Failure Modes Effects Analysis effect evaluation

Two distinctly different, yet complementary, perspectives of hazards for the HCF and associated radioactive material storage locations are obtained for the overall hazard analysis of Chapter 3 by using both PHA and failure mode effects analysis (FMEA) techniques. FMEA is a complementary type of evaluation that utilizes a system failure-based form of analysis. Unlike PHA, the first objective of FMEA is to subdivide the facility Into several different (and, to the maximum extent possible, independent) system elements. Failure modes of each system element are then postulated and a structured examination of the consequences of each failure mode follows. However, similar to PHA, FMEA documents preventive and mitigative features (failure mechanisms and compensation) and anticipated accident consequences (failure effects). Appendix 3D contains the FMEA for the HCF. 

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). 

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. 

The goal of risk analysis is to identify events that may have one or several undesirable consequences on a system, and to assess the likelihood and severity of these consequences. A lot of methods can be used to conduct risk analysis (Flaus, 2013a) such as Preliminary Hazard Analysis (PHA) and Failure Mode Effects Analysis (FMEA) (Papadopoulos et al., 2004). In most of these methods, the obtained information may be used to build a risk model. The next step after risk analysis is to study the behavior of the system, when the undesirable events occur, in order to evaluate its performance in degraded conditions, and its robustness or resilience. An approach to allow integrated risk analysis and simulation has been proposed for business process management (Tjoa et al., 2011). 

Qualification of a capillary electrophoresis instrument is performed using failure mode, effects, and criticality analysis as the risk analysis tool. The instrument is broken down into its component modules and the potential failures of those components identified. The potential effect of those failures is defined and the risk characterized. Any current evaluation of those failures is identified and any recommended actions to mitigate the risk defined. 

Failure Mode, Effects and Criticahty Analysis (FMECA) is a systematic process widely used foriden-tifying and evaluating potential failures of mechanical systems, in order to prevent them and minimize the risk associated with unexpected brake down. The traditional FMECA methodology is based on the following steps ... 

In 1985, the American Institute of Chemical Engineers (AIChE) initiated a project to produce the Guidelines for Hazard Evaluation Procedures. This document, prepared by Battelle, includes many system safety analysis tools. Even though frequently identified as hazard and operability (HazOp) programs, the methods being developed by the petrochemical industry to use preliminary hazard analyses, fault trees, failure modes, effects, and criticality analyses, as well as similar techniques to identify, analyze, and control risks systematically, look very much like system safety efforts tailored for the petrochemical industry (Goldwaite 1985). 

The remainder of this chapter will discuss HAZOP and what-if techniques in detail and illustrate specific examples of how they are applied. Chapter 7 will address fault tree analysis and Chapter 8 will discuss failure modes effects and criticality analysis. An excellent reference manual for these techniques is the Guidelines for Hazard Evaluation Procedures, published by the American Institute for Chemical Engineers CCPS (2008). 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

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. 

Failure Modes and Effects Analysis (FMEA) - A systematic, tabular method of evaluating the causes and effects of known types of component failures, expressed in an annual estimation. 

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. 

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... 

The failure mode and effect analysis (FMEA) is generally applied to a specific piece of equipment in a process or a particularly hazardous part of a larger process. Its primary purpose is to evaluate the frequency and consequences of component failures on the process and surroundings. Its major shortcoming is that it focuses only on component failure and does not consider errors in operating procedures or those committed by operators. As a result, it has limited use in the chemical process industry. 

A systems hazards analysis (SHA) is a systematic and comprehensive search for and evaluation of all significant failure modes of facility systems components that can be identified by an experienced team. The hazards assessment often includes failure modes and effects analysis, fault tree analysis, event tree analysis, and hazards and operability studies. Generally, the SHA does not include external factors (e.g., natural disasters) or an integrated assessment of systems interactions. However, the tools of SHA are valuable for examining the causes and the effects of chemical events. They provide the basis for the integrated analysis known as quantitative risk assessment. For an example SHA see the TOCDF Functional Analysis Workbook (U.S. Army, 1993-1995). 

When analysis is needed of a small portion of a large process or of an item of equipment, such as a reactor, the Failure Mode and Effect method can be used (2). While this method may not evaluate operating procedure errors or omissions, or the possibility or probability of operator error, it does assess the consequences of component failures on the process. This type of analysis has been used infrequently at the Experimental Station, and then most often in a somewhat modified form. 

Other tools Information from any of the methods for gathering information can be summarized using a tree diagram. A tree diagram is similar to a cause-and-effect diagram when causes of an event are being evaluated. Standard symbols are used with tree diagrams for applications like fault tree analysis or failure mode and effects antilysis (FMEA). 

Before we can define the mission for any particular test or inspection system we must be able to specify customer needs. While a detailed framework for designing inspection systems is given in Section 7, we must consider now how to define such needs. One way is to apply a failure modes and effects analysis (FMEA) to the product and design a test and evaluation system to cover each of the potential failure modes. But this technique does not make the customer an explicit part of the design process, whereas we have seen earlier (Section 1) that direct customer input is increasingly needed in more customized products. A preferable technique is to begin with customer function and quality requirements as the basis for a list of product attributes that form the basis of test and inspection. In attributes inspection (Section 2.1), this list is often a defect list or fault list defining the discrete defects that the inspection system must ensure the customer never experiences. 

Failure mode and effects analysis is a design-evaluation procedure used to identify all conceivable and potential failure modes and determine the effect of each failure mode on system performance. This procedure is accomplished by formal documentation, which serves (1) to standardize the procedure, (2) as a means of historical documentation, and (3) as a basis for future improvement. 

It is critical to spend early development time using failure mode and effects analysis (FMEA) and establishing a design plan that minimizes or eliminates the potential failure modes identified as part of the design FMEA. Using multiple tests to evaluate failure modes is also a key component to success. 

A consultant can provide fresh ideas as to how to perform well-understood tasks. For example, in Chapter 5, it was pointed out there is a wide variety of PHA techniques that can be used. If a company has become stuck with one method, say the Hazard and Operability technique, a consultant can help them evaluate and use other methods such as What-lf or failure mode and effects analysis. 

In several industries (automobiles, semiconductors), failure modes and effects analysis has been the technique of choice by design engineers for reliability and safety considerations. They are used to evaluate (a) the ways in which equipment fails and (b) the response of the system to those failures. Although an FMEA is typically made early in the design process, the technique can also serve well as an analysis tool throughout the life of equipment or a process. 

Since diagnostics are such a critical variable in the calculations, the ability to measure and evaluate the effectiveness of the diagnostics is important. This is done using an extended failure modes and effects analysis technique (Ref. 9) and verified with fault injection testing (Ref. 10 and 11). The techniques were refined to include multiple failure modes (Ref. 12) and today are commonly used to evaluate diagnostic capability and failure mode split (Ref. 13). 

Failure Mode and Costs Analysis. Failure Mode and Cost Analysis (Figure 2) applied to the omission of an activity in the Integrated Management System enables the systematic consideration of the failure modes that may result from the described omission and the evaluation of the probability and cost effective of this failure form. The P Index (on a scale of 1 to 10), called rate of occurrence, is assigned to the probability occurrence of the failure form. The C Index (on a scale of 1 to 10), called cost index is assigned to the effective failure cost. The product of both indices is called cost priority number (CPN). Value of CPN identifies the significant failure forms. The cost of a failure form will be the product of the failure mode probability and the effective failure cost. 

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