ASTM A407 N08810 Heat Exchanger Tube Chemical Composition
| UNS Designation |
Ni |
Cu |
Iron |
Mn |
C |
Cr |
Ti |
Al |
| N08810 |
0.30–0.35 |
0.75 |
39.5 |
1.5 |
0.05–0.10 |
19.0-23.0 |
0.15-0.60 |
0.15-0.60 |
ASTM B407 N08810 Heat Exchanger Tube Application
Tubes are used in extreme environments:
- Petrochemical: Ethylene furnace coils, reformer tubes, pyrolysis units.
- Power Generation: Superheater tubes, heat exchangers, boiler components.
- Nuclear: Steam generator tubing, heat exchangers (resists chloride stress corrosion).
- Industrial Furnaces: Radiant tubes, muffles, conveyor systems.
- Chemical Processing: Acid production, catalyst support grids.
| Application |
Primary Challenge |
800H’s Advantage |
| Ethylene cracking |
Carburization + creep |
Controlled carbon + Ni/Cr matrix stability |
| Nuclear steam gens |
SCC in chlorides |
>30% Ni content prevents cracking |
| Reformer tubes |
Hydrogen embrittlement |
Stable austenitic structure |
| Radiant furnace tubes |
Cyclic oxidation/carburizing |
Al/Ti oxide layer formation |
ASTM B407 N08810 Heat Exchanger Tube Strength & Mechanical Properties
Tensile Strength: ≥500 MPa (72.5 ksi)
Yield Strength (0.2% offset): ≥170 MPa (25 ksi)
Elongation: ≥30%
- Elevated Temperature (650°C / 1200°F):
Tensile Strength: ~380 MPa (55 ksi)
Creep Rupture Strength: Excellent (e.g., 10,000 hrs at 815°C: ~20 MPa)
- Key Strengths: Retains structural integrity under thermal cycling/stress; superior to standard stainless steels (e.g., 304/316) above 600°C.
- High-Temperature Performance: Outperforms stainless steels in creep strength above 600°C.
- Corrosion Resistance: Resists oxidation, carburization, and reducing sulfur atmospheres.
- Fabricability: Weldable (using ENiCrFe-3 filler) and formable with standard methods.
- Cost-Effective: More economical than high-nickel alloys (e.g., Inconel) for moderate temperatures.
ASTM B407 N08810 Heat Exchanger Tube FAQ
1. What distinguishes Incoloy 800H from standard Incoloy 800?
800H has a higher carbon content (0.05–0.10% vs. 0.03% max in 800) for superior creep resistance at >600°C.
It undergoes solution annealing at ≥1100°C to achieve an ASTM No. 5 or coarser grain size, optimizing high-temperature strength.
2. What temperatures can Incoloy 800H tubes handle?
Continuous Service: Up to 815°C (1500°F).
Short-Term Exposure: Up to 950°C (1740°F).
Critical Note: For >900°C, Incoloy 800HT (Ti/Al-controlled) is preferred for enhanced stability.
3. Is welding 800H tubes difficult?
Weldable via:
TIG/GTAW with ERNiCr-3 (FM 82) filler.
SMAW with ENiCrFe-3 electrodes.
Post-Weld Requirement: Solution annealing (1100–1175°C) is essential to restore corrosion/creep resistance.
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