Fire doors, fire dampers and structural fire protection

The divisions and how they are rated

SOLAS II-2/3 defines the classes. An “A” class division is steel or equivalent, suitably stiffened, insulated with approved non-combustible materials so that the average temperature on the unexposed side rises no more than 140°C, and no single point more than 180°C, within 60, 30, 15 or 0 minutes for A-60, A-30, A-15 and A-0, and it must stop smoke and flame to the end of the one-hour standard fire test. A “B” class division is non-combustible, with an average rise of no more than 140°C and 225°C at any point for 15 minutes (B-15) or 0 minutes (B-0), and stops flame to the end of the first half hour. Prototypes are tested to the Fire Test Procedures (FTP) Code, 2010, Part 3, which also covers fire dampers, windows, pipe penetrations and cable transits (Appendix 2). Fire door control systems are tested under Part 4.

The required rating between two spaces comes from the SOLAS II-2/9 tables (9.1 to 9.8), which depend on ship type and on the two spaces’ fire risk categories. Passenger ships are divided into main vertical zones by A class bulkheads; cargo ships use one of the protection methods IC, IIC or IIIC for accommodation. The approved fire plan and structural fire protection plan show the result for your ship.

Penetrations and insulation

• Penetrations of A class divisions must be tested to the FTP Code, except steel pipes of at least 3 mm wall and 900 mm length without openings, insulated like the division.
• Insulation is carried past penetrations, intersections and ends for at least 450 mm.
• Uninsulated metal pipes through A-0 or B-0 divisions must melt above 950°C (A-0) or 850°C (B-0).
• Repairs and alterations must keep at least the previous standard (SOLAS II-2/1.3).

Fire doors

Passenger ships: doors in main vertical zone bulkheads, galley boundaries and stairway enclosures (other than power-operated watertight doors and normally locked doors) must:

• close themselves against an inclination of up to 3.5°;
• close in about 10 to 40 seconds (hinged) or at 0.1 to 0.2 m/s (sliding) with the ship upright;
• be released remotely from the continuously manned central control station, in groups or all together, and individually from both sides;
• have no hold-back hooks that the central station cannot release;
• re-close automatically after being opened locally, and close automatically if the control system or power fails;
• have local power accumulators for at least ten full openings and closings after power failure;
• show at the fire door panel whether each door is closed;
• (sliding and power-operated) sound an alarm 5 to 10 seconds before moving and until closed.

Cargo ships: door fire resistance must equal the division’s; A class doors and frames of steel; B class doors non-combustible; doors in boundaries of category A machinery spaces reasonably gastight and self-closing; self-closing doors without hold-back hooks, though fail-safe remotely released hold-backs may be used. In corridor bulkheads, ventilation openings up to 0.05 m² are allowed in the lower half of cabin doors.

Fire dampers and ducts

For ships built on or after 1 January 2016 (resolution MSC.365(93)):

• Automatic fire dampers are required in ducts with a free cross-section over 0.075 m² passing through A class divisions, fitted close to the division, closing automatically but also manually from both sides, with a visible position indicator.
• All fire dampers must be manually operable from both sides; automatic dampers must have a fail-safe mechanism that closes them on loss of electric, hydraulic or pneumatic power; remotely operated dampers must be re-openable manually at the damper.
• Dampers must be easily accessible. Dampers behind ceilings or linings need an inspection hatch marked with the damper’s identification number, and that number must also be on any remote control.
• Ducts need inspection and cleaning hatches near the dampers, and the main inlets and outlets must be closable from outside the space, with marked operating positions.
• Ducts of 0.02 m² to 0.075 m² through A class divisions get steel sleeves at least 3 mm thick and 900 mm long, insulated to the division’s rating.

Inspection and testing (MSC.1/Circ.1432)

During rounds, also look at: door closers and seals, latches that engage by themselves, doors not wedged or tied back, damper indicators readable and in the open position in normal service, damper hatches marked and openable, penetrations not disturbed, insulation intact in machinery and stairway casings, and no new openings in the boundaries of CO2-protected spaces.