Oceangoing Cargo Ships Safety & Operational Matters
Home || Tanker Safety || Container Ship Handling || Commercial Management || EMS ||

How a spreader used to lift containers- Various container handling safety technics

The daily operations involved in a busy container terminal can be termed as one of the most complex environments within the transport sector. Progress of modern container terminals is one of the lifeblood of global trade. Coping with increasing container volumes, the capability of such terminals often comes under pressure. To improve productivity in cargo handling, most terminal operators employ equipment such as straddle carriers and gantries for moving containers into and out of the terminal stack and positioning beneath a portainer crane for lifting onboard the ship.

Cranes must have sufficient outreach to access the containers on the outboard side of the largest ships, which may be stowed up to 24 across. They are fitted with telescopic spreaders so that either 20ft or 40ft units can be lifted easily. Some cranes also fitted with spreaders capable of twin-lifting 20ft containers. Such equipment can usually only operate if containers of the same height are paired. The spreader is fitted with twist locks that enter the apertures in the container's top corner castings and engage when it is turned 90.



containerships operational matters
Oil Tanker Safety Guide
Lifting of a container with ships' gear (by crane or derrick) should properly be carried out using a spreader to ensure that a vertical lift is applied to each top corner casting of the unit. The twist locks of such spreaders may be activated remotely by the crane driver with a sophisticated system or by moving the locking lever on the side of the spreader frame, usually through a rope hanging from the lever. This latter system is referred to as "semi-automatic." The more sophisticated spreader system may also be self-leveling and maintain a parallel line to the ship as the crane, or derrick swings the container on board.

A-container-spreader

An essential spreader may consist of a steel frame with a wide leg and a hook suspended from each corner. The four hooks can be inserted into the corner castings of a container. It works in such a way that the hook protrudes from the casting. It provides maximum support from the seat of the hook and makes for ease of unhooking when the container is in position. It is a slow labor-intensive procedure as stevedores need to be on top of the container or a ladder against the container in order to hook on and unhook. Consequently, it is also an inherently dangerous operation but may be the norm in unsophisticated ports. A container should never be lifted by direct wire slings from top corner castings without a spreader to prevent the wires pinching and thus causing damage to the unit.

Forklift trucks may be used for handling both empty and full containers on terminals/quaysides and when loading/discharging Ro-Ro vessels. Trucks must be capable of handling loaded containers with a mast height suitable for operating within the confines of a Ro-Ro vessel. Lifting with a forklift truck may be by top-lifting spreader, using the forklift pockets or, in some cases, by side-lifting frame, although the latter method is not suitable over uneven terrain. Containers should not be lifted (empty or full) by end frames as this will inevitably damage the container.

Two containers may be lifted together, one on top of the other, by a fork lift truck of adequate capacity in certain circumstances (e.g. the weather deck stowage on board a Ro-Ro vessel with no overhead gear available) to obtain a three-high stow. However, the lifting of two containers, coupled together by twist- locks or similar, by overhead gear is dangerous and should not be attempted unless the system has been properly tested and approved.

container-handling-technics
container handling methods

Container Terminal Operations

With the capacity of some cellular container ships now exceeding 20,000 Teu and exchange of several thousand containers taking place in a particular port, it would be impossible for ship's staff to plan the discharge and loading, taking into account the short turn round time of a ship, constantly changing information, containers arriving up to the last minute, and the requirement for overall knowledge of future container movements (including empties). Thus, planning of the container exchange is normally undertaken by the container terminal under the guidance of a centralized unit controlled by the ship or service operator, which has information available for the whole round voyage and can provide much more effective planning.

Terminal planners are provided with guidelines on the optimum stowage to be planned, taking into account stability, deadweight, port rotation, movement of empties, forecasts of future cargo, and the special requirements of IMDG, out-of-gauge, containerized and refrigerated cargoes. However, planning activity remote from the ship does not detract from the Master's responsibility for the safety of his vessel and the ship's officers must always check stability and stress calculations.

While it is impossible to check all containers being loaded, ships' officers should be alert to the possibility of container damage, the correct stowage position, and labeling of Dangerous Goods containers. The securing of cargo can be seen (e.g., on flat racks), and the declared contents of refrigerated containers should be checked for correct temperature settings. Tank containers should be scrutinized for any sign of leakage or damage to valves. Random checks, either on the terminal or onboard, may provide evidence of any short-comings. Close liaison with shore planners is necessary to up-date stowage positions, weights and, when required, contents, so that stability, etc., can be monitored and checked before departure.

Containers in Non-cellular Ships

The carriage of containers in a non-cellular ship requires much more active input from ships' officers as, unless it is a full container cargo, it is unlikely that shore planners will be involved. While a container may appear to be a substantial unit, care must be taken to protect containers loaded in a compartment with other cargo types, i.e., unitized or breakbulk, to ensure that the doors, roof, and sides are not damaged. If it is necessary to over-stow a container with breakbulk cargo (not a recommended practice) only the lightest of cargo should be used.

Stuffed containers loaded without door seals (or locks) should be queried with the shore staff and a seal fitted with and a note made of the number and the circumstances.

Containers should preferably be stowed in the fore and aft line and be lashed with wire and bottle screws from the top lifting castings to substantial D-rings in the deck unless the ship is fitted with suitable deck twist-lock pockets and rod lashings.

If containers are stowed more than one high, the block of containers should consist of equal height, i.e., avoid mixing 8ft 6 ins and 9ft six ins high containers in the stow, so that an easily secured block is formed. It may be possible to stow a 40ft unit on top of two 20ft units if the position and securing arrangements permit, but two 20ft containers should never be stowed immediately over a 40ft unit unless a specially constructed frame or platform takes the weight.

The weight of a container is supported through its four bottom corner castings, and the calculation of deck loadings must consider this. Some ships are constructed with strengthened points on the deck or the tank-top to support loaded containers. Care must be taken to ensure that they are correctly positioned over these points, and that maximum permitted stack weights are not exceeded.

It is preferable that containers with side canvas tilts, which might be damaged by high winds or heavy spray, are not stowed on the outboard side of the stack on deck. When animals are carried, the stowage position should be such that the crew can gain easy access to them for feeding or watering or, if the worst occurs, for removing an animal carcass at sea.





Related articles
  1. Containership operation : Cargo Securing
    There are six degrees of motion at sea that a ship may have to encounter in a voyage. However, pitching, heaving, and rolling are three major forces that impact most on a containership's lashing arrangement. Lateral rolling motion factors the greatest challenge for piles of containers. If containers are to be carried safely on the deck of a container vessel, they must be tightly connected to the ship. It is done with the aid of devices known as twist locks. .....


  2. Containership operation : Common reasons for stowfall
    Container stows often fail due to container stacks being too heavy and too high overall, exposing the lower containers to excessive transverse racking and compressive forces due to the tipping effect. Such an anomaly may occur if the ship is unable to calculate the forces acting on stow with precision. The Cargo/Container Securing Manual is limited in this respect as the examples of container weight distributions shown may not cover all permutations and eventualities. Software programs have the advantage of taking into account all known variables........


  3. Containership operation: Cargo hold ventilation
    Cargo holds ventilation onboard a containership is very important as it minimizes the risk of harm or damage to cargo. A proper ventilation system assures the quality of the transported goods by preventing the formation of condensation in cargo spaces, reducing the harmful heating of the shipment, and removing potential hazardous gases from cargo spaces........


  4. Containership operation: Safety of personnel
    In port stevedores board the vessel for lashing, unlashing and cargo operations and their safety whilst on board is the vessels responsibility. It is important to understand that any injury caused to stevedores or shore personnel due to a condition on board being unsafe, can result in very large claims to the vessel. .....


  5. Containership operation: wet damage in cargo hold
    When water entered into a ship's cargo, hold it may cause wet damage to the cargo inside containers especially to those stowed on the bottom stack, unless the bilge water is drained in a proper and swift manner. The regular sounding of bilge well or monitoring bilge alarm must be one of the very important or rather essential routine jobs on board. However, this job requires special attention on board. All bilge alarm need to be tested regularly......


  6. Reefer cargo care at sea
    Unlike permanent cold stores or refrigerated ships, where robust equipment is under constant care by qualified personnel, the ISO refrigerated container may travel by several different modes and be in the care of many and varied people. Before being despatched to load refrigerated cargo (usually at shippers' premises), the container and its machinery should be subjected to a rigorous examination.......


  7. Containership cargo stowage and planning
    Master and officers of all vessels require a good working knowledge of the various kinds of cargo they are likely to carry their peculiar characteristics, liability to damage, decay, or deterioration, their measurement, and the usual methods of packing, loading and discharging, stowage, dunnage, etc., as the Master is responsible for the safe loading of his vessel and the proper storage of the cargo......


  8. Stacking Weights Restrictions
    rior loading cargo, stacking weights of containers must be checked against the allowable stack weights on board the vessel both on deck and under deck. Neglecting above may cause serious damage to ships structure, hull and eventually overall stabilty of ship may get affected. Maximum allowable stack weights of Tank tops, Hatch covers and Decks shall not be exceeded at any time......


  9. Lashing strength calculation
    Lashing strength of deck cargo shall be ascertained by using the appropriate lashing strength calculation software where provided. All resulting values for lashing strength must be within the tolerance limits prescribed by the vessels classification society......


  10. Dangerous goods stowage and segregation
    Clear guidelines apply to the stowage and segregation of Dangerous Goods and in some cases may require particular commodities to be carried in completely separate holds. The interaction of two cargoes will not occur if the packaging of that cargo remains intact. However, the Master must always consider the possible effect should the cargo escape for any reason and should not restrict his consideration to those cargoes which are listed in the IMDG Code......


  11. Reefer Container Stowage
    Reefer containers proposed for stowage must be accompanied by a reefer manifest. This reefer manifest should contain Container No., Stow position, Commodity, Temperature, and Ventilation status......


  12. Out of Gauge Container Stowage
    It is essential that, during out of gauge cargo operations, a careful watch is kept for any damage caused to the vessel, her equipment, or to containers. Notice of any damage must be immediately brought to the attention of the Stevedore's representative, the Port Captain/Supercargo and Charterers Agent. Damage reports must be completed in all cases giving the full and comprehensive details of damage caused......


  13. Special Container Stowage
    After receiving stowage plan ships, Chief Officer must ensure that all Deck Officers are aware of any specialized containers due to be worked, such as reefers, vents, over-heights, over-widths, flat racks, etc. and their unique requirements.....


  14. 20 or 40 or 45 feet Compulsory Stowage Locations
    Most cargo securing manual provide a guideline for different container types. These stow positions of 20 feet,40 feet, or 45 feet are also incorporated in a ship-specific stowage planning software and highlight errors if any violations occur......


  15. Irregular Stowage of Containers
    The Terminal Planner shall present the pre-loading plan to the Chief Officer to obtain his approval/comments. The Chief Officer, in turn, enters the cargo data in the loading computer and must ensure that the required criteria, concerning stack weights, trim/stability/stresses/ visibility limitations, DG cargo segregation, and specialized container requirements, are met. He should allow the bunker/freshwater consumption during the voyage and all possibilities of ballasting / deballasting. The completed loading plan must be presented to the ship's Master for approval.....


  16. Over-stow of Containers
    With a closed roof, the hardtop the container offers the same reliable protection as provided by a standard box. Hardtop containers have more lashing points than other container types. This guaran- tees reliable and convenient securing of cargo. .....


  17. Hatch Cover Clearance (High cube containers Under Deck )
    Hatch cover clearance must be checked carefully in case of loading over height containers or high cube containers underdeck......


  18. Other matters regarding cargo stowage as necessary
    Bulk products carried in a closed container might include malt, grain, seed, polythene granules, chemically inert powders, brake fluid, detergent, fruit juice, wine, non-hazardous oils, sodium silicate, fatty acids and maple syrup amongst many others......


More Information

Details Of various Container Types

Safe navigation in a seaway

Hull strength & stability requirement for containerships

Cargo cranes operation, maintenance & safety matters

Cargo stowage and planning in containership

Cargo care at sea

Containership hull strength and stability

Securing arrangement in containerships

Cargo securing in containership requirements

Safe cargo operation in containership

Containerships cargo carrying advantages










Other info pages !

Ships Charterparties Related terms & guideline
Stevedores injury How to prevent injury onboard
Environmental issues How to prevent marine pollution
Cargo & Ballast Handling Safety Guideline
Reefer cargo handling Troubleshoot and countermeasures
DG cargo handling Procedures & Guidelines
Safety in engine room Standard procedures
Questions from user and feedback Read our knowledgebase
Home page




ShipsBusiness.com is merely an informational site about various aspects of ships operation,maintenance procedure, prevention of pollution and many safety guideline. The procedures explained here are only indicative, not exhaustive in nature and one must always be guided by practices of good seamanship.

User feedback is important to update our database. For any comment or suggestions please Contact us
Site Use and Privacy - Read our privacy policy and site use information.
//Home //Terms and conditions of use

Copyright © 2015 www.shipsbusiness.com All rights reserved.