Goal
To ensure that the instrumentation and automation systems provides for the safe
carriage, handling and conditioning of cargo liquid and vapour.
13.1
General
LR 13.1-01 The requirements of this Chapter are additional to
those of Pt 6, Ch 1 of the Rules for Ships, Control Engineering Systems.
13.1.1 Each cargo tank shall be provided with a means
for indicating level, pressure and temperature of the cargo. Pressure gauges and
temperature indicating devices shall be installed in the liquid and vapour piping
systems, in cargo refrigeration installations.
13.1.2 If loading and unloading of the ship is
performed by means of remotely controlled valves and pumps, all controls and
indicators associated with a given cargo tank shall be concentrated in one control
position.
13.1.3 Instruments shall be tested to ensure
reliability under the working conditions, and recalibrated at regular intervals.
Test procedures for instruments and the intervals between recalibration shall be in
accordance with manufacturer's recommendations.
13.2 Level indicators for cargo tanks
13.2.1 Each cargo tank shall be fitted with liquid
level gauging device(s), arranged to ensure that a level reading is always
obtainable whenever the cargo tank is operational. The device(s) shall be designed
to operate throughout the design pressure range of the cargo tank and at
temperatures within the cargo operating temperature range.
13.2.2 Where only one liquid level gauge is fitted, it
shall be arranged so that it can be maintained in an operational condition without
the need to empty or gas-free the tank.
13.2.3 Cargo tank liquid level gauges may be of the
following types, subject to special requirements for particular cargoes shown in
column "g" in the table of chapter 19:
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.1 indirect devices, which determine the amount
of cargo by means such as weighing or in-line flow metering;
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.2 closed devices which do not penetrate the
cargo tank, such as devices using radio-isotopes or ultrasonic devices;
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.3 closed devices which penetrate the cargo
tank, but which form part of a closed system and keep the cargo from being
released, such as float type systems, electronic probes, magnetic probes and
bubble tube indicators. If closed gauging device is not mounted directly
onto the tank, it shall be provided with a shutoff valve located as close as
possible to the tank; and
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.4 restricted devices which penetrate the tank
and, when in use, permit a small quantity of cargo vapour or liquid to
escape to the atmosphere, such as fixed tube and slip tube gauges. When not
in use, the devices shall be kept completely closed. The design and
installation shall ensure that no dangerous escape of cargo can take place
when opening the device. Such gauging devices shall be so designed that the
maximum opening does not exceed 1.5 mm diameter or equivalent area, unless
the device is provided with an excess flow valve.
LR 13.2–01 Where level gauges containing cargo are mounted
externally on tanks, they are to be arranged to be isolated in the event of
failure.
13.3
Overflow control
13.3.1 Except as provided in 13.3.4, each cargo tank
shall be fitted with a high liquid level alarm operating independently of other
liquid level indicators and giving an audible and visual warning when activated.
13.3.2 An additional sensor operating independently of
the high liquid level alarm shall automatically actuate a shutoff valve in a manner
that will both avoid excessive liquid pressure in the loading line and prevent the
tank from becoming liquid full.
13.3.3 The emergency shutdown valve referred to in 5.5
and 18.10 may be used for this purpose. If another valve is used for this purpose,
the same information as referred to in 18.10.2.1.3 shall be available on board.
During loading, whenever the use of these valves may possibly create a potential
excess pressure surge in the loading system, alternative arrangements such as
limiting the loading rate shall be used.
LR 13.3–01 The sensor for automatic closing of the shut-off valve
for overflow control as required by 13.3.2 may also perform the function of liquid
level gauging as required by 13.2.1.
13.3.4 A high liquid level alarm and automatic shut-off
of cargo tank filling need not be required, when the cargo tank:
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.1 is a pressure tank with a volume not more
than 200 m3; or
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.2 is designed to withstand the maximum
possible pressure during the loading operation, and such pressure is below
that of the set pressure of the cargo tank relief valve.
13.3.5 The position of the sensors in the tank shall be
capable of being verified before commissioning. At the first occasion of full
loading after delivery and after each dry-docking, testing of high-level alarms
shall be conducted by raising the cargo liquid level in the cargo tank to the alarm
point.
13.3.6 All elements of the level alarms, including the
electrical circuit and the sensor(s), of the high, and overfill alarms, shall be
capable of being functionally tested. Systems shall be tested prior to cargo
operation in accordance with 18.6.2.
13.3.7 Where arrangements are provided for overriding
the overflow control system, they shall be such that inadvertent operation is
prevented. When this override is operated, continuous visual indication shall be
given at the relevant control station(s) and the navigation bridge.
13.4
Pressure monitoring
13.4.1 The vapour space of each cargo tank shall be
provided with a direct reading gauge. Additionally, an indirect indication shall be
provided at the control position required by 13.1.2. Maximum and minimum allowable
pressures shall be clearly indicated.
13.4.2 A high-pressure alarm and, if vacuum protection
is required, a low-pressure alarm shall be provided on the navigation bridge and at
the control position required by 13.1.2. Alarms shall be activated before the set
pressures are reached.
13.4.3 For cargo tanks fitted with PRVs which can be
set at more than one set pressure in accordance with 8.2.7, high-pressure alarms
shall be provided for each set pressure.
LR 13.4–01 These alarms are also to be provided at the cargo
control position.
LR 13.4-02 It is recommended that the high-pressure alarms
activate at 90 per cent of the cargo tank’s maximum allowable (design) pressure. It
is recommended that the low-pressure alarm activates at least 0,0005 MPa before the
minimum set pressure is reached.
13.4.4 Each cargo-pump discharge line and each liquid
and vapour cargo manifold shall be provided with at least one pressure
indicator.
13.4.5 Local-reading manifold pressure indication shall
be provided to indicate the pressure between ship's manifold valves and hose
connections to the shore.
13.4.6 Hold spaces and interbarrier spaces without open
connection to the atmosphere shall be provided with pressure indication.
13.4.7 All pressure indications provided shall be
capable of indicating throughout the operating pressure range.
13.5 Temperature indicating devices
13.5.1 Each cargo tank shall be provided with at least
two devices for indicating cargo temperatures, one placed at the bottom of the cargo
tank and the second near the top of the tank, below the highest allowable liquid
level. The lowest temperature for which the cargo tank has been designed, as shown
on the International Certificate of Fitness for the Carriage of Liquefied Gases in
Bulk required by 1.4.4, shall be clearly indicated by means of a sign on or near the
temperature indicating devices.
13.5.2 The temperature indicating devices shall be
capable of providing temperature indication across the expected cargo operating
temperature range of the cargo tanks.
13.5.3 Where thermowells are fitted, they shall be
designed to minimize failure due to fatigue in normal service.
13.6
Gas detection
13.6.1 Gas detection equipment shall be installed to
monitor the integrity of the cargo containment, cargo handling and ancillary
systems, in accordance with this section.
13.6.2 A permanently installed system of gas detection
and audible and visual alarms shall be fitted in:
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.1 all enclosed cargo and cargo machinery
spaces (including turrets compartments) containing gas piping, gas equipment
or gas consumers;
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.2 other enclosed or semi-enclosed spaces where
cargo vapours may accumulate, including interbarrier spaces and hold spaces
for independent tanks other than type C tanks;
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.3 airlocks;
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.4 spaces in gas-fired internal combustion
engines, referred to in 16.7.3.3;
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.5 ventilation hoods and gas ducts required by
chapter 16;
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.6 cooling/heating circuits, as required by
7.8.4;
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.7 inert gas generator supply headers; and
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.8 motor rooms for cargo handling
machinery.
LR 13.6–01 In addition, where cargo is used as a fuel outside of
the cargo area, permanently installed gas detection is also to be provided for:
- .1. other enclosed or semi-enclosed spaces outside of the cargo
area where cargo vapours may accumulate including gas valve unit rooms;
- .2. the spaces in gas fired internal combustion engines required
by LR 16.7-05 in Chapter 16 including crankcases, sumps, scavenge spaces and
cooling system vents.
13.6.3 Gas detection equipment shall be designed,
installed and tested in accordance with recognized standardsfootnote and shall be suitable for the cargoes to
be carried in accordance with column "f" in table of chapter 19.
13.6.4 Where indicated by an "A" in column "f"
in the table of chapter 19 ships certified for carriage of non-flammable products,
oxygen deficiency monitoring shall be fitted in cargo machinery spaces and hold
spaces for independent tanks other than type C tanks. Furthermore, oxygen deficiency
monitoring equipment shall be installed in enclosed or semi-enclosed spaces
containing equipment that may cause an oxygen-deficient environment such as nitrogen
generators, inert gas generators or nitrogen cycle refrigerant systems.
LR 13.6-02 Two oxygen sensors are to be positioned at appropriate locations in
the space or spaces containing the inert gas system, in accordance with paragraph
15.2.2.4.5.4 of the FSS Code, for all gas carriers, irrespective of the carriage of
cargo indicated by an ‘A’ in column ‘f’ of the table in Chapter 19 of the Code.
13.6.5 In the case of toxic products or both toxic and
flammable products, except when column "i" in the table of chapter 19 refers
to 17.5.3, portable equipment can be used for the detection of toxic products as an
alternative to a permanently installed system. This equipment shall be used prior to
personnel entering the spaces listed in 13.6.2 and at 30-minute intervals while they
remain in the space.
13.6.6 In the case of gases classified as toxic
products, hold spaces and interbarrier spaces shall be provided with a permanently
installed piping system for obtaining gas samples from the spaces. Gas from these
spaces shall be sampled and analysed from each sampling head location.
13.6.7 Permanently installed gas detection shall be of
the continuous detection type, capable of immediate response. Where not used to
activate safety shutdown functions required by 13.6.9 and chapter 16, sampling type
detection may be accepted.
13.6.8 When sampling type gas detection equipment is
used, the following requirements shall be met:
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.1 the gas detection equipment shall be capable
of sampling and analysing for each sampling head location sequentially at
intervals not exceeding 30 min;
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.2 individual sampling lines from sampling
heads to the detection equipment shall be fitted; and
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.3 pipe runs from sampling heads shall not be
led through non-hazardous spaces except as permitted by 13.6.9.
LR 13.6–03 In cargo hold spaces, the sampling heads are not to be
located where bilge water can collect.
13.6.9 The gas detection equipment may be located in a
non-hazardous space, provided that the detection equipment such as sample piping,
sample pumps, solenoids and analysing units are located in a fully enclosed steel
cabinet with the door sealed by a gasket. The atmosphere within the enclosure shall
be continuously monitored. At gas concentrations above 30% lower flammable limit
(LFL) inside the enclosure, the gas detection equipment shall be automatically shut
down.
13.6.10 Where the enclosure cannot be arranged directly
on the forward bulkhead, sample pipes shall be of steel or equivalent material and
be routed on their shortest way. Detachable connections, except for the connection
points for isolating valves required in 13.6.11 and analysing units, are not
permitted.
13.6.11 When gas sampling equipment is located in a
non-hazardous space, a flame arrester and a manual isolating valve shall be fitted
in each of the gas sampling lines. The isolating valve shall be fitted on the
non-hazardous side. Bulkhead penetrations of sample pipes between hazardous and
non-hazardous areas shall maintain the integrity of the division penetrated. The
exhaust gas shall be discharged to the open air in a safe location.
13.6.12 In every installation, the number and the
positions of detection heads shall be determined with due regard to the size and
layout of the compartment, the compositions and densities of the products intended
to be carried and the dilution from compartment purging or ventilation and stagnant
areas.
13.6.13 Any alarms status within a gas detection system
required by this section shall initiate an audible and visible alarm:
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.1 on the navigation bridge;
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.2 at the relevant control station(s) where
continuous monitoring of the gas levels is recorded; and
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.3 at the gas detector readout location.
13.6.14 In the case of flammable products, the gas
detection equipment provided for hold spaces and interbarrier spaces that are
required to be inerted shall be capable of measuring gas concentrations of 0% to
100% by volume.
13.6.15 Alarms shall be activated when the vapour
concentration by volume reaches the equivalent of 30% LFL in air.
LR 13.6–04 For the spaces described by LR 13.6-01, alarms shall be
activated when the vapour concentration reaches 30 per cent LFL and safety functions
required by 16.4.8 in Chapter 16 shall be activated before the vapour concentration
reaches 60 per cent LFL. The crankcases of diesel engines that can also run on gas
shall be arranged to alarm before 100 per cent LFL.
13.6.16 For membrane containment systems, the primary
and secondary insulation spaces shall be able to be inerted and their gas content
analysed individuallyfootnote. The alarm in the secondary insulation space shall be
set in accordance with 13.6.15, that in the primary space is set at a value approved
by the Administration or recognized organization acting on its behalf.
13.6.17 For other spaces described by 13.6.2, alarms
shall be activated when the vapour concentration reaches 30% LFL and safety
functions required by chapter 16 shall be activated before the vapour concentration
reaches 60% LFL. The crankcases of internal combustion engines that can run on gas
shall be arranged to alarm before 100% LFL.
13.6.18 Gas detection equipment shall be so designed
that it may readily be tested. Testing and calibration shall be carried out at
regular intervals. Suitable equipment for this purpose shall be carried on board and
be used in accordance with the manufacturer's recommendations. Permanent connections
for such test equipment shall be fitted.
13.6.19 Every ship shall be provided with at least two
sets of portable gas detection equipment that meet the requirement of 13.6.3 or an
acceptable national or international standard.
13.6.20 A suitable instrument for the measurement of
oxygen levels in inert atmospheres shall be provided.
13.7 Additional requirements for containment systems
requiring a secondary barrier
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.
LR 13.7–01 The regular temperature measurements required by
13.7.2.2 are to be automatically recorded and the alarm is to be provided at the
cargo control position and on the navigating bridge.
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.
13.8
Automation systems
LR 13.8–01 The particular requirements of this Section shall be in
accordance with Pt 6, Ch 1,2.10 to 2.13 of the Rules for Ships.
13.8.1 The requirements of this section shall apply
where automation systems are used to provide instrumented control, monitoring/alarm
or safety functions required by this Code.
13.8.2 Automation systems shall be designed, installed
and tested in accordance with recognized standardsfootnote.
13.8.3 Hardware shall be capable of being demonstrated
to be suitable for use in the marine environment by type approval or other
means.
13.8.4 Software shall be designed and documented for
ease of use, including testing, operation and maintenance.
13.8.5 The user interface shall be designed such that
the equipment under control can be operated in a safe and effective manner at all
times.
13.8.6 Automation systems shall be arranged such that a
hardware failure or an error by the operator does not lead to an unsafe condition.
Adequate safeguards against incorrect operation shall be provided.
13.8.7 Appropriate segregation shall be maintained
between control, monitoring/alarm and safety functions to limit the effect of single
failures. This shall be taken to include all parts of the automation systems that
are required to provide specified functions, including connected devices and power
supplies.
13.8.8 Automation systems shall be arranged such that
the software configuration and parameters are protected against unauthorized or
unintended change.
13.8.9 A management of change process shall be applied
to safeguard against unexpected consequences of modification. Records of
configuration changes and approvals shall be maintained on board.
13.8.10 Processes for the development and maintenance
of integrated systems shall be in accordance with recognized standardsfootnote. These processes shall include appropriate risk
identification and management.
LR 13.8–02 Where the requirement of 13.8.10 is to be met by the
application of ISO 17894:2005 Ships and marine technology – Computer applications
– General principles for the development and use of programmable electronic
systems in marine applications, it is to be applied at the ‘total system’
level and not the subsystem level for which ISO 17894:2005 is not appropriate. The
concept of ‘total system’ is detailed in the standard.
13.9 System integration
LR 13.9–01 The particular requirements of this Section shall be
in accordance with Pt 6, Ch 1,2.14 of the Rules for Ships.
13.9.1 Essential safety functions shall be designed
such that risks of harm to personnel or damage to the installation or the
environment are reduced to a level acceptable to the Administration, both in normal
operation and under fault conditions. Functions shall be designed to fail-safe.
Roles and responsibilities for integration of systems shall be clearly defined and
agreed by relevant parties.
13.9.2 Functional requirements of each component
subsystem shall be clearly defined to ensure that the integrated system meets the
functional and specified safety requirements and takes account of any limitations of
the equipment under control.
13.9.3 Key hazards of the integrated system shall be
identified using appropriate risk-based techniques.
13.9.4 The integrated system shall have a suitable
means of reversionary control.
13.9.5 Failure of one part of the integrated system
shall not affect the functionality of other parts, except for those functions
directly dependent on the defective part.
13.9.6 Operation with an integrated system shall be at
least as effective as it would be with individual stand-alone equipment or
systems.
13.9.7 The integrity of essential machinery or systems,
during normal operation and fault conditions, shall be demonstrated.