ASTM A312 TP347H Austenitic Stainless Steel Pipes
ASTM A312 TP347H (UNS S34709) is a niobium-stabilized, high-carbon austenitic stainless steel pipe grade designed for high-temperature service, superior creep strength, and excellent resistance to intergranular corrosion. The TP347H variant offers enhanced structural stability during prolonged exposure to elevated temperatures, making it highly suitable for furnace, boiler, and petrochemical service environments.
Key Features
- High-carbon, niobium-stabilized grade (UNS S34709)
- Superior creep, stress-rupture & high-temperature strength
- Excellent intergranular corrosion resistance
- High resistance to oxidation & carburization
- Strong performance under thermal cycling
- Improved weldability compared to 304H / 321H
- Suitable for long-term high-temperature structural applications
- Available in seamless, welded & EFW variants
✔ Equivalent Grades
| Standard | Equivalent |
|---|---|
| ASTM | TP347H |
| UNS | S34709 |
| WNR | 1.4961 |
| EN | X12CrNiNb18-10H (Nearest Equivalent) |
Available Sizes
Outer Diameter (OD):
-
6 mm to 610 mm
Wall Thickness:
-
1.2 mm to 60 mm
Nominal Bore (NB):
-
1/8” NB to 24” NB
Lengths:
-
SRL, DRL, Custom Cut Lengths up to 12 meters
ASTM A312 TP347H Chemical Composition
| Element | % |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Niobium/Columbium (Nb/Cb) | ≥ 10 × C (%), max 1.00 |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
ASTM A312 TP347H Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Proof) | ≥ 205 MPa |
| Elongation | 40% min |
| Hardness | ≤ 95 HRB |
| Modulus of Elasticity | ~193 GPa |
ASTM A312 TP347H Physical Properties
| Property | Value |
|---|---|
| Density | 7.90 g/cm³ |
| Melting Point | 1398–1446°C |
| Thermal Conductivity | 16.3 W/m·K (100°C) |
| Electrical Resistivity | 0.78 µΩ·m |
| Coefficient of Expansion | 16.5 µm/m°C (20–100°C) |
Types of TP347H Stainless Steel Pipes
- Seamless Pipes
- Welded Pipes
- EFW (Electric Fusion Welded) Pipes
- Round Pipes
- Square Pipes
- Rectangular Pipes
- Heat Exchanger & Boiler Pipes
- Custom Fabricated Pipes
Applications
- High-temperature steam & boiler systems
- Furnace components & heat treatment equipment
- Superheater & reheater tubes
- Petrochemical and refinery piping
- Thermal power plant equipment
- Chemical processing industry
- Heat exchangers & radiant tubes
- Exhaust and high-temperature gas handling
- Oil & gas refinery pipelines
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