What is stowage?
Stowage means the proper placement of dangerous goods on board a ship in order to ensure safety and environmental protection during transport. Stowage requirements are different for containerships, ro-ro ships, general cargo ships and barge-carrying ships.
Stowage requirement is assigned through stowage “categories” in column 16a of Dangerous Goods List in chapter 3.2 of IMDG Code. Stowage categories permits on deck or under deck stowage, on deck only or prohibition on passenger ships..
- For explosives stowage categories are 01 to 05
- For dangerous goods other than explosives stowage categories are A to E
Stowage categories for class 1 Explosives
Stowage categories for classes 2 to 9
All dangerous goods are assigned with stowage categories and certain dangerous goods are assigned with stowage and / or handling codes in dangerous goods list column 16a which must be complied with.
- Stowage Code SW1 Protected from sources of heat.
- Handling Code H2 Keep as cool as reasonably practicable.
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What is Segregation?
Segregation is the process of separating two or more substances or articles which are considered mutually incompatible when their packing or stowage together may result in undue hazards in case of leakage or spillage, or any other accident. Segregation is obtained by maintaining certain distances between incompatible dangerous goods or by requiring the presence of one or more steel bulkheads or decks between them, or a combination thereof.
Incompatibilities between two dangerous goods can be either dangerous reaction when they come in contact with each other (Example 1) or there will be no dangerous reactions but together when involved in fire the magnitude of fire and subsequent damages can be catastrophic (Example 2).
- Example 1: Cyanides will dangerously react with acids
- Example 2: Chlorodinitrobenzenes will not react with flammable liquids but may explode if involved in a fire.
Four Terms for Segregation
There are four terms used for segregating incompatible goods and application of these terms differs for different types of ships and for packing containers.
- “away from”;
- “separated from”;
- “separated by a complete compartment or hold from”;
- “separated longitudinally by an intervening complete compartment or hold from”.
How do we separate incompatible goods for safe segregation?
Separation between goods can be achieved by increasing the distance between the goods or loading them in different cargo holds. The process of maintaining distance between goods or separating them is different for containerized goods and non-containerized goods.
Provisions for segregation includes: General Provisions, Segregation Table, Segregation Groups, Special segregation provisions, Exemptions, Segregation of goods of class 1 and Segregation Codes.
Below are the relevant chapters of IMDG Code for stowage and segregation on different types of ships.
- Chapter 7.1 General stowage provisions
- Chapter 7.2 General segregation provisions
- Chapter 7.3 Consigning operations concerning the packing and use of cargo transport units (CTUs) and related provisions
- Chapter 7.4 Stowage and segregation on containerships
- Chapter 7.5 Stowage and segregation on ro-ro ships
- Chapter 7.6 Stowage and segregation on general cargo ships
- Chapter 7.7 Shipborne barges on barge-carrying ships
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