Hazard Analysis HAZAN

on the other hand, is a process to assess the probability of occurrence of such accidents and to evaluate quantitatively the consequences of such happenings, together with value judgments, in order to decide the level of acceptable risk. HAZAN is also sometimes referred to as Probabilistic Risk Assessment (PRA) and its study uses the well-established techniques of Fault Tree Analysis and/or Event Tree Analysis  

A HAZOP study is cumbersome and time-consuming. However, it is believed that the outcome of a perfectly carried out HAZOP study is that no HAZAN (or PRA) study is needed. 

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Hazard analysis (HAZAN) is a quantitative way of assessing the likelihood of failure. Other names associated with this technique are risk analysis, quantitative risk assessment (QRA), and probability risk assessment (PRA). Keltz [44] expressed the view that HAZAN is a selective technique while HAZOP can be readily applied to new design and major modification. Some limitations of HAZOP are its inability to detect every weakness in design such as in plant layout, or miss hazards due to leaks on lines that pass through or close to a unit but cany material that is not used on that unit. In any case, hazards should... 

Hazard and risk analysis is a vast subject by itself and is extensively covered in the literature [22]. In order to plan to avoid accidental hazards, the hazard potential must be evaluated. Many new methods and techniques have been developed to assess and evaluate potential hazards, employing chemical technology and reliability engineering. These can be deduced from Fault Tree Analysis or Failure Mode Analysis [23], In these techniques, the plant and process hazard potentials are foreseen and rectified as far as possible. Some techniques such as Hazards and operability (HAZOP) studies and Hazard Analysis (HAZAN) have recently been developed to deal with the assessment of hazard potentials [24]. It must be borne in mind that HAZOP and HAZAN studies should be properly viewed not as ends in themselves but as valuable contributors to the overall task of risk management... 

After the serious hazards have been identified with a HAZOP study or some other type of qualitative approach, a quantitative examination should be performed. Hazard quantification or hazard analysis (HAZAN) involves the estimation of the expected frequencies or probabilities of events with adverse or potentially adverse consequences. It logically ties together historical occurrences, experience, and imagination. To analyze the sequence of events that lead to an accident or failure, event and fault trees are used to represent the possible failure sequences. 

The engineering aspect regarding environmental protection and safety are specialised topics that cannot be treated properly here. As general introduction in environmental engineering we recommend the book of Allen and Rosselot (1996). In the field of process safety the book of Growl and Louvar (1989) is very popular. The topics of hazard and operability (Hazop), as well as hazard analysis (Hazan) are covered in a book due to Kletz (1992). A concise presentation of these issues sufficient for a student project may be found in Coulson Richardson vol. 6 (Sinnott, 1993). 

References 77 and 78 review some of the procedures developed for identifying plant hazards systematically. Among the better known are the hazard and operability study (Hazop), a qualitative technique based on the piping and instrumentation diagram, and hazard analysis (Hazan), used to quantify... 

If the consequences of failure are serious then we need a way of assessing the likelihood of the failure. The techniques used for this are known collectively as hazard analysis (Hazan), and their use requires expert advice. 

Hazard Analysis (HAZAN), analysing the effects of possible faults. 

However, anyone involved with actual design work soon realizes that there are in fact many choices to be made in arriving at a safe design, and that in reality nothing is 100 per cent safe not even total inactivity, of whose harmful consequences we are all aware The safety implications of plant design choices are, in principle, quantifiable. The techniques for doing this are usually described as hazard analysis (Hazan). 

Several methods are available for identifying and assessing hazards (Kletz, 1990). Hazards can be identified through checklists, failure mode effect analysis (FMEA), fault tree analysis, event tree analysis, what-if analysis, and hazard and operability studies (HAZOP). Assessing hazards can be done through hazard analysis (HAZAN), codes of practice, the Dow Explosion Index, and prototype index of inherent safety (PIIS). 

Stage (c) - Consequences of undesired event occurring Initially a hazard analysis (HAZAN) is undertaken so as to ascertain the magnitude of the potential problem and its potential for harm to the people, plant, process and the public. 

On the basis of the hazard analysis (Hazan) [39,40], the mathematical formula for the hazard rate H caused by failure of the protective system is given by... 

A small team, similar to that used in HAZOP, carries out hazard analysis. The three steps in HAZAN are ... 

As described earlier, a HAZOP hazard and operability study) is a technique used to identify process hazards and obstacles to the efficient operation of industrial facilities. It provides a systematic approach to quantifying hazard potentials. A HAZAN hazard analysis) is a technique for quantitative evaluation after a serious hazard has been identified or after an accident has occurred. 

For the most rigorous examination each event in the fault tree can be given a probability, allowing the total frequency of the final event to be calculated. This is the technique of hazard analysis or Hazan. 

Several risk indices have been practiced by the chemical and manufacturing industries over the past 50 years (see Table 8.5) (Heikkila, 1999). The important ones among these indices are the Dow Fire and Explosion Index, the Dow Chemical Exposure Index, the HAZAN (Hazard Analysis), and the Prototype Index of Inherent Safety. 

All employed dryers must be equipped with clear and comprehensive operating manuals prepared jointly by the equipment supplier and the plant operating management. The manual should be learned by the operators, who are to be trained in recognition of hazardous situations and risk assessment with the material being dried. Very useful techniques, known as Hazop (hazard and operability studies) and Hazan (hazard analysis), may be applied successfully in both new and existing processing plants [39,40]. 

HAZAN An abbrovialion for hazard analysis, it is a technique used to assess the probability of a hazard occrrrring and for determining the subsequent consequences. 

Hazard analysis. The concept of hazard analysis (or HAZAN) is widely used in the UK chemical industry and is a recognized part of the approach to the Ck>ntrol of Industrial Major Accident Hazard Sites or CIMAH legislation. 

The second benefit of hazard analysis is the guidance it provides in selecting appropriate improvement measures. If there are a variety of possible causes of a hazardous event, coupled with a number of protective measures, some of which are only applicable to specific causes, the HAZAN assists the Management in clarifying which factors make the most significant contribution to the overall risk level. 

In carrying out a hazard analysis, the event being considered needs to be specified. The HAZAN provides a measure of risk of that specified event occurring. The units of this measure are per year (i.e., it is a frequenQr of occurrence). The event considered for Teesside Power Station was ignition of a flammable vapor resulting in an explosion whilst an operator is present inside the enclosure. ... 

Isshiki, K. and Munesawa, Y and Nakai, A. and Suzuki. K., 2013. HAZOP Analysis System Compliant with Equipment Models based on SDG. Recent Trends in Applied Artificial Intelligence 460-469. Kletz, T.A., 1992. Hazop and Hazan Identifying and Assessing Process Industry Hazards Third Edition, Bristol. 

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