Material Family

Nickel-Chromium-Molybdenum-Tungsten Superalloy (Wrought, Low-Carbon)

Represents an optimized, "third-generation" C-type alloy with enhanced versatility.

Common Forms

Seamless Pipe (SMLS) & Welded Pipe
• Seamless: Preferred for the most severe, critical corrosion service and high-purity applications.
• Welded: Cost-effective for large diameters and less severe process lines.

Seamless pipe provides the highest reliability for handling aggressive, mixed chemical streams.

Chemical Composition (Typical wt.%)

Ni: ≥ 56.0 (Balance)
Cr: 20.0 - 22.5
Mo: 12.5 - 14.5
W: 2.5 - 3.5
Fe: 2.0 - 6.0
C: ≤ 0.010
Si: ≤ 0.08

Higher Chromium (Cr) than C-276 improves resistance to oxidizing media. Balanced Mo & W provide stability in reducing conditions. Very Low C & Si prevent sensitization.

Mechanical Properties (Annealed, Room Temp)

Tensile Strength (Rm): 690 - 827 MPa
Yield Strength (Rp0.2): 310 - 414 MPa
Elongation (A): 45 - 55%

High strength combined with excellent ductility and toughness for forming and bending.

Physical Properties

Density: 8.69 g/cm³
Melting Range: 1355 - 1395 °C

Slightly lower density than C-276 due to optimized chemistry.

Key Corrosion Resistance

• Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking – superior to C-276.
• Excellent resistance to both oxidizing and reducing media, including mixed acids (e.g., HNO₃ + HF).
• Superior resistance to hot contaminated mineral acids, salts, and seawater.
• Excellent performance in oxidizing chloride solutions (e.g., FeCl₃, CuCl₂).

Considered to have the broadest corrosion resistance of any commercially available wrought alloy pipe, ideal for unpredictable or fluctuating process streams.

Key Standards (Pipe)

Seamless Pipe: ASTM B622 / ASME SB-622 (Grade UNS N06022)
Welded Pipe: ASTM B619 / ASME SB-619, ASTM B626 / ASME SB-626 (Welded, UNS N06022)

Procured under the same ASTM standards as C-276 pipe, but to the N06022 composition.

Common Sizes & Schedules

OD Range: 1/8" NPS to 24" NPS+
Wall Thickness: Sch 5S, 10S, 40S, 80S, 160 (per ASME B36.19M)
Length: Random, Double Random, Cut to Length.

Available in full piping schedules. Often used in thin walls for heat exchanger tubes and cladding.

Fittings & Fabrication

Compatible with ASTM B366 wrought fittings. Excellent weldability using matching filler metal (ERNiCrMo-10). Like C-276, it exhibits excellent as-welded corrosion resistance without requiring post-weld heat treatment.

The optimized chemistry further enhances the stability of the weld zone.

Typical Applications

• Chemical Processing: Reactor piping for mixed acids, chlorine dioxide systems, harsh alkylation processes.
• Pollution Control (FGD): Absorber tower spray headers, mist eliminator wash piping, ducting in severe scrubber environments.
• Pharmaceutical: High-purity process piping for aggressive multi-step synthesis.
• Waste Treatment: Piping for advanced oxidation processes and severe waste incineration.
• Marine: Seawater piping in highly polluted or high-temperature conditions.

The material of choice for critical piping systems where reliability in the face of complex, aggressive chemistry is paramount.