Failures explosion relief

For some other types of emergency relief, such as dust explosion relief of relatively weak vessels, it is common practice to size the relief system to limit the pressure to that which will cause deformation but not failure of the vessel. If an explosion occurs, the deformed vessel can be replaced. Great care should be taken before applying such principles to pressure vessels for the following reasons ... 

Initiating events or major causes in both cases are plant failure e.g. equipment failure, process problems, material movement problems, control failure (ineffective loss prevention program, inadequate material evaluation). Major contributing factors or intermedidate events in this industry are formed by the human element, faulty design, long replacement times and inadequate explosion relief (Sam, 2005). 

At 2 20 A M., another explosion occurred, the BLEVE of sphere 407. Its fireball was less intense than the earlier one. The sphere s top section traveled 190 m (620 ft) and caused the destruction of a firewater tank and one of the plant s fire pumps. Other sections further damaged other units. The pressure relief valve of this sphere traveled 500 m (1600 ft). The damage from projectiles was much greater than that caused by the first sphere failure because they traveled farther and in more damaging directions. 

Relief valve or vent 8 explosion, 1 stopover, and 1 failure due to overheating... 

A-2.11.1 Storage Vessel Failure. The release of GH2 or LH2 may result in ignition and combustion, causing fires and explosions. Damage may extend over considerably wider areas than the storage locations because of hydrogen cloud movement. Vessel failure may be started by material failure, excessive pressure caused by heat leak, or failure of the pressure-relief system. 

Examples of common safe practices are pressure relief valves, vent systems, flare stacks, snuffing steam and fire water, escape hatches in explosive areas, dikes around tanks storing hazardous materials, turbine drives as spares for electrical motors in case of power failure, and others. Safety considerations are paramount in the layout of the plant, particularly isolation of especially hazardous operations and accessibility for corrective action when necessary. 

Plot the temperature-time trajectory up to a period of 120 min after the reactants were mixed and brought up to 175°C. Showthat the following three conditions had to have been present for the explosion to occur (1) increased ONCB charge, (2) reactor stopped for 10 min, and (3) relief system failure. 

Unless an event like a containment-internal explosion or fire is the cause, the release begins with a leak. The cause can be a failure of the containment (loss of containment LOG) or a planned relief via bursting discs or safety valves, unless they discharge into a receiving vessel. Erequent failure mechanisms and their expected frequencies of occurrence were already addressed in Sect 8.1. 

In the present case, uncertainty about the failure rates of the pumps, block valves, check valves and relief valves is represented using the lognormal probability distributions defined in the probabilistic approach, whereas the possibihly distributions introduced in the possibihstic approach are used to represent the uncertainty about the failure rates for the explosive valves and the tank. 

BLEVEs (Boiling Liquid Expanding Vapor Explosions) A pressurized tank of VCM or associated piping exposed to an external fire may fail due to metallurgical weakening. Such failure may result in a catastrophic tank failure, a fireball and the potential for rocketing fragments. Relief valve overpressure protection will not prevent a BLEVE. 

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