Detailed Product Description
Application & Compliance
The ASTM B407 UNS N08810 seamless tube is specified for shell and tube heat exchangers, pressure vessels, and furnace tubing that operate above 1100°F (593°C), where carbon steel and standard austenitic stainless steels no longer provide adequate creep and rupture resistance. In steam reforming and ethylene cracking furnaces, the tube carries process gas at metal temperatures where 304H and 316H would suffer premature creep failure; N08810's controlled carbon content of 0.05–0.10% and restricted grain size allow it to maintain strength under sustained thermal exposure. In high-temperature shell and tube heat exchangers handling hot corrosive gas, the tube provides the pressure boundary between the tube side and shell side fluids while resisting oxidation and carburization that degrade lower-alloy materials. When rolled or welded into a heat exchanger tubesheet, the tube forms a leak-tight joint that maintains integrity through repeated thermal cycling.
The tube is manufactured and tested in accordance with ASTM B407 / ASME SB407, the standard specification for nickel-iron-chromium alloy seamless pipe and tube, covering UNS N08810 in the cold-worked and hot-finished annealed condition. The alloy is normally employed above 1100°F (593°C) where creep and rupture resistance are required, and is annealed to develop a controlled grain size for optimum properties in this temperature range. Certification is available per EN 10204 Type 3.1. Third-party inspection by ABS, GL, DNV, NK, PED, AD2000, and CCS is available upon request.
Problem Solved
The N08810 tube addresses the high-temperature strength degradation that limits conventional heat exchanger materials. At temperatures above approximately 1000°F (538°C), carbon steel begins to graphitize, and standard 300-series stainless steels lose creep strength because their grain structure coarsens during service. UNS N08810 is annealed to a controlled grain size of ASTM No. 5 or coarser, which stabilizes the microstructure and provides the creep and rupture resistance required for sustained operation above 1100°F (593°C). The alloy also resists oxidation and carburization in hot process gases, preventing the wall thinning and embrittlement that would cause tube failure in reformer and cracker service.
Material Specification – ASTM B407 UNS N08810
UNS N08810 is a nickel-iron-chromium alloy with a controlled carbon content of 0.05–0.10% and restricted aluminum and titanium additions. This composition, combined with a high-temperature annealing treatment that produces a coarse grain structure, distinguishes N08810 from the lower-carbon N08800 grade and delivers higher creep and stress-rupture strength at elevated temperatures.
Chemical Composition (per ASTM B407)
| Element | Requirement (%) |
|---|---|
| Nickel (Ni) | 30.0 min |
| Chromium (Cr) | 19.0 – 23.0 |
| Iron (Fe) | Balance |
| Carbon (C) | 0.05 – 0.10 |
| Aluminum (Al) | 0.15 min |
| Titanium (Ti) | 0.60 max |
| Manganese (Mn) | 1.5 max |
| Silicon (Si) | 1.0 max |
| Sulfur (S) | 0.015 max |
| Copper (Cu) | 0.75 max |
Mechanical Properties (Annealed Condition)
| Property | Requirement |
|---|---|
| Tensile Strength, min | 65,000 psi (450 MPa) |
| Yield Strength (0.2% offset), min | 25,000 psi (170 MPa) |
| Elongation in 2 in. (50 mm), min | 30% |
Grain Size Requirement
ASTM B407 requires an average grain size of ASTM No. 5 or coarser for annealed UNS N08810. The controlled grain size is critical: it provides the creep resistance required for service above 1100°F (593°C) and distinguishes the 800H grade from the standard 800 grade. Grain size is determined by the planimetric method in accordance with ASTM E112.
Manufacturing Process
Seamless UNS N08810 tube is produced by hot extrusion or piercing, followed by cold drawing or cold rolling to the specified dimensions. After the final cold-working pass, the tube is annealed at a temperature sufficient to develop the required coarse grain structure (typically in the range of 2100–2200°F / 1150–1200°C), then rapidly cooled. The finished tube is straightened, cut to length, and subjected to hydrostatic or non-destructive electric testing. Tubes can be supplied in straight lengths or U-bend form for U-tube bundle configurations.
Size Range and Dimensional Control
Outside diameter and wall thickness are specified in accordance with ASTM B407 Table 3. Cold-worked tube is supplied commercially straight, uniform in quality and temper, smooth, and free of bends, kinks, and other injurious imperfections. Cut-to-length tolerances are +1/8 in. (3.2 mm) for cold-worked tube, +3/16 in. (4.8 mm) for hot-finished tube, and +1/4 in. (6.4 mm) for lengths over 30 ft. Straightness for hot-finished tube is ≤0.01 in/ft (0.8 mm/m) for OD ≤5 in., and ≤0.015 in/ft (1.4 mm/m) for OD >5 in.
Testing and Quality Control
Each tube is subjected to the following examinations and tests in accordance with ASTM B407 / ASME SB407:
Hydrostatic or Nondestructive Electric Test – Applied to each tube; manufacturer's option unless otherwise specified.
Chemical Analysis – One test per lot.
Mechanical Properties – One tension test per lot; specimens may be full tubular size, longitudinal strip, or round specimens in the direction of fabrication.
Grain Size – One test per lot; ASTM No. 5 or coarser.
Dimensional Inspection – Verification of outside diameter, inside diameter, wall thickness, and length per ASTM B407 Table 3.
Documentation
Each shipment is supplied with Mill Test Certificates (EN 10204 Type 3.1) covering chemical composition and mechanical properties, grain size test reports, hydrostatic or NDE test reports, dimensional inspection reports, and material traceability records.
For a rapid quotation on ASTM B407 UNS N08810 Seamless Tube, please provide the following information:
Quantity (number of pieces or weight)
Outside diameter and wall thickness
Length required (straight or U-bend)
Bend radius and leg length (for U-bend tubes)
Grain size requirement (ASTM No. 5 or coarser)
End preparation (plain ends or beveled ends)
Delivery period required
