ASTM A376 TP347H HFW Solid Finned Tube With 11Cr Fins For Power plant boilers
ASTM A376 TP347H HFW Solid Finned Tube with 11Cr Fins refers to a high-performance finned tube used in high-temperature and high-pressure applications, particularly in boilers, heat exchangers, and superheaters. Here's a breakdown of its components:
1. Base Tube: ASTM A376 TP347H
ASTM A376: Standard specification for seamless austenitic steel pipes for high-temperature service.
TP347H: A grade of austenitic stainless steel with:
High chromium (Cr) and nickel (Ni) content (typically 17-19% Cr, 9-12% Ni).
Stabilized with niobium (Nb) to prevent carbide precipitation (improves corrosion resistance at high temps).
"H" designation indicates high carbon content (0.04-0.10%) for enhanced creep strength at elevated temperatures.
(1). Chemical Composition (Weight %)
| Element | ASTM A376 TP347H Requirements | Remarks |
| Carbon (C) | 0.04 – 0.10 | High carbon ("H" grade) for creep resistance. |
| Manganese (Mn) | ≤ 2.00 | Improves strength and hot workability. |
| Phosphorus (P) | ≤ 0.045 | Low to avoid brittleness. |
| Sulfur (S) | ≤ 0.030 | Minimized for weldability. |
| Silicon (Si) | ≤ 1.00 | Enhances oxidation resistance. |
| Chromium (Cr) | 17.0 – 20.0 | Provides corrosion/oxidation resistance. |
| Nickel (Ni) | 9.0 – 13.0 | Stabilizes austenitic structure. |
| Niobium (Nb) | 10 × C min. – 1.10 max. | Prevents sensitization (forms NbC instead of Cr-carbides). |
| Iron (Fe) | Balance | Base metal. |
(2). Mechanical Properties (Room Temperature)
| Property | ASTM A376 TP347H Requirements | Notes |
| Tensile Strength (MPa) | ≥ 515 | High strength at elevated temps. |
| Yield Strength (0.2% offset, MPa) | ≥ 205 | Sufficient for high-pressure applications. |
| Elongation (% in 50mm) | ≥ 35 | Good ductility. |
| Hardness (Brinell HB) | ≤ 201 | Typically ~160–190 HB. |
2. HFW (High-Frequency Welded)
The tube is manufactured using high-frequency induction welding, a process that ensures a strong, consistent weld seam. HFW tubes are cost-effective alternatives to seamless tubes while maintaining good mechanical properties.
3. Solid Finned Tube
The tube has externally attached fins to increase heat transfer efficiency.
Solid fins mean the fins are mechanically bonded (e.g., welded, extruded) to the tube, ensuring durability under thermal cycling.
4. 11Cr Fins
The fins are made of 11% chromium (11Cr) steel, a material chosen for:
- High-temperature oxidation resistance (better than carbon steel fins).
- Compatibility with the TP347H base tube in thermal expansion and corrosion resistance.
- Common in power plants and waste heat recovery systems where sulfur and other corrosive elements are present.
The ASTM A376 TP347H HFW Solid Finned Tube with 11Cr Fins is designed for high-temperature, high-pressure, and corrosive environments, making it ideal for industries where heat transfer efficiency and material durability are critical. Here are its key applications:
1. Power Generation (Coal, Gas & Waste-to-Energy Plants)
- Superheaters & Reheaters:
- Used in boilers to convert saturated steam into superheated steam (typically at 550–700°C).
- The TP347H base tube resists creep, while 11Cr fins withstand flue gas corrosion (e.g., sulfur, chlorides).
- Heat Recovery Steam Generators (HRSGs):
- Recovers waste heat from gas turbines to produce steam.
- HFW (High-Frequency Welded) construction balances cost and performance.
2. Petrochemical & Refinery Heaters
- Fired Heaters & Cracking Furnaces:
- Handles high-sulfur fuels and acidic gases (e.g., H₂S, SOₓ).
- 11Cr fins resist sulfidation (better than carbon steel or 304H fins).
- Catalytic Reformer Units:
- Operates at 600–800°C; TP347H’s niobium stabilization prevents sensitization.
3. Waste Incineration & Biomass Boilers
- Corrosive Flue Gas Environments:
- Combats chlorine, alkali metals, and fly ash (common in waste/ biomass combustion).
- Solid fins ensure mechanical stability under thermal cycling.
4. Chemical Processing
- High-Temperature Reactors & Exchangers:
- Used in ammonia, methanol, and sulfuric acid production.
- HFW tubes reduce costs vs. seamless alternatives without sacrificing performance.
5. Oil & Gas (Upstream & Midstream)
- Exhaust Gas Boilers (EGBs):
- Recovers heat from diesel engine exhausts on ships/offshore platforms.
- 11Cr fins resist saltwater-induced pitting and erosion.
Why This Combination?
| Component | Role in Application |
| ASTM A376 TP347H | High creep strength (H-grade carbon), oxidation resistance up to 750°C. |
| HFW Tube | Cost-effective welded alternative to seamless tubes, suitable for high pressure. |
| Solid 11Cr Fins | Resists sulfidation/oxidation; outperforms carbon steel in corrosive flue gas. |
Advantages Over Alternatives
- VS. TP304H Finned Tubes: Better for high-sulfur environments (11Cr > 18Cr in sulfidation resistance).
- VS. Extruded Fins: Solid welded fins offer stronger bonding under thermal stress.
- VS. Carbon Steel Fins: Longer lifespan in corrosive/oxidizing conditions.
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