Understanding Stainless Steel Wire Breaking Strains
Stainless steel wire rope is a critical component in marine, architectural, and industrial applications due to its strength, durability, and corrosion resistance. One of the most important specifications when selecting wire rope is its breaking strain—the maximum load the wire can withstand before failure.
What Is Breaking Strain?
Breaking strain (also known as Minimum Breaking Load, or MBL) is the force required to cause a wire rope to fail. It’s measured in kilograms (kg) or kilonewtons (kN), and varies depending on:
- Wire construction (e.g., 1x19, 7x19, compact strand)
- Material grade (typically AISI 316 stainless steel)
- Diameter of the wire
To ensure safety, wire ropes should never be loaded to their full breaking strain. A safety factor—commonly 5:1—is applied to determine the Safe Working Load (SWL).
Stainless Steel Wire Breaking Load Comparison
Here’s a table comparing breaking loads for different wire constructions and diameters. All values are approximate and based on manufacturer ratings for AISI 316 stainless steel.
| Wire Diameter | KOS 7x19 | KOS 1x19 | Compacted Strand |
|---|---|---|---|
| 2 mm | 225 kg | 320 kg | 440 kg |
| 2.5 mm | 355 kg | 500 kg | 690 kg |
| 3 mm | 510 kg | 720 kg | 1000 kg |
| 4 mm | 910 kg | 1280 kg | 1780 kg |
| 5 mm | 1420 kg | 2000 kg | 2600 kg |
| 6 mm | 2040 kg | 2880 kg | 3600 kg |
| 7 mm | 2780 kg | 3560 kg | 5000 kg |
| 8 mm | 3630 kg | 4640 kg | 6300 kg |
| 10 mm | 5670 kg | 7250 kg | 10000 kg |
| 12 mm | 7660 kg | 10400 kg | 14500 kg |
Note: These values are for reference only. Always consult manufacturer specifications and apply appropriate safety factors for your application.
Choosing the Right Wire Rope
When selecting stainless steel wire rope, consider:
- Application: Static rigging vs. dynamic loads
- Flexibility: 7x19 is more flexible than 1x19
- Aesthetic: Compact strands offer a sleeker look
- Environment: Marine-grade AISI 316 is ideal for corrosion resistance
Final Thoughts
Understanding breaking strains is essential for safe and effective use of stainless steel wire rope. Whether you're rigging a yacht, installing a balustrade, or designing a suspension system, choosing the right wire with the correct load rating ensures performance and safety.
If you’d like help calculating safe working loads or selecting fittings, we would be happy to assist!