ASME SB407 Nickel Alloy Pipe | Incoloy 800/800H/800HT Tube
ASME SB407 (corresponding to ASTM B407) is a core standard of the American Society of Mechanical Engineers for nickel alloy pipe and fittings, mainly covering the Incoloy 800 series alloys (UNS N08800, N08810, N08811, etc.). Renowned for their excellent high-temperature strength, creep resistance, oxidation resistance and corrosion resistance, these alloys are the preferred piping materials for severe high-temperature and high-pressure applications in petrochemical, nuclear power, electric power, aerospace and other industries.
1. Standard Definition & Covered Grades
ASME SB407 is officially entitled Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube. It covers the following UNS grades:
- UNS N08800 (Incoloy 800 / 1.4876): General-purpose grade, suitable for service up to 593 °C
- UNS N08810 (Incoloy 800H / 1.4958): Controlled high-carbon grade, optimized for high-temperature creep strength
- UNS N08811 (Incoloy 800HT / 1.4959): Ultra-clean controlled grain grade, ultimate high-temperature endurance performance
- Others: N08120, N08801, N08890, N06811 and other special derivatives
2. Chemical Composition
The SB407 pipe series is an iron-based solid-solution strengthened nickel alloy, achieving balanced performance through precise Ni-Cr-Fe ratio and microalloying.
| Element | N08800 (Incoloy 800) | N08810 (800H) | N08811 (800HT) | Function |
|---|---|---|---|---|
| Ni | 30.0–35.0% | 30.0–35.0% | 30.0–35.0% | Matrix, stress corrosion resistance, heat resistance |
| Cr | 19.0–23.0% | 19.0–23.0% | 19.0–23.0% | Oxidation and corrosion resistance, passive film |
| Fe | Balance | Balance | Balance | Matrix, cost efficiency |
| C | ≤0.10% | 0.05–0.10% | 0.06–0.10% | Grain boundary strengthening for 800H/HT |
| Al+Ti | 0.15–0.60% | 0.15–0.60% | 0.85–1.20% | Precipitation hardening, oxidation resistance |
| Mn | ≤1.5% | ≤1.5% | ≤1.5% | Deoxidation, stability |
| Si | ≤1.0% | ≤1.0% | ≤1.0% | Deoxidation, high-temperature oxidation resistance |
Design Logic: The classic combination of 30% Ni + 20% Cr ensures resistance to chloride-induced stress corrosion cracking (SCC) and stable performance at 800–900 °C. 800H/HT features controlled carbon and Al/Ti content to form coarse grain structure, greatly improving creep and rupture strength.
3. Physical & Mechanical Properties
📐 Physical Properties
Density: 7.94–8.1 g/cm³
Melting Point: 1350–1385 °C
Thermal Conductivity: ~13 W/(m·K) at 20°C
CTE: ~14.4×10⁻⁶/°C (20–800°C)
⚙️ Mechanical Highlights
N08800 (Hot Finished): TS≥450 MPa, YS≥170 MPa, El≥30%
N08800 (Cold Drawn): TS≥520 MPa
800H/800HT: TS≥450 MPa, YS≥170 MPa, El≥30%
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| N08800 (Hot Finished) | ≥450 | ≥170 | ≥30 |
| N08800 (Cold Drawn) | ≥520 | ≥205 | ≥30 |
| N08810 (800H) | ≥450 | ≥170 | ≥30 |
| N08811 (800HT) | ≥450 | ≥170 | ≥30 |
Key High-Temperature Characteristics: Service Temp: 800 up to 593°C; 800H/HT for long-term 800–900°C. Creep/rupture strength far exceeds 304/316 at 650–850°C, excellent oxidation resistance up to 1000°C, superior SCC resistance over austenitic stainless steels.
4. Manufacturing Process & Size Range
🏭 Production Flow
Raw Material (VIM/AIM) → Hot Working (Extrusion/Piercing) → Cold Rolling/Drawing → Solution Annealing (1050–1150°C) → NDT (UT/ET) & Hydrostatic test → Cutting/Beveling
📏 Standard Dimensions
OD: 3mm – 600mm (1/8"–24")
WT: 0.5–30mm (SCH5–SCH XXH)
Length: Fixed 1–12m / random / double random
Condition: Annealed & Pickled (A/P), Bright Annealed (BA)
Inspection: Chemical analysis, mechanical properties, grain size, corrosion tests per SB407.
5. Typical Industrial Applications
🛢️ Petrochemical Industry
Furnace tubes, reformer tubes, hydrogenation reactor bundles, high-temperature process piping, Heat Recovery Steam Generators, heat exchangers, steam generators.
⚛️ Nuclear & Thermal Power
Reactor cooling systems, steam generator tubes, pressurizer piping, boiler superheaters, reheater tubes, high-temperature headers for waste-to-energy & biomass.
✈️ Aerospace & Special Equipment
Engine exhaust pipes, heat exchangers, high-temperature hydraulic lines, industrial furnaces, heat treatment equipment, chemical cracking tubes.
🌊 Other Severe Conditions
Offshore platforms, desulfurization & denitrification systems, sour gas treatment, high-temp corrosion equipment in food processing, paper and fertilizer industries.
6. Selection & Application Notes
📌 Grade Differentiation
Up to 593°C, low creep → N08800
593–800°C, creep strength → N08810 (800H)
Above 800°C, ultra-high endurance → N08811 (800HT)
✅ Advantages Over Alternatives
Superior to 304/316: higher temperature resistance, SCC resistance, creep strength. Superior to pure nickel/Inconel: lower cost, better workability, good toughness.
🔧 Fabrication & Welding
GTAW/GMAW recommended, matching filler ERNiCr-3. Moderate work hardening, intermediate annealing required. Strict solution annealing 1050–1150°C to ensure grain size and properties.
🏭 Economizer & Boiler Integration
ASME SB407 alloys are widely used in high-efficiency units such as Cast Iron Economizer, H-Fin Tube Economizer, and Studded Pipe Economizer systems, delivering outstanding corrosion resistance in harsh environments.
7. Conclusion
ASME SB407 nickel-iron-chromium alloy pipe is a benchmark material for combined high-temperature and corrosive environments. Centered on Incoloy 800/800H/HT, it achieves an excellent balance of heat resistance, corrosion resistance, mechanical properties and cost efficiency. From petrochemical furnaces to nuclear steam generators, from aero-engines to industrial cracking furnaces, SB407 piping provides stable and reliable performance, making it an indispensable component for modern high-end equipment and process industries.
With the trend of energy transformation and equipment upgrading, its value in high-efficiency, long-life and safe systems will continue to grow. Whether for reformer tubes, Heat Recovery Steam Generators, or advanced economizer designs, ASME SB407 remains the trusted choice for engineers worldwide.