Seamless Stainless Steel TP347H Tube
Seamless Stainless Steel TP347H tubes are high-performance austenitic stainless steel tubing solutions stabilized with niobium (columbium), specifically engineered for elevated temperature service and enhanced creep resistance. Designed for long-term exposure to high temperatures, Stainless Steel 347H Seamless Tubes (UNS S34709 / DIN 1.4961) provide excellent intergranular corrosion resistance and superior mechanical strength in demanding industrial environments.
GZH is a trusted TP347H seamless stainless steel tube manufacturer and supplier based in Wenzhou, China, with extensive experience in precision pipe manufacturing. We produce premium-quality SS 347H seamless tubes that meet strict international quality standards and high-pressure application requirements.
Standards & Specifications
Our TP347H seamless tubes are manufactured in compliance with:
ASTM A213/ASME SA213/DIN 1.4961/UNS S34709
Key Features of TP347H Seamless Tubes
Excellent high-temperature strength and creep resistance
Superior resistance to intergranular corrosion
Good oxidation resistance in elevated temperature environments
Stable mechanical properties under pressure
Precise dimensional tolerances and smooth surface finishes
We offer a comprehensive range of outer diameters, wall thicknesses, and pressure ratings to meet diverse industrial specifications. Custom cut-to-length services and bulk supply options are available for EPC contractors and large-scale industrial projects.
"Our precision-controlled Niobium content (Nb ≥ 8 X C) ensures complete stabilization of carbides, providing maximum resistance to sensitization and intergranular attack even after welding."
What Is a Seamless Stainless Steel TP347H Tube?
Seamless Stainless Steel TP347H Tube is a high-performance, precision-engineered tube crafted from a single, solid billet of a niobium-stabilized austenitic stainless steel alloy. Unlike welded tubes, it has no weld joint, ensuring superior structural integrity and reliability, especially under high-stress and high-temperature conditions. The"347H"designation refers to a specific grade that is a high-carbon version of Stainless Steel 347. This higher carbon content (0.04-0.10%) provides enhanced creep and stress-rupture properties at elevated temperatures, making it a preferred choice for applications where long-term high-temperature strength and stability are critical. Like Stainless Steel 347, it is stabilized with niobium to prevent the formation of chromium carbide precipitates and subsequent intergranular corrosion.
Key Features and Advantages
TP347H Seamless Tube offer a unique combination of benefits that make them invaluable in demanding high-temperature environments:
Excellent High-Temperature Strength: The higher carbon content provides superior creep and stress-rupture properties, ensuring long-term structural stability at temperatures exceeding 1100°F (593°C).
High-Temperature Stability: The niobium stabilization prevents carbide precipitation, ensuring the material maintains its corrosion resistance and structural integrity even after being exposed to high temperatures.
Good Corrosion Resistance: It provides good resistance to a wide range of corrosive media, similar to standard 304 stainless steel.
High Pressure and Temperature Tolerance: The seamless construction and robust material allow the tube to safely handle high internal pressures and extreme temperatures.
Superior Weldability: The stabilized composition allows for excellent weldability without the need for post-weld annealing, simplifying fabrication.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Stainless Steel 347H.
Table 1: Chemical Composition of Stainless Steel 347H
The composition of Stainless Steel 347H is carefully balanced to achieve its superior high-temperature strength and corrosion resistance.
Grade | C | Cr | Ni | Mn | P | S | Si | Other |
| 347 | ≤0.08 | 17.00-19.00 | 9.00-13.00 | ≤2.00 | ≤0.035 | ≤0.030 | ≤1.00 | Nb≥10*C% |
| 347H | 0.04-0.10 | 17.00-19.00 | 9.00-13.00 | ≤2.00 | ≤0.035 | ≤0.030 | ≤1.00 | Nb≥8*C% |
Note: The niobium content must be at least eight times the carbon content to ensure stabilization.
Table 2: Typical Mechanical Properties of Stainless Steel 347H
Stainless Steel 347H is specifically designed to maintain its strength and shape in high-temperature, high-stress environments.
Grade | Yield strength ksi(MPa) | Tensile Strength ksi(MPa) | Elongation % | Hardness Brinell/Vickers | Hardness Rockwell |
| 347 | ≥30(205) | ≥75(515) | ≥35 | ≤192 HBW/200HV | ≤90HRB |
| 347H | ≥30(205) | ≥75(515) | ≥35 | ≤192 HBW/200HV | ≤90HRB |
Table 3: Typical Physical Properties of Stainless Steel 347H
These physical properties highlight the material's ability to perform reliably under a wide range of conditions.
| Property | Value |
| Density | 8.0 g/cm³ |
| Melting Point | 1398 - 1454 °C |
| Thermal Expansion | 16.6 µm/m·°C (20-100°C) |
| Thermal Conductivity | 16.3 W/m·K (20°C) |
| Modulus of Elasticity | 193 GPa |
| Electrical Resistivity | 0.72 x 10⁻⁶ Ω·m (20°C) |
Table 4: The Standard of Stainless Steel Seamless Tube Size Tolerance Size Chart :
| Standard | OD(D) | Tolerance（MM) | Thickness(S) | Tolerance(MM) | Length | Tolerance | |
| MM | Common | High | MM | MM | |||
| EN 10216-5 HFD | 30≤D≤219.1（D2) | ±1.0% or ±0.5mm, whicever is the greater(取较大者) | T1, T≤4 | ±15% or ±0.6mm, whicever is the greater(取较大者) | L≤6M | +5/0 | |
| T2 | ±12.5% or ±0.4mm, whicever is the greater(取较大者) | ||||||
| 219.1≤D≤610 (D1) | ±1.5% or ±0.75mm, whicever is the greater (取较大者) | T≤0.05D | +22.5%/-15% | 6 | +10/0 | ||
| T1, 0.05D | ±15% or ±0.6mm, whicever is the greater(取较大者) | ||||||
| T2, T>0.09D | ±12.5% or ±0.4mm, whicever is the greater(取较大者) | L>12 | +by agreement/0 | ||||
| EN 10216-5 CFD | D3(D≤219.1) | ±0.75% or ±0.3mm, whicever is the greater(取较大者) | T3 | ±10% or ±0.2mm, whicever is the greater(取较大者) | |||
| D4(D≤219.1) | ±0.5% or ±0.mm, whicever is the greater(取较大者) | T4 | ±7.5% or ±0.15mm, whicever is the greater(取较大者) | ||||
| ASTM A213 HFD | D≤100 | +0.4/-0.8 | D<100,S≤2.4 | +40%/0 | HFD, all size | +5.0/0 | |
| +0.4/-1.2 | D<100,2.4 | +35%/0 | |||||
| +0.4/-1.6 | D<100,3.8 | +33%/0 | |||||
| D<100,S>4.6 | +28%/0 | ||||||
| 100 | +0.4/-1.2 | D>100, 2.4 | +35%/0 | ||||
| 200 | +0.4/-1.6 | D>100,3.8 | +33%/0 | ||||
| D>100,S>4.6 | +28%/0 | ||||||
| ASTM A213 CFD | D<25 | ±0.10 | D≤38.1 | +20%/0 | CFD, D<50.8 | +3.0/0 | |
| 25≤D≤40 | ±0.15 | ||||||
| 40 | ±0.20 | ||||||
| 50≤D<65 | ±0.25 | ||||||
| 65≤D<75 | ±0.30 | D>38.1 | +22%/0 | CFD, D≥50.8 | +5.0/0 | ||
| 75≤D≤100 | ±0.38 | ||||||
| 100 | +0.38/-0.64 | ||||||
| 200 | +0.38/-1.14 | ||||||
| ASTM A269 | D≤13 | ±0.13 | D≤13 | ±15% | D<38 | +3.2/0 | |
| 13 | ±0.13 | 13 | ±10% | ||||
| 38≤D<89 | ±0.25 | D>38 | +4.8/0 | ||||
| 89≤D<140 | ±0.38 | ||||||
| 140≤D<203 | ±0.76 | ||||||
| 203≤D<305 | ±1.01 | ||||||
| 305≤D<356 | ±1.26 | ||||||
| ASTM A270 | D<25 | ±0.13 | For weld pipe all size | ±12.5% | +3.0/0 | ||
| 25-50 | ±0.20 | ||||||
| 50-75 | ±0.25 | ||||||
| 75-100 | ±0.38 | For CD SMLS pipe D≤38.1 | +20%/0 | ||||
| 100-140 | ±0.38 | +5.0/0 | |||||
| 140-200 | ±0.75 | For CD SMLS pipe D>38.1 | +22%/0 | ||||
| 200-300 | ±1.25 | ||||||
Common Applications
The combination of high-temperature strength and excellent corrosion resistance of seamless Stainless Steel 347H tubes makes them a preferred choice for:
Power Generation: Used in superheater and reheater tubes for boilers where long-term high-temperature stability is critical.
Aerospace: In jet engine components, exhaust manifold tubing, and high-temperature fasteners.
Chemical and Petrochemical Processing: For furnace parts, heat exchangers, and expansion joints where temperatures are in the carbide precipitation range.
Waste Incineration: For components in waste incinerators and combustion chambers.
Manufacturing Process
The manufacturing of a TP347H Stainless Steel Seamless Tube is a precise, multi-step process:
- Heating: A solid billet of Stainless Steel 347H is heated to a high temperature.
- Piercing: A piercing mill pushes a mandrel through the center of the heated billet to form a hollow shell.
- Drawing and Sizing: The hollow shell is then rolled and drawn to reduce its diameter and wall thickness to the desired dimensions.
- Heat Treatment: The tube is solution annealed at a high temperature to achieve the specified metallurgical properties and to ensure optimal performance.
- Finishing: The tube is cut to length, straightened, and subjected to rigorous testing to ensure it meets the highest standards for performance and reliability. This meticulous process ensures that every seamless Stainless Steel 347H tube is built to withstand the most extreme operating conditions.
