Pressure vessels design temperature

The objective function or the constraint functions may be defined in terms of complicated interactions of the variables. A familiar case of interaction is the temperature and pressure dependence in the design of pressure vessels. For example, if the objective function is given as / = I5.5xxx2m, the interaction between xx and x2 precludes the determination of unique values of xx and x2. Many other more complicated and subtle interactions are common in engineering systems. The interaction prevents calculation of unique values of the variables at the optimum. 

The pressure vessel design codes and standards include lists of acceptable materials, in accordance with the appropriate material standards. The ASME BPV Code Sec. II Part D gives maximum allowable stresses as a function of temperature and maximum temperatures permitted under Sections I, III, VIII, and XII of the BPV code for ferrous and nonferrous metals. The design of pressure vessels using reinforced plastics is described in ASME BPV Code Sec. X. 

Figure 1. Insulation design for pressure vessel. The figure shows a vacuum space for obtaining good performance from the multilayer insulation, instramentation for pressure, temperature and level, and a vapor shield for reducing hydrogen evaporative losses.

High-pressure operations should be carried out only with equipment specifically built for this use and only by those trained especially to use this equipment. Reactions should neva- be carried out in, nor heat applied to, an apparatus that is a closed system unless it has been designed and tested to withstand pressure. To ensure that the equipment has been properly designed, each pressure vessel should have stamped on it, or on an attached plate, its maximum allowable working pressure, the allowable temperature at this pressure, and the material of construction. Similarly, the relief pressure and setting data should be stamped on a metal tag attached to installed pressure-relief devices, and the setting mechanisms should be sealed. Relief devices used on pressure regulators do not require these seals or numbers. 

When designing the pressure vessels and associated plant it is often assumed that pressure and temperature within the vessel change linearly with time during pressure release and that the temperature is clearly defined. Figure 8.9 portrays this simplified view. 

In reality, there is a distribution of temperature over the vessel and within the walls and the pressure and temperature transients do not show linear behaviour. In German codes for the design of pressure vessels [9] it is of great importance, whether or not the wall temperature falls below - 10 C. Bearing this in mind, tests were carried out using a 50 1 vessel, initially containing... 

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. 

Storage of Flammable Materials. The preferred storage for flammable Hquids or gases is in properly designed tanks. Floating roof tanks frequently are used in the petroleum industry for flammable cmdes and products (see Tanks and pressure vessels). The vents on cone roof tanks should either be equipped with flame arrestors or the vapor space above the contents should be inerted with a nonflammable gas or vapor, unless the flash point is weU above the maximum ambient temperature, the contents are not heated above the flash point, and the tank is not exposed to other tanks containing flammable Hquids. 

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. T11, except that requirements for fabrication, assembly, inspection testing, and the pressure and temperature hmits 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... 

MAX. ALLOWABLE WORKING UG-98 TEMPERATURE. DESIGN UG-19, UG-20 PRESSURE VESSELS SUBJECT TO DIRECT FIRING UW-2(d), U-I(h)... 

Design conditions range in pressures from full vacuum to 96.5 bar g and in temperatures from —269°C to 200°C. This is accomphshed meeting the quality standards of most pressure vessel codes. 

Pressure Vessels. Refineries have many pressure vessels, e.g., hydrocracker reactors, cokers, and catalytic cracking regenerators, that operate within the creep range, i.e., above 650°F. However, the phenomenon of creep does not become an important factor until temperatures are over 800°F. Below this temperature, the design stresses are usually based on the short-time, elevated temperature, tensile test. 

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