Composite Strapping 32 mm: Practical Guide
Lash it tight, ship it safe
The SECAL 32 mm composite strap is the synthetic steel of cargo lashing: high-tenacity polyester with a polypropylene coating that secures your cargo with the strength of steel, but lighter, safer and free of corrosion. This guide shows you how to apply it inside a container, step by step.
1. Why 32 mm composite strap
The 32 mm strap is the widest and strongest in the composite line: the choice for heavy, bulky or high-value cargo that needs maximum lashing tension inside a container. It replaces steel strapping and nailed timber.
2,500 daN system strength
Strap plus C-type buckle together, certified AAR Grade 4 — roughly 2.5 tonnes of restraint.
No rust, no stains
It does not corrode or mark the cargo. It stands up to moisture, sun and outdoor storage, so it suits ocean export.
Lighter and safer than steel
No sharp cutting edges and no dangerous recoil when cut, and it goes on in less time.
2. The system: three parts that work together
A. Composite strap, 32 mm
Polyester yarn with a polypropylene coating. It takes impact without giving: low elongation (<14%) and it recovers tension. Linear strength 1,470 daN.
B. Galvanised C-type buckle, 32 mm
A double galvanised wire frame. The strap folds inside and locks itself by friction — no seals, no crimping. It reopens easily for re-tensioning.
C. Tensioner, manual or pneumatic
Applies the pre-tension. The manual one is portable; the pneumatic gives maximum force with minimum effort for intensive operations.
D. Edge protectors
They redirect the strap cleanly at the corners to change its angle, and spread the tension over a wider surface.
3. Specifications
| Specification | Value | Detail |
|---|---|---|
| System strength | 2,500 daN (~2.5 t) | Strap plus C-type buckle together |
| Linear strap strength | 1,470 daN (~1.47 t) | Break in direct tension |
| Width | 32 mm | 1¼ in |
| Elongation at break | <14% | Low elongation, recovers tension |
| Coil | 230 m | 2 coils per carton |
| Certification | AAR Grade 4 | Suitable for rail and ocean lashing |
Material: polyester yarn with polypropylene coating; galvanised 32 mm C-type steel buckle; recommended tensioner AT40 / ATC40. Shelf life: strap 24 months, buckles 12 months, stored indoors. Tolerance ±10% on strengths and dimensions — confirm the batch certificate with your SECAL adviser.
4. How to apply it
1. Pass
Run the strap under or around the cargo and through the container D-ring. Work from the coil to cut waste and keep control of the tension.
2. Buckle
Feed both ends into the C-type buckle, fold the strap over the centre bar and bring it back. Under tension the strap bites against the wire and locks itself by friction — no seals, no stapling.
3. Tensioner
Pull out all the slack by hand first, then set the tensioner about 25 cm from the buckle. Pulling the slack by hand uses the full travel of the tensioner and reaches maximum force.
4. Tension
Work the tensioner lever up and down, gradually, to keep control. The SECAL signal: when the strap coating inside the buckle begins to peel slightly, you have reached the right tension. That behaviour is what stops you over-tensioning and preserves the impact absorption.
5. Cut
Cut the excess with the tensioner cutter. The buckle holds the tension by friction with no extra tooling. Leave a 5–7 cm tail beside the buckle for safety.
5. Four lashing patterns
Cross lashing — the X pattern
The straps run diagonally from the floor anchor points to the top corners of the cargo, forming an X on each face. The most versatile method, and very good at blocking lateral movement. For palletised cargo, crates, machinery and packages that can shift forwards or sideways.
Harness lashing — the perimeter belt
The strap goes round the cargo like a belt and anchors on both sides of the container. Instead of compressing from above it hugs the block of cargo and holds it together between the walls. For IBCs, drums, sacks and grouped cargo that must not be compressed from the top.
Cross bracing on a full container
When the cargo fills the container, a large X goes over the front face of the whole block, anchored to the floor on both sides. It acts as a crossed barrier that stops the column of cargo coming towards the doors under braking. The best defence against longitudinal shift of the whole mass.
Loop lashing with edge protectors
The strap hugs the cargo and passes over an edge protector at each top corner. The protector changes the angle cleanly, spreads the tension over a wider surface and stops a live edge cutting the strap. Mandatory wherever the strap rubs a sharp edge.
In all four methods: use edge protectors wherever the strap touches a live edge, keep the cargo clear of the doors and never let it rest against them. The doors only work as a wall once the cargo is already properly secured.
6. The calculation: how much of your cargo can actually shift
This is the calculation that settles everything. Not all of the cargo pushes: friction with the floor holds part of it back. What can shift is what your straps have to stop. Work it out and you know exactly how many X patterns to use.
Step 1 — braking force
Under braking the cargo pushes forward with up to 80% of its weight: weight × 0.8. That is the worst case to overcome.
Step 2 — the weight that shifts
Friction (μ) holds part of it. What is left is the shiftable weight: (0.8 − μ) × weight.
Step 3 — number of X patterns
Each 32 mm X resists about 2,500 kg: shiftable weight ÷ 2.5 t, rounded up.
Worked example, 20 tonnes. Braking force: 20 t × 0.8 = 16 t. With μ 0.30, friction holds 0.30 × 20 = 6 t. Weight that can shift: 16 − 6 = 10 t. Number of X patterns: 10 t ÷ 2.5 t = 4 X.
So of the 20 t, friction holds 6 t and up to 10 t could shift. Since each X resists 2.5 t, you need 4 X to stop it.
Reference calculation on EN 12195-1 criteria. Adjust the 0.8 factor for the transport mode and confirm the capacity of the X with your SECAL adviser. For dangerous or critical cargo, ask for the formal calculation.
7. Quick table: how many X patterns
The friction coefficient (μ) is how well the base of the cargo grips the container floor. Reference values, cargo against floor: 0.60 with an anti-slip rubber mat under the cargo; 0.45 dry timber on the container timber floor; 0.30 cardboard on cardboard, or timber on a metal floor; 0.20 smooth, damp or dusty surfaces.
| Weight | μ 0.30 | μ 0.45 | μ 0.60 |
|---|---|---|---|
| ≤5,000 kg | 1 X | 1 X | 1 X |
| 8,000 kg | 2 X | 2 X | 1 X |
| 10,000 kg | 2 X | 2 X | 1 X |
| 15,000 kg | 3 X | 3 X | 2 X |
| 20,000 kg | 4 X | 3 X | 2 X |
1 X = 2 crossed straps. Calculated as (0.8 − μ) × weight ÷ 2.5 t on EN 12195-1 criteria. Spread the X patterns symmetrically over the load face.
A 20,000 kg block on a normal floor (μ 0.30) needs 4 X; the same block on an anti-slip mat (μ 0.60) drops to 2 X. Friction does much of the work, so raising it is the cheapest way to cut the number of straps — the anti-slip mat is the best-value accessory in the system.
8. Frequent questions
How do I know the strap is tight enough?
When the coating inside the buckle starts to peel slightly, you have reached the right tension. Beyond that you are over-tensioning and losing the impact absorption that makes composite strap work.
Does it need seals or crimping?
No. The C-type buckle locks by friction: the strap folds over the centre bar and bites against the galvanised wire. That also means you can reopen it to re-tension.
How far from the buckle does the tensioner go?
About 25 cm. Pull all the slack out by hand first so the tensioner has its full travel available.
Can I use 25 mm components with 32 mm strap?
No. The certified strength applies to matched components. Use 32 mm strap with the 32 mm buckle and the recommended tensioner.
How long does the strap keep?
Twenty-four months for the strap and twelve for the buckles, stored indoors. Confirm the batch certificate with your SECAL adviser.
Does it replace dunnage air bags?
No — they do different jobs. The strap holds each load unit together; the air bag removes the void between units and the walls. Used together they cover both.
Heavy or high-value cargo to lash?
Tell us the weight, the floor and the route and we will work out the pattern and the number of straps.
This guide is a reference. Confirm product, dose and placement with your SECAL adviser according to your cargo and route. SECAL technical guides · PROTEXPO S.A.C. / SECAL, Lima, Peru.