Weight Verification

How To Weigh A Container: Container Weighing Options Using SOLAS VGM Method 1

By James Oliver Engineering Manager at Olitek

In five months, all shippers subject to SOLAS requirements will be held responsible for providing the verified gross mass (VGM) of every single container they export. The SOLAS Convention has 170 contracting states, which flag about 99% of merchant ships around the world in terms of gross tonnage. Many shippers have already been declaring container weights, as these are needed by carriers to plan the distribution of load on a vessel. Declaration may reflect an estimation of the actual weight of the loaded container, whereas verification provides proof of its actual weight or VGM.

There are instances of misdeclaration: either out of a lack of proper process and equipment or a lack of honesty. This has led to containers falling overboard from ships and trucks tipping over because they are too heavy or too light, or because the center of gravity is so out of whack that very little influence is needed to topple them. Stacks of CTUs have been known to crash down in terminals because a container much lighter than reported was placed at the bottom, making for top-heavy stacks.

This is why the SOLAS guidelines for VGM reporting specify only two acceptable methods for weighing a CTU:

Method 1:  Weigh (or have a third party weigh) the packed CTU.
Method 2:  Weigh all cargo items and packing and securing materials, and add this to the CTU’s tare weight.

Method 1 is often the initial choice: its apparent simplicity promises shippers that weighing shouldn’t take much time. But note that weighing equipment need to pass standards of accuracy, and should be calibrated and certified according to the host state’s standards. Beyond this is where it can get tricky.

The initial step is to examine the equipment the industry currently uses to weigh containers, and assess their accuracy, convenience, and affordability. Shippers also need to consider that in the majority of ports, shipmasters/planners need the VGM at least 12-24 hours in advance to be able to plan proper stowage and safe distribution of weight aboard the ship.

Here are 5 currently available types of equipment that shippers might be able to use (depending on the regulations in their region) to comply with SOLAS weight verification using Method 1:

1. On-site mobile container weighing services (3rd Party) (Weigh at point of packing)
2. On-site equipment (Weigh at point of packing)
3. Weighbridges (Transport to weighbridges)
4. Spreader twist locks (Weigh at port)
5. Load cells on rubber-type gantry cranes (RTGs) (Weigh at port)

#1: On-site Mobile Container Weighing Services (3rd Party) (Weigh at Point of Packing)
A potential game changer is the development of new technologies that allow a technician to weigh a container at the point of packing using mobile devices. Using an on-demand mobile application or web-based system, a shipper can quickly and conveniently schedule a technician to come to the container location, bring a mobile weighing device, and have the packed CTU weighed — much like ordering a driver for a ride to the shops. Through electronic data interchange (EDI), the weighing device can then provide weight verification certificates to comply with SOLAS legislation.

There are many advantages to container weighing by an on-call third-party provider:

• No capital expense required by the shipper, and no assets to maintain or resources to recruit and manage.
• The service can be provided at the site of packing; thus, if an issue is identified, it can beresolved then and there, rather than off-site where transport and repacking will increase fees and time.
• The cost of the service is similar to that of using a weighbridge, but without the cost of transport and handling.

It is quick. A provider can be booked on demand so the nearest one is dispatched to you, and a container can be weighed in an average of 15-25 minutes once on-site.

 

#4: Spreader Twist Locks (Weighing at Port)
Modern spreader twist locks avoid the limitation of weighbridges and cranes in that they can calculate containers’ individual weights even when operating in twin-lift mode.
The advantage of using weighing systems on spreader twist locks is that, like mechanical loaders, they do not require any adjustment to existing infrastructure. Installation downtime tends to be longer, however, as the system must be installed on all spreaders used together with cranes.
The same risks are present during transit to port: being transported over roads, rails or small seas (for transhipment), and endangering workers and people in its vicinity. There is also the challenge of weight declared in advance for ship planning creating the need for additional time at the port for each container. Additionally, the IMO/SOLAS legislation will make the shipper responsible for these risks, and not the port.

#5: Load Cells on Rubber-Type Gantry Cranes (RTGs) (Weighing at Port)

Load cell systems may be installed on RTGs in the shafts of rope sheaves on the trolley or in the rope anchors. While this system does not require extra space, installation may be complex depending on the availability of drawings and exact measurements of sheaves and shafts.
As with load cells on STS cranes, this system cannot weigh containers individually when carrying them as a stack of two or more. It also needs to be re-calibrated regularly and suffers inaccuracies of 3-5% of full scale. And as with spreader twist locks and other options for weighing at port, the shipper must consider the risk of transporting a potentially overweight CTU, or one with eccentric gravity, over roads or rails, and possibly exposing civilians to danger. With main responsibility for CTU weighing placed on the shipper, one cannot be too careful.

 

Choosing Equipment for SOLAS Method 1 Weight Verification
Apart from the methods mentioned above, load cells and/or weighing systems may be installed on reach stackers, straddle carriers, and container-handling forklift trucks. As their weighing mechanisms differ, their accuracy rates vary as well. Highest accuracy comes with using certified mobile solutions, weighbridges, mechanical loaders with weighing systems, or spreader twist locks.
One paramount question to consider is where to install a weighing system. The best answer is not always obvious: most would try to find a location within the terminal instead of examining the entire logistics chain. The answer must meet these standards if it is to comply with both SOLAS weight verification guidelines and the new CTU Code of Practice:

• It must not come too late in the process so that the shipper can submit the VGM to the shipmaster no less than 12-24 hours prior to stowage on-board the vessel.
• It must allow individual weighing of CTUs to the highest possible level of accuracy.
• It must not cause too much loss of time and productivity; installation must be simple and the system must not significantly change or delay the logistics process.
• The equipment or system must be certified and calibrated as mandated by the International Maritime Organization in the SOLAS guidelines.
• It must not pose a risk to workers and people within the CTU’s vicinity.

The last standard —that of minimising or eliminating the hazard posed by a potentially overweight CTU — is the reason why shippers need to look beyond the terminal to answer the question of where to have a container weighed. After all, responsibility ultimately falls on the shipper when a container’s VGM is wrongly declared, and for any accidents that this may cause.

When in doubt, it’s best to fall back on the CTU Code of Practice to ensure you play your part in reducing risks and protecting people, cargoes, and businesses.