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