5.1.1 Tanks that have been cleaned and gas-freed
should be re-inerted preferably during the ballast voyage to allow
the inert gas system to be fully tested prior to cargo handling. Purge
pipes/vents should be opened to atmosphere. When the oxygen concentration
of the atmosphere in the tank has fallen below 8% the purge pipes/vents
should be closed and the tank pressurized with inert gas.
5.1.2 During the re-inerting of a tank following
a breakdown and repair of the inert gas system, non-gas-free and non-inerted
tanks should be re-inerted in accordance with 5.1.1.
During inerting, no ullaging, dipping, sampling or other equipment
should be inserted unless it has been established that the tank is
inert. This should be done by monitoring the efflux gas from the tank
being inerted until the oxygen content is less than 8% by volume and
for such a period of time as determined by previous test records when
inerting gas-free tanks to ensure that the efflux gas is fully representative
of the atmosphere within the tank.
5.1.3 When all tanks have been inerted, they should
be kept common with the inert gas main and maintained at a positive
pressure in excess of 100 mm water gauge during the rest of the cycle
of operation.