Pressure vessels, also known as ASME pressure tanks, are a type of industrial equipment that are used for storing vapors, gases, or fluids at a pressure different than the ambient pressure. As they have to withstand operating pressure of more than 15 psi, they have to follow and pass stringent government regulations.
Pressure vessels have application in mining, refineries, and military equipment such as submarines. They are used for storing a number of gases like chlorine, petroleum, and ammonia. For different applications, different types of vessels are available such as air pressure tanks, vacuum tanks, and heat exchangers.
Pressure vessels may look like a simple cylindrical container; however, over time, they have played an important part in industrialization. It is documented that pressure vessels were used even in the sixteenth century for hauling up heavy weights underwater. In 1495, Leonardo da Vinci came with the idea and designed air pressured containers for lifting purposes. However, the present day application of pressure vessels was not devised until the advent of steam engines. In steam engines, pressure vessels were used as boilers, where steam was produced and contained for powering the cylinder.
In all external combustion engines, pressure vessels were major equipment. However, pressure vessels were also the most unreliable part of external combustion engines, as the technology for manufacturing pressure vessels was in the formative stage. Moreover, the quality of materials used for making vessels was poor. The failure of pressure vessels was usually catastrophic, causing damage to the machines and killing operators. They were the source of explosions in an array of industries on a daily basis.
The first effort to modernize pressure vessels and improve their safety emerged in the United States. In 1911, American Society of Mechanical Engineers (ASME), which was established in 1880, came up with the idea of standardizing codes for making pressure vessels and presented the Boiler and Pressure Vessel Code (BPVC). In 1914, first rules and codes for constructing pressure vessels were printed.
Since industries needed pressure vessel that could withstand 10,000 psi, in 1919, a new design of pressure vessels came on the market. To endure such high pressure, steel wires were spirally wounded around the tank and rods gave additional reinforcement. With this design, there was no rupture of the pressure vessels even under stressful conditions.
At the same time, welding replaced rivets, as industries, such as chemical plants and petroleum refineries, needed pressure vessels that could endure high temperature too. BPVC recognized how welding could make pressure vessels stronger and thus, safer, so welding was included in the code. It was the beginning of the modern manufacturing technique, as nearly all of them use welding for joining metal plates in vessels.
Over time, to make pressure vessels safer, different testing techniques and methods were developed, and it became mandatory that all pressure vessels go through an examination. Traditional tests are mainly destructive; however, the modern tests are non-destructive. These new tests include radiography and phased array ultrasonic. Moreover, for making pressure vessels safer, assessing methods have also played a major role. Modern assessing methods, such as finite element analysis, can identify stress points.