Cause Failures

Control of quality and state of engine parts, components of electric, pneumatic, hydraulic systems, load-bearing elements Investigations of parts and units failure causes... 

Failure Cause. The failure cause is the physical, chemical, electrical, thermal, or other design deficiency which caused the failure. The agent, physical process, or hardware deficiency causing the failure mode must be identified, ie, what caused the failure for each failure mode. There may be more than one cause. Failure Fffect. The failure effect is the local effect on the immediate component/subsystem and the global effect on system performance/operation. In commercial products, the effect on the customer, ie, the global effect, must be addressed. 

Cardiomyopathy. Cardiomyopathy, or diseased heart muscle, may reach a point at which the heart can no longer function. It arises from a combination of factors, including hypertension, arrhythmias, and valve disease. Other problems, such as congestive heart failure, cause the interrelated heart—lung system to break down. Because the heart can no longer adequately pump, duid builds up in the lungs and other areas. 

A reasonably close match of thermal expansion of the coating and substrate over a wide temperature range to limit failure caused by residual stresses is desired for coatings. Because temperature gradients cause stress even in a weU-matched system, the mechanical properties, strength, and ductUity of the coating as well as the interfacial strength must be considered. 

All areas of the cooling water system where a specific form of damage is likely to be found are described. The corrosion or failure causes and mechanisms are also described. Especially important factors influencing the corrosion process are listed. Detailed descriptions of each failure mode are given, along with many common, and some not-so-common, case histories. Descriptions of closely related and similarly appearing damage mechanisms allow discrimination between failure modes and avoidance of common mistakes and misconceptions. 

The accuracy of absolute risk results depends on (1) whether all the significant contributors to risk have been analyzed, (2) the realism of the mathematical models used to predict failure characteristics and accident phenomena, and (3) the statistical uncertainty associated with the various input data. The achievable accuracy of absolute risk results is very dependent on the type of hazard being analyzed. In studies where the dominant risk contributors can be calibrated with ample historical data (e.g., the risk of an engine failure causing an airplane crash), the uncertainty can be reduced to a few percent. However, many authors of published studies and other expert practitioners have recognized that uncertainties can be greater than 1 to 2 orders of magnitude in studies whose major contributors are rare, catastrophic events. 

Ceramics, without exception, are hard, brittle solids. When designing with metals, failure by plastic collapse and by fatigue are the primary considerations. For ceramics, plastic collapse and fatigue are seldom problems it is brittle failure, caused by direct loading or by thermal stresses, that is the overriding consideration. 

Meher-Homji C.B., and Gabriles G.A., Gas Turbine Blade Failures—Causes, Avoidance, and Troubleshooting, Proceedings of the 27th Turbomachinery Symposium, Texas A M University, pp. 129, 1998. 

Woollatt, D., Increased Life for Feather Valves of Failure Caused by Impact, Proceedings of the 1980 Purdue Compressor Technology Conference, Purdue University, West Lafayette, IN, 1980, pp. 293-299. 

LOCA, is presented in Table 3.4.5-1. In preparing the event tree, reference to the reactor s design determines the effect of the failure of the various systems. Following the pipe break, the system should scram (Figure 3.4.5-2, node 1). If scram is successful, the line following the node goes up. Successful initial steam condensation (node 2 up) protects the containment from initial overpressure. Continuing success in these events traverses the upper line of the event tree to state 1 core cooled. Any failures cause a traversal of other paths in the evL-nl tree. 

After a layer fails, the behavior of the laminate depends on how the mechanical and thermal interactions between layers uncouple. Actually, failure of a layer might not mean that it can no longer carry load. In the present example of a cross-ply laminate, the inner layer with fibers at 90° to the x-axis has failed, but, because of the orientation of the fibers (perpendicular to the main failure-causing stress), the failure should be only a series of cracks parallel to the fibers. Thus, stress can still be carried by the inner layer in the fiber direction (y-direction). 

Many companies now insist that if use of the wrong grade of steel can affect the integrity of the plant, all steel must be checked for composition before use. This applies to flanges, bolts, welding rods, etc., as well as the raw pipe. Steel can be analyzed easily with a spectrographic analyzer. Other failures caused by the use of the wrong construction material are described in Section 16.1. 

Time-Related and Demand-Related Failure Causes... 

The main objective of the In-Plant Reliability Data System (IPRDS) was to develop a comprehensive and component-specific data base for PRA and other component reliability-related statistical analysis. Data base personnel visited selected plants and copied all the plant maintenance wor)c requests. They also gathered plant equipment lists and plant drawings and in some cases interviewed plant personnel for Information on component populations and duty cycles. Subsequently, the maintenance records were screened to separate out the cases of corrective maintenance applying to particular components these were reviewed to determine such things as failure modes, severity, and, if possible, failure cause. The data from these reports were encoded into a computerized data base. 

Analysis of Dependent Failure Events and Failure Events Caused by Harsh Environment Conditions Nuclear 700 events representing common cause failures and failures caused by harsh environments Licensee Event Reports on failures of 26 component and subcomponent types listed below 94. 

Investigation of Valve Failure Problems in LWR Power Plants Nuclear 195 LERs valve failures causing trips from 12/72 to 12/78. plus all valve failures for 10 stations from 2/66 to 1/79 Valve-related events reported in LERs. as noted above 105. 

This is a letter report from JBF Associates Inc., to Sandia National Laboratories (SNL) summarizing JBF s efforts to analyze dependent (common cause) failures and failures caused by harsh environments. The information used for the analysis was ta)cen from over 1000 failure reports (mostly abstracts of LERs that were assembled for other studies). The 26 groups of components selected for study are accumulators, batteries, cables, control rod drives,... 

NUMBER AND TYPE OF RECORDS 195 LERs valve failures causing trips from... 

The seven single failures causing moderate release of toxic vapor... 

Mauzy, H. L., Minimize drillstem failures caused by hydrogen sulfide, World Oil, November 1973. 

Cohen, J. and Wulff, J., Clinical Failure Caused by Corrosion of a Vitallium Plate , Journal of Bone and Joint Surgery, 54A, 617-628 (1972)... 

Let Ut(t) be the expected number of system failures caused by failures of components in the position by time t, where the initial component is new at time zero, then... 

Process contamination may, unfortunately, occur regularly in certain industries, and these process materials inevitably find their way into the FW system, and from there to the boiler, unless adequate precautions are taken. The result is severe fouling of the boiler, contamination of the steam generation process, and the potential for damage and boiler failure caused by overheating. 

Patients with complex I deficiency may also present with severe congenital lactic acidosis, hypotonia, weakness, cardiomyopathy, and cardiorespiratory failure caus-... 

O Brien KL et al. Epidemic of pediatric deaths from acute renal failure caused by diethylene glycol poisoning. Journal of the American Medical Association, 1998, 279(15) 175-78. 

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