The quality and specifications of materials for pressure vessels should comply with TSG21-2016 "Safety Technical Supervision Regulations for Fixed Pressure Vessels". The material production unit should provide the user with a quality certificate (original) according to the relevant standards, and make a clear and firm steel stamp or other mark in a prominent position on the material, which should at least include the material manufacturing standard code, material grade and specifications, furnace (batch) number, national safety supervision agency recognition mark, name of the material production unit, and inspection seal mark.

       1、Pressure VesselThe quality and specifications of materials used for pressure vessels should comply with the provisions of TSG21-2016 "Safety Technical Supervision Regulations for Fixed Pressure Vessels". The material production unit should provide the user with a quality certificate (original) according to the relevant standards, and make clear and firm steel stamp marks or other marks on obvious parts of the material, which should include at least the material manufacturing standard code, material grade and specifications, furnace (batch) number, national safety supervision agency recognition mark, name of the material production unit, and inspection seal mark.

       2. In addition to considering mechanical properties and bending properties, the selection of materials for pressure vessels should also consider compatibility with the medium. The phosphorus content (melting analysis, same below) of special steel for pressure vessels should not exceed 0.030%, and the sulfur content should not exceed 0.020%. If carbon steel boiling steel plates and carbon steel quiet steel plates are used to manufacture pressure vessels (except for glass-lined pressure vessels), they should comply with GB150.2-2011 "Pressure Vessels Part 2: Materials". Carbon steel boiling steel plates and Q235A steel plates must not be used to manufacture pressure vessels that are directly heated by flames.

       3. For welded structural pressure vessels, the carbon steel and low-alloy steel of the main pressure-bearing components should not have a carbon content greater than 0.25%.

       4. The mechanical properties, bending properties, and impact test requirements of materials (steel plates, forgings, steel pipes, bolts, etc.) used for steel pressure vessels should comply with relevant national regulations.

       5. Carbon steel and low-alloy steel plates used for manufacturing pressure vessel shells should follow the ultrasonic testing requirements in TSG21-2016 "Safety Technical Supervision Regulations for Fixed Pressure Vessels", 2.2.1.4. Any of the following conditions should be subjected to ultrasonic testing on a sheet-by-sheet basis: a. Pressure vessels containing extremely or highly toxic media; b. Pressure vessels containing liquefied petroleum gas with hydrogen sulfide content greater than 100mg/L; c. Pressure vessels with a maximum working pressure greater than or equal to 10MPa; d. Steel plates that are required to undergo ultrasonic testing sheet-by-sheet as specified in GB151-2014 "Heat Exchangers", GB12337-2014 "Steel Spherical Storage Tanks", and other national and industry standards.

       6. Mobile pressure vessels. The ultrasonic testing of steel plates should be conducted according to NB/T47013.3-2015 "Non-destructive Testing of Pressure Equipment Part 3: Ultrasonic Testing". According to TSGR0005-2011 "Safety Supervision Regulations for Mobile Pressure Vessels", for the tank body of mobile pressure vessels, two steel plates should be randomly selected from each batch for Charpy (V-notch) low-temperature impact tests, with a test temperature of -20℃ or as specified in the drawings, and the sampling direction of the test pieces should be transverse. The low-temperature impact energy absorption index should comply with relevant regulations.

       7. Requirements for cast iron used in pressure vessels. Must be selected within the scope of the corresponding national standards, and the material grade used for casting should be indicated in the product quality certificate. The design pressure and design temperature should comply with the following provisions: a. The design pressure of pressure vessels made of gray cast iron shall not exceed 0.8MPa, and the design temperature shall be 0 to 250℃; b. The design pressure of pressure vessels made of ductile iron and malleable iron shall not exceed 1.6MPa, and the design temperature shall be -10 to 350℃.

       8. The cast steel materials used for pressure-bearing components of pressure vessels should be selected according to TSG21-2016, and the material grade used for casting should be indicated in the product quality certificate. The body and heads of pressure vessels should not use cast steel materials (except for those with prior experience and approved by provincial or national safety supervision agencies).

       9. The requirements for non-ferrous metals (referring to aluminum, titanium, copper, nickel, and their alloys) used in pressure vessels are as follows: Non-ferrous metals used for manufacturing pressure vessels should be selected according to TSG21-2016. If there are special requirements for non-ferrous metals, they should be indicated in the design drawings or corresponding technical conditions. The manufacturing unit must establish a strict material storage system and have a dedicated place for storage. The impact test requirements for materials used in non-ferrous metal pressure vessels should comply with the relevant standards. The weld joints of non-ferrous metal pressure vessels should be machined using mechanical methods, and their surfaces should not have defects such as cracks, delamination, and slag inclusion.

       10. According to the provisions of TSG21-2016, aluminum and aluminum alloys used for pressure-bearing components of pressure vessels should meet the following requirements: The design pressure should not exceed 8MPa, and the design temperature range is -269 to 200℃. When the design temperature exceeds 65℃, aluminum alloys with a magnesium content greater than or equal to 3% are generally not selected.

       11. According to the provisions of TSG21-2016, copper and copper alloys used for pressure-bearing components of pressure vessels should generally be in an annealed state.

       12. According to the provisions of TSG21-2016, titanium materials (referring to industrial pure titanium, titanium alloys, and their composite materials, the same below) used for manufacturing pressure-bearing components of pressure vessels should meet the following requirements: a. Design temperature. Industrial pure titanium should not exceed 230℃, titanium alloys should not exceed 300℃, and titanium composite plates should not exceed 350℃; b. Titanium materials used for manufacturing pressure vessel shells should be used in an annealed state; c. The forming of titanium pressure vessel heads should use hot forming or cold forming followed by hot straightening. For formed titanium-steel composite plate heads, ultrasonic testing should be performed; d. Titanium pressure vessels generally do not require heat treatment. For titanium vessels used in stress corrosion environments or those made from thick plates, stress relief annealing should be performed after welding or hot processing. Titanium-steel composite plates should undergo stress relief annealing after explosive bonding; e. The welds of titanium pressure vessels should undergo penetrant testing.

       13. According to the provisions of TSG21-2016, the use of nickel materials (referring to nickel and nickel-based alloys and their composite materials, the same below) for manufacturing pressure-bearing components of pressure vessels should meet the following requirements: a. Design temperature. Annealed pure nickel materials should not exceed 650℃, nickel-copper alloys should not exceed 480℃, nickel-chromium-iron alloys should not exceed 650℃, and nickel-iron-chromium alloys should not exceed 900℃; b. Nickel materials used for the main pressure-bearing components of pressure vessels should be used in an annealed state, and pure nickel pipes for heat exchangers should be used in a stress relief annealed state; c. When nickel materials for pressure vessel heads are hot formed, the heating temperature should be strictly controlled; for formed nickel-steel composite plate heads, ultrasonic testing should be performed; d. The heating temperature and atmosphere of nickel materials during hot forming should be strictly controlled to prevent sulfur embrittlement; e. Nickel pressure vessels generally do not require post-weld heat treatment. If there are special requirements, post-weld heat treatment should be specified in the drawings; nickel-steel composite plates should undergo stress relief annealing after explosive bonding; f. The welds of nickel pressure vessels should undergo magnetic particle or penetrant testing.

       14. According to the provisions of TSG21-2016, the pressure components of pressure vessels using foreign materials must meet the following requirements: a. Materials should be selected from those allowed by foreign pressure vessel standards and have existing usage examples abroad. Their usage scope should comply with the relevant regulations and standards of the material's producing country, and there should be a quality certificate for the material; b. The manufacturing unit must conduct welding process evaluation and welder examination before the first use, and re-examine the chemical composition and mechanical properties. Only after meeting the usage requirements can the materials be used for manufacturing; c. Technical requirements should generally not be lower than the technical indicators of corresponding domestic materials; d. For materials that are used for the first time domestically and have a specified lower limit of tensile strength greater than or equal to 540MPa, approval procedures should be handled as required.

       15. According to the provisions of TSG21-2016, the main pressure components of pressure vessels using newly developed materials (including imported materials that have no application examples domestically or abroad) or materials not listed in standards such as GB150-2011 "Pressure Vessels" for trial manufacturing of pressure vessels, the material development and production unit must submit test verification data and third-party inspection reports to the National Pressure Vessel Standardization Technical Committee for technical review and obtain a certificate of permission for trial use issued by the committee (which should specify the usage conditions), and handle approval procedures as required.

       16. According to the provisions of TSG21-2016, the welding materials used for manufacturing pressure vessel pressure components should be manufactured, inspected, and selected according to the corresponding standards. Welding materials must have a quality certificate and clear, firm markings.

       17. According to the provisions of TSG21-2016, the materials for manufacturing pressure vessels are mainly selected based on the process conditions of the vessel (pressure, temperature, medium characteristics) and the vessel manufacturing method. The overall requirements are good plasticity, good toughness, and appropriate strength limits. For welded vessels, materials should have good weldability, and for vessels containing corrosive media, materials should have strong corrosion resistance. The mass fraction of carbon in Q235AF boiling steel is about 0.14% to 0.22%, which has good plasticity, a tensile strength greater than 380MPa at room temperature, a yield strength greater than 240MPa, and an elongation greater than 25%. However, due to incomplete boiling deoxidation, the steel may contain iron oxide or bubbles, resulting in a loose structure and poorer quality. In particular, self-brittleness may occur after welding over time, and it is generally not suitable for manufacturing welded pressure vessels.