ASME SA213 T9 Seamless U-Tube for High-Temperature Heat Exchanger Service
Company & Product Positioning
Yuhong Group Co., Ltd. specializes in heat exchanger tube solutions with particular technical authority in U-bend tube forming and heat treatment for high-temperature shell-and-tube heat exchanger service. All products are manufactured and documented in full compliance with ASME Section II and ASTM specifications.
Chemical Composition (ASME SA-213 / ASTM A213 Table 1)
| Element |
Composition (%) |
Requirement |
| Carbon (C) |
≤ 0.15 |
Max |
| Manganese (Mn) |
0.30 - 0.60 |
Range |
| Phosphorus (P) |
≤ 0.025 |
Max |
| Sulfur (S) |
≤ 0.025 |
Max |
| Silicon (Si) |
0.25 - 1.00 |
Range |
| Chromium (Cr) |
8.00 - 10.00 |
Range |
| Molybdenum (Mo) |
0.90 - 1.10 |
Range |
Reference: ASME SA-213/SA-213M Table 1 (Low Alloy Steels - Grade T9, UNS K90941)
The 9% chromium content provides oxidation resistance through formation of a protective chromium oxide layer; the 1% molybdenum contributes creep strength at elevated temperatures.
Mechanical Properties & Heat Treatment
Tensile and Hardness Requirements (ASME SA-213 Table 4)
| Property |
Requirement |
| Tensile Strength, min |
415 MPa (60 ksi) |
| Yield Strength, min |
205 MPa (30 ksi) |
| Elongation (in 2 in. or 50 mm), min |
30% |
| Hardness, max |
179 HBW / 190 HV |
| Rockwell, max |
89 HRB |
Reference: ASME SA-213/SA-213M Table 4
Heat Treatment (ASME SA-213 Table 3)
| Grade |
UNS Number |
Heat Treat Type |
Tempering Temperature |
| T9 |
K90941 |
Full or isothermal anneal; or normalize and temper |
1250°F [675°C] min |
Reference: ASME SA-213/SA-213M Table 3
Heat treatment shall be carried out separately and in addition to heating for hot forming. For ferritic alloy steels including T9, the tubes shall be reheated for heat treatment in accordance with Table 3 requirements.
Manufacturing & Testing Requirements
Manufacturing Process
Tubes shall be made by the seamless process and shall be either hot finished or cold finished, as specified.
Required Tests per ASME SA-213
Each lot shall be subject to the following inspections:
| Test |
Frequency |
| Tension test |
One specimen from one tube per lot (≤50 tubes); two tubes per lot (>50 tubes) |
| Hardness test (Brinell/Vickers/Rockwell) |
Two tubes per lot |
| Flattening test |
Each end of one finished tube per lot |
| Flaring test |
Each end of one finished tube per lot (different tube from flattening test) |
| Hydrostatic or Nondestructive Electric Test |
Each tube |
Reference: ASME SA-213/SA-213M Sections 9 and 10
Special Consideration: Certain ferritic steels covered by this specification will harden if cooled rapidly from above their critical temperature. Chromium-containing steels with 4% and higher chromium—including T9 with 8-10% Cr—may air harden when cooled in air from high temperatures. Operations involving heating above critical temperatures (welding, flanging, hot bending) should be followed by suitable heat treatment.
Supporting Fabrication Capabilities
Yuhong Group provides integrated supply for heat exchanger fabrication:
| Component |
Material Compatibility |
| U-bend tubes |
ASTM A213 T9 (and other T-grades) |
| Straight tubes |
ASTM A213 / A269 / A249 |
| Tubesheets |
SA-516 Gr.70, SA-266, clad materials |
| Baffles |
Carbon steel, stainless steel |
| Shells & channels |
SA-516 Gr.70, SA-240 |
Minimum U-bend radius: 1.5 * OD (standard), with tighter radii available upon agreement.
Application Range
ASME SA-213 T9 seamless tubes are specified for high-temperature, high-pressure services including:
- Superheaters and reheaters in power plant boilers
- Shell-and-tube heat exchangers in refineries and petrochemical plants
- Heat exchanger tube bundles for high-temperature process services
- Air-cooled heat exchanger tube sections
- Fired heater convection sections and cracking furnace tubes
Operating envelope: Sustained service at temperatures up to approximately 600-650°C (1110-1200°F) with oxidation resistance and creep strength maintained.
Technical Highlights & Customization
Oxidation Resistance: The 8-10% chromium content forms a stable protective oxide scale, providing superior resistance to scaling in high-temperature oxidizing and steam environments compared to lower-alloy grades.
Creep Strength: The 0.90-1.10% molybdenum addition provides enhanced elevated-temperature strength and creep resistance essential for long-term service in superheater and reheater applications.
Customization Available:
- Outside diameter: 6.35mm to 219.1mm (or as specified)
- Wall thickness: 0.8mm to 15mm (minimum or average wall as ordered)
- Length: Specific or random lengths up to 12m+
- U-bend radii: Standard 1.5*OD; custom radii available
- Surface finish: As-rolled, pickled, or bright annealed
- End preparation: Plain, beveled, or threaded
FAQ - Technical Considerations for T9 U-Tube Selection
Q: Why choose T9 over T22 or T11 for superheater service?
T9 offers higher oxidation resistance and creep strength at elevated temperatures due to its 9% chromium and 1% molybdenum content, making it suitable for hotter superheater and reheater sections where lower-alloy grades may experience accelerated scaling.
Q: What heat treatment is required for ASME SA-213 T9 tubes?
T9 tubes shall be normalized and tempered, or full or isothermal annealed, with a minimum tempering temperature of 1250°F [675°C]. Heat treatment must be performed separately from hot forming.
Q: What testing is mandatory for T9 U-tubes?
Each tube requires either hydrostatic or nondestructive electric testing. Per lot, tension, hardness, flattening, and flaring tests are required from designated tubes.
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