Goal
To ensure that all ship staff involved in cargo operations have sufficient
information about cargo properties and operating the cargo system so they can
conduct cargo operations safely.
18.1 General
18.1.1 Those involved in liquefied gas carrier
operations shall be made aware of the special requirements associated with, and
precautions necessary for, their safe operation.
18.1.2 A copy of the Code, or national regulations
incorporating the provisions of the Code, shall be on board every ship covered by
the Code.
18.2 Cargo operations manuals
18.2.1 The ship shall be provided with copies of
suitably detailed cargo system operation manuals approved by the Administration such
that trained personnel can safely operate the ship with due regard to the hazards
and properties of the cargoes that are permitted to be carried.
18.2.2 The content of the manuals shall include, but
not be limited to:
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.1 overall operation of the ship from dry-dock
to dry-dock, including procedures for cargo tank cooldown and warm-up,
transfer (including ship-to-ship transfer), cargo sampling, gas-freeing,
ballasting, tank cleaning and changing cargoes;
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.2 cargo temperature and pressure control
systems;
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.3 cargo system limitations, including minimum
temperatures (cargo system and inner hull), maximum pressures, transfer
rates, filling limits and sloshing limitations;
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.4 nitrogen and inert gas systems;
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.5 firefighting procedures: operation and
maintenance of firefighting systems and use of extinguishing agents;
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.6 special equipment needed for the safe
handling of the particular cargo;
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.7 fixed and portable gas detection;
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.8 control, alarm and safety systems;
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.9 emergency shutdown systems;
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.10 procedures to change cargo tank pressure
relief valve set pressures in accordance with 8.2.8 and 4.13.2.3; and
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.11 emergency procedures, including cargo tank
relief valve isolation, single tank gas-freeing and entry and emergency
ship-to-ship transfer operations.
18.3 Cargo information
18.3.1 Information shall be on board and available to
all concerned in the form of a cargo information data sheet(s) giving the necessary
data for the safe carriage of cargo. Such information shall include, for each
product carried:
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.1 a full description of the physical and
chemical properties necessary for the safe carriage and containment of the
cargo;
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.2 reactivity with other cargoes that are
capable of being carried on board in accordance with the International
Certificate of Fitness for the Carriage of Liquefied Gases in Bulk;
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.3 the actions to be taken in the event of
cargo spills or leaks;
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.4 countermeasures against accidental personal
contact;
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.5 firefighting procedures and firefighting
media;
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.6 special equipment needed for the safe
handling of the particular cargo; and
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.7 emergency procedures.
18.3.2 The physical data supplied to the master, in
accordance with 18.3.1.1, shall include information regarding the relative cargo
density at various temperatures to enable the calculation of cargo tank filling
limits in accordance with the requirements of chapter 15.
18.3.3 Contingency plans in accordance with 18.3.1.3,
for spillage of cargo carried at ambient temperature, shall take account of
potential local temperature reduction such as when the escaped cargo has reduced to
atmospheric pressure and the potential effect of this cooling on hull steel.
18.4 Suitability for carriage
18.4.1 The master shall ascertain that the quantity and
characteristics of each product to be loaded are within the limits indicated in the
International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk
required by 1.4, and in the Loading and Stability Information booklet required by
2.2.5, and that products are listed in the International Certificate of Fitness for
the Carriage of Liquefied Gases in Bulk as required under section 4 of the
certificate.
18.4.2 Care shall be taken to avoid dangerous chemical
reactions if cargoes are mixed. This is of particular significance in respect
of:
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.1 tank cleaning procedures required between
successive cargoes in the same tank; and
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.2 simultaneous carriage of cargoes that react
when mixed. This shall be permitted only if the complete cargo systems
including, but not limited to, cargo pipework, tanks, vent systems and
refrigeration systems are separated as defined in 1.2.47.
18.4.3 Where products are required to be inhibited, the
certificate required by 17.8 shall be supplied before departure, otherwise the cargo
shall not be transported.
18.5 Carriage of cargo at low temperature
When carrying cargoes at low temperatures:
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.1 the cooldown procedure laid down for that
particular tank, piping and ancillary equipment shall be followed
closely;
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.2 loading shall be carried out in such a
manner as to ensure that design temperature gradients are not exceeded in
any cargo tank, piping or other ancillary equipment; and
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.3 if provided, the heating arrangements
associated with the cargo containment systems shall be operated in such a
manner as to ensure that the temperature of the hull structure does not fall
below that for which the material is designed.
18.6 Cargo transfer operations
18.6.1 A pre-cargo operations meeting shall take place
between ship personnel and the persons responsible at the transfer facility.
Information exchanged shall include the details of the intended cargo transfer
operations and emergency procedures. A recognized industry checklist shall be
completed for the intended cargo transfer and effective communications shall be
maintained throughout the operation.
18.6.2 Essential cargo handling controls and alarms
shall be checked and tested prior to cargo transfer operations.
18.7 Personnel training
18.7.1 Personnel shall be adequately trained in the
operational and safety aspects of liquefied gas carriers as required by the International Convention on Standards of Training, Certification and
Watchkeeping for Seafarers, 1978, as amended, the International
Safety Management Code and the Medical First Aid Guide (MFAG). As a
minimum:
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.1 all personnel shall be adequately trained in
the use of protective equipment provided on board and have basic training in
the procedures, appropriate to their duties, necessary under emergency
conditions; and
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.2 officers shall be trained in emergency
procedures to deal with conditions of leakage, spillage or fire involving
the cargo and a sufficient number of them shall be instructed and trained in
essential first aid for the cargoes carried.
18.8
Entry into enclosed spaces
footnote
18.8.1 Under normal operational circumstances,
personnel shall not enter cargo tanks, hold spaces, void spaces or other enclosed
spaces where gas may accumulate, unless the gas content of the atmosphere in such
space is determined by means of fixed or portable equipment to ensure oxygen
sufficiency and the absence of toxic atmosphere.
18.8.2 If it is necessary to gas-free and aerate a hold
space surrounding a type A cargo tank for routine inspection, and flammable cargo is
carried in the cargo tank, the inspection shall be conducted when the tank contains
only the minimum amount of cargo "heel" to keep the cargo tank cold. The hold shall
be re-inerted as soon as the inspection is completed.
18.8.3 Personnel entering any space designated as a
hazardous area on a ship carrying flammable products shall not introduce any
potential source of ignition into the space, unless it has been certified gas-free
and is maintained in that condition.
18.9 Cargo sampling
18.9.1 Any cargo sampling shall be conducted under the
supervision of an officer who shall ensure that protective clothing appropriate to
the hazards of the cargo is used by everyone involved in the operation.
18.9.2 When taking liquid cargo samples, the officer
shall ensure that the sampling equipment is suitable for the temperatures and
pressures involved, including cargo pump discharge pressure, if relevant.
18.9.3 The officer shall ensure that any cargo sample
equipment used is connected properly to avoid any cargo leakage.
18.9.4 If the cargo to be sampled is a toxic product,
the officer shall ensure that a "closed loop" sampling system as defined in 1.2.15
is used to minimize any cargo release to atmosphere.
18.9.5 After sampling operations are completed, the
officer shall ensure that any sample valves used are closed properly and the
connections used are correctly blanked.
18.10
Cargo emergency shutdown (ESD) system
18.10.1
General
18.10.1.1 A cargo emergency shutdown system shall be
fitted to stop cargo flow in the event of an emergency, either internally within the
ship, or during cargo transfer to ship or shore. The design of the ESD system shall
avoid the potential generation of surge pressures within cargo transfer pipe work
(see 18.10.2.1.4).
18.10.1.2 Auxiliary systems for conditioning the cargo
that use toxic or flammable liquids or vapours shall be treated as cargo systems for
the purposes of ESD. Indirect refrigeration systems using an inert medium, such as
nitrogen, need not be included in the ESD function.
18.10.1.3 The ESD system shall be activated by the
manual and automatic initiations listed in table 18.1. Any additional initiations
shall only be included in the ESD system if it can be shown that their inclusion
does not reduce the integrity and reliability of the system overall.
18.10.1.4 Ship's ESD systems shall incorporate a
ship-shore link in accordance with recognized standardsfootnote.
18.10.1.5 A functional flow chart of the ESD system and
related systems shall be provided in the cargo control station and on the navigation
bridge.
18.10.2
ESD valve requirements
18.10.2.1 General
18.10.2.1.1 The term ESD valve means any valve operated
by the ESD system.
18.10.2.1.2 ESD valves shall be remotely operated, be
of the fail-closed type (closed on loss of actuating power), be capable of local
manual closure and have positive indication of the actual valve position. As an
alternative to the local manual closing of the ESD valve, a manually operated
shut-off valve in series with the ESD valve shall be permitted. The manual valve
shall be located adjacent to the ESD valve. Provisions shall be made to handle
trapped liquid should the ESD valve close while the manual valve is also closed.
18.10.2.1.3 ESD valves in liquid piping systems shall
close fully and smoothly within 30 s of actuation. Information about the closure
time of the valves and their operating characteristics shall be available on board,
and the closing time shall be verifiable and repeatable.
18.10.2.1.4 The closing time of the valve referred to
in 13.3.1 to 13.3.3 (i.e. time from shutdown signal initiation to complete valve
closure) shall not be greater than:
where:
U
|
= |
ullage volume at operating signal level (m3); |
LR
|
= |
maximum loading rate agreed between ship and shore facility
(m3/h). |
The loading rate shall be adjusted to limit surge pressure on valve
closure to an acceptable level, taking into account the loading hose or arm, the
ship and the shore piping systems, where relevant.
18.10.2.2 Ship-shore and ship-ship manifold
connections
One ESD valve shall be provided at each manifold connection. Cargo
manifold connections not being used for transfer operations shall be blanked with
blank flanges rated for the design pressure of the pipeline system.
18.10.2.3 Cargo system valves
If cargo system valves as defined in section 5.5 are also ESD valves
within the meaning of 18.10, then the requirements of 18.10 shall apply.
18.10.3
ESD system controls
18.10.3.1 As a minimum, the ESD system shall be capable
of manual operation by a single control on the bridge and either in the control
position required by 13.1.2 or the cargo control room, if installed, and no less
than two locations in the cargo area.
18.10.3.2 The ESD system shall be automatically
activated on detection of a fire on the weather decks of the cargo area and/or cargo
machinery spaces. As a minimum, the method of detection used on the weather decks
shall cover the liquid and vapour domes of the cargo tanks, the cargo manifolds and
areas where liquid piping is dismantled regularly. Detection may be by means of
fusible elements designed to melt at temperatures between 98°C and 104°C, or by area
fire detection methods.
18.10.3.3 Cargo machinery that is running shall be
stopped by activation of the ESD system in accordance with the cause and effect
matrix in table 18.1
18.10.3.4 The ESD control system shall be configured so
as to enable the high-level testing required in 13.3.5 to be carried out in a safe
and controlled manner. For the purpose of the testing, cargo pumps may be operated
while the overflow control system is overridden. Procedures for level alarm testing
and re-setting of the ESD system after completion of the high-level alarm testing
shall be included in the operation manual required by 18.2.1.
Table 18.1 - ESD functional
arrangements
Note 1: These items of equipment can be omitted from these specific
automatic shutdown initiators, provided the equipment inlets are protected against
cargo liquid ingress.
Note 2: If the fuel gas compressor is used to return cargo vapour to
shore, it shall be included in the ESD system when operating in this mode.
Note 3: If the reliquefaction plant compressors are used for vapour
return/shore line clearing, they shall be included in the ESD system when operating
in that mode.
Note 4: The override system permitted by 13.3.7 may be used at sea to
prevent false alarms or shutdowns. When level alarms are overridden, operation of
cargo pumps and the opening of manifold ESD valves shall be inhibited except when
high-level alarm testing is carried out in accordance with 13.3.5 (see
18.10.3.4).
Note 5: Cargo spray or stripping pumps used to supply forcing vaporizer
may be excluded from the ESD system only when operating in that mode.
Note 6: The sensors referred to in 13.3.2 may be used to close
automatically the tank filling valve for the individual tank where the sensors are
installed, as an alternative to closing the ESD valve referred to in 18.10.2.2. If
this option is adopted, activation of the full ESD system shall be initiated when
the high-level sensors in all the tanks to be loaded have been activated.
Note 7: These items of equipment shall be designed not to restart upon
recovery of main electric power and without confirmation of safe conditions.
* Fusible plugs, electronic point temperature monitoring or
area fire detection may be used for this purpose on deck.
** Failure of hydraulic, electric or pneumatic power for
remotely operated ESD valve actuators.
*** Indirect refrigeration systems which form part of the
reliquefaction plant do not need to be included in the ESD function if they employ
an inert medium such as nitrogen in the refrigeration cycle.
**** Signal need not indicate the event initiating ESD.
Functional requirement.
N/A Not applicable.
18.10.4
Additional shutdowns
18.10.4.1 The requirements of 8.3.1.1 to protect the
cargo tank from external differential pressure may be fulfilled by using an
independent low pressure trip to activate the ESD system, or, as minimum, to stop
any cargo pumps or compressors.
18.10.4.2 An input to the ESD system from the overflow
control system required by 13.3 may be provided to stop any cargo pumps or
compressors' running at the time a high level is detected, as this alarm may be due
to inadvertent internal transfer of cargo from tank to tank.
18.10.5
Pre-operations testing
Cargo emergency shutdown and alarm systems involved in cargo transfer
shall be checked and tested before cargo handling operations begin.
18.11 Hot work on or near cargo containment
systems
18.11.1 Special fire precautions shall be taken in the
vicinity of cargo tanks and, particularly, insulation systems that may be flammable
or contaminated with hydrocarbons or that may give off toxic fumes as a product of
combustion.
18.12 Additional operating requirements
Additional operating requirements will be found in the following
paragraphs of the Code: 2.2.2, 2.2.5, 2.2.8, 3.8.4, 3.8.5, 5.3.2, 5.3.3.3, 5.7.3,
7.1, 8.2.7, 8.2.8, 8.2.9, 9.2, 9.3, 9.4.4, 12.1.1, 13.1.3, 13.3.6, 13.6.18, 14.3.3,
15.3, 15.6, 16.6.3, 17.4.2, 17.6, 17.7, 17.9, 17.10, 17.11, 17.12, 17.13, 17.14,
17.16, 17.18, 17.19, 17.21, 17.22.