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Cargo Work
Cargo Care
Inspection
of Holds prior Loading:
All holds should be inspected prior commencing loading
this may be done while the ship is enroute or just after completion of
discharging and prior loading at the same port.
A thorough cleaning of the hold is undertaken; the
bilges are cleaned and tried out with an amount of water. If required the hold
is hosed down and the water pumped to holding tanks.
This ensures that there is no refuse lying within the
holds and that the bilges after loading would if necessary be capable of being
pumped out.
The bilges if with offensive smell have to be
sweetened.
This is again a necessity to prevent any food cargo
from being tainted.
All other lines in the hold are to be pressed up and
checked for leaks. Air pipes and sounding pipes passing through the hold spaces
are to be checked up with a head of water.
The above ensures that ingress of water into the hold
is minimized.
The hold bottom has to be inspected for any dents in
the plating.
Some DB’s may be dedicated for fuel oil/ ballast as
such this would give a fair idea if the plates have set in or if their appears
to be a deep indentation/
All spar dunnage at the ship sides are to be fitted
and the frames at the sides have to be inspected.
This is done so that if bale cargo is loaded the
shipside steel does not come in contact with the cargo.
The used lashing material has to be removed including
all temporary eyes, which had been made.
And if this is not done then the same eyes may be
inadvertently be used for new lashing – lashing wires are for one use only and
the risk of parted lashing arises by using old lashings.
Use of Dunnage
There are basically a few reasons why dunnage is so
necessary on general cargo ships while loading general cargo.
Of prime importance is to keep the cargo away from the
steel bottom of the hold. The steel bottom condenses the moisture in the air
and these droplets of moisture over a period of time can damage cargo. This is
known as ship sweat. And only by dunnage can the cargo be safeguarded against
this. Good ventilation certainly helps but some amount of sweat is ever
present.
The second reason why dunnage is spread about on the
holds is to bring about some amount of frictional resistance between the cargo
and the steel bottom. Thus lashing becomes easier. Another factor is the
dunnage helps in spreading the cargo weight evenly.
In the event of small ingress of water the dunnage
helps in channeling the water into the bilge wells,
if this were not prevented then any accidental ingress of water would be
absorbed or retained in pools by the cargo.
If the hold bottom is dirty due to stain and hard
coating of earlier cargo and hosing down is not possible then a double layer of
dunnage would prevent the cargo in coming into contact with the stain.
In general holds are laid with double dunnage while
tween decks are layered with single dunnage.
The size of the dunnage may vary but usually they are
about 6” X 1” X 6 feet. These are laid about 6” to 10” apart, though the gaps
may again vary depending upon the nature of the cargo. The bottom tier of the
hold dunnaging may be laid in the fore and aft direction and the top tier in
the athwart ship direction. At the aft of the hold a clearing of two feet is
laid with the bottom tier in the athwart ship direction. This helps in the
water/ condensation from trickling to aft and then subsequently finding the
bilge well.
Tween deck dunnaging is of one tier – exceptionally
may be two tiers and it really doesn’t make much difference if the dunnage is
laid out in the fore and aft direction or in the athwart ship direction.
For heavy cargo where spreading the weight takes
precedence over other hazards, the dunnage or timber used is generally 4” X 4”
X 6 feet (they may be also of stouter variety).
These heavy timbers are laid out in the fore and aft
direction in order that the load is spread on as many frame spaces as possible.
Dunnaging also forms a very important factor when
ventilation is of primary concern especially when loading a consignment of
Rice. Extra channels are created within the bagged cargo to allow good
ventilation. Together with double dunnaging being provided between stacks of
4-6 bags. If this is not done then the cargo sweat that may be generated is not
removed and condenses on the cargo itself allowing the cargo to rot.
Dunnage is used primarily for the protection of the
cargo from sweat related damage and consequently it is used so that the cargo
does not get too closely packed thereby obstructing to the flow of air.
Special cargoes use more dunnage where air channels
have to be kept so that the airflow is not hampered. Rice is one such cargo.
Advantage of dunnaging is also from the fact that it
spreads the weight of the cargo evenly all across the tank top or tween deck
top, but this advantage is a side benefit, the main reason is protection from
sweat. And to some extent from heat from the boiler spaces in the engine room.
Dunnage is thus primarily for the prevention of sweat
damage to cargo.
The structure of the ship is made of steel, this steel
being a good conductor of heat cools down faster than wood as such the
temperature of the steel may fall below the dew point of the air within the
compartment leading to sweat. However if this steel can be prevented from
coming into contact with the cargo by a layer of wood, which being a poor
conductor of heat does not cool down so drastically, then the effect of the
sweat coming into contact with the cargo and thus damaging the same may be
limited.
If despite precautions being taken, sweating does
occur, the damage caused may be minimized by adequate dunnaging of the
boundaries of the compartment.
The permanent dunnage of the ships side is known as
SPAR Ceiling or CARGO BATTENS. It consists of timber about 150mm x 50mm fitted
over the side frames. It is usually
fitted horizontally into cleats on the frames. There is a vertical distance of
not more than 230mm between the battens. On some ships the spars are fitted
vertically and this gives better protection to the cargo as well as it suffers
less damage and is thus more long lasting. Spar ceiling may also be fitted on
the bulkheads at the ends of the compartment; this is especially the case where
the bulkhead is the engine room bulkhead.
The tank top should be covered with a double layer of
dunnage. The bottom layer is usually
100mm x 50mm or 150mm x 50mm spaced about 300mm apart and laid athwart ships to
ensure free drainage to the bilges. If the ship has only bilge wells then it is
preferable to lay the dunnage in the fore and aft direction.
The upper layer consists of 25mm boards about 150mm in
width laid at right angles to the bottom layer, about 150mm - 300mm apart.
Occasionally burlap/Hessian is laid over the dunnage -
this improves the appearance of the hold but restricts air circulation through
the cargo,
A permanent wooden ceiling more than 65mm thick is
often laid on the tank top in the square of the hatch; this is to protect the
tank top and does not replace the dunnaging.
A similar arrangement of dunnage will be found in the
tween decks, although double dunnaging is not so commonly found here. Care should be taken to have a good layer of
dunnage at the ship’s side over the stringer plate, as water tends to
accumulate there.
Secondhand timber is frequently used for dunnage. It should always be inspected to ensure that
it is free of stains, odour, nails and large splinters. New timber also has its
drawbacks; it should be free of resin and should not have a strong smell of new
wood.
The top of the cargo is protected by a covering (especially under the stringer plate) by matting, wood dunnage or some sort of waterproof paper, or plastic sheets.
Single Fore and Aft dunnaging the most common
dunnaging:
The second Layer
Contamination of Cargo
Cargoes -which taint easily, e.g. tea, flour, sugar,
should be kept well away from strong smells.
If a pungent (strong smelling) cargo e.g. cloves, cinnamon has been
carried previously, deodorizing of the compartment will be necessary.
Dirty Cargoes should never be carried in the same
compartment as “clean” cargoes.
A very general classification for “dirty” cargoes
could include paints and oils, steelwork, animal products other than
foodstuffs. Similarly a general
classification of clean cargo could include food products and manufactured
vegetable products e.g. clothing.
Naturally there will be exceptions to both of the above groups.
Reasons for a general inspection of holds
All holds should be inspected prior commencing loading
this may be done while the ship is enroute or just after completion of discharging
and prior loading at the same port.
A thorough cleaning of the hold is undertaken; the
bilges are cleaned and tried out with an amount of water. If required the hold
is hosed down and the water pumped to holding tanks.
This ensures that there is no refuse lying within the
holds and that the bilges after loading would if necessary be capable of being
pumped out.
The bilges if with offensive smell have to be
sweetened.
This is again a necessity to prevent any food cargo
from being tainted.
All other lines in the hold are to be pressed up and
checked for leaks. Air pipes and sounding pipes passing through the hold spaces
are to be checked up with a head of water.
The above ensures that ingress of water into the hold
is minimized.
The hold bottom has to be inspected for any dents in
the plating.
Some DB’s may be dedicated for fuel oil/ ballast as
such this inspection would give a fair idea if the plates have set in or if
their appears to be a deep indentation.
All spar dunnage at the ship sides are to be fitted
and the frames at the sides have to be inspected.
This is done so that if bale cargo is loaded the
shipside steel does not come in contact with the cargo.
The used lashing material has to be removed including
all temporary eyes, which had been made.
And if this is not done then the same eyes may be
inadvertently be used for new lashing - lashing wires are for one use only and
the risk of parted lashing arises by using old lashings.
Bilge and Suction Wells
Bilges and bilge wells should be thoroughly cleaned
prior loading any cargo and especially if the previous cargo was oil cakes or
such other cargo.
Bilges should be cleaned, the suctions tried out and
then the bilges should be sweetened with pine oil or such. The bilges should be
finally dried.
Prior loading of cargo all bilge wells should be
cleaned and then filled with water and the water then pumped out.
Timings for pumping out the water should be noted and
compared with the pump efficiency.
While filling the bilge well the sounding as measured
by the sounding rod should be checked against the actual as observed inside the
bilge well.
The sounding pipe should be checked for any blockage.
The striker plate underneath the sounding pipe also
should be checked for wear down.
Deep Tanks
Deep tanks are tanks on general cargo ships, which are
accessible from the hold. The lines leading to such tanks are to be blanked off
since a slight leakage in such lines can damage cargo in the holds. The man
holes to these tanks also has to be ensured that they are water tight. If any
liquid is loaded then the thermometer conduits should be checked for any
leakage as well the heating coils have to be tested prior loading. The pumping
out arrangement has to be tried out before hand.
Covering of Bilge Wells
These suction filters are very easily taken care of.
Hessian is used to form a pad comprising of a double layer and this is wrapped
around the loose filter covers of the drain wells. The pad should not be so
thick that it would absorb water and prevent the water from draining into the
wells.
For limber boards the same pads are nailed down
between the adjacent boards. And they then serve the same purpose, that is
prevent any debris from clogging up the suctions.
Care of Ballast Lines
This is very important, since the inadvertent
ballasting of the deep tanks would damage cargo loaded in the deep tanks.
There are many instances of the above happening, bulk
carriers of yesteryears often had a hold dedicated as a water ballast tank, in
1978 a new ship off the building yard in Gothenburg had not blanked off the
ballast lines since the line had a double segregation. The vessel proceeded to
load grain in a
Separation Of Cargo
Separation of cargo for the above cases is required to
prevent claims arising due to short landing and later complications with port
authorities and customs for cargo left behind on a ship for which duty is
payable
There may be numerous ways of separating cargoes bound
for different ports or for same port and different consignees. In general
though not all are any hard and fast rule the principle is to ensure that
cargoes destined for a particular port or consignee is delivered accordingly.
Failure to do this at the time of loading would create
chaos at the discharging port, with short landings – residual cargo, since the
excess cargo that would remain would not be permitted to be discharged in a
subsequent port without creating more paperwork and expenditure. In fact cases
have arisen where ships have been arrested for landing cargo not destined for
that port – customs take a very strict view of this in many parts of the world.
Thus it is of paramount importance to ensure that
cargoes are efficiently separated and marked so that to an un-initiated the
cargo discharge may proceed smoothly.
Port markings may be made by different means for
different cargoes, the following are some of the few:
Hessian separation strips, in various colours – used
to encircle the parcel
Shoring, blocking and securing the later port cargo,
since this would have to be done in any case at the discharging port.
Paper sheets
Lashing ropes with coloured strips of cloth wrapped
around the joints-turnbuckles/ shackles/ bulldog clips.
Different cargo used as a separation between two
similar cargoes.
Water based colours used as port marking or consignee
marking – this method though is used more often for consignee marking.
Where bare steel cargo is loaded oil based paint is
also sometimes used, since the others may not be suitable due to partial
rusting of the plates as well that hessian strips are in-efficient for these
cargoes.
Valuable Cargo
Valuable cargo such as Banknotes or mail earlier used
to be carried on general cargo ships in special lockers. If such lockers were
not available then some dedicated space, which could be effectively secured,
was made available. Newer ships do not have such allotted spaces and today most
cargoes of such nature is shipped in containers.
Personal effects are also shipped and unless stated as
very valuable is loaded in ordinary holds and are quickly over stowed with
other cargo. As long as the over stowage is incomplete the hold is strictly
watched and the watchman is done away with once the cargo is over stowed and
the entrance to the hold is locked.
All mail and personal effects are tallied on board –
by shore staff as well by a ships staff, the results are then verified. In case
of any dispute the authorities are informed before a general protest is made.
Ventilation
On general cargo ships one of the largest number of
cargo claims is made for goods, which, have been damaged in transit. Barring breakages and handling damage the
most common damage is caused by sweat.
SWEAT is formed when the water vapour in the air
condenses out into water droplets when the air is cooled below its dew
point.
The water droplets may be deposited onto the ship’s
structure known as “ship’s sweat” or on to the cargo known as “cargo
sweat”.
Ship’s sweat may run down, and may also drip onto the
cargo.
Cargo sweat occurs when the cargo is cold and the
incoming air is warm. Cargo sweat that is formed may be absorbed by the cargo or
if steel may run down after rusting the cargo.
To avoid sweat and its effects it is imperative that
wet and dry bulb temperatures of the air entering and the air contained in the
cargo compartment are taken at frequent intervals (once a watch).
If the temperature of the outside air is less than the
dew point of the air already in the compartment, sweating will occur.
This gives rise to ship sweat and is most usually
found on voyages from warm places to colder places. Especially in winter, on
voyages from
Similarly if the temperature of the air in the
compartment (or the cargo) is lower than the dew point of the incoming air
sweating will again occur.
This gives rise to cargo sweat and usually occurs on
voyage from cold to warmer places. Especially in winter, on voyages from
If the latter of the foregoing conditions is
encountered ventilation from the outside air should be stopped until more
favourable conditions obtain.
It should be noted that indiscriminate ventilation
often does more harm than no ventilation whatsoever.
It should also be noted that variation in the angles
of the ventilators from the wind cause very different rates of airflow within
the compartment.
The angle, which the ship’s course makes with the
wind, also affects the flow of air.
In general the greatest airflow occurs when the lee
ventilators are trimmed on the wind and the weather ventilators are trimmed
away from the wind.
Showing air circulation with lee vents on the wind and
weather vents off.
This is THROUGH VENTILATION.
If the dew point temperature of the air in the hold
can be kept below the temperature of the ship’s structure (decks, sides and
bulkheads) and the cargo, there will be no danger of sweat forming.
This condition cannot always be achieved without some
means of mechanically circulating and drying the air in the hold.
With mechanical ventilation baffle plates are fitted
in the hold and tween deck ventilators, so that air can be prevented from the
outside when conditions are unfavourable.
At these times the air in the hold is re-circulated and, if necessary,
it can be dried by passing it through a de- humidifying unit.
It must be emphasized that the best results can only
be obtained from these systems when air temperatures and dew points are
carefully observed and the maker’s instructions followed implicitly.
The adequate ventilation of container cargoes poses
many problems and experiments have been made with portable ventilation units
fitted into the individual containers.
However, it would appear the most common practice is to give through
ventilation for the container compartments and hope that the ventilator grilles
on the side of the containers give the correct flow air over the contents. It may be pointed out that vastly different
types of cargo may be loaded in adjacent containers in the ‘cell’ stowage and
in most cases the ship’s personnel are unaware of the contents of individual
containers.
Refrigerated cargo
The cleanliness of cargo compartments for the
transport of refrigerated foodstuffs is more important than for any other
cargoes. Failure to clean properly can result in mould growth and rotting of
fruit and vegetables. Spaces are swept down and all loose dirt removed. Any
remaining residues of previous cargoes will have to be scraped or washed off.
After cleaning, the spaces are sprayed with a mild disinfectant such as weak
sodium hypochlorite solution, which also helps to remove odours. Alternatively,
an ozoniser may be used for the same purpose, especially after the carriage of
a strong-smelling cargo like oranges.
Holds and lockers are then cooled to carriage
temperature. It is essential that any dunnage to be used is placed in the space
before pre-cooling, since the use of warm dunnage could cause considerable
damage. It is common practice to have holds and refrigerating machinery
inspected by an independent surveyor to certify that the ship is in a fit
condition for the carriage of the intended cargo.
The cargo should be inspected ashore by the ship’s
officers before loading to see that it is in good condition and has been
properly pre-cooled where that is required. A sample of the cargo should be
thoroughly inspected for signs of mould or other damage and its temperature
checked by inserting a steel-tipped thermometer into the product. A record of
the inspection and temperatures recorded should be kept. Similar random
inspections of the cargo should be made during the loading. Any damaged
products or carcasses which have thawed should be rejected or loaded
separately. They could cause spoiling of the remainder of the cargo which was
in good condition.
The carriage temperatures are stipulated by the
shipper of the goods and should be adhered to as closely as possible.
Temperatures are taken and recorded at frequent regular intervals and entered
in a log-book. Many ships are also equipped with thermographs, which provide a
continuous record of compartment temperatures. In the event of claims for cargo
damage, the records and thermograph charts will be required as evidence that
the correct temperatures were maintained.
In general cargo ships with a limited amount of
refrigerated space it is usual to arrange, as far as possible, for the
refrigerated cargo to be loaded last and at its destination to be discharged
first.
When refrigerated cargo is to be,
carried, specially insulated compartments must be provided. The insulation on the sides, top and bottom
of the compartment may be of cork, fiberglass wool or polyurethane rigid foam.
It will be retained in position by galvanised sheeting.
The cooling may be effected by either circulating cold
brine (relative density 1.047) through pipes on the sides and deck head, or by
blowing cold air through the compartment.
The compartment must be scrupulously clean when
loading meat and dairy products. It is recommended that after sweeping out, the
compartment is wiped down with cloths wrung out in a cleansing fluid; this will
prevent the formation of mould on woodwork.
If a fruit or other strong smelling cargo has been carried in the
compartment previously, it will also be necessary to deodorize it. Spaces are
swept down and all loose dirt removed. Any remaining residues of previous
cargoes will have to be scraped or washed off. After cleaning, the spaces are sprayed
with a mild disinfectant such as weak sodium hypochlorite solution, which also
helps to remove odours. Alternatively, an ozoniser may be used for the same
purpose, especially after the carriage of a strong-smelling cargo like oranges.
The bilges should be cleaned and sweetened and their
suctions tested. The brine traps should
be cleaned out, refilled and tested.
This also applies to those in the ‘tween deck.
The brine traps serve a dual purpose they prevent the
cold air from reaching the bilges and thus freezing out the water in the pipes
and also they prevent the bad odour from the bilges reaching the cold chambers.
If the vessel is fitted with brine-pipes the side
baffle boards (which keep the cargo clear of the pipes) should be removed and
the pipes wiped clean. If fitted with
the cold air circulation system, air ducts should be cleaned, this is
particularly important if a dusty cargo has been carried previously.
Any fat or grease spots on the deck should be scraped
up.
The insulation should be inspected and any repairs
necessary to it or to the sparring, which is attached to it, must be effected.
Thermometers should, be made ready and, where fitted,
thermometer pipes should be erected.
Any ventilators leading to the compartment must be
plugged. Air change plugs should also be
in position.
Dunnage must be pre-cooled before use. In most-trades the dunnage will be laid
before the loading commences.
If the compartment is fitted with gratings, these will
have been scrubbed before being laid down.
When chilled meat is to be carried, the requisite
number of meat bars, hooks and chain will have to be placed in the compartment
for pre-cooling.
The hook and chains should be sterilized (this is
usually done ashore).
When the compartment has been prepared it will be
cooled to the loading temperature. It
will then be ready for the surveyor to carry out a loading port survey. In most cases this is in essential before any
cargo is loaded.
When the cargo has been loaded the portable
brine-pipes will be fitted in the. square of the hatch. Afterwards the
insulated plug hatches must be shipped and fitted as tightly as possible.
It is frequently necessary to paste paper over the
joints to keep the hatch as airtight as possible. In extreme cases the joints may have to be
caulked and pitched. In the latter case,
the greatest. care must be taken when opening up as pitch and oakum falling
onto carcass meat can stain it.
When general cargo or frozen cargo at a different
temperature is being carried in the deck above, a layer of sawdust is often put
over the hatches and deck to absorb any condensation.
Occasionally it may be necessary to load cargo through
a ‘tween deck which contains refrigerated cargo. The refrigeration should be
stopped whilst the hatches are open, otherwise an undue amount of frost may
form. If this forms on brine pipes it
will act as insulation and prevent further cooling.
Refrigerated containers with their own built in
cooling units are to be inspected as thoroughly as for chambers above – that is
if they are being stuffed on board, this is extremely rare. In general the
containers are pre-cooled ashore and then are stuffed at the providers place or
in the dock from refrigerated trucks. The inspections are done by shore
surveyors.
Prior loading all the ships power points for these
containers are to be tested and logged down.
While receiving the containers the containers are to
be inspected for any dents or gashes on the body and the temperature card
(circular) is to be noted.
The temperature is to be noted, however the
temperature may a bit high on loading and it comes down after the ships power
is switched on. The temperature graph is to be monitored and any sign of
heating up is to be prevented. Some units have drawings to do some sort of
emergency arrangements if the unit fails during the voyage.
The graph card needs to be renewed once the time scale
gets over and these are kept as spare on board and are to be replaced by fresh
cards, the filled in cards are to be kept with the cargo/ chief officer for
handing them ashore prior discharging.
Temperature records are vital in both the methods of
carriage. Temperatures are to be recorded at least three times a day and all
the points provided and the same is to be recorded, if automatic recorders are
provided then the visual sightings also should be used for checking.
For containers too the same procedure is to be
followed, visual sightings are recorded together with the automatic recording.
All records are to be kept safely are to be handed
over (copies) to the shore authorities after discharging. These records are
vital in case there are claims about the cargo and the temperature records are
the only proof the ship has to refute the claims.
Prior loading the cargo in pallets are to be inspected
(non containerized) by ships officer together with the surveyor. Often the
cargo is brought to the jetty and the packages may show signs of softening
(thaw) these are to be rejected. Also depending on the shippers agreeing the
temperature probes (which may puncture the cases) may be inserted to note the
temperature, this however may not be allowed since they apparently damage the
cases (paper hardboard). Any staining of the cases again is to be investigated
and rejected if necessary. Reefer cargo is loaded last and discharged first.
All cargo is tallied on board and ashore since some are liable for pilferage –
shrimps as such.