Seamless Stainless Steel TP347H Pipe
Distinguished by the strategic addition of Niobium (Nb) and an optimized carbon content, our TP347H tubing ensures exceptional stability and resistance to intergranular corrosion at service temperatures up to 815°C (1500°F). These pipes are indispensable for mission-critical applications in superheater tubes, reheater coils, and high-pressure steam systems. Through advanced cold-drawing and precise solution annealing, GZH guarantees a uniform grain structure and maximum durability under intense thermal stress.
“Our precision control over the Niobium-to-Carbon ratio ensures that carbides are fully stabilized, preventing sensitization and maintaining superior structural integrity during prolonged high-temperature service.”
What Is a Seamless Stainless Steel TP347H Pipe?
TP347H Seamless Stainless Steel Pipe is a cylindrical tube crafted from a single, solid billet of stainless steel. Like other seamless products, it has no weld joint, which ensures superior structural integrity and reliability.
The"347H"designation signifies a high-carbon version of the 347 grade. The higher carbon content provides significantly improved creep rupture strength, which is crucial for components that must endure continuous stress under extreme heat without deforming over time. This makes TP347H a top choice for high-temperature structural applications. It retains the same excellent resistance to oxidation, scaling, and intergranular corrosion as the standard TP347H grade, thanks to its niobium (columbium) stabilization.
Key Features and Advantages
Seamless TP347H Stainless Steel Pipe offer a unique combination of benefits that make them invaluable in the most demanding industries:
Superior Creep Rupture Strength: The high carbon content is the primary differentiator, providing enhanced strength and resistance to deformation under sustained high temperatures. This is critical for long-term reliability.
Exceptional Resistance to Intergranular Corrosion: The niobium/tantalum stabilization prevents carbide precipitation during welding and high-temperature service, ensuring the material retains its corrosion-fighting properties in all conditions.
Excellent High-Temperature Performance: It performs exceptionally well in temperatures up to 870°C (1600°F), with better high-temperature strength and creep resistance than the standard 347 grade.
High Pressure Tolerance: The seamless construction eliminates a potential weak point, allowing the pipe to safely handle high internal pressures, which is critical in many high-temperature processes.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for 347H stainless steel.
Table 1: Chemical Composition of TP347H Stainless Steel
The enhanced strength of TP347H is a direct result of its high carbon content, while retaining the essential niobium, chromium, and nickel levels for heat 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% |
Table 2: Typical Mechanical Properties of TP347H Stainless Steel
Grade 347H is specifically designed to maintain its strength and shape in high-stress, high-temperature applications.
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 TP347H Stainless Steel
These physical properties highlight the material's ability to perform reliably under extreme thermal 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 Pipe Size Tolerance Size Chart :
| Standard | OD(D) | Tolerance（MM) | Thickness(S) | Tolerance(MM) | Length | Tolerance | |
| MM | Common | High | MM | MM | |||
| ASTM A312 | D≤48.3 | +0.4/-0.8 | 10.3 | +20%-12.5% | +6.0/0 | ||
| 48.3 | ±0.8 | 88.9 | +22.5%/-12.5% | ||||
| 114.3 | +1.6/-0.8 | 88.9 | +15%/-12.5% | ||||
| 219.1 | +2.4/-0.8 | D≥508, t/D≤5%,SMLS | +22.5%/-12.5% | ||||
| 457.2 | +3.2/-0.8 | D≥508, t/D>5%,SMLS | +15%/-12.5% | ||||
| 660.4 | +4.0/-0.8 | D≥508, WELD | +17.5%/-12.5% | ||||
| 863.6 | +4.8/-0.8 | ||||||
| JIS 3459 Hot-Finished Smls Pipe | D＜50 | ±0.51 | S＜4 | ±0.5 | |||
| D≥50 | ±1.0% | S≥4 | ±12.5% | ||||
| JIS 3459 Cold-Finished | D＜30 | ±0.3 | S＜2 | ±0.2 | |||
| D≥30 | ±1.0% | S≥2 | ±10.0% | ||||
| JIS G3463 Hot-Finished Smls Pipe | 100 | +0.4/-0.8 | D＜100， S<2 | / | D<50, L<7M | +7/0 | |
| D＜100， 2≤S<2.4 | +40%/0 | D<50,7< L<10M | +10/0 | ||||
| D＜100， 2.4≤S<3.8 | +35%/0 | ||||||
| D＜100， 3.8≤S<4.6 | +33%/0 | ||||||
| D＜100， 4.6≤S | +28%/0 | D<50,10< L<13M | +13/0 | ||||
| 100≤D<120 | +0.4/-1.2 | D>100, S＜2 | / | ||||
| 120≤D<160 | D>100， 2≤S<2.4 | / | D<50,13M< L | +15/0 | |||
| 160≤D<200 | +0.4/-1.8 | D>100， 2.4≤S<3.8 | +35%/0 | ||||
| 200≤D | +0.4/-2.4 | D>100， 3.8≤S<4.6 | +33%/0 | D>50,7< L<7M | +10/0 | ||
| D>100， 4.6≤S | +28%/0 | ||||||
| JIS G3463 Cold-finished | <60 | +0.4/-0.8 | D<40, S<2.0 | +0.4/0 | |||
| 60≤D<80 | ±0.3 | D<40, S≥2.0 | +20%/0 | D>50,7< L<10M | +13/0 | ||
| 80≤D<100 | ±0.4 | D≥40 | +22%/0 | ||||
| 100≤D<120 | +0.4/-0.6 | ||||||
| 120≤D<160 | +0.4/-0.8 | D>50,10M< L | +15/0 | ||||
| 160≤D<200 | +0.4/-1.2 | ||||||
| 200≤D | +0.4/-1.6 | ||||||
| GB/T 14975 冷拔(扎)钢管 | D<12.7 | ±0.3 | ±0.1 | 所有壁厚，普通级PA | +12.5%/-10% | ||
| 12.7 | ±0.15 | ||||||
| 38.1 | ±0.4 | ±0.3 | |||||
| 88.9 | ±0.9% | ±0.4 | |||||
| 139.7 | ±0.8 | 所有壁厚，高级PC | ±10% | ||||
| 203.2 | ±1.1 | ||||||
| 219.1 | ±1.6 | ||||||
| D≥323.9 | ±0.5% | ||||||
| GB/T 14976 冷拔(轧)钢管 | 6 | ±0.2 | ±0.15 | S≤3 | ±12%(10% /0高级PC) | ||
| 10≤D<30 | ±0.2 | ±0.2 | |||||
| 30≤D<50 | ±0.2 | ±0.3 | S>3 | +12.5%/-10%(10%/0高级PC) | |||
| 50≤D<219 | 0.85% | 0.75% | |||||
| D>219 | 0.9% | 0.8% | Smin, all | +22%/0(+20%/0高级PC) | |||
Common Applications
The enhanced creep resistance of Seamless Stainless Steel TP347H Pipe makes them a preferred choice for:
Aerospace: Used in jet engine parts, exhaust manifolds, and afterburners where components must endure high temperatures and loads over extended periods.
Chemical Processing: In systems handling corrosive chemicals and gases at high temperatures under structural load.
Thermal Oxidizers and Boilers: For components that are exposed to high heat and corrosive conditions, such as boiler tubes and hangers.
Refineries: Used in piping for high-temperature and high-pressure applications.
Manufacturing Process
The manufacturing of a TP347H Stainless Steel Seamless Pipe is a precise, multi-step process:
- Heating: A solid steel billet 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.
- Rolling and Sizing: The hollow shell is then rolled and drawn to reduce its diameter and wall thickness to the desired dimensions.
- Finishing: The pipe is cut to length, heat-treated, and subjected to finishing processes like pickling to achieve its final state.
This meticulous process ensures that every 347H seamless pipe meets the highest standards for performance and reliability in the most demanding applications.
