SA213 T91 Tubes – ASME SA213 / ASTM A213 T91 Alloy Steel Seamless Boiler Tubes (UNS K90901)
ASC LLP, Mumbai, supplies SA213 T91 tubes. These are ASME SA213 / ASTM A213 Grade T91 seamless 9Cr-1Mo-V alloy steel tubes for boiler superheaters, reheaters and heat-recovery steam generators. They come normalised and tempered, Type 1 or Type 2, with EN 10204 3.1 certificates. See all our boiler tubes.
What is T91 Material?
T91 is a 9% chromium, 1% molybdenum steel with controlled additions of vanadium, niobium and nitrogen. It belongs to the family known as creep-strength-enhanced ferritic (CSEF) steels. Fine vanadium and niobium carbonitrides give T91 roughly twice the creep strength of T22 at 550 – 600 °C. Its 9% chromium also gives good steam-side oxidation resistance. Its strength depends on correct heat treatment: normalising, then tempering, and post-weld heat treatment after every weld.
ASTM A213 covers seamless ferritic and austenitic alloy steel boiler, superheater and heat-exchanger tubes, from about 3.2 mm ID up to 5″ (127 mm) OD and 0.4 – 12.7 mm wall. ASME SA213 is the identical Boiler & Pressure Vessel Code version. The same material as pipe is A335 P91.
T91 Type 1 vs Type 2
Current editions of A213 list T91 as Type 1 and Type 2. Both have the same mechanical properties and heat treatment. Type 2 has tighter chemistry: lower limits on residual and tramp elements (such as aluminium, arsenic, tin, antimony and boron) and a minimum nitrogen-to-aluminium ratio, for more consistent long-term creep strength. Many utilities and boiler makers now specify Type 2, so please state the type on your enquiry.
Welding & PWHT of T91 Tubes
- Use a qualified procedure with matching 9Cr-1Mo-V-Nb filler; preheat is typically about 200 – 250 °C.
- Allow the weld to transform before post-weld heat treatment.
- Post-weld heat treatment, typically around 745 – 775 °C, is required, with hardness checks afterwards.
- Over-tempering, or skipping PWHT, reduces creep life.
Read more: welding considerations for T91 tubes.
Applications of SA213 T91 Tubes
- Utility boilers: final superheater and reheater tubes, superheater outlet sections
- HRSGs: high-pressure superheater and reheater tubes in combined-cycle plants
- Industrial boilers: high-temperature superheater coils
- Headers and links: small-diameter header nipples and connecting tubes
SA213 T91 Tube Size & Weight Chart (Typical Superheater Sizes)
| OD (mm) | Wall (mm) | ID (mm) | Weight (kg/m) |
| 31.8 | 3.6 | 24.6 | 2.48 |
| 38.1 | 4.0 | 30.1 | 3.33 |
| 38.1 | 5.0 | 28.1 | 4.04 |
| 44.5 | 5.0 | 34.5 | 4.82 |
| 50.8 | 5.6 | 39.6 | 6.18 |
| 50.8 | 7.1 | 36.6 | 7.57 |
| 57.0 | 6.3 | 44.4 | 7.80 |
| 63.5 | 8.0 | 47.5 | 10.84 |
A213 tubes are ordered by OD × average or minimum wall (not pipe schedule). Any size within about 3.2 mm ID to 127 mm OD and 0.4 – 12.7 mm wall can be supplied. Weights calculated for T91 density (7.77 g/cm³).
Mechanical Properties of SA213 T91 Tubes
| Property | ASME SA213 T91 (Type 1 & 2) |
| Tensile strength, min. | 585 MPa (85 ksi) |
| Yield strength, min. | 415 MPa (60 ksi) |
| Elongation in 50 mm, min. | 20% |
| Hardness | 190 – 250 HBW (196 – 265 HV; 90 HRB – 25 HRC) |
Hardness below 190 HBW usually indicates over-tempering and loss of creep strength.
SA213 T91 Tube Specifications
| Item | Details |
| Specification | ASTM A213 / ASME SA213, Grade T91 (Type 1 or Type 2) |
| UNS | K90901 |
| Type | Seamless, hot finished or cold drawn |
| Size | About 3.2 mm ID to 127 mm (5″) OD; wall 0.4 – 12.7 mm |
| Heat treatment | Normalise 1040 – 1080 °C + temper 730 – 800 °C |
| Length | Fixed lengths to drawing; U-bends and coils on request |
| Testing | Tension, flattening, flaring, hardness, hydro or NDE (eddy current / UT), PMI |
| Certificate | EN 10204 3.1; IBR / third-party inspection on request |
T91 Material Composition (SA213 T91)
| Element | SA213 T91 Type 1 (%) |
| Carbon (C) | 0.07 – 0.14 |
| Manganese (Mn) | 0.30 – 0.60 |
| Phosphorus (P) | 0.020 max. |
| Sulphur (S) | 0.010 max. |
| Silicon (Si) | 0.20 – 0.50 |
| Chromium (Cr) | 8.00 – 9.50 |
| Molybdenum (Mo) | 0.85 – 1.05 |
| Vanadium (V) | 0.18 – 0.25 |
| Niobium (Nb) | 0.06 – 0.10 |
| Nitrogen (N) | 0.030 – 0.070 |
| Nickel (Ni) | 0.40 max. |
| Aluminium (Al) | 0.02 max. |
| Titanium (Ti) | 0.01 max. |
| Zirconium (Zr) | 0.01 max. |
Type 2 has tighter limits on residual elements and a minimum N/Al ratio – check the current ASTM A213 for the full Type 2 table.
Physical Properties of T91
| Property | Value (approx., at 20 °C) |
| Density | 7.77 g/cm³ |
| Modulus of elasticity | ≈ 218 GPa |
| Thermal conductivity | ≈ 26 W/m·K |
| Magnetic | Yes (ferritic / martensitic) |
T91 Equivalent Grades
| Standard | Equivalent / related grade |
| ASTM / ASME | A213 / SA213 T91 (K90901) |
| EN 10216-2 | X10CrMoVNb9-1 (1.4903) |
| Pipe | ASTM A335 P91 |
| Fittings / forgings | A234 WP91, A182 F91 |
SA213 T91 vs T11, T22, T92 & TP347H
| Grade | Nominal composition | Tensile / yield min. (MPa) | Typical use |
| T11 | 1¼Cr-½Mo | 415 / 205 | Lower-temperature superheater sections |
| T22 | 2¼Cr-1Mo | 415 / 205 | Superheater and reheater tubes |
| T91 | 9Cr-1Mo-V-Nb | 585 / 415 | High-temperature superheaters and reheaters |
| T92 | 9Cr-0.5Mo-1.8W-V-Nb | 620 / 440 | Ultra-supercritical boilers |
| TP347H | 18Cr-10Ni-Nb (austenitic) | 515 / 205 | Hottest superheater sections |
Matching T91 / P91 Products
Why Buy SA213 T91 Tubes from ASC LLP?
- Correct paperwork: SA213 T91 Type 1 or Type 2 with 3.1 certificates showing heat treatment, hardness and full chemistry, including Nb and N.
- Checks before dispatch: PMI and hardness verification; IBR and third-party inspection on request.
- Exact lengths and bends to boiler drawings.
- Export packing with end caps, in bundles or wooden boxes.
Buying guide: what to check before buying A213 T91 tubes. Send OD, wall, type, length and quantity to sales@amardeepsteel.com, call 022-67439130 or contact us.
Frequently Asked Questions – SA213 T91 Tubes
What is T91 material?
T91 is a 9% chromium, 1% molybdenum alloy steel with vanadium, niobium and nitrogen (UNS K90901), supplied as seamless tube to ASTM A213 / ASME SA213. It is a creep-strength-enhanced ferritic steel used for high-temperature superheater and reheater tubes.
What is the chemical composition of SA213 T91?
SA213 T91 Type 1 contains C 0.07–0.14%, Mn 0.30–0.60%, Si 0.20–0.50%, Cr 8.00–9.50%, Mo 0.85–1.05%, V 0.18–0.25%, Nb 0.06–0.10% and N 0.030–0.070%, with P 0.020% max., S 0.010% max. and Ni 0.40% max.
What are the mechanical properties of SA213 T91 tubes?
Minimum tensile strength is 585 MPa (85 ksi), minimum yield strength 415 MPa (60 ksi), minimum elongation 20%, and hardness 190–250 HBW.
What is the heat treatment for T91 tubes?
SA213 T91 tubes are normalised at 1040–1080 °C and tempered at 730–800 °C. Post-weld heat treatment is required after welding.
What is the difference between T91 and P91?
T91 and P91 are the same 9Cr-1Mo-V material. T91 is seamless tube to ASTM A213 (up to 5″ OD, ordered by OD × wall), while P91 is seamless pipe to ASTM A335 (NPS sizes with pipe schedules).
What is the difference between T91 and T22?
T22 is a 2¼Cr-1Mo steel with 415 MPa tensile strength. T91 is a 9Cr-1Mo-V-Nb steel with 585 MPa tensile strength and much higher creep strength, so it is used for hotter superheater and reheater sections.
Global Reach
ASC LLP supplies alloy steel boiler tubes, pipes and fittings to boiler makers, power plants and EPC contractors in the USA, Europe, the Middle East and Asia, with secure packing and full documentation. Buyers worldwide rely on our SA213 T91 tubes for certified material and traceability.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
