Pressure system

This conventional securing system in the past presented the largest group of securing systems in hold and is splitted again in two subdivisions:

Pressure System

Only pressure forces will be transmitted from the container block to the supporting points at the longitudinal bulkhead.

Tension/Compression System

The container block is splitted in two or three separate blocks and both, tension and compression forces will be transmitted into the side structure by use of T/P-Elements.

For the transversal securing system all containers have to be connected by use of double stacking cones in transversal direction. The horizontal forces from the containers which occur in rolling condition will be transmitted from one stack into the next one and at the same time adding up. The resulting force at the outermost stack has to be absorbed at the longitudinal bulkheads. The maximum horizontal force which may be transmitted by the container corner castings is specified in the individual rules of the classification societies (please compare to chapter 1.11). The required number of supporting points is depending on the acting forces in the container block and the allowable support force specified by class. For this reason it can be necessary in some cases not just to use pressure elements between all tiers but also on top by using bridge fittings and especially designed pressure elements.

Very often the transversal securing system is used for securing of 20’ containers which are stowed in 40’ cellguides at 76 mm ISO gap position but also the transversal securing system is the one and only adequate securing solution for multi purpose container vessels without cellguides in holds.

As an option the pressure elements may be replaced by fixed installed pressure rails which are at the same time protecting the longitudinal bulkhead from damage when loading containers.

Tension / compression system

In case that fully loaded containers can not be achieved even if all container levels are supported by pressure elements, it will be necessary to separate the container block. This separation can be realised by using single stacking cones for example in way of ship’s longitudinal axis. The two separate container blocks now have to be connected by means of tension/pressure-elements and corresponding counter bearings to the longitudinal bulkhead.

For larger container vessel with three hatch cover panels it could be an advantage to separate the containers in three blocks. For this reason single stacking cones in combination with pressure adapters should be used in line with the hatch cover split joint. The container block in the middle of the hold will act by pressure force alternately to both sides. The advantage of this system is that the container blocks below each panel can be discharged separately.

When deciding about the type of counter bearing it is important to know which container heights have to be covered because for each combination of 8’6’’ and 9’6’’ container height there must be a possibility to insert the tension/pressure-elements.

Main disadvantage of the transversal stowage system is that loading and unloading of containers can only be made tierwise. It is not possible to have a 40’ stack next to a 20’ stack because this would interrupt the transmission of horizontal forces.