Failure Mode Effect Analysis FMEA

FMEA is a method of determining problem areas in either a process or a product by developing a list of potential failure modes, ranked according to their effect on the customer, end user or the next in line in the manufacturing process and establishing a priority system for corrective action considerations. 

Each stage in a process, or part of a product, is graded on a scale of 1 to 9 in three categories (Table 18.8)  

S = severity of failure an assessment of the seriousness of the effect O = the likelihood of the occurrence of a failure D = probability of detection of any failure 

The Risk Priority Number (RPN) is the product of the Severity (S), Occurrence (O), and Detection (D)  

Brassard M, Ritter D, The Memory Jogger II, Goal/QPC, Methuen, Ma, 1994. 

A Failure Mode Effect Analysis can be described as a systematic group of activities intended to 

Recogiuse and evaluate the potential failures of a product or process and the effects of that failme. 

Identify actions, which could eliminate or reduee the chance of the potential failure occurring. 

Define scope, functional requirements, design parameters and proeess steps. Identify potential failure modes Failure modes indicate the loss of at least one functional requirement. It is the manner in which a failure oecuis. This step in the process takes into aeeount a foresight view (based on past experience and arty new information) of what could cause a failure to the system or process. 

Potential failure effeet This step investigates the effect the failure will have on other entities or proeesses. 

One of the procedures used to determine which sensors are needed to sense process conditions and protect the process is called a Failure Mode Effect Analysis—FMEA. Every device in the process is checked for its various modes of failure. A search is then made to assure that there is a redundancy that keeps an identified source or condition from developing for each potential failure mode. The degree of required redundancy depends on the severity of the source as previously described. Table 14-2 lists failure modes for various devices commonly used in production facilities. 

In applying FMEA, a mechanical flow diagram must first be developed.. As an example, consider the check valve on a liquid dump line. It can fail 

ITCLL Fail to Control Low Level MOR Manual Override 

In order to perform a complete, formal FMEA of a production facility, each failure mode of each device must be evaluated. A percentage failure rate and cost of failure for each mode for each device must be calculated. If the ri.sk discounted cost of failure is calculated to be acceptable, then there arc the proper numbers of redundancies. If that cost is not acceptable, then other redundancies must be added until an acceptable cost is attained. 

It is obvious that such an approach would be lengthy and would require many pages of documentation that would be difficult to check. It is also obvious that such an approach is still subjective in that the evaluator must make decisions as to the consequences of each failure, the expected failure rate, and the acceptable level of risk for the supposed failure. 

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Failure Mode Effects Analysis (FMEA) A technique used to define, identify, and reduce known or potential failures to an acceptable level. [Defined for this book.]... 

In this chapter we explore the Failure Modes Effects Analysis (FMEA) and the Failure Modes Effects Criticality Analysis (FMECA) which, as the name suggests, simply is an extension of the FMEA.i This chapter will use the acronym EMEA and highlight those instances where is extended to include EMECA. 

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. 

The basic tools for quality management are discussed in Chapter 5. Some additional tools such as Quality Function Deployment (QFD) and Failure Mode Effect Analysis (FMEA) are discussed in this chapter. In addition, quality management systems such as ISO 9000, QS 9000, and systems based on the Malcolm Baldrige National Quality Award (MBNQA) are explained in the first part of the chapter. In the second part of the chapter, techniques to improve quality throughout the entire supply chain are discussed. 

One important difference between ISO 9000 and QS 9000 is that QS 9000 is not a voluntary standard. The auto companies require that all of their Tier 1 suppliers be certified to QS 9000. QS 9000 is more extensive than ISQ 9000. It requires additional quality system elements and it includes advanced quality planning. In addition, it requires that control and quality plans be developed. For example, QS 9000 requires the development of Failure Mode Effect Analysis (FMEA). The similarities and differences between ISO-9000 and QS 9000 are shown below in Table 13.3. 

Use of analytical methods such as hazard and operabiUty analysis (HAZOP), failure mode, effect analysis (FMEA) , and master logic diagrams ... 

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). 

Many tools for risk analysis are in use. ICH Q9 Briefing Packs [2] describes many of them. The best-known method might be the Failure Mode Effect Analysis (FMEA). EMEA is basically done in the following way ... 

Several methods are available for identifying and assessing hazards (Kletz, 1990). Hazards can be identified through checklists, failure mode effect analysis (FMEA), fault tree analysis, event tree analysis, what-if analysis, and hazard and operability studies (HAZOP). Assessing hazards can be done through hazard analysis (HAZAN), codes of practice, the Dow Explosion Index, and prototype index of inherent safety (PIIS). 

An assessment has been completed documenting the device random hardware failure rates using Failure Mode Effect Analysis (FMEA). The results are documented and available to owners/operators in the following format ... 

Figure A4.1 shows an extract from a failure mode effect analysis (FMEA) covering a single failure mode (e.g., OUTPUT FAILS LOW).

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). 

A failure analysis, possibly using the Failure Modes Effects Analysis (FMEA) method, is carried out for each component. 

There are various tools for risk prediction, ranging from complex mathematical models to a less complicated Event Tree Analysis. The following section provides a description of two types of risk prediction tools Data Mining and Failure Mode Effect Analysis (FMEA) ... 

Price C.J., Pugh D.R., Wilson M.S. and Snooke N., (1995) The Flame System Automating Electrical Failure Mode Effects Analysis (FMEA) , Proceedings Annual Reliability and Maintainability Symposium, pp. 90-95. 

One hazards analysis technique used to analyze equipment items is Failure Modes Effects Analysis (FMEA). The method examines the ways in which an equipment item can fiul (its failure modes), and examines the effects or consequences of such failures. If the criticaUty of each failure is to be considered, then the method becomes a Failure Modes, Effects and Criticality (FMECA) Analysis. The consequences can be linked to safety, reUability, or environmental performance. 

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