ASTM B622 UNS N06686 Pipe (Inconel 686 / Alloy 686)
ASTM B622 UNS N06686 specifies seamless pipes and tubes manufactured from a nickel-chromium-molybdenum-tungsten alloy known as Inconel 686 or Alloy 686. This alloy is specifically developed to provide outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking in extremely aggressive environments.
UNS N06686 pipes offer superior performance in chloride-rich, acidic, and mixed chemical conditions, outperforming many other nickel alloys, making them ideal for the most demanding chemical processing and marine applications.
Key Features
- Exceptional resistance to pitting and crevice corrosion
- Outstanding performance in chloride-bearing environments
- Superior resistance to stress corrosion cracking
- Excellent corrosion resistance in both oxidizing and reducing media
- Good weldability and fabrication characteristics
- Long service life in highly aggressive chemical conditions
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | N06686 |
| W.Nr | 2.4606 |
| DIN | NiCr21Mo16W |
| Trade Names | Inconel 686, Alloy 686 |
ASTM B622 UNS N06686 Chemical Composition
| Element | Content (%) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 19.0 – 23.0 |
| Molybdenum (Mo) | 15.0 – 17.0 |
| Tungsten (W) | 3.0 – 4.4 |
| Iron (Fe) | ≤ 1.0 |
| Cobalt (Co) | ≤ 2.5 |
| Carbon (C) | ≤ 0.01 |
| Manganese (Mn) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.08 |
| Phosphorus (P) | ≤ 0.02 |
| Sulfur (S) | ≤ 0.01 |
Inconel 686 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 690 MPa (min) |
| Yield Strength (0.2% Proof) | 310 MPa (min) |
| Elongation | 40% (min) |
| Hardness | ≤ 95 HRB |
Alloy 686 Physical Properties
| Property | Value |
|---|---|
| Density | 8.69 g/cm³ |
| Melting Range | 1320 – 1370°C |
| Thermal Conductivity | 9.0 W/m·K |
| Electrical Resistivity | 1.25 µΩ·m |
| Modulus of Elasticity | 205 GPa |
Type of ASTM B622 UNS N06686 Pipe
- UNS N06686 Seamless Pipe
- UNS N06686 Seamless Tube
- Hot Finished Pipes
- Cold Drawn Pipes
- Bright Annealed Tubes
- Chemical Process Pipes
- Heat Exchanger Tubes
Applications
- Chemical processing equipment
- Offshore and marine piping systems
- Heat exchangers and condensers
- Pollution control and scrubber systems
- Acid handling and transfer lines
- Petrochemical and refinery units
- Pharmaceutical processing plants
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