The use of flexitanks for transporting bulk liquid cargo has grown rapidly over the last decade, and this has been projected to continue with perhaps 15% per annum, reaching 1 million shipments in 2018. Products carried include wine and other foodstuffs, traditionally supplemented by latex and dispersions. The latter, together with newer products such as base oils, edible oils and chemicals, can cause problems if a failure occurs in the supply chain and regulators are concerned.

Two new IMO documents will come into force over the next two years which will have an effect on liquid cargo carried in bulk within flexitanks in general purpose containers. While distinct in their objectives, they combine to strengthen the regulatory net around part of the unit load industry that has seen significant growth.

The impact of the CTU Code

The first document is the IMO/ILO/UN ECE Code of Practice for Packing Cargo Transport Units (CTU Code), which includes a section referring to Liquids in Flexitanks and two important requirements:

• The transport of dangerous goods (DG) in flexitanks continues to be prohibited; and
• When a flexitank is loaded into a general purpose CTU, the mass of the liquid in the flexitank should not exceed a value agreed with the CTU operator, to prevent the CTU from suffering bulging damages

The growth into the movement in flexitanks of chemical and edible oils presents a problem, as many of them may be considered as Class 9 dangerous goods, such as fatty acids. Reluctance of shippers to use the 'Proper Shipping Name' for such commodities, as it would preclude them from carriage in flexitanks, would be disturbing. Correct classification of commodities, together with use of appropriate packaging and adherence to other regulatory requirements, is necessary if manufacturers and suppliers of flexitanks are to take a rightful place in the supply chain market.

"Correct classification of commodities is necessary if manufacturers and suppliers of flexitanks are to take a rightful place in the supply chain market"

Unlike PAS 1008 (see TT Talk article) there is no maximum cargo mass or volume included in the CTU Code. Instead, the responsibility is placed on the 'CTU operator', being the owner or operator of the CTU. Many flexitank operators will adopt the PAS limit of 24,000 kilo and 24,000 litre, but without constraints the CTU Code permits the CTU Operator to designate smaller or greater values than stated in the PAS. Smaller could adversely affect the commercial viability of the shipment, while larger may place unacceptable forces on the container and the dynamic load increase instability of the container during handling and transport.

There is no requirement in the PAS for labelling the container and in the CTU Code only a requirement to mark the container on the left hand door. Handlers and transporters may thus not be aware that the container is carrying a flexitank - better practice might be to mark all four vertical surfaces. Additionally, there is no requirement anywhere to indicate the mass or volume of the liquid carried. Thus, where the specific gravity of a liquid is less than 1, larger volumes may be carried. This would have the effect of raising the static centre of gravity, but may not substantially increase the dynamic forces. In fact, safety may be more compromised by loading a flexitank at substantially less than its nominal capacity.

Method to verify gross mass

It has been argued that limiting the size of the cargo by mass alone, rather than also by volume as in the PAS, allows greater control and complies with the second piece of IMO regulation - the amendments relating to the verification of gross mass in SOLAS (the Convention for Safety of Life at Sea). These will - from July 2016 - require that all shippers provide a verified gross mass for all containers either by way weighing the packed container or by calculating the gross mass.

However, the guidelines set out in the IMO Circular MSC.1/Circ.1475 limit the types of cargo that can use calculation (Method 2) in sub section 5.1.2.2:

"Certain types of cargo items (e.g. scrap metal, unbagged grain and other cargo in bulk) do not easily lend themselves to individual weighing of the items to be packed in the container. In such cases, usage of Method No.2 would be inappropriate and impractical, and Method No.1 should be used instead."

This effectively means that containers carrying bulk liquids in flexitanks can only have a verified gross mass produced by Method 1 - weighing the packed container. Accurate measuring equipment supporting the container will permit the packer to control the filling process up to the maximum permitted - and would seem to be in the interests of packers and shippers both commercially and in compliance with international law.

"Containers carrying bulk liquids in flexitanks can only have a verified gross mass produced by weighing the packed container"

Conclusion

Regardless of commodity classification or mass/volume issues, ensuring that the container system is suitable must not only take account of the flexitank and restraining system - the container is equally as important. Selecting one that is fit for purpose and safe to use, free from sharp protrusions and clean cannot be carried out with a cursory glance. CTU operators and packers have a joint responsibility to check thoroughly that the container is suitable and that the flexitank and restraining system fits.

PAS 1008, the CTU Code and the SOLAS amendments should improve safety in flexitank operations, but further steps may be required to ensure this packaging type is adequately regulated as a reliable and efficient system that provides cost effective and safe transport of bulk liquids in general purpose containers.

We gratefully acknowledge the assistance in the preparation of this article of Bill Brassington of ETS Consulting.

We hope that you have found the above interesting. If you would like further information, or have any comments, please email us, or take this opportunity to forward to any colleagues who you may feel would be interested.

We look forward to hearing from you.

Peregrine Storrs-Fox

Risk Management Director, TT Club