## Common ground
All options refer to ship chains, which are heavy-duty metal links used for anchoring ships.
## Options at a glance
**7315.12 – Iron or steel**
- **Defining trait:** Made from iron or steel, offering high tensile strength and durability.
- **Typical examples:** Anchor chains for large cargo vessels, offshore platforms.
- **Best fit when:** Maximum strength and resistance to wear are required in harsh marine environments.
**7419 – Copper**
- **Defining trait:** Made from copper or copper alloys, known for corrosion resistance and non-magnetic properties.
- **Typical examples:** Specialized chains for sensitive equipment or underwater applications where magnetic interference must be avoided.
- **Best fit when:** Corrosion resistance and non-magnetic use are critical, despite lower strength.
**7616.9X – Aluminium**
- **Defining trait:** Made from aluminium, offering lightweight construction with moderate strength.
- **Typical examples:** Light-duty chains for small boats or temporary mooring systems.
- **Best fit when:** Weight reduction is essential and loads are relatively light.
## Key differences
| Feature | 7315.12 (Iron/Steel) | 7419 (Copper) | 7616.9X (Aluminium) |
|------------------|----------------------|---------------------|---------------------|
| Strength | Very high | Moderate | Low to moderate |
| Weight | Heavy | Medium | Light |
| Corrosion resistance | Low (requires coating) | Very high | High |
| Magnetic properties | Magnetic | Non-magnetic | Non-magnetic |
## How to choose
- Is the chain used for large ships or heavy anchoring? → 7315.12
- Does it need to resist corrosion in saltwater or avoid magnetic interference? → 7419
- Is weight a major concern, and is the load light? → 7616.9X
## Overlaps & pitfalls
A chain could be made of copper alloy with high strength (e.g., naval brass), potentially overlapping 7419 and 7315.12. However, copper alloys are not classified under iron/steel. The key is the primary material: if it's steel, use 7315.12; if copper or aluminium, use their respective codes. No priority rule is implied—choose based on the dominant material