Difference between Flexitanks and ISO Tanks for Bulk Liquid Shipping

Posted by: miamiseo
Category: bulk liquid transport, Flexitanks, Other Tanks, Sin categoría

Tank containers and flexitanks both work in transporting bulk liquids. Depending on the product you’re shipping and the intended destination, one method might be preferable over the other.

Depending on the product being shipped, the product’s origin, and the cargo’s destination, the most economical and reliable method of transportation might not be apparent. While both offer an effective means of transporting liquids, some distinct differences exist between them:

What is Flexitank?

Flexitanks are flexible bladders/bags that can collapse and fit into an ISO container and work to store and transport non-regulated liquids. These bags make it possible to ship non-regulated liquids efficiently over long distances either by road, sea, or rail.

The storage container’s walls comprise numerous polyethylene layers. The inner layers comprise flexible polyethylene while the external wall features a stronger interwoven material-polypropylene.

Since its wall is flexible, it needs an external structure for support when it fills up with liquid. By leveraging normal shipping containers, these storage bags offer a healthier, safer, and more cost-effective substitute to customized tankers for bulk liquid transportation.

What is ISO Tank?

The shipping container derives its name from the ISO standard. The tanks work to transport non-hazardous and hazardous liquids. A major distinguishing element of an ISO tank from a flexibag is that an ISO tank is stainless steel-made. The tank’s inner wall is lined with different protective layers to avoid steel corrosion and liquid contamination by reacting with the steel.

The typical design comprises a manhole at the top together with a valve at the top and bottom. You can distinguish them easily by their cylindrical shape and might have a lining to decrease corrosion and wear from the contents.

However, they lack the huge disposable bladder lining that exists in flexitanks. Besides transporting liquid fuel and gas, they can be specially built for food transportation.


ISO containers can carry between 5,500 and 11,600 gallons. Smaller equipment can work for local deliveries and transport less than 3,000 gallons. A flexibag on the other hand comes in various sizes, with typical volumes ranging from 16-24 thousand liters. Nevertheless, small volumes, as low as 10,000 liters exist as well.


Given that tankers are naturally sturdy, the service length of ISO containers is longer than that of flexitanks. ISO tanks can last approximately three decades compared to flexibags, which need disposal after each delivery.


When it comes to transporting bulk liquids, a tanker permits a huge delivery than using numerous flexibags for the same delivery.

Another hurdle originates from orders that don’t need the maximum space accessible. This isn’t an issue when that delivery mode is a food-grade tanker. However, the same can’t be said for a flexitank. In that case, continuous movement from accessible space, also called underloading, could cause a flexibag to burst eventually.

Added Expenses

Since a flexitank is disposable, it doesn’t have a rental fee when using it although you’ll incur a disposal fee. Such rental expenses could add up fast, especially when international shipping is concerned. Furthermore, the charges for an ISO tank that are incorporated into the final price, which can include return assessments and washing, could make what appears like an economical move into a financial error.

Advantages of Flexitanks

20k liter pillow tank


Unlike other storage equipment, for instance, tank containers and drums, our flexitanks for sale are usually cheaper. There’s a high chance you’ll spend 1/3 less than what you’d incur when using conventional bulk liquid containers.

Huge Shipping Capacity

Our flexibag can accommodate up to 24,000 liters in a common freight container. These containers can ship 50% more than bottled consignments and can accommodate 40% more than drummed consignments.


You’ll notice our flexibags for sale require less labor because they enable convenient handling, convenient loading, and unloading.


These bags are disposable, so you won’t incur cleaning costs.


You can easily ship flexitanks for sale around the globe within days and load them into 20 ft. containers. Also, they don’t need preparation before use.


Since you can recycle flexibags, they’re deemed environmentally safer.

Disadvantages of Flexbags

Container Damage

Flexibags for sale exert pressure on freight containers’ sidewalls, making them bulge beyond the ordinary size. This can disfigure the container permanently. For this reason, some carriers will avoid flexitank shipment.

Possible Leakage

flexitank container clean up

Although the storage bags comprise numerous layers, they’re still vulnerable to leakages. This can be because of excessive force causing rupture or crack, resulting in leakage.

Unavailability of essential equipment

You should know that it’s possible to lack appropriate unloading and loading equipment in some facilities. This restricts where you can transport your freight, leading to extra transport costs for liquid transportation to the intended destination.

Advantages of ISO Tanks

Economic benefits

iso-tank vs flexitank
iso-tank vs flexitank

A 20-ft or 24,000-liter container can hold about 45% more liquid than a normal 20-ft container. This implies that the freight remains constant but shipment is more, thus helping to decrease land and sea transportation.


Liquid transportation provides excellent security by preventing any kind of contamination or leakage.

Easy and Quick

The use of these tanks is very convenient and easy. You’ll discover that the time consumption of unloading and loading is less, making the operation simple.

Drawbacks of ISO Tanks

Site constraints

Containers are a big consumer of space.


They require cleaning after shipping. Although you can reuse them, they need cleaning at an approved facility. This could increase the cost of ownership or hire. Furthermore, it ties up containers in the supply chain. This means a waiting period might be necessary when the demand is high.

Costly Manufacture

Although they’re comparatively environmentally friendly during distribution, ISO tanks need considerable energy during production. This negates some of the associated benefits. They’re also expensive to replace and produce.

Various users face a difficult time when deciding whether to use ISO tanks or flexibags when it comes to transporting bulk liquids. The choice between these two relies on various factors and while both perform the same functions, this guide offers apparent differences worth noting.

Author: miamiseo