ASTM A179 High-Frequency Welded Finned Tubes for HRSG

Product Overview

ASTM A179 High-Frequency Welded Finned Tubes are low-carbon steel finned tubes designed for efficient heat recovery in Heat Recovery Steam Generator (HRSG) systems. The base tubes are manufactured from ASTM A179 seamless cold-drawn low-carbon steel, while the fins are continuously welded to the tube surface using a high-frequency electrical resistance welding process.

The high-frequency welding process creates a strong and continuous metallurgical bond between the fin and tube, providing reliable heat transfer performance and good mechanical stability during long-term operation. Compared with bare tubes, the increased external surface area of the fins allows more heat to be transferred within a compact heat exchanger arrangement.

ASTM A179 is specified for seamless cold-drawn low-carbon steel heat-exchanger and condenser tubes and is particularly suited to heat-transfer applications where good thermal conductivity, formability, and economical material selection are important.

For HRSG applications, ASTM A179 high-frequency welded finned tubes are primarily considered for suitable lower- or moderate-temperature heat recovery sections rather than the highest-temperature superheater or reheater sections. The actual material selection should be determined according to the HRSG design temperature, pressure, corrosion environment, applicable code, and project specifications.

Common Applications in HRSG Systems

ASTM A179 high-frequency welded finned tubes can be considered for suitable heat recovery sections where the operating conditions are compatible with low-carbon steel.

Typical applications include:

• HRSG economizer sections
• Feedwater preheaters
• Low-temperature heat recovery sections
• Gas-side heat recovery banks
• Heat recovery heat exchangers
• Waste heat recovery equipment
• Water preheating systems
• Industrial exhaust-gas heat recovery units
• Other tubular heat-transfer equipment operating within the applicable material limits

For high-temperature HRSG components such as superheaters and reheaters, alloy steel grades such as P11, P22, P91, or other project-specified materials may be required instead of ASTM A179.

Chemical Composition of ASTM A179

ASTM A179 is a low-carbon steel grade. Its chemical composition is controlled primarily through carbon, manganese, phosphorus, and sulfur. The ASTM A179 specification requires carbon of 0.06–0.18%, manganese of 0.27–0.63%, phosphorus and sulfur each at a maximum of 0.035%.

Mechanical Properties of ASTM A179

ASTM A179 requires the material to meet specified mechanical properties appropriate for its intended heat-exchanger and condenser tube applications. Typical minimum requirements include a tensile strength of 47 ksi (approximately 325 MPa), yield strength of 26 ksi (approximately 180 MPa), and minimum elongation of 35%. The maximum hardness requirement is 72 HRB.