In this article we hope to answer your questions about what are tank containers and what types are available.
Tank containers are basically, cylindrical vessels held within a standard 20ft ISO frame and are used to deliver hazardous and non-hazardous products. There are various types of tank container and depending on what they are used for dictates the type of unit required. The storage vessels within tank containers are typically produced from stainless steel that is surrounded by a layer of insulation and an outer protective layer of polyurethane or aluminium. However, some pressure vessels may be constructed from other materials.
Like standard ISO shipping containers, tank containers are multimodal containers used for transportation of bulk liquids, gases and powders and conform to the same ISO standard and have the same frame dimensions and lifting points as ISO shipping containers.
Swap body tank containers are built to non-ISO dimensions and usually have a larger cubic capacity making them ideal for moving very light cargoes cost-effectively. This type of tank container is primarily used within Europe.
Tanks range in cubic capacity from 10,000 – 26,000-litres and have a maximum gross weight of around 30-tonnes. This wide range of capacities allows a tank to be constructed that maximises the volume of cargo that can be transported whilst taking into account all load restrictions that are in force for the cargo being transported.
Other fitments such as valves loading fittings and heating systems differ according to the requirements of the end user.
Tank containers have to be designed and built to ensure conformance with International regulations and are built specifically to suit the products being shipped.
Each and every hazardous chemical has a unique UN number assigned to it and those that are suitable for shipping within a tank container are designated with an additional ‘T’ code in the table and this indicates the type of tank that must be used for transporting it.
In general, tank containers must be at least 80% full, to prevent dangerous surging of liquids during transit. On the other hand, they shouldn’t be filled over 95% otherwise there will be insufficient ullage space to allow for thermal expansion of the contents.
Containers used for transporting foodstuffs must be labelled ‘Portable Liquids Only’ and some hazardous products have to be transported in a tank container that doesn’t have any in or outlet valve below the surface of the liquid. In general, tank containers are designed for an operating pressure of up to 3-bar and are tested up to 4.5-bar.
Typically, tank containers are used for shipping:
- Wines & Spirits
- Fruit juices
- Sweet Oils
- Toxic substances
Types of tank container:
Baffle Tanks – This type of container is designed for products with a high specific gravity that are transported with the fill below 80%. 80% is classified as the ‘minimal filling level’ but, in this container, the baffles provide stability of the contents during transit. This unit can be fitted with heating systems including steam, warm water and thermostatically controlled electrical heating systems as well as cooling systems as required.
Lined Tanks – are designed for transport of both high purity and highly corrosive products. This type of tank is lined and have additional safety systems including product level detection devices and overfill protection systems and some containers are fitted with GPS tracking systems. Typical linings include PTFE, rubber and phenolic resin together with a range of valve configurations to suit specific loading and discharging requirements.
Heated Tanks – Some products have to be kept warm during transit and these containers come with steam, water and electrical heating systems. Given that some products are extremely sensitive to even the smallest of temperature fluctuations, some of the heating systems installed in this type of container have to be extremely accurate.
Refrigerated or cool tank containers – these units are approved by international statutory authorities for the safe transportation of pharmaceutical products, fruit juice, milk and general purposes liquids. Cooling is provided by circulating either brine or a synthetic oil around external coils.
Gas Tanks – these zinc lined containers are for the transportation of non-refrigerant gases and the stainless steel variant is used for shipping of pharmaceutical grade propellants.
There are two types of frame on a tank container. There is the full frame shown here and the beam frame that can be seen in the main image.
You may be interested in tank container sales and hire.