2.1 “A” Class Bulkheads
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Statutory Documents - IMO Publications and Documents - Resolutions - Assembly - IMO Resolution A.754(18) – Recommendation on Fire Resistance Tests for “A”, “B” and “F” Class Divisions – (Adopted on 4 November 1993) - Annex - Recommendation on Fire Resistance Tests for “A”, “B” and “F” Class Divisions1 - 2 Nature of Test Specimens - 2.1 “A” Class Bulkheads

2.1 “A” Class Bulkheads

Parent topic: 2 Nature of Test Specimens

2.1.1 Dimensions

 The minimum overall dimensions for the test specimen are given in SOLAS Regulation II-2/3.2, but the recommended dimensions of the test specimen, including the perimeter details at the top, bottom and vertical edges, are 2,440 mm width and 2,500 mm height.

 The overall dimensions of the structural core should be 20 mm less in both the width and the height than the overall dimensions of the specimen, and the other dimensions of the structural core should be as follows:

- thickness of plating: steel 4.5 ± 0.5 mm
    aluminium 6.0 ± 0.5 mm
- stiffeners spaced at 600 mm: steel 65 ± 5 x 65 ± 5 x 6 ± 1 mm
    aluminium 100 ± 5 x 75 ± 5 x 9 ± 1 mm

 The width of the structural core may be greater than the specified dimensions providing that the additional width is in increments of 600 mm to maintain the stiffener centres and the relationship between the stiffeners and the perimeter detail.

 Any joints in the plating should be full welded, at least from one side.

 The construction of a structural steel core having the recommended dimensions is shown in Figure 1; the thickness of the plating and dimensions of the stiffeners shown are nominal dimensions. Irrespective of the dimensions of the structural core and the material of manufacture, the details around the perimeter should be as illustrated in Figure 3.

Figure 1 Structural steel core for `A' class bulkhead and `B' class lining

Figure 2 Structural steel core for `A' class deck and `B' class ceiling

Figure 3 Connection between restraint frame and structural steel core

2.1.2 Design

 Where insulation is provided by panels (e.g. a "B" class lining), then the test specimen should be designed such that at least one of the panels is of full width and this, or these, should be positioned such that both its/their longitudinal edges are jointed to an adjacent panel and are not secured to the restraint frame. The overall dimensions of the panel insulation system, including the perimeter details at all the edges, should be 20 mm greater in each direction than the equivalent dimensions of the structural core.

 If the insulation system is a lining which may incorporate electrical fittings, e.g. light fittings and/or ventilation units, it is necessary that initially a test is performed on a specimen of the lining itself, without the incorporation of these units, to establish the basic performance. A separate test(s) may be performed on a specimen(s) with the units incorporated to ascertain their influence on the performance of the lining.

2.1.3 Description

 The applicant should provide full constructional details of the test specimen in the form of drawings (including a detailed schedule of components) and method of assembly, such that the laboratory is able to confirm agreement between the actual specimen and the drawings and specifications prior to the test. The drawings should include dimensions and details of the thicknesses of insulation used in way of the plating and the stiffeners, the method of securing the insulation system and details of the components used for this purpose, details of joints, connections, air gaps and all other details.

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