Some of the most common hazards of bulk cargoes on board ships are as follow –
1) Cargo shift: Cargo shift has always remained as one of the greatest dangers on bulk carriers. This problem is greater for ships carrying grain cargoes. Grain settles by about 2% of its volume. Because of this settling, small void spaces exist on the top of grain surface. Trimming is undertaken to reduce the danger of cargo shifting.
2) Cargo falling from height: Cargoes like iron ore, quartz and steel scraps are high density cargo. There is a possibility of cargo falling from height during cargo operations. Cargo may either fall from the conveyor belt of the shiploader or from the discharging grab on to the deck of the ship. People working on deck can get injured badly if hit by the sizeable lumps of the bulk cargo.
3) Cargo falling from height: Dust is one of the most common hazards in bulk carriers. Many bulk cargoes are dusty by nature. Dust particles are small enough to be inhaled and if inhaled can have disastrous effects on health. Anyone working on the deck can be exposed to high levels of dust. Dust can cause sneezing and irritation of the eyes. Where possible it is always best to avoid exposure to cargo dust however if exposure cannot be avoided protective face masks should be worn.
4) Cargo Liquefaction: Liquefaction is a phenomenon in which solid bulk cargoes are abruptly transformed from a solid dry state to an almost fluid state.
Many common bulk cargoes such as iron ore fines, nickel ore and various mineral concentrates are examples of materials that may liquefy.
Liquefaction occurs as a result of compaction of the cargo which results from engine vibrations, ship‘s motion and rolling and wave impact that further causes cargo agitation. Liquefaction results in a flow state to develop.
5) Structural damage: Heavy cargoes place high loads on the structure and structural failure is therefore probable. High density cargoes occupy a small area for a large weight that is they have a low stowage factor. It is therefore important that the tank top has sufficient strength to carry heavy cargoes like iron ore, nickel ore, bauxite etc.
6) Oxygen depletion: Sea transportation of bulk cargoes of an organic nature such as wood, paper pulp and agricultural products may result in rapid and severe oxygen depletion and formation of carbon dioxide. Thus apparently harmless cargoes may create potentially life threatening conditions.
7) Corrosion: Some cargoes like coal and sulphur can cause severe damage due to corrosion. Cargoes of sulphur in bulk are normally subjected to exposed storage and are thus subjected to inclement weather thereby resulting in the increase of moisture content of the cargo. Wet sulphur is potentially highly corrosive. When sulphur is loaded, any retained free water filters to the bottom of the holds during the voyage, from where it is pumped out via the bilges.
8) Contamination: Preparation of cargo holds for the next intended carriage is a critical element of bulk carrier operations. A lack of proper preparation can lead to claims related to cargo quality such as contamination, water ingress or cargo loss. The bilges should be pumped out regularly during the voyage.
9) Fire: Bulk cargoes are deemed to present a great deal of fire hazards. Many bulk cargoes have a tendency to heat due to the oxidation process taking place during the voyage.