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-iron-chromium (Ni-Fe-Cr) seamless pipes 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. Our nickel alloy pipe strictly complies with this international specification.
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, all available as standard SB407 pipe products:
- 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
Core Positioning: Designed specifically for working conditions combining high temperature (above 593 °C), high pressure and corrosive media, distinct from ordinary stainless steel and low-nickel alloys.
2. Chemical Composition
The SB407 series is a 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
3.1 Physical Properties
- Density: Approx. 7.94–8.1 g/cm³
- Melting Point: 1350–1385 °C
- Thermal Conductivity: Approx. 13 W/(m·K) at 20 °C, stable at high temperatures
- Coefficient of Thermal Expansion: Approx. 14.4×10⁻⁶/°C (20–800 °C), compatible with most structural materials
3.3 Key High-Temperature Characteristics
- Service Temperature: 800 up to 593 °C; 800H/HT for long-term service at 800–900 °C
- Creep/Rupture Strength: 800H/HT far exceeds 304/316 stainless steel at 650–850 °C
- Oxidation Resistance: Excellent oxidation, carburization and nitriding resistance at up to 1000 °C in air
- Corrosion Resistance: Resistant to nitric acid, organic acids, alkalis and steam; superior SCC resistance over austenitic stainless steels
3.2 Room-Temperature Mechanical Properties (Solution Annealed, Minimum Values)
| 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 |
4. Manufacturing Process & Size Range
4.1 Production Flow (Seamless Pipe)
- Raw Material: Vacuum induction / arc melting for high purity
- Hot Working: Extrusion / piercing → hot rolling → sizing
- Cold Working: Cold rolling / cold drawing for precision and surface finish
- Heat Treatment: Solution annealing (1050–1150 °C) with rapid cooling
- Finishing: Pickling / bright annealing → NDT (UT/ET) → hydrostatic test → cutting / beveling
- Inspection: Chemical analysis, mechanical properties, grain size, corrosion tests per SB407
4.2 Standard Dimensions
- Outside Diameter (OD): 3 mm – 600 mm (1/8" – 24")
- Wall Thickness (WT): 0.5 mm – 30 mm (SCH 5 to SCH XXH)
- Length: Fixed length (1–12 m), random length, double random length
- Condition: Solution Annealed & Pickled (A/P), Bright Annealed (BA)
- Ends: Plain end, beveled end, threaded
5. Typical Industrial Applications
ASME SB407 alloy pipe is widely used in core high-end process industries due to its combined high-temperature and corrosion resistance:
5.1 Petrochemical Industry
- Furnace tubes, reformer tubes, hydrogenation reactor bundles
- High-temperature process piping, heat exchangers, steam generators
- Fluid piping resistant to sulfur, chlorine and hydrogen corrosion
5.2 Nuclear Power
- Reactor cooling systems, steam generator tubes, pressurizer piping
- Nuclear-grade requirements: high purity, low inclusions, long service life, radiation resistance
5.3 Thermal Power
- Boiler superheaters, reheater tubes, high-temperature headers
- High-temperature corrosion piping for waste-to-energy and biomass power plants
5.4 Aerospace & Special Equipment
- Engine exhaust pipes, heat exchangers, high-temperature hydraulic lines
- Industrial furnaces, heat treatment equipment, chemical cracking tubes
5.5 Other Severe Conditions
- High-temperature corrosion equipment in food processing, papermaking and fertilizer industries
- Offshore platforms, desulfurization and denitrification systems, sour gas treatment
6. Selection & Application Notes
Grade Differentiation
- Up to 593 °C, low creep requirement: N08800
- 593–800 °C, long-term creep strength required: 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
- Welding: GTAW/GMAW recommended, matching filler ERNiCr-3
- Cold working: Moderate work hardening, intermediate annealing required
- Heat treatment: Strict 1050–1150 °C solution annealing to ensure grain size and properties
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.