Pressure vessels most often contain fluids, vapors or gases at pressure levels greater than that of atmospheric pressure. Pressure vessels contain a wide variety of substances used for various industrial applications including the chemical pressure vessels, pharmaceutical pressure vessels, food pressure vessels and beverage pressure vessels, oil pressure vessels, and fuel, pressure vessels and plastic industries. The substance contained and the industrial application of the pressure vessel determine such design components as pressure vessel material, pressure vessel size, pressure vessel shape, pressure vessel temperature and pressure vessel pressure level. Pressure vessel creation and maintenance consist of structured steps in which the above factors are determined. When a substance is stored under pressure, the potential for rupture and leakage exists. Improper pressure vessel design and maintenance increase the risk of pressure vessel failure, posing a serious safety hazard. This risk increases when pressure vessel contents are toxic or gaseous substances. Engineers take precautions when creating a pressure vessel to limit the occurrence of vessel failure. The division of pressure vessel creation into steps, which include design, construction, testing and inspection, keeps safety hazards to a minimum.
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Last Updated: June 16, 2007
Last Updated: June 16, 2007
What are Pressure Vessels?
In the pressure vessel design process, engineers determine the logistics of pressure vessel creation. Engineers must determine the pressure level, temperature, material components, size and shape. Engineers also consider the corrosion and abrasion potential of the pressure vessel before deciding these factors. Pressure levels are also taken into account before deciding upon a material and shape. Pressure vessels range from a few hundred pounds per square inch (psi) to measuring up to 150,000 psi. Temperature must also be considered before deciding on a material, as materials like steel are susceptible to damage from exposure to extreme temperatures. Materials can include carbon alloy steel, stainless steel, titanium, zirconium, aluminum, nickel alloys and niobium. Sizes range from small pressure vessels holding only a few ounces of a substance to very large pressure vessels with up to a 95,000-gallon capacity. Most pressure vessels are cylindrical; however, contents under extremely high pressure are often placed in stronger spherical vessels.
Because of the above factors and the fact that pressure vessels can have a temperature range that exceeds 750°F, safety is of large importance. There are standard regulations and formulas to which pressure vessel designs adhere in order to avoid potential hazards associated with pressure containment within pressure vessels. The American Society of Mechanical Engineers (ASME) provides a Boiler and Pressure Vessel Code on which engineers base pressure vessel design. Although the ASME Code remains the most common standard, engineers also follow other codes, such as that of the American Petroleum Institute (API). Rigorous analyses for complex pressure vessels are created when standard design rules do not apply. In such instances, engineers conduct intensive mathematical and scientific analyses to ensure design and construction methods meet the stringent requirements of pressure vessels: material, size, shape, temperature and pressure level of the pressure vessel, as well as personal preferences.
Engineers usually create pressure vessels using one of three processes. Forging involves the formation of metal parts through the application of heat and pressure. Welding involves melting two similar metals together. Brazing involves the joining of metals by filling the space between them with a nonferrous metal. Testing of the pressure vessel ensures design technique success, proper vessel operation and certification approval. Regular inspection remains necessary to ensure that the vessel continues to meet industrial standards and safety requirements. The National Board of Boiler and Pressure Vessel Inspectors remains the worldwide standard for pressure vessel inspection, alteration and repair.
Because of the above factors and the fact that pressure vessels can have a temperature range that exceeds 750°F, safety is of large importance. There are standard regulations and formulas to which pressure vessel designs adhere in order to avoid potential hazards associated with pressure containment within pressure vessels. The American Society of Mechanical Engineers (ASME) provides a Boiler and Pressure Vessel Code on which engineers base pressure vessel design. Although the ASME Code remains the most common standard, engineers also follow other codes, such as that of the American Petroleum Institute (API). Rigorous analyses for complex pressure vessels are created when standard design rules do not apply. In such instances, engineers conduct intensive mathematical and scientific analyses to ensure design and construction methods meet the stringent requirements of pressure vessels: material, size, shape, temperature and pressure level of the pressure vessel, as well as personal preferences.
Engineers usually create pressure vessels using one of three processes. Forging involves the formation of metal parts through the application of heat and pressure. Welding involves melting two similar metals together. Brazing involves the joining of metals by filling the space between them with a nonferrous metal. Testing of the pressure vessel ensures design technique success, proper vessel operation and certification approval. Regular inspection remains necessary to ensure that the vessel continues to meet industrial standards and safety requirements. The National Board of Boiler and Pressure Vessel Inspectors remains the worldwide standard for pressure vessel inspection, alteration and repair.
