ASTM A213/A213M Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
ASTM A213 is a comprehensive specification covering seamless (SMLS) tubes made from ferritic and austenitic alloy steels. It is a crucial standard for high-temperature and high-pressure service in critical applications like boilers, superheaters, heat exchangers, and condensers in the power and petrochemical industries.
Key Features:
Material: Alloy Steel (including both ferritic and austenitic stainless steels).
Manufacturing Process: Seamless (SMLS).
Primary Use: Boiler tubes, superheaters, heat exchangers, and condenser tubes for elevated temperature and corrosive service.
Key Property: Specified grades offer enhanced creep strength, oxidation resistance, and corrosion resistance compared to plain carbon steels like A192 or A210.
Common Alloy Steel Grades (Examples):
A213 includes many grades. Common ones for "CS" or low-alloy applications include:
| Grade | Type | Key Alloying Elements | Typical Use Case |
|---|---|---|---|
| T5 | Ferritic | 5% Chromium (Cr), 0.5% Molybdenum (Mo) | Moderate oxidation resistance & strength. |
| T9 | Ferritic | 9% Chromium (Cr), 1% Molybdenum (Mo) | Higher oxidation resistance than T5. |
| T11 | Ferritic | 1.25% Chromium (Cr), 0.5% Molybdenum (Mo) | Common for boiler tubes and superheaters. |
| T22 / P22 | Ferritic | 2.25% Chromium (Cr), 1% Molybdenum (Mo) | Widely used grade for high-temp strength & oxidation resistance. |
| T91 / P91 | Ferritic | 9% Chromium (Cr), 1% Molybdenum (Mo), Vanadium (V), Niobium (Nb) | Modern high-strength steel for high-pressure/temperature sections. |
| TP304 | Austenitic | 18% Chromium (Cr), 8% Nickel (Ni) | General-purpose stainless steel for corrosion resistance. |
| TP316 | Austenitic | 16% Chromium (Cr), 10% Nickel (Ni), 2% Molybdenum (Mo) | Improved corrosion resistance, especially to chlorides. |
General Chemical Composition Concept:
Unlike carbon steel specs (A192, A210), A213 grades are defined by specific alloy percentages. The table below shows the concept for a common low-alloy grade.
Example for Grade T11 (ladle analysis range):
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.05 - 0.15 |
| Manganese (Mn) | 0.30 - 0.60 |
| Phosphorus (P), max | 0.025 |
| Sulfur (S), max | 0.025 |
| Silicon (Si) | 0.50 - 1.00 |
| Chromium (Cr) | 1.00 - 1.50 |
| Molybdenum (Mo) | 0.44 - 0.65 |
Basic Mechanical Properties (Example):
Properties vary significantly by grade and heat treatment.
| Property (for T11, normalized & tempered) | Requirement |
|---|---|
| Tensile Strength, min | 415 MPa (60,000 psi) |
| Yield Strength, min | 205 MPa (30,000 psi) |
| Elongation, min | 30% (in 50mm) |
Main Comparison with A192 & A210:
A192/A210: For carbon steel tubes. Used where high temperature corrosion/oxidation is not the primary concern.
A213: For alloy steel tubes. Used where enhanced strength at high temperature, creep resistance, or corrosion/oxidation resistance is required. It is the go-to specification for alloy steel boiler and heat exchanger tubing.
