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15.9 Sodium chlorate solution (50% or less by mass)
15.9.1 Tanks and associated equipment, which have contained this product may be used for other cargoes after thorough cleaning by washing or purging.
15.9.2 In the event of spillage of this product, all spilled liquid shall be thoroughly washed away without delay. To minimize fire risk, spillage shall not be allowed to dry out.
15.10 Sulphur (molten)
15.10.1 Cargo tank ventilation shall be provided to maintain the concentration of hydrogen sulphide below one half of its lower explosive limit through-out the cargo tank vapour space for all conditions of carriage (i.e. below 1.85% by volume).
15.10.2 Where mechanical ventilation systems are used for maintaining low gas concentrations in cargo tanks, an alarm system shall be provided to give warning if the system fails.
15.10.3 Ventilation systems shall be so designed and arranged as to preclude depositing of sulphur within the system.
15.10.4 Openings to void spaces adjacent to cargo tanks shall be so designed and fitted as to prevent the entry of water, sulphur or cargo vapour.
15.10.5 Connections shall be provided to permit sampling and analysing of vapour in void spaces.
15.10.6 Cargo temperature controls shall be provided to ensure that the temperature of the sulphur does not exceed 155℃.
15.10.7 Sulphur (molten) has a flashpoint above 60℃; however, electrical equipment shall be certified safe for gases evolved.
15.11 Acids
15.11.1 The ship's shell plating shall not form any boundaries of tanks containing mineral acids.
15.11.2 Proposals for lining steel tanks and related piping systems with corrosion-resistant materials may be considered by the Administration. The elasticity of the lining shall not be less than that of the supporting boundary plating.
15.11.3 Unless constructed wholly of corrosion-resistant materials or fitted with an approved lining, the plating thickness shall take into account the corrosivity of the cargo.
15.11.4 Flanges of the loading and discharge manifold connections shall be provided with shields, which may be portable, to guard against the danger of the cargo being sprayed; and in addition, drip trays shall also be provided to guard against leakage on to the deck.
15.11.5 Because of the danger of evolution of hydrogen when these substances are being carried, the electrical arrangements shall comply with 10.1.4. The certified safe type equipment shall be suitable for use in hydrogen/air mixtures. Other sources of ignition shall not be permitted in such spaces.
15.11.6 Substances subjected to the requirements of this section shall be segregated from oil fuel tanks, in addition to the segregation requirements in 3.1.1.
15.11.7 Provision shall be made for suitable apparatus to detect leakage of cargo into adjacent spaces.
15.11.8 The cargo pump-room bilge pumping and drainage arrangements shall be of corrosion-resistant materials.
15.12 Toxic products
15.12.1 Exhaust openings of tank vent systems shall be located:
.1 at a height of B/3 or 6 m, whichever is greater, above the weather deck or, in the case of a deck tank, the access gangway;
.2 not less than 6 m above the fore-and-aft gangway, if fitted within 6 m of the gangway;
.3 15 m from any opening or air intake to any accommodation and service spaces; and
.4 the vent height may be reduced to 3 m above the deck or fore-and-aft gangway, as applicable, provided high-velocity vent valves of an approved type, directing the vapour/air mixture upwards in an unimpeded jet with an exit velocity of at least 30 m/s, are fitted.
15.12.2 Tank venting systems shall be provided with a connection for a vapour-return line to the shore installation.
15.12.3 Products shall:
.1 not be stowed adjacent to oil fuel tanks;
.2 have separate piping systems; and
.3 have tank vent systems separate from tanks containing non-toxic products.
15.12.4 Cargo tank relief-valve settings shall be a minimum of 0.02 MPa gauge.
15.13 Cargoes protected by additives
15.13.1 Certain cargoes with a reference in column o in the table of chapter 17, by the nature of their chemical make-up, tend, under certain conditions of temperature, exposure to air or contact with a catalyst, to undergo polymerization, decomposition, oxidation or other chemical changes. Mitigation of this tendency is carried out by introducing small amounts of chemical additives into the liquid cargo or controlling the cargo tank environment.
15.13.2 Ships carrying these cargoes shall be so designed as to eliminate from the cargo tanks and cargo-handling system any material of construction or contaminants which could act as a catalyst or destroy the inhibitor.
15.13.3 Care shall be taken to ensure that these cargoes are sufficiently protected to prevent deleterious chemical change at all times during the voyage. Ships carrying such cargoes shall be provided with a certificate of protection from the manufacturer, and kept during the voyage, specifying:
.1 the name and amount of additive present;
.2 whether the additive is oxygen-dependent;
.3 date additive was put in the product and duration of effectiveness;
.4 any temperature limitations qualifying the additives' effective lifetime; and
.5 the action to be taken shall the length of voyage exceed the effective lifetime of the additives.
15.13.4 Ships using the exclusion of air as the method of preventing oxidation of the cargo shall comply with 9.1.3.
15.13.5 A product containing an oxygen-dependent additive shall be carried without inertion (in tanks of a size not greater than 3,000 m3). Such cargoes shall not be carried in a tank requiring inertion under the requirements of SOLAS chapter II-2*.
15.13.6 Venting systems shall be of a design that eliminates blockage from polymer build-up. Venting equipment shall be of a type that can be checked periodically for adequacy of operation.
15.13.7 Crystallization or solidification of cargoes normally carried in the molten state can lead to depletion of inhibitor in parts of the tank's contents. Subsequent remelting can thus yield pockets of uninhibited liquid, with the accompanying risk of dangerous polymerization. To prevent this, care shall be taken to ensure that at no time are such cargoes allowed to crystallize or solidify, either wholly or partially, in any part of the tank. Any required heating arrangements shall be such as to ensure that in no part of the tank does cargo become overheated to such an extent that any dangerous polymerization can be initiated. If the temperature from steam coils would induce overheating, an indirect low-temperature heating system shall be used.
15.14 Cargoes with a vapour pressure greater than 0.1013 MPa absolute at 37.8℃
15.14.1 For a cargo referenced in column o in the table of chapter 17 to this section, a mechanical refrigeration system shall be provided unless the cargo system is designed to withstand the vapour pressure of the cargo at 45℃. Where the cargo system is designed to withstand the vapour pressure of the cargo at 45℃, and no refrigeration system is provided, a notation shall be made in the conditions of carriage on the International Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk to indicate the required relief-valve setting for the tanks.
15.14.2 A mechanical refrigeration system shall maintain the liquid temperature below the boiling temperature at the cargo tank design pressure.
15.14.3 When ships operate in restricted areas and at restricted times of the year, or on voyages of limited duration, the Administration involved may agree to waive requirements for a refrigeration system. A notation of any such agreement, listing geographic area restrictions and times of the year, or voyage duration limitations, shall be included in the conditions of carriage on the International Certificate of Fitness for the Carriage of Dangerous Chemicals in Bulk.
15.14.4 Connections shall be provided for returning expelled gases to shore during loading.
15.14.5 Each tank shall be provided with a pressure gauge which indicates the pressure in the vapour space above the cargo.
15.14.6 Where the cargo needs to be cooled, thermometers shall be provided at the top and bottom of each tank.
15.14.7.1 No cargo tanks shall be more than 98% liquid-full at the reference temperature (R).
15.14.7.2 The maximum volume (VL) of cargo to be loaded in a tank shall be:
Where V = volume of the tank
ρR = density of cargo at the reference temperature (R)
ρL = density of cargo at the loading temperature
15.14.7.3 The maximum allowable tank filling limits for each cargo tank shall be indicated for each loading temperature which may be applied, and for the applicable maximum reference temperature, on a list approved by the Administration. A copy of the list shall be permanently kept on board by the master.
15.15 Cargoes with low ignition temperature and wide flammability range
Deleted.
15.16 Cargo contamination
15.16.1 Deleted.
15.16.2 Where column o in the table of chapter 17 refers to this section, water shall not be allowed to contaminate this cargo. In addition, the following provisions apply:
.1 Air inlets to pressure/vacuum-relief valves of tanks containing the cargo shall be situated at least 2 m above the weather deck.
.2 Water or steam shall not be used as the heat-transfer media in a cargo temperature control system required by chapter 7.
.3 The cargo shall not be carried in cargo tanks adjacent to permanent ballast or water tanks unless the tanks are empty and dry.
.4 The cargo shall not be carried in tanks adjacent to slop tanks or cargo tanks containing ballast or slops or other cargoes containing water which may react in a dangerous manner. Pumps, pipes or vent lines serving such tanks shall be separate from similar equipment serving tanks containing the cargo. Pipelines from slop tanks or ballast lines shall not pass through tanks containing the cargo unless encased in a tunnel.
15.17 Increased ventilation requirements
For certain products, the ventilation system as described in 12.1.3 shall have a minimum capacity of at least 45 changes of air per hour, based upon the total volume of space. The ventilation system exhaust ducts shall discharge at least 10 m away from openings into accommodation spaces, work areas or other similar spaces, and intakes to ventilation systems, and at least 4 m above the tank deck.
15.18 Special cargo pump-room requirements
For certain products, the cargo pump-room shall be located on the deck level or cargo pumps shall be located in the cargo tank. The Administration may give special consideration to cargo pump-rooms below deck.
15.19 Overflow control
15.19.1 The provisions of this section are applicable where specific reference is made in column o in the table of chapter 17, and are in addition to the requirements for gauging devices.
15.19.2 In the event of a power failure on any system essential for safe loading, an alarm shall be given to the operators concerned.
15.19.3 Loading operations shall be terminated at once in the event of any system essential for safe loading becoming inoperative.
15.19.4 Level alarms shall be capable of being tested prior to loading.
15.19.5 The high-level alarm system required under 15.19.6 shall be independent of the overflow-control system required by 15.19.7 and shall be independent of the equipment required by 13.1.
15.19.6 Cargo tanks shall be fitted with a visual and audible high-level alarm which complies with 15.19.1 to 15.19.5 and which indicates when the liquid level in the cargo tank approaches the normal full condition.
15.19.7 A tank overflow-control system required by this section shall:
.1 come into operation when the normal tank loading procedures fail to stop the tank liquid level exceeding the normal full condition;
.2 give a visual and audible tank-overflow alarm to the ship's operator; and
.3 provide an agreed signal for sequential shutdown of onshore pumps or valves or both and of the ship's valves. The signal, as well as the pump and valve shutdown, may be dependent on operator's intervention. The use of shipboard automatic closing valves shall be permitted only when specific approval has been obtained from the Administration and the port State authority concerned.
15.19.8 The loading rate (LR) of the tank shall not exceed:
where U = ullage volume (m3) at operating signal level;
t = time(s) needed from the initiating signal to fully stopping the cargo flow into the tank, being the sum of times needed for each step in sequential operations such as operator's responses to signals, stopping pumps and closing valves;
and shall also take into account the pipeline system design pressure.
15.20 Alkyl (C7-C9) nitrates, all isomers
15.20.1 The carriage temperature of the cargo shall be maintained below 100℃ to prevent the occurrence of a self-sustaining, exothermic decomposition reaction.
15.20.2 The cargo may not be carried in independent pressure vessels permanently affixed to the vessel's deck unless:
.1 the tanks are sufficiently insulated from fire; and
.2 the vessel has a water deluge system for the tanks such that the cargo temperature is maintained below 100℃ and the temperature rise in the tanks does not exceed 1.5℃ per hour for a fire of 650℃.
15.21 Temperature sensors
Temperature sensors shall be used to monitor the cargo pump temperature to detect overheating due to pump failures.
* For equivalency arrangements for the carriage of styrene monomer, see MSC/Circ.879 and MSC/Circ.879/Corr.1
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