Material Family

Nickel-Iron-Chromium Austenitic Alloy (Solid-Solution Strengthened)

An economical alloy for high-temperature service, with lower nickel content than Inconel grades.

Common Forms

Seamless Pipe (SMLS) & Welded Pipe are both widely used.
• Seamless for high-pressure/temperature service.
• Welded for large diameters and cost-sensitive applications.

The most common form is seamless tube and pipe for heat exchanger and furnace applications.

Chemical Composition (Typical wt.%)

Ni: 30.0 - 35.0
Cr: 19.0 - 23.0
Fe: ≥ 39.5 (Balance)
Al: 0.15 - 0.60
Ti: 0.15 - 0.60
C:
• 800: ≤ 0.10
• 800H: 0.05 - 0.10
• 800HT: 0.06 - 0.10 (plus Al+Ti: 0.85-1.20)

High Iron (Fe) content makes it more economical. Balanced Ni/Cr provides oxidation resistance. Controlled C, Al, Ti are critical for the strength of H/HT grades.

Mechanical Properties (Annealed, Room Temp)

Tensile Strength (Rm): 520 - 690 MPa
Yield Strength (Rp0.2): 205 - 345 MPa
Elongation (A): 30 - 45%

Good ductility and moderate strength. The key advantage is strength retention at high temperatures.

Physical Properties

Density: 7.94 g/cm³
Melting Range: 1350 - 1400 °C
Recommended Service Temp: Up to ~700°C for general corrosion; H/HT grades are designed for long-term service above 540°C (1000°F).

Distinction: Standard 800 is for general corrosion; 800H/HT are for high-temperature, high-strength applications.

Key Performance Attributes

• Excellent resistance to oxidation, carburization, and sulfidation.

• Good resistance to chloride stress corrosion cracking and aqueous corrosion.

• Good strength and workability.

• 800H/HT: Superior and predictable creep rupture strength at high temperatures.

An excellent all-rounder for petrochemical and power industry heat exchangers and piping.

Key Standards (Pipe)

Seamless Pipe: ASTM B163 / ASME SB-163, ASTM B407 (for 800H/HT, covers grain size requirements)
Welded Pipe: ASTM B514 / ASME SB-514, ASTM B515 / ASME SB-515

For 800H/HT, compliance with ASTM B407 (coarse grain anneal) is essential to guarantee high-temperature creep properties.

Mandatory Heat Treatment (for 800H/HT Pipe)

Material must be annealed at a minimum of 1121°C (2050°F) to achieve an ASTM grain size of 5 or coarser.

This controlled coarse grain structure is mandatory to develop the specified enhanced creep rupture strength.

Common Sizes & Schedules

OD Range: 1/8" NPS to 24" NPS+
Wall Thickness: Sch 5S, 10S, 40S, 80S, 160, or custom thin walls for tubing.
Length: Random, Double Random, Cut to Length.

Widely used in heat exchanger tubing (small OD, thin wall) and process piping (larger OD).

Typical Applications

• Heat Exchangers: Tubing for shell & tube heaters, superheaters, reheaters in power and chemical plants.
• Petrochemical: Radiant & convection tubes in steam methane reformers (SMR) and ethylene cracking furnaces (800H/HT).
• Industrial Furnaces: Soaking pit covers, annealing covers, retorts.
• Nuclear: Steam generator tubing in some reactor designs.

The most common application is as tubing in high-temperature heat exchangers and furnace systems.