Episode 57: Dunnage bags in trucks – the correct way to use them

What does the CTU code say?

The use of dunnage bags in containers is a common method and has become an integral part of the repertoire of securing methods.

The CTU Code devotes an entire chapter to dunnage bags in Appendix 7 Annex 4 and refers exclusively to sea containers, ignoring trucks altogether. It therefore seems appropriate to shed light on the subject and explain the advantages and risks. Reference should also be made to the section 48 “Loading of dunnage bags”.

General information

In general, dunnage bags are used to close existing gaps between loading units and to transfer the resulting acceleration forces of the load to the fixed superstructures of the means of transport without interruption.
For the application, it is important to know that a dunnage bag can only absorb and transfer forces over its entire surface.

First of all, a few basic notes on positive locking, as this is often discussed in different ways in the loading community. The term tight fit comes from connection technology and means the fixed, not freely movable connection of two components. In load securing, the term tight fit is used when the load is stowed in such a way that there are no gaps to the load-bearing superstructures.

The practitioner knows that gaps cannot be avoided, but how big can they be? That is why the regulations allow a certain uncritical gap sum, depending on the means of transport. For trucks, this can be illustrated with the following graphics.

However, the main problem is the load units, because in many cases they are not packed in such a way that they form a block with the basic dimensions of 1.2m x 0.8m. They are often over- or under-built, have gaps between the individual packages or do not fit snugly into the means of transport for other reasons.

The chemical pallets in the CP series deviate from the Euro dimensions, with the exception of the CP-2. In addition to the Euro pallet, there are many other variants, not to mention the special pallets.

It is precisely in these situations that dunnage bags could provide a solution. Of course, there are a few boundary conditions to consider.

1. Dunnage bags can adapt flexibly to uneven surfaces, but these surfaces must be static. If a load unit gives way or swerves when the dunnage bag is filled, it cannot fulfill its purpose and cannot prevent load movements.
2. If a truck with a tarpaulin body is available for loading, the dunnage bags can only be positioned between the load units. But not between the load and the tarpaulin, because the latter gives way. In the case of a box body, this would not be critical.
3. Care must also always be taken to ensure that dunnage bags do not press against sharp edges. Extreme care must also be taken with damaged pallets to avoid damaging the cushioning.
4. There is a risk that the padding will work its way up out of the gap during transportation, particularly in the case of pallets with a base. This can happen in particular if the dunnage bag is too large or too high. It should be dimensioned so that it is under no circumstances higher than the load unit against which it rests.
5. Sometimes the right cushion is not to hand. Filling the gap with two pads that press against each other is an absolute no-go.
6. It is also a no-go to position the cushion in such a way that it presses against locking beams, clamping boards or other securing devices. Dunnage bags always belong between the load.

A few examples

The inclined reader can see that, taking into account the boundary conditions, the dunnage bag in the truck sector is definitely justified.
Stay tuned, the next episodes with interesting topics are coming.

Yours, Sigurd Ehringer