Failure Modes and Effect Analysis FMEA

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. 

An FMEA team, usually put together for the purpose of the analysis, will work through a series of steps to apply the tool. At least one member of the team is usually an FMEA expert experienced in using the technique. A typical approach to an assessment might look like this  

For each function or process establish the ways in failure might occur. Each of these items represents a failure mode (see Sect. 6.3). 

For FEMCA, ascertain the severity, likelihood and detectability of the failure mode and use this to generate the Risk Priority Number (RPN) 

Rank the risks by RPN and use this as the basis for prioritising corrective actions 

A Failure Mode and Effects Analysis (FMEA) is a sequential analysis and evaluation of the kinds of failures that could happen and their likely effects, expressed in terms of maximum potential loss. The technique is used as a predictive model and forms part of an overall risk assessment study. This analysis is described completely in the MIL-STD-1629A. The FMEA is most useful in system hazard analysis for highlighting critical components (Ridley, 1994). 

In this method of analysis, the constituent major assemblies of the product to be analyzed are listed. Next, each assembly is broken into subassemblies and components. Each component is then studied to determine how it could malfunction and cause downstream effects. Effects might result on other components, and then on higher-level subassemblies, assemblies, and the entire product. Failure rates for each item are determined and listed. The calculations are used to determine how long a piece of hardware is expected to operate for a specific length of time. It is the best and principal means of determining where components and designs 

The FMEA is limited to determination of all causes and effects, hazardous or not. Furthermore, the FMEA does very little to analyze problems arising from operator errors or hazardous characteristics of equipment created by bad design or adverse environments. However, the FMEA is excellent for determining optimum points for improving and controlling product quality (Hammer, 1989). (An example of an FMEA for a bicycle can be found in figure 9-4.) 

A FHA is an inductive method for finding dangers that result from single-fault events (Roland and Moriarty, 1990). It identifies hazards during the design phase. The investigator takes a detailed look at the proposal system to determine hazard modes, causes of hazards, and the adverse effects associated with the hazards. 

An event, usually a malfunction, described in functional terms 

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Methods for performing hazard analysis and risk assessment include safety review, checkhsts, Dow Fire and Explosion Index, what-if analysis, hazard and operabihty analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. Other methods are also available, but those given are used most often. 

Failure Mode and Effects Analysis. The system design activity usually emphasizes the attainment of performance objectives in a timely and cost-efficient fashion. The failure mode and effects analysis (FMEA) procedure considers the system from a failure point of view to determine how the product might fail. The terms design failure mode and effects analysis (DFMEA) and failure mode effects and criticaUty analysis (EMECA) also are used. This EMEA technique is used to identify and eliminate potential failure modes early in the design cycle, and its success is well documented (3,4). 

Chrysler Corporation, Ford Motors, General Motors Corporation 1995 Potential Failure Mode and Effects Analysis (FMEA) - Reference Manual, 2nd Edition. 

A risk assessment analyses systems at two levels. The first level defines the functions the system must perform to respond successfully to an accident. The second level identifies the hardware for the systems use. The hardware identification (in the top event statement) describes minimum system operability and system boundaries (interfaces). Experience shows that the interfaces between a frontline system and its support systems are important to the system cs aluaiion and require a formal search to document the interactions. Such is facilitated by a failure modes and effect analysis (FMEA). Table S.4.4-2 is an example of an interaction FMEA for the interlace and support requirements for system operation. 

How do you then design an effective system There are several techniques you can use. Failure Modes and Effect Analysis (FMEA), Fault Tree Analysis (FTA), and Theory of Constraints (TOC) are but three. The FMEA is a bottom-up approach, the FTA a top-down approach, and TOC a holistic approach. 

There is one technique widely used in the automotive industry for detecting and analyzing potential nonconformities Failure Modes and Effects Analysis (FMEA). There are Design FMEAs and Process FMEAs. The technique is the same - it is only the focus that is different. As clause 4.14 addresses potential nonconformities, the subject of FMEAs is treated in Part 2 Chapter 14. 

Potential failure mode and effects analysis (FMEA) (GM, Ford, Chrysler)... 

Failure Modes and Effects Analysis (FMEA) A hazard identification technique in which all known failure modes of components or features of a system are considered in turn and undesired outcomes are noted. 

The what-if analysis is a creative, brainstorming examination of a process or operation conducted by a group of experienced individuals able to ask questions or voice concerns about undesired events. It is not as inherently structured as some other methods, such as the hazard and operability (HAZOP) study or a failure mode and effects analysis (FMEA). 

In the FMECA procedure [2,3,256], an exhaustive list of the equipment is first made. Every item on the list is then reviewed for possible ways in which it can fail (the failure modes are open, closed, leaks, plugged, on, off, etc.). The effects of each failure mode are then recorded and a criticality ranking of every item of equipment is calculated. A limitation of this procedure is that combinations of failures which may cause an incident are not really identified. Failure modes and effects analysis (FMEA) is the same procedure without the criticality analysis. 

Failure Mode and Effect Analysis (FMEA) This is a systematic study of the causes of failures and their effects. All causes or modes of failure are considered for each element of a system, and then all possible outcomes or effects are recorded (HEP Chaps. 4.8, 6.8, 19). 

Equilibrium state, 24 642. See also Equilibrium progress toward, 24 649 Equilibrium value, 14 611 Equilibrium volume parameters, from density measurements, 13 435-436 Equimolar counterdiffiision, 1 39-40 drift flux correction, 1 55-58 Equipment. See also Failure mode and effects analysis (FMEA)... 

Failure Modes and Effects Analysis (FMEA) Scenario- based Inductive By component Mechanical/electrical systems Best for analyzing effects of single failures, although capable of developing and analyzing multiple-safeguard scenarios Looks at all failure modes of all components Higher... 

Several qualitative approaches can be used to identify hazardous reaction scenarios, including process hazard analysis, checklists, chemical interaction matrices, and an experience-based review. CCPS (1995a p. 176) describes nine hazard evaluation procedures that can be used to identify hazardous reaction scenarios-checklists, Dow fire and explosion indices, preliminary hazard analysis, what-if analysis, failure modes and effects analysis (FMEA), HAZOP study, fault tree analysis, human error analysis, and quantitative risk analysis. 

The PHA procedure can be conducted using various methodologies. For example, the checklist analysis discussed earlier is an effective methodology. In addition, Pareto analysis, relative ranking, pre-removal risk assessment (PRRA), change analysis, failure mode and effects analysis (FMEA), fault tree analysis, event tree analysis, event and CF charting, PrHA, what-if analysis, and HAZOP can be used in conducting the PHA. 

Preliminary hazard analyses (PHAs) have been conducted for the SILVER II process at various stages of design and have served as building blocks for the EDP PHA effort (AEA, 2001a). These PHAs use the Failure Modes and Effects Analysis (FMEA) technique in accordance with the following regulations and standards ... 

Other examples of inductive tools that have limited application in incident investigation include failure mode and effects analysis (FMEA), hazard and operability study (HAZOP), and event tree analysis (ETA). These are detailed in the CCPS book, Guidelines for Hazard Evaluation Procedures... 

Risk assessment tools such as a nine-block risk assessment (Table 9) or a failure mode and effect analysis (FMEA) are available to assist the process owner with the evaluation of the process or issue to better understand and communicate the... 

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)... 

Inductive methods, such as check lists, Failure Mode and Effect Analysis (FMEA), event trees, decision tables, Analysis of Potential Problems (APP). These methods proceed from an initial cause of the deviation and construct a scenario ending with the final event. They are based on questions of the type What if ... 

The Failure Mode and Effect Analysis (FMEA) is based on the systematic analysis of failure modes for each element of a system, by defining the failure mode and the consequences of this failure on the integrity of that system. It was first used in the 1960s in the field of aeronautics for the analysis of the safety of aircraft [15]. It is required by regulations in the USA and France for aircraft safety. It allows assessing the effects of each failure mode of a system s components and identifying the failure modes that may have a critical impact on the operability safety and maintenance of the system. It proceeds in four steps ... 

In this first case, system security is associated with preventing the accidental or intentional alteration and corruption of the data to be displayed on the screen, or be used to make a decision to control the operation. To avoid accidental or intentional loss of data, the data collected must be defined, along with the procedures used to collect it, and the means to verily its integrity, accuracy, reliability, and consistency. A failure modes-and-effects analysis (FMEA) is one of many methods used to uncover and solve these factors. For example, to avoid data corruption, an ongoing verification program (Chapter 18) should be implemented. 

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