ASTM A213 / ASME SA213 TP347 Stainless Steel Seamless Heat Exchanger Tube

ASTM A213 / ASME SA213 TP347 Stainless Steel Seamless Heat Exchanger Tube

ASTM A213 / ASME SA213 specification covers seamless ferritic and austenitic steel boiler, superheater and heat exchanger tubes. TP347 is an important material under this standard and is commonly used in heat transfer equipment such as boilers, reheaters, superheaters and heat exchangers.

ASTM A213 /ASME SA213 TP347 heat exchanger tube is an austenitic stainless steel with a face-centered cubic structure. It is usually non-magnetic and may have weak magnetism after cold working. It can be used in high temperature environments and has excellent oxidation resistance, toughness, formability and weldability.

Chemical Composition of TP347 Stainless Steel Heat Exchanger Tube Boiler Tube

Among the main chemical components of TP347 heat exchanger tubes, Chromium provides TP347 with basic anti-oxidation and corrosion resistance; Nickel mainly plays a role in stabilizing austenite structure and improving high-temperature strength and corrosion resistance; Carbon content is the key to distinguishing TP347 from TP347H heat exchanger tubes, and the carbon content will affect the strength and intergranular corrosion resistance of the heat exchanger tube; Niobium is the core element of TP347 heat exchanger tubes. Niobium will chemically combine with carbon to form stable niobium carbide (NbC) and precipitate at the grain boundary earlier than chromium carbide. This component significantly improves the heat exchanger tube's resistance to intergranular corrosion, especially after welding or when the heat exchanger tube is in the sensitization temperature range of 425-860°C for a long time.

When choosing to use TP347 or TP347H heat exchange tubes, the decision is mainly based on the design temperature of the specific equipment and the life requirements of the heat exchange tubes. As mentioned above, the difference between TP347 and TP347H heat exchange tubes lies mainly in the carbon content. The upper limit of the carbon content of TP347 is 0.08%, and the "H" in TP347H stands for High Temperature. Its carbon content is usually 0.04% - 0.10%. The higher carbon content can make the heat exchange tube precipitate fine niobium carbide or carbon chromium compounds at higher temperatures, which can make the heat exchange tube have higher high temperature creep rupture strength. It is specially designed for heat exchange tubes used in high temperature environments for a long time.

Common corresponding grades of TP347
China: 0Cr18Ni11Nb (GB/T 20878, GB/T 5310) / 06Cr18Ni11Nb (new grade)
Europe: X6CrNiNb18-10 (EN 1.4550, EN 10216-5)
Japan: SUS 347 (JIS G3459)
Germany: X6CrNiNb18-10 (DIN 1.4550)
General: UNS S34700 (TP347), UNS S34709 (TP347H)

ASTM A213/ASME SA213 TP347 Application Scenarios

• Welded parts or parts that cannot be solution treated after welding: Because TP347H has strong anti-sensitization ability, unless there are special requirements or severe deformation, it is usually not necessary to perform solution annealing like 304 to restore corrosion resistance after welding.
• Equipment exposed to the sensitization temperature range (425-860°C) for a long time: such as some heat exchange equipment.
• Higher temperature areas requiring higher creep strength: TP347H is usually selected. For example, high-temperature superheaters and reheaters of modern ultra-supercritical (USC) power plant boilers.
• Environments exposed to certain specific corrosive media: such as nitric acid, organic acids, etc.