Failure Modes Effects Analysis identification

Firstly the chapter approaches risk management in a general sense, including the phases of risk assessment (risk identification, risk analysis and risk evaluation), risk control (risk reduction or mitigation, and risk acceptance), risk documentation and communication, and risk review. Then some methods for risk assessment are explored further, such as matrix type and Failure Mode Effect Analysis (FMEA) using risk priority numbers (RPN). 

FMEA is an analytical method used to identify potential problems in the product and in its process of development. It is an inductive method used for identification of hazards of a system with single point failure. When criticality analysis is added with FMEA it is known as failure mode effect and criticality analysis (FMECA). It was used as early as 1950 in reliability engineering. FMEA/FMECA is mainly used for manufacturing, product development, etc. 

Failure Mode and Effects Analysis (FEMA)—FEMA is a tabulation of facility equipment items, their potential failure modes, and the effects of these failures on the equipment or facility. Failure mode is simply a description of what caused the equipment to fail. The effect is the incident, consequence, or system response to the failure. It is usually depicted in tabular format and expresses failures in an annual estimation. A FEMA is not useful for identifying combinations of failures that can lead to incidents. It may be used in conjunction with other hazard identification techniques such as HAZOP for special investigations such as critical or complex instrumentation systems. There is also a Failure Modes, Effects, and Criticality Analysis (FMECA), which is a variation of FMEA that includes a quantitative estimate of the significance of the consequence of a failure mode. 

This entry contains some basic concepts, general knowledge, and classical methods for the analysis of the reliability of structures, equipment, and systems and its quantitative estimation. The presentation of the subject matter follows the two phases typically used in practice for the implementation of the analysis the phase of qualitative analysis for hazards and failure modes identification and the phase of quantitative estimation of the reliability characteristics of interest. The concepts and practices of the first phase are exemplified via the common method of systematic analysis known as the failure mode, effects, and criticality analysis (FMECA). The mathematical, probabilistic concepts necessary... 

Most hazard identification procedures have the capabiUty of providing information related to the scenario. This includes the safety review, what-if analysis, hazard and operabiUty studies (HAZOP), failure modes and effects analysis (FMEA), and fault tree analysis. Using these procedures is the best approach to identifying these scenarios. 

Eailure Mode and Effects Analysis (EMEA) A failure identification methodology where the failure modes of a component sub-system are identified. An analysis of these failure modes on the safety of the entire system is performed. 

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. 

A failure modes and effects analysis delineates components, their interaction.s ith each other, and the effects of their failures on their system. A key element of fault tree analysis is the identification of related fault events that can contribute to the top event. For a quantitative evaluation, the failure modes must be clearly defined and related to a numerical database. Component failure modes should be realistically and consistently postulated within the context of system operational requirements and environmental factors. 

The lists of critical items that were described under Identifying controls in Part 2 Chapter 2, together with Failure Modes and Effects Analysis and Hazard Analysis, are techniques that aid the identification of characteristics crucial to the safe and proper functioning of the product. 

All of these factors determine the stress experienced by the workers and the extent to which operational errors will be recovered before disastrous consequences have ensued. In this context, hazard identification techniques, such as hazard and operability studies (HAZOP), failure modes and effects and criticality analysis (FMECA), fault trees, and others are useful in making the process environment more forgiving. 

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. 

Identification can be as simple as asking what-iP questions at design reviews. It can also involve the use of a checklist outlining the normal process hazards associated with a specific piece of equipment. The major weakness of the latter approach is that items not on the checklist can easily be overlooked. The more formalized hazard-assessment techniques include, but are not limited to, hazard and operability study (HAZOP), fault-tree analysis (FTA), failure mode-and-effect analysis (FMEA), safety indexes, and safety audits. 

System safety is hazards-focused, as are all the subsets of the practice of safety, whatever they are called. System safety commences with hazard identification and analysis. Do that poorly, and all that follows is misdirected. Applications of the hazard analysis and risk assessment methods developed in the evolution of system safety have been successful. The generalist in safety practice ought to know more about them. As a minimum, generalist safety practitioners should be knowledgeable about these methods Preliminary Hazard Analysis What-If Analysis and Failure Modes and Effects Analysis. (See Chapter 14, Hazard Analysis and Risk Assessment. )... 

A formal hazard analysis of the anticipated operations was conducted using Preliminary Hazard Assessment (PHA) and Failure Modes and Effects Analysis (FMEA) techniques to evaluate potential hazards associated with processing operations, waste handling and storage, quality control activities, and maintenance. This process included the identification of various features to control or mitigate the identified hazards. Based on the hazard analysis, a more limited set of accident scenarios was selected for quantitative evaiuation, which bound the risks to the public. These scenarios included radioactive material spills and fires and considered the effects of equipment failure, human error, and the potential effects of natural phenomena and other external events. The hazard analysis process led to the selection of eight design basis accidents (DBA s), which are summarized in Table E.4-1. 

A type of safety identification review that methodically analyzes the interactions between individuals and machines. It reviews the operation phase to operational phase, while considering the consequences of operator-system faults at each operating step within each phase. This analysis allows for the recognition of threats from equipment faults that may coexist with operator errors. It is considered similar to a Failure Mode and Effects Analysis (FMEA), but with increased emphasis on the steps in human procedures rather than viewing hardware exclusively. See also Failure Mode and Effects Anafysis (FMEA) Job Safety Analysis (JSA). 

The hazard identification and evaluation of a complex process by means of a diagram or model that provides a comprehensive, overall view of the process, including its principal elements and the ways in which they are interrelated. There are four principal methods of analysis failure mode and effect, fault tree, THERP, and cost-benefit analysis. Each has a number of variations, and more than one may be combined in a single analysis. See also Cost-Benefit Analysis Failure Mode and Effects Analysis (FMEA/FMECA) Fault Tree Analysis (FTA) THERP (Technique for Human Error Rate Probability). 

Step 5 is concerned with developing a list of crihcal items. The list is prepared to facilitate the communication of important analysis results, generally to the management personnel, and it contains information on areas such as item identification, concise statement of failure mode, criticality classification, and degree of loss effect. Finally, Step 6 is concerned with documenting the analysis. This step is equivalent in importance to all the previous steps (i.e., Step 1 to Step 5) because poor documentation can result in ineffectiveness of the FMEA process. The FMEA report includes items such as system description, ground rules, system definition, failure modes and their effects, and critical items list. 

Reliability, Maintainability, and Quality Control. Inclusion of these organizations in the system safety process, from concept through disposal, will aid in the identification of safety-critical components for reliability analysis. A failure mode(s) and effect(s) analysis (FMEA), as well as other common reliability models, can be used to identify critical and noncritical failure points. The quality assurance element can be extremely usefid in the overall system safety process. Quality engineers should participate in the inspection of safety-critical components, serve on certification boards, audit any corrective-action requirements, and identify any safety impacts associated with implementation of such requirements. 

The SSHA evaluates hazardous conditions, on the subsystem level, which may affect the safe operation of the entire system. In the performance of the SSHA, it is prudent to examine previous analyses that may have been performed such as the preliminary hazard analysis (PHA) and the failure mode and effect analysis (FMEA). Ideally, the SSHA is conducted during the design phase and/or the production phase, as shown in Chapter 3, Figure 3.4. However, as discussed in the example above, an SSHA can also be done during the operation phase, as required, to assist in the identification of hazardous conditions and the analysis of specific subsystems and/or components. In the event of an actual accident or incident investigation, the completed SSHA can be used to assist in the development of a fault tree analysis by providing data on possible contributing fault factors located at the subsystem or component level. 

Failure Modes and Effects Analysis (FMEA) examines systems, element by element (Systems Safety Society 1997,3-111). The analysis procedure requires the identification of the individual components that make up the system under examination. With the components identified, the modes in which the component failures as well as the effects that that failure has upon the system are determined. A further step to the FMEA procedure is the examination of the risk associated with the failure. The risk, also referred to as criticality, provides the investigators with a method of ranking the hazards in the system and providing a method for prioritization of hazards. 

Qualitative techniques, consisting of techniques for primarily hazard identification, such as SLRA (screening level risk analysis), checklist, what-if, what-if/checklist, HAZDP (guide-word hazard and operabiUty study), and FMEiA (failure modes and effects analysis). 

For this paper we treat hazard assessment as a combination of two interrelated concepts hazard identification, in which the possible hazardous events at the system boundary are discovered, and hazard analysis, in which the likelihood, consequences and severity of the events are determined. The hazard identification process is based on a model of the way in which parts of a system may deviate fi om their intended behaviour. Examples of such analysis include Hazard and Operability Studies (HAZOP, Kletz 1992), Fault Propagation and Transformation Calculus (Wallace 2005), Function Failure Analysis (SAE 1996) and Failure Modes and Effects Analysis (Villemeur 1992). Some analysis approaches start with possible deviations and determine likely undesired outcomes (so-called inductive approaches) while others start with a particular unwanted event and try to determine possible causes (so-called deductive approaches). The overall goal may be safety analysis, to assess the safety of a proposed system (a design, a model or an actual product) or accident analysis, to determine the likely causes of an incident that has occurred. 

PHA, What-If, Bow-Tie, and HAZOP reviews are the most common industry quahtative methods used to conduct process hazard analyses, while SVAs are typically applied for process security analyses requirements. It is quahtatively estimated that up to 80% of a company s hazard identification and process safety analyses may consist of PHA, What-If, Bow-Tie, and HAZOP reviews, with the remaining 20% from Checkhst, Fault Tree Analysis, Event Tree, Failure Mode, and Effects Analysis, etc. 

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 ... 

The FMEA was invented by NASA in the 1960s. The underlying principle is that failures of individual conponents cannot be avoided, but these conponent failures must not cause a catastrophic failure of the system. Therefore, the analysis begins by identifying the various ways that each individual conponent can fail (a failure mode). Then the effect of these failures (individually and in combination) is studied. FMEA is thus a bottom-up approach that leads to identification of critical combinations of conponent failures that can cause some catastrophic failure. The result is usually an attenpt to inprove the reliability of specific conponents or to design protective redundancy into the system. In principle, FMEA requires the prediction and consideration of all failure modes of all conponents—a very large task for a conplex system... 

The methods used to identify PIEs should be described. This may include, among other things, the use of analytical methods such as master logic diagrams, hazard and operability analysis, and failure mode and effects analysis (FMEA). Initiating events that can occur owing to human error should also be considered in the identification of PIEs. Whichever method is used, it should be demonstrated that the identification of PIEs has been performed in a systematic way and has led to the development of a comprehensive list of events. 

Failure Mode and Effect Analysis, FMEA, is a hazard identification technique in which all known fiiilure modes of conqwnents or features of a q stem are considered in turn and undesired outcomes are noted. The system has had limited use in the chemical industry in Europe as it is tedious and does not readily identify conqxrsition chan. Data for reliabilify studies can be very difficult to obtain. 

These functions are the basis for the Functional Hazard Assessment (FHA), for the identification of possible hazards. In workshops with experts - to combine technical, domain and safety know-how - various techniques are applied. This includes brainstorming, use of historical data and functional failure modes and effects analysis to identrfy possible failure modes, their operational effects and the respective severity of the worst credible outcome. Based on the safety-relevant failure modes, potential hazards are determined and respective risks are allocated according to the risk matrix. The FHA leads to derivation of top level hazards. 

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