Fire classification

In marine and offshore installations, requirement to fire resistance for the ceiling may be specified. The most common is B0 or B15 class, according to IMO Res.A.754 (18).

To complete the facility, light and ventilation are needed for the rooms. Those installations require cut outs (recess) in the ceiling elements, which concern the ceiling fire classification.

A recessed unit has to be constructed from approved non-combustible materials in accordance with relevant requirements of SOLAS Ch.II-2Reg.3 and intention of 31 and 47.

The lighting fixture as a separate unit cannot be fire approved. It is the complete installation with the covering of the installed unit that have to withstand the fire load.

When completing the installation you have to have in mind:

  • Fire rating for ceiling installation
  • The maximum allowed size of recess in the actual ceiling
  • Maximum weight of fixtures/units
  • Minimum allowed distance between recesses
  • Recess construction
  • Method of fixing
  • Type of panels the lighting fixture will be accepted onto: Width and length of panel, Thickness of panel, thickness of steel, plate, etc.

The installation on a vessel or a rig will never be exactly as the laboratory test installation. In practice there will be a mixing of cut out for lighting and ventilation as well as ceiling hatches. It is therefore very important to have in mind the minimum allowed distance between recess for the actual ceiling, as well as the maximum allowed load for each ceiling element.For B0 there is no temperature reduction requirements, but no tongue of fire is allowed to enter the unexposed side during the test period of 30 minutes. This means that, even the fixture is made of steel with no hole or slots in the body, the area between fixtures and ceiling is very important to keep in mind, in order to avoid any gap where the fire can enter.

For other B- and F-classes (B15/B30) there is requirement for insulation. This means that the insulation covering the fixture/ recessed unit must have the same rating as the ceiling element. Insulation boxes or matting are to be used. A ceiling element will bend down very much when exposed to high temperatures. A stiff insulation

cap will not follow the same form, and therefore the area between ceiling and covering insulation also in this aspect is very important to keep in mind.

According to IMO Res.A.754(18), the performance criteria to “A”,”B”and “F” class ceilings are:

CriteriaA-class B-class F-class 
Testing duration60 minutes30 minutes 30 minutes 
Insulation/Temperature rise: Average140°C140°C140°C
Maximum180°C 225°C 225°C 
Class description0, 15, 30, 600, 15, 30 30 

  • Integrity: The following requirements shall also be satisfied for the test duration.
  • Flaming: There shall be no flaming on the unexposed face
  • Cotton wool pad: There shall be no warm gases that can ignite a standardised cotton wool pad 
  • Gap gauges: By use of a gap meter, control that no gap more than 6 mm wide and 150 mm long, or single opening with diameter more than 25 mm exist.