Summary of material requirements based on the operating temperature of pressure vessels

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General requirements: 1. When carbon steel and carbon-manganese steel are used at temperatures above 425°C for extended periods, the tendency of the carbide phases in the steel to graphitize must be taken into account. 2. When austenitic steel is used at temperatures above 525°C, its carbon content should be no less than 0.04%. 3. When austenitic steel is used at temperatures equal to or above -196°C, the impact test can be omitted. Below -196°C to -253°C, the impact test requirements are specified in the design documents. Steel plates: 1. Carbon steel and low-alloy steel plates. (1) For Q370R steel plates intended for use at design temperatures above 200°C, and for 18MnMoNbR, 13MnNiMoR, and 12Cr2M01VR steel plates intended for use at design temperatures above 300°C, the design documents shall require that high-temperature tensile tests at the design temperature be conducted on the steel plates in batches. (2) As required by the design documents, drop hammer tests may be conducted additionally on steel plates with a thickness greater than 36 mm and a minimum standard tensile strength of 540 MPa or higher, as well as on steel plates intended for use at design temperatures below -40°C. The tests are conducted in accordance with GB/T 6803, using P-2 type specimens; the acceptance criteria for the temperature of plasticity transition (NDT) are specified in the design documents. (3). The usage requirements for the Q235B and Q235C steel plates specified in GB/T 3274-2007 \"Hot-rolled heavy plates and strips of carbon structural steel and low-alloy structural steel\" are as follows: The operating temperature for these steel plates is 20°C to 300°C for Q235B plates℃ ； The Q235C steel plate ranges from 0°C to 300°C. 2. High-alloy steel plates (1). Lower operating temperature limit: 0 for ferritic-type plates℃ ； Austenite-ferrite type steel plates are -20℃ ； (2). Titanium-steel composite plate: The lower limit of the operating temperature for titanium-steel composite plates is determined by the standards regarding the base material, while the upper limit is 350℃ ； (3). Copper-steel composite wrench: The lower limit of the operating temperature for copper-steel composite plates is determined by the standards regarding the base material, while the upper limit is 200℃ ； Steel pipes 1. Carbon steel and low-alloy steel pipes (1). The standards, service conditions, and allowable stresses for steel pipes are specified in the table below. For steel pipes with a wall thickness greater than 30 mm and those used at temperatures below -20°C, normalizing as specified in the table cannot be replaced by hot rolling at a final rolling temperature that corresponds to the normalizing temperature. The steels used for steel pipes designed for temperatures below -40°C in the table below shall all undergo secondary refining. (2). Provisions for the use of 10, 20 steel and Q345D steel pipes in GB/T 8163: The minimum operating temperatures for 10, 20, and Q345D steel pipes are -10°C, 0°C, and -20°C respectively℃ ； (3) The usage requirements for steel pipes of various grades specified in GB 9948 are as follows: the minimum operating temperatures for 10 and 20 grade pipes are -20°C and 0°C respectively. (4) The usage requirements for steel pipes of various grades specified in GB 6479 are as follows. The minimum operating temperatures for 20 and 16Mn steel pipes are 0°C and -20°C respectively. (5) For steel pipes used at temperatures below -20°C, the steel grade, operating condition, and impact test temperature (i.e., the minimum operating temperature for the steel pipe) are shown in the table below. For 16Mn steel, the chemical composition shall meet the requirements of P≤0.025% and S≤0.012%. Steel pipes with an outer diameter of not less than 70 mm and a wall thickness of not less than 6.5 mm are subjected to impact tests at -40°C, and the average impact energy of 3 longitudinal standard specimens shall be not less than 34 J. (6). When using steel bars of 10 steel and 20 steel with a diameter not exceeding 50 mm as specified in GB/T 699 to manufacture fittings, the applicable requirements are as follows: the minimum operating temperatures for fittings made of 10 steel and 20 steel are -10°C and 0 respectively℃ ； When P≤0.030% and S≤0.020% for 10 steel pipes, the lower operating temperature limit is -20℃ ； 2. High-alloy steel pipes: Pipes of each grade specified in GB/T 21832 and GB/T 21833 are suitable for temperatures of -20°C. Steel forgings 1. Carbon steel and low-alloy steel forgings (1) For steel forgings used in low-temperature environments where the operating temperature is below -20°C and the nominal thickness is greater than 200 mm, grade III or grade IV forgings should be selected. (2). For the design of 20MnMoNb, 20MnNiMo, 12Cr2Mo1V, and 12Cr3Mo1V grades III or IV steel forgings intended for use at temperatures above 300°C, the design documents shall specify that high-temperature tensile tests at the design temperature be conducted on the steel forgings in batches (for grade III) or individually (for grade IV). 2. High-alloy steel forgings: The minimum operating temperature for steel forgings is as follows: for ferritic S11306 steel forgings, it is 0℃ ； Austenite-ferrite type S21953, S22253, and S22053 steel forgings are -20℃ ； Steel bars for studs (including bolts) and nuts 1. Carbon steel and low-alloy steel bars The minimum operating temperature limits and related technical requirements for carbon steel and low-alloy steel studs shall be in accordance with the following provisions: (1) For 20 steel studs, it is -20℃ ； 35, 40MnB, 40MnVB and 40Cr steel studs are 0℃ ； Other steel grade studs are at -20°C. (2) When stud bolts made of 30CrMoA, 35CrMoA, and 40CrNiMoA steels are used at temperatures below -20°C, low-temperature impact tests at such operating temperatures shall be conducted. (3) For 30CrMoA and 35CrMoA stud steels used at temperatures below -40°C to -70°C, the phosphorus and sulfur contents in their chemical composition (as determined by melting analysis) should be P≤0.020% and S≤0.010%. For 40CrNiMoA stud steels and 30CrMoA stud steels used at temperatures below -70°C to -100°C, the phosphorus and sulfur contents in their chemical composition (as determined by melting analysis) should be P≤0.015% and S≤0.008%. 2. High-alloy steel rods (1) The minimum operating temperature for high-alloy steel studs is specified as follows: for S42020 steel studs, it is 0℃ ； (2) The steel rods for S30408 studs that have undergone solution treatment followed by strain strengthening should be selected in accordance with GB/T 4226. When the operating temperature is below -100°C, the stud blanks must undergo low-temperature impact testing at that temperature, with the low-temperature impact energy value KV2 being ≥ 41 J ；