Pressure vessel

From Free net encyclopedia

A pressure vessel is a container designed to hold gases or liquids at a pressure different from the ambient pressure.

Examples of pressure vessels are: diving cylinder, recompression chamber, distillation towers in oil refineries and petrochemical plants, nuclear reactor vessel, habitat of a space ship, habitat of a submarine, pneumatic reservoir and hydraulic reservoir.

In the industrial sector, pressure vessels are designed to operate safely at a specific pressure and temperature, technically referred to as the "Design Pressure" and "Design Temperature". A vessel that is inadequately designed to handle a high pressure constitutes a very significant safety hazard. Because of that, the design and certification of pressure vessels is governed by design codes such as the ASME Boiler and Pressure Vessel Code (BPVC) in North America, the Pressure Equipment Directive of the EU (PED), Japanese Industrial Standard (JIS), CSA B51 in Canada and other international standards.

No matter what shape it takes, the minimum mass of a pressure vessel scales with the pressure and volume it contains. For a sphere, the mass of a pressure vessel is

<math>M = {3 \over 2} P V {d \over s}</math>

Where <math>M</math> is mass, <math>P</math> is pressure, <math>V</math> is volume, <math>d</math> is the density of the pressure vessel material, and <math>s</math> is the maximum working stress that material can tolerate. Other shapes besides a sphere have constants larger than 3/2.

So, for example, a typical design for a minimum mass tank to hold helium (as a pressurant gas) on a rocket would use a spherical chamber for a minimum shape constant, carbon fiber for best possible d/s, and very cold helium for best possible mass/PV. There is no theoretical efficiency of scale to be had in a pressure vessel.it:Recipiente in pressione