Over the years the merchant shipping has had experience of several serious incidents involving containers shifting.
Most problems arise with containers loaded on deck, and this is not surprising as under-deck stowage is often in cell guides(There are a number of container vessels operating today with cell guides fitted on deck.)
Deck cargoes are exposed to the elements and greater transverse forces, and there are numerous things required of the carrier if deck carriage is to be successful (which also means there are numerous things that can go wrong).
Apart from deck stowage being the most common factor involved with shifting containers, the consequences of shifting on deck can be particularly wide ranging and costly.
Damage may be caused to the shifted container or other units contacted, and where this involves toppling from a stack, damage may be extreme.
This may be particularly critical if a reefer or tank container is involved. Where adjacent units are affected, a domino effect can result in a number of containers shifting and even being lost overboard.
If numerous containers are lost the vessel may be caused to list and this could lead to further shifting as well as stability problems.
Invariably the contents of lost containers will be a total loss, and added to the cost of this is the likelihood that the shipowner may be required by the State, whose waters may be affected, to carry out search and recovery (or at least pay for it, this will be particularly likely if shipping lanes are affected or there is a threat to the environment caused by the container or its contents.)
The contents of containers may also cause harm to the environment and this may lead to claims for damage to property and/or resources. State penalties and fines may be imposed.
There are numerous factors involved with the shifting of containers carried on deck
and this blog attempts to identify and discuss these.
Defective securing devices -Very often the proximate cause of containers shifting is a defect in the securing devices themselves.
Securing devices invariably receive some fairly rough treatment, and this can result in metal fatigue, fractures, breakage, excessive wearing, distortion or other damage.
Rust will readily form under the conditions experienced at sea and this process of corrosion will accelerate the weakening process.
Simple wearing can affect devices such as shoe twistlocks and base sockets to which the former fit. With such devices the edges/lips can become so worn that the twistlock can easily slip out or leave such a small degree of metal to metal contact that the excess clearance allows the containers to move.
Once this momentum is started and excessive loading results, all other securing devices can quickly fail.
Mechanical failure sometimes results from a manufacturing defect and more often than not this is associated with cheaply made devices.
Incompatible securing devices - With the multiplicity of device manufacturers and the lack of standardization, many devices are designed to be used only in conjunction with other devices of the same make.
An example of this is shoe twistlocks which are incompatible with deck sockets.
Another example is the joint use of twistlocks having either right or left handed closing levers.
In such circumstances it is very difficult to tell if the twistlock is closed or open, since in the same lever position one device would appear to be closed and the other would appear to be open. One can imagine how dangerous such a practice is.
Incorrect securing device application -Non-purpose-built containerships are frequently involved with many securing device application problems.
On such vessels steel wires are the common lashing medium, and where bulldog grips are used to either join two ends or form a loop, numerous failures have been found to occur.
Incorrect grip sizes, numbers of grips and improper grip to wire application have all contributed to these failures.
Timber chocking is popular practice on non-purpose-built containerships, principally because it is cheaper and quicker than welding restraints, e.g., I-beams or base sockets (for twistlocks).
Sometimes, however, the chocking is not secure within itself, and shipped seas in particular have a habit of breaking up the chocking arrangement.
Poor lashing angles and leads are yet another example of incorrect securing device application. This is not usually a problem on vessels designed or properly adapted
for the carriage of containers on deck, since the deck/hatch lashing points are positioned to avoid chafing and to be most effective in terms of resisting forces.
A common example of the chafing problem arising on non-purpose-built containerships is loop lashing. This is the bad practice of lashing two adjacent containers with one wire, which passes through the adjacent corner castings of each container. Such a practice may lead to the wire becoming overloaded.
Overloading can also occur where fixed securing devices, like deck eye pads, are made to hold more lashings than they can safely take. Such an arrangement is often associated with poor lashing leads, and accordingly the problem becomes compounded.
The looseness of lashings could be said to be another area of incorrect securing device application.
This can lead to a container or containers gaining momentum as mentioned above. Slack securing usually arises from stevedore/ crew laziness, poor workmanship and/ or perceived/actual time constraints, and such shortfalls are exacerbated when, through poor maintenance, devices are too stiff to operate. Common examples of this are twistlocks left in the not fully closed position and slack turnbuckles.
Of course, securing devices may also work themselves loose during a voyage, particularly in heavy weather.
Understanding a vessel's manoeuvring characteristics is a fundamental requirement for a successful command.
Any misinterpretation or ignorance in this respect can have catastrophic consequences for the master, pilot, crew, third parties and the owner of the vessel concerned.
The wheelhouse poster normally mounted on the bridge bulkhead contains a plethora of statistical information on steering systems, propulsion, squat, turning and stopping distances.
Added to this, a ship handler must also consider external influences of wind, tide, tug and mooring requirements when deciding the best combination of manoeuvring components for the prevailing conditions.
Controllable-pitch propellers and alternative rudder designs also fundamentally alter the conventional handling characteristics of any given hull form.
Although there are significant advantages to be had by the increased flexibility such systems can bring to a vessel’s manoeuvring parameters, it is vital that those responsible for controlling movement are fully aware of how best to take advantage of these benefits and do not underestimate the impact they can have on the vessel’s handling.
For example, applying larger rudder angles to a rudder design fitted with an additional flap on the trailing edge can have a very different effect in restricted and congested waters to using a conventional rudder.
The various types of containers for dry, refrigerated and liquid cargoes have to comply with international requirements for road, rail and sea transportation. In this blog we discuss the most common regulations applicable, and explain how containers are inspected.
ISO standards -
ISO(International Standards Organization.) standards applicable to new containers involve technical recommendations concerning dimensions and tolerances, dealing specifically with the interchangeability of containers on a global scale.
These standards are not mandatory, but are almost universally complied with. The ISO standard 1496 deals with freight containers in general but also covers the different types of containers, such as dry-freight containers, thermal containers and tank containers.
International Convention for Safe Containers (CSC), 1972
(Entered into force on 6 September, 1977. As of 1 June 1998 it had 64 contracting States, representing 62.16 per cent of world tonnage.)
Due to the rapid increase in the use of freight containers and the development of specialized container ships, in 1967 the International Maritime Organization (IMO) started a study of the safety of containerization in sea transport.
In December 1972 the International Convention for Safe Containers (CSC) was signed in Geneva. The aim of the convention was to ensure a high standard of safety for workers during handling and transportation of containers, and also to facilitate international trade by providing uniform international safety regulations.
The CSC made the approval of new containers mandatory and was a welcome means of regulating the construction and safety of containers.
The convention set out procedures for the safety approval of new containers, to be enforced by the States party or organisations authorized by them. The evidence of approval, a Safety Approval Plate, was to be recognised by all when granted by a State party, a system which would allow the containers to move with a minimum of safety control formalities.
It is of interest to note that the CSC was not introduced for the safety of the cargo carried in containers, but for the safety of the persons working around them.
The role of the Classification Societies - The Classification Societies were already engaged in container certification when the CSC was introduced. Most contracting governments chose to authorize these Societies to approve the design, inspection and testing of new containers.( A pioneer some thirty years ago, Bureau Veritas is still a world leader in certification.
of containers, with a market share of 60 per cent of all types of new container approvals, and a similar share for re-certification of tank containers. The rest is largely divided between Lloyd’s Register and American Bureau of Shipping. Both Bureau Veritas and Lloyd’s Register play an important role in the inspection of tank containers. Other Class Societies may have been delegated authority by the various governments, but have only minor world market shares.)
CSC Safety Approval Plate - The CSC Safety Approval Plate is a permanent, non-corrosive, fireproof plate, required to measure no less than 200mm x 100mm. It contains information about the country of approval, approval reference, date of manufacture, manufacturer’s container identification number, maximum operating gross weight, allowable stacking weight for 1.8g(g=9.8 metres/square second, acceleration due to gravity), transverse racking test load value, and may also indicate the end and side walls strength if required. The plate also has room for the month and year of the first examination of new containers and for subsequent examination dates.
The CSC requires the container to have an approval reference on the Safety Approval Plate. For instance, the approval reference “GBLR 8653 975”, means that the container is certified by Lloyd’s Register under authority of Great Britain, 8653 is the approval number and 975 is the date of the approval, i.e., September 1975.
The reference “F/BV/6028/97” means that the approval (number 6028) was provided by Bureau Veritas under authority of the French government in 1997.
Certification of new containers - Certification, carried out by the Class Societies to satisfy requirements of the CSC, will normally include:
– Factory approval (approval of production facilities for mass production to needed quality)
– Design type approval (review of drawings and specifications and testing of prototype)
– Survey of production units (verification of compliance with approved type during production)
– On line and final inspection (random verification of workmanship, production tests, and final inspection of each individual unit or of units selected at random)
Class Societies will usually place a sticker with their logo on the container door, confirming that they carried out the initial certification of the container at the factory.
The sticker is only a marketing element; it has no function in the approval or maintenance of the container. The all important proof of compliance with the CSC is the Safety Approval Plate.