The resolution from the International Association of Ports and Harbors on the safety of maritime containers and their recommendation to the IMO is to be welcomed. There is a fundamental need for the stricter control over the packing of cargo within containers, how they are stowed on-board ships and their declared weights.
The issue of loading too much cargo into containers has been highlighted internationally during the last decade. In 2007, the investigation following the beaching of the MSC Napoli showed that for 20% of the vessel’s deck cargo, there was a difference of more than three tonnes between the actual weight of the container and the declared weight.
It is clear that the responsibility for declaring the containers weight correctly lies with the shipper, a fact that is already recognised in the International Maritime Organization’s (IMO) Safety of Life at Sea Convention (SOLAS), and there is current debate concerning whether the existing regulations can be further strengthened or clarified by the IMO’s Maritime Safety Committee. Further, the shipper’s responsibility is reinforced in international carriage law.
Shippers may say that it is a challenge to make sure that containers are accurately weighed, but in many cases it is relatively simple. From a logical perspective it should be easy to calculate what the weight of the cargo in a container is if the cargo is uniform – the weight of one item multiplied by the number loaded on a pallet, adding in the weight for the number of pallets used, dunnage and the container itself.
That this process has not become the norm is due to 40-plus years of tolerance of weights being estimated or inaccurate. Quite simply, people have allowed it to continue because, unfortunately, no one stakeholder has faced sufficient pain as a consequence of the mis-declaration of container weights or indeed, until recently focused analysis on the issue. There is now general agreement concerning the need for change. The incidence rate of accidents caused by badly stowed or mis-declared containers continues and the industry is taking action.
Container weighing options
Accurate container weights can help guide critical plans regarding stowage, and verifiable load data also serves to ensure worker safety. Lifting containers within an acceptable weight range also prevents accelerated stress on the spreader, thus extending equipment life. But the options to check the weight of the container for the terminal operator is limited as weighing will stop the flow of containers within the terminal. It is at this point where spreader manufacturers step in. Over the years they have come up with some innovative products ‘hidden’ in the twist-locks of the spreaders to measure the weight of the container without interrupting the handling procedure of the container, thus making sure that productivity is not being affected.
RAM Spreaders
RAM’s engineers have considerable experience as initial design work was first carried out during 1988/89 following on with a prototype system fitted to a prototype RAM Intelligent Spreader. Considerable experience was gained from the test program of the RAM twist-lock load system but at that time there was no market demand. Today the situation has changed. Apart from RAM’s own original design there are also several proprietary systems available. RAM is able to fit any of these systems to its range of spreaders. While the industry is interested in the weight of the container, there is also the benefit that the systems can also provide the loadings applied to each twist-lock. RAM’s spreader operating system can collect the data and provide the terminal with accurate data on individual twist-lock performance. This information, coupled with regular visual and NDT checks can potentially mean that the life of twist-locks can be extended. During servicing of a spreader, twist-locks are often removed for examination or maintenance. Since it does not follow that they will be refitted into the same position on the spreader or may even be fitted to a different spreader, a system that can enable easy traceability is also an advantage. Ideally, the twist-locks should have a simple system, not requiring manual intervention where the spreader can identify electronically the individual twist-locks so when data is recorded it can be logged for subsequent updating of total life records. The life of twist-locks can then be tracked and recorded in whichever spreader they are fitted. Over the last 10 years RAM Spreaders has endeavoured to bring new and innovative products to the market whilst broadening its product range from just spreaders to other equipment that can bring major benefits to the terminal operator.
Bromma
Sweden-based Bromma is offering a similar system to that of the French company Lasstec whereby the container weight verification is done from the spreader twist-locks. For container terminals, a spreader-based weighing approach has several key advantages. First, weighing from the spreader twist-locks yields much more accurate information, as container weight precision is greater than 99%. Second, unlike weigh bridges or crane-based container weighing, spreaders weigh each container separately when operating in twin-lift mode. In addition, with a spreader-based approach you weigh containers from the spreader twist-locks without adding any extra operational steps or requiring any extra space or transit lanes. Terminals simply log container weights in the normal course of lifting operations – with a warning system alerting the terminal to overloaded and eccentric containers. Container weight verification during the normal course of terminal operations is a way to accomplish the weighing mission without impairing terminal productivity, and especially at busy trans-shipment terminals. Bromma offers a special technical advantage in its mounting of spreader-based container weight verification technology by mounting the load cell externally, locked with easy access to the spreader twist-locks. This means load sensors may be exchanged independently of the twist-locks. The result of this design advantage is that new load sensors are not needed when twist-locks are periodically replaced. According to Bromma collecting weight data as part of the regular lifting cycle, with no disruption to terminal work flow, will enable ports to stow containers appropriately, prevent worker injuries, and extend equipment life cycles. That is why container weight verification from the spreader twist-locks is becoming so popular.
Strainstall
The latest company that has introduced a new container weighing system for docking cranes is UK-based Strainstall. Although the company is not a spreader manufacturer it has utilised their 45 years of experience in providing industry leading measurement solutions to develop their own container weighing system.
The system is designed for low impact installation and enables operators to view live loadings via an in-cab display or log/transmit data for analysis at a later stage. Various integration options are available, including modification of spreader twist-locks and replacing existing load bearing pins or components with load measuring pins within the existing spreader head block assembly. “This new system means port operators can significantly improve both safety and productivity by allowing crane operators to know exactly what weights they are lifting, enabling vessels to be correctly loaded and by ensuring all containers are charged according to actual weight,” said Scott Cruttenden, Business Development Manager – Industrial Sector.
The system has numerous benefits including simple non-intrusive integration, high accuracy and reliability, optional telemetry versions, numerous output options, view live or store historic data and can be retrofitted.
Conclusion
The port is an ideal place to carry out weight checks, at the in-gate for example or where the container is lifted off the truck or rail chassis. There is a
far lower risk in relation to containers arriving by sea at a port, where the weighing point would logically be the lift-off the ship-to-shore gantry crane. Nevertheless, once a container is packed and sealed at some inland place it is unlikely to be opened until destination. Thus, while the best place to verify weight clearly is at the outset of the movement, the marine terminal stands at a key nodal check-point in the supply chain. A weight-checking regime of this sort raises three questions in particular: firstly, what is the port supposed to do with a container where the weight differs from what is declared or that is eccentrically packed? And secondly, do governmental enforcement agencies have sufficient resources to follow through new legislation and establish such checks, assuming there is an agreement at the IMO level on the issue? Thirdly, and perhaps the most important one, who is going to pay for it all?