Safe Handling of Tank Containers - ITCO

ICHCA International Safety Panel Briefing Pamphlet No 30
3.3 Compartments and Baffles
3.3.1 The IMDG Code prescribe minimum filling rules for tank containers.
Generally, these require tanks filled with free-flowing liquids, including
liquefied gases, to be filled to not less than 80% of their volume. Further
information on the rules governing the minimum and maximum degrees of
filling of tank containers laden with dangerous goods and goods not
regulated as dangerous for transport are given in Annex 2 section A2.2.
3.3.2 Baffles
3.3.2.1 The majority of tank containers are built with a single chamber free from any
sharp corner / edges. The smoothness of this simple internal design
provides the operator with an easy to clean surface.
3.3.2.2 Baffles (more properly known as surge plates within the IMDG Code) are
required to ensure the longitudinal stability of the tank container is
maintained when it is loaded to less than 80% of the pressure vessel’s
volume.
3.3.2.3 Baffles are fitted within the single chamber pressure vessel to reduce the
free flow of liquids as the container is moved during transport. Picture 11
shows the upper of two transverse surge plates fitted to the interior of a
pressure vessel. However Picture 12 shows an example of a full diameter
surge plate as is more commonly fitted than the design shown in Picture 11
3.3.3 Compartments
A limited number of tank containers are built with two or more discrete
compartments. The single shell is constructed in the same manner as a
normal tank container, except that one or more watertight bulkheads are
welded across the shell’s cross section. Outwardly there will be loading and
discharge valves and a manway for each compartment. Each of these
compartments is capable of carrying a different cargo or in some cases it is
possible to carry a single cargo in one compartment and leave the other
compartments empty. See also section 10.2.6.
3.3.4 Marking
Picture 11 Picture 12
3.3.4.1 At the time of writing this pamphlet there was no regulation or requirement to
mark tank containers to indicate if they are fitted with baffles or built with
compartments. However the IMDG Code requires that the water capacity at
20ºC shall be marked on a corrosion resistant metal identification plate fitted
to every portable tank. The plates should also show the water capacity of
each compartment at 20ºC. An entry shown in this section of the plate
indicates that the tank container is divided into compartments but does not
indicate the number of compartments unless there is more than one value
shown.
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