ASTM B622 UNS N10665 Pipe (Hastelloy B-2 / Alloy B2)
ASTM B622 UNS N10665 specifies seamless pipes and tubes manufactured from a nickel-molybdenum alloy known as Hastelloy B-2 or Alloy B2. This alloy is engineered to deliver exceptional resistance to hydrochloric acid at all concentrations and temperatures, as well as to other strong reducing chemicals.
UNS N10665 pipes exhibit excellent resistance to pitting, crevice corrosion, and stress corrosion cracking, making them a preferred material for severe chemical processing and acid-handling applications.
Key Features
- Exceptional resistance to hydrochloric acid in all concentrations
- Excellent performance in reducing environments
- High resistance to pitting and stress corrosion cracking
- Improved thermal stability compared to Hastelloy B
- Good weldability with proper fabrication practices
- Reliable long-term service in aggressive chemical conditions
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | N10665 |
| W.Nr | 2.4617 |
| DIN | NiMo28 |
| Trade Names | Hastelloy B-2, Alloy B2 |
ASTM B622 UNS N10665 Chemical Composition
| Element | Content (%) |
|---|---|
| Nickel (Ni) | Balance |
| Molybdenum (Mo) | 26.0 – 30.0 |
| Iron (Fe) | ≤ 2.0 |
| Cobalt (Co) | ≤ 1.0 |
| Chromium (Cr) | ≤ 1.0 |
| Carbon (C) | ≤ 0.02 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 0.10 |
| Phosphorus (P) | ≤ 0.04 |
| Sulfur (S) | ≤ 0.03 |
Hastelloy B-2 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 690 MPa (min) |
| Yield Strength (0.2% Proof) | 310 MPa (min) |
| Elongation | 40% (min) |
| Hardness | ≤ 95 HRB |
Alloy B2 Physical Properties
| Property | Value |
|---|---|
| Density | 9.24 g/cm³ |
| Melting Range | 1330 – 1370°C |
| Thermal Conductivity | 9.8 W/m·K |
| Electrical Resistivity | 1.20 µΩ·m |
| Modulus of Elasticity | 205 GPa |
Type of ASTM B622 UNS N10665 Pipes
- UNS N10665 Seamless Pipe
- UNS N10665 Seamless Tube
- Hot Finished Pipes
- Cold Drawn Pipes
- Bright Annealed Tubes
- Chemical Process Pipes
- Heat Exchanger Tubes
Applications
- Hydrochloric acid production and handling
- Chemical processing equipment
- Pickling and acid regeneration systems
- Petrochemical and refinery units
- Heat exchangers and condensers
- Pulp and paper industry
- Pollution control and waste treatment systems
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