To use a strapping tensioner and sealer, wrap the strap around the load, clamp the lower end in the tensioner, feed the upper end through the tool, and work the lever until the strap is tight. Then place a metal seal over both layers, crimp it with the sealer and cut off the excess.
Last updated: November 2026
That is the whole job in two sentences. The rest of this guide shows each step in detail, which strap and seals the tools work with, and how to fix the usual problems. The tools themselves are in our strapping tools range: a tensioner for 19mm heavy duty strapping and a crimping tool for 19mm metal seals.
What do you need before you start?
You need four things that match each other: the strap, the seals, a tensioner and a sealer (also called a crimper). In the QIS range, the tools are made for one combination: 19mm heavy duty black strapping with 19mm metal seals.
- Heavy duty strapping, 19mm: black, 1,000 metres in a dispenser box, 400kg breaking strain.
- 19mm metal seals: carton of 1,000, rated to 400kg.
- The tensioner, which pulls the strap tight.
- The crimping tool, which folds the seal so it locks both layers of strap together.
Lighter blue strapping does not need tools. It is tightened by hand and held with a buckle, which our guide on how to use plastic strapping covers.
Which strap goes with which seal and tool?
Only the black 19mm heavy duty strap uses the tensioner, crimper and metal seals. The blue straps are hand tensioned with buckles. This table is taken from the compatibility chart on our strapping product pages.
| Strap | Breaking strain | Fastener | Tools needed |
|---|---|---|---|
| 12mm poly (blue) | 95kg | Plastic buckles 12mm | None, hand tensioned |
| 15mm poly (blue) | 140kg | Plastic buckles 15mm | None, hand tensioned |
| 19mm poly (blue) | 200kg | Metal buckles 19mm | None, hand tensioned |
| 19mm heavy duty (black) | 400kg | Metal seals 19mm | Tensioner and crimping tool |
If you are strapping cartons and light bundles, the 19mm blue strapping with metal buckles may be all you need. For pallets and heavy goods, use the heavy duty kit below.
The heavy duty strapping kit
How do you use a strapping tensioner and sealer, step by step?
There are seven steps: wrap, clamp, feed, tension, seal, crimp and cut. Manual tensioners differ a little between models, so check where the gripper, tensioning wheel and cutter sit on yours before the first strap.
- Wrap the strap around the load. Pull strap from the dispenser box, pass it around the load and bring the free end back to the top, where the surface is flat. Overlap the two layers, with the free end underneath and the strap coming from the box on top.
- Clamp the lower strap in the tensioner. Squeeze the tool's handle and base together to open the gripper. Slide the lower strap under the gripper, leaving about 130mm of tail sticking out past the front of the tool. Release the handle so the gripper bites down and holds it.
- Feed the upper strap through the tool. Lay the upper strap over the lower one, pass it through the cutter slot (if your tensioner has a cutter) and into the slot in the tensioning wheel. Pull the slack out by hand so the strap sits snug on the load.
- Tension the strap. Work the lever back and forth. Each stroke winds in more strap. Stop when the strap is firm and does not slide when you push it sideways.
- Place the seal. Put a metal seal, open side down, over both layers of strap just in front of the tensioner.
- Crimp the seal. Open the crimping tool, close its jaws around the seal and squeeze the handles fully together. The seal should be folded hard into both layers of strap.
- Cut and remove. If your tensioner has a cutter, squeeze the handle and base together to cut the upper strap, then slide the tool out sideways. If it does not, cut the strap behind the seal with snips and release the tool.
Give the strap a firm tug once the tool is off. If either layer slips through the seal, cut the strap off and redo it. Do not send out a load on a seal that moves.
How tight should strapping be?
Tight enough that the strap does not move when you push it by hand, and no tighter. Over-tensioning does not make a load safer. It crushes carton edges, cuts into soft goods and puts more stress on the seal.
Two habits help. Put a piece of folded cardboard under the strap at each corner so it does not bite into the top cartons. And use at least two straps on a pallet, one in each direction, so the load is held both ways. For a full pallet going on a truck, strap first, then finish with stretch wrap. Our guide on how to wrap a pallet with stretch wrap covers that part.
What goes wrong, and how do you fix it?
Most problems come from mismatched parts or a strap fed the wrong way. These are the common ones.
- The strap slips while you tension it. The lower strap is not properly under the gripper, or the gripper teeth are clogged. Re-clamp it, and clean the teeth with a stiff brush.
- The seal slides after crimping. The seal and strap are different widths, or the crimp was not squeezed fully. Use 19mm seals on 19mm strap and close the handles all the way.
- The strap twists. It was twisted when it went around the load. Flatten it before you clamp it, because a twisted strap will not sit properly in the seal.
- The strap is tight but the load still moves. One strap is not enough. Add a second strap at 90 degrees, or add stretch wrap.
A drop of light machine oil on the moving parts now and then keeps the lever action smooth.
How do you stay safe when strapping?
A strap under tension stores energy, so treat it with care. Wear gloves and eye protection, keep your face away from the strap line while tensioning, and stand to one side when you cut a tensioned strap, because the cut ends can spring back. Never use strapping to lift a load. It is there to hold goods together, and it is not a handle.
Who uses a tensioner and sealer?
Any business that sends heavy cartons or pallets by freight. That includes warehouses and 3PL operators, transport and courier companies and food producers and manufacturers sending stock out by the pallet. If you only strap a few light cartons a week, hand tensioned strap and buckles from the strapping with buckles or seals range will do the job without tools.
The full strapping range ships Australia-wide, with same-day dispatch on orders placed before 12pm Monday to Friday. You can also pick up from our Archerfield QLD warehouse between 8:30am and 4:30pm on weekdays, or call 1800 555 343 for help matching strap, seals and tools.
Frequently asked questions
Do I need both a tensioner and a sealer?
Yes, for heavy duty strapping with metal seals. The tensioner pulls the strap tight and holds it there. The sealer, also called a crimper, folds the metal seal so it grips both layers of strap. One tool cannot do the other's job, unless you buy a combination tool that does both.
Can I use a strapping tensioner on 12mm or 15mm strap?
Not with the QIS tensioner, which is sized for 19mm heavy duty strap. The 12mm and 15mm blue poly straps are made to be pulled tight by hand and locked with plastic buckles, so they need no tools at all. Match the strap width to the tool and the seal every time.
What is the difference between a strapping seal and a buckle?
A buckle is threaded by hand and holds the strap by friction, so it needs no tools and suits lighter loads. A metal seal is crimped onto both layers of strap with a crimping tool. In the QIS range, seals are rated to 400kg and are used with heavy duty strap.
How do I remove strapping safely?
Cut it with snips or a strap cutter, not a knife blade pulled towards you. Hold the strap down with one hand on the side away from the cut, stand to one side and keep your face clear, because a tensioned strap can spring back when it is released.
How many straps should I put on a pallet?
It depends on the load, but two is a sensible minimum: one in each direction so the goods are held both ways. Tall, heavy or unstable loads need more. For freight, add stretch wrap over the top so loose items cannot work free between the straps.
Can I reuse strapping seals?
No. A metal seal is a single-use part. Once it has been crimped it is bent to shape and will not grip properly a second time. Cut the old strap off, throw the seal away and use a new one. Seals come in cartons of 1,000, so each one costs very little.
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