Cargo Work
Bulk Cargo (Grain)
Loading and Stowage of Bulk Grain
Before loading bulk the following preparations should
be done:
Holds and tween deck thoroughly swept down.
All dunnage removed from cargo spaces or stowed at one
and covered.
Bilges should be cleaned and sweetened
Bilges suctions should be tested
Tween deck scuppers should be covered with double
weave separation cloth, edges to be fixed with cement.
Any cracks between limber boards to be covered with
separation cloth nailed down to prevent the cargo from going into the bilges.
All pipelines passing through the bilges should be
tested and any leaks discovered should be fixed – esp. fire mains, water
ballast lines and bilge pumping out lines.
After the holds are swept and if required hosed down,
the holds/ compartments are to be inspected for any infestation.
The inspection should include all easily accessible
areas together with inaccessible areas including under the beams and hatch
pontoon frames. In case fumigation is carried out prior loading then the
compartment has to be swept and again inspected for any dead insects and
rodents. The fumigant used should be compatible with the cargo to be carried.
For loading of Rice the fumigation may be carried out
twice – prior loading and on completion of discharging.
The inspection for infestation should be very thorough
since apart from later claims, some ports especially in the
Shifting of
cargo
Certain bulk cargos have a tendency to shift and
precautions must be taken to counteract this tendency. These precautions are dealt with below:
Recommendation are made about the stowage of the
cargo:
Weight = db (3L+B) tonnes
4.6
where d is the summer load draft
b is average breadth of lower hold
L is length of lower hold
B is the maximum moulded breadth
The height of the cargo pile peak should not exceed:
1.89 x d x S. F. (m3/tonne) metres
Angle of repose
This is the greatest angle from the horizontal to
which a substance can be raised without it shifting. Cargoes most liable to
shift are those having a small angler of repose.
Angle of repose of 35˚ is taken as being the
dividing line for bulk cargoes of lesser or greater shifting hazard and cargoes
having angles of repose of more or less than this figure are considered
separately.
Trimming
In compartments entirely filled with bulk grain the
grain shall be trimmed so as to fill all the spaces between the beams and in
the wings and ends. In compartments
partly filled with bulk grain the grain shall be levelled whenever practicable.
The provision of a shifting boards or longitude
bulkheads within 5% of the vessel’s moulded breadth from the centre line or two
or more longitudinal bulkheads or shifting boards with a distance between of
not more than 60% of the vessel’s moulded breadth. In the latter case suitable sized trimming
hatches are to be provided in the wings at intervals of not more than 7.62m.,
the end hatches being not more than 3.66m from transverse bulkheads.
In holds the shifting boards must extend downwards
from the deck at least 2. 44m or ½ depth of hold whichever is the greater. In ‘tween decks and in feeders, unless there
is some exemption they must extend from deck to deck. If the compartment is only partly filled with
grain, the shifting boards must extend from the bottom of the compartment to at
0.6m above the surface of the bulk grain, however no shifting boards are
necessary if the bulk grain does not occupy more than ½ of the hold or ½ of the
hold where there is a shaft tunnel.
The Shifting boards must not be less than 50mm in
thickness and are to have a 80mm housing at the bulkhead. They must be adequately supported by wood
minimum size 250mm x 50mm or metal uprights with a maximum spacing of 3.96mm
and set in 80mm housings top and bottom.
The jointing of 50mm shifting boards must overlap by at least 230mm in
way of the uprights.
If the uprights are made sufficiently strong and the
length is not too great, shoring or
staying may be unnecessary. If wood shores are used they must be in a single
piece securely fixed at each end and heeled against the permanent structure of
the ship, but not directly against the side plating. The angle between the
shore and the horizontal should be kept as small as possible and must never
exceed 45˚.
The size of the shore is dependent upon its length; a
shore over 6.1m in length would be at least 200m x 150mm. If stays are used
they will be fitted horizontally and will consist of 75mm – 6 x 12 galvanised
flexible steel wire rope, secured with 25mm shackles to uprights and frames and
fitted with 32mm rigging screws in accessible positions.
If the uprights are not secured at the top, the
uppermost shore or stay is to be not less than 0.46m from the top.
The vertical spacing of the shores or stays is
obtained from tables in the rules.
GM
If a GM after correction for FSC of not less than
0.31m is maintained throughout the voyage in one or two deck ships or 0.36m in
other ships longitudinal bulkheads or shifting boards are not required in the
following positions, (except when linseed in bulk is being carried therein)
Below and within 2.13m of a feeder which contains not
less than 5% of the quantity of grain in the space it feeds, but only in way a
hatchway,
In feeders as above provided that the free grain
surface will remain within the feeders throughout the voyage allowing for a
sinkage of 2% of the volume of the compartment fed and a shift of the free grain
surface to 12˚,
In way of the hatchway where the bulk grain has been
saucered, provided that the hatchway is filled with bagged grain or other
suitable bagged cargo. The minimum depth of the bagged cargo in the centre of
the saucer to be 1.83m below the deck level. The grains to be stored tightly up
to the deck head in the other parts of the compartment,
In way of a hatchway in a compartment partly filled
with bulk grain.
The surface of grain in a partly filled compartment is
to be saucered with a minimum height of 1.52m of bagged grain or other suitable
cargo over the portion where there are no shifting boards and 1.22m where there
are shifting boards. This latter height is also required when the bulk grain
does not occupy more than 1/3 of the hold or ½ of the hold where there is a
shaft tunnel.
The bagged grain shall be carried in sound bags, which
shall be securely closed and well filled. The bags or other suitable cargo
shall be supported on suitable platforms which consist of strong separation
cloths with adequate overlapping or 25mm boards spaced not more that 100mm
apart laid on bearers not more than 1.22m apart.
Feeders are to be fitted to feed compartments entirely
filled with bulk grain, except in deep tanks not over ½ moulded breadth of vessel
in case ‘GM c’ above.
They are to contain not less than 2% of the quantity
of grain carried in the compartment, which they feed. The boarding may be
horizontal or vertical but must be sufficiently supported by binders, shores or
stays as laid down in the rules. Feeding holes are to be provided about 0.61m
apart in coamings, which extend more that 0.39m below the deck. The diameter of
the hole is 50mm or 88mm depending on coaming depth. Feeders are assumed to be
capable of feeding a distance of 7.62m.
If any part of the compartment is more that 7.62m
(measured in a fore and aft line) from the nearest feeder, the grain in the
space beyond 7.62m is to be levelled off at a depth of at least 1.83m below the
deck and the space above is to be filled with bagged grain or suitable cargo.
Loading two
different cargoes in the same hold
Very occasionally, different types of grain are loaded
into the same hold. The heavier grain is loaded first and trimmed level over
the entire area of the hold. The surface is covered with separation cloths/
canvas, allowing for ample overlaps, at least 1m. The cloths are carried well
up the sides and ends of the compartment so that the next grain loaded will
force them against the plating between the frames and stiffeners, it has to be
ensured that adequate leeway is allowed for the separation cloth being taken up
the sides and ends of the compartment, since the lower cargo would settle down
during the voyage and if this leeway is not allowed for the cloth would exert a
pull and tear off from the side moorings. This would result in the cargo being
mixed.
The lighter grain should be loaded carefully at first
to avoid displacing the separation cloths. Once the lighter cargo has been
leveled off to a height of 0.5m all over the loading may begin at the usual
rate, care being taken to see that it is constantly leveled by adjusting the
loading chute inflow direction.
When bulk grain is carried in the ‘tween deck of a two
deck ship or in the upper ‘tween deck of a ship having more than two decks or
above deck the following are to be complied with:
Either the GM shall not be less than that specified in
paragraph ‘GM’ or the total quantity of bulk grain or other cargo carried in
the specified space shall not exceed 28% by weight of the total cargo below the
‘tween deck.
Partly filled deck area in the above space is not to
exceed 93m2,
The spaces which contain bulk grain are to be divided
into lengths of not more than 30.5m by transverse bulkheads, or if not so
divided the excess space – beyond 30.5m is to be entirely filled with bagged
grain or other suitable cargo.
Vessels having a GM less than that specified in
paragraph ‘GM’ are not permitted to have more than two holds or compartments
partly filled with bulk grain wherein the overstowing cargo does not fill the
space to the deck head. Feeders are not compartments and so they are exempted
from this requirement.
Double bottom tanks used to meet a stability
requirement are to be adequately subdivided longitudinally unless the width of
the tank at its ½ length does not exceed 60% of the vessel’s moulded breadth.
A grain-loading plan may be supplied to certain ships,
which may then be exempted from some of the provisions outlined above due to
their special construction (such as tanker and bulk carriers), which prevents
shifting of the bulk cargo. However, the resulting list of the vessel must not
exceed 5˚ if the grain settles by 2% and shifts to an angle of 12˚
from its original position.