The Tank Container Components

ISO Tank Container

The ISO tank container (or intermodal tank) is a pressure vessel mounted in a frame that complies with the recommendations of the International Standards Organization (ISO). It is designed and constructed in accordance with strict international codes for the worldwide transportation of hazardous and non-hazardous bulk liquids via land, rail and water.

The vessel of the ISO tank is constructed of various grades of stainless steel. A Tank is classified according to the specifications of its shell and fittings and this classification determines what type of product can be carried.


The tank container consists of a single, cylindrical vessel within a rectangular steel frame which is designed according to strict specifications of the International Standards Organization (ISO). The typical tare weight of a tank container ranges between 3,400 kg and 4,500 kg.

Tank Cylinder
The tank cylinder (or shell, or barrel) is usually constructed from stainless steel, carbon steel or aluminum and has a load/discharge opening (manlid) on the top and normally one discharge facility opening at the bottom.

One or two safety relief valves are designed to control or limit the pressure in the tank shell which can build up by a process upset, instrument or equipment failure, or fire.

A triple bottom outlet closure consisting of a remote-controlled foot valve, butterfly or ball valve and a cap is installed to avoid leakage of product.

The tank body or shell is welded within a frame which is used to support and protect it from damage during handling, transportation or the eventuality of an accident or rollover. The frame is designed to specific dimensions and tolerances according to International Standards Organization (ISO) requirements and meets strict stacking, longitudinal and lateral inertia standards. The standard dimensions are 6,048 mm (20') x 2,438mm (8') x 2,591mm (8' 6"). The frame requires impact testing and meets the criteria of the Association of American Railroads (AAR) and Transport Canada (TC).

Various Standard Parts of the Tank Container

  • A ladder and a walkway are installed for easy access to the top connection fittings and manlid.
  • A stainless steel dipstick for measuring volume of product and a corresponding calibration chart can be provided.
  • A watertight document holder is attached along the side of the tank container.
  • A data plate is installed on all tank containers with specific identification information.

The 500mm (20-inch) stainless steel manlid with an incorporated gasket covers the centrally located loading manhole on the top of the tank container. Each manlid is secured with 8 swingbolt assemblies.

PTFE (Polytetrafluoroethylene) is the standard gasket material used because of its tolerance to a wide range of temperatures and is resistant to most chemicals. An alternative is SWR (Sweet White Rubber) used for food-grade quality cargoes. Other gasket materials are available upon customers' requests.

Top Outlet
The top outlet is located on the top, towards the rear of the tank and unless requested to be fitted, it is normally blanked off. When required, a 3-inch plate valve or butterfly valve, a 3-inch BS table ‘D' flange and a blanking plate will be provided.

Bottom Outlet
The bottom outlet consists of a triple-closure system consisting of (1) an internal foot valve operated by a remotely located external handle, (2) a 3-inch butterfly or ball valve with a (3) 3-inch bsp screwed outlet cap. Bottom outlets are prohibited when carrying certain types of hazardous materials. The remote closure arm is located on the side of the tank, allowing the discharge valve to be closed from a safe location in the event of spillage or fire.

Safety Relief Valve
One or two combined pressure vacuum relief valves are installed on each tank container to protect the vessel from excessive over-pressurization and or vacuum.

Airline Valve
The airline valve is used for pressurizing the tank during discharge or testing and for vapor recovery. It terminates in a 1-1/2"BSP male threaded connection and screw cap.

The insulation is a minimum 50mm thick and is covered with either a 2mm thick glass reinforced plastic (GRP) or 1.8mm aluminum. All joints are sealed to prevent moisture from building up underneath the cladding.

Heating - Steam
Steam heating is the most efficient means of heating the tank cargo and is standard on most of Multistar's tank containers. The typical heating area is 8 square meters. The steam channels, continuous loops of pipe work, usually on the outside of the lower third of the tank, terminate at the rear of the tank and are closed by threaded dust caps. The outlet should be fitted with a steam condensate trap. Care should be taken to ensure the maximum working pressure of the system (as indicated on the data plate) should not be exceeded.

Heating - Electric
This external shell heating system consists of a network of elements in contact with the shell over the bottom third of the tank container. Used for maintaining the temperature of heat sensitive products, this system operates on either 200-280V 3-phase or 340-480V 3-phase. Electric heating is designed to maintain the product at a specific temperature, not to reheat the product. This system is available on certain tank containers upon special request.