Ballast tank corrosion protection - using protective atmos., with controlled oxygen content

摘要

Corrosion protection esp. of a ship's ballast tank is effected by maintaining a protective gas atmos. in the ballast water-free space of the tank, the atmos. consisting of 1.8-10 vol.% O2, max. 0.2 vol.% CO2 and balance N2 and/or noble gas(es) and its O2 content being monitored and held within the prescribed range. The protective gas contains 2.8-3.2 vol.%, is free of CO2 and contains Ar as the noble gas. The protective atmos. can be produced on board ship by air fractionation or esp. by combustion of e.g. oil and CO2 removal from the combustion gas. USE/ADVANTAGE - For large ships e.g. oil tankers and ore freighters and provides effective prevention or redn. of corrosion of the steel ballast tanks by eliminating the deleterious effects of oxygen and sulphur bacteria.