15.8.1 Products transported under the provisions of this section shall be acetylene-free.
15.8.2 Unless cargo tanks are properly cleaned, these products shall not be carried in tanks
which have contained as one of the three previous cargoes any products known to catalyse
polymerization, such as:
- mineral acids (e.g. sulphuric, hydrochloric, nitric);
- carboxylic acids and anhydrides (e.g. formic, acetic);
- halogenated carboxylic acids (e.g. chloracetic);
- sulphonic acids (e.g. benzenesulphonic);
- caustic alkalis (e.g. sodium hydroxide, potassium hydroxide);
- ammonia and ammonia solutions;
- amines and amine solutions; and
- oxidizing substances.
15.8.3 Before loading, tanks shall be thoroughly and effectively cleaned, to remove all traces of
previous cargoes from tanks and associated pipework, except where the immediately prior cargo
has been propylene oxide or ethylene oxide/propylene oxide mixtures. Particular care shall be
taken in the case of ammonia in tanks made of steel other than stainless steel.
15.8.4 In all cases, the effectiveness of cleaning procedures for tanks and associated pipework
shall be checked by suitable testing or inspection, to ascertain that no traces of acidic or alkaline
materials remain that might create a hazardous situation in the presence of these products.
15.8.5 Tanks shall be entered and inspected prior to each initial loading of these products to
ensure freedom from contamination, heavy rust deposits and visible structural defects. When
cargo tanks are in continuous service for these products, such inspections shall be performed at
intervals of not more than two years.
15.8.6 Tanks for the carriage of these products shall be of steel or stainless steel construction.
15.8.7 Tanks for the carriage of these products may be used for other cargoes after thorough
cleaning of tanks and associated pipework systems by washing or purging.
15.8.8 All valves, flanges, fittings and accessory equipment shall be of a type suitable for use
with the products and shall be constructed of steel or stainless steel in accordance with
recognized standards. Discs or disc faces, seats and other wearing parts of valves shall be made
of stainless steel containing not less than 11% chromium.
15.8.9 Gaskets shall be constructed of materials which do not react with, dissolve in, or lower
the autoignition temperature of these products and which are fire-resistant and possess adequate
mechanical behaviour. The surface presented to the cargo shall be polytetrafluoroethylene
(PTFE), or materials giving a similar degree of safety by their inertness. Spirally wound stainless
steel, with a filler of PTFE or similar fluorinated polymer, may be accepted.
15.8.10 Insulation and packing, if used, shall be of a material which does not react with, dissolve
in, or lower the autoignition temperature of these products.
15.8.11 The following materials are generally found unsatisfactory for gaskets, packing and
similar uses in containment systems for these products and would require testing before being
approved by the Administration:
- neoprene or natural rubber, if it comes into contact with the products.
- asbestos, or binders used with asbestos.
- materials containing oxides of magnesium, such as mineral wools.
15.8.12 Threaded joints shall not be permitted in the cargo liquid and vapour lines.
15.8.13 Filling and discharge piping shall extend to within 100 mm of the bottom of the tank or
any sump pit.
126.96.36.199 The containment system for a tank containing these products shall have a valved
188.8.131.52 The products shall be loaded and discharged in such a manner that venting of the tanks
to atmosphere does not occur. If vapour return to shore is used during tank loading, the vapourreturn
system connected to a containment system for the product shall be independent of all other
184.108.40.206 During discharge operations, the pressure in the cargo tank must be maintained above
0.007 MPa gauge.
15.8.15 The cargo may be discharged only by deepwell pumps, hydraulically operated
submerged pumps, or inert-gas displacement. Each cargo pump shall be arranged to ensure that
the product does not heat significantly if the discharge line from the pump is shut off or
15.8.16 Tanks carrying these products shall be vented independently of tanks carrying other
products. Facilities shall be provided for sampling the tank contents without opening the tank to
15.8.17 Cargo hoses used for transfer of these products shall be marked "FOR ALKYLENE OXIDE TRANSFER ONLY".
15.8.18 Cargo tanks, void spaces and other enclosed spaces adjacent to an integral gravity cargo
tank carrying propylene oxide shall either contain a compatible cargo (those cargoes specified in
15.8.2 are examples of substances considered incompatible) or be inerted by injection of a
suitable inert gas. Any hold space in which an independent cargo tank is located shall be inerted.
Such inerted spaces and tanks shall be monitored for these products and oxygen. The oxygen
content of these spaces shall be maintained below 2%. Portable sampling equipment is
15.8.19 In no case shall air be allowed to enter the cargo pump or piping system while these
products are contained within the system.
15.8.20 Prior to disconnecting shore-lines, the pressure in liquid and vapour lines shall be
relieved through suitable valves installed at the loading header. Liquid and vapour from these
lines shall not be discharged to atmosphere.
15.8.21 Propylene oxide may be carried in pressure tanks or in independent or integral gravity
tanks. Ethylene oxide/propylene oxide mixtures shall be carried in independent gravity tanks or
pressure tanks. Tanks shall be designed for the maximum pressure expected to be encountered
during loading, conveying and discharging cargo.
220.127.116.11 Tanks for the carriage of propylene oxide with a design pressure less than 0.06 MPa
gauge and tanks for the carriage of ethylene oxide/propylene oxide mixtures with a design
pressure of less than 0.12 MPa gauge shall have a cooling system to maintain the cargo below the
18.104.22.168 The refrigeration requirement for tanks with a design pressure less than 0.06 MPa
gauge may be waived by the Administration for ships operating in restricted areas or on voyages
of restricted duration, and account may be taken in such cases of any insulation of the tanks. The
area and times of year for which such carriage would be permitted shall be included in the
conditions of carriage of the International Certificate of Fitness for the Carriage of Dangerous
Chemicals in Bulk.
22.214.171.124 Any cooling system shall maintain the liquid temperature below the boiling
temperature at the containment pressure. At least two complete cooling plants, automatically
regulated by variations within the tanks, shall be provided. Each cooling plant shall be complete
with the necessary auxiliaries for proper operation. The control system shall also be capable of
being manually operated. An alarm shall be provided to indicate malfunctioning of the
temperature controls. The capacity of each cooling system shall be sufficient to maintain the
temperature of the liquid cargo below the reference temperature of the system.
126.96.36.199 An alternative arrangement may consist of three cooling plants, any two of which shall
be sufficient to maintain the liquid temperature below the reference temperature.
188.8.131.52 Cooling media which are separated from the products by a single wall only shall be
nonreactive with the products.
184.108.40.206 Cooling systems requiring compression of the products shall not be used.
15.8.24 Pressure-relief-valve settings shall not be less than 0.02 MPa gauge and for pressure
tanks not greater than 0.7 MPa gauge for the carriage of propylene oxide and not greater than
0.53 MPa gauge for the carriage of propylene oxide/ethylene oxide mixtures.
220.127.116.11 The piping system for tanks to be loaded with these products shall be separated (as
defined in 3.1.4) from piping systems for all other tanks, including empty tanks. If the piping
system for the tanks to be loaded is not independent (as defined in 1.3.18), the required piping
separation shall be accomplished by the removal of spool-pieces, valves, or other pipe section
and the installation of blank flanges at these locations. The required separation applies to all
liquid and vapour piping, liquid and vapour vent lines and any other possible connections, such
as common inert-gas supply lines.
18.104.22.168 These products may be transported only in accordance with cargo-handling plans that
have been approved by the Administration. Each intended loading arrangement shall be shown
on a separate cargo-handling plan. Cargo-handling plans shall show the entire cargo piping
system and the locations for installation of blank flanges needed to meet the above piping
separation requirements. A copy of each approved cargo-handling plan shall be maintained on
board the ship. The International Certificate of Fitness for the Carriage of Dangerous Chemicals
in Bulk shall be endorsed to include reference to the approved cargo-handling plans.
22.214.171.124 Before each initial loading of these products and before every subsequent return to
such service, certification verifying that the required piping separation has been achieved shall be
obtained from a responsible person acceptable to the port Administration and carried on board
the ship. Each connection between a blank flange and a pipeline flange shall be fitted with a wire
and seal by the responsible person to ensure that in-advertent removal of the blank flange is
126.96.36.199 No cargo tanks shall be more than 98% liquid-full at the reference temperature.
188.8.131.52 The maximum volume to which a cargo tank shall be loaded is:
= maximum volume to which the tank may be loaded
V = volume of the tank
= density of cargo at the reference temperature
= density of cargo at the loading temperature and pressure
184.108.40.206 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 to be approved by the Administration. A copy of the list shall be
permanently kept on board by the master.
15.8.27 The cargo shall be carried under a suitable protective padding of nitrogen gas. An
automatic nitrogen make-up system shall be installed to prevent the tank pressure falling below
0.007 MPa gauge in the event of product temperature fall due to ambient conditions or
maloperation of refrigeration systems. Sufficient nitrogen shall be available on board to satisfy
the demand of the automatic pressure control. Nitrogen of commercially pure quality (99.9% by
volume) shall be used for padding. A battery of nitrogen bottles connected to the cargo tanks
through a pressure-reduction valve satisfies the intention of the expression "automatic" in this context.
15.8.28 The cargo tank vapour space shall be tested prior to and after loading to ensure that the
oxygen content is 2% by volume or less.
15.8.29 A water-spray system of sufficient capacity shall be provided to blanket effectively the
area surrounding the loading manifold, the exposed deck piping associated with product
handling, and the tank domes. The arrangement of piping and nozzles shall be such as to give a
uniform distribution rate of 10 l/m2
/min. Remote manual operation shall be arranged such that
remote starting of pumps supplying the water-spray system and remote operation of any normally
closed valves in the system can be carried out from a suitable location outside the cargo area,
adjacent to the accommodation spaces and readily accessible and operable in the event of fire in
the areas protected. The water-spray system shall be capable of both local and remote manual
operation, and the arrangement shall ensure that any spilled cargo is washed away. Additionally,
a water hose with pressure to the nozzle, when atmospheric temperatures permit, shall be
connected ready for immediate use during loading and unloading operations.
15.8.30 A remotely operated, controlled closing-rate, shutoff valve shall be provided at each
cargo-hose connection used during cargo transfer.