Component failure analysis

Component failure analysis (CFA) It looks at the piece of the machine that failed, such as a bearing or a gear to determine the specific cause of the failure (fatigue, overload, or corrosion) and that there were these x, y, and z influences. 

Jansen, J., Plastic Component Failure Analysis, Adv. Mater. Processes (May 2001), p. 58. 

This data would be utilized after calculating the critical penetration thickness for a candidate protection system and the critical mass oif a micrometeoroid that would cause penetration of the candidate protection system, Sections 10.4.2.2.1 and 10.4.2.2.2 respectively. The flux data could then be applied to the probability of component failure analysis, described in Section 10.4.2.2.3. Once the probability is calculated, an evaluation would take place to assess whether the calculated probability is within acceptable mission parameters. Iterations in the design of the protection system would occur until an acceptable probability of failure is reached. 

A reliability block diagram can be developed for the system from the definition of adequate performance. The block diagram represents the effect of subsystem or component failure on system performance. In this preliminary analysis, each subsystem is assumed to be either a success or failure. A rehabihty value is assigned to each subsystem where the appHcation and a specified time period are given. The reUabiUty values for each subsystem and the functional block diagram are the basis for the analysis. 

In some instances, plant-specific information relating to frequencies of subevents (e.g., a release from a relief device) can be compared against results derived from the quantitative fault tree analysis, starting with basic component failure rate data. 

This analysis underscores the importance of examining failed components before they are cleaned or in any way altered. It also demonstrates the potential complexity of failure analysis and the need that exists to discard explanations that do not adequately account for all relevant observations. Important also to note is the potential connectedness of environmental factors, such that the seasonal development of seed hairs in a field of grass near a cooling tower would eventually contribute to perforations of tubes in a condenser. 

The second misconception involves the perception of what constitutes a defect. A defect is not simply a visually observable discontinuity such as a hole, lap, or seam in a component. Defects, from a failure-analysis standpoint, may also be such things as a high residual stress that may lead to cracking or unfavorable microstructures that can lead to either... 

We previously encountered failure modes and effects (FMEA) and failure modes effects and criticality analysis (FMECA) as qualitative methods for accident analysis. These tabular methods for reliability analysis may be made quantitative by associating failure rates with the parts in a systems model to estimate the system reliability. FMEA/FMECA may be applied in design or operational phases (ANSI/IEEE Std 352-1975, MIL-STD-1543 and MIL-STD-1629A). Typical headings in the F.Mld. A identify the system and component under analysis, failure modes, the ef fect i>f failure, an estimale of how critical apart is, the estimated probability of the failure, mitigaturs and IHissihiy die support systems. The style and contents of a FMEA are flexible and depend upon the. ilitcLiives of the analyst. 

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. 

Loc.ttion and the elevation are important in flooding analysis. Codes such as COMCAN HI or SETS for dependent failure analysis listed in Table 3.6-4 may be used for locating components that would be affected by flooding. These codes. serve this purpose with a complex component identifier for location and elevation. 

The FMEA approach is a bottom-up approach, looking at component failures and establishing their effect on the system. An alternative approach is to use a top-down approach such as Fault Tree Analysis to postulate system failure modes and establish which processes, procedures, or activities are likely to cause such failures. 

Analysis of accidents and major losses in the CPI indicates that they rarely arise from a single human error or component failure. Often there is a combination of some triggering event (hardware or human) together with preexisting conditions such as design errors, maintenance failures or hardware deficiencies. 

The objective of this notebook was the collection, analysis, and presentation of nonelectronic component failure data and the presentation of analytical methods that form the state-of-the-art in nonelectronic reliability analysis. This report replaces the former Nonelectronic Reliability Notebook (RADC-TR-75-22). 

This report evaluates recent performance of DGs and all DG vendors with the exception of Transamerica Delaval, Inc. (TDl), because of the emphasis already being given to TDI diesels in other studies. For the period 1980 through 1983 inclusive, BNL reviewed and evaluated DG failure data, DG vendor inspection reports, the TDI lessons learned as they related to the other vendors, and previous pertinent studies. The data sources used for DG failure analysis were LERs, 10 CFR 50.55E, Part 21, NPRDS, and EPRI document files. The DG failures were classified relative to the DG component that failed (e.g., main bearings, starting system). The failures were also categorized and analyzed by mode, manufacturer, and cause. Manufacturers with significant failures are identified in the report. 

Opening segments of the IP2 PRA data analysis section describe the definitions of terms and concepts employed, the assumptions made, and limitations recognized during the data base construction. A set of 39 plant-specific component failure mode summaries established the basis for component service hour determinations, the number of failures, and the test data source for each failure mode given for each component. Generic data from WASH-1400, IEEE Std 500, and the LER data summaries on valves, pumps, and diesels were combined with plant-specific failure data to produce "updated" failure information. All the IP2 specialized component hardware failure data, both generic and updated, are contained in Table 1.5.1-4 (IP3 1.6.1-4). This table contains (by system, component, and failure mode) plant-specific data on the number of failures and service hours or demands. For some components, it was determined that specifications of the system was warranted because of its impact on the data values. 

In addition to identifying general failure modes that are common to many types of machine-train components, failure-mode analysis can be used to identify failure modes for specific components in a machine-train. However, care must be exercised when analyzing vibration profiles, because the data may reflect induced... 

Oil-related analysis encompasses a variety of physical and chemical tests such as viscosity, total acid number and particulate contamination. This is often extended to include the identification of wear debris, as an early warning of component failure, by either spectrographic... 

Failure analysis statistics have consistently shown that many machinery components failures can be directly attributed the equipment being operated outside of design parameters or unintended conditions. Most failure analysis and trouble-shooting activities are usually post-mortem and commence after installation and start-up of the equipment. The maintenance phase is now in motion, and failure analysis and trouble-shooting is now an integral part of that phase. 

Usually most machinery failure analysis is performed at component level, therefore, a definition is required to state what constitutes life attainment in connection with component failure. Defect limit is a term that is used in this context and needs to be expanded upon to understand it fully. 

The third step is to proceed to the component level because more than likely, the cause will be uncovered here. Table 62.2 shows machinery component failure modes commonly encountered in machinery failure analysis together with suggested standard life values, Weibull indices (/J), and responsiveness to preventable or predictable maintenance strategies. Referring to this table will help decision-making. To assist the analyst in documenting bad actor failure modes on the component level. 

Contamination can be present not only as a surface deposit or a surface feature but can also be located within the bulk of a manufactured part. The selection of an appropriate series of analytical techniques, applied to failure, defect, and contamination analysis projects, is influenced by the location of the contamination or defect and the optical properties of the manufactured component. Microscopic analysis of opaque parts is limited to surface analysis... 

After repair, the component is returned to the working state. Minimal cut set analysis is a mathematical technique for developing and providing probability estimates for the combinations of basic component failures and/or human error probabilities, which are necessary and sufficient to result in the occurrence of the top event. 

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. 

Firewater Reliability - A mathematical model of the ability of the firewater system to provide firewater upon demand as required by the design of the system without a component failure, e.g., a Mean Time Between Failure (MTBF) analysis. 

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