Chemical Tanker - Main Characteristics of Chemical Tankers

Main Characteristics of Chemical Tankers

Chemical tankers often have a system for tank heating in order to maintain the viscosity of certain cargoes, typically by passing pressurized steam through stainless steel 'heating coils' in the cargo tanks, transferring heat into the cargo which circulates in the tank by convection. Many modern chemical tankers feature double hull construction and have one tank for each pump with separate piping, which means that each tank can load a separate cargo without any mixing. Tank cleaning after discharging cargo is a very important aspect of chemical tanker operations, because tanks which are not properly cleaned of all cargo residue can adversely affect the purity of the next cargo loaded. Before tanks are cleaned, they must be properly ventilated and checked to be free of potentially explosive gases. Chemical tankers usually have transverse stiffeners on deck rather than inside the cargo tanks, in order to make the tank walls smooth and easier to clean by fitted tank cleaning machines.

Cargo tanks, either empty or filled, are normally protected against explosion by inert gas blankets. Often nitrogen is the inert gas used, supplied either from portable gas bottles or an inert gas generator (IGS) system.

Most new chemical tankers are built by shipbuilders in Japan, Korea or China, with other builders in Turkey, Italy, Germany and Poland. Japanese shipbuilders now account for the large majority of stainless steel chemical tankers built, as welding stainless steel to the accuracy required for cargo tank construction is a skill which is difficult to acquire.

The chemical tanker market is dominated by several major chemical tanker operators, including Stolt-Nielsen, Odfjell, Eitzen Chemical, Nordic Tankers, Tokyo Marine and Berlian Laju Tanker. Charterers, the end users of the ships, include oil majors and specialist chemical companies.