Chemical Tankers / Day 2 / Day 2 Topic 2 Cargo Compatibility
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Reactivity , Solubility, Compatibility
Consideration must be given to chemical storage:
Drums: heat / condition / accessibility markings
Tanks: cleanliness / marking / fittings
Reactivity , Solubility, Compatibility
Tank Coatings
Various information sources and warning systems are available to prevent coating damage due to reactivity:
Manufacturer’s Compatibility Guides
Reactivity , Solubility, Compatibility
Particular reactions with coatings:
Possibility of increased acidity with certain slops, eg: VAM
Damage to Epoxy coatings due to adding water after Alcohols, Esters, Ketones, etc
Alkaline washings (Caustic) in zinc coated tanks
Reactivity ,Solubility,Compatibility
Tank Coating Resistancy Guides
Reference tables and notes produced by the manufacturer of the coating material
Reactivity ,Solubility,Compatibility
Heat
Voyage Requirements: Cargo may be damaged if heated too fast, too high or too long (scorching and discoloration) - careful planning and monitoring are required.
Water
Particularly during cleaning:
Relatively small quantities highly reactive with Acids
Salt water aggressive to Stainless Steel
Reactivity ,Solubility,Compatibility
Salt Water reactive with Latex (coagulation)
Highly reactive with all Isocyanates - solidification and generation of large volumes of Carbon Dioxide gas (see cleaning procedures in Chemical Tanker Manual )
Also during Tank Preparation - several cargoes require super-dry tanks, eg: Propylene Oxide, Isocyanates
Reactivity ,Solubility,Compatibility
Air
Mostly it is the moisture in the air that is the problem and therefore the “water” section applies.
Some cargoes however react to other impurities in the air (eg Hexamethylene Diamine - HMD) or the oxygen itself (eg Propylene Oxide)
Problems are usually eliminated by the application and maintenance of a Nitrogen blanket
Reactivity ,Solubility,Compatibility
Solubility:
We have already defined this as “the tendency of a cargo to dissolve”.
This information is therefore of great use to us in Tank Cleaning - Most completely water-soluble cargoes are considered good last cargoes and little or no problem is anticipated in cleaning.