Scenario 1: You Meant SA-213 T91 / T911 (Most Likely)
This is the high-grade alloy tubing used in high-pressure, high-temperature sections of power boilers.
1. Material & Key Characteristics
Standard: ASTM A213 / ASME SA-213 - Standard for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
Grade T91: A chromium-molybdenum alloy steel with vanadium and niobium.
Grade T911: A modified version of T91 with controlled boron and nitrogen for improved creep strength.
Key Feature: Excellent creep strength (resistance to deformation under stress at high temperatures) and oxidation resistance.
2. Chemical Composition (Weight %)
| Element | T91 (%) | T911 (%) |
|---|---|---|
| Carbon (C) | 0.08 - 0.12 | 0.09 - 0.13 |
| Manganese (Mn) | 0.30 - 0.60 | 0.30 - 0.60 |
| Phosphorus (P) | 0.020 max | 0.020 max |
| Sulfur (S) | 0.010 max | 0.010 max |
| Silicon (Si) | 0.20 - 0.50 | 0.10 - 0.50 |
| Chromium (Cr) | 8.00 - 9.50 | 8.50 - 9.50 |
| Molybdenum (Mo) | 0.85 - 1.05 | 0.90 - 1.10 |
| Vanadium (V) | 0.18 - 0.25 | 0.18 - 0.25 |
| Niobium (Nb) | 0.06 - 0.10 | 0.06 - 0.10 |
| Nickel (Ni) | 0.40 max | 0.40 max |
| Aluminum (Al) | 0.04 max | 0.02 max |
| Nitrogen (N) | 0.030 - 0.070 | 0.040 - 0.090 |
| Boron (B) | - | 0.0005 - 0.0050 |
3. Mechanical Properties
Tensile Strength: ≥ 585 MPa (85 ksi)
Yield Strength: ≥ 415 MPa (60 ksi)
Elongation: ≥ 20%
4. Common Applications
Superheater Tubes
Reheater Tubes
High-Temperature Headers and Piping (where specified by code, e.g., SA-335 P91/P911)
Used in advanced coal-fired power plants, waste-to-energy plants, and other high-efficiency boilers where metal temperatures exceed 595°C (1100°F).
Scenario 2: You Meant SA-214 (Carbon Steel Boiler Tube)
This is a more common, low-alloy steel for general boiler and heat exchanger applications.
1. Material & Key Characteristics
Standard: ASTM A214 / ASME SA-214 - Standard for ERW Carbon Steel Boiler and Superheater Tubes.
Grade: The only grade is a Carbon Steel, often referred to as "Grade C" (not to be confused with AISI 1020, etc.).
Key Feature: Electric Resistance Welding (ERW) process makes it cost-effective for medium-pressure services. It is not a seamless tube.
2. Chemical Composition (Weight %)
Carbon (C): 0.06 - 0.18% (Varies by wall thickness)
Manganese (Mn): 0.27 - 0.63% (Varies by wall thickness)
Phosphorus (P): 0.025% max
Sulfur (S): 0.025% max
3. Mechanical Properties
Tensile Strength: ≥ 310 MPa (45 ksi)
Yield Strength: ≥ 172 MPa (25 ksi) - For walls ≤ 0.075 in (1.9 mm), it's 40 ksi min.
Elongation: Varies with wall thickness but is typically ≥ 35%.
4. Common Applications
Boiler Tubes (in lower-temperature sections like the water wall)
Heat Exchanger Tubes
Condenser Tubes
General service where temperatures and pressures are not extreme.
Summary Comparison & Key Differences
| Feature | SA-213 T91 / T911 | SA-214 |
|---|---|---|
| Material Type | Chromium-Molybdenum Alloy Steel | Carbon Steel |
| Manufacturing | Seamless | ERW (Electric Resistance Welded) |
| Key Property | High-Temperature Creep Strength | Good Strength & Formability at Lower Cost |
| Temperature Service | Very High (up to ~650°C / 1200°F) | Moderate |
| Pressure Service | Very High Pressure | Medium Pressure |
| Common Use | Superheaters, Reheaters | Water-wall tubes, Heat exchangers |
| Cost | Higher | Lower |
Conclusion
If your application involves very high temperatures and pressures (like a power plant superheater), you are almost certainly looking for SA-213 T91 or T911.
If your application is for a general industrial boiler or heat exchanger with moderate conditions, you might be looking for the more common SA-214 carbon steel tube.
Always confirm the exact material specification on your project's design documents or data sheets to ensure you select the correct pipe for the intended service conditions.
