Product Description
1. Comparison of Chemical Compositions and Mechanical Properties
| Grade |
Chemical Composition |
Mechanical Properties |
| T11 |
C (0.05 - 0.15%), Mn (0.30 - 0.60%), Si (0.50 - 1.00%), Cr (1.00 - 1.50%), Mo (0.44 - 0.65%) |
Minimum yield strength around 205 - 240 MPa, minimum tensile strength 415 - 515 MPa, elongation at least 20% - 25% |
| T12 |
C (0.05 - 0.15%), Mn (0.30 - 0.60%), Si (0.50 - 1.00%), Cr (0.80 - 1.25%), Mo (0.44 - 0.65%) |
Similar to T11, with yield and tensile strengths within a comparable range and elongation of at least 20% - 25% |
| T22 |
C (0.05 - 0.15%), Mn (0.30 - 0.60%), Si (0.50 - 1.00%), Cr (2.00 - 2.50%), Mo (0.90 - 1.10%) |
Generally has a higher yield strength and tensile strength compared to T11 and T12, with a minimum yield strength around 240 MPa and a minimum tensile strength of 485 - 620 MPa, and elongation of at least 20% |
2. Heat Resistance and Corrosion Resistance
- Heat Resistance: The chromium (Cr) and molybdenum (Mo) in these alloys contribute to their good heat - resistant properties. The higher the chromium and molybdenum content, the better the heat resistance. For example, T22 with a higher Cr and Mo content has better resistance to creep and oxidation at high temperatures than T11 and T12, making it suitable for use in high - temperature sections of boilers and heat exchangers.
- Corrosion Resistance: The chromium in the alloy forms a dense oxide film on the surface of the tube, which provides good corrosion resistance. In addition, the molybdenum helps to improve the resistance to pitting and crevice corrosion. This makes T11, T12, and T22 finned tubes suitable for use in environments where there is a risk of corrosion, such as in contact with water vapor, flue gas, and some corrosive media.
3. Heat Transfer Efficiency
- The finned structure of these tubes significantly increases the heat transfer area. The fins enhance the heat transfer from the inner tube wall to the outer surface, improving the overall heat transfer efficiency. The design of the fin height, pitch, and thickness is optimized according to the specific heat transfer requirements. For example, in a boiler, the finned tubes can effectively transfer the heat from the combustion chamber to the working fluid, increasing the efficiency of the heat exchange process.
4. Application Scenarios
- Boiler Systems: They are widely used in boiler systems, including power plant boilers and industrial boilers. T11, T12, and T22 finned tubes can withstand high temperatures and pressures, and their good heat transfer performance helps to improve the efficiency of the boiler.
- Heat Exchangers: In various heat exchanger applications, such as in the chemical industry, petroleum industry, and HVAC systems, these finned tubes are used to transfer heat between different fluids. Their corrosion resistance and high - temperature resistance ensure the long - term stable operation of the heat exchanger.
- Power Generation: In power plants, they are used in the superheater and reheater sections to increase the steam temperature and improve the thermal efficiency of the power generation cycle.
ASTM A213 specification covers seamless ferritic and austenitic steel boiler, superheater, and heat-exchanger tubes, designated Grades T5, T9, T11, T12, T22, T91, etc. Grades containing the letter H in their designation have requirements different from those of similar grades not containing the letter H. These different requirements provide higher creep-rupture strength than normally achievable in similar grades without these different requirements.
| Standard |
ASTM A213, ASTM A335 |
| Grade |
, ASTM A213 T2,ASTM A213 T5, ASTM A213 T5b,ASTM A213 T5c,ASTM A213 T9, ASTM A213 T11, ASTM A213 T12, ASTM A213 T22, ASTM A213 T23, ASTM A213 T91, ASTM A213 T92, ASTM A335 P1, ASTM A335 P2, ASTM A335 P5, ASTM A335 P9, ASTM A335 P11, ASTM A335 P12, ASTM A335 P22, ASTM A335 P23, ASTM A335 P91, ASTM A335 P92 |
Heat Treatment Requirements of A213 Alloy Steel Seamless Tubes
| Grade |
Heat Treatment Type |
Normalizing Temperature Range F [C] |
Subcritical Annealing
or Tempering
Temperature Range F
[C] |
| T5 (b,c) |
Full or isothermal Anneal |
|
|
| |
Normalize and Temper |
***** |
1250 [675] |
| |
Subcritical Anneal (T5c only) |
***** |
1325 - 1375 [715 - 745] |
| T9 |
Full or isothermal Anneal |
|
|
| |
Normalize and Temper |
***** |
1250 [675] |
| T11 |
Full or isothermal Anneal |
|
|
| |
Normalize and Temper |
***** |
1200 [650] |
| T22 |
Full or isothermal Anneal |
|
|
| |
Normalize and Temper |
***** |
1250 [675] |
| T91 |
Normalize and Temper |
1900-1975 [1040 - 1080] |
1350-1470 [730 - 800] |
| |
Quench and Temper |
1900-1975 [1040 - 1080] |
1350-1470 [730 - 800] |
Detailed Photos
Processing of Production
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