Segregation of incompatible containers on board container ships

This is in response to your October 10, 2007, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to vessel stowage. Specifically, you request clarification of § 176.83 for the segregation of incompatible containers on board container ships.

In your letter, you describe a scenario in which one container is stowed on deck and another container is stowed below deck in a closed versus closed situation and the incompatible containers are required to be segregated longitudinally by an intervening complete compartment or hold. It is your understanding that horizontal segregation is not required provided the containers are not stowed in the same vertical line and separated by a fire and liquid resistant bulkhead.

Your understanding is correct. The fore and aft segregation requirements need only be applied to incompatible containers when they are both on deck or when they are both under deck, unless otherwise stated.