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part2cargocare

By Bertha Carter,2014-05-10 02:00
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part2cargocare

PART 2 CARGO CARE

    CARRIAGE OF STEEL CARGOES

SECTION 1 Loading and Stowage

    SECTION 2 On the Voyage

    SECTION 1 - LOADING AND STOWAGE

     Planning

    It is important not to allow loading to begin before a stowage plan is agreed. Stevedores may be in a hurry to start. They might have to wait, but by approving the stowage plan before the beginning of loading, the Master can avoid worse delays later and prevent damage to cargo, his ship and the lives of those on board.

    If a Surveyor is attending, he should assist and advise the Master in checking the stowage plan.

    Loading wet cargo

    Wet cargo in a ship's holds increases humidity in the air and vapour pressure. The presence of wet cargo in the holds will therefore lead to moisture damage to cargo that was sound and dry on shipment.

    Rain during loading

    Category A packed or wrapped products must not be left uncovered on the quay or loaded during rain.

    Category B non-packed or non-wrapped products will often be stored on the open quay and loaded during light rain. This is usually acceptable provided they are not going into the same hold as dry products.

    A suitable descriptive clause (for example "Wet before Shipment") should be prepared for insertion on Mate's Receipts and Bills of Lading for any wet cargo. Watch out for coils that appear to be dry on the outside but which drip water from the windings when lifted.

    Hatch covers and all other deck openings should be closed in good time to stop rain getting to cargo in the holds.

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    A careful note of the timing of any rain and of the opening and closing of hatch covers should be made so that the Master can check that the timings in the Statement of Facts presented to him for signature match the timings in the ship's log.

    Incompatible cargoes

    Care should be taken not to load incompatible cargoes (such as chemicals, fertilisers, sulphur-bearing materials and, in many instances, hygroscopic cargoes) in the same compartment as steel cargo.

    Strength of tank tops

    Bundles of reinforcing bars and bundles of small scantling materials can be stowed in tween decks. Unpalletised steel coils must never be stowed in

    tween decks. The ideal stowage position for steel products is in the bottom of the vessel, on the tank tops.

    Steel is a high density, deadweight cargo. The danger of tank top overload

    must be considered and avoided. The Master should calculate the

    permissible tonnage and this figure should never be exceeded. The permissible tonnage is calculated as follows:

    Area of tank top (M2) x Tonnes per M2 tank top strength limitation. The tank top strength limitation figure is supplied by the shipbuilder and approved by the Classification Society. The figure usually remains unchanged throughout a ship's life. The strength of the scantlings of the component parts of a ship reduces over the years. The older the ship, the more caution should

    be exercised in calculating the permissible tonnage - a greater safety margin should be left for older vessels.

    If the permissible tonnage is exceeded, the tank top plating may be deformed. In order to spread the pressure evenly over the tank top and thereby reduce structural deformation, dunnage should be adequately spread, this to avoid spot overloading.

    Stowage and lashing of different types of products

    Steel coils

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    No. 1 Hot rolled steel coil provided with steel channels to prevent edge damage

No. 2 Cold rolled steel coil

    In coils of up to 15 tons, the tank top should be dunnaged with two double lines of 6"x1" (15cm x 2.5cm) dunnage wood boards. For coils of over 15 tons, three

    lines of such dunnage should be used. In order to achieve tight stowage and prevent movement, wooden chocks must be inserted on top of the lines of dunnage in the lower tier.

    For handling steel coils, chains and wire rope slings should never be used. The safest lifting gear is a round steel pole through the centre of the coil, or a "C" hook.

    The correct method of stowing hot and cold rolled steel coils (except for

    palletized coils) is usually with their centre cores fore and aft. If they are stowed any other way, they are more likely to shift. Steel coils must never be

    stowed in tween decks, except for palletised coils in special circumstances. If it can be avoided, coils should not be stowed in a single tier, unless they are overstowed with other cargo. If there are only enough coils for a single tier and nothing can be placed on top, an ideal stowage would be to stow the coils in

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    two tiers at the after end of the compartment. If single tier stowage cannot be avoided, each athwartship tier must be secured with a locking coil. As a general guide, the following weight/height ratio should be applied - 10 ton coils: 3 high

    15 ton coils: 2 high

    15+ ton coils: 1 high

    The age of the vessel and strength of the tank tops should be considered, and a lower ratio applied if appropriate to a particular vessel. Begin stowage against the end bulkhead in the centre and the wings, with the gap between the wing and centre stowage closing to leave a space for the insertion of locking coils. The stow should be arranged so that the second tier locking coils do not protrude down into the cantlines of the lower tier by more than one-third of the diameter of the locking coil.

    Ideally, the athwartships lines of cargo should extend out to the extremities of the cargo hold. If stevedores are not equipped with the necessary gear to do this in the upper tiers, a mobile crane can be used to put the outer coils in place.

    Drawings "A" and "B" (see next page) and photographs "3" and "4" show the recommended method of securing with strapping bands. Passing bands

    through the cores of adjacent coils prevents fore and aft movement. Crossing bands over the top of coils prevent up and down movements, when the ship is pitching. This method also stops individual coils from

    turning in stow.

    When you have a single tier, the locking coil should be secured as shown in drawing "C".

Drawing A

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Drawing B

    No. 3 Steel coils recommended securing

    No. 4 Steel coils recommended securing

Drawing C

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    (1) The wire is led through the centre of coil "B" from front to rear side. (2) The end is then passed upwards at the rear side and through the centre of coil "A".

    (3) It passes back downwards on the front side through the centre of coil "B". (4) The wire then passes upwards and diagonally over the top of coil "A" to the front where it is passed downwards.

    (5) It passes through the centre of coil "C".

    (6) It then emerges at the rear side. Passing up and through the centre of coil "A";

    (7) It continues back down again at the front side through the centre of coil "C". (8) At the rear side the wire is taken upwards diagonally across the top of coil "A" to be connected to the opposite end of the wire where it is joined with a span screw.

    Drawings:

    Courtesy of LLP Limited from the publication Steel - Carriage by Sea - 2nd edition by Arthur Sparks MNI.

    Steel strapping bands should always be tightened with pneumatic tools never

    by hand operated tools. The ends of the securing bands should always be joined with two crimp seals.

    Metal strapping bands should ideally be used to secure steel coils, for the following reasons:

    - Each coil can be efficiently secured through its core to the two coils

    beneath - costly perhaps, but the safest method.

    - Using a pneumatic tightening tool, bands are tensioned up to 2,000 kgs. - Bands are applied singly, making it easier to handle them and pass them through awkward gaps.

    - Tension is uniform throughout the stow. (Do not use securing timbers, which defeat this purpose.)

    If wire rope is to be used to secure steel coils, the following precautions should be taken:-

    - All bulldog grips should be properly fitted and adequately tightened.

    - Three bulldog grips should be fitted either side of the span screw. - The turnbuckles should be extended to the maximum of thread before application of the wires in order to ensure that after tightening not more than 1/3 of the thread is used. This will allow for further tightening. Bands/wires should be passed as in Drawings A and B.

    Steel slabs

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No. 5 Steel slabs awaiting shipment

    Mild steel slabs are relatively thin rectangular blocks of steel, weighing up to 20 tons per piece. A popular size can be 6500mm x 1200mm x 250mm with a specific gravity of 7.85; such a slab weighs 15.3 tons. Steel slabs are the basic material from which most steel products are manufactured. Slabs are usually stored in the open - unusually: for steel products, wetness and rust staining is of no consequence.

    The traditional stowage method has been to load slabs with their longitudinal axis athwartships, right out to the ship's sides over and above the sloping plating of the hopper tanks. Dunnage was inserted between each tier, to allow re-slinging for discharge. Building out to the ship's sides produced a staggered stow, more stable than a uniform pile. With a part load, the best stowage position was thought to be at either end of the hold, close to the bulkhead. Such cargoes are now usually carried in bulk carriers, of between 20,000 and 40,000 tons deadweight for full cargoes. In a 30,000 ton ship, the tank tops of the main holds would be about 16m wide. In such ships, the traditional stowage method would produce an unacceptable amount of broken stowage, or loss of space, in some areas.

    This can be avoided by combining traditional athwartships stowage with fore and aft stowage. Complete fore and aft stowage is acceptable in some cases, provided the stow is built out over the hopper tanks. It is particularly important with steel slabs always to remember one of the basic principles of good stowage: to interlock the individual blocks, like building a brick wall. Non-interlocking stacks should be avoided if at all possible. All gaps in the uppermost horizontal tier should be secured with suitable sized timber. As stevedores are able to load heavier and heavier weights, methods of stowage have been devised in which the stevedores simply lower large single loads and stack them in the hatchway square, leaving large gaps at the sides

    and sometimes at the ends of the holds. These methods of stowage are not recommended and should be avoided for the reasons explained above. It may

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    sometimes be acceptable, but only in vessels with box-shaped cargo compartments.

    The danger of tank top overload should always be borne in mind and avoided by reference to the permissible tonnage and by use of suitable dunnaging, when possible.

    Hot and cold rolled steel in packages and bundles

No. 6 Bundles of hot rolled steel sheeting

No. 7 Hot rolled steel in bundles

No. 8 Cold rolled steel sheeting in packages

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No. 9 Cold rolled steel sheeting in packages

    Cold rolled steel sheets are wrapped and referred to as packages. Hot rolled steel sheets are unwrapped, in bundles. Packages usually measure about 1m x 2m x 15cm, weighing about 2,000 kgs. Bundles are of more variable thickness and therefore variable weight.

    These products should be stowed right out to the ship's sides with their longitudinal axis athwartships. No gaps should be left between the edge of the stow and the ship's sides/hopper tanks. Packages/bundles usually have bearers, either longitudinally or transversely. If the bearers are transverse and the units are placed athwartships, as they should be, two lines of 6"x1" single dunnage boards should be inserted to tie the stow together and keep it level. If the tank top is not entirely covered, the "brow of the stow" i.e. the gap between the end of the stow and the bulkhead(s), or adjacently stowed cargo, must be secured, to prevent movement in a fore and aft direction. Dunnage can be laid on the tank top as appropriate.

    Before commencement of loading, 16mm wire cables should be laid fore and aft, about 3m apart. When loading is completed, a 6"x1" board lattice

    fence is fitted to the face of the stow. The securing wires on the tank top are then brought up over the stow to be attached with a span screw to the opposite ends, and then tightened. Gaps between the top layer packages/bundles are

    secured by wedging and/or tomming.

    Single plates

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No. 10 Single hot rolled steel plates awaiting shipment

    Single steel plates are usually quite long and, although heavy, they lack rigidity because of their length. If they are not handled and stowed carefully, they may become kinked.

    Single plates are ideally stowed in the same way as steel slabs. Suitable lengths of dunnage should be inserted between each tier of plates or tier of lifts of plates. The dunnage must be kept in line vertically, close enough together to stop the plates bending, where there are gaps between dunnage.

    Plate-type hooks and clamps are used to secure the wire legs to the plates and are usually attached to a spreader.

    Structural steel

    No. 11 Structurals: hot rolled steel beams or joists stored on the open quay

    Structural steel products are usually shipped in bulk carriers. Beams and

    channels commonly sustain crushing and deformation damage. This can be avoided by placing the products carefully and correctly, and by proper dunnaging.

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