FMEA/FMECA methodology

Like HAZOP, here also a team is entrusted to carry out the study. Another important point to be remembered is that this is usually a live document so that any changes, etc. that can affect safety/risks can be reassessed with the help of the analysis. So it is not a case of once it is done the responsibility is over it needs to be updated. FMEA/FMECA methodology is presented in Figs. IV/2.1-1 and IV/2.1-2. It is worth noting that these two drawings should be viewed in conjunction, as one is related to the other. Fig. IV/2.1-3 is presented to depict PFMEA and its relation with DFMEA. 

Failure Mode and Effects (and Criticality) Analysis (FMEA/FMECA) are structured methodologies for the identification and analysis of the effects of latent equipment failure modes on system performance. This is a bottom-up process starting with the failure of a constituent/subsystem and investigating the effect of this on the system. It should be conducted by a team of experts with cross-functional knowledge of the analysed system, process or product. The methodology consists of the following steps ... 

FMEA is a prospective hazard analysis technique which is widely used in many domains and increasingly in the service industries [4]. The methodology has its origins in military systems and the aerospace industry in the 1960s. Subsequently the automotive and chemical engineering sectors adopted the tool - indeed in some regulated industries application of the technique is now mandatory. The objective of the tool is to identify what in a product can fail, how it can fail, whether failure can be detected and the impact that will have. The technique can be supplanented with a Criticality Analysis which takes into account the severity of the failure. When this extension is employed, the technique is often called FMECA. 

FMEA and FMECA analysis present some important limits, mainly related to RPN evaluation. Many authors have developed different methodologies in order to overcome these disadvantages and improve the failure mode prioritization process, most of them using a fuzzy approach. 

Fault trees, failure modes and effects analysis (FMEA), failure modes effects and criticality analysis (FMECA) and event trees use logic, reliability data (component failure rates), and assessed system failure rates, combined with human error failure rates (using methodologies such as HEART or THERP) and other methodologies such as software reliability assessment, to develop estimates of system failure frequencies, and hence plant accident frequencies. 

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