ASTM B423 UNS N08221 (Alloy 825) Nickel Alloy Seamless Pipe
ASTM B423 UNS N08221 (Alloy 825) seamless pipe is a nickel-iron-chromium alloy enriched with molybdenum, copper, and titanium for superior corrosion resistance in aggressive and high-temperature environments. Known for its remarkable resistance against sulfuric acid, phosphoric acid, seawater, and stress-corrosion cracking, Alloy 825 is widely used in chemical processing, petrochemical, marine, and oil & gas sectors. Its excellent mechanical strength, stability, and long service life make it a preferred choice for demanding industrial applications.
Key Features
- Excellent corrosion resistance in both oxidizing and reducing environments
- High resistance to sulfuric acid, phosphoric acid, and seawater corrosion
- Stable mechanical performance at elevated temperatures
- Titanium-stabilized for improved resistance to intergranular corrosion
- Suitable for chemical, petrochemical, and offshore applications
- High strength and durability with superior metallurgical stability
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | N08221 |
| EN | NiCr21MoCu |
| WNR | 2.4858 (Reference Alloy 825 Family) |
| Trade Name | Alloy 825 |
Available Sizes
Pipe Size Range
- From 1/8″ IPS up to 48″ OD
- Available in full NPS range including 1/2″, 1″, 2″, 4″, 6″, 10″, 12″, 16″, 18″, and more
Tube Size Range
- Outside Diameter (OD): 3 mm to 600 mm
Wall Thickness
- As per size and schedule: SCH 5, 10, 40, 80, 120, 160, XXS
- Thickness typically ranges from 0.5 mm up to 30 mm or more depending on product and application
Length Availability
- Supplied in Single Random Length (SRL), Double Random Length (DRL), or Custom Cut Lengths
- Standard length tolerance: approx. ± 3.5 ft for random lengths
ASTM B423 UNS N08221 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Nickel (Ni) | 38.0 – 46.0 |
| Chromium (Cr) | 19.5 – 23.5 |
| Iron (Fe) | Balance |
| Molybdenum (Mo) | 2.5 – 3.5 |
| Copper (Cu) | 1.5 – 3.0 |
| Titanium (Ti) | 0.6 – 1.2 |
| Carbon (C) | ≤ 0.05 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 0.5 |
| Sulfur (S) | ≤ 0.03 |
UNS N08221 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 550 MPa |
| Yield Strength (0.2% Offset) | ≥ 220 MPa |
| Elongation | ≥ 30% |
| Hardness | ≤ 200 HB |
Alloy 825 Physical Properties
| Property | Value |
|---|---|
| Density | 8.14 g/cm³ |
| Melting Range | 1370 – 1400°C |
| Thermal Conductivity | 11 W/m·K at 20°C |
| Electrical Resistivity | 1.15 μΩ·m |
| Modulus of Elasticity | 195 GPa |
Type of ASTM B423 UNS N08221 Pipes
- ASTM B423 UNS N08221 Seamless Pipes
- ASTM B423 UNS N08221 Seamless Tubes
- Cold Drawn Alloy 825 Tubes
- Hot Finished Alloy 825 Pipes
Applications
- Chemical processing equipment
- Heat exchangers and condensers
- Oil & gas offshore piping systems
- Marine and seawater service lines
- Pollution control systems
- Acid production and handling equipment
- Petroleum refining equipment
- Nuclear reprocessing plants
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