ASTM A213 TP348H Stainless Steel Tubes (UNS S34809)
ASTM A213 TP348H Stainless Steel Tubes (UNS S34809) are high-carbon, niobium-stabilized austenitic stainless steel tubes designed expressly for long-term high-temperature and high-pressure environments. The “H” grade in TP348H signifies enhanced carbon content, resulting in greater creep strength, stress-rupture resistance, and improved performance in continuous elevated-temperature service above 600°C.
TP348H is used extensively in superheaters, boilers, refinery heaters, petrochemical processing units, steam pipelines, and heat exchangers, where temperature stability and mechanical durability are crucial. Its superior oxidation resistance, excellent surface finish, and stable performance under thermal cycling make it a preferred material in energy, power generation, and chemical industries. The TP348H grade ensures reliable long-term service, reduced downtime, and optimal heat-transfer efficiency.
Key Features
- High-carbon variant for increased creep and stress-rupture strength
- Niobium-stabilized for superior intergranular corrosion resistance
- Outstanding high-temperature oxidation and scaling resistance
- Performs reliably in continuous service up to 870°C
- Smooth internal surface ensures efficient heat transfer
- Excellent mechanical durability in high-pressure steam systems
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | S34809 |
| WNR | 1.4551 (High Carbon Variant) |
| EN | X6CrNiNb18-10 (Modified for H Grade) |
Available Sizes
- Outside Diameter: 6 mm to 114.3 mm
- Wall Thickness: 1.0 mm to 12.7 mm
- Length: Up to 12 meters (custom lengths available)
ASTM A213 TP348H Chemical Composition
| Element | % |
|---|---|
| Carbon (C) | 0.04–0.10 |
| Chromium (Cr) | 17.0–19.0 |
| Nickel (Ni) | 9.0–13.0 |
| Niobium/Columbium (Nb/Cb) | 10 × C min – 1.00 max |
| Manganese (Mn) | ≤2.00 |
| Silicon (Si) | ≤0.75 |
| Phosphorus (P) | ≤0.045 |
| Sulfur (S) | ≤0.030 |
| Nitrogen (N) | ≤0.10 |
ASTM A213 TP348H Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥550 MPa |
| Yield Strength | ≥205 MPa |
| Elongation | ≥35% |
| Hardness | ≤192 HB |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ |
| Melting Range | 1398–1454°C |
| Thermal Conductivity | 16 W/m-K |
| Elastic Modulus | 193 GPa |
| Electrical Resistivity | 0.73 µΩ-m |
Type of ASTM A213 TP348H Tube
- Seamless Boiler Tubes
- Seamless Superheater Tubes
- Heat Exchanger Tubes
- Pressure Tubes
- High-Temperature Heater Tubes
Applications
- Power Plant Boilers & Reheaters
- Superheaters Operating at High Pressures
- Refinery Furnace & Heater Tubes
- High-Temperature Petrochemical Piping
- Steam Boilers & Turbine Heat Lines
- Chemical Processing Heat-Transfer Units
- Industrial Heating Systems Exposed to Thermal Cycling
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