ASME SA312 TP347 Stainless Steel Pipe
ASME SA312 TP347 Stainless Steel Pipe: High-Temperature Austenitic Alloy Guide
Comprehensive material data for ASME SA312 TP347 austenitic stainless steel pipe, including chemical composition, mechanical & thermal properties, international equivalents, and applications in high-temperature services.
Hot-rolled or cold-drawn seamless; seam-welded with or without filler metal; solution annealed at 1900°F (1040°C) minimum
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ASME SA312 TP347 Stainless Steel Pipe Introduction
ASME SA312 TP347 is a niobium-stabilized austenitic stainless steel pipe intended for high-temperature service. It belongs to the 18Cr-10Ni family and offers excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range (800–1600°F / 427–871°C). The addition of niobium (columbium) prevents sensitization and maintains mechanical properties in creep environments. This material is widely used in boilers, superheaters, heat exchangers, and petrochemical piping where resistance to oxidizing media and thermal stability are required. Typical delivery conditions include solution-annealed state, ensuring uniform microstructure and compliance with the ASME Boiler and Pressure Vessel Code Section II.
ASME SA312 TP347 Stainless Steel Pipe Chemical Composition
The chemical composition of ASME SA312 TP347 conforms to the requirements of ASME SA312/SA312M. Niobium (columbium) addition stabilizes the alloy against sensitization. Maximum limits are strictly controlled to ensure weldability and corrosion resistance.
| Element | Standard Value (wt.%) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.08 | |
| Manganese (Mn) | ≤ 2.00 | |
| Phosphorus (P) | ≤ 0.045 | |
| Sulfur (S) | ≤ 0.030 | |
| Silicon (Si) | ≤ 1.00 | |
| Chromium (Cr) | 17.0 – 19.0 | |
| Nickel (Ni) | 9.0 – 13.0 | |
| Niobium + Tantalum (Nb+Ta) | 10 × C min / 1.00 max | Stabilizing addition to prevent intergranular corrosion |
ASME SA312 TP347 Stainless Steel Pipe Thermal and Electrical Physical Properties
The following physical properties are typical for annealed TP347 (S34700) stainless steel. Exact values may vary with minor chemistry and processing. Data are applicable in the annealed condition.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.90 – 8.00 | g/cm³ | Room temperature |
| Elastic Modulus (E) | 193 – 200 | GPa | 20 °C |
| Shear Modulus (G) | 76 – 80 | GPa | 20 °C |
| Poisson's Ratio (ν) | 0.27 – 0.30 | Dimensionless | 20 °C |
| Thermal Expansion Coefficient (α) | 16.0 – 17.0 | µm/m·°C | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 17.0 – 18.0 | µm/m·°C | 20 – 300 °C |
| Thermal Conductivity (λ) | 14.0 – 16.0 | W/m·K | 20 °C |
| Thermal Conductivity (λ) | 16.0 – 19.0 | W/m·K | 100 °C |
| Specific Heat Capacity (cₚ) | 500 | J/kg·K | Room temperature |
| Electrical Resistivity (ρₑ) | 0.72 – 0.73 | µΩ·m | 20 °C |
ASME SA312 TP347 Stainless Steel Pipe Mechanical Properties
Mechanical properties are measured at room temperature on longitudinal test specimens. Requirements vary with wall thickness. The values below are the minimum specified in ASME SA312.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 515 | MPa | Room temperature |
| Tensile Strength (Rm) | ≥ 75 | ksi | Room temperature |
| Yield Strength (ReH, 0.2% offset) | ≥ 205 | MPa | Room temperature |
| Yield Strength (ReH, 0.2% offset) | ≥ 30 | ksi | Room temperature |
| Elongation (A, in 50 mm or 2 in.) | ≥ 35 | % | Wall thickness ≤ 7.94 mm (5/16 in.) |
| Elongation (A, in 50 mm or 2 in.) | ≥ 30 | % | Wall thickness > 7.94 mm (5/16 in.) |
| Bend Test | Not required for seamless pipe unless specified; for welded pipe, guided-bend test required | Per standard |
ASME SA312 TP347 Stainless Steel Pipe Exact Matching International Standards & Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASME SA312 / ASTM A312 | TP347 | Identical to S34700; seamless/welded pipe |
| Europe | EN 10216-5 (Seamless) / EN 10217-7 (Welded) | X6CrNiNb18-10 (1.4550) | Full equivalence; Nb-stabilized 18-10 |
| Japan | JIS G3459 / G3459 | SUS347TP | Seamless/welded stainless steel pipe |
| China | GB/T 14976 / GB/T 14975 | 06Cr18Ni11Nb (0Cr18Ni11Nb) | Seamless/welded tubing |
| International | ISO 9329-2 / ISO 9330-5 | X6CrNiNb18-10 | ISO designation for pressure purposes |
ASME SA312 TP347 Stainless Steel Pipe Application Introduction
ASME SA312 TP347 pipes are engineered for sustained operation at temperatures up to 1500°F (816°C) in oxidizing environments. The niobium stabilization renders the alloy immune to intergranular attack after welding or slow cooling. Typical service fluids include high-temperature steam, hot petroleum products, and corrosive chemicals.
- Solution Annealing ensures best ductility and creep resistance.
- Excellent weldability with matching filler metals (ER347).
- Not recommended for strongly reducing environments or molten salts without evaluation.
Product Applications: Superheater and reheater tube assemblies, Shell-and-tube heat exchangers, Process piping systems for hot hydrocarbons, Indirect-fired water heaters, Catalytic reformer tubes, Waste heat recovery boilers
Processed into products: Seamless boiler tubes (SA213 TP347 equivalent for tubing), Return bends and U-bends for heat exchangers, Welded pipe spools with flanges, Reducer and tee fittings for high-temperature headers, Forged flanges from S34700 (ASME SA182 F347), Expansion joints and bellows (using cold-formed pipe)
Application industries: Power Generation (boiler tubes, superheater & reheater circuits), Petrochemical & Refinery (furnace tubes, transfer lines), Chemical Processing (high-temperature reactors, heat exchangers), Oil & Gas (downhole tubing, process piping), Pulp & Paper (digester heaters), Pharmaceutical & Food (where high-temperature sterilization required)
ASME SA312 TP347 Stainless Steel Pipe Closely Related / Near-Equivalent Alternatives
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A312 | TP321 (UNS S32100) | Titanium-stabilized 18-10; similar weldability and intergranular corrosion resistance; slightly lower high-temperature strength |
| USA | ASTM A312 | TP304H (UNS S30409) | High-carbon 18-8; higher strength at elevated temperature but susceptible to sensitization without stabilization |
| Europe | EN 10216-5 | X6CrNiTi18-10 (1.4541) | Ti-stabilized equivalent to TP321 |
| Europe | EN 10216-5 | X6CrNiMoTi17-12-2 (1.4571) | Mo + Ti stabilized; improved pitting resistance but can be substituted where temperature and corrosion conditions permit |
Notes:
- Solution annealing temperature must not be lower than 1900°F (1040°C) followed by quenching in water or rapid air cooling.
- When welded, interpass temperature should be kept below 300°F (150°C) to avoid hot cracking; filler metal ER347 is recommended.
- For ASME B31.1 and B31.3 piping design, allowable stress values for TP347 are listed in the ASME Boiler & Pressure Vessel Code Section II, Part D.
- Hardness values are not specified in the standard but typically range from 90 to 180 HBW.
- Pressure testing is mandatory per specification (hydrostatic or nondestructive electric test).
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