(a) The configurations listed in this paragraph refer to the separation of the cargo from its surroundings and list the various degrees of segregation required. Paragraphs and (2) of this section explain the symbols used in lines 1 and 2, in order, under the tank segregation column of Table 151.05.
(1) Segregation of cargo from surrounding waters (Line 1 of Table 151.05).
i = Skin of vessel (single skin) only required. Cargo tank wall can be vessel's hull.
ii = Double skin required. Cargo tank wall cannot be vessel's hull.
NA = Nonapplicable for this case. Independent tanks already have such segregation built in through design.
(2) Segregation of cargo space from machinery spaces and other spaces which have or could have a source of ignition (Line 2 of Table 151.05).
i = Single bulkhead only required. Tank wall can be sole separating medium.
ii = Double bulkhead, required. Cofferdam, empty tank, pumproom, tank with Grade E Liquid (if compatible with cargo) is satisfactory.
(c) If a cofferdam is required for segregation purposes and a secondary barrier is required for low temperature protection by § 151.15-3(d)(4), the void space between the primary and secondary barriers shall not be acceptable in lieu of the required cofferdam.