One of the possible causes of explosions in tankers which have occurred in the past is thought to be the discharge of static electricity, generated by high-pressure seawater jets used in cleaning empty tanks, in the presence of oxygen in the air and residual oil vapour.
To eliminate this possibility the inert gas system was introduced, and it is now being installed in new tankers being built and older ones already in service. By substituting inert gas instead of normal air with its oxygen content tanks, the conditions for ignition are never present. The inert gas system involves the cleansing of boiler smoke, or diesel exhaust gas, by ‘scrubbing’ cooling, filtering (or dusting-off), chemically neutralising and demisting, before the cold inert gas is blown into the holds of the tanker.
The scrubber in the main part of the system where the smoke, or diesel exhaust gas, is firstly sprayed and saturated with seawater, almost completely cleansed of sulphur, and finally ‘dusted off’ by filtering down to less than a micron. In the process, the liquid mixture produced with the scrubber contains sulphurous/ sulphuric acids heavily contaminated with chlorides which can present a serious corrosion problem.
The scrubber illustrated is one of three built by Société Française d’Aerodynamique et de Thermodynamique SOFRAIR, 1 Avenue de Chatou- F 92508 Rueil-Malmaison, France, for their inert gas systems in three new tankers. It is approximately 43 ½” in diameter and 157” in height.
Because of the highly corrosive environment in which it operates each scrubber has been fabricated in FERRALIUM 255 alloy plate. FERRALIUM 255 alloy is super duplex stainless steel having an excellent corrosion resistance and high mechanical strength. For this latter reason, also, it is used for the inert gas fan impellers, where high peripheral speeds are normal.
If you’d like more information regarding Ferralium 255, please get in touch with a member our expert team today.