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Cargo holds are the revenue earning space of a bulk carrier. Depending on the size, a bulk carrier can have from one to ten cargo holds. The three major commodities in worldwide bulk trade are: iron ore, coal and grain.
Cargo holds are subject to severe abrasion and mechanical damage from hard and abrasive bulk cargoes:
- scrap iron and iron ore pellets are typical examples which have high abrasive impact on bulkheads and hatch covers
- coal may be a very corrosive cargo if sulphuric acid is developed during transportation
- the temperature of a coal cargo may be very high - either because temperature is high during loading or because coal generates heat due to oxidation
Consequently, abrasion resistance, chemical resistance, corrosion resistance and heat resistance are important properties which have to be built into the coating system for cargo holds. Further requirements include:
- certificates for the transportation of grain as it is important that the coating system does not exude substances harmful to the health
- the coating must be easy to clean, and cleaning is most effectively controlled if the cargo hold is coated in a light colour
- the coating system must also have optimum adhesion and flexibility in order to provide the corrosion protection required i.e. against the extensive deformation of the steel when loading, discharging and mooring
The cost of maintenance and the risk of loss of business due to contamination of succeeding cargoes from damaged cargo hold coatings can have serious economic consequences for a bulk carrier. It is therefore of outmost importance to select a coating that gives optimal protection and long maintenance intervals for a vessels cargo holds.
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