Relevant failure modes

Bearing capacity is often a requirement in specifications for hydraulic fills. This is normally related to apphed load or bearing pressure from equipment to work on the fill, shallow foundations or the future loads to be carried by the reclamation. However, when a fill layer of limited thickness is to be placed over soft subsoil, a verification of other possible failure mechanisms, such as punch through and squeezing should be carried out as well. Furthermore, slope stability is one of the main issues in land reclamation projects. Sufficient safety against loss of stability should be guaranteed during the execution (temporary boundary slopes and 

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Lubricant condition monitoring is best accomplished by the analysis of numerical data that are associated with the various fluid failure modes [2]. Numerical data can be analysed by statistical methods to determine the relationship between the various test parameters and their respective fluid and machinery failure modes. In addition, the statistical analysis can be used to determine potential data interference sources, the various alarm limits for each parameter and other criteria to be used in the daily evaluation of used oil. Note that it is important to determine all of the causes for variability in parametric data, just as it is necessary to separate changes due to interfering causes from changes with its associated relevant failure modes. 

Build the model using the checklist from above to ensure that all components and all relevant failure modes are included in the model. 

Final element components will fail also, and again the specific failure modes of the components can be classified into relevant failure modes depending on the application. It is important to know whether a valve will open or close on trip. Table 6-3 shows an example failure mode classification based on a close to trip configuration. 

Failure data for the relevant failure modes of the block valves, check valves and relief valves exist in data handbooks. The available statistics are assumed to be the mean (equal to the value reported in Table 1, taken from Wu (2007)) and the standard deviation (arbitrarily assumed equal to four times the value of Table 1). 

The system failure analysis should address all the relevant failure modes of individual items of safety system equipment. These failure modes would normally have been identified by the failure modes and effects analysis carried out as part of the design assessment. Any failures consequential to the PIE should also be included in the system model (if not already fully accounted for in the event sequence models). 

In specifying the equipment failure rates, the boundaries of the equipment should be specified and all the relevant failure modes should be included. For a pump, this includes failure to start, failure to run for the specified mission time and leakage from the pump seals. 

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. 

Third, although SAM is intended to be very much a "user aid" rather than a fully automatic tool, it must support some means of checking consistency of arguments, and between arguments and models to improve the quality of safety cases. Thus, for example, it should be possible to check that all relevant failure modes have been included in a failure modes and effects analysis, by checking the consistency of the arguments and the model. 

Over the past 8 years, a few reports of rim fracture of remelted crosslinked liners have surfaced in the literature [174, 175], as well as in FDA Maude reports (see http // www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/ search.CFM). These case reports are usually associated with thin liners associated with acetabular shells implanted with a high abduction angle. Due to the small numbers reported thus far in the literature, the incidence of rim fracture necessitating revision of crosslinked polyethylenes remains poorly understood. None of the numerous clinical studies of remelted polyethylenes have reported rim fracture as a clinically relevant failure mode. However, the few rare cases of rim fracture have provided motivation for improving the mechanical behavior of crosslinked polyethylenes, especially for thin liners. 

Explosibility and Fire Control. As in the case of many other reactive chemicals, the fire and explosion hazards of ethylene oxide are system-dependent. Each system should be evaluated for its particular hazards including start-up, shut-down, and failure modes. Storage of more than a threshold quantity of 5000 lb (- 2300 kg) of the material makes ethylene oxide subject to the provisions of OSHA 29 CER 1910 for "Highly Hazardous Chemicals." Table 15 summarizes relevant fire and explosion data for ethylene oxide, which are at standard temperature and pressure (STP) conditions except where otherwise noted. 

The power train (Figure 8-10) was eommissioned in May 1989. Table 8-1 provides data on the maehine in question. Tables 8-2 and 8-3 show flue gas analysis from the regenerator to the gas expander turbine inlet and the relevant metallurgy, respeetively. There are many possible failure modes in gas expanders, whieh inelude erosion, eatalyst deposition, and exeessive meehanieal vibration. Obviously, these faetors may also eause power loss, and some power trains do indeed fall short of produeing the expeeted power. Nevertheless, in some eases operation at off-design expander system eonditions eould be the primary eause of performanee defieieneies. 

A uniform definition of a failure and a method of classifying failures is essential if data from different sources are to be compared. The anatomy of a failure includes the initiating or root cause of a failure that is propagated by contributory causes and results in a failure mode—the effect by which a failure occurs or is observed. Modes include failure to operate, no output, failure to alarm on demand. The end result of a failure sequence is the failure effect, such as no fluid is pumped to the absorber, or a tank overflows. As discussed in Appendix A of IEEE Std. 500-1984, only the equipment failure mode is relevant for data that are needed in a CPQRA. The failure model used in this book is based upon those in the IEEE publication and IPRDS. ... 

Here we have conducted experiments to develop an understanding of how the commercial size interacts with the matrix in the glass fiber-matrix interphase. Careful characterization of the mechanical response of the fiber-matrix interphase (interfacial shear strength and failure mode) with measurements of the relevant materials properties (tensile modulus, tensile strength, Poisson s ratio, and toughness) of size/matrix compositions typical of expected interphases has been used to develop a materials perspective of the fiber-sizing-matrix interphase which can be used to explain composite mechanical behavior and which can aid in the formulation of new sizing systems. 

In general, all fluid measurement technologies must utilize effective analysis methods, performed at appropriate intervals whether sampled or online. However, what is effective There are many different equipment-monitoring techniques and most can be justified on the basis of one technical reason or another. It is not always clear which technique is the most effective or economical. Nor do all the available techniques provide reliable or early indications of relevant critical failure modes. To be effective, the monitoring instruments or sensors must indicate the critical failure modes. Finally, the cost of using a particular technique must be considered. If the relevant critical failure mode symptoms are not properly measured and trended, the (lower) cost of the instrument or method becomes questionable. 

To apply control to a process, one measures the controlled variable and compares it to the setpoint and, based on this comparison, typically uses the actuator to make adjustments to the flow rate of the manipulated variable. The industrial practice of process control is highly dependent upon the performance of the actuator system (final control element) and the sensor system as well as the controller. If either the final control element or the sensor is not performing satisfactorily, it can drastically affect control performance regardless of controller action. Each of these systems (i.e., the actuator, sensor, and controller) is made up of several separate components therefore, the improper design or application of these components, or an electrical or mechanical failure of one of them, can seriously affect the resulting performance of the entire control loop. The present description of these devices focuses on their control-relevant aspects. Later, troubleshooting approaches and control loop component failure modes are discussed. 

Finding 4-6. Each detonation-type technology has different characteristics such as destruction rate, initial capital and operating costs, and ability to be moved from one location to another that are relevant to the selection of a system for a particular project. Structural integrity, defined as a specified allowable number of detonation cycles, is another factor to be considered, as would be the results of any failure modes and effects analyses. 

Phase II focuses upon process development to result in a pilot production line capable of producing 300 bipolar plates per hour. Our goal is a complete functional pilot line, including all relevant quality assurance, failure mode and effects analysis, and statistical manufacturing characterization processes. This will be completed by transferring the most promising mass-production technique to laiger-scale and continuous equipment operation in a dedicated production line. 

INCIDENT CAUSES. Incident causes or initiating events should be readily identifiable in any PrHA method. Reviewers should use their experience to assure that all initiating events, including hardware failure modes, operator errors, administrative errors, and loss of utilities, are considered. If the process is in a location subject to external events, the PrHA should include relevant events such as earthquakes, traffic, weather, or accidents at an adjacent process. 

Identify any failures and gather the following information date of failure, time or cycles to failure, method of failure discovery, failure mode, failure cause, failed parts, relevant system (unusual loading, power, or signal) conditions, and enviromnental conditions [13]. 

A reliability engineer s first design priority is successful operation. Great effort must be made to ensure that things work. This priority is certainly logical for most systems as failure mode is not relevant. 

Table 9.13 Failure mode and effect analysis for the storage tank of Fig. 9.6 (failure of LSHL not opening on low level is not contemplated because it is not safety-relevant)...

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