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IMO A635

IMO FTPC Part 5 and 6 / IMO Res. 653 (16)

IMO Resolution A.653 (16) and A.687(17)

This recommendation specifies a procedure for measuring fire characteristics of bulkhead, ceiling and deck finish materials as a basis for characterizing their surface flammability, and thus their suitability for use in marine constructions. IMO Res. A.687(17) describes how specimens of primary deck coverings shall be prepared, tested and assessed according to the method described in IMO Res. A.653(16).


A specimen with dimensions 0,795 m x 0,145 m is exposed in vertical position to a graded radiant heat flux field supplied by a gas-fired radiant panel. The angle between the specimen and the radiant panel is 150.

The distribution of the heat flux field along the specimen is calibrated at fixed positions 100 mm apart. The values of the heat flux field at these positions as specified in the standard are between 1,5 and 50,5 kW/m2.

Gases given off from the specimen are ignited by a pilot flame from a burner which is situated at the end of the specimen which is nearest to the radiant panel. The combustion gases are drawn off through a fume stack above the specimen.


The test report contains information about:

  • Composition of the product
  • Name of the product
  • Manufacturer and place of production
  • Heat for sustained combustion, Qsb.
  • Critical heat for extinguishment, CFE.
  • Total heat release and peak heat release rate, Qt og qp.
  • Classification of the product

The criteria for low spread of flame is given below.


The specimens shall be representative of the product, and as far as possible be similar to the final product. A complete test requires that at least 5 specimens are available.

Dimensions of the specimens:

Area: 145 mm x 795 mm
Thickness: maximum 50 mm

Primary deck covering to be tested according to IMO Res. A.687(17) shall be applied in the thickness used in practice to an underlay of steel plate with thickness 3 ± 0,3 mm.


Testing can be started when order is confirmed in writing, and the test specimens have been conditioned according to the method description. Normally it will last 3-4 weeks from we have received the test specimens until the test report is finished.


The criteria are related to average values of the test results.


Burning drops
Criteria to surface materials³ 20,0³ 1,5£ 0,7£ 4,0Not allowed
Criteria to floorings³ 7,0³ 0,25£ 2,0£ 10,0Max 10

CFE = critical flux at extinguishment
Qsb = heat for sustained burning
Qt = total heat release
qp = peak heat release rate

Critical flux at extinguishment (CFE):

A flux level at the specimen surface corresponding to the distance of farthest advance and subsequent self-extinguishment of the flame on the centreline of a burning specimen. The flux reported is based on a calibration test with a dummy specimen.

Heat for sustained burning (Qsb):

The product of time [s] from initial specimen exposure until arrival of the flame front at each 150 mm interval along the specimen and the incident flux level [kW/m2] at the same location as measured with a dummy specimen during calibration. The longest time used in this calculation should correspond to flame arrival at least 30 mm prior to the position of furthest flame propagation on the centreline of the specimen.

Heat release of specimen:

The observed heat release under the variable flux field imposed on the specimen and measured as defined by the test.