Application of ASTM A192 Serrated Finned Tube in Medium-to-Low Temperature Flue Gas Waste Heat Recovery (300–500°C)

The serrated finned tube with ASTM A192 seamless low-carbon steel as the base tube offers excellent high-temperature strength, weldability, and cost-effectiveness, making it a highly economical structural material suitable for medium-to-low temperature flue gas environments (300–450°C). It is widely used in waste heat recovery systems. The high-frequency resistance welding process ensures a metallurgical bond between the carbon steel serrated fins and the base tube, resulting in robust connections and superior resistance to thermal fatigue and vibration—enabling long-term, stable operation under industrial conditions involving dust, high temperatures, and frequent start-stop cycles.

The serrated fins feature periodic notches along their edges that disrupt the airflow boundary layer, inducing vortices and secondary flows. This significantly enhances the convective heat transfer coefficient on the flue gas side—improving it by 30–60%—and greatly boosts overall heat exchange efficiency. Compared to plain fins, it achieves higher heat recovery capacity within the same footprint; compared to stud tubes or integrally extruded fins, it offers lower cost and greater manufacturing flexibility, effectively balancing performance and economy.

In waste heat recovery projects, this type of finned tube is extensively applied in equipment such as low-temperature economizers in power plants, HRSGs (Heat Recovery Steam Generators), cement kiln boilers, and FCC (Fluid Catalytic Cracking) regenerator units. It effectively reduces flue gas exhaust temperature, improves energy utilization, and delivers substantial annual energy savings, typically with an investment payback period of less than three years. When combined with optimized design features—such as staggered tube arrangement, larger fin pitch to prevent fouling—as well as soot-blowing systems and material protection strategies (e.g., maintaining tube wall temperature above acid dew point), it ensures long service life while enabling efficient, safe, and sustainable heat recovery. As such, it has become the mainstream choice in the field of industrial energy conservation.

• Excellent Weldability: The surface oxide layer is easy to remove, enabling stable, concentrated energy fusion during high-frequency resistance welding—ensuring a reliable metallurgical bond between fins and base tube.
• Low Cost: Approximately 60–70% the price of alloy steels (e.g., T1/T11), offering significant economic benefits.
• Widely Recognized: Complies with ASME BPVC Section I and Section VIII, making it suitable for use in pressure equipment design.

For typical industrial flue gas environments with no severe corrosion and operating temperatures ≤450°C, ASTM A192 represents the optimal balance among performance, cost, and manufacturability, making it the preferred choice for base tubes in waste heat recovery systems.

Waste heat recovery systems operate continuously under harsh conditions—high temperatures, dusty environments, and frequent start-stop cycles. In such cases, reliability ("can it survive?") is more important than peak efficiency. The performance of ASTM A192 serrated finned tubes is evaluated across five key durability criteria:

• Use A192 in high-temperature sections, switch to ND steel or aluminized tubes in low-temperature zones.
• Reinforce fin root thickness → improves erosion resistance.
• Install support plates → reduces span length and suppresses vibration.
• Integrate acoustic soot-blowing systems → enables proactive cleaning and extends maintenance intervals.

With proper design and operational practices, these finned tubes can safely operate for 8–10 years in typical waste heat applications, achieving an MTBF (Mean Time Between Failures) exceeding 30,000 hours.

Compared to plain fins, serrated fins incorporate periodic notches along the edge, creating four key breakthroughs in heat transfer performance:

The serrated fin represents the ideal compromise for high-temperature flue gas waste heat recovery—delivering strong heat transfer, controllable costs, reliable lifespan, and feasible maintenance.