3.6 Heat transmission analysis
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1319 – Recommendation for the Evaluation of Fire Performance and Approval of Large Fire Doors – (11 June 2009) - Annex – Recommendation for the Evaluation of Fire Performance and Approval of Large Fire Doors - 3 Doors larger than those in section 1 above, but not exceeding 50% in surface area - 3.6 Heat transmission analysis

3.6 Heat transmission analysis

  3.6.1 By carrying out finite element calculations, the histories over time of the heat transmission within the structural assembly are computed and the temperature is compared with the temperature experienced by the assembly represented in the standard fire test.

  3.6.2 Based on suitable data for the temperature-dependent variables, an iterative procedure is used for the evaluation of thermal-mechanic properties.

  3.6.3 The thermal boundary conditions of convecting and radiative type are:

and

where:

qc and qr : Convective and radiative heat flux, respectively
hc : Convective heat transfer coefficient
σ: Stefan-Boltzmann constant
∊: Emissivity coefficient
Ts Surface temperature
T∞ Furnace or ambient temperature.

  3.6.4 The two equations can be included in an equivalent boundary condition:

where:

the equivalent coefficient Heq depends on the unknown surface temperature. However, it can be calculated as part of the finite element analysis using an emissivity coefficient appropriately calibrated with the fire test results.

  3.6.5 The equivalent heat transfer coefficient can be assumed to be constant on the single exposed surface, as the furnace assembly built in accordance with the FTP Code gives uniformity of the temperature and heat flux within the furnace.

  3.6.6 Alternatively, the temperature distribution measured on the specimen of the standard fire test can be directly applied on the finite element structural model taking into account the same time histories.

Parent topic: 3 Doors larger than those in section 1 above, but not exceeding 50% in surface area
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