Risk assessment preliminary hazard analysis

A designer, as part of his facility design analysis, should perform a hazards analysis or risk assessment of the various processes which will be conducted within the facility in order to determine what potential thermal dangers or threats exist to personnel and equipment. A hazards analysis or risk assessment will provide for the identification of potential hazards and of the necessary corrective actions/measures to prevent or control the hazard. Early in the design of a facility, the processes and equipment may be conceptual and at this stage, a preliminary hazards analysis can be performed. It is early in the design that a preliminary hazards analysis can be most helpful because its... 

Preliminary Hazard Analysis Description. The incorporation of this information into a PHA entry is shown as Table II. This entry describes the proposed actions needed to eliminate or control the hazard (column 6), the risk assessment code assigned after controls (column 7), and the identification of applicable codes and standards (column 8). 

For example, the hazard analysis and risk assessment requirements of the European Standard ISO 14121, Safety of Machinery—Principles for risk assessment (formerly EN 1050), have been adequately met in some companies in the design or redesign stages by applying an adaptation of the preliminary hazard analysis technique. 

Many hazard analysis and risk assessment techniques have been developed. These are just a few of the methodologies mentioned in the literature preliminary hazard analysis gross hazard analysis hazard criticality ranking catastrophe analysis change analysis energy flow/barrier analysis energy transfer analysis event tree analysis human factors review the hazard totem pole and double failure analysis. There are many other hazard analysis systems. 

System safety is hazards-focused, as are all the subsets of the practice of safety, whatever they are called. System safety commences with hazard identification and analysis. Do that poorly, and all that follows is misdirected. Applications of the hazard analysis and risk assessment methods developed in the evolution of system safety have been successful. The generalist in safety practice ought to know more about them. As a minimum, generalist safety practitioners should be knowledgeable about these methods Preliminary Hazard Analysis What-If Analysis and Failure Modes and Effects Analysis. (See Chapter 14, Hazard Analysis and Risk Assessment. )... 

A Brief Overview of Selected System Safety Analytical Approaches Working with the Risk Assessment Matrix Preliminary Hazard Analysis Energy Flow/Barrier Analysis Failure Modes and Effects Analysis Fault Tree Analysis... 

Preliminary hazard analysis is one of the early steps in a system safety project. This step also creates assessments of risks associated with each hazard. This step defines possible corrections for the risks. The product of this step is a tabular inventory of hazards for the system under consideration. The PHA fits best during early system stages, such as concept definition, design, and development. 

PRELIMINARY HAZARD ANALYSIS HAZARD ANALYSIS AND RISK ASSESSMENT... 

The original use of the preliminary hazards analysis (PHA) technique was to identify and evaluate hazards in the early stages of the design process. However, in actual practice the technique has attained much broader use. The principles on which preliminary hazards analyses are based are used not only in the initial design process, but also in assessing the risks of existing products or operations. 

A written communication accompanies the analysis, explaining the assumptions made and the rationale for them. Comments would then be made on the assignment of responsibilities for the remedial actions to be taken and when. A Hazard Analysis and Risk Assessment Worksheet (formerly called a Preliminary Hazard Analysis Worksheet) appears in Addendum A at the end of this chapter, courtesy of A-P-T Research, Inc. That form, and other similar forms, require entry of severity, probability, and risks codes before and after countermeasures are taken. 

R. H. Perry, Preliminary Hazard Analysis and Risk Assessment for Wood Centre Development,... 

As a practical matter, having knowledge of three risk assessment concepts will be sufficient to address most, but not all, risk situations. They are Preliminary Hazard Analysis and Risk... 

In ANSI/ASSE Z590.3—2011, the Prevention through Design standard, Addendum G comments on only eight hazard analysis and risk assessment techniques, intentionally. They are Preliminary Hazard Analysis, What-If Analysis, Checklist Analysis, What-If Checklist Analysis, Hazard and Operability Analysis, Failure Mode and Effects Analysis, Fault Tree Analysis, and Management Oversight and Risk Tree (MORT). It was also said in Z590.3 that ... 

The goal of risk analysis is to identify events that may have one or several undesirable consequences on a system, and to assess the likelihood and severity of these consequences. A lot of methods can be used to conduct risk analysis (Flaus, 2013a) such as Preliminary Hazard Analysis (PHA) and Failure Mode Effects Analysis (FMEA) (Papadopoulos et al., 2004). In most of these methods, the obtained information may be used to build a risk model. The next step after risk analysis is to study the behavior of the system, when the undesirable events occur, in order to evaluate its performance in degraded conditions, and its robustness or resilience. An approach to allow integrated risk analysis and simulation has been proposed for business process management (Tjoa et al., 2011). 

A large, deep cavern (formed from a salt dome) located north of Houston, Texas, has been proposed as an ultimate disposal site for both solid hazardous and municipal wastes. Preliminary geological studies indicate that there is little chance that the wastes and any corresponding leachates will penetrate the cavern walls and contaminate adjacent soil and aquifers. A risk assessment analysis was also conducted during the preliminary study and the results indicate that there was a greater than 99% probability that no hazardous and/or toxic material would meander beyond the cavern walls during the next 25 years. 

A formal hazard analysis of the anticipated operations was conducted using Preliminary Hazard Assessment (PHA) and Failure Modes and Effects Analysis (FMEA) techniques to evaluate potential hazards associated with processing operations, waste handling and storage, quality control activities, and maintenance. This process included the identification of various features to control or mitigate the identified hazards. Based on the hazard analysis, a more limited set of accident scenarios was selected for quantitative evaiuation, which bound the risks to the public. These scenarios included radioactive material spills and fires and considered the effects of equipment failure, human error, and the potential effects of natural phenomena and other external events. The hazard analysis process led to the selection of eight design basis accidents (DBA s), which are summarized in Table E.4-1. 

Very little real analysis is completed during the concept phase because analysis detail and data are generally not available. A preliminary risk assessment code (RAC) is determined, however, as part of the preliminary hazard list. This initial RAC is used to aid in determining the initial scope of the system safety effort and in the early evaluation of alternative designs and approaches. 

In the previous chapter, it was established that in industry, plant hazards can cause harm to property (plant—machinery, asset), people, or the environment. So, it is important to develop some means of analyzing these and come up with a solution. Unfortunately, it is not as straightforward as it sounds. There are plenty of plant hazard analysis (PHA) techniques and each of them has certain strengths and weaknesses. Also each specific plant and associated hazard has specific requirements to be matched so that hazard analysis will be effective. In this chapter, various hazards (in generic terms) will be examined to judge their importance, conditions, quality, etc. so that out of so many techniques available for PHA it is possible to select which one is better (not the best because that needs to be done by experts specifically for the concerned plant) suited for the type of plant. So, discussion will be more toward evaluation of PHA techniques. Some PHA is more suited for process safety management (PSM) and is sometimes more applicable for internal fault effects [e.g., hazard and operability study (HAZOP)]. In contrast, hazard identification (HAZID) is applicable for other plants, especially for the identification of external effects and maj or incidents. HAZID is also covered in this chapter. As a continuation of the same discussion, it will be better to look at various aspects of risk analysis with preliminary ideas already developed in the previous chapter. In risk analysis risk assessment, control measures for safety management systems (SMSs) will be discussed to complete the topic. 

Chapters 5 through 9 are the best sources for tools to identity risk in the system. Once the system is defined, developing a quick preliminary hazard list will detect the gross hazards of concern to the system. The hazard analysis further refines the hazard list and clearly recognizes which hazards are of greatest concern. Also, the Hazard Risk Index is a good qualitative tool with which to note some of the qualitative risks that are required in step 6 of the risk assessment methodology. 

In this paper, we propose a structured method based on UML environment models supported by a tool. We assume that an item definition, hazard analysis, risk assessment and safety goals according to ISO 26262 are given (see e.g. [2]). In this paper, we focus on the next step the creation of a functional safety concept (FSC) in which we show how the functional safety requirements are systematically derived. In the FSC, additionally, requirements may be decomposed in order to lower the ASIL. Furthermore, the functional safety requirements are allocated to elements of a preliminary architecture. These aspects are appropriately described in the ISO 26262 and need no further explanation and improvement and are, therefore, not part of this paper. The contribution of our paper can be summarized as follows ... 

As a result, a functional hierarchy develops in which malfunctions of the lower hierarchy influence the upper functional hierarchy. Similarly, within one horizontal functional level there are reciprocal influences. This is why a hierarchical function stmcturing is recommended before a hazard and risk analysis, in order to be able to describe potential malfunctions. Any changes of the functional architecture, their implemented environment and of course their characteristics, could lead to new or other malfunctions and consequently change the result of the Hazard Analysis and Risk Assessment. This is a further indication why in many industries the word preliminary is attributed to this analysis or mentioned in its name. 

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