ASTM B622 UNS N06985 Pipe (Hastelloy G-3 / Alloy G-3)
ASTM B622 UNS N06985 specifies seamless pipes and tubes manufactured from a nickel-chromium-iron-molybdenum-copper alloy known as Hastelloy G-3 or Alloy G-3. This grade is an improved version of the original G-series alloys, offering enhanced corrosion resistance, better weldability, and improved thermal stability.
UNS N06985 pipes are widely used in chemical processing environments, particularly where resistance to phosphoric acid, sulfuric acid, and chloride-containing solutions is required.
Key Features
- Excellent resistance to phosphoric and sulfuric acids
- Improved weldability and fabricability over earlier G-series alloys
- Good resistance to pitting and crevice corrosion
- Stable mechanical properties at elevated temperatures
- Reliable performance in chloride-containing environments
- Long service life in chemical processing applications
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | N06985 |
| W.Nr | 2.4619 |
| DIN | NiCr22Fe18Mo |
| Trade Names | Hastelloy G-3, Alloy G-3 |
ASTM B622 UNS N06985 Chemical Composition
| Element | Content (%) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 21.0 – 23.0 |
| Iron (Fe) | 18.0 – 21.0 |
| Molybdenum (Mo) | 6.0 – 8.0 |
| Copper (Cu) | 1.5 – 2.5 |
| Cobalt (Co) | ≤ 5.0 |
| Carbon (C) | ≤ 0.03 |
| Manganese (Mn) | ≤ 1.50 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.04 |
| Sulfur (S) | ≤ 0.02 |
Hastelloy G-3 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 620 MPa (min) |
| Yield Strength (0.2% Proof) | 240 MPa (min) |
| Elongation | 40% (min) |
| Hardness | ≤ 95 HRB |
Alloy G-3 Physical Properties
| Property | Value |
|---|---|
| Density | 8.28 g/cm³ |
| Melting Range | 1320 – 1370°C |
| Thermal Conductivity | 11.2 W/m·K |
| Electrical Resistivity | 1.20 µΩ·m |
| Modulus of Elasticity | 205 GPa |
Type of ASTM B622 UNS N06985 Pipes
- UNS N06985 Seamless Pipe
- UNS N06985 Seamless Tube
- Hot Finished Pipes
- Cold Drawn Pipes
- Bright Annealed Tubes
- Chemical Process Pipes
- Heat Exchanger Tubes
Applications
- Phosphoric acid production plants
- Sulfuric acid handling systems
- Chemical processing equipment
- Fertilizer and agrochemical industries
- Heat exchangers and condensers
- Pickling and metal finishing lines
- Petrochemical and refinery services



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