Chemical Process Accidents

Propagation - the event or events that maintain or expand the accident. 

Termination - the event(s) that stop the accident or diminish it in size. 

Initiation was the worker tripping propagation was the valve breaking, followed by 

Propagation Minimize Hazardous Materials, and Flammable Quantities, Maximize Use of Non-flammable, Equipment Spacing, and [nstail Check and Emergency Shutoffs. 

Termination Have Firefighting Equipment and Procedures, Relief and Sprinkler Systems. 

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Hazards from combustion and runaway reactions play a leading role in many chemical process accidents. Knowledge of these reactions is essential for control of process hazards. It is important that loss of containment be avoided. For example ... 

Loss of containment due to mechanical failure or misoperation is a major cause of chemical process accidents. The publication. One Hundred Largest Losses A Thiiiy Year Review of Propeity Damage Losses in the Hydrocarbon Chemical Industry, 9th ed. (M M Protection Consultants, Chicago), cites loss of containment as the leading cause of property loss in the chemical process industries. 

The previous chapter described the consequences of a nuclear reactor accident. Chemical process accidents are more varied and do not usually have the energy to melt thick pressure vessels and concrete basemats. The consequences of a chemical process accident that releases a toxic plume, like Bhopal did, are calculated similarly to calculating the dose from inhalation from a radioactive plume but usually calculating chemical process accidents differ from nuclear accidents for which explosions do not occur. 

The chemical and physical phenomena involved in chemical process accidents is very complex. The preceding provides the elements of some of the simpler analytic methods, but a PSA analyst should only have to know general principles and use the work of experts contained in computer codes. There are four types of phenomenology of concern 1) release of dispersible toxic material, 21 dispersion of the material, 3) fires, and 4) explosions. A general reference to such codes is not in the open literature, although some codes are mentioned in CCPS (1989) they are not generally available to the public. 

CCPS, Guidelines for Investigating Chemical Process Accidents (New York American Institute of Chemical Engineers, 1992). 

THE PRINCIPAL REASON FOR MOST CHEMICAL PROCESS ACCIDENTS... 

Ask any group of people experienced in chemical plant operations what causes most chemical process accidents, and you will get a variety of answers including operator error, equipment failure, poor design, act of God, and bad luck. However, in the opinion of representatives of many of the large chemical and oil companies in the United States, these answers are generally incorrect. The Center... 

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