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Tie Your Cargo

This page explains cargo tying, which is an essential part of crane operation.
Not only does learning the correct way to tie cargo prevent serious accidents such as a lifted load falling, but it also leads to higher work efficiency.
Cargo tying consists of three steps: measuring the mass, selecting a sling, and tying the cargo.

1. Measuring mass

If the mass of a load is unknown, calculate a rough estimate by visually checking the material and dimensions of the load.
As this method is prone to have a margin of error, it is important to overestimate mass.
Examples of calculating a rough estimate are as follows.

Square steel (one meter long)

Mass (in kg) → Width (in cm) × Height (in cm) × Length (in cm) × 7.85 (g/cm³)
(7.85 is the density of the steel. You can find density of the material online.)

(Example)
Width 10 cm × Height 10 cm × Length 100 cm × 7.85 g/cm³ = 78,500 g
= 78.5 kg

Square steel (one meter long) — Fig. 1 Square steel

Round steel (one meter long)

Mass (in kg) → Radius (in cm) × Radius (in cm) × 3.14 × Length (in cm) ×7.85 (g/cm³)
(3.14 is the circular constant.)

(Example)
Radius 5 cm × Radius 5 cm × 3.14 × Length 100 cm ×7.85 g/cm³ = 61,622 g
= 61.6 kg

Round steel (one meter long) — Fig. 2 Round steel

Steel pipe (one meter long)

Mass (in kg) → {Outer radius (in cm) × Outer radius (in cm) − Inner radius (in cm) × Inner radius (in cm) } × 3.14 × Length (in cm) × 7.85 (g/cm³)

(Example)
(Outer radius 5 cm × Outer radius 5 cm − Inner radius 3 cm × Inner radius 3 cm ) × 3.14 × Length 100 cm × 7.85 g/cm³ = 39,438 g
= 39.4 kg

Steel pipe (one meter long) — Fig. 3 Steel pipe

Steel plate

Mass (in kg) → Width (in cm) × Length (in cm) × thickness (in cm) × 7.85 (g/cm³)

Width 100 cm × Length 100cm × thickness 1 cm × 7.85 g/cm³ = 78,500 g
= 78.5 kg

2. Selecting a sling

Select suitable equipment according to the mass and balance of the load.
Although there are many types of slings, this section presents two common types.

The lifespan of a sling varies depending on the manner and frequency of use and how much mass it carries each time. In addition, its strength weakens over time as it is used. Make efforts to ensure safe operation by inspecting slings daily and regularly replacing or repairing damaged slings.

3. Tying cargo

Start by determining the center of gravity of the load.
After determining the center of gravity, tie the load with wire ropes.
This section introduces two common tying methods for rope and slings.

Note that, in principle, a single hitch, such as that illustrated below, shall not be used as it is unstable.

Points to note when tying cargo

Observe the following points when tying cargo.

Lift a load directly above the center of gravity for safe work.
If the edges of a load are sharp, use pads to protect the slings.
To move several loads, bundle them before moving them.
Lift a load 5 cm to see if it is balanced at the center of gravity before continuing moving it.