capitulo 3 metodos de identificacion de peligros

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3Hazard IdentificationMethods and Results

There are hazards associated with anyactivity, but analysts cannot begin to evaluatethem until they know what the hazards are. As defined previously, a hazard is aphysical or chemical characteristic of a material, system, process, or plant that hasthe potential for causing harm. Thus, hazard identification involves two key tasks:(1) identification of specific undesirable consequences and (2) identification ofmaterial, system, process, and plant characteristics that could produce thoseconsequences.The first task is relatively easy, but it is essential because it defines the scopeof the second task. Undesirable consequences can be broadly classified as humanimpacts, environmental impacts, or economic impacts. Within these broadclassifications, there may be specific consequence categories as illustrated in Figure3.1. Each of these categories can be further subdivided by the type of damage they

AdverseConsequences

HumanImpacts EnvironmentalImpacts EconomicImpactsProperty damageInventory lossProduction outagePoor product quality/yieldLost market share

Legal liabilityNegative image

Off-site contaminationairwatersoil

On-site contaminationairwatersou

Consumer injuriesCommunity injuriesOn-site personnel injuriesUnit personnel injuriesLoss of employmentPsychological effects

Figure 3.1 Adverse consequences resulting from process hazards.


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result in (e.g., toxic exposure, thermal exposure, overpressure, mechanical force,radiation, electrical shock). Thus, the more precisely the consequences of interestare defined, the easier it will be to identify hazards. For example, there may be athousand hazards with potential human impacts, but only tw o that could result inserious off-site injuries.Once th e consequences of interest are defined, th e analyst can identify thosesystem, process, and plant characteristics that could be a hazard of interest. It isessential that the hazard identification technique be thorough enough to identify allthe important hazards. However, if the approach does not provide somediscrimination between more important and less important hazards, then subsequenthazard evaluation attempts will be overwhelmed by the sheer number of potentialhazards to be examined. Common methods fo r hazard identification includeanalyzing process material properties and process conditions, reviewing organizationand industry process experience, developing interaction matrixes,and applying hazardevaluation techniques.

3.1 Analyzing Material Properties and Process ConditionsThere is a body of knowledge on which any proposed or existing process isbased. An important part of this process knowledge is data on all of the chemicalsused or produced in the process. This information is the foundation of all hazardidentification efforts.Typical material properties that are useful in hazard identification are listed inTkble 3.1. In addition to the information an organization has developed about a

specific material, there are many other public information resources (such as thoselisted in Tkble 3.2 and in the reference section of this chapter) that can provideinform ation about material properties.1"4 Some of the best resources are thechemical manufacturers and/or suppliers; they can provide product literature, accessto their chemical experts, and material safety data sheets (MSDSs). In addition,there may be a specific industrial group or association, like the Chlorine Institute,that will provide detailed information about safely handling specific types ofchemicals. Even if there is not a specific industrial group, there may be informationavailable from professional and industrial organizations like the American Instituteof Chemical Engineers, the American Petroleum Institute, or the ChemicalManufacturers Association.There are many published sources of chemical data. Dangerous Properties ofIndustrial Materials, Seventh Edition is one frequently used reference, as are thedatabases maintained by the Chemical Abstracts Service and the AIChE DesignInstitute for Physical Property Data (DIPPR).5"9 Government agencies and fundedorganizations like the U.S. Coast Guard, the Environmental Protection Agency, theFederal Emergency Management Agency, and the World Bank have also publishedchemical data.'11 Specific legal limits applicable to certain chemicals are includedin federal, state, and local legislation and regulations.12 An initial hazardidentification can be performed bysimply comparing the material properties availablefrom these diverse resources to the consequences of interest. For example, if ananalyst is concerned about the consequences of a fire, he or she can identify whichprocess materials are flammable or combustible. The analyst could then classify allof those materials as fire hazards and perform more detailed hazard evaluations.


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Tkbte3.1 Common Material Property Data for Hazard IdentificationAcute toxicity inhalation (e.g., LCLO) oral (e.g., LD50) dermalChronic toxicity

inhalation oral dermalCarcinogenicityMutagenicityTbratogenicityExposure limits

TLVPELSTELIDLHERPG

Biodegradability

Aquatic toxicityPersistence in the environmentOdor thresholdPhysical properties

freezing point coefficient of expansion boiling point solubility

Physical properties (cont'd)vapor pressuredensity or specific volumecorrosivity/erosivityheat capacityspecific heats

Reactivityprocess materialsdesired reaction(s)side reaction(s)decomposition reaction(s)kineticsmaterials of constructionraw material impuritiescontaminants (air, water, rust,lubricants, etc.)decomposition productsincompatible chemicalspyrophoric materials

Stability shock temperature light polymerization

Flammability/ExplosivityLEL/LFLUEL/UFLdust explosion parametersmi n i mum ignition energyflash pointautoignition temperatureenergy production

Process conditions also create hazards or exacerbate the hazards associated withthe materials in a process. For example, water is not classified as an explosionhazard based on its material properties alone. However, if a process is operated ata temperature and pressure that exceeds water's boiling point, then a rapidintroduction of water presents the potential for a steam explosion. Similarly,a heavyhydrocarbon m ay be difficult to ignite at ambient conditions, but if the process isoperated above the hyd rocarbon's flash point temperature,a spill of the material m ayignite. Therefore, it is not sufficient to consider only the material properties whenidentifying hazards; the process conditions must also be considered.


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Tkble3.2 Professional and Industry Organizations Offering Process SafetyEnhancement ResourcesOrgantTatinfl

ACSAmerican Chemical Society1155 16th St., N.W.Wishington, DC 20036(202) 872-4600

AIChEAmerican Institute of ChemicalEngineers345 E. 47th StreetNew York, NY 10017(212) 705-7338

AIHAAmerican Industrial Hygiene

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