Failure Modes Effects Analysis scope

Once the scope of the analysis has been established, the FMEA can begin by examining the effects of specific failures in the system or subsystem. As these failures are identified, they are recorded on the Failure Mode Effect Analysis Worksheet (Figure 10.1) for evaluation. The completed FMEA will then be very useful in the performance of other system safety analyses such as an SHA or the SSHA. 

Failure Modes and Effects Analysis. Failure modes and effects analysis (FMEA) is applied only to equipment. It is used to determine how equipment could fail, the effect of the failure, and the likelihood of failure. There are three steps in an FMEA (4) (7) define the purpose, objectives, and scope. Large processes are broken down into smaller systems such as feed or cooling. At first, the failures are only considered to affect the system. In a more general study, the effects on a plant-wide basis can be considered. (2) Define the problem and boundary conditions. This includes identifying the system to be studied, establishing the physical boundaries, and labeling the equipment with a unique identifier for use in the FMEA procedure. (3)... 

XI. Preliminary Process Safety Studies A simple what-if study is generally performed to identify major safety concerns, if any, with the project scope. FMEA (failure modes and effects analysis) or HAZOP (Hazard and operability) study can also be performed if sufficient design documents are available. Otherwise, these detailed studies will be conducted in FEED. Necessary changes are made to the project scope for mitigating any significant process safety concerns. 

Step 1 scoping the Failure Modes and Effects Analysis... 

This is not a finite listing, as other, more complex approaches such as Managanent Oversight and Risk Tree Analysis (MORT), failure mode and effect analysis, and the aspects of system safety engineering are not covered within the scope of this book. These approaches can be found in many other books and articles. 

Formal analytical techniques such as failure modes and effects analysis, HAZOP and HAZAN are beyond the scope of this book. Contractors should not hesitate to ask their clients for assurance that these techniques have been used where the contractor has not been a party to the design process. 

Figure 21.2 illustrates how the starting point, the directions and the scope of each method fit into the accident-analysis framework of Chapter 6. Two of the methods. Fault tree analysis and Comparison analysis are deductive in that they start with the unwanted event. They proceed by analysing the underlying incidents and deviations (Fault tree analysis) or contributing factors (Comparison analysis). Several of the methods are mainly inductive in that they start with a deviation and proceed by studying the effects of this deviation. This applies to HAZOP, Failure mode and effect analysis. Event tree analysis and CRIOP, although they also have a component of causal analysis. Coarse analysis and Job-safety analysis start with the hazard and use a combination of inductive and deductive analyses. 

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