ASTM A213 / ASME SA213 T91 Seamless Ferritic Alloy-Steel Boiler Tubes
9Cr-1Mo-V Alloy Steel Tubes for High-Temperature & High-Pressure Service
ASTM A213 / ASME SA213 T91 seamless boiler tubes are advanced ferritic alloy-steel tubes containing 9% chromium and 1% molybdenum, micro-alloyed with vanadium and niobium. Designed for ultra-high temperature and high-pressure service, T91 tubes offer outstanding creep strength, oxidation resistance, and long-term structural stability, making them a preferred material for supercritical and ultra-supercritical boilers.
T91 seamless tubes are widely used in power generation, HRSG boiler tube,refineries, petrochemical plants, and high-temperature heat exchanger systems.
What Is ASTM A213 / ASME SA213?
ASTM A213 ( ASME SA213) is the standard specification for seamless ferritic and austenitic alloy-steel tubes intended for:
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Boilers
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Superheaters
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Reheaters
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Heat exchangers
The standard defines requirements for chemical composition, mechanical properties, heat treatment, manufacturing process, testing, and certification, and is widely used in ASME Boiler & Pressure Vessel Code (BPVC) applications.
Download ASTM A213 standard pdf
Material Grade: T91 (9Cr-1Mo-V-Nb)
T91 is a modified 9Cr-1Mo alloy steel, developed to provide significantly improved performance compared to traditional grades such as T11 and T22.
T91 is A martensitic and ferritic steel alloy used in power plants and boilers. It’s made of chromium-molybdenum steel, and often micro-alloyed with vanadium and niobium. T91 steel is known for its resistance to corrosion and steam oxidation, and its creep rupture strength.
Product Form & Manufacturing
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Product Type: Seamless ferritic alloy-steel tube
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Manufacturing Process: Hot finished / cold drawn
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Delivery Condition: Normalized and tempered (N&T)
Size Range & Specifications
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Outside Diameter: 12.7 mm – 114.3 mm (1/2″ – 4-1/2″)
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Wall Thickness: 2.0 mm – 14.0 mm
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Length: Random length or fixed length
(Custom sizes available upon request)
Chemical Composition – ASTM A213 T91 (Typical, wt %)
| TABLE 1 Chemical Composition | ||||||||||
| Grade | UNS | C | Mn | P | S | Si | Ni | Cr | Mo | Other |
| T91 | K90901 | 0.07–0.14 | 0.30–0.60 | 0.020 | 0.010 | 0.20–0.50 | 0.40 | 8.0–9.5 | 0.85–1.05 | Nb 0.06–0.10 |
Mechanical Properties (Room Temperature)
| TABLE 4 Tensile & Hardness | ||||||
| Grade | UNS | Tensile min | Yield min | Elongation % | Brinell/Vickers | Rockwell |
| T91 | K90901 | 85 [585] | 60 [415] | 20 | 190–250 HBW / 196–265 HV | 90 HRB–25 HRC |
Heat Treatment Requirements
ASTM A213 T91 boiler tubes are supplied in the normalized and tempered condition, ensuring:
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Proper martensitic microstructure
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Maximum creep strength
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Long-term stability in high-temperature service
Post-weld heat treatment (PWHT) is mandatory after welding.
| TABLE 3 Heat Treatment | |||||
| Grade | UNS | Heat Treat Type | Austenitize Temp | Cooling | Temper Temp |
| T91 | K90901 | normalize & temper | 1900–1975 [1040–1080] | — | 1350–1470 [730–800] |
Testing & Inspection
ASTM A213 / ASME SA213 T91 tubes undergo stringent inspection, including:
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Chemical analysis
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Tensile testing
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Hardness testing
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Flattening and bend tests
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Eddy current or hydrostatic testing
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Dimensional & visual inspection
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Certification: EN 10204 3.1 / ASME MTR
T91 vs T22 vs T92 Boiler Tubes
| Grade | Alloy System | Max Service Temp | Typical Use |
|---|---|---|---|
| T22 | 2.25Cr-1Mo | ~580°C | Conventional boilers |
| T91 | 9Cr-1Mo-V | ~610–620°C | Supercritical boilers |
| T92 | 9Cr-0.5Mo-W | ~650°C | USC power plants |
ASTM A213 ASME SA213 T91 seamless tube
ASTM A213 / ASME SA213 T91 seamless ferritic alloy-steel boiler tubes provide superior creep strength, oxidation resistance, and long-term reliability for high-temperature and high-pressure boiler applications. Fully compliant with ASTM and ASME standards, T91 tubes are the preferred solution for modern power plants and advanced thermal systems.
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Download ASTM A213 / ASME SA213 T91 seamless tube specificaiton
