ASTM A312 TP304H Serrated Fin Tube for Boiler and Air Heater

ASTM A312 TP304H Serrated Fin Tube advantages

• High heat exchange efficiency: The serrated structure breaks the laminar boundary layer of the fluid flowing through the fin surface, forcing the fluid to transition from laminar flow to turbulent flow. Turbulent flow enhances the convective heat transfer coefficient, which is 30%–50% higher than that of ordinary straight fin tubes. Meanwhile, the fins expand the heat transfer area by 3–8 times compared with smooth tubes.
• Anti-fouling & easy cleaning: The serrated gaps disrupt the deposition of dust, scale, and other impurities on the fin surface, reducing fouling thermal resistance. During maintenance, high-pressure water washing or air blowing can easily remove accumulated dirt.
• Corrosion & high-temperature resistance: TP304H material is resistant to atmospheric corrosion, mild acid/alkali corrosion, and high-temperature oxidation, suitable for harsh working conditions such as flue gas waste heat recovery and chemical fluid heat exchange.
• Structural compactness: High heat exchange efficiency reduces the number of tubes required for the heat exchanger, miniaturizing the equipment volume and saving installation space and manufacturing costs.
• Long service life: High-frequency welding ensures the fin-base tube joint strength is equivalent to the base tube material, avoiding fin falling off caused by thermal cycling; the material's fatigue resistance is also better than ordinary carbon steel fin tubes.

ASTM A312 TP304H Serrated Fin Tube Applications

These tubes are used in high-duty, high-temperature heat recovery and heat transfer equipment:

1. Heat Recovery Steam Generators (HRSGs): In the economizer, evaporator, and superheater sections where recovering energy from hot turbine exhaust gas is critical.
2. Power Plant Boilers: Especially in the economizer section to pre-heat feedwater using hot flue gases, improving overall plant efficiency.
3. Waste Heat Recovery Units: In chemical, petrochemical, and metallurgical industries to capture heat from process exhaust streams.
4. Air Heaters: For pre-heating combustion air in industrial boilers and furnaces.

Working Principle of Heat Transfer Enhancement

• The heat transfer principle of serrated fin tubes is based on dual enhancement of heat transfer area and heat transfer coefficient:
• Area expansion: The fins extend the heat transfer surface of the base tube, increasing the contact area between the tube wall and the fluid (e.g., air, flue gas), which is the basic way to enhance heat transfer.
• Turbulence enhancement: When the fluid flows through the serrated fins, the flow direction and speed change continuously at the serrated gaps, destroying the low-heat-transfer-efficiency laminar boundary layer on the fin surface. Turbulent flow increases the mixing intensity of fluid molecules, accelerating the heat transfer between the fluid and the tube wall.
• Material matching: TP304H's high-temperature stability ensures that the tube wall does not deform or fail during high-temperature heat transfer, maintaining long-term heat transfer efficiency.

ASTM A312 TP304H Serrated Fin Tube Application

ASTM A312 TP304H serrated fin tubes are ideal for high-temperature, low-heat-transfer-coefficient fluid heat exchange systems, and their main applications include:

• Power industry: Air preheaters, economizers, and waste heat boilers of thermal power plants; heat exchange components of biomass power generation boilers.
• Petrochemical industry: Heat exchangers for high-temperature reaction kettles; waste heat recovery systems for flue gas in refineries; heat transfer tubes for steam generators.
• Metallurgical industry: Waste heat recovery of blast furnace flue gas; heat exchange systems for steel rolling mill cooling water.
• HVAC & refrigeration: Condensers and evaporators of large central air conditioners; heat recovery ventilators (HRVs) for industrial buildings.
• New energy field: Heat collection tube components of solar thermal power generation systems; heat exchangers for geothermal energy utilization.

ASTM A312 TP304H Serrated Fin Tube FAQ
Q1: What is the difference between TP304 and TP304H?

A: The core difference lies in carbon content and application scenarios:

TP304 carbon content: ≤ 0.08%, suitable for room-temperature or low-temperature corrosion-resistant environments.
TP304H carbon content: 0.04%–0.10%, higher carbon content improves high-temperature creep resistance, suitable for long-term operation above 500℃.
Note: TP304H has slightly lower room-temperature corrosion resistance than TP304, but better high-temperature performance.

Q2: What is the maximum operating temperature of TP304H serrated fin tubes?

A: The continuous safe operating temperature is up to 870℃; short-term (within 100 hours) peak temperature can reach 925℃. Beyond this range, the material's oxidation rate accelerates, reducing service life.

Q3: How to choose fin height and density?

A: The selection depends on the heat exchange medium and working conditions:

For low-viscosity, clean fluids (e.g., air): Choose high fin density (15–20 fpi) and medium fin height (15–20 mm) to maximize heat exchange area.
For high-dust, high-viscosity fluids (e.g., flue gas): Choose low fin density (10–12 fpi) and high fin height (20–25 mm) to reduce fouling and facilitate cleaning.

Q4: Can the fin tube be customized for special corrosion environments?

A: Yes. For strong corrosive environments (e.g., chloride-containing media, strong acids), TP304H can be replaced with higher-grade materials such as TP316H or TP321H. The fin surface can also be coated with anti-corrosion coatings (e.g., fluoropolymer coatings) as required.

Q5: What non-destructive testing methods are used for fin tubes?

A: Key testing items include:

Eddy current testing: Detecting cracks or gaps in the fin-base tube welding joint.
Hydrostatic testing: Testing the pressure resistance of the base tube, with test pressure 1.5 times the design pressure.
Visual inspection: Checking fin shape, spacing uniformity, and surface defects.