Reliability requirements

Up-to-day reliability requirements as applied to NPP strength maintenance govern development of new generation of computerized systems for in-service inspection. These systems in parallel with capabilities of ordinary ultrasonic techniques allow to reconstruct high resolution image of inner flaw and increase available amount of information. 

Despite being simple, rugged, reliable, requiring low maintenance, low cost, and vibration free, steam-jet systems are not widely accepted in water chilling for air-conditioning due to characteristics of the cycle,... 

With the Industrial Revolution, life became more complex but it was not until World War II that reliability engineering was needed to keep the complex airplanes, tanks, vehicles and ships operating. Of particular concern was the reliability of radar. Prior to this time equipment was known qualitatively to be reliable or unreliable. To quantify reliability requires collecting statistics on part failures in order to calculate the mean time to failure and the mean time to repair. Since then, NASA and the military has included reliability specifications in procurements thereby sustaining the collection and evaluation of data build statistical accuracy although it adds to the cost. 

Study the reliability requirements of the process with the customer,... 

Find out the customer reliability requirements of the process. Define and obtain the customer s acceptance of the needs for ventilation system reliability (e.g., what is the allowed break-off rime). 

In electric power systems, it is essential to have permanent control of the power in electricity production, transportation, and consumption. Because of speed and reliability requirements, electric power systems were the first large systems to use a variety of automatic control devices for the protection of different parts of the system. 

Turbines can be controlled in a number of ways, depending upon the sensitivity and reliability required. 

In Table 4-2, we have the standard SMD component sizes. Note that usually, most pick and place machines cannot mount anything bigger than size 1515. So larger components may need to be hand-soldered. For ceramic capacitors, reliability requirements call for a certain... 

A set of replicate results should number at least twenty-five if it is to be a truly representative statistical sample. The analyst will rarely consider it economic to make this number of determinations and therefore will need statistical methods to enable him to base his assessment on fewer data, or data that have been accumulated from the analysis of similar samples. Any analytical problem should be examined at the outset with respect to the precision, accuracy and reliability required of the results. Analysis of the results obtained will then be conveniently resolved into two stages - an examination of the reliability of the results themselves and an assessment of the meaning of the results. 

Define reliability requirements necessary to achieve desired... 

The sizing of piping is based upon a hydraulic analysis for the water distribution network for the WCCE. The main delivery pipe should be sized to provide 150% of the design flow rate. A residual pressure and flow requirement at the most remote hydrocarbon process or storage location from the supply source dictates the sizing for the remaining system. Normal reliability requirements usually suggest that minimum of two sources of supply be available that are in themselves remote from each other. Therefore two remote flow calculations must be performed to determine the minimum pipe distribution size. NFPA 24 requires that the minimum residual pressure available in a fire main not be less than 6.9 bars (100 psi.). Velocity calculations should be performed which verify flows are not more than the limits of the material that is employed. 

The high level of safety and reliability required of nuclear power stations has meant that systematic estimates of polymer lifetime have been performed more widely here than in any other industry. The approach is described in Section 5.3. Many applications of polymers are in locations that cannot be monitored by regular inspection. The practice has been to subject polymers in these regions to independent assessment or environmental qualification , a process in which their potential degradation mechanisms are identified within a worst case environment of 40 °C and high humidity. If the predicted lifetime of a component is less than the design life of 40 years a schedule is laid down for its replacement. 

The requirement for 38 percent online availability means an offline allowance of 62 percent of the time, which can be used for equipment maintenance and repairs. The required capacity factor of 38 percent sets a very low reliability requirement for the equipment and provides a margin for combined equipment failure rates within a processing line. 

While it is easy to measure the duration of an exposure, it is not as easy to measure the concentration of an agent. There are various devices available for this purpose. Some can be used with little or no training, while others require the skills and services of a trained industrial hygienist or industrial hygiene technician. The greater the accuracy and reliability required, the greater the need for sophisticated instrumentation and the skill to use it. Some of the common devices are ... 

The physical form of the thermocouples varies significandy according to applications. Most spacecraft power supplies utilize separate thermocouples that can be checked for performance at successive stages of manufacturing and be replaced if necessary. This approach fits in very well with the extremely high reliability requirements imposed on such systems. In terrestrial systems where such individualized attention is not economically feasible, modular assemblies are generally used, which can contain tens to hundreds of couples in a single unit. 

Statistically designed studies should be performed to determine accuracy, precision, and selectivity of (lie methodology used for trace or ultratrace analyses. The reliability requirements for these studies are that the data generated withstand interlaboratory comparisons. 

It is obvious that the determined critical sampling distance depends on the statistical reliability required. A smaller confidence level (according to a higher probability of an error of the first kind) corresponds to a higher value for the critical sampling distance required. For the discussed case a change in the probability for an error of the first kind from a = 0.05 to a = 0.1 increases the critical sampling distance for lead from lcm tow = 74.3 m to lcrit iow = 78.0 m. 

Safety shutdown valves, which are normally wide open and operate infrequently, are expected to respond to a safety trip command reliably and without fault. To achieve the level of reliability required in this application, the safety valve must be periodically tested to ensure positive operation under safety trip conditions. To test the operation of the shutdown system without disturbing the process, the traditional method is to physically lock the valve stem in the wide-open position and then to electrically operate the pneumatic shutdown solenoid valve. Observing that the pneumatic solenoid valve has properly vented the actuator pressure to zero, the actuator is seen as capable of applying sufficient spring force to close the valve, and a positive safety valve test is indicated. The... 

Reliability requires the ability to consistently read a given measurement device and also requires a given measurement device to perform equally well, test after test. It is the user s responsibility to know how to achieve repeatable data from the equipment being used. 

Today s programmable microprocessor controller operating systems are the result of about a half-century of evolution and provide the available repeatability and reliability required on the plant floor. In the past, achieving these objectives meant choosing a vendor-specific operating system and choosing that vendor s entire control system. This can be a... 

Because of the very stringent reliability requirements for diagnostic applications, the only homogeneous techniques that have survived in this field are the fluorescence polarization (FP) methods originally developed by AbbotE and the homogeneous time resolved fluorescence (HTRF) and TRACE approaches developed later by CIS bio international. 

The critical field instrumentation must support accuracy and reliability requirements over the entire process range conditions. 

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