FMECA Example

Suppose the failure consequence probabilities for the failure inodes in Table 3.6 are 20%, 100%, 20%, 10% and 30%, respectively. The duration of interest is 10,000 hours. Formulate the criticality matrix of the above system. 

From Table 3.6, it can be seen that failure mode 2 is classified as severity class 1, failure mode 3 as severity class 2 and failure mode 1 as severity class 2 while failure modes 4 and 5 are classified as severity class 4. 

If the criticality matrices for other systems are produced, comparisons can be made to determine which system needs more attention in the design stages. 

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From this assessment Table 3 can then be used to determine the level and frequency of testing. From the example of FMECA in Table 4, the following actions should be performed ... 

Section 13.3 outiines the principles of modeling packaging and food, using two simple but effective examples. They illustrate the concepts of critical steps, or materials or substances critical for food safety via a quantitative failure mode, effects and criticahty analysis (FMECA) approach, derived from concepts used by the aviation or electronic industry for critical systems. It is a systematic approach which today facilitates the risk management at the sector scale, of several thousand references or complex assemblies integrating various materials and dozens of substances [NGU13] via an expert distributable and modifiable system FMECAengine [VIT 11b]. 

Table 5.1 Example format for a system level 2 piece-part FMECA... 

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. 

In order to facihtate the understanding of the approach, two examples are provided to illustrate the main steps of the structural safety study. It will present how relevant parameters can be identified by means of theoretical approach hke FMECA, safety margin analysis, failure probabUity etc. These relevant parameters, say the drivers of the structural safely, will be taken into account and monitored in the manufacturing process through inspechons, control, and recording. This will enable to ensure that these parameters wiU not be missed with a probability equivalent to the safety and/or rehabihty target specified in the theoretical requirements. 

An example of FMECA worksheet covering some of the failure modes of fuel distribution system boost pump is given in Figure 5. 

In order to compare the results of LARA with well-established risk management methods, two examples were selected one from the University of Pardubice and one from EPFL. To have a variety of laboratory tasks, both chemical experiments and routine tasks were considered in the comparison. The first example was analyzed using the LARA method and a HAZOP procedure, whereas the second example was analyzed using the LARA method and the FMECA procedure. Both of these risk analysis procedures are widely acceptedtools to identify and manage risks (Bluvband et al. 2004). 

Table 3. Comparison of the risk priorities in example 2 using LARA and FMECA method.

Figure 2.22 shows an example FMECA worksheet form that is typically used. The form can be modified to suit the needs of a particular program. 

In the following sections, examples of the application of FMECA and HAZOP to two functional components will be described. The first component involves sample handling, the second the performance of the computer system file server. 

In this section, the qualitative analysis aimed at identifying the hazards and failure mechanisms associated to the operation of a system is exemplified by way of a very common method known as failure mode and effects analysis (FMEA). Actually in practice, a FMECA (failure mode, effects, and criticality analysis) is typically performed to arrive at also assigning a criticality class to each failure mode, for example, according to the following ranking ... 

A large number of measurement and decision-making tools (to define what should be prioritised in a safety action plan) were developed in the 1980s some versions of these became much more forward-looking at the design stage (for example HAZOP), while others added dimensions of the basic calculation process (FMECA calculates risk as frequency multipled by seriousness multipUed by detectabiUty). 

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