Classification of Pressure Vessels in China

Classification of Pressure Vessels in China

A pressure vessel refers to a container designed to store liquids or gases at a certain pressure. Made of metal or nonmetal materials, the pressure vessel has extremely high requirements on security to make liquids or gases stored with safety.

The pressure vessel must be the sealed vessel able to withstand the pressure load, and is used for the process of production such as reaction, mass transfer, separation, storage, etc. A pressure vessel plays a vital role in certain industries, such as petrochemicals, energy and scientific research, important for every section of the national economy.

The pressure differential between the internal pressure and the external pressure is dangerous. In the development history of the pressure vessel, various fatal accidents happened due to defective designs, poor workmanship and misoperation. As a result, the design, manufacture and operation of the pressure vessel are regulated by engineering authorities in different countries. The regulation and parameter of the pressure vessel can be different in different countries, including maximum working pressure and maximum working temperature.

For the implementation of scientific management and safety supervision, Supervision Regulation on Safety Technology for Stationary Pressure Vessel (hereinafter referred to as Regulation) was issued by General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on August 31st, 2009, and was enforced from December 1st, 2009.

The classification of pressure vessels in China should be in accordance with the Regulation TSG R0004-2009. At first, the pressure vessel needs to be divided into two categories according to media, and then be classified into type I, type II and type III according to its pressure and volume. Moreover, the old classification, directly dividing the pressure vessel into the first class, the second class and the third class, is invalid now.  

Pressure vessels can be classified through many methods from the perspectives of their functions, production and supervision.

According to different working pressures of the pressure vessel, a pressure vessel can be defined as the low-pressure pressure vessel, the medium pressure vessel, the high pressure vessels or the ultrahigh pressure vessel.
1. Low-pressure Vessel (Code L)  0.1MPa<P<1.6MPa
2. Media-pressure Vessel (Code M)  1.6MPa≤P<10MPa  
3. High-pressure Vessel (Code H)  10MPa≤P<100MPa
4. Ultrahigh Pressure Vessel (Code U)  P≥100MPa

According to the media of the pressure vessel, a pressure vessel can be defined as the non-flammable and non-toxic pressure vessel, the toxic pressure vessel, the flammable pressure vessel, the highly toxic pressure vessel.

According to the different functions, pressure vessels can be divided into the following four types.
1. A reaction vessel is a container in which physical reactions and chemical reactions occur among media.
2. A heat exchanger is a container in which two or more media exchange their heat.
3. A separator is a container in which mass transfer, gas purification, gas-liquid separation, solid-liquid separation and solid-gas separation occur among different media. 
4. A storage tank is a container used for having balanced and buffer effects on the pressure, as well as used for gas storage, liquid storage, etc.