressure boiling point ruptures. The subsequent BLEVE is the explosive vaporization of a large fraction of the vessel contents possibly followed by combustion or explosion of the vaporized cloud if it is combustible. This type of explosion occurs when an external fire heats the contents of a tank of volatile material. As the tank contents heat, the vapor pressure of the liquid within the tank increases and the tank s structural integrity is reduced because of the heating. If the tank ruptures, the hot liquid volatilizes explosively. 

For jet fuel the energy of explosion is 18,590 Btu/lb and the molecular weight is 160. 6-30. You have decided to purchase a 500-gal tank of liquid propane (C3H8) to heat your house during the winter. You are concerned about tank rupture and the possibility of a vapor cloud explosion of all the propane. How far away (in ft) must the tank be from the house to ensure that your house will receive only minor damage from an explosion The specific gravity of liquid propane is 0.500, and the energy of explosion for propane is 503.9 kcal/g-mol. 

A process storage tank contained 6500 gal of ethylene oxide. It was accidentally contaminated with ammonia. The tank ruptured and dispersed ethylene oxide into the air. A vapor cloud was formed and almost immediately exploded. It created an explosive force equivalent to 18 tons of TNT, as evidenced by the damage. The events happened so rapidly that personnel could not take appropriate cover. One person was killed and nine were injured property losses exceeded 16.5 million. 

Acrylic monomers, in particular, are inclined to polymerisation in the absence of oxygen which serves as a chain-breaker in their radical polymerisation. Most such monomers are also flammable and may therefore be directed to be stored under a nitrogen blanket. If nitrogen purging is complete, the risk of fire within vessels may be zero, but the risk of explosive polymerisation, tank-rupture and external fire is increased. Some suspect that accidents of this type have occurred already [6],... 

Presence of mineral or Lewis acids, or bases including amines, will catalyse violent polymerisation of this very reactive dimer, accompanied by gas evolution [1], Sodium acetate is sufficiently basic to cause violent polymerisation at 0.1% concentration when added to diketene at 60°C [2]. A Russian paper describing a tank rupture incident triggered by ingress of acetic acid and pyridine, with suggested precautions against recurrence, is abstracted [3]. 

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