A pressure vessel is a closed container designed to hold gases or liquids at a pressure different from the ambient pressure.This pressurised environment combined with heat and or mass transfer bring about the reactions required for the various operations in the Oil and Gas and Chemical Process Industry.
The pressure differential of ill designed pressure vessels have led to fatalities in the history of pressure vessel development and operationand hence pressure vessel design, manufacture, and operation are regulated by engineering authorities backed by legislation.
The legal definition of pressure vessel varies from country to country, but always involves the maximum safe pressure at the operating conditions that the vessel is designed.Pressure Vessels are designed and constructed factoring in a safety factor, corrosion allowance, minimum design temperature (for brittle fracture), and involve nondestructive testing, such as ultrasonic testing, radiography, and pressure tests, usually involving water, also known as a hydrotest, but could be pneumatically tested involving air or another gas.
Observance of the rules contained in tha National or other accepted international codes is a statutory requirement.