15.2.1 The ammonium nitrate
solution shall contain at least 7% by weight of water. The acidity
(pH) of the cargo when diluted with ten parts of water to one part
of cargo by weight shall be between 5.0 and 7.0. The solution shall
not contain more than 10 ppm chloride ions, 10 ppm ferric ions and
shall be free of other contaminants.
15.2.2 Tanks and equipment
for ammonium nitrate solution shall be independent of tanks and equipment
containing other cargoes or combustible products. Equipment which
may, in service or when defective, release combustible products into
the cargo (e.g. lubricants), shall not be used. Tanks shall not be
used for seawater ballast.
15.2.3 Except where expressly
approved by the Administration, ammonium nitrate solutions shall not
be transported in tanks which have previously contained other cargoes
unless tanks and associated equipment have been cleaned to the satisfaction
of the Administration.
15.2.4 The temperature of
the heat-exchanging medium in the tank heating system shall not exceed
160°C. The heating system shall be provided with a control system
to keep the cargo at a bulk mean temperature of 140°C. High-temperature
alarms at 145°C and 150°C and a low-temperature alarm at 125°C
shall be provided. Where the temperature of the heat-exchanging medium
exceeds 160°C, an alarm shall also be given. Temperature alarms
and controls shall be located on the navigating bridge.
15.2.5 If the bulk mean cargo
temperature reaches 145°C, a cargo sample shall be diluted with
ten parts of distilled or demineralized water to one part of cargo
by weight and the pH shall be determined by means of a narrow-range
indicator paper or stick. Acidity measurements shall then be taken
every 24 hours. If the pH is found to be below 4.2, ammonia gas shall
be injected into the cargo until the pH of 5.0 is reached.
15.2.6 A fixed installation
shall be provided to inject ammonia gas into the cargo. Controls for
this system shall be located on the navigation bridge. For this purpose,
300 kg of ammonia per 1,000 tonnes of ammonium nitrate solution shall
be available on board.
15.2.7 Cargo pumps shall
be of the centrifugal deepwell type or of the centrifugal type with
water-flushed seals.
15.2.8 Vent piping shall
be fitted with approved weatherhoods to prevent clogging. Such weatherhoods
shall be accessible for inspection and cleaning.
15.2.9 Hot work on tanks,
piping and equipment which have been in contact with ammonium nitrate
solution shall only be done after all traces of ammonium nitrate have
been removed, inside as well as outside.