Particular risk analysis hazard/event

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... 

An evaluation of both the frequency and the consequences of potential hazardous events to make a logical decision on whether the installation of a particular safety measure can be justified on safety and loss control grounds. Frequency and consequences are usually combined to produce a measure of risk, which can be expressed as the average loss per year in terms of injury or damage arising from an incident. The risk calculations of different design alternatives can be compared to determine the safest and most economical options. Calculated risk may be compared to set criteria that have been accepted by society or required by laws. See also Qualitative Risk Analysis. 

A SAC must be formulated if a safety risk occurs as a result of a regulation being ignored by the user, stipulated in a handbook (e.g. Operation Manual or Maintenance Handbook). The evaluation of the risk may resuit directly from the standards (e.g. demands for channel separation), or the gravity and the frequency of the particular case must be evaluated. In the best case, the degree of risk of the event which requires certain application rules should be examined within the scope of a hazard analysis. SACs should only be generated if the safety aim would fail without it. 

Safety-in-use considers that the intended function since it operates or behaves correct doesn t lead to any harm. The classical failure analyses cannot be considered for this analysis. Therefore, we rely on the positive analyses. In this case, particularly the behaviors of the intended functions, within its typical environment have to be analyzed as a positive approach. Generally, in this context we would see the classical event tree analysis (ETA). Based on deductively determined malfunctions and, in opposite to the general Hazard Risk Analysis according to ISO 26262, effects of intended functions, within relevant critical driving situations. 

Risk involves the combination of frequency and severity. Frequency considers the likelihood that a hazard will lead to an undesired event, incident, or accident. Severity deals with the extent of damage, injury, or harm. Both qualitative and quantitative approaches may be used in risk analysis. The topic of risk is covered in more detail elsewhere in this book. In general, the goal is to decide which hazards are most in need of controls. Clearly, those hazards that have both high frequency and high severity require the greatest attention. Ideally, aU hazards should be eliminated or reduced, but that is not always practical or financially feasible. Risk analysis techniques have been expanded over time for particular classes of hazards and particular methods may be called for in certain cases. Risk analysis is a very important part of the process of hazard recognition, evaluation, and control. 

The HSE expresses risk as "the likelihood that the harm from a particular hazard is realised." (para 5 (b)) Health and Safety Commission (1992) Management of Health and Safety at Work 1992 Approved Code of Practice. London HMSO. The Royal Society expresses risk as "the probability that a specified undesirable event will occur in a specified period or as a result of a specified situation." Royal Society Study Group (1992) Risk Analysis, perception and management. London Royal Society. Grimaldi and Simmonds (1984) Safety management. USA RD Irwin, express risk as "the assumed effect of an uncontrolled hazard, appraised in terms of the probability it will happen, the maximum severity of any injuries or damages, and the public s sensitivity to the occurrence." pp 181. 

Bow tie analysis is a tool that has become very popular in the last few years, especially because of the ease in which it can display cause-consequence of a particular hazardous condition. It is a qualitative tool that combines the fault tree to determine the causes and how the fault could occur, with the event tree, which documents the consequence of the hazardous condition. It became much better known in the mid-1990s when Royal Dutch/Shell used it to better understand the Piper Alpha disaster. The process industry uses it not only to assess the hazards and risks but also as a very effective communication tool to illustrate the cause-consequence-control and how it can impact a hazardous condition. In reality, it really isn t a new analytical tool, but rather, a very good visualization tool. 

An in-depth assessment from first principles and a cost-benefit analysis are not needed for every job. The extent of consideration should match the nature of the hazard and the extent and uncertainty of the risk and the measures necessary to avert it. In many cases it will be sufficient to identify and comply with the appropriate regulations. However, with hindsight (e.g. after an event) others may challenge actions/ decisions, and an engineer may have to establish the facts in the face of a hostile situation. Ultimately, a decision may have to be defended on judgement and so, particularly where decisions or recommendations are finely balanced, the consideration should be documented and, if possible, corroborated. 

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