Chemical Tankers / Day 4 / Day 4 Topic 8 Tank Coating & Resistance List
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Stowage planning, tank cleaning
Avoid the stowage of "sensitive" cargoes such as refined foodstuffs, potable ethanol, methanol, ethylene glycol, iso-propanol, etc. in tanks where" incompatible“ cargoes have been stowed as first, second and, if applicable, third/fourth last.
The coating system should not only be resistant to the separate cargoes but also to the alternating action of different cargoes and cargo cleaning procedures.
Stowage planning, tank cleaning
While two successive cargoes may be individually compatible with a tank coating system, a mixture of the two, due to residues of the first cargo, may cause damage.
For example a cargo containing water follows a Vinyl Acetate Monomer cargo, residues of Vinyl Acetate Monomer in the tank lining (coating) will hydrolyse. By this process Acetic Acid is formed which will cause corrosion and attack the coating.
Ethylene Dichloride (EDC) and water will form Hydrochloric Acid, and
Chloroform and water form Formic Acid.
Stowage planning, tank cleaning
Special attention must be paid to additional notes, containing warnings/restrictions, for instance those concerning acidity/alkalinity , presence of water in the tanks, cleaning chemicals ,cargo residues, etc.
End of Topic