- “H” class divisions – Bulkheads and decks that are constructed of steel or other equivalent material, suitably stiffened, and are designed to withstand and prevent the passage of smoke and flame for the 120-minute duration of a hydrocarbon fire test.
- “A” class divisions – Bulkheads and decks constructed of steel or other equivalent material, suitably stiffened, and designed to withstand and prevent the passage of smoke and flame for the duration of the one-hour standard fire test.
- “B” class divisions – Bulkheads, decks, ceilings or linings that are designed to withstandand prevent the passage of flame for at least the first half hour of the standard fire test.
- “C” class divisions – Divisions constructed of approved non-combustible materials.