Steel strapping has been used for heavy cargo for decades because it is strong, rigid, and reliable. But export cargo creates a different problem. During a long journey, loads can settle, cartons can compress, timber can shrink, and machinery can shift slightly on its base. When that happens, the strap needs to keep holding the load tightly.
This is where composite cord strapping behaves differently from steel. Steel has very little stretch, so once the load becomes slightly smaller, the band can lose tension. A composite cord strap can stretch a little and recover, which helps it stay tight as the cargo moves and settles during transport. That difference is one of the main reasons many exporters compare composite cord strap with steel strapping.
Overview of Composite Cord and Steel Strapping
Steel strapping is cold-rolled carbon steel, usually 0.4–1.0 mm thick, sealed with a metal seal or a friction weld. It’s been the default for heavy bundling since the 1920s and it earned that position honestly.
Composite cord strapping is bonded polyester filaments — thousands of high-tenacity yarns running in one direction — encased in a polymer coating and embossed for grip. It’s closed with a galvanised wire buckle, no tool welding, no seal.
The two materials do the same job through completely different mechanisms. Steel resists by rigidity. Composite resists tension.
Tension Retention and Load Settling
Here’s the mechanism, and it explains most of what follows.
When you strap a load, the load settles. Timber loses moisture and shrinks. Cartons compress. Machinery beds into its dunnage. Vibration works everything a millimetre tighter. Every load loses volume in the first 48 hours of transit — that’s not a defect, it’s just what happens.
Steel has almost no working elongation. Tension it to its limit and there is nothing in reserve. The load shrinks 3 mm and the band goes slack. And a slack steel band does not re-tension — it just sits there, and now your cargo has a few millimetres of play, and a few millimetres of play at 0.8 g becomes an impact load.
Polyester cord strap has working elongation in the low single digits and, critically, recovery. It stretches under shock and pulls back. The load settles, the strap takes up the slack. Same journey, tension still there on day nine.
That’s it. That’s the whole argument. Everything else below is secondary.
Workplace Safety
Steel banding under tension is a stored-energy device. When it fails — or when someone cuts it wrong at the destination — it whips. Cut edges are sharp enough to open a hand through a glove, and steel strapping injuries are a routine line item in warehouse incident reports.
Cord strap fails differently. It parts and drops. There’s no whip, no blade, no stored energy release. Cutting it needs a snip, not a bolt cutter, and the cut end is soft.
If your buyer runs a formal safety programme, this often decides the question before price does. We’ve had customers switch entirely because their European consignee refused to unpack steel-banded goods.
Corrosion Resistance and Weather Performance
Steel rusts. On a 40-day sea crossing with salt air and condensation cycling inside a steel box, it doesn’t just cosmetically rust — the rust bleeds onto the cargo. Galvanised and painted steel band delays it. Nothing stops it.
Polyester doesn’t corrode, doesn’t stain, and holds its properties across roughly −50 °C to +80 °C, which covers every commercial shipping route. It’s UV-stable enough for outdoor yard storage, though nothing polymer likes a year in direct tropical sun.
Cargo Protection and Surface Damage
Steel band bites. On coated steel, powder-coated machinery, aluminium extrusion, timber, or anything with a finish, a tensioned steel edge concentrates load along a 0.5 mm line. Edge protectors help. People forget edge protectors.
Cord strap presents a woven face, so the same force spreads across the full strap width. For anything painted, plated or polished, this alone is worth the switch.
Weight and Ease of Handling
A coil of steel band is heavy, awkward, and takes two people to move safely. Composite cord runs at a fraction of the weight for equivalent strength — roughly a fifth, depending on the widths compared.
Practical consequences:
- One person carries a full roll to the load instead of wheeling a coil
- On air freight and LCL, the strapping itself stops being billable weight worth arguing about
- No compressed air or heavy sealer to drag around — cord strap needs a hand tensioner and buckles
- Rolls store on a shelf, not on a stand
Cost Comparison and Total Application Expenses
Per metre, composite usually costs more than the equivalent steel band. Stop there and steel wins.
Don’t stop there. The comparison that matters:
- Steel needs seals or a welding tool; cord needs a buckle
- Steel needs edge protectors on most finished goods; cord usually doesn’t
- Steel generates damage claims from rust bleed and edge cutting
- Steel generates injury incidents, and incidents have costs that never appear on the packaging invoice
- Cord strap is lighter, so freight-billed weight drops
- Cord buckles are frequently reusable; steel seals never are
Across a shipping programme the total application cost typically lands 30–50% lower with composite. On a single pallet, steel looks cheaper. Exporters who ship containers, not pallets, work this out fast.
System Strength Comparison
| Width | Composite system strength | Typical steel equivalent |
| 13 mm | 485–500 kg | 13 × 0.5 mm band |
| 16 mm | 650–700 kg | 16 × 0.5 mm band |
| 19 mm | 900–1,100 kg | 19 × 0.6 mm band |
| 25 mm | 1,400–1,650 kg | 25 × 0.8 mm band |
| 32 mm | 2,000–2,300+ kg | 32 × 0.9 mm band |
Composite matches steel across the working range for cargo securing. It’s the retained tension after a week of vibration where the gap opens.
When to Use Steel Strapping
We’d rather tell you this than have you find out.
- Hot cargo. Steel coils, castings, forgings or billets strapped above roughly 80 °C. Polyester softens. Use steel.
- Aggressive chemical exposure. Sustained contact with strong solvents or specific acids. Check compatibility; steel is often the safer default.
- Sharp unprotected edges under high tension. Cord strap abrades. Sheet metal stacks and unedged profiles will saw through it. Use corner protectors — or use steel.
- Rigid-frame applications where you specifically want zero give and the load will never settle. Rare in export, common in some fabrication work.
Everything else — machinery, timber, pipe, drums, bricks, tiles, palletised goods, container lashing — composite handles better.
Frequently Asked Questions
Is composite cord strapping strong enough to replace steel on heavy machinery? Yes, up to the strength range shown above. A 32 mm system at 2,000–2,300 kg covers the majority of machinery and container lashing applications. Above that, or on a load with a single very high point force, run the calculation before switching.
Does composite strapping need a special tool? A hand tensioner, and that’s it. No welder, no compressed air, no sealer. The wire buckle does the holding, so the tool only applies tension. Training takes about ten minutes.
Will customs or the shipping line accept composite strapping? Yes. Polyester composite cord strap with wire buckles is standard practice for container lashing and export bundling, and it doesn’t carry the ISPM-15 questions that come with timber dunnage.
What about reuse? Cut the strap — never reuse tensioned polyester. The galvanised wire buckles are frequently reusable if the jaw hasn’t spread. Steel band and seals are single-use, full stop.
Does composite stretch too much for rigid loads? Working elongation is low single digits and it recovers. The stretch you get is the stretch you want — it absorbs shock instead of transmitting it into the cargo. If you genuinely need zero movement in a rigid frame, that’s one of the cases for steel.
Summary
Steel is rigid and cheap per metre. Composite holds its tension, doesn’t rust, doesn’t cut, and costs less across the whole shipment. For export cargo that vibrates for weeks and settles as it goes, tension retention is the property that decides whether the load arrives intact. Choose on that, not on the per-metre price.
If you’re currently running steel and you’re not sure what the switch would cost you, send us one cargo configuration. We’ll spec the composite equivalent against it.
Amass Strapping Solutions has manufactured composite cord strapping, container lashing strips and matched galvanised wire buckles from Rajkot, Gujarat since 2012. Strap and buckle are rated as a system, 13 mm to 32 mm, so what you calculate is what you get.
Request a sample roll and a like-for-like comparison against your current steel spec → amass-strap.com