What Is a Seamless Incoloy 800 Tube?
Seamless Incoloy 800 Tube — UNS N08800 — is a nickel–iron–chromium alloy (about 32% Fe, 21% Cr, 32% Ni) seamless tube produced to ASTM B407 from a solid billet with no weld seam, giving uniform structure and dependable pressure integrity.
The high iron content makes Alloy 800 significantly more economical than high-nickel alloys, while the chromium gives strong resistance to oxidation and carburization. ASTM B407 rates N08800 for service up to 1100 °F (593 °C), and the alloy keeps excellent chloride stress-corrosion-cracking resistance, which is why it has been the workhorse of process heating and heat-transfer equipment for decades.
Size Range: OD 6–257 mm · WT 0.5–35 mm
Key Features and Advantages
Seamless UNS N08800 tube offers a proven balance of economy, corrosion resistance and temperature capability:
Excellent Oxidation and Carburization Resistance: the 19.0–23.0% Cr and tightly controlled chemistry resist scaling and carburization in cyclic furnace atmospheres.
Chloride Stress Corrosion Cracking Resistance: the nickel–iron matrix outperforms austenitic stainless grades in hot chloride-bearing water and process streams.
Economical Nickel–Iron–Chromium System: about 39.5% minimum iron lowers alloy cost versus high-nickel alloys while retaining the key corrosion performance.
Good High-Temperature Strength: rated for service up to 593 °C (1100 °F) per ASTM B407 with stable, predictable behavior.
Proven Manufacturing Record: decades of use in fired heaters, exchangers and steam systems with established fabrication and welding practice.
Product Specifications and Data
To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for UNS N08800 seamless tube.
Equivalent Grade
| UNS | Common grade name | EN material number | EN steel name | JIS grade | GB/T grade |
|---|---|---|---|---|---|
| N08800 | Incoloy 800 | 1.4876 | X10NiCrAlTi32-21 | NCF800 | NS1101 / NS111 (legacy) |
Grade correspondence does not make ASTM, ASME, EN, JIS and GB delivery requirements interchangeable. Confirm chemistry, heat treatment, mechanical properties, dimensions, testing and certification against the purchase specification. Approximate or unconfirmed correspondences retain their qualification. See the grade designation index.
Chemical Composition
the nickel–iron–chromium balance of this family delivers the property mix.
| Grade | C | Mn | Si | P | S | Cu | Ni | Cr | Al | Ti | Fe | Others |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UNS N08800 | ≤0.10 | ≤1.50 | ≤1.00 | ≤0.045 | ≤0.015 | ≤0.75 | 30.0–35.0 | 19.0–23.0 | 0.15–0.60 | 0.15–0.60 | 39.5 min | – |
| UNS N08810 | 0.05–0.10 | ≤1.50 | ≤1.00 | ≤0.045 | ≤0.015 | ≤0.75 | 30.0–35.0 | 19.0–23.0 | 0.15–0.60 | 0.15–0.60 | 39.5 min | – |
| UNS N08811 | 0.06–0.10 | ≤1.50 | ≤1.00 | ≤0.045 | ≤0.015 | ≤0.75 | 30.0–35.0 | 19.0–23.0 | 0.25–0.60 | 0.25–0.60 | 39.5 min | Al+Ti 0.85–1.20 |
Chemical requirements per ASTM B407-22, Table 1 (composition limits, %). Single values are maximum content unless a range or minimum is indicated. Iron is determined arithmetically by difference (39.5% minimum). For Alloy 800HT (UNS N08811) the standard additionally requires Al + Ti = 0.85–1.20%. ASTM B407 supplies N08800 in the cold-worked annealed or hot-finished annealed condition.
Typical Mechanical Properties
Values below are specification minimums for the delivery condition; they define the acceptance basis for UNS N08800 seamless tube.
| Alloy & Condition | Yield Strength, min, ksi (MPa) | Tensile Strength, min, ksi (MPa) | Elongation in 2 in. or 50 mm, min, % |
|---|---|---|---|
| UNS N08800, cold-worked annealed | 30 (205) | 75 (520) | 30 |
| UNS N08800, hot-finished annealed | 25 (170) | 65 (450) | 30 |
| UNS N08810 / N08811, hot-finished annealed or cold-worked annealed | 25 (170) | 65 (450) | 30 |
Mechanical properties per ASTM B407-22, Table 2. Annealed UNS N08810 and N08811 shall conform to an average grain size of ASTM No. 5 or coarser (7.2). For small-diameter, light-wall N08800 tube (converter sizes), Table X3.1 applies: annealed tensile 75–100 ksi (520–690 MPa), yield 30 ksi (205 MPa), elongation 30%.
Typical Physical Properties
These physical properties highlight the material’s ability to perform reliably across a range of environments.
| Density | Melting Range | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 7.94 g/cm3 | 1350 – 1400 °C | 14.4 μm/m·°C (20–100°C) | 11.5 W/m·K | 196 GPa | 0.99 μΩ·m (20°C) |
Size Tolerance Chart (mm)
Permissible variations for seamless nickel alloy tube in accordance with ASTM B407-22, Table 3:
| Nominal Outside Diameter, mm | Permissible Variation in OD, mm | Average Wall, % | Minimum Wall |
|---|---|---|---|
| 12.7 to 15.8, excl | ±0.127 | ±15 | +28.5% / −0 |
| 15.8 to 38.1, incl | ±0.190 | ±10 | +28.5% / −0 |
| 38.1 to 88.9, incl | ±0.254 | ±10 | +28.5% / −0 |
| 88.9 to 114.3, incl | ±0.381 | ±10 | +28.5% / −0 |
| 114.3 to 152.4, incl | ±0.508 | ±12.5 | +28.5% / −0 |
| 152.4 to 168.3, incl | ±0.635 | ±12.5 | +28.5% / −0 |
| Hot-finished: 63.5 to 139.7, excl | ±0.787 | ±12.5 | +28.5% / −0 |
| Hot-finished: 139.7 to 234.9, incl | ±1.19 | ±12.5 | +28.5% / −0 |
Notes (ASTM B407-22, Table 3): tolerances apply to individual measurements and include ovality. For cold-finished tube, wall variation in any cross section (eccentricity) shall not exceed ±10% of the actual average wall. If minimum wall is ordered, the tolerance is +28.5% / −0. When tube is specified by OD and average wall, ordering to minimum wall is subject to agreement between manufacturer and purchaser.
Length Tolerance
- Cut lengths shall not be less than the specified length; a variation of +3.2 mm (cold-worked) or +4.8 mm (hot-finished) is permitted (ASTM B407-22, 8.2).
- For lengths over 9.1 m (30 ft), a variation of +6.4 mm is permitted.
- Tube is normally supplied in mill lengths or specific cut lengths as agreed in the order.
Disclaimer: Dimensional data above are summarized from ASTM B407-22, Table 3. The full and most current specification document must always be consulted for official design and procurement purposes.
Common Industrial Applications
The combination of corrosion resistance, mechanical strength and manufacturing quality makes UNS N08800 seamless tube a preferred choice for:
Process Heating and Heat Exchangers
Fired-heater tubes, exchanger tubing and process lines in hydrocarbon and chemical plants.
Steam Generation and Power
Superheater and boiler-adjacent tubing where chloride SCC excludes 300-series grades.
Petrochemical and Refining
Transfer lines, reboilers and cooling service in refineries and petrochemical units.
Food Processing and General Industry
Equipment tubing requiring clean, corrosion-resistant surfaces with long service life.
Frequently Asked Questions
What sizes are available for Incoloy 800 seamless tube?
Continuous supply covers OD 6–257 mm and WT 0.5–35 mm. Requirements outside this range are reviewed against mill capability on request.
Which specification governs Incoloy 800 seamless tube?
ASTM B407 / ASME SB407 is the governing seamless specification for Incoloy 800 tube; the edition in force at order time is stated on the quotation and purchase order.
What inspection documents are provided?
Each order is documented with a mill test certificate stating heat chemistry and mechanical test results. EN 10204 3.1 certification, hydrostatic testing, eddy-current or ultrasonic inspection and PMI are performed when specified in the purchase order.
Technical review: page data reviewed by the Xinzhe technical desk on 2026-09-27. Property values are typical reference data compiled from Special Metals Corporation alloy data sheets and the governing ASTM specifications; they are not acceptance guarantees unless stated in the purchase order. “Incoloy” is a trademark of Special Metals Corporation, used here to identify the alloy family only.
Ready to Request a Quotation?
Send the NPS and schedule (or actual OD and wall), quantity, length, end finish and the inspection items you need as acceptance criteria — you will get a written quotation stating the specification and edition, delivery condition, documents included and lead time.
