Leak

A cargo tank or package may leak its contents as exemplified by mv. ‘Anna Broere’ which on collision leaked 550 tonnes of Acrylonitrile into the sea. The types of cargo carried in chemical tankers are described in chapter 17 of the IBC Code, those exhibiting the most severe safety and environmental and hazards being transported in a type 1 chemical tanks While those progressively less hazardous are carried in tanks of types 2 and 3 . Most chemical tankers have double hulls to provide high collision protection.

Picture 33 The chemical tanker ‘‘Ievoli Sun’’ loaded with approximately 4000 tonnes Styrene, 1000 tonnes Methyl Ethyl Ketone (MEK) and 1000 tonnes Iso Propyl Alcohol (IPA) sank in the English Channel after tugboats unsuccessfully tried to tow her into safety. She sunk in 90 m of water depth offshore the Island of Alderney. (November 1999)Copyright photo SMIT

Picture 34 Ship leaking chemical substance Copyright photo RWS

The fate of a substance released to the sea is greatly dependent on its behaviour classification as presented in section 2.4.5.

Many substances cannot be recovered once spilled because they evaporate, dissolve or otherwise disperse. Nonetheless, measures should be taken to avoid contact with humans, particularly with toxic substances until they dilute to non-toxic concentrations. In assessing safety thresholds, the MAC value is often used for gases and 1% of the LC50 (96) value for dissolvers