Pressure vessels ASME codes

Pressure Vessels and Piping. Some of the most critical components of a chemical plant involve pressure vessels. A thorough knowledge of the American Society of Mechanical Engineers (ASME) Pressure Vessel Code (75) is essential for design and maintenance of chemical plants. Some states have their own codes, which usually conform closely to the ASME version (see High pressure technology Tanks and pressure vessels). 

As the size or the pressure goes up, curvature on all surfaces becomes necessary. Tariks in this category, up to and including a pressure of 103.4 kPa (15 Ibf/in"), can be built according to API Standard 620. Shapes used are spheres, ellipsoids, toroidal structures, and circular cylinders with torispherical, elhpsoidal, or hemispherical heads. The ASME Pressure Vessel Code (Sec. TII of the ASME Boiler and Pressure Vessel Code), although not required below 103.4 kPa (15 Ibf/in"), is also useful for designing such tanks. 

Tanks that could be subjected to vacuum should be provided with vacuum-breaking valves or be designed for vacuum (external pressure). The ASME Pressure Vessel Code contains design procedures. 

The standard dished head does not comply with the ASME Pressure Vessel Code. 

Petroleum pipe hues before 1969 were built to ASA (now ANSI) Standard B31.4 for liquids and Standard B31.8 for gas. These standards were seldom mandatoiy because few states adopted them. The U.S. Department of Transportation (DOT), which now has responsi-bihty for pipe-line regulation, issued Title 49, Part 192—Transportation of Natural Gas and Other Gas by Pipeline Minimum Safety Standards, and Part 195—Transportation of Liquids by Pipehne. These contain considerable material from B31.4 and B31.8. They allow generally higher stresses than the ASME Pressure Vessel Code would allow for steels of comparable strength. The enforcement of their regulations is presently left to the states and is therefore somewhat uncertain. 

A difference between tank cars and most pressure vessels is that tank cars are designed in terms of the theoretical ultimate or bursting strength of the tank. The test pressure is usually 40 percent of the bursting pressure (sometimes less). The safety valves are set at 75 percent of the test pressure. Thus, the maximum operating pressure is usually 30 percent of the bursting pressure. This gives a nominal factor of safety of 3.3, compared with 4.0 for Division 1 of the ASME Pressure Vessel Code. 

Truck cargo tanks (for dangerous materials) are built under Part 173 and Siibpart J of Part 178, DOT regulations. This includes Specifications MC-306, MC-307, MC-312, and MC-331. MC-331 is required for compressed gas. Siibpart J requires tanks for pressures aoove 345 kPa (50 Ibf/in ) in one case and 103 kPa (15 Ibf/in ) in another to be built according to the ASME Pressure Vessel Code. A particular issue of the code is specified. 

For the EPR design, the ASME pressure vessel code requires design to be done at two-thirds of the alloy s yield strength (see Fig. 

ASME Power Test Code, 417 ASME Pressure Vessel Code, 315, 316 ASME, standard atmospheric conditions, 21 Aspect ratio, 227 Atlas Copco, 96 Automatic control systems, 356, 357... 

Selected Portions of ASME Pressure Vessel Code, quoted by permission [I]... 

Air reservoirs are classified as pressure vessels and have to conform to the ASME Pressure Vessel Codes. As such, the following attachments must be fitted ... 

Reprinted with ASME permission. ASME Pressure Vessel Code, Section VIII, Division I, UG-127, 1989 Edition, pp. 86-88. 

The ASME Pressure Vessel Code [1] and the API codes or recommended procedures [10, 13, 33] recognize and set regulations and procedures for capacity design, manufacture and installation of rupture disks, once the user has established the basis of capacity requirements. 

LNG tanks are made from stainless steel or aluminum according to ASME pressure vessel codes. Since LNG is a very clean fuel (no water, very litde foreign matter, and no sulfur-based odorant), there are no problems with materials compatibility. The primary concern for LNG tanks is the thermal cycling they must endure from ambient temperature to -162°C (-260°F). 

Propane storage tanks must be built to either U.S. Department of Transportation (DOT) regulations for cylinders or American Society of Mechanical Engineering (ASME) pressure vessel codes. Steel is the most common material for propane tanks, though aluminum is also allowed and is popular for portable propane tanks. 

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