ASTM A213 TP347( UNS 34700) stainless steel tube is a high alloy austenitic stainless steel pipe, designed for high temperature, high pressure, and corrosion resistant

environment, widely used in energy, chemical, and petroleum fields.

1. Material properties of TP347

1.1 Chemical composition

Core components (typical values, unit: wt%):

Chromium (Cr): 17-19%

Provides oxidation resistance and corrosion resistance.

Nickel (Ni): 9-13%

Stabilizes austenite structure, enhances toughness and high temperature resistance.

Niobium (Nb): ≥10× carbon content

Combines with carbon to form stable niobium carbide (NbC), prevents the precipitation of chromium carbide and avoids intergranular corrosion.

Carbon (C): ≤0.08%

Control the carbon content to reduce the risk of sensitization.

Other elements: Manganese (Mn≤2%), Silicon (Si≤1%), Phosphorus (P≤0.045%), Sulfur (S≤0.03%).

1.2 Corrosion resistance

Anti-intergranular corrosion: The addition of niobium effectively prevents the precipitation of chromium carbide during welding or high temperature (450-850°C), and

avoids corrosion caused by chromium depletion at grain boundaries.

Oxidation resistance: In high-temperature oxidizing environments (such as boilers), a dense chromium oxide layer is formed on the surface, and the oxidation

resistance temperature can reach 870°C.

Acid resistance: It performs well in nitric acid, organic acids and weak alkaline media, but should be used with caution in strong reducing acids (such as hydrochloric acid).

2. Mechanical properties of ASTM A213 TP347

Tensile strength: ≥515 MPa

Yield strength: ≥205 MPa

Elongation: ≥35% (gauge length 50mm)

Hardness: ≤90 HRB (Rockwell hardness)

High temperature performance: maintains good creep resistance and endurance strength at 600-800°C.

3. Application areas of ASTM A213 TP347 tube

3.1 Power industry

Boiler tubes and superheater tubes: used for high-temperature and high-pressure steam pipelines in thermal power plants.

Heat exchangers: resistant to oxidation and thermal fatigue in high-temperature exhaust gas recovery systems.

3.2 Petrochemicals

Cracking furnace tubes: withstand high-temperature hydrocarbon media in ethylene cracking units.

Catalytic reforming equipment: resist corrosive environments containing sulfur and chloride ions.

3.3 Food and pharmaceuticals

Sanitary pipes: because there is no risk of sensitization corrosion, they meet FDA hygiene standards and are used to transport high-purity liquids.

3.4 Other fields

Nuclear power plants: corrosion-resistant pipes for secondary circuit systems.

Automobile exhaust system: high temperature exhaust gas corrosion resistance.

4. Manufacturing and standards of ASTM A213

4.1 Implementation standards

ASTM A213: Specification for seamless cold-drawn or hot-rolled austenitic steel pipes.

ASME SA213: Equivalent standard for boilers and pressure vessels.

Other standards:

EN 10216-5 (European standard)

JIS G3463 (Japanese standard)

GB/T 5310 (Chinese standard).

4.2 Production process

Hot rolling/cold drawing: Dimensional accuracy is controlled by hot rolling or cold drawing process.

Solution treatment: Rapid cooling (water quenching) after heating to 1040-1150°C to eliminate processing stress and homogenize the structure.

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