What is a Seamless Incoloy 800 Tube?
ASeamless Incoloy 800 Tube (UNS N08800) is a high-temperature nickel-iron-chromium alloy tube manufactured from a solid billet through a seamless hot or cold forming process. Because the tube is produced without longitudinal weld seams, it provides superior structural integrity, pressure resistance, and leak-free performance compared with welded tubing.
Incoloy 800 alloy is specifically engineered for applications requiring excellent resistance to oxidation, carburization, and nitriding in elevated-temperature environments.
For high-temperature structural service, two enhanced grades are widely used:
- Incoloy 800H (UNS N08810) – optimized carbon content and grain structure for improved creep rupture strength
- Incoloy 800HT (UNS N08811) – further controlled chemistry and grain size for maximum creep and stress rupture resistance above 600°C (1100°F)
These alloys are widely used in heat exchangers, furnace components, petrochemical processing equipment, and power generation systems.
Key Features of Seamless Incoloy 800 / 800H / 800HT Tubes
Excellent High-Temperature Corrosion Resistance
The high nickel (Ni) and chromium (Cr) content provides strong resistance to oxidizing and reducing atmospheres, making the alloy suitable for demanding thermal environments.
Outstanding Thermal Stability
Incoloy 800 series alloys maintain mechanical strength and metallurgical stability during prolonged exposure to temperatures up to 1100°C (2012°F), while minimizing sigma phase embrittlement.
High Pressure Capability
Theseamless manufacturing process ensures uniform wall structure, enabling compliance with ASME and ASTM pressure vessel standards, and allowing the tubing to withstand higher internal pressure compared to welded alternatives.
Good Fabrication and Weldability
Seamless Incoloy 800 tubes can be welded using common industrial processes including:
- GTAW (TIG welding)
- GMAW (MIG welding)
They also exhibit good formability and machinability for fabrication of complex components.
Technical Specifications
Manufacturing Standards
Typical international standards for Seamless Incoloy 800 / 800H / 800HT Tubesinclude:
- ASTM B407 – Seamless Nickel-Iron-Chromium Alloy Tube
- ASME SB407
- EN / DIN equivalent specifications
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Seamless Incoloy 800 Tube.
The composition of Incoloy 800 is balanced to provide a blend of corrosion resistance and high-temperature strength.
Incoloy 800 is designed to maintain its strength and shape in high-stress, high-temperature applications.
These physical properties highlight the material’s ability to perform reliably under extreme thermal conditions.
Cold-Finished Pipes and Tubes:
| Specified/Calculated Nominal OD (Inches) | Permissible Variation (Inches) | Specified/Calculated Nominal OD (mm) | Permissible Variation (mm) |
| 0.500 to 5⁄8, excl. | ±0.005 | 12.7 to 15.8, excl. | ±0.127 |
| 5⁄8 to 1 1⁄2, incl. | ±0.0075 | 15.8 to 38.1, incl. | ±0.190 |
| Over 1 1⁄2 to 3 1⁄2, incl. | ±0.010 | Over 38.1 to 88.9, incl. | ±0.254 |
| Over 3 1⁄2 to 4 1⁄2, incl. | ±0.015 | Over 88.9 to 114.3, incl. | ±0.381 |
| Over 4 1⁄2 to 6, incl. | ±0.020 | Over 114.3 to 152.4, incl. | ±0.508 |
| Over 6 to 6 5⁄8, incl. | ±0.025 | Over 152.4 to 168.3, incl. | ±0.635 |
| Specified/Calculated Nominal OD (Inches) | Permissible Variation (Inches) | Specified/Calculated Nominal OD (mm) | Permissible Variation (mm) |
| 2 1⁄2 to 5 1⁄2, excl. | ±0.031 | 63.5 to 139.7, excl. | ±0.787 |
| 5 1⁄2 to 9 1⁄4, incl. | ±0.047 | 139.7 to 234.9, incl. | ±1.19 |
| Condition | Specified/Calculated Nominal OD (Inches) | Permissible Variation (Wall Thickness) |
| Cold-Finished | 0.500 to 5⁄8, excl. | ±15.0% |
| 5⁄8 to 4 1⁄2, incl. | ±10.0% | |
| Over 4 1⁄2 to 6 5⁄8, incl. | ±12.5% | |
| Hot-Finished | 2 1⁄2 to 9 1⁄4, incl. | ±12.5% |
Industrial Applications
Due to their excellent high-temperature strength and corrosion resistance, Seamless Incoloy 800 series tubes are widely used in the following industries:
Petrochemical & Chemical Processing
- Heat exchanger tubing
- Furnace pigtails
- Process piping systems
Power Generation
- Superheater tubes
- Reheater tubes
- Nuclear and fossil fuel power plant components
Thermal Processing Equipment
- Furnace retorts
- Radiant tubes
- Industrial muffles
Aerospace and Defense
- High-temperature exhaust systems
- Structural components exposed to extreme heat
Quality Assurance and Testing
AllSeamless Incoloy 800 / 800H / 800HT Tubes undergo strict inspection procedures to ensure compliance with international quality standards.
Typical inspection and testing include:
Material Test Certification
- EN 10204 3.1 / 3.2 certificates
Non-Destructive Testing (NDT)
- Ultrasonic Testing (UT)
- Eddy Current Testing (ET)
- Hydrostatic Pressure Testing
Positive Material Identification (PMI)
100% alloy composition verification using spectrometric analysis.
Mechanical Testing
- Impact testing
- Flattening test
- Flare test
- Grain size examination
These quality control procedures ensure reliable performance in high-temperature and high-pressure industrial environments.
