|Infobox on Marble|
|Example of Marble|
|Stowage factor (in m3/t)||-|
|Humidity / moisture||-|
|Risk factors||See text|
Description / Application
Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock. Metamorphism causes variable recrystallization of the original carbonate mineral grains.
The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the original carbonate rock (protolith) have typically been modified or destroyed.
Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith. The characteristic swirls and veins of many coloured marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone.
Green coloration is often due to serpentine resulting from originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism..
Marble is commonly used for sculpture and as a building material.
See also Limestone or Dolomite.
Shipment / Storage / Risk factors
Marble is notably a very heavy cargo and is offered for transport as tiles, slabs and hewn rocks. Tiles and slabs are normally packaged in timber crating with straw like protection and slabs can also be offered for transport on A frames. Blocks and rocks are presented bare.Marble is notably a very heavy cargo and is offered for transport as tiles, slabs and hewn rocks. Tiles and slabs are normally packaged in timber crating with straw like protection and slabs can also be offered for transport on A frames. Blocks and rocks are presented bare.
Never accept rocks without obtaining detailed information regarding dimensions, shape and weight. Often irregular shaped blocks are offered for transport when in fact they are hewn rocks requiring cradles to support them.
Marble is a soft stone liable to fragmenting under pressure. The stone is partially porous and dirt is easily engrained, reducing quality. The quality ranges are defined by different colours and texture with common colours ranging from black through to brilliant white.
Due to the weight of this cargo and potentially irregular base area (footprint) it is very important to spread the weight over the full area of the container.
Container equipment which in general is used for the transport of marble includes:
Offered in heavy wooden crates up to two tonnes. When loading a chassis mounted container uncoupled from the tractor unit, ensure that chassis pods are not sinking into the yard surface on account of weight. (Asphalt or gravel can be soft when heated).
Crates should be stuffed into the container athwart if possible to allow forklift access. Great care must be taken not to overload the container.
When side loading is being performed ensure side racks or gates can be properly closed and locked without obstruction from cargo. Side curtains must be rolled down at all times to prevent cargo contamination from external sources.
Should be stuffed into container in a fore and aft direction to avoid deceleration during transit (caused by G forces). Crates must always be stowed vertically without leaning on surrounding cargo. Never stow two high without building a false floor of at least 32 mm thickness in between.
Slabs on “A frames” are not suitable for discharging from GP containers.
May be stuffed either on “A frames” or in crates.
Crates must have base battens to allow lifting slings to be attached or removed.
Crates must always be stowed vertically without learning on surrounding cargo. Stowage should be evenly distributed commencing from each side panel and the centre aisle chocked on completion.
When loading onto “A frames” a substantial base must be provided which is almost the width of the container. The frame must be of steel construction, of sufficient strength with appropriate stiffeners and properly welded. Care must be taken to transmit the weight properly over the container floor using timber runners in a fore and aft direction. (This allows weight distribution over the cross members of the container floor).
Even distribution of cargo is required on either side of the A frame.
The cargo must be lashed to the “A frame” independently. This is carried out using timber lathes at intervals along its length and by introducing timber pressure at half height, overall lashings are then applied. Round turns going over the pressure pads hold the stow in position.
The base of the “A frame must also be chocked against the bottom rails of the container using timber chocks covering at least two corrugations at each chock. Vertical movement in transit is prevented with wires/banding placed over the “A frame”/load and secured to lashing points along the bottom rails. (Care to be taken that lashing wires/banding are never in direct contact with the marble, edge protectors to be used).
Roof bows should be applied on completion of stuffing and tilt/tarpaulin fitted and sealed.
When overheight cargo is involved roof bows should be inserted where possible and remaining ones must accompany the container. Either an over height or stand tilt/tarpaulin must cover this cargo. (Standard tilt/tarpaulin must also remain with the container).
“A frames” with slabs are not advisable on flatracks as sufficient cargo protection is not afforded.
Blocks of Marble
Blocks must be placed centrally within the container and eight distributed evenly. This can be achieved using fore and aft timber battens of sufficient strength (minimum 10 x 10 cms). Ensure container payload is sufficient for the intended cargo. Blocks over 26 tonnes are not be accepted for GP stowage and referred for flatrack stowage.
Stuffing of heavy blocks is carried out by carefully landing the blocks, using cranes, onto fore and aft timber battens inside the container. Thereafter by drifting and pushing the block over the battens the required stowage positioning is reached. Discharging is carried out using drag wires attached to a forklift or tugmaster.
Securing of blocks is only carried along the base of the block. (The aim is to prevent initial movement). Here blocks are double stacked the top block must be smaller and chocks and timer are used.
Prior to loading fore and aft timber battens are placed on the container floor. Top loading is performed via a crane. Care must be taken to avoid lifting gear contact with the marble.
(Do not use nylon web slings which stretch and tear). Lashing to be performed as for GP containers.
On completion of loading operations all roof bows to be fitted and tilt/tarpaulin fitted and sealed.
Fore and aft timber battens to be placed on the container floor for weight distribution. Even weight distribution is essential with careful positioning of the block/s onto the flatrack.
Securing is carried out
Fore & Aft: With timber stops across the ends of the flatracks and tombing to the blocks.
Athwart Timber blocks to be fitted into the stanchion pockets a minimum of 30 cms above the floor of the flatrack. This allows timber tombing between them and the marble.
Finally wire lashing/banding is placed over the blocks at regular intervals and fastening to the heavy duty eyes on the flatrack.
Rocks of Marble
Never to be accepted unless they have been dressed and are stowed on a cradle. Stowage and securing as for blocks.
General handling instructions for all marble:
- When handling at terminals care must be exercised to avoid structural distortion to containers given the heavy weight of the cargo.
- Onboard stowage rules are:
1. Close to the centreline of the ship
2. Away from the ends of the vessel. (As close to the tipping centre)
3. Normally no more than four positions above the tank top
4. Where deck stow has to be considered then only first tier to be used