Cargo Work Container Cargo Sea Containers were invented in the mid 1950s by Malcolm McLean, a North Carolina trucking owner who grew tired of wasting his trucking company’s time with trucks standing idle in line as ships were unloaded bit by bit by dockworkers. McLean developed sealed truck trailers and the concept of loading and unloading the trailer interiors only at the points of origin and destination. The first ship modified to accept these “containers” on deck, sailed with 58 of them from New York to Houston in April 1956. This was the start of McLean’s company, the Sea-Land Corporation. The Matson Line (Hawaii) put the first fully containerized ship into service in 1960. The International Standards Organization (ISO) first established container standards in 1961. The ISO standard is not prescriptive and instead simply stipulates tests that the containers must pass. Modern container ships have only one problem – when the ship arrives in port, the object is to unload the containers quickly to get them on to their final destination and to get the container ships back out to sea fully loaded heading for the next port. To accomplish this, container ships are equipped with steel skeletons called “cell guides”. A special lifting fixture is used with remote actuators, which engage the corner blocks on the top of the container. A recent survey indicates that port crane operators can execute full crane cycles to remove and position containers at rates of between 30 and 60 boxes per hour. Containers come in two basic sizes – 20 Footer and 40 Footer and are commonly known as TEU (Twenty Equivalent Units) and FEU (Forty Equivalent Units). The external body of the container is made of corrugated sheet metal and is not capable of taking any load. The four corners have shoes and are strengthened to take in load. Cargo Work and Seamanship II NDT Nautical By Capt Ajantha Pushpakumara Page 1 of 20
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Cargo Work
Container Cargo
Sea Containers were invented in the mid 1950s by Malcolm McLean, a North Carolina trucking
owner who grew tired of wasting his trucking company’s time with trucks standing idle in line as
ships were unloaded bit by bit by dockworkers.
McLean developed sealed truck trailers and the concept of loading and unloading the trailer interiors
only at the points of origin and destination.
The first ship modified to accept these “containers” on deck, sailed with 58 of them from New York
to Houston in April 1956. This was the start of McLean’s company, the Sea-Land Corporation.
The Matson Line (Hawaii) put the first fully containerized ship into service in 1960.
The International Standards Organization (ISO) first established container standards in 1961. The
ISO standard is not prescriptive and instead simply stipulates tests that the containers must pass.
Modern container ships have only one problem – when the ship arrives in port, the object is to
unload the containers quickly to get them on to their final destination and to get the container ships
back out to sea fully loaded heading for the next port.
To accomplish this, container ships are equipped with steel skeletons called “cell guides”.
A special lifting fixture is used with remote actuators, which engage the corner blocks on the top of
the container.
A recent survey indicates that port crane operators can execute full crane cycles to remove and
position containers at rates of between 30 and 60 boxes per hour.
Containers come in two basic sizes – 20 Footer and 40 Footer and are commonly known as TEU
(Twenty Equivalent Units) and FEU (Forty Equivalent Units).
The external body of the container is made of corrugated sheet metal and is not capable of taking any
load. The four corners have shoes and are strengthened to take in load.
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Identification System
Example of an ISO 6346 conform container number
[edit] Owner Code
The owner code consists of three capital letters of the Latin alphabet to indicate the owner or principal operator of the container. Such code needs to be registered at the Bureau International des Containers in Paris to ensure uniqueness worldwide.
[edit] Equipment Category Identifier
The equipment category identifier consists of one of the following three capital letters of the Latin alphabet:
• U for all freight containers • J for detachable freight container-related equipment • Z for trailers and chassis
[edit] Serial Number
The serial number consists of 6 (Arabic) numeric digits, assigned by the owner or operator, uniquely identifying the container within that owner/operator's fleet.
[edit] Check Digit
The check digit consists of one (Arabic) numeric digit providing a means of validating the recording and transmission accuracies of the owner code and serial number.
[edit] Calculation Step 1
An equivalent numerical value is assigned to each letter of the alphabet, beginning with 10 for the letter A (11 and multiples thereof are omitted):
A B C D E F G H I J K L M
10 12 13 14 15 16 17 18 19 20 21 23 24
N O P Q R S T U V W X Y Z
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The individual digits of the serial number keep their numeric value.
[edit] Calculation Step 2
Each of the numbers calculated in step 1 is multiplied by 2position, where position is the exponent to basis 2. Position starts at 0, from left to right.
The following table shows the multiplication factors:
a) Sum up all results of step 2b) Divide them by 11c) Erase all decimal digits of the division (i. e. make the result an integer value)d) Multiply the integer value by 11e) Subtract result of d) from result of a): This is the check digit!
If the final difference is 10, then the check digit becomes 0. To ensure that this does not happen, the standard recommends that serial numbers should not be used which produce a final difference of 10, however there are containers in the market which do not follow this recommendation, so handling this case has to be included if a check digit calculator is programmed.
Notice that step b) to e) mean to find the integer rest of dividing the result of a) by 11. Most programming languages have a modulo operator for this. Attention should be paid on how it is working in the language chosen; i. e. if it is giving back the decimal rest or the integer rest in order to get proper results. - 11 is used as divisor because a containernumber has 11 digits in total. In step 1 the numbers 11, 22 and 33 are left out as they are multiples of the divisor.
[edit] Example
C S Q U 3 0 5 4 3 8 Calc.
13 30 28 32 3 0 5 4 3 8
x x x x x x x x x x
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In day-to-day business it happens that containers do appear which do not follow the ISO 6346 identification at all, however they are fully CSC safety approved containers. Usually these are "shippers owned" containers what means that they are not owned by the carrier but supplied by the cargo owners (shippers). They may have no or no registered owner code and no category identifier and have no check digit. Generally it is not advisable not to follow ISO 6346 as this causes problems to the carriers and container terminals to correctly identify the equipment and to properly deliver the cargo because computer systems require ISO 6346 conform naming and as such missing prefixes are invented, for example YYYY at the carrier and XXXX at the terminal what causes the equipment to mismatch.
[edit] Size and Type Codes
ISO 6346 also gives size and type codes for containers. When displayed on the container, the size and type codes shall be used as a whole.
The codes are compiled of the following elements:
• First character, representing the length (coded) • Second character, representing the width and height (coded) • Third and fourth character indicating the type of the container
The following is an overview of the most common codes:
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45UP HIGH CUBE HARDTOP CONT. 45U6 HIGH CUBE HARDTOP CONT.
46HR INSULATED CONTAINER 46H0 INSULATED CONTAINER
48TG TANK FOR GAS 48T8 TANK FOR GAS
49PL PLATFORM 49P0 PLATFORM
4CGP GP CONTAINER 4CG0 GP CONTAINER (WIDTH 2.5 M)
L0GP HIGH CUBE CONT. L0G1 HIGH CUBE CONT.
L2GP HIGH CUBE CONT. L2G1 HIGH CUBE CONT.
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L5GP HIGH CUBE CONT. L5G1 HIGH CUBE CONT.
Country Code (Optional)
The country code consists of two capital letters of the Latin alphabet as described in ISO 3166. It indicates the country where the code is registered not the nationality of the owner or operator of the container. The letters of the code shall not be less than 100 mm high.
Mandatory Operational Marks
Operational marks are intended solely to convey information requested for the movement of containers or give visual warnings. They relate to
• the weight of containers • a symbol to denote air-surface container • a sign warning of overhead electrical danger • a height mat be for containers higher than 2.6m (8 ft 6 in)
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The inside bottom has a wooden ceiling. There are weather-insulted vents provided to facilitate
venting.
The weights marked on the containers are TARE weight and LADEN weight. TARE weight is the
weight of the empty container and is usually 2200KGS for a TEU, while the LADEN weight may be
anything from 20000KGS to 32000KGS (strengthened steel construction).
The container shoes fitted at the corners are hollow with 5 oval slots to facilitate the fitting of
container fittings as well as for lifting the container – either by using conventional wire slings or by
spreaders.
Since the containers are concentrated weights the loading of the same require special heavy
dunnaging to spread the load evenly over the deck – if carried as deck cargo on conventional general
cargo ships.
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However the carriage of containers are primarily on container ships or on ships, which have been built to take in general cargo as well as containers to a limited extent. Container Carriers
Handling and Safety Instructions
1. Instructions on the proper handling of the securing devices on containers (and other standardized cargo):
- All loose securing elements have to be applied according to this Cargo Securing Manual.
- It is recommended to have only one type of twistlock on board. If more than one type of twistlocks, the different types should be clearly identified.
- All twistlocks in use have to be locked.
- Twistlocks must be inserted so that opening devices are accessible for opening.
- Adjustable pressure- or tension / compression elements have to be set with a minimum clearance to the longitudinal bulkhead in order to reduce the movement within the container block.
- Damaged containers are not allowed to be loaded.
- Cargo carried within the standardized cargo units should be packed and secured within these units. The same principles to stowage and securing of cargo inside the containers should be applied as the same cargo being stowed conventionally onboard.
- The skirts of the bottom rails of the container should not be allowed to come in contact with the underlying dunnage. These structures are not strength members, and will buckle and give way if placed on dunnage.
2. Safety instructions related to handling of securing devices and to securing and unsecuring of containers (or other standardized cargo by ship or shore personnel):
- People working in the cargo area are always to wear a protective helmet and protective shoes.
- Any securing or unsecuring of containers must be carried out during the ship’s stay at berth or safe anchorage.
- Dropping of container fittings from above is forbidden.
- Work on top of container stacks is generally to be avoided. If work on top of containers is not avoidable, an approved fall protection system must be used. Access to the top of a container stack for inserting, locking, unlocking or collecting securing devices is only allowable by means of an approved lashing cage.
- A fall hazard shall exist whenever employees are working within 0.9 meters of the unprotected edge of a work surface and 0.3 meters or more, horizontally, from the adjacent surface. Weather conditions may impair vision or sound footing of workers on top of containers.
- Fall protection systems must be inspected and maintained prior to each day’s use.
- Each fall protection system shall be rigged to minimize the free-fall distance.
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Stowage and Securing Instructions
Possible consequences from misuse of securing devices or misinterpretation of instructions given might result in the following:
- Exceeding the maximum stack mass may result in:- overstressing hatch cover construction- overstressing stowage and securing devices- damaging containers or loss of containers overboard
- When twistlocks are not locked properly this may result in:- overstressing stowage and securing devices- damaging containers or loss of containers overboard
- When lashings are not applied in the relevant places this may result in:- overstressing of twistlocks- damaging containers or loss of containers overboard
- When the weight distribution in the stack is not like prescribed in this manual this may result in:
- overstressing stowage and securing devices- damaging containers or loss of containers overboard
- If the maximum GM - value in the stowage plan is exceeded this may result in:- higher transverse accelerations- overstressing stowage and securing devices- overstressing the ship structure- damaging containers
Stowage and Securing Plan (not included in this model manual)
Lashing of containers on purpose ships are supplied from reputed lashing makers and have been
tested for the loads they are to lash. Various fittings are used and all of these are generally carried on
board.
Base stacker Twist Lock Double Stacker
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Corner Eye Pad Side Stack Thrust Bridge Fitting
Twist Lock Rod Lashing Bar Spacer Stacker
A spacer stacker is used where there is a difference between adjacent containers as loaded in their
heights, one being the 8ft and the other 8.5FT.
On normal ships where these fittings may not be available wire ropes are used however the number
of ropes to be used would be decided by the weight of the container.
On GC ships with no provision for built in shoes only single height loads are carried.
However on container ships the hold stacks may extend to 7 high and on hatch top/ deck to 5 high.
The hold and the deck/ hatch top being strengthened.
The lashings to be done are specified in the container-lashing manual supplied to the ship from the
building yard. This is not to be reduced since the stresses have been calculated and the number of
lashings incorporated.
The containers are loaded onto a container ship in a specified manner. The ship is divided into BAYS
or ROWS. Looking from the side the bays are marked from forward to aft.
The containers are stacked in tiers and are in general called the stacks.
This way ensures that any container can be located very easily – knowing the bay number and the
row number isolates the location and the stack height give the exact position of the container.
On container ships the containers are lowered onto slots inside the holds, the holds bottom is
provided with sunken shoes, twist locks/ stackers are fitted onto these and the container is lowered
onto them.
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Cell Guides on Deck – Open hatch concept:
Some containers are designed to carry refrigerated cargo, these special containers have their own
cooling plant in built on one end of the container, and all that is required for the ship to provide is a
power point for the electricity. The containers come with their own recording device and card, the
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ships officers has to renew the card on the expiry of the same, and is to see that the cooling plant
does not stop functioning, manuals are provided whereby ships staff can do some minor repairs to
the plant.
Today a variety of cargo which previously was thought could only be loaded onto a general cargo
ship, is transported on container ships. An example is a tank, thus small parcels of liquid is carried on
container ships.
Lashing of containers is very important since a typical container ship has a low GM(F), consequently
the ship rolls quite a bit and the stresses developed by the cargo swaying is liable to break the
lashings and put the containers into the sea.
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All lashings are to be done following the ships lashing manual. In general the following is a typical
lashing system, others may also be accepted if permitted by the manual.
The planning of loading of a container ship is normally undertaken ashore, but the officer in charge
of the watch should keep an eye on the loading to detect errors in stowage which may occur. A
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particular watch should be kept for containers with dangerous goods placards to see that their
stowage satisfies segregation requirements as laid down in the IMDG code.
Other things to watch for are that container marked for underdeck stowage do not end up on deck –
this is serious since the container may be for second port by rotation, also the heavier containers are
generally loaded underdeck to increase the GM. Thus in addition to a loss of GM the ship would also
have a mess up at the disport.
Refrigerated containers should be loaded where they can be connected to the ship’s power supply
and the duty officer is to ensure the same. While loading a slight slackening of watch can become a
liability since the gantries load very fast and to unload or to shift is expensive and time consuming –
even if the fault actually is of the port.
Sometimes containers are loaded which due to the nature of the contents have to be overstowed, in
this case the container is loaded and the container is then blocked off so that there would be no
chance of any pilferage – such containers may carry – currency/ coins, drugs, and mail or other high
value cargo.
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