How to Select the Right Flange Material for High-Temperature Service (Complete 2025 Guide)

High temperature can cause:

• Loss of strength
• Thermal expansion
• Oxidation & scaling
• Creep (slow permanent deformation)
• Gasket leakage
• Bolt loosening
• Fatigue cracking

Choosing the wrong material guarantees failure. Choosing the right one ensures years of safe performance.

Best for Steam, High Temperature & Pressure

Typical Grades:

• ASTM A182 F1 (up to ~500°C)
• ASTM A182 F5 (up to ~550°C)
• ASTM A182 F9 (up to ~600°C)
• ASTM A182 F11 (up to ~600°C)
• ASTM A182 F22 (up to ~625°C)
• ASTM A182 F91 (up to ~650°C)

Why Alloy Steel is Ideal

• Excellent strength at high temperature
• Great resistance to creep
• Handles pressure + temperature together
• Standard choice in power plants

Best For:

• Steam lines
• Boiler piping
• High-temperature chemical lines
• Turbines
• Turbines
• Heat exchangers

Best for Corrosion + Medium–High Temperature

Common Grades: SS 304 / 304L, 316 / 316L, 321, 347

Temperature Limits:

• SS 304/316 → ~425–870°C
• SS 321 → ~870°C
• SS 347 → ~870°C

Why Stainless Steel Works

• Great for corrosion + moderate to high temp
• No scaling at high temperature
• SS 321 & SS 347 ideal for thermal cycling

Best For:

• Heat exchangers
• Chemical processing
• Food & pharma reactors
• Steam condensate systems

Extreme Temperature + Extreme Corrosion

Popular Grades:

• Inconel 600 (up to 1175°C)
• Inconel 625 (up to 980°C)
• Inconel 800 / 800H / 800HT (up to 1100°C)
• Inconel 825
• Hastelloy C276
• Monel 400 / K500

Why Nickel Alloys Are the Best

• Highest temperature resistance
• Best oxidation resistance
• Unmatched corrosion resistance
• No creep, no cracking

Best For:

• Furnaces
• Heat-treat lines
• High-temp chemicals
• Acidic & corrosive media
• Offshore high-temp use

Not for High Temp – But Important Note

• A105 flanges → max 425°C only

Only suitable for low to medium temperature. Above 425°C → cracking risk.

• Steam → Alloy Steel F11 / F22 / F91
• Hydrocarbon → SS 316 / Inconel 825
• High-Chloride → Duplex / Super Duplex
• High Temperature + Corrosion → Inconel 600 / 800
• Acidic Media → Hastelloy C276
• Seawater → Monel 400 / Duplex
• Thermal Cycling → SS 321 / SS 347

• Power Plants → Alloy Steel F22 / F91
• Refineries → SS 316L / Inconel 825
• Petrochemicals → Alloy Steel F11 / Nickel Alloys
• Fertilizer → SS 316L / Alloy Steel
• Offshore → Super Duplex / Inconel

• Alloy Steel → Spiral Wound Gasket
• Stainless Steel → Graphite Gasket
• Inconel → Metal Jacketed / RTJ Gasket

Using the wrong gasket leads to high-temperature leakage.

Choosing the right flange material for high-temperature service is crucial for safety, zero leakage, long service life, pressure stability, and corrosion resistance.

Use this simple formula:

• Temperature High → Alloy Steel
• Temperature + Corrosion High → Nickel Alloys
• Corrosion High → Stainless Steel or Duplex
• Low Temperature → Carbon Steel

Moksh Tubes supplies high-temperature flanges with complete testing and certification for reliable, long-term industrial performance.