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Useful information on the practical terms used in the tank industry:

Dangerous goods are substances and articles which have been identified as hazardous for transport and present a risk to people, property and the environment.
Terms used in this guidance have the same meaning as in the ADR and current national legislation concerning the carriage of dangerous goods by road.

Useful Terms in tank container industry:




European Agreement Concerning the International Carriage of Dangerous Goods by Road (detailed provisions re-issued every two years by the United Nations Economic Commission for Europe)


Acceptable Container Condition


British Standard Pipe Thread - A pipe thread common on tank container fittings.

Ball Valve

A valve which is closed by rotating a ball with a central hole through 90 degrees. Provides unrestricted flow.


A metric unit of pressure. 1 Bar equals 14.504 pounds per square inch (psi)

Beam Tank

Tank container design where the barrel is the major load carrying component between the end frames.

Bursting (or Rupture or Frangible) Disc

A pressure relief device which breaks at a pre-set pressure. Used as an emergency relief or used as a hermetic seal for relief valves to prevent the release of toxic or especially hazardous vapors.

Butterfly Valve

A valve containing a circular plate that rotates through 90 degrees to close the opening.


A quick-disconnect type coupling sometimes used on bottom outlet valves.


Cubic Feet per Minute. Imperial measurement usually applied to airflow.

Closed Cup (CC)

Describes a method used to determine the flash point of a liquid.

Design Pressure

The pressure used to calculate the thickness of the barrel (shell) of the tank. Design pressure must be equal to or exceed the maximum allowable working pressure or be equal to or exceed the test pressure, depending on that code which is applicable.

Dangerous Goods Safety Adviser (road)

Dipstick or Dip Rod

Calibrated stainless steel bar placed inside the manway to measure cargo fill level.


Equipment Interchange Report

Filling Ratio

Maximum allowable weight of cargo per unit volume.

Flame Trap

A metal gauze that permits pressure to release but prevents flashback.

Foot Valve

Internal bottom outlet valve also known as emergency valve.

Frame Tank

Tank container design where a structural frame with continuous side rails is the major load support of the barrel.

Fusible Link

A heat-sensitive pressure relief device designed to relieve pressure when a specific temperature is reached, such as during a fire.

The Health and Safety Authority


Glass reinforced plastic resin used to encase insulation on a tank container.

ICAO technical instructions
The technical instructions published by the International Civil Aviation Organisation
The International Maritime Dangerous Goods Code


International Standards Organization - A specialized agency of the United Nations promoting the safe maritime transport of dangerous goods.

A multiple-element gas container

Material Safety Data Sheet (MSDS)

The product manufacturer's data sheet containing precise chemical name, composition, hazard information, transport and regulatory information and other pertinent data.


Maximum Allowable Working Pressure.

A mobile explosives manufacturing unit


Maximum Gross Weight: Tare + Maximum Payload


National Pipe Thread. The threading form for pipe fittings used in the USA.

The National Roads Authority
Any person or enterprise involved in the carriage of dangerous goods by road including any person involved in the activity of loading, unloading, packing and filling, and includes consignor, carrier, consignee, driver, vehicle crew, DGSA or any person with a duty under the regulations


Amount of cargo that can be transported.

Periodic Testing

Tank containers must undergo periodic inspections to uphold the validity of approvals.
5 Year Test - Includes a hydrostatic pressure test, a visual inspection (internal and external), a leakage test and a test of the satisfactory operation of all service equipment (including all valves and fittings).
2.5 Year Test - Includes a visual inspection (external and internal), a leakage test and a test of the satisfactory operation of all service equipment (including all valves and fittings).

Large hazard labels used on vehicles/tanks


Pounds per square inch - unit of pressure (1 psi = 0.069 bar)


Polytetrafluorethylene - A plastic used for seals and gaskets that has a wide temperature tolerance and resistant to most chemicals.

The regulations concerning the international carriage of dangerous goods by rail
The Road Safety Authority

Safety Relief Valve (SRV) or PV Valve

(Pressure, vacuum or combination relief valve) Designed to protect the tank against excessive overpressure or vacuum. As pressure relief, the valve is activated by inlet pressure and characterized by rapid opening or pop action. As vacuum relief, the valve is activated by inlet vacuum. The device is designed to re-close and prevent the further flow of fluid after excess pressure or vacuum has been relieved.

Specific Gravity (SG)

Ratio of density of substance to water. (Weight of water = 8.345 lbs/gal or 1 kg/litre.)

Steam Trap

Valve that only permits water to pass thereby trapping the steam until it condenses.

Syphon (or Dip) Tube

A tube inserted from the top outlet to the bottom of tank that allows liquid to be discharged through the top outlet by the use of pressure or suction.

A shell including its service and structural equipment. When used alone the term means tank-container, portable tank, demountable tank, fixed tank and tanks forming elements of a battery-vehicle or MEGC


Weight of container or vehicle without contents.


A term commonly used to denote the approved Customs sealing on a container.

Transport equipment
Includes vehicles, tanks, tank-containers, portable tanks, demountable tanks, tank swap bodies, tube trailers, bulk containers, intermediate bulk containers, containers, packaging, packages, receptacles and aerosols, and any other item used or intended for use in the carriage of dangerous goods by road

Ullage (or Outage)

That portion of the total capacity of a tank container not occupied by its liquid cargo expressed as a percentage of that capacity. The fill ranges between a minimum of 80% and a maximum of 97% for hazardous commodities.

UN Number

Refers to the United Nations (UN) four-digit identification number assigned to a hazardous material that is recognized for use in international and domestic commerce and transportation.

Vapor Pressure

The pressure that develops within a closed tank containing a liquid. Each liquid has its own vapor pressure that varies with temperature.


As in "pressure vessel" - the liquid-carrying portion or tank portion of an intermodal tank container.