Tank Container Glossary

AAR – American Association of Railroads




Approval Agency/Inspection Authority – Organization approved by a competent authority to inspect and certify equipment.


ASME – American Society of Mechanical Engineers. Publisher of internationally recognized codes for pressure vessels.


ATP – Agreement on the International Carriage of Perishable Foodstuffs and on the special equipment to be used for such carriage.

Ball Valve – A valve which is closed by rotating a ball with a central hole through 90 degrees.


BAM – Bundesanstatl Fur Materialforschung und Prufung.


Bar – Unit of pressure. (International Bar = 100 Kilopascal = 14.5 psi).


BS – British Standards. UK standards organization.


BS Table D – Specification for bolted flanges for pressure applications.


BSP – British Standards Pipe Thread. A thread form common on pipe fittings.


BSW – British Standard Whitworth. A screw thread commonly used on clamp bolts. Sometimes interchangeable with ISO metric coarse threads.


Bursting Disc – A pressure-relief device which breaks at a pre-determined pressure. Used for emergency relief or 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 which rotates through 90 degrees to close the opening. Easy to clean but restricts the fluid flow slightly.

Camlock – A quick-release type coupling sometimes used on bottom-outlet systems.


CCC – Customs Convention on Containers. Allows temporary admission of tanks into member countries.


CFM – Cubic Feet per Minute. Imperial measurement of rate flow. Usually applied to airflow


CFR – Code of Federal Regulations


Closed Cup (CC) – Describes a method used to ascertain the flash point of a liquid.


Competent authority – Regulating authority for national government.


CSC – International Convention for Safe Containers.

Design pressure – The pressure used to calculate the thickness of the shell of the tank. Design codes require the design pressure to equal or exceed the maximum allowable working pressure or equal or exceed the test pressure depending on which code is applicable.


Dipstick (dip rod) – Calibrated stainless steel bar situated in the manhole at the volumetric center to measure the level to which the tank has been filled.


DNV – Det Norske Veritas (a Norwegian approval society)


DOT US – Department of Transport. Competent authority for the United States of America.

EIR/RE – Equipment Interchange Report/Repair Estimate


Filling ratio – Maximum permissible mass of cargo as a percentage of the capacity.


Flame Trap – A metal gauze which permits gases to pass through but does not permit flame to pass (flashback)


Foot valve – Internal bottom-outlet valve situated in the knuckle of the dished end. Also know as emergency valve. Specified for hazardous products.

GRP (FRP) – Glass-reinforced plastic (fibre-reinforced polyester) resin sheet with a glass-fibre used to encase insulation.

No Terms


IMO – International Maritime Organization.


In Hg – Inches of Mercury. Unit of measurement for low pressures (usually vacuum).


ISO – International Standards Organization. An advisory body, whose recommendations have been accepted and incorporated into the official technical standards of many countries in the area of the transportable container, the aim of the organization is to achieve a standard approach to cargo container design and handling.


ISO 9002 – An internationally recognized quality system intended to satisfy a user’s needs or requirements.

No Terms


Kg/cm2 – Kilograms per square centimeter. (Unit of pressure)


K Pa (KN/M2) – Kilopascal (Unit of pressure)

No Terms


MARPOL – International convention for the prevention of pollution from ships.


MAWP – Maximum allowable working pressure


MGW – Maximum Gross Weight = TARE + MAXIMUM PAYLOAD


MSDS – Material Safety Data Sheet. This identifies the physical properties and hazards of product.

NPT – National Pipe Thread. The thread form for pipe fittings used in the USA.


No Terms


Passivation – A process which encourages the corrosion resistance of stainless steel by the forming of chrome oxide layer on the steel surface.


Payload – Mass of cargo that can be carried


PCD – Pitch Circle Diameter. Diameter of circle upon which bolt holes are positioned.


Periodic Tests – These are performed every 2.5 years. The depot ensures the tank is repaired and ready for the test and then certified test authorities (BV, DNV, LR etc) perform the tests. In the 2.5 year test, the tank is filled with air under pressure and checked to see it is completely airtight. The 5 year periodic test known as a Hydrostatic Test, must be performed every 5 years and in this test the tank is filled with water and checked for leaks. Hazardous cargoes may only be transported in tank containers which have a valid test certificate.


Pickling – A chemical or electrochemical method of removing mill scale, rust, metal oxides and similar coatings from steel.


Plug valve – A valve consisting of a plug which is moved in and out of its seating by an operated mechanism.


PSI (Ib/in2) – Pound per square inch (unit of pressure)


PTFE – Polytetrafluorethylene. A plastic used for seals and bearings. Has a wide temperature tolerance and is resistant to most chemicals.


P/V Valve – A combined pressure and vacuum-relief valve to protect the tank against excessive overpressure and vacuum.


PR Valve – A pressure relief valve to protect the tank against accidental overpressure. As the P/V valve (above) but without the vacuum relief facility.

No Terms

Reference Temperature – A temperature allocated to particular zones throughout the world.


SG Specific Gravity – The relative weight or density of a solid or fluid expressed by the ratio of its weight to that of an equal volume of a substance taken as a standard, water in the case of liquids and solids, air for gases. The higher the SG, the smaller the tank will be.


SNCF – Societe Nationale de Chemin de Fer Francais. French Railways competent authority.


Steam trap – Valve which permits only water to pass


SWG – Standard Wire Gauge. Standards for metal sheet and wire thickness.


Syphon tube (dip tube) – A tube from the top outlet to the bottom of the tank which allows liquid to be discharged or loaded through the top outlet/inlet by means of pressure (or suction)

Tare – Mass of an empty tank in operational condition.


Thermostat – A temperature sensor operating an electrical switch. Used to maintain a temperature within set limits.


TIR – International agreement to standardize the Customs sealing of road vehicles crossing international boundaries. This agreement does not apply to containers which must be approved under the Customs Convention on Containers. The term TIR however is still commonly used to denote the approved sealing on a container. (See International Transport of Goods Under Customs Seal. Conditions of Approval Publication VE 505 Published by DOT UK).


Total containment pressure – The sum of the internal pressures to which a tank container is subjected in normal service. This total pressure must not exceed the maximum allowable working pressure of the tank.

UIC – Union International des Chemin de Fer. Publisher of regulations for tank container marking and registration for international rail transport.


Ullage (Outage) – Free space within vessel after loading.


UN Number – A numbering system recommended by the United Nations Committee of Experts on the Transport of Dangerous Goods for the aim of worldwide harmonization in this field.

Vapor pressure – The developed pressure within a closed vessel containing a liquid. Each liquid has its own vapor pressure which varies with temperature


Viton A – A synthetic rubber used for seals. Has good sealing properties and is tolerant of a wide range of chemical.

Walkway – This runs the length of the tank allowing safe access to all of the components on the top of the tank. It is generally made from non-skid marine aluminum.

No Terms

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