Wall pressure

Figure 9.4 A thick-walled pressure vessel might be economical when compared with a thin-walled vessel and its relief and venting system.

Creep of Thick-walled Cylinders. The design of relatively thick-walled pressure vessels for operation at elevated temperatures where creep caimot be ignored is of interest to the oil, chemical, and power industries. In steam power plants, pressures of 35 MPa (5000 psi) and 650°C are used. Quart2 crystals are grown hydrothermaHy, using a batch process, in vessels operating at a temperature of 340—400°C and a pressure of 170 MPa (25,000 psi). In general, in the chemical industry creep is not a problem provided the wall temperature of vessels made of Ni—Cr—Mo steel is below 350°C. 

Fig. 4. Parameters in a coking cycle where (—) represents coke oven wall pressure ( ) coal charge center temperature (—) coke mass lateral contraction ...

Low-Pressure Storage Tanks Low-pressure storage tanks are fragile. Even an eggshell can withstand more pressure and vacuum (Sanders, Don t Be Another Victim of Vacuum, Chemical E/ig. Prog., September 1993, pp. 54-57). Low-pressure storage tanks do not require much pressure difference between the inside of the tank and the atmosphere to buckle the relatively thin tank walls. Pressure... 

Figure B-2. Psychrometric chart atmospheric air, mixture pressure (barometric) 29.921 in. Hg. (From Short, Kent and Walls, Pressure-Enthalpy Otarts for Selected Engineering Substances. Gulf Publishing Company, Houston, TX, 1970.)...

A thin-walled pressure vessel is one in which the wall thickness t is small when compared to the local radius of curvature r. At a point in the wall of the vessel where the radius of curvature varies with the direction, the wall stresses are... 

Thermal boundary condition at constant wall pressure Wall, water... 

In all the major industrialised countries the design and fabrication of thin-walled pressure vessels is covered by national standards and codes of practice. In most countries the standards and codes are legally enforceable. 

The maximum shear stress will depend on the sign of the principal stresses as well as their magnitude, and in a two-dimensional stress system, such as that in the wall of a thin-walled pressure vessel, the maximum value of the shear stress may be that given by putting (73 = 0 in equations 13.3 and c. 

Jasper, McL, T. and Scudder, C. M. (1941) Trans. Am. Inst. Chem. Eng. 37, 885. Multi-layer constmction of thick wall pressure vessels. 

Mineral Oil Hydraulic Fluids. No specific methods were located for interfering with the mechanism of action for toxic effects produced by mineral oil hydraulic fluids. Unstable alveoli and distal airways have been proposed as major factors in the respiratory symptoms that occur after the ingestion of other petroleum-derived materials. Continuous positive airway pressure or continuous negative chest wall pressure, as well as the application of supplemental oxygen, have been recommended to counteract the resultant pneumonitis (Eade et al. 1974 Klein and Simon 1986). 

According to Kinetic-Molecular Theory, the pressure exerted by a gas upon the walls of its container is caused by gas molecules hitting the walls. Pressure depends on... 

The results of calculation of AP are presented in Fig. 23.5. It can be seen from AP along the length of the combustor, the elliptic nozzles provide better combustion performance than round nozzles. A better indicator of enhancement of supersonic mixing and combustion is obtained from the analysis of the impact of the fuel supply mode on the characteristic pressure-area integral for the diverging-area supersonic combustor [6, 7]. The combustion-induced pressure-area integrals for the 2D combustor (Fig. 23.1a) were calculated from the measured axial wall pressure distributions from the following relationship [7]... 

For reactions in which only a slight pressure rise is expected (e.g., emulsion polymerization of gaseous monomers), thick-walled pressure bottles which are carefully placed behind a protective shield, can be used. For higher pressures or large-scale experiments, autoclaves are always to be preferred. 

Compaction profiles, which are plots of radial (die wall) pressure vs. axial (compaction) pressure to determine compression and decompression behavior... 

The bodies of thick-walled pressure-vessels with an outer- to inner-diameter ratio d /dj > 1.2 can either be manufacured as monobloc (solid-wall vessels) or be constructed of several layers (multi-wall vessels). During the process of design and fabrication of such vessels some significant and common rules must be observed ... 

B. Mi, P.W. Wypych, Investigations into wall pressure during slug flow conveying, Powder Technol. 84 (1995) 91-98. 

Figure 8.6. Janssen s model for stress distribution in cylindrical bins (a) Schematic of the forces applied to a differential slice (b) Wall pressure distribution Eq. (8.16).

It should be noted that the main objective in all of the foregoing analyses is to estimate the upper bounds of wall pressure distributions in bins and hoppers for both active and passive stresses. Simplicity of calculations in these methods makes them appropriate for structural design purposes of bins and hoppers. However, they are not meant to introduce a complete solution for the stress field within the bulk solids. 

Bean, H. S., Beitler, S. R., and Sprenkle, R. E., Discharge Coefficients of Long-Range Nozzles When Used with Pipe-Wall Pressure Taps, Trans. ASME 63 439, 1941. 

An intermediate form of isostatic pressure sintering, sometimes referred to as pseudo-isostatic hot-pressing, uses uniaxial hot-pressing apparatus but immerses the object to be sintered in a refractory non-interacting powder within the die and punches. This avoids the very considerable expense of building a furnace inside a thick-walled pressure vessel but the results are inferior to those achieved with true isostatic hot-pressing. 

It is therefore evident that only when the gas rate is less than the design value can stability of operation be insured. However, under this subcritical operation, excessive wall pressure, and therefore pressure drop, would be incurred. 

Finally, as the lower punch rises and pushes the tablet upward, there is a continued residual die wall pressure and considerable energy may be expanded due to the die wall friction. As the tablet is removed form the die, the lateral pressure is relieved, and the tablet undergoes elastic recovery with an increase in the volume of the portion removed from the die. 

A widely accepted theory for lamination presented by Long [29] and reformulated by Ritter and Sucker [30] attributes capping to the residual die wall pressure. This pressure is said to cause internal shear stresses in the tablet causing the propagation of cracks, which results in lamination or capping. The propagation of cracks can be prevented by plastic relaxation of shear stresses. Therefore, materials having sufficient plasticity may not be susceptible to lamination. Some properties of the powder mixture, such as moisture content, type and amount of the binder, and... 

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