7.1.1 When provided,
any cargo heating or cooling systems shall be constructed, fitted
and tested to the satisfaction of the Administration. Materials used
in the construction of temperature-control systems shall be suitable
for use with the product intended to be carried.
LR 7.1
General
LR 7.1(a) For the carriage of cargoes for which special
temperature control is required, as noted in column 'o' in the table of Chapter 17, heating and/or cooling systems complying with
the requirements set out hereunder, are to be provided. Where appropriate, notations in
the Register Book will be assigned as provided for in LR III.2 Class Notation (refrigerated installation).
LR 7.1(b) When temperature control systems installed for operational
reasons, such as those intended for maintaining cargoes other than those listed above,
at temperatures suitable for the preservation of quality, or at viscosities which
facilitate cargo transfer, comply fully with the requirements, they will also be
eligible for the class notations given in LR III.2 Class Notation (refrigerated installation).
LR 7.2
Systems
LR 7.2(a) Temperature control systems include the
following:
| Active
|
Pipe coils or ducts for circulating a
heating or cooling medium within, or adjacent to, the bulk of the
cargo.
|
| or
|
A heat exchanger through which the
cargo and a heating or cooling medium is circulated.
|
| Passive
|
Thermal insulation of tanks intended
to maintain a pre-heated or pre-cooled cargo within a specified range of
temperatures for a limited period of time without applied heating or
cooling.
|
LR 7.3
Requirements
LR 7.3(a) Capacity
LR 7.3(a).1
Active heating and cooling systems are to have capacity such that the cargo in the
designated tanks can be maintained at the carrying temperature under the following
conditions:
|
|
Heating systems
|
Cooling systems
|
| Seawater temperature
|
0°C
|
32°C
|
| Air temperature
|
5°C
|
45°C
|
| Limiting
tank boundary temperatures to be specified.
|
NOTE: For the purpose of calculation it is to be assumed that the cargo is
loaded at the carrying temperature.
LR 7.3(a).2
If capacity in excess of that required to comply with the foregoing is installed for
the purpose of heating or cooling cargoes to temperatures different from that at which
they are loaded, the distinguishing mark ‡ will be assigned.
LR 7.3(a).3
Passive systems will be examined in respect of suitability for specified cargoes,
conditions and voyages, on submission of relevant details.
LR 7.3(a).4
Where cooling systems incorporate mechanical refrigeration, the installation is to
comply with the requirements of Pt 6, Ch 3 Refrigerated Cargo Installations of the Rules for Ships, so far as they are applicable. Such
an installation is not to be used for any other cooling duty.
LR 7.3(b)
Stand-by plant
LR 7.3(b).1
Heating and cooling systems are to be duplicated to the following extent:
LR 7.3(b).2
Coil or duct systems are to have not less than two independent circuits per tank.
There is to be sufficient capacity for the total required minimum heating or cooling
with any one circuit out of action, and the circuits are to be so arranged that the
heating or cooling can be evenly distributed throughout the cargo.
LR 7.3(b).3
Deck lines for heating and cooling media need not be duplicated.
LR 7.3(b).4
There are to be two independent sources of heat input. These may be boilers or other
devices such as calorifiers or air heaters, each being of sufficient capacity to supply
at least the minimum requirement.
LR 7.3(b).5
Heat exchangers (where fitted) are to be duplicated.
LR 7.3(b).6
Circulating pumps for both cargo, and heating or cooling media (where fitted) are to
be duplicated. Cargo pumps may be used for cargo circulation if suitable.
LR 7.3(b).7
Refrigeration plant for cargo cooling is to comply with Pt 6, Ch 3, 2.2 Refrigerants and classes of pipes 2.2.1 of the Rules for Ships, with regard to
stand-by capacity.
LR 7.3(b).8 All duplicate machinery and circuits are to be capable of
being isolated without inhibiting the operation of the remainder of the system.
7.1.2 Heating
or cooling media shall be of a type approved for use with the specific
cargo. Consideration shall be given to the surface temperature of
heating coils or ducts to avoid dangerous reactions from localized
overheating or overcooling of cargo. (See also Ch 1, 15.13 Cargoes protected by additives 15.13.6.)
7.1.4 In any heating
or cooling system, means shall be provided to ensure that, when in
any condition other than empty, a higher pressure can be maintained
within the system than the maximum pressure head that could be exerted
by the cargo tank contents on the system.
7.1.5 Means shall
be provided for measuring the cargo temperature.
-
The means for measuring the cargo temperature shall be of restricted
or closed type, respectively, when a restricted or closed gauging device is
required for individual substances, as shown in column j in the table of
chapter 17.
-
A restricted temperature-measuring
device is subject to the definition for a restricted gauging device
in Ch 1, 13.1 Gauging 13.1.1.(b) (e.g. a portable
thermometer lowered inside a gauge tube of the restricted type).
-
A closed temperature-measuring
device is subject to the definition for a closed gauging device in Ch 1, 13.1 Gauging 13.1.1.(c) (e.g. a remote-reading
thermometer of which the sensor is installed in the tank).
-
When overheating or
overcooling could result in a dangerous condition, an alarm system
which monitors the cargo temperature shall be provided. (See also
operational requirements in Ch 1, 16.6 Cargoes not to be exposed to excessive heat.)
LR 7.4
Cargo temperature measurement
(Applicable to tanks which are designated for the carriage of
temperature-controlled cargoes).
LR 7.4(a)
In each integral tank, temperature measuring positions are to be so disposed that a
reliable mean cargo temperature can be obtained. Where limiting tank boundary
temperatures are specified, means for determining these temperatures are also to be
provided.
LR 7.4(b)
For the carriage of ammonium nitrate solutions (UN 2426) and hydrogen peroxide (UN
2015) there are to be not less than five measuring points per tank, in well separated
positions spanning substantially the full depth and horizontal area of the tank, one of
which is to be in the vicinity of the volumetric centroid of the tank.
LR 7.4(c)
Similar provision is recommended for all high viscosity and polymerising
cargoes.
LR 7.4(d)
Where cargoes are carried in integral tanks at temperatures which could influence
the properties of the structural steelwork, additional measuring points and alarms may
be required.
LR 7.4(e)
Independent tanks intended for the carriage of heated or cooled cargoes are to have
not less than two measuring points, well separated within the centre 60 per cent of the
tank depth.
LR 7.4(f)
In tanks of all types, intended for the carriage of heated or cooled cargoes there
are to be alternative means of measuring temperatures:
LR 7.4(g)
For ‘closed’ temperature measuring devices, all sensors may be connected to a single
indicator/ recorder, but a stand-by indicator/recorder with suitable switching
arrangements is to be provided. Alternatively, there may be at least two
indicator/recorders, each permanently connected to approximately half the sensors in
each tank.
LR 7.4(h)
Tanks which are adapted primarily to ‘restricted’ temperature measuring devices are
to have at least one ‘closed’ device per tank which can be read under all sea
conditions.
7.1.6 When products for which Ch 1, 15.12 Toxic products
Ch 1, 15.12 Toxic products 15.12.1 or Ch 1, 15.12 Toxic products 15.12.3 are listed in column o in the table of
chapter 17 are being heated or cooled, the heating or
cooling medium shall operate in a circuit:
-
which is independent
of other ship's services, except for another cargo heating or cooling
system, and which does not enter the machinery space; or
-
which is external to
the tank carrying toxic products; or
-
where the medium is
sampled to check for the presence of cargo before it is recirculated
to other services of the ship or into the machinery space. The sampling
equipment shall be located within the cargo area and be capable of
detecting the presence of any toxic cargo being heated or cooled.
Where this method is used, the coil return shall be tested not only
at the commencement of heating or cooling of a toxic product, but
also on the first occasion the coil is used subsequent to having carried
an unheated or uncooled toxic cargo.