ASTM A213 TP321 TP347 Stainless Steel Heat Exchanger Tube

ASTM A213 / ASME SA213 specification covers seamless ferritic and austenitic steel boiler, superheater and heat exchanger tubes.

TP321 stainless steel is a material with excellent high temperature Stress Rupture properties and high temperature Creep Resistance stress mechanical properties are better than 304 stainless steel. 321 stainless steel has good corrosion resistance in the atmosphere and is widely used in petrochemical, electric power, bridge and automobile industries.

Austenitic stainless steel equivalent to domestic grade 0Cr18Ni10Ti 321 stainless steel is Ni-Cr-Mo austenitic stainless steel, its performance is very similar to 304, but due to the addition of titanium metal, so that it has better resistance to grain boundary corrosion and high temperature strength. Due to the addition of titanium metal, it effectively controls the formation of chromium carbide.

TP321 austenitic stainless steel has good corrosion resistance in the atmosphere and is widely used in petrochemical, electric power, bridge and automobile industries . However, the "stainless steel" is not absolute, due to the special service environment, stainless steel will also corrosion. Medium concentration, pH value, temperature and other factors will have a greater impact on the corrosion resistance of stainless steel. For example, in the sensitization temperature range of 450~850℃ for a long time, stainless steel will occur intergranular corrosion. The mechanism is that C combines with Cr at the grain boundary to form Cr23C6 and precipitates, so that the Cr content at the grain boundary is reduced, which is the so-called "chromium poor". The Cr element is one of the main elements to inhibit intergranular corrosion, when the Cr content at the grain boundary is less than 12%, the probability of intergranular corrosion will be increased.

ASTM A213 TP347 stainless steel heat exchanger tube has top-level intergranular corrosion resistance, excellent welding condition, high reliability in sensitized environments such as welding heat affected zone, excellent high temperature strength, high temperature oxidation resistance and resistance to multiple corrosion, can adapt to harsh combustion and chemical environments, and is an irreplaceable material in the high temperature section.

However, it should be noted during use that the cost of ASTM A213 TP347 is significantly higher than that of ferritic alloy steels such as T5 and T9, and the thermal expansion coefficient is higher, which will produce higher thermal stress and thermal fatigue sensitivity. At the same time, the thermal conductivity is low and the thermal conductivity is poor. It should avoid aqueous solutions or steam environments containing chloride ions to reduce the risk of chloride stress corrosion cracking. The welding process must be strictly controlled during welding to reduce the tendency of thermal cracking.

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.

ASTM A213 TP321 TP347 Stainless Steel Heat Exchanger Tube Industry application

1. Oil exhaust gas combustion pipeline
2. Engine exhaust tube
3. Boiler shell, heat exchanger, heating furnace parts
4. Diesel engine muffler parts
5. Boiler pressure vessel
6. Chemical trucks
7. Expansion joints
8. Spiral welded tube for furnace tube and dryer

ASTM A213 TP321 TP347 Stainless Steel  Seamless Heat Exchanger Tube

 

 

 

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