13.7.1
Integrity of barriers
Where a secondary barrier is required, permanently installed
instrumentation shall be provided to detect when the primary barrier
fails to be liquid-tight at any location or when liquid cargo is in
contact with the secondary barrier at any location. This instrumentation
shall consist of appropriate gas detecting devices according to 13.6.
However, the instrumentation need not be capable of locating the area
where liquid cargo leaks through the primary barrier or where liquid
cargo is in contact with the secondary barrier.
13.7.2
Temperature indication devices
13.7.2.1 The number and position of temperature-indicating
devices shall be appropriate to the design of the containment system
and cargo operation requirements.
13.7.2.2 When cargo is carried in a cargo containment
system with a secondary barrier, at a temperature lower than -55°C,
temperature-indicating devices shall be provided within the insulation
or on the hull structure adjacent to cargo containment systems. The
devices shall give readings at regular intervals and, where applicable,
alarm of temperatures approaching the lowest for which the hull steel
is suitable.
13.7.2.3 If cargo is to be carried at temperatures
lower than -55°C, the cargo tank boundaries, if appropriate for
the design of the cargo containment system, shall be fitted with a
sufficient number of temperature-indicating devices to verify that
unsatisfactory temperature gradients do not occur.
13.7.2.4 For the purposes of design verification
and determining the effectiveness of the initial cooldown procedure
on a single or series of similar ships, one tank shall be fitted with
devices in excess of those required in 13.7.2.1. These devices may
be temporary or permanent and only need to be fitted to the first
ship, when a series of similar ships is built.