Removal of Residue from Cargo Tanks by Ventilation

Abstract

For the chemical tanker, cargo residues of substances with a vapour pressure greater than 5×10³ Pa at 20°C may be removed from a cargo tank by ventilation. But according to the prevention of marine pollution (MARPOL73/78), the ones with a vapour pressure less than 5×10³ Pa at 20°C must not be removed by ventilation.
Recently stripping systems are developed, and on some chemical tankers the stripping residues quantity is decreased less than one litre by using thin pipe.
If chemical substances with the little vapour pressure are removed by ventilation, this procedure is very useful for the operation and the prevetion for sea pollution.
Hence the posibility of the removal by ventilation was examined by the model tank test and on board test. The experimental results show that the residues in the tank well is removed by ventilation using the suction pipe or stripping pipe. And the liquid adhering to the wall can be also removed by the ventilation.