ASTM A213/ASME SA213
T92（NF616）Seamless Steel Tubes
ASTM A213/ASME SA213 T92（NF616）Seamless Steel Tubes
Short Description:
SA213 T92 steel tubes can partially replace TP304H and TP347H austenitic stainless steel pipes to manufacture sub-critical, super-critical, or even super-supercritical power plant boilers with metal wall temperatures not exceeding 650℃.
Introduction of SA213 T92 (NF616) steel
T92 (NF616) steel is Nippon Steel based on T91. It has further improved the composition, adopted composite-multiple strengthening methods, appropriately reduced the content of Mo and added W, and formed W-Mo with W as the main component. Composite solid solution strengthening, adding element N to form interstitial solid solution strengthening, adding elements such as V, Nb, and N to form carbonitride dispersion precipitation strengthening, and adding a small amount of B (0.001-0.006%) to form grain boundary strengthening of element B, and T91 The same high Cr content guarantees the same oxidation resistance and corrosion resistance as T91.
T92 steel, like T91 steel, has a better thermal expansion coefficient and thermal conductivity than austenitic steel. It has excellent long-term strength, high allowable stress, good toughness and weldability, and stable structure and performance before and after aging. . The allowable stress is higher than T91 steel, and the allowable stress at 650 ° C is 1.6 times that of T91 steel; and the steam oxidation resistance is better, which is basically the same as T91 steel. The temperature equal to TP347H is 625 ℃. When the temperature is lower than 625 ℃, the lasting strength of T92 steel is higher than TP347H.
Manufacture:Seamless process ,Hot-finished or Cold-finished
Wall thickness(WT): 7.5mm——32.0 mm.
Outer diameter (OD): 89.9 mm——452.0 mm
Length: 6M or specified length as required.
Ends: Plain End, Beveled End, Threaded
Application of SA213 T92 (NF616) steel tubes
SA213 T92 steel tubes have excellent performance, and the use temperature can reach 650 ℃. It can partially replace TP304H and TP347H austenitic stainless steel tubes to manufacture sub-critical, super-critical, or even super-supercritical power plant boilers with metal wall temperatures not exceeding 650 ° C, such as high-temperature superheaters, reheater tubes, and main steam tubes. To avoid or reduce dissimilar steel joints and improve the running performance of steel tubes. If used in subcritical boilers, it can be used instead of TP347H and T91 thick-walled steel tubes.
Chemical composition
| Standard | Grade | Chemical composition（%） | |||||
| C | Mn | Si | P | S | Cr | ||
| SA213 | T92 | 0.07-0.13 | 0.30-0.60 | ≤0.50 | ≤.020 | ≤.010 | 8.0-9.5 |
| Nippon Steel | NF616 | ≤0.15 | ≤1.00 | ≤0.50 | ≤.020 | ≤.010 | 8.0-13.0 |
| Ni | Mo | V | Nb | N | Al | ||
| SA213 | T92 | ≤0.40 | 0.30-0.60 | 0.15-0.25 | 0.04-0.09 | 0.03-0.07 | ≤.040 |
| Nippon Steel | NF616 | — | ≤1.00 | 0.10-0.30 | ≤0.10 | 0.02-0.15 | ≤.040 |
Note 1: It also contains W (tungsten) and B (boron). In the SA213 standard, the specified value of W is 1.50-2.0%, and the specified value of B is 0.001-0.006%.
Note 2: It also contains W (tungsten) and B (boron). The N specified value of Nippon Steel is 1.50-2.0%, and the specified value of B is ≤0.01%.
Mechanical properties
| Mechanical properties at room temperature | ||||
| Standard | Tensile properties (longitudinal) | HardnessHB | ||
| Yield strength(MPa) | Tensile strength(MPa) | Elongation(%) | ||
| SA213 | ≥440 | ≥620 | ≥20 | ≤250 |
| Nippon Steel | ≥440 | ≥590 | ≥20 | ≤250 |
Lasting strength（MPa）of SA213 T92 (NF616) steel tubes
| Standard | 500℃ | 525℃ | 550℃ | 575℃ | 600℃ | 625℃ | 650℃ |
| SA213 | 200 | 165 | 132 | 100 | 72 |
Allowable stress（MPa）of SA213 T92 (NF616) steel tubes
| Temperature℃ | 350℃ | 400℃ | 450℃ | 500℃ | 525℃ | 550℃ | 575℃ | 600℃ | 625℃ | 650℃ |
| Allowable stress | 156.4 | 150.7 | 143.6 | 134.5 | 129.0 | 122.8 | 110.2 | 87.8 | 67.0 | 46.7 |
Note: Interpolated data for ASME code case 2179 values
Antioxidant performance
The steam oxidation resistance tests at 650 and 700 ° C show that the oxidation resistance of SA213 T92 steel tubes at two temperatures is basically the same as that of T91 steel tubes.
Process performance
Heat treatment
The supply status of T92 steel is normalized + tempered. The minimum normalizing temperature specified by ASME code is 1040 ° C + the minimum tempering temperature is 730 ° C.
Welding
SA213 T92 steel has good welding performance. Preheating temperature ≥100 ℃ can suppress welding cracks, indicating that it has excellent crack resistance. Tungsten inert gas shielded welding (TIG), manual arc welding and submerged arc welding can be used. The welding wire is MTS-616 and the electrode MTS-616. The preheating temperature and layer temperature are controlled at 200-350 ℃.