Steel, PET or polyester strapping?

What does a strap actually do?

A strap holds a load together by putting tension on it. That tension has to survive the entire transport chain — including after the load has been lifted, shaken, stacked and cooled down. Three properties do the heavy lifting:

Tensile strength: the force the strap can absorb before it breaks.
Elongation: how far the strap stretches under load. Low elongation means a tight, rigid application; higher elongation means the strap can absorb shocks.
Recovery: whether the strap springs back after stretching, so tension is retained if the load settles.

Steel, PET and polyester perform very differently on exactly these three points. That is where your decision is really made.

Steel strap: maximum strength, minimum stretch

Steel strap is the strongest strapping material in the range and barely stretches at all. Where plastic strapping gives under tension, steel simply stays put. That makes steel strap the standard for heavy export crates, machine parts, concrete products and steel sections.

The black-lacquered version is the most widely used: the lacquer layer protects against rust and gives a clean finish. For damp or corrosive environments there is also a stainless steel version.

When should you choose steel strap?

The load is heavy, rigid and will not settle — think metal, stone, timber or machinery.
The load arrives hot (freshly rolled steel, for example) or comes near heat; plastic deforms, steel does not.
You want zero stretch in the strapping, because the load would otherwise tip.

EW or AW: which winding do you need?

Steel strap is wound in two ways, and that mainly determines how you process it. With single winding (EW), also known as European winding, the strap lies neatly layer on layer. This coil format is intended for manual strapping and goes onto a reel or dispenser. With American winding (AW), the strap is wound in multiple overlapping layers. This coil format is specifically intended for automatic strapping machines. If you strap by hand, choose EW; if you run a machine, you need AW.

What should you watch out for when handling steel strap?

Steel strap has sharp edges and is under high tension. Always work with proper shears and a tensioner, wear cut-resistant gloves and expect recoil when cutting. On loads with vulnerable corners, place plastic corner protectors under the strap so the steel does not bite into the product.

PET strapping: the plastic replacement for steel

PET strapping is made from polyethylene terephthalate and extruded into a rigid, usually embossed strap. Its tensile strength approaches that of steel while the strap is many times lighter. For many businesses, PET strapping is therefore the logical step away from steel: no rust, no sharp edges, lower transport costs and fully recyclable.

The real advantage of PET lies in its recovery. The strap elongates a few per cent under load, then springs back. If your load settles slightly in transit — which happens with cartons, bagged goods and insulation material almost every time — PET strapping pulls itself tight again. Steel cannot do this: it simply hangs loose once the load shrinks.

When should you choose PET strapping?

The load may settle or expand during transport.
You want to avoid the sharp edges and rust risk of steel, for instance in food and beverage production.
The pallets travel by sea or stand outside temporarily.
You want to cut weight and packaging costs without compromising on load security.

Is PET strapping really as strong as steel?

On paper, the tensile strength of the heaviest PET straps comes close to steel. In practice the comparison is more nuanced: steel wins on absolute break strength and heat resistance, PET wins on retaining tension over time. For a rigid, angular load that will not settle, steel is generally the safer choice. For almost every other pallet load, PET strapping delivers a tighter application on arrival.

Polyester strapping (unistrap): soft, flexible and iron-strong

Polyester strapping — also known in the trade as unistrap — is built up from a large number of fine polyester fibres. That makes the strap soft and textile-like to the touch, free of sharp edges and excellent at absorbing shocks. Polyester strapping is ideal for loads you cannot afford to damage: coated profiles, sanitary ware, plastic pipes, furniture and stacked crates.

Because the strap is unaffected by weather, you can also use it outdoors. Polyester strapping is closed with a metal buckle rather than a seal, which means you need no strapping machine — a hand tensioner is enough.

What is the difference between polyester strapping and PET strapping?

Confusingly, the base material is the same: PET is polyester. The difference lies in how it is processed. PET strapping is extruded into a single rigid, smooth or embossed band. Polyester strapping, by contrast, is woven or bundled from fibres, which keeps it supple and soft. In short: if you decide on rigidity and machine processing, you end up with PET; if you decide on flexibility and product protection, you end up with polyester. For the highest tensile strength in a woven format, also look at woven polyester strapping and composite strap.

When should you choose polyester strapping?

The load is delicate, coated or polished and must not be marked.
The strapping needs to absorb shocks and vibration.
You want to strap without a machine, including on site or outdoors.
You are looking for a strap that is comfortable to handle manually.

The three straps at a glance

Property	Steel strap	PET strapping	Polyester strapping (unistrap)
Material	Steel, black lacquered or stainless	Extruded polyethylene terephthalate	Woven/bundled polyester fibres
Common widths	12, 16 and 19 mm	Narrow to wide versions	13, 16, 19 and 25 mm
Tensile strength (indicative)	approx. 540 – 800 kg	approx. 280 – 760 kg	approx. 375 – 960 kg
Elongation under load	Very low (approx. 1%)	Limited, with recovery	High, shock-absorbing
Tension retention on a settling load	Poor	Excellent	Good
Heat resistant	Yes	No	No
Sharp edges	Yes	No	No
Rust risk	Yes (except stainless)	No	No
Closure	Seal or welding tool	Seal or welding tool	Metal buckle
Machine required	Usually yes	Usually yes	No, hand tensioner is enough
Recyclable	Yes	Yes	Yes
Typical application	Export crates, metal, concrete	Pallet loads, cartons, bagged goods	Delicate and coated products

The tensile strengths listed are indicative and vary by width and thickness. The exact figure per item is shown on the category pages.

Which strap suits your load?

Work through the questions below; in most cases you will have your answer within a minute.

Does your load settle or shrink during transport?

Then PET strapping is almost always the best choice. Its recovery keeps the strap tight while the load beds in. Steel loses its tension in this situation and offers barely any grip on arrival.

Are you shipping sharp, hot or extremely heavy loads?

Then choose steel strap. Plastic deforms under heat and can be cut through by sharp edges. On sharp corners, combine steel strap with corner protectors so the strap does not bite in and tension stays evenly distributed.

Does the load have to arrive undamaged?

For coated, polished or scratch-sensitive products, choose polyester strapping. The soft strap spreads pressure over a larger surface and leaves no marks. Another good option for this application: lashing straps, if you want to reuse the securing multiple times.

Are you strapping light cartons or small parcels?

Then any of these three straps is probably over-specified. For light to medium-duty work, PP strap is cheaper and easier to handle. For bundling cardboard or horticultural produce, also consider sisal and Polypack rope or bale press strapping.

What tooling do you need?

That depends on the strap and on your volume. If you strap occasionally, hand tools are enough: a tensioner and a sealer from our tools range, together with the matching buckles and seals. If you strap dozens of pallets a day, a strapping device pays for itself quickly — it welds the strap without a seal and works considerably faster. Not sure what you need? Our complete strapping sets are a convenient starting point: strap, tooling and closures matched in one go.

Which option is the most cost-effective?

Do not calculate per coil, but per pallet. A coil of PET or polyester strapping often costs less per metre than steel and weighs a fraction of it, saving on shipping and handling. On the other hand, steel can secure very heavy loads with fewer passes. Divide the coil price by the number of pallets it strapped — that is the only figure that counts.

Can you switch from steel to PET strapping?

In many cases yes, but not without reviewing your tooling. A steel strap tensioner and sealer are not suitable for plastic strap, and the seals differ. So always plan a switch together with the matching closures and the right tool. Unsure whether your load suits plastic? Send us your pallet details and weight and we will think it through with you.

Your strapping delivered fast

The full range of strapping materials is available from stock. Ordered on working days before 3:30 PM? Then your order will be shipped the same day. Enjoy free delivery on orders over €75 excl. VAT.

Unsure about the right strap or size?

Do you have questions about which size of strapping straps is best suited to your situation? Please don't hesitate to contact us — by phone on +31 184 – 614256, via info@kortpack.nl or via WhatsApp.

Steel, PET or polyester strapping: which strap should you choose?