Chemical Tankers / Day 1 / Day 1 Topic 5 Cargo Properties
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Inhibitor addition and precautions with self-reactive cargoes during voyage
The vapour from the cargo liquid will not necessary contain inhibitor as the two liquids will have different evaporation properties. This means that some solid polymer build-up can occur in the tank ventilators and screens, which must be cleared before suction pumping implodes the tank.
Inhibitor addition and precautions with self-reactive cargoes during voyage
The temperature of inhibited cargoes must be checked and recorded to note any abnormal rise that indicates either inhibitor failure and/or polymerization. Notice of any excessive temperatures should be sent to the Ship Manager/Operator ashore with request on action to be taken.
Classification of Oils
A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The term "drying" is actually a misnomer - the oil does not harden through the evaporation of water or other solvents, but through a chemical reaction in which the components crosslink by the action of oxygen.
Classification of Oils
A semi-drying oil is an oil which partially hardens when it is exposed to air. This is as opposed to a to drying oil, which hardens completely, or a non-drying oil, which does not harden at all. Oils with an iodine number of 115-130 are considered semi-drying
Classification of Oils
A non-drying oil is an oil which does not harden when it is exposed to air. This is as opposed to a to drying oil, which hardens completely, or a semi-drying oil, which partially hardens. Oils with an iodine number of less than 115 are considered non-drying.
List of Oils
Precautions during loading, discharging, sweeping, tank cleaning of various oils.
A Previous cargo, FOSFA Regulations
FOSFA (The Federation of Oils, Seeds and Fats Associations).
Internationally 85% of the global trade in oils and fats is traded under FOSFA contracts.
For FOSFA list of acceptable previous cargoes refer “slide notes”
Precautions during loading, discharging, sweeping, tank cleaning of various oils.
Previous cargoes carried in a ship’s tank/s can be a possible source of contamination. In spite of apparently adequate cleaning, residues from such cargoes can remain entrapped in the tank coatings or in areas of difficult accessibility. The FOSFA Operational Procedures put restrictions on what may have been carried as the immediate previous cargo, or the last two cargoes and, in the case of leaded products, the last three previous cargoes.
Precautions during loading, discharging, sweeping, tank cleaning of various oils.
The Federation’s standard terms incorporate reference to a list of banned substances that may not be carried as the immediate last cargo prior to loading of oils and fats, and the terms that apply in the absence of any express agreement to the contrary. An alternative clause, issued in the form of a sticker, calls for the immediate last cargo to be restricted to substances appearing on a positive list, comprising foodstuffs, processing aids and other similar materials known to be compatible with oils and fats.
For FOSFA list of banned immediate previous cargoes refer “slide notes”
Precautions during loading, discharging, sweeping, tank cleaning of various oils.
Some cargoes that you carry will be oil or fats, manufactured from vegetable or animal sources. These are called Animal Oils or Vegetable Oils.
These Oils are generally safe, but they are still COMBUSTIBLE liquids and they can have a tendency to OXIDISE.
Care should be taken for loading/discharging & transportation of these liquids as for the combustible liquids.