Industrial packagings rising star is a 6,000-gallon plastic bag, fitted into a standard 20-foot shipping container. Known as the flexitank, the market for this bulk liquid packaging option has more than quadrupled in the past 10 years – and sources say that much of the momentum came from the lubricants industry.

In 2005, a total of around 139,000 container loads were sent by flexitank worldwide, estimates Trans Ocean Bulk Logistics, a leading supplier of flexitank shipping services. By 2014, that number had grown to 600,000, and this year it estimates that some 700,000 container units of nonhazardous fluids will travel this way.

Trans Ocean itself moves about 140,000 of those units a year, making it the worlds largest manufacturer and shipper of flexitanks, said Mark Reader, business development manager for the company in Houston. Lubricants are a significant user of flexitanks, he confirmed. Potentially, the market is huge, because any nonhazardous liquid can be handled this way – lubricants, chemicals, personal care, foodstuffs. Were especially seeing growth from lubricant customers who are moving away from drums, totes and ISO tanks for cost reasons.

As he explained to LubesnGreases, With drums, you can only fit 88 55-gallon drums on pallets into a 20-foot shipping container. Thats only about 17,000 liters of actual product, versus 24,000 liters in the same space using our flexitank. If you ship tote bins, you probably can get 18 totes into the same 20-foot container, but thats still just 18,000 liters. So with the 24,000-liter flexitank youve reduced your shipping cost per gallon or per kilo or pound, any way you measure it.

Erica Kurth, an operations manager in Houston with SIA Flexitanks, another seller of flexitank bags that offers loading services, agreed. She said cost savings are behind the growing volumes of base oils, additives, lubricants and transformer oils using this shipping method.

Lubricants are one of the biggest users by far, she related. Its a big business and were almost overwhelmed right now by demand for shipments going out of the United States. Here in Houston we are shipping about 150 to 180 loads a month, with some shipments as large as 30 containers.

The flexitank is an elegant and simple concept: A large, thick plastic or rubber bladder is unfurled inside a standard 20-foot-equivalent shipping container, the floor and walls of which have been padded with heavy corrugated paper. Next, the bag is braced with a bulkhead (usually plastic or metal) to hold it in place. Finally, it is filled with the liquid product through a gate, ball or butterfly valve. After the container doors are closed and secured, the entire unit is ready to travel by truck, container ship or in some cases rail to its final destination, like any intermodal container. Once delivered, the material is drained or pumped out of the bladder.

This is a one-use, disposable and recyclable option, Reader pointed out. Unlike with ISO tanks, theres no need to pay to have the container cleaned or repositioned for its next trip. One of the problems with an ISO tank is that you have to clean it for reloading with the next product, but at some destinations it can be hard to find an ISO-certified cleaning location. If a location in Africa or the Caribbean or South America cant clean the tank, it has to be shipped back to Houston for cleaning. The deadhead return trip and cleaning requirements add cost that are sidestepped with the flexitank, he emphasized.

For finished lubricants, a big advantage for flexitanks is that most of the weight conveyed is actual product – not bottles, jugs, cartons, drums, etc. Those packages can be easily filled at the destination, closer to the final consumer. The wine industry offers an excellent example of the efficiency: Frogs Leap regularly ships wine abroad from California in 24,000-liter flexitanks, a volume equivalent to 32,000 bottles of wine. Were it to use the same 20-foot container to ship cases of wine, it would fit only 16,800 bottles.

Bulk products such as base oils can ship more economically too, versus heavy steel ISO tanks or totes. Ray Masson of the U.K.-based base oil trader Puma Crown, sees growing numbers of cargoes moving via flexitanks, especially from Europe to customers in Central Asia, Middle East, Africa, India and Asia.

Weve done five to 50 containers in a single shipment – thats 260,000 tons – where the material started at an inland terminal, Masson said. They even can be cheaper than using bulk parcel carriers, and on some routes – like Black Sea-to-Far East – they are far, far cheaper than bulk. Bulk is always going to be more efficient if you have terminals at both ends of the route, because flexies do take more handling. But the flexitank goes all the way to the customer, door-to-door, under the normal documents and bill of lading; thats no different. In each case, you have to attest each shipment, or each container.

Typically, he sees base oil moving via flexitank from a suppliers inland storage tank, then on a container vessel to a developing country; the container is then offloaded onto a truck and hauled by road to the customers location for unloading.

We also see a small quantity of flexitanks that serve as storage. Theres demurrage on the container, but not nearly what it is for a tankcar or ISO tank. For example, a receiver in Cote dIvoire might keep a container for a month, which they couldnt afford to do with an ISO tank, said Masson.

Shippers do have to be mindful of weight restrictions on European roads, which mandate a maximum of 20 metric tons, including the containers tare weight, Masson said. You can ship approximately 18 tons of product in a flexitank, or a bit more in the Baltic states, where road limits are greater than 20 tons. In other geographic areas, the weight may climb higher.

In his experience, the effort and equipment required are the same as with any bulk shipment. The bag is fixed inside a frame. Just like with a tank truck, you fill it from the top and discharge from the bottom – often just using gravity alone, although heavy stuff may require a pump.

The one absolutely critical thing, Masson added, is that you must not ever open the container until youre ready to empty the bag.

For a fee, the top flexitank suppliers offer supervised loading, sending a representative to an approved loading site to assure the bag is set up, filled and closed properly. Once they are trained for the process and have several shipments under their belts, many users take on the loading themselves. However, Kurth of SIA said, some transloading plant operators – rail yards for example – require supervised loading at all times when material is transferred from railcars into flexies.

Loading a flexitank is a simple operation, everyone agrees, and takes from one to two hours, depending on the viscosity of the product being pumped in. Every two minutes, 24 hours a day, 365 days a year, a Trans Ocean flexitank is being loaded or unloaded somewhere in the world, Mark Reader said assuredly. If you can load a tanktruck or an ISO tank, you can load a flexitank.

Denny Madden, senior vice president of Amalie Oil Co., which is based at the Port of Tampa, Fla., and has ready access to ships, trucks and rail connections, reported, We have used flexitanks very successfully for about 15 to 17 years now. We probably are shipping an average of one or two per week over a 12-month period. We like them. We have sent them to locations as far away as Australia and China. We most frequently send flexitanks to Chile. We have a very well-trained crew here who set these bags up in the 20-foot containers and send them on their merry way to the far-flung locations.

Over the years we have had very few problems, and our customers who use them seem to like them, Madden continued. If you are good and are conscientious, you can take the used bags apart and a lot of the material may be recycled, too.

Other lubricant blenders are also adopting this packaging and shipping method, hears Annie Jarquin of the research and consulting firm Malik/Pims. Benchmarking studies of lubricant plant operations indicate that it is definitely becoming more popular, she said. Fifteen percent of the plants dispatching bulk finished products now report using flexitanks as one of their methods. Usage is particularly high in port cities such as Singapore, for example, where flexies are filled with a range of products destined for export and marine markets.

On the other hand, Jarquin commented, we were hearing from our benchmarking study customers that they felt it was more difficult. Operationally, our data so far suggests there is no advantage or disadvantage with regard to opex [operating expense]. I think people are still worrying about leakage, etc. – although if using quality flexitanks this should not be a problem.

That big worry – leakage from a burst bag – has not been a problem when flexies are used to ship base oils, Puma Crowns Masson asserted. If properly fitted and loaded, they are absolutely oil-tight. I think its a bigger problem to fill a shipping container with drums, which rub up against each other and develop leaks during a long journey.

Kurth says that most leaks occur when the user fails to secure the lock-down pin on the bladders valve, allowing contents to seep out. You have to check that the pin is locked down, she stressed.

Even so, the whole package makes some uneasy. The ability to securely load into and dispense from flexies requires training. And insurers have voiced concerns regarding overweight shipments, bag integrity, fitness for rail carriage, and added wear and tear on the shipping containers themselves.

None of these are insurmountable issues, says Mark Reader of Trans Ocean – but they do require engineering know-how, rigorous attention to quality and proper handling.

Read more about that, and some innovative uses for flexitanks, in next months issue.