ASTM A312 TP347LN Austenitic Stainless Steel Pipes (UNS S34751)
ASTM A312 TP347LN (UNS S34751) is a nitrogen-enhanced, niobium-stabilized austenitic stainless steel grade. It provides exceptional intergranular corrosion resistance, improved mechanical strength, and enhanced pitting and crevice corrosion resistance compared to TP347. TP347LN is engineered for high-temperature, high-pressure, and aggressive chemical environments where superior structural stability and corrosion resistance are required.
Key Features
- Nitrogen-enhanced for superior strength and toughness
- Niobium-stabilized to resist intergranular corrosion
- Excellent resistance to pitting & crevice corrosion
- Improved performance over TP347 & TP347H in harsh environments
- Superior high-temperature oxidation and creep resistance
- Good weldability and formability
- Suitable for high-pressure and high-temperature piping systems
- Available in seamless, welded, and EFW forms
Equivalent Grades
| Standard |
Grade |
| ASTM |
TP347LN |
| UNS |
S34751 |
| WNR |
1.4961 Modified (Approx.) |
| EN |
X2CrNiNb18-10N (Nearest Equivalent) |
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 Cut Lengths
ASTM A312 TP347LN Chemical Composition
| Element |
Percentage (%) |
| Carbon (C) |
0.03 max |
| Manganese (Mn) |
2.00 max |
| Silicon (Si) |
1.00 max |
| Chromium (Cr) |
17.0 – 19.0 |
| Nickel (Ni) |
9.0 – 13.0 |
| Molybdenum (Mo) |
0.5 – 1.0 (typical, optional) |
| Niobium (Nb/Cb) |
≥ 10 × C (%) |
| Nitrogen (N) |
0.12 – 0.25 |
| Phosphorus (P) |
0.045 max |
| Sulfur (S) |
0.030 max |
| Iron (Fe) |
Balance |
ASTM A312 TP347LN Mechanical Properties
| Property |
Value |
| Tensile Strength |
≥ 550 MPa |
| Yield Strength (0.2% Proof) |
≥ 240 MPa |
| Elongation |
35% min |
| Hardness |
≤ 95 HRB |
| Modulus of Elasticity |
~193 GPa |
ASTM A312 TP347LN 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 |
0.76 µΩ·m |
| Coefficient of Expansion |
16.5 µm/m°C (20–100°C) |
Types of TP347LN Stainless Steel Pipes
- Seamless Stainless Steel Pipes
- Welded Stainless Steel Pipes
- EFW Stainless Steel Pipes
- Round Pipes
- Square Pipes
- Rectangular Pipes
- Superheater & Reheater Tubes
- Heat Exchanger & Condenser Pipes
- Custom Fabricated Pipes
Applications
- High-temperature & high-pressure pipelines
- Chemical and petrochemical industries
- Power generation & boiler systems
- Heat exchangers & condensers
- Oil & gas refinery piping
- Marine and offshore structures
- Pharmaceutical & food industry piping
- Fertilizer and pulp & paper plants
- Exhaust and flue gas systems
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