ASTM A312 TP347 Stainless Steel Pipe
ASTM A312 TP347 Stainless Steel Pipe: Composition, Properties & Equivalents
Detailed material data for ASTM A312 TP347 stainless steel pipe covering chemical composition, mechanical and physical properties, international equivalents, similar grades, and typical applications.
Hot/cold forming, machining, welding, bending, deep drawing
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ASTM A312 TP347 Stainless Steel Pipe Introduction
ASTM A312 TP347 is a niobium-stabilized austenitic stainless steel designed for superior resistance to intergranular corrosion, particularly after welding or at elevated temperatures. The addition of niobium prevents chromium carbide precipitation, maintaining corrosion resistance in the range of 425–860°C. This grade exhibits excellent high-temperature strength, good oxidation resistance, and is commonly used in demanding environments such as chemical processing, boiler tubes, and heat exchangers. It is non-magnetic in the annealed condition but may become slightly magnetic after cold working. Typical delivery condition is solution annealed and pickled, ensuring optimum ductility and corrosion resistance.
ASTM A312 TP347 Stainless Steel Pipe Chemical Composition according to ASTM A312
The chemical requirements for TP347 (UNS S34700) are specified in ASTM A312/A312M. The alloy is characterized by a niobium addition of at least 10 times the carbon content to ensure complete stabilization of carbon, thereby preserving intergranular corrosion resistance.
- Values are maximum unless a range is indicated.
- Niobium may be reported as Nb+Ta.
| Element | Specified Value | Notes |
|---|---|---|
| Carbon (C) | ≤ 0.08% | Maximum |
| Manganese (Mn) | ≤ 2.00% | Maximum |
| Phosphorus (P) | ≤ 0.045% | Maximum |
| Sulfur (S) | ≤ 0.030% | Maximum |
| Silicon (Si) | ≤ 1.00% | Maximum |
| Chromium (Cr) | 17.0 – 19.0% | Range |
| Nickel (Ni) | 9.0 – 13.0% | Range |
| Niobium (Nb) | 10×C min – 1.10% | Typically Nb+Ta, 10×C minimum |
ASTM A312 TP347 Stainless Steel Pipe Thermal and Electrical Physical Properties
The following physical properties are typical for TP347 (UNS S34700) stainless steel in the annealed condition. These values are based on published data from ASME and producer datasheets and should be considered approximate but suitable for engineering design.
- Properties can vary slightly depending on exact composition and processing.
- Thermal expansion and conductivity are temperature-dependent; values at multiple reference temperatures are provided.
| Property | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 8.0 | g/cm³ | At 20°C |
| Elastic Modulus (E) | 193 | GPa | At 20°C |
| Shear Modulus (G) | 77 | GPa | At 20°C (calculated) |
| Poisson's Ratio (ν) | 0.29 | - | At 20°C |
| Thermal Expansion Coefficient (α) | 16.6 | µm/m·°C | 20 – 100°C |
| Thermal Expansion Coefficient (α) | 17.2 | µm/m·°C | 20 – 315°C |
| Thermal Expansion Coefficient (α) | 18.0 | µm/m·°C | 20 – 538°C |
| Thermal Conductivity (λ) | 16.2 | W/m·K | At 100°C |
| Thermal Conductivity (λ) | 18.9 | W/m·K | At 300°C |
| Thermal Conductivity (λ) | 21.5 | W/m·K | At 500°C |
| Specific Heat Capacity (cp) | 500 | J/kg·K | At 20°C |
| Specific Heat Capacity (cp) | 540 | J/kg·K | At 300°C |
| Electrical Resistivity (ρ_e) | 0.72 | µΩ·m | At 20°C |
ASTM A312 TP347 Stainless Steel Pipe Mechanical Properties
The mechanical properties below represent the minimum required values for TP347 pipes in the solution-annealed condition, as per ASTM A312. Elongation requirements depend on the specimen type, which is determined by the wall thickness.
- For wall thickness ≥ 7.94 mm (5/16 in.), a standard round specimen is used.
- For thinner wall sections, a longitudinal strip test is employed with a lower elongation limit.
No impact test or hardness requirements are specified in the standard.
| Property | Minimum Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 515 | MPa | Room temperature, annealed |
| Yield Strength (ReH, 0.2% offset) | ≥ 205 | MPa | Room temperature, annealed |
| Elongation (A) | ≥ 35 | % | Standard round specimen, gauge length 50 mm (2 in.), wall ≥ 7.94 mm |
| Elongation (A) | ≥ 25 | % | Longitudinal strip test, gauge length 50 mm, wall < 7.94 mm |
ASTM A312 TP347 Stainless Steel Pipe Fully Equivalent Material Standards and Designations
| Country/Region | Standard | Designation | Notes |
|---|---|---|---|
| Europe | EN 10088-2 / EN 10216-5 | X6CrNiNb18-10 (1.4550) | Identical composition and stabilized grade |
| Japan | JIS G3459 / G3463 | SUS 347 TP | Austenitic stainless pipe grade equivalent to ASTM TP347 |
| China | GB/T 14976 / GB 13296 | 06Cr18Ni11Nb | UNS S34700 equivalent with minor range adjustments |
| International | ISO 9328-7 | X6CrNiNb18-10 | Harmonized standard for pressure purpose steel forgings and pipes |
ASTM A312 TP347 Stainless Steel Pipe Application Introduction
TP347 is selected for its superior resistance to intergranular corrosion in the as-welded condition and its high-temperature mechanical strength. It is extensively used in environments where both corrosion and creep resistance are required.
- Excellent for welded fabrications that cannot be post-weld heat treated.
- Used for superheater and reheater tubes in boilers.
- Suitable for service up to approximately 800°C under light cycling.
Product Applications: Seamless and welded pipes for conveyance of high-temperature fluids, Boiler tubes (superheater, reheater, economizer), Heat exchanger tubes, Condenser tubing, Instrumentation tubing, capillary tubes, Process piping for chemical plants
Processed into products: Welded pipe spools and headers, Tube bundles for shell-and-tube heat exchangers, Furnace tubes, Expansion joints and bellows, High-temperature gaskets and flanges, Thermowells and sensor protection tubes, Exhaust manifold components
Application industries: Chemical and petrochemical processing, Oil and gas refining, Power generation (fossil fuel and nuclear), Boiler and heat exchanger manufacturing, Aerospace (exhaust systems), Food processing (high-temperature cleaning), Marine engineering (high-strength fasteners)
ASTM A312 TP347 Stainless Steel Pipe Similar or Closely Related Material Alternatives
| Country/Region | Standard | Designation | Notes |
|---|---|---|---|
| USA | ASTM A312 | TP321 (UNS S32100) | Titanium-stabilized alternative; similar weldability and corrosion resistance, slightly lower elevated temperature strength. |
| USA | ASTM A312 | TP304 (UNS S30400) | Unstabilized predecessor; lower cost but susceptible to sensitization if not post-weld treated. Limited to non-aggressive service. |
| USA | ASTM A312 | TP304H (UNS S30409) | Higher carbon version for improved high-temperature strength; requires careful welding practice to avoid sensitization. |
| Europe | EN 10088-2 | X6CrNiTi18-10 (1.4541) | European designation for Ti-stabilized grade; direct alternative to TP321. |
Notes:
TP347 pipe is often supplied with a test certificate to EN 10204 type 3.1. For service above 540°C, it may be advisable to use the low carbon or controlled nitrogen version (e.g., TP347H) for enhanced creep strength. In some applications, solution annealing after welding is recommended to relieve residual stresses, though the stabilization generally avoids sensitization. For highly corrosive environments, consider super-austenitic or duplex stainless steels as an upgrade.
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