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Segregation and stowage requirements for dangerous cargo - IMDG code guideline

Handling dangerous cargo requires special care due to the inherent hazardous nature of the cargo and applicable carriage regulations.The general provisions for segregation between the various classes of dangerous goods are shown in "Segregation table" (IMDG Code Chapter In addition to the general provisions, there may be a need to segregate a particular substance, material or article from other goods which could contribute to its hazard.

IMDG code & related guideline -IMDG Code means International Maritime Dangerous Goods Code . Transport of dangerous goods by sea is regulated by IMDG Code in order to prevent injury to persons or damage to ships and their cargoes. Transport of marine pollutants is primarily regulated to prevent harm to the marine environment.

The objective of the IMDG Code is to enhance the safe transport of dangerous goods while facilitating the free unrestricted movement of such goods. The IMDG Code contains details of all the numerous dangerous cargoes offered for carriage by sea and includes solid, liquid and gaseous substances. Explosive, flammable, oxidising and radioactive substances are also included and recommended means of their containment or packing are listed, as is all manner of other information relating to the product. Future updating of the Code, on two-year basis, are foreseen in order to take into account technological developments.

All ships carrying dangerous cargoes should have on board medical first-aid equipment, including oxygen resuscitation equipment and antidotes for cargo carried in compliance with recommendations listed in IMO -–MFAG (Medical First Aid Guide) and WHO – IMGS (International Medical Guide for Ships).

D/G Cargo “Onboard” List

Where required for reporting to port authorities, the C/Off shall prepare an updated dangerous cargo list. This list shall contain at least the following information: a) Stow Position b) Container Number c) Line Operator
d) Port of Loading / Discharging e) DG Class f) UN Number
g) Proper Shipping Name h) Weight i) Flash Point and EMS
Such list for reporting to authorities shall be made with utmost caution.

D/G Cargo Stowage Plan

The C/Off shall prepare a copy of the Dangerous Cargo Stowage Plan (indicating D/G class & Stowage Location), along with a D/G Cargo List (indicating Location, Cntr No., D/G Class and UN No.).

And these along with any special guidelines from shippers, shall be kept:
- in Wheel House (for ready reference of the watch keeping officer) and
- in Fire Wallets at Gangways.

Stowage Hold or Container (enclosed)

Before loading any Dangerous Goods into a compartment or container, it should be ascertained that the space is suitable for that particular cargo and that it is in a good dry condition.

All Dangerous Goods should be tightly stowed and well secured against any movement including chafe. Securing materials used should be compatible with the goods themselves.

Drums should be stowed close and compact, bungs or closures uppermost. Rolling hoops should not override. Adequate soft dunnage (e.g. timber) should be laid between tiers­even, in some instances, though the drums are designed to "nest". With drums of sensitive cargo, e.g. chlorates, bromates, chlorites and substances in other classes such as nitrocellulose, it may be necessary to dunnage individually between each drum.

Whenever Dangerous Goods and general cargo are stowed within the same compartment or container, the Dangerous Goods should be stowed (where possible) for best accessibility and to facilitate inspection, e.g. in the doorway of the container.

It is important to remember that the presence of even one package of Dangerous Goods in a container at once renders that container hazardous and subject to Dangerous Goods legislation.

Particular provisions for segregation are indicated in the Dangerous Goods List and, in the case of conflicting provisions, always take precedence over the general provisions. For example:

a) In the Dangerous Goods List entry for ACETYLENE, DISSOLVED, class 2.1, UN 1001, the following particular segregation requirement is specified:
“separated from” chlorine

“separated from” acids
( IMDG Code Chapter )

containerized  dangerous goods need special care while underway
typical arrangement of tank container
Tank container with DG cargo

2. Where the Code indicates a single secondary hazard (one subsidiary risk label), the segregation provisions applicable to that hazard should take precedence where they are more stringent than those of the primary hazard.
( IMDG Code Chapter )

3. Except for class 1, the segregation provisions for substances, materials or articles having more than two hazards (2 or more subsidiary risk labels) are given in the Dangerous Goods List.

For example:

In the Dangerous Goods List entry for BROMINE CHLORIDE, class 2.3 UN 2901, subsidiary risk 5.1 and 8, the following particular segregation is specified:

“segregation as for class 5.1 but “separated from “class 7”
* (IMDG Code Chapter )

4. Whenever dangerous goods are stowed together, whether or not in a cargo transport unit, the segregation of such dangerous goods from others should always be in accordance with the most stringent provisions for any of the dangerous goods concerned.
(IMDG Code Chapter )

5. No segregation need be applied between dangerous goods of different classes which comprise the same substance but vary only in their water content, such as sodium sulphide in classes 4.2 and 8, or for class 7 if the difference is due to quantity only.
(IMDG Code Chapter

6. Notwithstanding IMDG Code Chapter, and, substances of the same class may be stowed together without regard to segregation required by secondary hazards (subsidiary risk label(s)), provided the substances do not react dangerously with each other and cause:

.1 combustion and/or evolution of considerable heat;
.2 evolution of flammable, toxic or asphyxiant gases;
.3 the formation of corrosive substances; or
.4 the formation of unstable substances.
(IMDG Code Chapter

Remark: As a general rule to carry these substances in same cargo transport unit, this regulation should not be applied priority over Chapter, and without surveyor’s clarified assess that there is not the above danger due to mixing these substances.

7. Dangerous goods which have to be segregated from each other should not be carried in the same cargo transport unit. However, dangerous goods which should be segregated “away from” each other may be carried in the same cargo transport unit with the approval of the competent authority. In such cases an equivalent standard of safety must be maintained.
(IMDG Code Chapter

8. For the purpose of segregation, dangerous goods having certain similar chemical properties have been grouped together in segregation groups as listed in The entries allocated to these segregation groups are listed in IMDG Code chapter Where in the Dangerous Goods List entry in column 16 (stowage and segregation) a particular segregation requirement refers to a group of substances, such as "acids", the particular segregation requirement applies to the goods allocated to the respective segregation group.
(IMDG Code Chapter

*Segregation groups referred to in the Dangerous Goods List* (IMDG Code Chapter

.1 acids
.2 ammonium compounds
.3 bromates
.4 chlorates
.5 chlorites
.6 cyanides
.7 heavy metals and their salts
.8 hypochlorites
.9 lead and lead compounds
.10 liquid halogenated hydrocarbons
.11 mercury and mercury compounds
.12 nitrites
.13 perchlorates
.14 permanganates
.15 powdered metals
.16 peroxides
.17 azides
.18 alkalis

9. It is recognized that not all substances falling within a segregation group are listed in this Code by name. These substances are shipped under N.O.S. entries. Although these N.O.S. entries are not listed themselves in the above groups, the shipper shall decide whether allocation under the segregation group is appropriate. Mixtures, solutions or preparations containing substances falling within a segregation group and shipped under an N.O.S. entry are also considered to fall within that segregation group.
(IMDG Code Chapter

10. The segregation groups in this Code do not cover substances which fall outside the classification criteria of this Code. It is recognised that some non-hazardous substances have similar chemical properties as substances listed in the segregation groups. A shipper or the person responsible for packing the goods into a cargo transport unit who does have knowledge of the chemical properties of such non-dangerous goods may decide to implement the segregation requirements of a related segregation group on a voluntary basis.
(IMDG Code Chapter

Procedures and guidelines for dangerous cargo documentation
Documents relating to dangerous (DG) cargo on board are subject to scrutiny by port officials, PSC inspectors and other concerned parties. Thus any irregularities in such documentation may result in fines, detention or other such serious implications for the vessel. ....

Procedures and guidelines for dangerous cargo handling
Every dangerous cargo shipment shall be made in line with IMO policy and be accompanied by required documentation. DG cargo with restricted/prohibited UN numbers shall not be accepted for shipment unless under special circumstance express permission is obtained from the company. ....

Handling of Harmful Packaged goods
Annex III Marpol 73/78 (Harmful Substances carried at Sea in Packaged Form : This Annex came into force internationally on 1July 1992. It contains regulations which include requirements on packaging, marking, labelling, documentation, stowage and quantity limitations....

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