The definition and application of pressure vessels

Pressure vessels generally refer to closed containers used in industrial production to complete processes such as reactions, heat transfer, mass transfer, separation, and storage, and to withstand pressures above 0.1 MPa of gauge pressure.

The 'Regulations on Safety Supervision of Special Equipment' clearly states that the definition of pressure vessels is:

Pressure vessel

A pressure vessel refers to a closed device that holds gas or liquid and bears a certain pressure. Its scope is defined as a maximum working pressure greater than or equal to 0.1 MPa (gauge pressure). Fixed and mobile containers for gases, liquefied gases and liquids with a maximum working temperature higher than or equal to the standard boiling point, where the product of pressure and volume is greater than or equal to 2.5 MPa·L; Gas cylinders containing gases, liquefied gases and liquids with a standard boiling point equal to or lower than 60℃ that have a nominal working pressure greater than or equal to 0.2 MPa (gauge pressure) and a product of pressure and volume greater than or equal to 1.0 MPa·L; Oxygen chambers, etc.

Application of pressure vessels:

Pressure vessels were mainly used in the chemical industry in the early days, and the pressure was mostly below 10 megapascals. After the emergence of high-pressure production processes such as ammonia synthesis and high-pressure polyethylene, the pressure that pressure vessels are required to withstand has been increased to over 100 megapascals.

With the development of the chemical and petrochemical industries, the working temperature range of pressure vessels is becoming increasingly wide. The emergence of new working media also requires that pressure vessels be resistant to medium corrosion. The scale of many process facilities is getting larger and larger, and the capacity of pressure vessels is also constantly increasing accordingly. Since the 1960s, the development of nuclear power plants has put forward higher safety and technical requirements for reactor pressure vessels, which has further promoted the development of pressure vessels. For example, the development of the coal conversion industry requires high-temperature pressure vessels with a single weight of several thousand tons. The application of fast neutron proliferation reactors requires the solution of pressure vessels that can withstand high temperatures and liquid sodium corrosion. The development of Marine engineering requires external pressure vessels that can work at depths of several hundred to several thousand meters underwater.

A pressure vessel, in English: pressure vessel, refers to a closed device that holds gas or liquid and bears a certain pressure. In order to implement scientific management and safety supervision and inspection more effectively, China's 'Safety Supervision Regulations for Pressure Vessels' classifies pressure vessels into three categories based on working pressure, the hazard of the medium, and their role in production.

And different regulations have been made for each category of pressure vessels in the design, manufacturing process, as well as the inspection items, contents and methods. The safety and quality licensing system for imported goods has been implemented for pressure vessels. Goods that have not obtained the import safety and quality licensing certificate are not allowed to be imported. According to the latest TSG21-2016 'Safety Technical Supervision Regulations for Fixed Pressure Vessels', the vessels should first be classified into the first group of media and the second group of media based on the medium, and then into categories I, II, and III based on pressure and volume. The so-called first, second, and third categories in the old pressure vessel regulations are no longer applicable.

Pressure vessels are all closed containers capable of withstanding pressure. Pressure vessels have an extremely wide range of applications and play an important role in many sectors such as industry, civil use, military industry, as well as in many fields of scientific research. Among them, pressure vessels are most widely used in the chemical industry and petrochemical industry. The pressure vessels applied in the petrochemical industry alone account for about 50% of the total number of pressure vessels. Pressure vessels are mainly used in the fields of chemical engineering and petrochemicals for processes such as heat transfer, mass transfer, and reaction, as well as for storing and transporting pressurized gases or liquefied gases. It also has extensive applications in other industrial and civil fields, such as air compressors. All kinds of special compressors and auxiliary equipment of refrigeration compressors (coolers, buffers, oil-water separators, gas storage tanks, evaporators, liquid refrigerant storage tanks, etc.) all belong to pressure vessels.