Pressure vessel refers to a closed container containing a certain medium or vacuum. According to the principle of action in the production process, pressure vessels can be divided into four types: reaction pressure vessels, heat exchange pressure vessels, separation pressure vessels, and storage pressure vessels. Pressure vessels include liquefied gas tanks, acetylene tanks, oxygen tanks, boilers, pressure cookers, gas pump gas storage tanks, etc.

1. Pressure vessels are widely used. It plays an important role in various sectors of the national economy such as petrochemical industry, energy industry, scientific research and military industry. The pressure vessel generally consists of six major parts, such as cylinder body, head, flange, sealing element, opening and connecting pipe, and support, which constitute the container body. In addition, it is also equipped with safety devices, meters and internal parts for completely different production processes. Due to the reasons of sealing, bearing pressure and medium, pressure vessels are prone to explosion, combustion and fire, which endanger the safety of personnel, equipment and property, and pollute the environment. All countries in the world regard it as an important supervisory inspection product, and the specialized agency designated by the state conducts supervision, inspection and technical inspection in accordance with the regulations and standards stipulated by the state.
2. There are many classification methods for pressure vessels. From the perspective of use, manufacture and supervisory inspection, there are the following types. Pressure vessels (1) are classified into low-pressure vessels, medium-pressure vessels, high-pressure vessels and ultra-high-pressure vessels according to their pressure levels.
(2) According to the packaging medium, it is divided into: non-flammable, non-toxic; flammable or toxic; highly toxic.
(3) According to the different functions in the process, it is divided into:
①Reaction vessel: A vessel used to complete the physical and chemical reactions of the medium.
②Heat exchange container: The container used to complete the heat exchange of the medium.
③Separation container: It is a container used to complete the mass exchange of medium, gas purification, solid, liquid and gas separation.
④Storage and transportation container: a container used to hold liquid or gas materials, storage and transportation media or to balance and buffer pressure