ASTM A376 TP347H HFW Solid Finned Tube with Carbon Steel Fins For Refinery Heaters

ASTM A376 TP347H HFW (High-Frequency Welded) solid finned tubes with carbon steel fins are specialized components used in high-temperature applications, such as heat exchangers, boilers, and superheaters. Here’s a breakdown of the key aspects:

1. Base Tube Material: ASTM A376 TP347H

(1). Chemical Composition (Weight %)

The composition of ASTM A376 TP347H follows the standard requirements for austenitic stainless steel with niobium (Nb) stabilization to prevent carbide precipitation and improve high-temperature strength.

Notes:

The "H" grade (TP347H) has a controlled carbon content (0.04–0.10%) for improved high-temperature creep resistance.

Niobium (Nb) binds with carbon to prevent chromium carbide formation (sensitization) in welded structures.

(2). Mechanical Properties (Room Temperature)

Per ASTM A376, the mechanical properties of TP347H are as follows:

High-Temperature Properties (Creep & Stress Rupture):

• Designed for service up to 760°C (1400°F).Excellent creep strength due to Nb stabilization.
• Stress rupture data is typically provided in ASME Boiler & Pressure Vessel Code, Section II, Part D.

(3). Heat Treatment

Solution Annealing: Typically heated to 1038–1121°C (1900–2050°F) followed by rapid cooling (water quenching or air cooling) to maintain corrosion resistance.

2. HFW (High-Frequency Welded) Construction

The tube is longitudinally welded using high-frequency induction or resistance welding, ensuring a strong, consistent seam.

Suitable for high-pressure applications due to the integrity of the weld.

3. Solid Finned Tube Design

Fins: Typically helical (spiral) fins welded or embedded onto the outer surface of the tube.

Purpose: Increases heat transfer efficiency by expanding the surface area.

4. Carbon Steel Fins

Material: Usually low-carbon or medium-carbon steel (e.g., ASTM A179/A192 or similar).

Why Carbon Steel?

• Cost-effective compared to stainless steel fins.
• Adequate for moderate-temperature zones where oxidation/corrosion is not severe.
• Good thermal conductivity.

Limitation: Less resistant to high-temperature oxidation and corrosion compared to stainless steel. May require protective coatings in harsh environments.

Primary Applications of ASTM A376 TP347H HFW Solid Finned Tube with Carbon Steel Fins

1. Power Generation (Boilers & Superheaters)

• Superheater & Reheater Tubes
• TP347H’s high creep resistance (due to Nb stabilization) allows it to withstand steam temperatures up to 760°C (1400°F).
• Carbon steel fins provide cost-effective extended surface area for improved heat absorption from flue gases.
• Heat Recovery Steam Generators (HRSGs)
• Used in waste heat recovery from gas turbine exhaust.

2. Petrochemical & Refinery Heaters

• Fired Heaters & Cracking Furnaces
• Resists sulfidation and oxidation in refinery process heaters.
• Carbon steel fins are acceptable in zones where corrosion is moderate (otherwise, stainless steel fins may be needed).

3. Waste Heat Recovery Systems

• Air Preheaters & Economizers
• Recovers heat from exhaust gases in cement plants, steel mills, and chemical processing.
• The HFW construction ensures leak-proof performance under pressure.

4. Industrial Boilers & Process Heaters

• High-Pressure Steam Boilers
• TP347H base tube handles high-pressure steam, while carbon steel fins optimize heat transfer efficiency.