Flexi-bags flexi-tanks

Flexi-bags also called flexi-tanks (single-trip tanks) is a bladder designed to fit in to a 20 feet container.

These are an alternative to ISO tank containers (operated by Stolt Nielsen, Hoyer , Bulkhaul, Interbulk  etc ) for shipment of various types of  oils,  fruit juices, wines, food-grade liquids and nonhazardous chemicals across the world.

Flexi bags are loaded into 20' food-grade, ISO containers for ocean transport. Sizes range from 16,000 to 26,000 litres.

Flexitanks are not an approved form of packaging for the carriage by sea of dangerous goods classified under the International Maritime Dangerous Goods Code.

Flexitanks have been used for the carriage of bulk liquids for over twenty years. However, there has been unprecedented expansion since 2000 with the emergence of single-trip tanks. In the early years, shipments amounted to around 5,000 per annum. In 2006 the total global market had increased to about 120,000 flexitank movements. Annual growth is forecast at between 15% and 20%. Of the present trade, it is estimated that between 15% and 20% of global loads emanate from South America, with the movement of wine and fruit juices being particularly prominent. The flexitank market is divided between equipment suppliers and equipment operators. A particularly dominant equipment manufacturer and operator is Trans Ocean Distribution Limited which has approximately 45% of the global market. Some of the newer entrants include a number of the conventional tanktainer operators, such as Stolt Nielsen Transportation Group and Hoyer Global. There are more than 40 manufacturers of flexitanks worldwide.

Standards for material used in flexitank production: The materials used in the production of flexi-bags have to meet the standards set by US Food and Drug Administration, EU food-grade or German BAG standards. 

As of now, there is presently no agreed standard regarding construction and operation. However, the Container Owners Association (COA) set up a flexitank working group with the inaugural meeting held in Paris on 28 June 2007. The aims include producing a ‘Standard’ and a ‘Code of Practice’ that flexitank manufacturers, operators and container operators can follow. Container operators are concerned that the pressure placed on the sidewall panels can result in them bulging beyond accepted ISO external dimensions and tolerances and permanent deformation can occur. Some operators are so concerned that they will not accept the shipment of flexitanks. Many feel that there should be a limit on how much can be carried in a flexitank.

Advantages of Flexitanks

Product dedicated and therefore no risk of cross contamination

Relatively low positioning costs (in some areas 100 empty flexitanks can be positioned for the same cost as one tank container);

Positioning a flexitank with a capacity of up to 24,000 litres inside a 20ft general freight container enables shippers to despatch about 40% more cargo per container than a drummed consignment, about 50% more than a bottled consignment and about 15% additional payload when compared to a container filled with intermediate bulk containers (IBCs)

Disadvantages of flexitanks:

Products classified as Dangerous Goods under the IMDG Code are not permitted

Pumps are required for unloading;

Greater preparation is required than for ISO tank containers, although ISO tanks require substantial cleaning, especially in food applications

Environmental issues arise in connection with the disposal of used single-trip flexitanks

 The risk of leakage of the full contents; The potential of high costs to clean up spillages; and Dependant upon stowage on board, spillage resulting in the contamination of other cargo.

Summary

Certain flexitank types are widely accepted as providing a quality and economic containment system for nonhazardous products. The entry of tanktainer operators into this market suggests that flexitanks may now be seen as a more credible form of transportation.

Damage to containers can occur either as a consequence of improper handling or from pre-existing damage undermining the structural integrity of the freight container.

During transportation the contents of a flexitank will be subject to dynamic forces that will act upon the structure of the container which could cause damage as well as possibly affecting its stability.

A damaged container does not automatically mean that there has been leakage of the product from the flexitank. To minimise the possibility of a flexitank tank being damaged, careful selection of the appropriate freight container is required. A detailed inspection should be undertaken by the container operator before releasing to the flexitank operator, who must in turn undertake its own inspection before fitting their equipment. Flexitank operators should provide clear written advice regarding container selection and the loading of their flexitanks. This guidance should be fully understood and followed. A container carrying a flexitank should be properly labelled to indicate that the contents are a bulk liquid and caution should be exercised in its handling.

Resource: Courtesy UK P& I