Pressure Vessels

Pressure Vessel: is a closed contained designed to hold gases or liquids at a pressure different from the ambient pressure. 

Pressure vessles are used in a variety of applications.  These include the industry and the private sector.  They appear in these sectors respectively as industrial compressed air receivers and domestic hot water storage tanks, other examples of pressure vessels are: diving cylinders, recompression chamber, distillation towers, autoclaves and many other vessels in mining or oil refineries and petrochemical plants, nuclear reactor vessels, habitat of a space ship, habitat of a submarine, pneumatic 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 pressure vessel that is inadequately designed to handle a high pressure constitues a very significant safety hazard. 

Pressure Vessels can theoretically be almost any shape, but shapes made of sections of spheres, cylinders and cones are usually employed.  More complicated shapes have histoically been much harder to analyse for safe operation and are usually far more difficult to construct.  Generally, almost any material with good tensile properties than is chamically stable in the chose application can be employed.

Many pressure vessels are made of steel.  To manufacture a spherical pressure vessel, forged parts would have to be welded together.  Some mechanical properties of steel are increased by forgining, but welding cab sometimes reduce these desirable properties.  In case of welding, in order to make the pressure vessel meet international safety standards, carefully selected stell with a high impact resistanc and corrosion resistant material should also be used.  Some pressure vessels are made of wound carbon fibre, beld in place with a polymer.  Due to the very high tensile strength of carbon fibre these vessels can be very light, but are much trickier to manufacture.  Other very common materials include polymers such as PET in fizzy drinks containers and copper in plumbing.