Is there a category of low-pressure containers among the container types? ? ? What are the container categories? How to divide it? ?

See TSG21-2016, Appendix A.

Internal-pressure vessels are classified according to the magnitude of the pressure they can withstand (gauge pressure) as follows: 1. Vessels operating at normal pressure, with a working pressure of p10000 kPa.

It is classified according to different categories! Pressure vessels are commonly used pressure-bearing equipment in adhesive production. At present, there is no strict and scientific definition for pressure vessels. In a broad sense, any sealed container that is subjected to fluid pressure is considered a pressure vessel. Conditions: What is commonly referred to as a pressure vessel is a vessel that meets all of the following three conditions: 1. It is subject to a pressure of pw>98kPa ； 2. Volume V > 25 L, and pwV > 1.96×104 L·kPa ； 3. The medium is gas, liquefied gas, or liquid with a maximum operating temperature higher than its standard boiling point (excluding hydrostatic pressure). Classification: There are many structural forms and types of pressure vessels, which can be classified from different perspectives. Pressure vessels classified by operating pressure have as their basic load the maximum operating pressure of the medium at a certain temperature. A vessel is referred to as a pressure vessel when the working pressure inside it is greater than the external pressure ； When the internal working pressure is lower than the external pressure, it is called a pressure vessel under external pressure, such as the buffer tank of a vacuum pump. Internal-pressure vessels are classified according to the magnitude of the pressure they can withstand (gauge pressure) as follows: 1. Vessels operating at normal pressure, with a working pressure of p10000 kPa. To facilitate the management of safety technologies as well as supervision and inspection, pressure vessels are classified into three categories based on their pressure tolerance, the hazard level of the medium they contain, and their importance in the production process. 1. A low-pressure vessel containing non-flammable or non-toxic media falls into Category 1 if it meets one of the following conditions ； Low-pressure separation vessels and heat exchange vessels for flammable or toxic media. 2. Containers that fall under one of the following situations are medium-pressure containers in Category II ； Low-pressure containers for highly toxic media ； Low-pressure reactors and storage and transport containers for flammable or toxic media. 3. Containers that fall under one of the following categories are classified as category III high-pressure containers ； Low-pressure vessels containing highly toxic media with pwV>1.96×105 L·kPa, or medium-pressure vessels containing highly toxic media ； Medium-pressure reactors containing flammable or toxic media with pwV>4.9×106 L·kPa, or medium-pressure storage and transport containers with pwV>4.9×106 L·kPa. Based on the production process, pressure vessels can basically be classified into three types. 1. A reaction vessel is primarily used as a container for carrying out physical changes and chemical reactions of a medium. Such as reactors, oil extraction tanks, distillation tanks, gum extraction kettles, steamers, boiling pots, etc ； 2. Heat exchange vessels are primarily used to achieve fluid pressure balance of media, as well as for gas purification, separation, and absorption. Such as separators, filters, buffers, energy storage devices, absorption towers, etc ； 3. Storage and transportation containers are primarily used to store gases, liquids, and liquefied gases. Such as storage tanks, road or rail tank cars, etc ； In addition to the classification methods mentioned above, there are also the following categories: based on the shape of the container, they can be cylindrical, spherical, conical, etc ； Based on the placement method of the container, there are horizontal, vertical, etc. types ； Based on the materials used, they are divided into metal and non-metal types. The above are my personal opinions; I hope they are helpful to you.

There is no strict definition; ultimately, it comes down to the different design, manufacturing, and inspection standards that the equipment follows. Taking the API standard series as an example, differential pressure vessels comply with API 650 when their design pressure is below 2.515 lb/in^2, while low-pressure vessels follow API 620 when their design pressure is less than 15 lb/in^2