ASTM A312 TP347 Austenitic Stainless Steel Pipes (UNS S34700)
ASTM A312 TP347 (UNS S34700) is a niobium-stabilized austenitic stainless steel grade developed to resist intergranular corrosion and carbide precipitation after welding or exposure to elevated temperatures. With improved high-temperature creep and strength characteristics, TP347 is ideal for applications requiring durability, corrosion resistance, and thermal stability in demanding environments.
Key Features
- Niobium-stabilized for superior intergranular corrosion resistance
- Excellent high-temperature strength and creep resistance
- Good performance under thermal cycling and oxidation
- Superior weldability and formability
- Maintains stability during long-term heat exposure
- Highly resistant to chemical, acidic, and chloride environments
- Suitable for welding-intensive and high-pressure systems
- Available in seamless, welded, and EFW pipe types
Equivalent Grades
| Standard | Grade |
|---|---|
| ASTM | TP347 |
| UNS | S34700 |
| WNR | 1.4550 |
| EN | X6CrNiNb18-10 |
| JIS | SUS 347 |
| BS | 347S17 |
Available Sizes
- Outer Diameter (OD): 6 mm to 610 mm
- Wall Thickness: 1.2 mm to 60 mm
- Nominal Bore: 1/8” NB to 24” NB
- Lengths: SRL, DRL, Custom up to 12 meters
ASTM A312 TP347 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 |
| Niobium (Nb/Cb) | ≥ 10 × C (%) |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
ASTM A312 TP347 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Proof) | ≥ 205 MPa |
| Elongation | 35% min |
| Hardness | ≤ 95 HRB |
| Modulus of Elasticity | ~193 GPa |
ASTM A312 TP347 Physical Properties
| Property | Value |
|---|---|
| Density | 7.90 g/cm³ |
| Melting Range | 1398 – 1450°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 TP347 Stainless Steel Pipes
- Seamless Stainless Steel Pipes
- Welded Stainless Steel Pipes
- EFW Stainless Steel Pipes
- Round Pipes
- Square Pipes
- Rectangular Pipes
- Heat Exchanger & Superheater Tubes
- Custom Fabricated Pipes
Applications
- High-temperature steam & boiler systems
- Petrochemical and refinery piping
- Furnace components & heat treatment systems
- Superheater and reheater tubes
- Chemical processing equipment
- Heat exchangers & condensers
- Power generation equipment
- Pharmaceutical & food processing lines
- Oil & gas pipelines
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