Section
10 Storage and use of chemicals
10.1 Reductants used for selective catalytic reduction (SCR)
10.1.3 Storage tanks are to be protected from excessively high or low
temperatures. Depending on the operational area of the ship, this may necessitate
the fitting of heating and/or cooling systems in accordance with Vol 2, Pt 12, Ch 1, 5.1 General 5.1.3. The physical
conditions recommended by the applicable recognised standards (such as ISO 18611-3)
are to be taken into account to avoid any impairment of urea solution during
storage.
10.1.4 The storage tanks may be located within the engine room.
10.1.5 Where storage tanks are integrated, the following are to be considered during the
design and construction:
- These tanks shall be designed and constructed as integral part of the hull
(e.g. double bottom, wing tanks);
- These tanks shall be coated with appropriate anti-corrosion coating or shall
be made of adequate corrosion resistant materials and cannot be located
adjacent to any fuel oil and fresh water tank;
- These tanks shall be designed and constructed in accordance
with the structural requirements applicable to hull and primary support
members described in Vol 2, Pt 12, Ch 1, 5 Hull construction; and
- These tanks shall be included in the ship’s stability calculation.
10.1.6 The storage tank piping is to meet the requirements of Vol 2, Pt 12, Ch 1, 7.1 General 7.1.1, and Ventilation
arrangements required to comply with the chemical, biological, radiological and
nuclear defence (CBRN) requirements given in Vol 1, Pt 4, Ch 1, 7 Design guidance for nuclear, biological and chemical defence, will be specially considered.
10.1.8 The storage tank piping and venting systems are to be independent of other ship
service piping and/or systems.
10.1.9 The storage tank piping systems are not to be located in accommodation, service
spaces or control stations.
10.1.10 Reductant tanks are to be of steel or other equivalent material with a
melting point above 925°C. Pipes/piping systems are to be of steel or other
equivalent material with melting point above 925°C, except downstream of the tank
valve, provided this valve is metal seated and, in the event of fire, is arranged as
fail-to-closed or equipped with quick closing facilities at a safe position outside
the space. In such cases, type approved plastic piping may be accepted even if it
has not passed a fire endurance test. Reductant tanks and pipes/piping systems are
to be made with a material compatible with reductant or coated with appropriate
anti-corrosion coating.
10.1.11 Where storage tanks are installed in closed compartments, the
compartments are to be served by an effective extraction type mechanical ventilation
system capable of providing not less than six air changes per hour, which is
independent from the ventilation system of accommodation, service spaces or control
stations.
10.1.12 The ventilation system is to be capable of being controlled from outside
the compartment and is to be in continuous operation except when the storage tank is
empty and has been thoroughly ventilated.A warning notice requiring the use of such
ventilation before entering the compartment shall be provided outside the
compartment adjacent to teach point of entry.
10.1.13 The requirements to the ventilation system specified in this paragraph
and above paragraph Vol 2, Pt 12, Ch 1, 10.1 Reductants used for selective catalytic reduction (SCR) 10.1.11 also apply to the
following closed compartments normally entered by persons:
- When such closed compartments are adjacent to the integral
urea tanks and there are possible leakage points (e.g. manholes, fittings) from
these tanks;
- When the chemical piping systems pass through such
compartments, unless the piping system is made of steel or other equivalent
material with a melting point above 925°C.
10.1.14 The vent pipes of the storage tank are to terminate in an area on the weather deck
with no ignition hazard. The tank venting system is to be arranged to prevent
entrance of water into the storage tank.
10.1.15 The storage tanks are to be arranged so that they can be emptied and
ventilated by means of portable or permanent systems. The drainage arrangements are
to be independent of drainage arrangements of other systems and shall be capable of
draining to a dedicated tank.
10.1.16 Where a storage tank is located within an engine room, a separate
ventilation system defined in Vol 2, Pt 12, Ch 1, 10.1 Reductants used for selective catalytic reduction (SCR) 10.1.8 is not required when the general
ventilation system for the space is arranged so as to provide an effective movement
of air in the vicinity of the storage tank, and is to be maintained in operation
continuously except when the storage tank is empty and has been thoroughly
ventilated.
10.1.17 In the event of a ventilation failure, an audible and visual alarm shall be provided
outside the compartment adjacent to each point of entry and inside the compartment,
together with a warning notice requiring the use of such ventilation.
10.1.19 For the protection of crew members, the ship is to have suitable personnel protective
equipment on board. Eyewash stations are to be provided in locations where chemical
contact is most likely to occur. The location (e.g. near storage tank, loading area
etc.) and number of these eyewash stations is to be derived from the detailed
installation arrangements.
10.1.21 Aqueous ammonia is not to be used as a reductant in a SCR except where it can be
demonstrated that it is not practicable to use urea solution as the reductant.
10.1.22 Where an application is made to use aqueous ammonia as the reductant, then the
arrangements for its loading, carriage and use are to be derived from a risk-based
analysis.
10.1.24 Anhydrous ammonia is not to be used as a reductant in a SCR except where it can be
demonstrated that it is not practicable to use urea solution as the reductant, and
where the Flag Administration agrees to its use.
10.1.25 Where it is not practicable to use urea solution as the reductant, then it is also to
be demonstrated that it is not practicable to use aqueous ammonia.
10.1.26 Where an application is made to use anhydrous ammonia as the reductant, then the
arrangements for its loading, carriage and use are to be derived from a risk-based
analysis.
10.2 Chemical treatment fluids used for exhaust
gas cleaning systems (EGCS)
10.2.1 The aqueous solution of sodium hydroxide (NaOH) or calcium hydroxide
(Ca(OH)2) is commonly used as a chemical treatment fluid used for
EGCS. Where other chemical treatment fluids are used, safety measures are to be
taken according to the result of a risk assessment conducted to analyse the risks,
in order to eliminate or mitigate the hazards to personnel on board the ship.
10.2.2 The storage tank for chemical treatment fluid is to be arranged so that any leakage
will be contained and prevented from making contact with heated surfaces. All pipes
and other tank penetrations are to be provided with manual closing valves attached
to the tank. In cases where such valves are provided below the top of tank, they are
to be provided with quick closing valves which are to be capable of being remotely
operated from a position safely accessible in the event of chemical treatment fluid
leakage. Tank and piping arrangements are to be approved.
10.2.3 The storage tank for chemical treatment fluid is to be protected from excessively
high or low temperatures applicable to the particular concentration of chemical
treatment fluids. Depending on the operational area of the ship, this may require
the fitting of heating and/or cooling systems.
10.2.4 If a storage tank for chemical treatment fluid is installed in a closed compartment,
then the area is to be served by an effective mechanical ventilation system of the
extraction type, providing not less than 6 air changes per hour, which is
independent from the ventilation system of accommodation, service spaces, or control
stations. The ventilation system is to be capable of being controlled from outside
the compartment. A warning notice requiring the use of such ventilation before
entering the compartment shall be provided outside the compartment adjacent to each
point of entry.
10.2.5 The requirements specified in Vol 2, Pt 12, Ch 1, 10.2 Chemical treatment fluids used for exhaust gas cleaning systems (EGCS) 10.2.4 also apply to closed
compartments normally entered by persons:
- when they are adjacent to the integral storage tank for chemical
treatment fluid and there are possible leak points (e.g. manhole, fittings)
from these tanks; or
- when the treatment fluid piping systems pass through these
compartments, unless the piping system is made of steel or other equivalent
material with melting point above 925°C and with fully welded joints.
10.2.6 The storage tank may be located within the engine room. In this case, a separate
ventilation system is not required when a general ventilation system for the space
providing not less than 6 air changes per hour is arranged so as to provide an
effective movement of air in the vicinity of the storage tank and is maintained in
operation continuously except when the storage tank is empty and has been thoroughly
ventilated.
10.2.7 Each storage tank for chemical treatment fluid is to be provided with level
monitoring arrangements and high/low level alarms. In cases where heating and/or
cooling systems are provided, high and/or low temperature alarms or temperature
monitoring are also to be provided.
10.2.8 The storage tanks are to have sufficient strength to withstand a pressure
corresponding to the maximum height of a fluid column in the overflow pipe, with a
minimum of 2,4 m above the top plate, taking into consideration the density of the
treatment fluid.
10.2.9 Where chemical treatment fluid is stored in integral tanks, the following are to be
considered during their design and construction:
- these tanks shall be designed and constructed as an integral part of the
hull (e.g. double bottom, wing tanks); and
- these tanks shall be coated with appropriate anti-corrosion coating and are
to be segregated by cofferdams or other similar spaces from accommodation,
cargo spaces containing cargoes which react with chemical treatment fluid in
a hazardous manner, food stores, oil tanks, lube oil tanks, aviation fuel
tanks or fresh water tanks.
10.2.10 The chemical treatment fluid piping and venting systems are to be independent of
other ship piping systems. The chemical treatment fluid piping systems are not to be
located in accommodation, service spaces, or control stations. The vent pipes of the
storage tank are to terminate in a safe location on the weather deck and the tank
venting system is to be arranged to prevent entrance of water into the tank for
chemical treatment fluids.
10.2.11 Storage tanks and piping systems for chemical treatment fluids which transfer
undiluted chemical treatment fluids are to be of steel or other equivalent material
with a melting point above 925°Celsius.
10.2.12 Storage tanks and piping systems for chemical treatment fluids are to be made with a
material compatible with the chemical treatment fluids, or coated with appropriate
anti-corrosion coating.
10.2.13 Regardless of design pressure and temperature, piping systems containing chemical
treatment fluids are to comply with the requirements applicable to Class I piping
systems.
10.2.15 For the protection of crew members, the ship is to have on board suitable personnel
protective equipment consisting of protective clothing, boots, gloves and
tight-fitting goggles. The amount of personnel protective equipment carried on board
is to be appropriate for the number of personnel engaged in regular handling
operations or that may be exposed in the event of a failure; but in no case are
there to be less than two sets available on board.
10.2.16 Eyewash stations and safety showers are to be provided; the location and number is to
be appropriate for the location of chemical treatment fluid systems on board. The
following locations are to be provided as applicable;
- transfer or treatment pump locations;
- chemical bunkering station on deck;
- system connections/components that require periodic maintenance; and
- any part of the system where a spillage/drainage may occur.
10.2.17 Storage tanks for chemical treatment fluids are to be arranged so that they can be
emptied of the fluids and ventilated by means of portable or permanent systems.
10.2.18 The holding tanks for residues generated from the exhaust gas cleaning process are to
satisfy the following requirements:
- The tanks are to be independent from other tanks, except in cases where
these tanks are also used as the overflow tanks for chemical treatment
fluids storage tank.
- Tank capacities are to be decided in consideration of the number and type of
installed exhaust gas cleaning systems as well as the maximum number of days
between ports where residue can be discharged ashore. In the absence of
precise data, a figure of 30 days is to be used.
- Where residue tanks used in closed loop chemical treatment systems are also
used as the overflow tanks for chemical treatment fluid storage tanks, the
requirements for storage tanks apply.
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