ASTM A269 TP321 High-Frequency Welded Finned Tubes for Waste Heat Recovery Equipment Product Overview ASTM A269 TP321 High-Frequency Welded Finned Tubes for Waste Heat Recovery Equipment are engineered heat-transfer components designed to increase effective heat-transfer surface area and support efficient thermal energy recovery in industrial process systems. Manufactured with TP321 titanium-stabilized austenitic stainless steel base tubes, these finned tubes combine the