Transport Guidance for Steel Cargoes

American Club: Transport Guidance for Steel Cargoes
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6. Ventilation of steel cargoes
6.1 Objective:
To properly ventilate the cargo holds to reduce the likelihood of condensation damage
 
 
 
 
to steel cargoes.
6.2 Purpose of ventilation
6.2.1
The purpose of ventilating steel cargoes is to remove any relatively warm moist air surrounding the
cargo and replace it with cooler and drier air to minimize condensation onto the cold steelwork of
the hold and drip down onto the steel cargo. Ventilation should not be used as a means to cool the
cargo. The temperature of the bulk of the cargo will remain essentially constant throughout the voyage.
6.2.2
To prevent condensation, the cargo holds should be ventilated when the vessel transits from warmer
to cooler climates where a simultaneous reduction in sea water temperature may cause the
accumulation of moisture from the surrounding air onto the colder surfaces.
6.3 Condensation due to “sweat”
6.3.1
Definition of sweat. “Sweat” is the formation of condensation within a vessel’s hold. There are
two types of sweat.
(1)
Ship sweat. Moisture (condensation) that forms on the vessel’s structure is known
as “ship sweat”.
(2)
Cargo sweat. Moisture (condensation) that forms on the cargo itself is known
as “cargo sweat”.
6.3.2
Ship sweat. Ship sweat traditionally occurs when a vessel loads cargo in a warm, moist atmosphere,
and then sails into locations with much cooler climates. As the vessel’s steelwork cools, moisture
from the humid atmosphere in the holds will condense on the colder steel surface of the hold.
6.3.2.1 In general, ship sweat only forms in significant quantities when a vessel is carrying a

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