Premium SA213 T9 Seamless Alloy Tube for Superheaters, Reheaters, Boilers, Heat Exchangers, and High-Temperature Industrial Piping
Womic Steel produces high-quality SA213 T9 Seamless Alloy Steel Tube, manufacturing chromium-molybdenum (9Cr-1Mo) ferritic alloy tubes in accordance with ASTM A213 / ASME SA213 specifications. Our SA213 T9 tubes meet the demanding requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, with a minimum tensile strength of 415 MPa and excellent creep resistance at elevated temperatures up to 593°C (1100°F). These seamless alloy tubes are the ideal choice for superheaters, reheaters, high-pressure boilers, heat exchangers, economizers, and high-temperature industrial piping systems requiring superior oxidation resistance and long-term creep strength.
Manufacturer: Womic Steel
1. Product Definition and Scope
SA213 T9 (UNS K90941) is a seamless ferritic alloy steel tube specified under ASTM A213 / ASME SA213 for use in boilers, superheaters, heat exchangers, and other high-temperature pressure-containing equipment. The “T9″ designation indicates a nominal composition of 9% chromium and 1% molybdenum, which provides excellent high-temperature strength, oxidation resistance, and creep resistance. T9 is widely used in power generation, petrochemical processing, and marine boiler applications where operating temperatures exceed the capability of lower alloy grades such as T11 and T22.
Manufacturing Process: T9 tubes shall be manufactured by the seamless process and shall be either hot-finished or cold-finished, as specified. Hot-finished tubes are produced by hot rolling or extrusion; cold-finished tubes are cold drawn from hot-finished hollows, offering higher dimensional accuracy and smoother surface finish. T9 is typically supplied in the annealed condition (full or isothermal anneal, or normalize and temper).
Grade Designation:
| Designation | Meaning |
| SA213 | ASME specification for seamless ferritic and austenitic alloy-steel tubes for boilers, superheaters, and heat exchangers |
| T9 | Grade designation: 9% Chromium – 1% Molybdenum ferritic alloy |
| UNS K90941 | Unified numbering system designation for T9 |
Equivalent Standards and Grades:
| Standard | Equivalent Grade |
| ASTM A213 / ASME SA213 | T9 |
| ASTM A335 | P9 (pipe form) |
| EN 10216-2 | X11CrMo9-1 (1.7386) |
| DIN 17175 | X12CrMo9-1 |
| JIS G3462 | STBA 26 |
| BS 3059 | 622-490 |
| ISO 2604 II | S38 |
Manufacturer: Womic Steel
2. Chemical Composition Requirements
The chemical composition of SA213 T9 is precisely controlled to achieve the desired high-temperature strength, creep resistance, and oxidation resistance. The 9% chromium content provides excellent oxidation and corrosion resistance at elevated temperatures, while the 1% molybdenum content enhances creep strength and high-temperature stability.
SA213 T9 Chemical Composition (Heat Analysis – Seamless Tube):
| Element | Composition (%) – Minimum | Composition (%) – Maximum |
| Carbon (C) | — | 0.15 |
| Manganese (Mn) | 0.30 | 0.60 |
| Phosphorus (P) | — | 0.025 |
| Sulfur (S) | — | 0.025 |
| Silicon (Si) | 0.25 | 1.00 |
| Chromium (Cr) | 8.00 | 10.00 |
| Molybdenum (Mo) | 0.90 | 1.10 |
| Vanadium (V) | — | 0.25 (optional, typical 0.18-0.25) |
Composition Notes:
| Element | Engineering Note |
| Chromium (8.00-10.00%) | Forms protective oxide layer; slows oxide growth; improves hot tensile strength |
| Molybdenum (0.90-1.10%) | Stabilizes carbides; delays grain-boundary sliding; enhances creep resistance |
| Silicon (0.25-1.00%) | Deoxidation; solid-solution contribution |
| Carbon (≤0.15%) | Strength-ductility balance for bends and coils |
| Vanadium (optional) | Microalloying for additional creep strength |
The golden ratio composition of “9% chromium + 1% molybdenum” ensures stable mechanical properties even at high temperatures of 593℃, making T9 an essential material for high-pressure applications such as supercritical power plants and marine boilers.
3. Mechanical Properties
The mechanical properties of SA213 T9 seamless tubes are specified to ensure reliable performance under high-temperature and high-pressure operating conditions. T9 delivers higher hot strength and steadier scale behavior than 1.25–2.25Cr grades without the fabrication sensitivity of 9Cr–V–Nb steels, making it a practical choice where long hours, thermal gradients and coil integrity dominate risk.
Tensile Requirements (Room Temperature):
| Property | Minimum | Typical | Unit |
| Tensile Strength | 415 MPa (60 ksi) | 450-550 MPa | — |
| Yield Strength (0.2% offset) | 205 MPa (30 ksi) | 280-350 MPa | — |
| Elongation in 2 in. or 50 mm | 30% | 35-40% | — |
Elongation Adjustment for Thin Walls:
| Wall Thickness | Minimum Elongation |
| 5/16 in. (8.0 mm) and over | 30% |
| 1/4 in. (6.4 mm) | 27% |
| 3/16 in. (4.8 mm) | 24% |
| 1/8 in. (3.2 mm) | 21% |
| 1/16 in. (1.6 mm) | 18% |
| 0.035 – 0.022 in. (0.9 – 0.6 mm) | 17% |
| 0.022 – 0.015 in. (0.6 – 0.4 mm) | 16% |
When the wall thickness is between the values above, the minimum elongation shall be determined by the formula: E = 48t + 15.00 (in.) or E = 1.87t + 15.00 (mm).
Hardness Requirements:
| Property | Maximum |
| Brinell Hardness (HBW) | 179 |
| Rockwell Hardness (HRB) | 89 |
High-Temperature Tensile Properties (Reference Values):
| Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) |
| 20 | 450-550 | 280-350 |
| 300 | 400-480 | 220-280 |
| 400 | 380-450 | 200-250 |
| 500 | 350-420 | 180-230 |
| 593 | 250-320 | 140-180 |
Creep Rupture Strength (Typical Values):
| Temperature (°C) | 100,000 Hour Stress (MPa) |
| 550 | 60-80 |
| 593 | 35-45 |
| 650 | 15-25 |
T9′s creep advantage sits in the long-life region: a fine, continuous grain-boundary carbide network from proper tempering improves rupture time and keeps deformation uniform.
4. Heat Treatment Requirements
T9 steel tubes shall be reheated for heat treatment according to the following methods, and the heat treatment shall be carried out separately and in addition to heating for hot forming.
Heat Treatment Requirements:
| Grade | Heat Treat Type | Subcritical Annealing or Tempering Temperature (min) |
| T9 (K50400) | Full or isothermal anneal; normalize and temper | 1250°F (675°C) min |
Heat Treatment Process Details:
| Condition | Process | Temperature Range | Application |
| Normalizing | Heating followed by air cooling | 925-980°C (1700-1800°F) | Refine grain structure |
| Tempering | Reheating after normalizing | 675-760°C (1250-1400°F) | Develop final mechanical properties |
| Full Annealing | Slow cooling from austenitizing temperature | 870-900°C (1600-1650°F) | Softest condition for forming |
Normalizing (heated to 925–980°C) followed by tempering (675–760°C) refines the microstructure, balancing tensile strength (≥415 MPa) and ductility (elongation ≥30%).
Manufacturer: Womic Steel performs heat treatment in accordance with ASTM A213 / ASME SA213 requirements. Heat treatment certificates are provided upon request.
5. Dimensional Tolerances
Outside Diameter Tolerances – Hot Finished:
| OD Range (mm) | Tolerance (mm) |
| OD ≤ 101.6 | +0.4 / -0.8 |
| 101.6 < OD ≤ 190.5 | +0.4 / -1.2 |
| 190.5 < OD ≤ 228.6 | +0.4 / -1.6 |
Outside Diameter Tolerances – Cold Drawn:
| OD Range (mm) | Tolerance (mm) |
| OD < 25.4 | ±0.10 |
| 25.4 ≤ OD ≤ 38.1 | ±0.15 |
| 38.1 < OD < 50.8 | ±0.20 |
| 50.8 ≤ OD < 63.5 | ±0.25 |
| 63.5 ≤ OD < 76.2 | ±0.30 |
| 76.2 ≤ OD ≤ 101.6 | ±0.38 |
| 101.6 < OD ≤ 190.5 | +0.38 / -0.64 |
| 190.5 < OD ≤ 228.6 | +0.38 / -1.14 |
Wall Thickness Tolerances – Hot Finished:
| OD Range | WT Range | Tolerance (%) |
| OD ≤ 101.6 | WT ≤ 2.4 | +40 / -0 |
| OD ≤ 101.6 | 2.4 < WT ≤ 3.8 | +35 / -0 |
| OD ≤ 101.6 | 3.8 < WT ≤ 4.6 | +33 / -0 |
| OD ≤ 101.6 | WT > 4.6 | +28 / -0 |
Ovality Tolerances:
| Condition | Permitted Ovality |
| At tube ends | 1.0% of nominal OD |
| At other locations | 1.5% of nominal OD |
Length Tolerances:
| Length Type | Tolerance |
| Random Length (RL) | 5 – 12 meters |
| Specific Length (≤ 6m) | +50 mm / -0 |
| Specific Length (6-12m) | +100 mm / -0 |
6. Available Sizes and Specifications
T9 Seamless Tube Size Range:
| Parameter | Hot Finished | Cold Finished |
| OD Range (mm) | 12.7 – 219.1 | 6.35 – 101.60 |
| OD Range (inches) | 1/2″ – 8″ | 1/4″ – 4″ |
| WT Range (mm) | 0.9 – 15.0 | 0.5 – 12.7 |
| WT Range (inches) | 0.035 – 0.591 | 0.020 – 0.500 |
| Standard Length (m) | 6 – 12 | 6 – 12 |
Common T9 Tube Sizes (OD x WT):
| OD (mm) | WT 2.0 | WT 2.5 | WT 3.0 | WT 3.5 | WT 4.0 | WT 5.0 | WT 6.0 |
| 12.7 | ✓ | ✓ | ✓ | — | — | — | — |
| 15.88 | ✓ | ✓ | ✓ | ✓ | — | — | — |
| 19.05 | ✓ | ✓ | ✓ | ✓ | ✓ | — | — |
| 25.4 | — | ✓ | ✓ | ✓ | ✓ | ✓ | — |
| 31.8 | — | — | ✓ | ✓ | ✓ | ✓ | ✓ |
| 38.1 | — | — | ✓ | ✓ | ✓ | ✓ | ✓ |
| 44.5 | — | — | — | ✓ | ✓ | ✓ | ✓ |
| 50.8 | — | — | — | — | ✓ | ✓ | ✓ |
| 60.3 | — | — | — | — | — | ✓ | ✓ |
| 63.5 | — | — | — | — | — | ✓ | ✓ |
| 76.2 | — | — | — | — | — | — | ✓ |
| 88.9 | — | — | — | — | — | — | ✓ |
| 101.6 | — | — | — | — | — | — | ✓ |
| 114.3 | — | — | — | — | — | — | ✓ |
| 127.0 | — | — | — | — | — | — | ✓ |
| 141.3 | — | — | — | — | — | — | ✓ |
| 159.0 | — | — | — | — | — | — | ✓ |
| 168.3 | — | — | — | — | — | — | ✓ |
| 177.8 | — | — | — | — | — | — | ✓ |
| 219.1 | — | — | — | — | — | — | ✓ |
U-Bend Tubes: Womic Steel can supply SA213 T9 tubes in U-bend configuration. Post-bending, U-bend tubes often require stress-relief heat treatment (650–700°C) to mitigate residual stresses induced during forming, ensuring compliance with the standard’s mechanical property requirements.
Manufacturer: Womic Steel maintains extensive inventory of SA213 T9 seamless tubes in common sizes for immediate dispatch.
7. Inspection and Testing Requirements
| Test / Inspection | Requirement | Method | Acceptance Criteria | Frequency |
| Chemical Analysis | Required | Spectrometer | Per ASTM A213 | Per heat |
| Tensile Test | Required | ASTM A370 | ≥415 MPa / ≥205 MPa | Per heat |
| Hardness Test | Required | ASTM E10/E18 | ≤179 HBW / ≤89 HRB | Per heat |
| Flattening Test | Required | ASTM A213 | No cracks | Per lot |
| Flaring Test | Required | ASTM A213 | No cracks | Per lot |
| Hydrostatic Test or NDT | Required (100%) | ASTM A213 | No leakage or no flaws | Each tube |
Non-Destructive Testing (NDT) Options:
| Test Method | Application | Coverage | Standard |
| Eddy Current Test (ECT) | Surface and near-surface flaw detection | 100% of tube surface | ASTM E309 |
| Ultrasonic Test (UT) | Internal flaw detection | 100% of tube length | ASTM E213 |
| Hydrostatic Test | Pressure integrity verification | 100% of tubes | ASTM A1016 |
Hydrostatic Test Pressure:
● Test Pressure Formula: P = 2St/D
● Allowable Stress (S): Based on material strength at test temperature
● Hold Time: 5 seconds minimum
● Test Record: Required for each tube per ASTM A1016
Flattening Test Requirement: One flattening test shall be made on specimens from each end of one finished tube, not the one used for the flaring test, from each lot. The tube shall be flattened to a specified distance without cracking.
Flaring Test Requirement: One flaring test shall be made on specimens from each end of one finished tube, not the one used for the flattening test, from each lot.
8. Heat Treatment Verification
Heat treatment is critical for T9 material to achieve the proper microstructure and mechanical properties.
Required Heat Treatment Verification Records (Available upon request):
| Record Type | Information Provided |
| Heat Treatment Certificate | Time-temperature charts, furnace records, quench media |
| Normalizing Record | Temperature, hold time, cooling method |
| Tempering Record | Temperature, hold time, cooling method |
| Microstructure Examination | Verification of fine, continuous grain-boundary carbide network |
| Hardness Verification | Confirmation of ≤179 HBW after heat treatment |
9. Applications
SA213 T9 seamless tubes are specifically designed for high-temperature, high-pressure service applications where long-term creep strength and oxidation resistance are critical.
| Industry | Application |
| Power Generation | Superheater tubes, reheater tubes, boiler water wall tubes, economizer tubes, header tubes for subcritical and supercritical power plants |
| Combined Cycle Power Plants | Heat Recovery Steam Generator (HRSG) superheater and reheater sections |
| Petrochemical | Hydrogenation reactor piping, high-temperature cracking furnace tubes, reformer tube manifolds, process heater coils |
| Marine Power | High-pressure boilers for LNG carriers, steam systems for ocean-going vessels (DNV certification available) |
| Refining | Catalytic reformer piping, high-temperature heat exchanger tubes, furnace tubes |
| Industrial Heating | Radiant tube heaters, convection section coils, process heaters |
T9 is designed for hotter superheater/reheater sections and headers where long-term creep strength dominates. With ~9% Cr, oxidation tends to follow a parabolic law; the parabolic rate is much lower than in low-Cr steels, which limits scale thickness and spallation events.
10. Comparison with Other Alloy Grades
| Grade | Nominal Composition | Tensile (MPa) | Yield (MPa) | Max Service Temp | Typical Application |
| T11 | 1.25Cr-0.5Mo | ≥415 | ≥205 | 540°C | Moderate-temp boilers |
| T22 | 2.25Cr-1Mo | ≥415 | ≥205 | 565°C | Hotter banks, cost-efficient |
| T9 | 9Cr-1Mo | ≥415 | ≥205 | 593°C | High-temp service |
| T91 | 9Cr-1Mo-V-Nb | ≥585 | ≥415 | 650°C | Very hot superheater sections |
T9 delivers higher hot strength and steadier scale behavior than 1.25–2.25Cr grades without the fabrication sensitivity of 9Cr–V–Nb steels, making it a practical choice where long hours, thermal gradients and coil integrity dominate risk.
11. Pipe/Tube Connection Methods
| Connection Type | Description | Typical Use |
| Buttweld (BW) | Beveled ends for butt welding | High-temperature boiler tube connections |
| Socket Weld (SW) | Socket for fillet weld | Small diameter connections |
| Flanged | RF or RTJ facing | Easy disassembly for maintenance |
| U-Bend | Bent tubes for heat exchangers | Accommodate thermal expansion |
12. Corrosion Protection (External Coating – Optional)
| Coating | Thickness | Standard | Application |
| Black Varnish | 15-25 microns | Shop primer | Temporary protection during storage and transport |
| Rust Preventive Oil | Light film | — | Short-term protection |
13. Welding Procedure for SA213 T9
SA213 T9 has high hardenability due to its 9% chromium content and is susceptible to cold cracking if proper welding procedures are not followed.
Recommended Welding Processes:
| Process | Application |
| GTAW (TIG) | Preferred method; lowest hydrogen content; suitable for root pass |
| SMAW (Stick) | Field welding; use low-hydrogen electrodes |
Recommended Filler Metals:
| Filler Metal | AWS Classification | Application |
| ER90S-B3 | AWS A5.28 | GTAW root pass |
| E9018-B3 | AWS A5.5 | SMAW fill and cap passes |
| ER80S-B2L | AWS A5.28 | Alternative for lower strength requirements |
Critical Welding Requirements:
| Parameter | Requirement |
| Preheating Temperature | 150-250°C (300-480°F) – mandatory for all thicknesses |
| Maximum Interpass Temperature | 300°C (572°F) |
| Post-Weld Heat Treatment (PWHT) | 675-760°C (1250-1400°F) – mandatory |
| PWHT Hold Time | Minimum 1 hour per 25mm thickness |
| Welding Consumables | Low hydrogen type (H8 or lower) |
| Shielding Gas | 100% Argon for GTAW |
T9 alloy has high hardenability. Preheat is mandatory (typically 150-250°C). PWHT is also mandatory, typically tempering around 675-760°C (1250-1400°F) after welding. The high chromium content requires careful heat input control to avoid cracking and maintain proper mechanical properties. After welding, the entire weld joint must be heat treated to restore the tempered martensitic structure. Hydrogen control is critical; low-hydrogen practices must be strictly followed to prevent hydrogen-induced cracking. PWHT at 675-760°C (1250-1400°F) is required to temper the martensitic structure and relieve residual stresses.
14. Traceability and Marking
Each tube shall be marked with the following information (per ASTM A1016):
| Marking Element | Example |
| Manufacturer Name | Womic Steel |
| Specification | ASTM A213 / ASME SA213 |
| Grade | T9 |
| UNS Number | K90941 |
| Size | OD x WT |
| Heat Number | H12345 |
| Length | 6.0m |
| Hydrostatic Test | Hydro / ECT |
Marking Example:
| Line | Content |
| Line 1 | Womic Steel ASTM A213/ASME SA213 T9 |
| Line 2 | 38.1mm x 3.0mm x 6.0m |
| Line 3 | Heat No: H12345 |
| Line 4 | UNS K90941 / ECT |
15. Packaging
| Size | Method |
| Small diameter (≤ 1/2″) | Bundled with steel straps, carton boxes |
| Medium diameter (1/2″ – 2″) | Hexagonal bundles, plastic end caps |
| Large diameter (≥ 2″) | Single or bundled with fabric wrapping, plastic end caps |
16. Quality Documents
| Document | Standard | Included |
| Mill Test Report (MTR) | EN 10204 Type 3.1 | Yes |
| Heat Treatment Certificate | ASTM A213 | Yes |
| Hydrostatic Test Report | ASTM A1016 | Yes |
| NDT Report (UT/ECT) | ASTM E213/E309 | Upon request |
| Dimensional Inspection Report | ASTM A213 | Yes |
| Certificate of Origin | Chamber of Commerce | Yes |
| Third-Party Inspection | SGS, BV, DNV, TUV, LR, ABS | Optional |
17. Contact Information
Website: www.womicsteel.com
E-mail: sales@womicsteel.com
Tel / WhatsApp / WeChat:
Victor: +86 15575100681
Jack: +86 18390957568
Womic Steel – Your reliable partner for SA213 T9 seamless alloy tubes, stainless steel products, and custom solutions for boiler, superheater, heat exchanger, and power generation applications.
Post time: Sep-30-2026