Identification hazard

For each process in a chemical plant the following questions must be asked  

The first question represents hazard identification. The last three questions are associated with risk assessment, considered in detail in chapter 11. Risk assessment includes a determination of the events that can produce an accident, the probability of those events, and the consequences. The consequences could include human injury or loss of life, damage to the environment, or loss of production and capital equipment. Question 2 is frequently called scenario identification. 

The terminology used varies considerably. Hazard identification and risk assessment are sometimes combined into a general category called hazard evaluation. Risk assessment is sometimes called hazard analysis. A risk assessment procedure that determines probabilities is frequently called probabilistic risk assessment (PRA), whereas a procedure that determines probability and consequences is called quantitative risk analysis (QRA). 

Hazards identification and risk assessment studies can be performed at any stage during the initial design or ongoing operation of a process. If the study is performed with the initial design, it should be done as soon as possible. This enables modifications to be easily incorporated into the final design. 

Hazard identification can be performed independent of risk assessment. However, the best result is obtained if they are done together. One outcome is that hazards of low probability and minimal consequences are identified and addressed with the result that the process is gold-plated. This means that potentially unnecessary and expensive safety equipment and procedures are implemented. For instance, flying aircraft and tornadoes are hazards to a chemical plant. What are the chances of their occurrence, and what should be done about them For most facilities the probability of these hazards is small No steps are required for prevention. Likewise, hazards with reasonable probability but minimal consequences are sometimes also neglected. 

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Fig. 1. Flow chart representing the complete hazard identification and risk assessment procedure.

Most hazard identification procedures have the capabiUty of providing information related to the scenario. This includes the safety review, what-if analysis, hazard and operabiUty studies (HAZOP), failure modes and effects analysis (FMEA), and fault tree analysis. Using these procedures is the best approach to identifying these scenarios. 

The remaining step in the hazard identification and risk assessment procedure shown in Figure 1 is to decide on risk acceptance. For this step, few resources are available and analysts are left basically by themselves. Some companies have formal risk acceptance criteria. Most companies, however, use the results on a relative basis. That is, the results are compared to another process or processes where hazards and risks are weU-characterized. 

Hazard identification involves gathering and evaluating data on the types of health injury or disease that may be produced by a chemical and on the conditions of exposure under which injury or disease is produced. It may also involve characterization of the behavior of a chemical within the body and the interactions it undergoes with organs, cells, or even parts of cells. Hazard identification is not risk assessment. It is a scientific determination of whether observed toxic effects in one setting will occur in other settings. 

Risk characterization is defined as the integration of the data and analysis of the above three components to determine the likelihood that humans wiU. experience any of the various forms of toxicity associated with a substance. When the exposure data are not available, hypothetical risk is characterized by the integration of hazard identification and dose—response evaluation data. 

Fire and Explosion Index (Ffrom fires and explosions. frequency The rate at which observed or predicted events occur. HAZOP HAZOP stands for hazard and operabihty studies. This is a set of formal hazard identification and ehmination procedures designed to identify hazards to people, process plants, and the environment. See subsequent sections for a more complete description. 

For a detailed description of the degrees of severity of the ratings, see NFPA 704. Table 26-4 shows the system for identification of hazards. Figures 26-1, 26-2, and 26-3 show examples of arrangements for display of the NFPA 704 Hazard identification System. 

Has an effective safety and health program (for example, safety procedures, training, hazard identification and analysis) been established to protect personnel on the work site, including employees and contractors If no, explain. 

Hazard identification builds the foundation on which subsequent quantitative frequency and/or consequence estimates are made. Many companies have been using the hazard identification techniques listed in Figure 7 for... 

The hazard identification step of the QRA typically requires the greatest involvement of plant personnel. For an existing process, only plant personnel know the status of process equipment and the current operating and maintenance practices. Excluding those personnel from the hazard identification step increases the chance of overlooking important potential hazards. For accurate results, the QRA team must have access to this information. 

The cost of performing the hazard identification step depends on the size of the problem and the specific techniques used. Techniques such as brainstorming, what-if analyses, or checklists tend to be less expensive than other more structured methods. Hazard and operability (HAZOP) analyses and failure modes and effects analyses (FMEAs) involve many people and tend to be more expensive. But, you can have greater confidence in the exhaustiveness of HAZOP and FMEA techniques—their rigorous approach helps ensure completeness. However, no technique can guarantee that all hazards or potential accidents have been identified. Figure 8 is an example of the hazards identified in a HAZOP study. Hazard identification can require from 10% to 25% of the total effort in a QRA study. 

The frequency analysis step involves estimating the likelihood of occurrence of each of the undesired situations defined in the hazard identification step. Sometimes you can do this through direct comparison with experience or extrapolation from historical accident data. While this method may be of great assistance in determining accident frequencies, most accidents analyzed by QRA are so rare that the frequencies must be synthesized using frequency estimation methods and models. 

Wells, G., Hazard Identification and Risk Assessment, Rugby, Warwickshire, UK Institution of Chemical Engineers, 1996. 

The acronym for chemical process quantitative risk analysis. It is the process of hazard identification followed by numerical evaluation of incident consequences and frequencies, and their combination into an overall measure of risk when applied to the chemical process industry. It is particularly applied to episodic events. It differs from, but is related to, a probabilistic risk analysis (PRA), a quantitative tool used in the nuclear industry... 

A hazard identification technique in which all known failure modes of components or features of a system are considered in turn, and undesired outcomes are noted... 

An elementary introduction to chemistry is given in Chapter 3 this serves only to provide background and for more advanced consideration reference will be necessary to specific text books, e.g. as listed in the Bibliography. A brief discussion of the relevance of physicochemical principles to hazard identification is given in Chapter 4. Relevant toxic and flammable properties, and summaries of appropriate precautions to cater for them during handling, use and disposal, are provided in Chapters 5 and 6, respectively. Reactive hazards are discussed in Chapter 7. The special problems with cryogenic materials and chemicals under pressure, typified by compressed... 

Section 2. Hazards Identification (assembling facility, transportation route, and chemical data) ... 

Handbook of Emergency Response to Toxic Chemical Releases HAZARDS IDENTIFICATION... 

SOPHIE Selection of Procedures For Hazard Identification and Evaluation Battelle Columbus Division 505 King Avenue Columbus, OH 43201-2693 (614) 424-6424 Assists users with selection of methods to employ for identifying and evaluating hazards in chemical and petrochemical facilities. 

The hazard identification step is perhaps the most important, because any hazard not identified will not be considered in the decision process. For example, the impact of chlorofluorocarbons on atmospheric ozone was unknown for much of the period of their use, and this potential hazard was not considered until recent years. 

The What if..method, the checklist, and HAZOP are well-publicized hazard identification tools. CCPS (1992) presents guidance on the use of these tools. 

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