Pressure and Temperature Limits

GENERAL MATERIAL MAXIMUM DESIGN PRESSURE and TEMPERATURE LIMITS UMITED BY CORROSION ALLOWANCE CONSTRUCTION Carbon Steel 275 PSIG at -20/I00°F 100 PSIG at 750°F 150 Flanges See Table, This Spec. ly" and Smaller—Socket Welded 2" and Larger—Flanged and Butt-Welded... 

An ideal split-shaft Brayton cycle receives air at 14.7 psia and 70° F. The upper pressure and temperature limits of the cycle are 60 psia and 1500°F, respectively. Find the temperature and pressure of all states of the cycle. Calculate the input compressor work, the output power turbine work, heat supplied in the combustion chamber, and the thermal efficiency of the cycle, based on variable specific heats. 

As shown in Figure 7.13 the pressure and temperature limits to the hydrate stability exists from the seafloor (because hydrates are less dense than seawater) to the intersection of the geotherm (BGHS). The solubility limit, however, imposes a further depth restriction because the methane concentration must equal the solubility limit to be in equilibrium with hydrates. It is assumed that the sediment provides sufficient nucleation sites so that there is no methane metastability, so hydrate forms in the narrow depth region where methane concentration lies atop the methane solubility line. As illustrated in the Leg 311 case study, the GHOZ is always smaller than the GHSZ. 

The sudden increase in Cp with temperature at the highest pressure and high temperatures is interesting, although care should be taken in relying too heavily on this result, since it represents a prediction of the third derivative of the chemical potential near both the pressure and temperature limits of the reliability of the equations. 

The differences cannot be easily explained. The selection rules are often heavily influenced by economical considerations alone. The technological parameters are flux, recirculation rate, chemical compatibility, pore size or molecular weight cutoffs, pressure and temperature limitations, and cleane-ability. Once the feasibility has been established, the engineering design and scale-up come into play. 

Molders utilizing this system require equipment to measure and control the amount of entrained gas in the liquid at the desired level. They can include mass flow meters with density devices, nuclear density monitoring devices, as well as a variety of other densities measuring devices to control nucleation level. All these systems work within very defined pressure and temperature limits however, outside these limits, readings become erratic. There are systems that remove the dependence on system pressure and temperature. This system provides more consistent data. 

Highlight (polycarbonate) for the polymer and press ENTER. Note the pressure and temperature limits for the Tait equation. In this case, the pressure limits are 0.0 and 1.77E + 08 pascals and the temperature limits are 430 and 610 K. 

For flanges of nonstandard dimensions or for sizes beyond the scope of the approved standards, design shall be in accordance with the requirements of the ASME Boiler and Pressure Vessel Code, Sec. VIII, except that requirements for fabrication, assembly, inspection testing, and the pressure and temperature limits for materials of the Piping Code are to prevail. Countermoment flanges of flat face or otherwise providing a reaction outside the bolt circle are permitted if... 

On the basis of the pressure and temperature limits thus specified the number of hydrating agents which have any reasonable chance of becoming important can be reduced to about 12, shown in Table I. Further work has been reported on F-31, methyl bromide, and F-21 (2) and on propane (6) and this paper presents thermodynamic data on F-142b and F-12B1. Except for chlorine, similar data can probably be predicted for the remaining six agents with sufficient accuracy for economic evaluation studies (1). 

For preliminary design, column operating pressure and type condenser can be established by the procedure shown in Fig. 12.4, which is formulated to achieve, if possible, reflux drum pressures Pp between 0 and 415 psia (2.86 MPa) at a minimum temperature of 120°F (49°C) (corresponding to the use of water as the coolant in the overhead condenser). The pressure and temperature limits are representative only and depend on economic factors. Both column and condenser pressure drops of 5 psia are assumed. However, when column tray requirements are known, more refined computations should allow at least 0.1 psi/tray for atmospheric or superatmospheric column operation and 0.05 psi/tray pressure drop for vacuum column operation together with a 5 to 2 psia condenser pressure drop. Column bottom temperature must not result in bottoms decomposition or correspond to a near-critical condition. A total condenser is used for reflux drum pressures to 215 psia. A partial condenser is used from 215 psia to 365 psia. A refrigerant is used for overhead condenser coolant if pressure tends to exceed 365 psia. 

Safe Upper and Lower limits (particularly pressure and temperature limits for the equipment items)... 

In addition to the limitations mentioned on pressure and temperature, limits should be stated for chemical quality of the reactor coolant for instance, in water cooled reactors, the conductivity, the pH value, the oiqrgen content and the levels of impurities such as chlorine and fluorine are important. 

There have been numerous reported incidents of pressure transients in PWRs where Technical Specification pressure and temperature limits of the RCS have been exceeded. The majority of these events occurred while the reactor was in startup or shutdown conditions and at low reactor vessel temperatures. The issue is the reliability of the cold overpressure protection system and especially the safety and relief valves situated either on the pressurizer or RHR systems. The protection systems in US plants used to mitigate and reduce the potential for these events are termed low temperature overpressure protection (LTOP) systems. 

Pressure and temperature limits should be established for the pressure vessel and the vessel wall should be designed to withstand aU the cychc loads that are expected to occur over the plant lifetime. The design documentation should include clear specifications of those loads that are necessary for the determination of the cumulative usage factor. 

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