2.4 – Understanding the Load – Containers and other loads using ISO twist locks

ISO shipping containers are fitted with ISO standard twist lock mechanisms which attach to the corner castings on the container which are designed for lifting and restraint of the container.

Container twist lock

Container restrained by twist lock

Click on the video bellow to see how Twistlocks work.

It is also possible to double stack low height containers or other loads using Double twist locks but it is important to establish the weight of the containers and place the heavier container on the bottom to minimise the centre of gravity.

Stacked low height containers

In addition to standards ISO shipping Containers Frames with ISO twist locks are also used to restrain other loads such as small tanks.

Tank restrained with twist locks

Impact of containers on vehicle mass and stability.

Placing and securing the load within containers is critical for the stability of the vehicle and for compliance with Mass dimension and loading requirements. (See Lesson 2.1) and you may not always have control of the loading on the container because it may be sealed and have been loaded by someone else. However, you may still be liable for a breech of Mass Dimension and Loading Regulations.

Accordingly it is suggested that organisations handling containers familiarise themselves with the NHVR advice ‘Managing the risk of transporting freight in shipping containers – Regulatory

If you have control of the loading on the container here are some tips on good practice:

Loading heavier loads at the bottom and light loads at the top can also help; to lower the centre of gravity

Uneven loading along the length of the vehicle may have impact on axle masses. This will be discussed further in lesson 3.1

It is also important that the forces on walls caused by blocked loads and on the floor for any load are within the limits in defined in AS 37114.4 for freight containers and are within the manufacturers’ recommendation for the containers or for the vehicle. It is also important to consider the orientation of the container on the truck or trailer.

The doors on the container are not always designed to deal with the forces potentially caused by braking and if the load is not adequately restrained within the container, they may not meet the 0.8W performance standard for braking. As a result best practice is for the container doors to generally be oriented toward the rear of the vehicle.

Movement of the load within the container can also lead to stability problem. In a similar manner to other contained loads.

Other methods for transporting empty containers

Full containers should only be restrained using twist locks because containers are not engineered to be restrained by other methods when full and tie rail anchor points are not strong enough to restrain full containers.

If an empty container needs to be transported and a vehicle with twist locks is not available, see page 98 of the LRG for recommendations.

See pages 84,85,97-99 of LRG for more advice related to containers

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