however, where ducts

however, where ducts pass through spaces surrounded by "A" class divisions, without serving those
spaces, provided those ducts have the same fire integrity as the divisions which they pierce.
D.5.7.6 Ventilation ducts with a free cross-sectional area exceeding 0.02 m2 passing through "B" class
bulkheads shall be lined with steel sheet sleeves of 900 mm in length divided preferably into 450 mm on
each side of the bulkheads unless the duct is of steel for this length.
D.5.8 Insulation of duct penetrations
The fire protection insulation of air ducts and sleeves is to be in accordance with the space group pairings
indicated in tables, see GL Rules for Hull Structures (I-1-1), Section 22, Table 22.1 to 22.8.
The tables relating to the bulkhead are likewise applicable to ducts routed through decks.
A space pairing refers to the spaces separated by a bulkhead or deck, irrespective of any other spaces
served by the duct in question.