A pressure vessel shall be defined as a container simultaneously meeting the following three criteri
1. Operating pressure ≥ 0.1 MPa (Note 1-2);
2. Geometric volume ≥ 0.03 m³ and internal diameter (for non-circular cross-sections, refers to the geometric dimension of the inner boundary) ≥ 150 mm (Note 1-3);
3. Contains media including gases, liquefied gases, and liquids with maximum operating temperature ≥ their standard boiling points (Note 1-4).
Note 1-2: Operating pressure refers to the maximum gauge pressure attainable at the top of the pressure vessel under normal operating conditions.
Note 1-3: Volume refers to the geometric capacity calculated from design drawing dimensions (excluding manufacturing tolerances) and rounded as required. Internal components permanently attached inside the vessel shall generally be excluded from volume calculations.
Note 1-4: Vessels containing liquids with maximum operating temperatures below their standard boiling points shall also fall under this regulation if the gas-phase space volume ≥ 0.03 m³.
Pressure vessels are categorized into four pressure classes based on design pressure (p):
1. Low Pressure (Code L): 0.1 MPa ≤ p < 1.6 MPa
2. Medium Pressure (Code M): 1.6 MPa ≤ p < 10.0 MPa
3. High Pressure (Code H): 10.0 MPa ≤ p < 100.0 MPa
4. Ultra-High Pressure (Code U): p ≥ 100.0 MPa
Pressure vessels are classified into four categories based on their functional principles in production processes:
Primarily used for physical/chemical reactions of media. Examples include reactors, autoclaves, decomposition kettles, vulcanizing tanks, polymerization vessels, high-pressure digesters, synthetic towers, convertors, cooking vessels, spherical digesters, and gas generators.
2. Heat Exchange Pressure Vessels (Code E):
Primarily used for thermal energy exchange of media. Examples include shell-and-tube waste heat boilers, heat exchangers, coolers, condensers, heaters, sterilizers, dyers, drying cylinders, evaporators, solvent preheaters, steamers, desolventizers, electrothermal steam generators, and gas generator water jackets.
3. Separation Pressure Vessels (Code S):
Primarily used for fluid pressure balancing, buffering, and gas purification/separation. Examples include separators, filters, oil collectors, surge tanks, scrubbers, absorption towers, copper wash towers, drying towers, stripping towers, steam headers, and deaerators.
4. Storage Pressure Vessels (Code C; Spherical Tanks Code B):
Primarily used for storing/containing gases, liquids, or liquefied gases. Examples include various types of storage tanks.