ASTM A213 TP321 Stainless Steel HF Welded Finned Solid Tubes for Heating Furnaces

ASTM A213 TP321 Stainless Steel HF Welded Finned Solid Tubes for Heating Furnaces

Chemical Composition (%) Maximum

Mechanical Properties

ASTM A213 TP321 (UNS S32100) is a seamless titanium-stabilized austenitic stainless steel tube designed for boilers, heat exchangers, and high-temperature applications. When used as the base tube for high-frequency (HF) welded solid finned tubes, it fully leverages the unique synergy between material properties and the HF welding manufacturing process.

Core Advantages of ASTM A213 TP321 Stainless Steel Tubes For HF Welded Finned Solid Tubes

ASTM A213 TP321 exhibits excellent resistance to sensitization and intergranular corrosion. TP321 contains titanium (Ti content ≥ 5 times the carbon content), which preferentially combines with carbon to form stable titanium carbide. Within a critical temperature range of 425–815 °C, TP321 effectively prevents the precipitation of chromium carbide, while conventional TP304 exhibits sensitization within this temperature range.

High-frequency welding introduces localized thermal cycling on the tube surface during finned connections. Unlike unstabilized steels, TP321 avoids weld corrosion in the heat-affected zone (HAZ) of the tube. No mandatory solution annealing is required after finned welding; this saves manufacturing costs while maintaining the excellent corrosion resistance required for long-term cyclic high-temperature service.

ASTM A213 TP321 exhibits superior high-temperature mechanical properties and creep resistance. It operates continuously at temperatures up to 870–900 °C and demonstrates excellent oxidation resistance in flue gas and high-temperature process gas environments. Under sustained high-temperature and high-pressure cycling, its creep rupture strength and thermal fatigue resistance are superior to TP304. This is crucial for finned tubes operating in applications with frequent thermal expansion and contraction, such as waste heat recovery systems, superheaters, and process heat exchangers; it reduces the risk of tube cracking under thermal stress.

TP321 exhibits good ductility and weldability; brittle intermetallic compounds are less likely to form at the fusion line between the fins and the base tube. It maintains the toughness of the base tube, preventing surface embrittlement and its propagation into fatigue cracks under vibration and thermal cycling.

Key Application

Boiler superheaters & flue gas waste heat recovery units

Process air coolers

Thermal oxidizer heat exchangers

Petrochemical furnace waste heat systems

Heat exchangers with cyclic temperature variation and no post-fin-weld heat treatment allowance