Many a time vessel’s officers and shore side stowage planners have different interpretation for loading dangerous goods and reefers sighting sources of ignition and heat.

Which are the potential sources of ignition and heat on board ships?

Here we are interpreting the provisions of IMDG Code, readers are welcome to comment with their interpretation of the Code.

Stowage in relation to Sources of Ignition

Certain dangerous goods require distance to be maintained from sources of ignition while stowing on board ships and this requirement differs from type of ships

• Potential sources of ignition means, but is not limited to, open fires, machinery exhausts, galley uptakes, electrical outlets and electrical equipment including those on refrigerated or heated cargo transport units unless they are of certified safe type. (Certified type: For cargo spaces, refer to SOLAS II-2/19.3.2 and for refrigerated or heated cargo transport units refer to Recommendations published by the International Electrotechnical Commission, in particular IEC 60079.)

Class 1 Explosives: shall not be stowed within a horizontal distance of 6 m from potential sources of ignition.

Class 2.1 and 3: Container with flammable gases or with flammable liquids having a flashpoint of less than 23°C c.c transported on deck shall be stowed at least 2.4 m from any potential source of ignition.

On Container Ships Live reefer or electrically heated tanks that is not of a certified safe type shall not be stowed under deck together with containers containing flammable gases or with liquids having a flashpoint of less than 23°C c.c.

On Ro-Ro Vessels containers with flammable gases or liquids having a flashpoint of less than 23°C c.c. and transported on deck shall be stowed at least 3 m from any potential sources of ignition.

On General Cargo Ships Flammable gases or liquids having a flashpoint less than 23°C c.c. transported on deck shall be stowed at least 3 m from any potential source of ignition.

Stowage in relation to Sources of Heat

Stowage code SW1 requires packages to be “Protected from sources of heat.”

Example UN Number 1555 ARSENIC BROMIDE Class 6.1 is assigned with stowage code SW1 which means this cargo must be protected from sources of heat.

• Protected from sources of heat means that packages and cargo transport units shall be stowed at least 2.4 m from heated ship structures, where the surface temperature is liable to exceed 55°C. Examples of heated structures are steam pipes, heating coils, top or side walls of heated fuel and cargo tanks, and bulkheads of machinery spaces. In addition, packages not loaded inside a cargo transport unit and stowed on deck shall be shaded from direct sunlight. The surface of a cargo transport unit can heat rapidly when in direct sunlight in nearly windless conditions and the cargo may also become heated. Depending on the nature of the goods in the cargo transport unit and the planned voyage precautions shall be taken to ensure that exposure to direct sunlight is reduced.

Are reefers source of heat?

No, reefers are not a source of heat however when large number of reefers are stowed together it may be considered as source of heat especially when packed with chilled cargo.

Further reading

Stowage and Segregation of Dangerous Goods on Container Ships