|18.104.22.168 Granite curbstones in box containers|
|When packed in box containers, granite counts as a "heavy" cargo, since its stowage factor is such that the container's volume cannot be fully utilized. Depending on volume and payload, the volume-to-payload ratio of 20' containers ranges from approx. 1.2 - 1.8 m³/t. The stowage factor of granite is around 0.36 m³/t, i.e. a container can only be filled with such cargoes to between a fifth and a third of its volumetric capacity. Depending on the unitization of the granite articles, their shape and any wooden props or wooden interlayers used, this value may increase to approximately half the container volume.
The granite is bundled on squared lumber underlays using high-strength steel wire. The wires themselves are guided through holes drilled in the ends of the squared lumber. The bundling and packing method used favors the use of forklift trucks and load transfer to the container floor. Since the tied-on wooden underlays lie lengthwise, the admissible line load cannot be exceeded. The load is thus well distributed over the bottom cross members of the container. Small stowage gaps can be filled with lumber.
If the ends are sharp, boards or wooden sheets should be inserted between the container wall and the granite. The same applies if airbags are inserted at sharp-edged ends, but is unnecessary in the case of straight hewn granite.
Gaps to be braced with airbags should not be much larger than approx. 20 cm. To achieve uniform weight distribution, the stone packages should be packed alternately in groups. A group should correspond approximately to the length of an airbag. It must be ensured that the airbags cannot slip out in an upwards direction,
a problem which can be prevented by using boards and/or wooden sheets to produce inverted "funnels" which are open wider at the bottom:
Such a packing method is not advisable. The container floor is loaded unfavorably, since the tied on wooden underlays extend parallel to the bottom cross members of the container. Forklift trucks can only be used at right angles to the underlaid lumber. Since the bundling was not intended for this, however, considerable damage may occur during packing and unpacking. Damage to the bundles is inevitable. Such packing would theoretically be possible if additional wooden supports and interlayers were used. However, if the container is carried lengthwise (fore and aft stowage), even the smallest of gaps would be sufficient for the rolling motion of the ship to deform the bundles.
The curbstones shown are around a meter in length, making the following packing pattern easily achievable:
The bundles are packed to the left and right against the side walls using upright wooden dunnage. The "aisle" left in the middle is secured with wooden bracing consisting of boards and squared lumber. The squared lumber is positioned at the level of the respective "seams".
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