12.4.1 Small particulate matter carried in flue
gas can be electrostatically charged. The level of charge is usually
small, but levels have been observed well above those encountered
with water mists formed during tank washing.
12.4.2 Because cargo tanks are normally in an
inerted condition, the possibility of electrostatic ignition has to
be considered only if the oxygen content of the tank atmosphere rises
as a result of an ingress of air or if it is necessary to inert a
tank which already has a flammable atmosphere (see 5.1).