In the industrial production of stainless steel pressure vessels, equipment with specific process functions and capable of withstanding certain pressures is called a pressure vessel. Storage and transportation containers, reaction containers, heat exchangers, and separation containers are all pressure vessels. In order to distinguish it from general containers (atmospheric pressure containers), only containers that meet the following three conditions simultaneously are called pressure vessels:

High working pressure ≥ 9.8104 Pa (1 kgf/cm2); Volume ≥ 25L, and the product of working pressure and volume ≥ 200L Kgf/cm2(L.Pa); The medium is gas, liquefied gas, or liquid with a working temperature higher than the standard boiling point. Pressure vessels have a wide range of applications. It is equipment that plays an important role in various sectors of the national economy, such as the petrochemical industry, energy industry, scientific research, and military industry. Stainless steel pressure vessels generally consist of six main parts: cylinder, flange, head, sealing element, opening and connecting pipe, and support. In addition, it is equipped with safety devices, meters, and internal components for different production processes.

Due to sealing, pressure bearing, and medium, pressure vessels are prone to explosions, fires, and accidents that endanger the safety of personnel, equipment, and property, as well as pollute the environment. At present, countries around the world classify it as an important product for supervision and inspection, which is carried out by specialized institutions designated by the state in accordance with national regulations and standards for supervision, inspection, and technical testing.