Risk assessment methods FMECA

Technology assessment (Westrum 1991) aims considering the potential consequences of new technological system. Several methods and tools exist to support such assessment. In the context of safety and security, brainstorming, expert groups and traditional risk assessment methods such as FMECA (Failure Mode, Effects and Criticality Analysis) are often used with the purpose of identifying potential risks related to the adoption of a new technology. 

From those techniques given in Table 1 my personal preference is for failure mode, effects, and criticality analysis (FMECA). This technique can be applied to both equipment and facilities and can be used to methodically break down the analysis of a complex process into a series of manageable steps. It is a powerful tool for summarizing the important modes of failure, the factors that may cause these failures, and their likely effects. It also incorporates the degree of severity of the consequences, their respective probabilities of occurrence, and their detectability. It must be stressed, however, that the outcome of the risk assessment process should be independent of the tool used and must be able to address all of the risks associated with the instrument that is being assessed. 

HSE assessments have a long tradition within the oil-and gas industry. These assessments use a wide range of methodologies, from the strict quantitative methods such as QRA (Quantitative Risk Analysis) and FMECA (Failure Mode Effect and Criticality Analysis) to the more qualitative methods such as HAZOP (HAZard OPerability analysis). Most methods combine qualitative and quantitative data and approaches. For example, an FMECA basically uses generic failure data, expert judgments are likewise important. 

Used originally as a reliability tool, the FMEA is now often used to identify and prioritize safety problems associated with hardware failures. This is usually done by including a risk assessment code (RAC) in the analysis (Table 14-1). (Note When a RAC or other method of quantifying is used to identify critical safety items, some organizations and analysts call the technique failure mode and effects criticality analysis [FMECA].)... 

Risk assessment. Traditional risk assessment processes based on different methods (FMECA, HAZOP, THERP, CREAM, etc.). 

The assembly process (Figure 10-1) brings together all of the assessment tasks to provide the risk, its significance, how it was found, its sensitivity to uncertainties, confidence limits, and how it may be reduced by system improvements. Not all PSAs use fault trees and event trees. This is especially true of chemical PSAs that may rely on HAZOP or FMEA/FMECAs. Nevertheless the objectives are the same accident identification, analysis and evaluation. Figure 10-1 assumes fault tree and event tree techniques which should be replaced by the equivalent methods that are used. 

A methodical examination of a process, plant and procedure which identifies hazards, assesses risks and proposes measures which will reduce risks to an acceptable level. (May use inter alia Hazops. Fault Tree Analysis, Check-lists, Event Tree Analysis. FMECA, etc). 

In this section, the Method for Error Deduction and Incident Analysis (MEDIA) methodology is applied to human and organizational factors assessment. A combination of Failure Mode, Effects and Criticality Analysis (FMECA) and MEDIA will be presented for pigging operations. Risk quantification of this assessment is based on the results of statistical analysis of past accidents as explained in section 2. 

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