Alloy 309S Stainless Steel Seamless Pipe Heat Resistant SS Pipe Diameter 89mm 114mm 168mm 219mm

1. Core Specifications & Dimensions

2. Key Performance Characteristics

2.1 Heat Resistance (Primary Advantage)

• Continuous Service Temperature: Up to 1040°C (1904°F) (ideal for long-term exposure to high heat, e.g., furnace flues).
• Short-Term Peak Temperature: Withstands up to 1150°C (2102°F) (suitable for intermittent high-heat processes).
• Oxidation Resistance: The high Cr-Ni content forms a dense, adherent chromium oxide (Cr₂O₃) film on the surface, preventing scaling and oxidation even in cyclic heating/cooling.

2.2 Mechanical Properties

2.3 Corrosion Resistance

• Resists oxidizing environments (e.g., air, steam, and nitric acid solutions).
• Performs well in mild reducing environments (e.g., dilute sulfuric acid at low temperatures).
• Superior to standard 304 stainless steel in high-temperature corrosion (e.g., against sulfur-bearing gases in petrochemical plants).

3. Production Process of Seamless Pipes

1. Raw Material Preparation: Use 309S stainless steel billets (chemical composition verified via 光谱分析 /spectroscopic analysis).
2. Hot Piercing: Heat billets to 1200°C–1250°C, then push them through a piercing mill to create a hollow "mother tube" (mandrel mill process).
3. Hot Rolling/Extrusion: Reduce the mother tube’s diameter and wall thickness to the target size (e.g., 89mm OD) using a continuous rolling mill, ensuring uniform dimensions.
4. Annealing: Heat the pipe to 1050°C–1100°C and cool rapidly (water quenching) to soften the material, restore ductility, and eliminate internal stresses.
5. Pickling & Passivation: Immerse in nitric acid solution to remove surface oxides and form a passive chromium oxide film (enhances corrosion resistance).
6. Precision Sizing & Cutting: Use cold drawing (for tight tolerance) if needed, then cut to standard lengths (6m/12m) and inspect for dimensional accuracy.
7. Quality Testing: Conduct non-destructive testing (NDT) such as ultrasonic testing (for internal defects) and hydrostatic testing (for pressure resistance), plus chemical composition and mechanical property verification.

4. Compliance Standards

5. Competitive Advantages

• Superior High-Temp Stability: Outperforms 304 (max 870°C) and 316 (max 815°C) in continuous high-temperature service, making it the top choice for heat-intensive applications.
• Seamless Reliability: No welded joints reduce the risk of leakage or rupture under high pressure (up to 10 MPa for 219mm OD pipes) or thermal cycling.
• Low Carbon Advantage: The ≤0.08% C content prevents "sensitization" (carbide precipitation at grain boundaries) during welding or high-temperature use, avoiding intergranular corrosion.
• Dimensional Versatility: The 89mm–219mm OD range covers diverse needs—from small-scale industrial heaters (89mm) to large boiler tubes (219mm).

6. Equivalent Grades

7. Applications

• Thermal Processing Equipment: Furnace flues, heat exchanger tubes, and boiler tubes (89mm/114mm for small furnaces; 168mm/219mm for industrial boilers).
• Petrochemical Industry: Pipes for catalytic crackers, reformers, and sulfur recovery units (resists sulfur-bearing gases at high temps).
• Power Generation: Steam pipelines in coal-fired or gas-fired power plants (withstands high-pressure steam at 500°C–600°C).
• Metallurgical Industry: Annealing furnace components, molten metal transfer lines, and incinerator exhaust systems.
• Chemical Processing: Pipes for handling nitric acid, organic acids, and high-temperature chemical reactors.