Chemicals are either transported in bulk (i.e. loose) or in different types of various sized packages (containers, drums, flasks, bags…).
Different types of specialised vessels are used to transport bulk substances:
- Bulk carriers are used to transport solid goods such as ores, metals, minerals or cereals. Due to the type of cargo, their structure can suffer major physical constraints during loading operations but also at sea.
- Chemical tankers are specially equipped to transport liquids such as petrochemical derivatives (benzene, PVC, ethylene…), vegetable and animal oils, concentrated acids or caustic soda. Their tanks are generally made of stainless steel and covering with a coating compatible with the substance transported (epoxy, zinc silicate...).
- Gas carriers are used to transport different types of gases such as natural gas, butane, propane, ethylene, ammonia… Their cargo is always transported in liquefied form, which requires high pressure (up to 600 times atmospheric pressure at ambient temperatures) or refrigeration (down to -162°C) at atmospheric pressure.
Multipurpose cargo vessels are non-specialised ships that can transport various types of packaged or bulk goods. Since the 1970s, they have been gradually giving way to more specialised vessels.
Container ships are vessels designed exclusively to transport containerised goods. The largest models currently in circulation can hold up to 11,000 TEU (twenty-foot equivalent units). Their colossal capacity constitutes both their strength and their weakness. The cargo sometimes piled high can generate stability problems for the vessel. Moreover, on longer ships, the structural constraints are considerable.
Last update: 12/10/2010