ASTM A213 T9 Alloy Steel Seamless U Bend Tube Boiler Tube High Temperature Resistance
ASTM A213 is a standard specifically for the core material of seamless steel tubes used in heat exchange equipment operating under high pressure and high temperature conditions.
Tubes manufactured according to this standard are widely used in boilers, superheaters, reheaters, heat exchangers, condensers, and other equipment.
ASTM A213 T9 SMLS Tube belongs to the T-series materials, primarily composed of low-alloy chromium-molybdenum steel, and is characterized by its high-temperature resistance. T9 is a ferritic alloy steel with a composition of 9Cr-1Mo-Si.
The average and minimum wall thicknesses of tubes under this standard are acceptable, so specific definitions are necessary.
| Chemical Composition (%) | ||
| Element | Standard Requirement (≤) | Typical Value / Note |
| Carbon (C) | 0.15 max | 0.09–0.13 |
| Manganese (Mn) | 0.30–0.60 | 0.40–0.60 |
| Phosphorus (P) | 0.025 max | 0.020 max |
| Sulfur (S) | 0.025 max | 0.015 max |
| Silicon (Si) | 0.25–1.00 | 0.50–0.80 |
| Chromium (Cr) | 8.00–10.00 | 8.50–9.50 |
| Molybdenum (Mo) | 0.90–1.10 | 0.95–1.05 |
| Iron (Fe) | Balance | Balance |
| Others | — | Residuals |
| Mechanical Properties | ||
| Property | Standard Requirement | Note / Condition |
| Tensile Strength, min | 415 MPa (60 ksi) | |
| Yield Strength, min | 205 MPa (30 ksi) | 0.2% offset |
| Elongation in 2 in (50 mm), min | 30% | For wall thickness ≥ 0.007 in (0.18 mm) |
| Hardness, max | 179 HBW | Brinell Hardness (typical) |
| Heat Treatment | Full Anneal | Or normalized and tempered |
Applications and Advantages of T9 Material:
T22 is the most economical mainstream choice below approximately 580°C.
T9 offers high cost-effectiveness and can replace T22 in high-temperature applications, especially in the 565°C to 595°C range, where its resistance to steam oxidation is a core advantage.
When the temperature consistently exceeds approximately 595°C, or the pressure is higher, more advanced alloys such as T91/T92 should be selected to take advantage of their significantly higher creep strength.
When the temperature consistently exceeds approximately 650°C, austenitic stainless steel should generally be considered.
1. Low-temperature/terminal superheaters and reheaters in high-pressure power plant boilers
2. Boilers in petrochemical heating furnaces
3. Heat exchangers (shell side/tube side with corrosive media)
4. Upgrading and replacing T22 tube sections in old units
