Closed equipment containing gas or liquid and bearing certain pressure, Its range for maximum working pressure is greater than or equal to 0.1 MPa (gauge pressure) gas, liquefied gas and the highest standard of working temperature is higher than or equal to the boiling point of liquid, volume is greater than or equal to 30 l and internal diameter (non circular cross section refer to the section within the largest geometry) greater than or equal to 150 mm stationary containers and containers;

A pressure vessel is a closed device that holds gas or liquid and bears certain pressure. In order to more effectively implement scientific management and safety supervision, the pressure vessels are divided into three types according to working pressure, medium harmfulness and their role in production in the "pressure vessel safety supervision Rules".