Incoloy 800HT Seamless Tube

UNS N08811 | 1.4959 | ASTM B407

Incoloy 800HT Seamless Tube (N08811 / 1.4959) is manufactured to ASTM B407 from tube billet, cold-drawn to the required outside diameter and wall thickness. Supplied from our Wenzhou mill with EN 10204 3.1 mill test certificate, PMI and dimensional inspection on request.

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Incoloy 800HT Product Overview and Advantages

What is Seamless Incoloy 800HT Tubing?

SeamlessIncoloy 800HT tubing (UNS N08811) is a high-performance nickel-iron-chromium alloy tube specifically engineered for long-term service in high-temperature and high-stress environments.

Unlike welded tubing, seamless Incoloy 800HT tubes are produced through hot piercing and precision cold drawing from a solid billet, resulting in a continuous metallurgical structure without weld seams. This seamless construction improves pressure integrity, creep resistance, and structural reliability in critical industrial systems.

The 800HT designation represents an advanced version of the Incoloy 800 alloy family. It features:

Controlled carbon content: 0.05 – 0.10%
Optimized Aluminum + Titanium (Al + Ti): 0.85 – 1.20%
High-temperature solution annealing treatment

This metallurgical design significantly enhances creep strength and stress-rupture resistance at temperatures above 1100°F (593°C), making Incoloy 800HT seamless tubing ideal for petrochemical furnaces, steam reformers, and high-temperature heat exchangers.

Key Technical Advantages of Seamless Incoloy 800HT Tubes

Seamless Incoloy 800HT tubes provide outstanding performance in extreme thermal and chemical environments:

Enhanced Creep and Stress-Rupture Strength

Optimized carbon and Al+Ti content significantly increases creep resistance compared with Incoloy 800 (N08800) and Incoloy 800H (N08810), allowing reliable operation in long-term high-temperature service.

Exceptional High-Temperature Stability

The alloy maintains a stable austenitic microstructure and excellent mechanical strength during prolonged exposure to temperatures up to 2012°F (1100°C).

Superior Oxidation and Carburization Resistance

The high nickel and chromium content provides strong resistance to:

Oxidation
Carburization
Nitriding

This makes the alloy particularly suitable for petrochemical furnaces and heat-treatment equipment.

Seamless Structural Integrity

The seamless production process eliminates longitudinal weld seams, removing potential weak points such as heat-affected zones (HAZ) and ensuring uniform thermal expansion under cyclic heating conditions.

Excellent Fabrication and Weldability

Despite its high-temperature strength, Incoloy 800HT tubing remains readily formable and weldable, using compatible filler metals for reliable fabrication.

Incoloy 800HT Product Specifications and Data

To provide a comprehensive overview of this high-performance material, here are the detailed technical specifications and performance data for Incoloy 800HT.

Table 1: Chemical Composition of Incoloy 800HT Under ASTM B407

The enhanced strength of Incoloy 800HT is a direct result of its controlled carbon, aluminum, and titanium content, while retaining the essential nickel and chromium levels for heat and corrosion resistance.

Grade	Ni	Cu	Fe	Mn	C	Si	S	Cr	Al	Ti	P	Others
800	30.00-35.00	≤0.75	≥39.50	≤1.50	≤0.10	≤1.00	≤0.015	19.00-23.00	0.15-0.60	0.15-0.60	≤0.045	-
800H	30.00-35.00	≤0.75	≥39.5	≤1.50	0.05-0.10	≤1.00	≤0.015	19.00-23.00	0.15-0.60	0.15-0.60	-	-
800HT	30.00-35.00	≤0.75	≥39.5	≤1.50	0.06-0.10	≤1.00	≤0.015	19.00-23.00	0.25-0.60	0.25-0.60	≤0.045	AL+Ti= 0.85-1.20

Incoloy 800HT is specifically designed to maintain its strength and shape in high-stress, high-temperature applications.

Typical Mechanical Properties of Incoloy 800HT Under ASTM B407

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 450 MPa	≥ 170 MPa	≥ 30%	≤ 192 HB

These physical properties highlight the material's ability to perform reliably under extreme thermal conditions.

Typical Physical Properties of Incoloy 800HT Under ASTM B407

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.03 g/cm³	1357 - 1400 °C approx.	15.0 µm/m·°C (20-100°C)	11.2 W/m·K (20°C)	196 GPa	1.06 x 10⁻⁶ Ω·m (20°C)

Table 4: The Standard of Seamless Incoloy 800HT Pipe ASTM B407 Size Tolerance Chart :

Cold-Finished Pipes and Tubes:

Specified/Calculated Nominal OD (Inches)	Permissible Variation (Inches)	Specified/Calculated Nominal OD (mm)	Permissible Variation (mm)
0.500 to 5⁄8, excl.	±0.005	12.7 to 15.8, excl.	±0.127
5⁄8 to 1 1⁄2, incl.	±0.0075	15.8 to 38.1, incl.	±0.190
Over 1 1⁄2 to 3 1⁄2, incl.	±0.010	Over 38.1 to 88.9, incl.	±0.254
Over 3 1⁄2 to 4 1⁄2, incl.	±0.015	Over 88.9 to 114.3, incl.	±0.381
Over 4 1⁄2 to 6, incl.	±0.020	Over 114.3 to 152.4, incl.	±0.508
Over 6 to 6 5⁄8, incl.	±0.025	Over 152.4 to 168.3, incl.	±0.635

Specified/Calculated Nominal OD (Inches)	Permissible Variation (Inches)	Specified/Calculated Nominal OD (mm)	Permissible Variation (mm)
2 1⁄2 to 5 1⁄2, excl.	±0.031	63.5 to 139.7, excl.	±0.787
5 1⁄2 to 9 1⁄4, incl.	±0.047	139.7 to 234.9, incl.	±1.19

Condition	Specified/Calculated Nominal OD (Inches)	Permissible Variation (Wall Thickness)
Cold-Finished	0.500 to 5⁄8, excl.	±15.0%
	5⁄8 to 4 1⁄2, incl.	±10.0%
	Over 4 1⁄2 to 6 5⁄8, incl.	±12.5%
Hot-Finished	2 1⁄2 to 9 1⁄4, incl.	±12.5%

Major Industrial Applications of Seamless Incoloy 800HT Tube

Industry	Typical Applications
	Due to its high creep strength and excellent high-temperature corrosion resistance, seamless Incoloy 800HT tubes are widely used in demanding industrial sectors:

Industry	Typical Applications
Petrochemical & Chemical Processing	Ethylene furnace quench systems Steam methane reformer (SMR) pigtails High-temperature heat exchangers
Power Generation	Superheater and reheater tubes High-temperature steam pipelines Nuclear and coal-fired power plant systems

Industry	Typical Applications
Industrial Heat Treatment	Furnace radiant tubes Retorts and muffles Conveyor systems for heat-treating equipment
Renewable Energy Systems	Concentrated solar power (CSP) receivers Thermal energy storage systems

Incoloy 800HT Incoloy 800 Series Comparison

Property	Incoloy 800 (N08800)	Incoloy 800H (N08810)	Incoloy 800HT (N08811)
Carbon Content	≤0.10%	0.05 - 0.10%	0.05 - 0.10%
Al +Ti Content	0.30% - 1.20%	0.30% - 1.20%	0.85% - 1.20%
Annealing Temp	Mill Anneal	High-Temp Anneal	High-Temp Anneal
Best Used For	General Corrosion	Creep Resistance	Maximum Creep Strength

Incoloy 800HT Comparison with Other High-Performance Alloys

*Note:Nickel 201 is recommended for temperatures above 600°F to prevent graphitization.

Alloy Grade	Common Standards	Key Advantage	Max Service Temp	Best For...
Inconel 601	UNS N06601	Exceptional Oxidation	2200°F (1204°C)	Furnace components, Radiant tubes
Incoloy 800HT	UNS N08811	Maximum Creep Strength	2012°F (1100°C)	Ethylene furnaces, Steam reformers
Nickel 200	UNS N02200	Caustic Resistance	600°F (315°C)*	Caustic soda (NaOH) handling
Super Duplex S32760	UNS S32760	PREN ≥41 Strength	600°F (315°C)	Offshore Oil & Gas, Desalination
Inconel 625	UNS N06625	Pitting & Fatigue Res.	1800°F (982°C)	Marine exhaust, Chemical reactors

Frequently Asked Questions About Incoloy 800HT Seamless Tubes

What is Incoloy 800HT Seamless Tube?

Seamless Incoloy 800HT tubing (UNS N08811) is a high-performance nickel-iron-chromium alloy tube specifically engineered for long-term service in high-temperature and high-stress environments.

Which standards does Incoloy 800HT Seamless Tube comply with?

Incoloy 800HT Seamless Tube is produced to ASTM B407.

What are the typical applications of Incoloy 800HT Seamless Tube?

Typical uses of Incoloy 800HT Seamless Tube include: Ethylene furnace quench systems; Steam methane reformer (SMR) pigtails; High-temperature heat exchangers; Superheater and reheater tubes.

Request a Incoloy 800HT Tube Quotation

Send us your specification for Seamless Incoloy seamless tube — OD, wall thickness, standard and quantity — and our engineering team will reply with a quotation within 24 hours.