This invention relates to fire- resisting cladding for partitions or ducting or the like structures, particularly - but not exclusively - partitions or ducting formed of metal.

It is known to apply fire-resisting material by spraying on to a metal structure to form an adhering coating. However, because of differential expansion (and contraction) between the metal and the fire-resisting material, extreme temperature changes in-situ (especially high temperatures from fire or hot gas) can result in the fire-resisting material coating cracking off the metal.

Therefore, it is known to provide a mesh covering for the fire-resisting material coating to retain it in place.

Unless the mesh is particularly rigid (which makes it difficult to conform to a three-dimensional shape) it is difficult to maintain the integrity of the coating on prefabricated lengths of ducting during handling and transporting.

It is also known to form partition panels as sandwiches of fire resisting material (usually in fibrous form) between perforated steel sheets, but this sandwich construction is heavy and requires numerous connectors between the steel sheets to hold them to the fire-resisting material and also to maintain the spacing of the steel sheets so that they cannot crush the material between them when such panels are stacked for storing.

An object of the present invention is to provide a method of cladding a structure with fire-resisting material to overcome or appreciably alleviate the aforesaid

disadvantages.

Another object is to apply a method as aforesaid to the cladding of a steel partition, or a steel panel for use in the construction of a partition.

A further object is to apply a method as aforesaid to the cladding of a length of steel ducting.

The invention also embraces structures, steel panels and partitions, and steel ducting, all clad with fire- resisting material by the method of the invention.

According to the present invention, a method of cladding a structure with fire-resisting material comprises securing structural wire mesh to a basic structure, applying fire-resisting material through the mesh to cause the material to adhere to the basic structure, and continuing application of the material until a coating is built up reinforced by the mesh.

The structural steel mesh reinforcing the coating maintains its integrity at all times and especially during handling and transporting of prefabricated fire-resisting cladded structures made in accordance with the invention.

By "structural wire mesh" is meant a mesh formed by wires in parallel planes connected together by further wires extending between those planes and secured to the wires therein to consitute a self-supporting load-bearing structure. An example of such a mesh is known as VOLUNET (registered trade mark) originating from N.V.Bekaert S.A. and comprising longitudinal and transverse steel wires in pairs of parallel planes welded to undulating steel wires disposed therebetween Although strong, the mesh can be

comparatively light in relation to the weight of the basic structure, yet provide reinforcement and protection for the fire-resisting material. Decorative panelling or other finishing material may be secured to the structural wire mesh.

Steel structural wire mesh can be welded to a basic steel structure, such as a panel or partition (e.g., a bulkhead), but any structural wire mesh may be secured to any basic structure by clips, bolts or other fasteners. If the basic structure is a length of ducting then portions of structural wire mesh can be secured together round the ducting (or directly thereto) to form a cage whereby the mesh is effectively secured to the ducting.

However, the structural wire mesh is preferably spaced from the basic structure, particularly if it is a steel panel or partition, or steel ducting, to prevent or greatly reduce possible conduction of heat from the structure to the mesh. Spacing means may comprise a plurality of spaced devices, such as washers on studs, or lugs extending from bolting flanges, or channel-sections or angle-irons, or saddles, to which the structural wire mesh may be secured (if necessary) by spot-welding.

The fire-resisting material may be applied by spraying, and spraying is preferably continued until the thickness of coating at least equals the overall thickness of the structural wire mesh, but may be continued until the coating is thicker and completely envelopes the mesh. Alternatively, the fire-resisting material may be applied by pumping in behind shuttering spaced from the wire mesh.

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whereby the coating of fire-resisting material will be thicker than and will inevitably completely envelope the mesh.

A suitable fire-resisting material is available from Mandoral Coatings Limited under the designation P20, and its curing time can be modified to suit the manner of application (spraying or pumping behind shuttering), the thickness and the extent of the coating being built up.

Exposed corners of fire-resisting material coating may be provided with additional reinforcement, such as longitudinally bent lengths of expanded metal mesh.

Any gaps or crevices between adjoining prefabrica ed cladded structures made in accordance with the invention can be readily filled by injecting some of the fire-resisting material into them, or bolting flanges between adjoining lengths of ducting clad in accordance with the invention can be coated with some of the fire-resisting material after they have been bolted together.

Methods according to the invention, and embodiments of cladded structures resulting therefrom will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figures 1 to 3 are fragmentary sections through a steel panel or partition showing stages in one method of applying fire-resisting cladding in accordance with the invention;

Figures 4 to 6 correspond to Figures 1 to 3, but show different ways of finishing off a cladded steel panel or partition in accordance with the invention;

Figure 7 also corresponds to the preceding drawings but shows a different method of applying fire-resisting cladding in accordance with the invention;

Figure 8 is a sectional view across square ducting clad with reinforced fire-resisting material in accordance with the invention;

Figure 9 is a fragmentary section on the line IX-IX in Figure 8, showing similar lengths of ducting bolted together ;

Figure 10 corresponds to Figure 8 but shows rectangular ducting with different spacing means from that shown in Figure 8 for the structural wire mesh;

Figure 11 is a fragmentary section on the line XI-XI in Figure 10, and similar to Figure 9;

Figure 12 corresponds to a part of Figure 10 showing the same spacing means used to create a greater spacing of the mesh from the ducting;

Figure 13 is a fragmentary section on the line XIII- XIII in Figure 12; and

Figure 14 is a fragmentary perspective view showing a portion of VOLUNET as an example of structural wire mesh.

Figure 1 shows a basic structure 20 comprising a steel panel (or partition) and spacing means 21 consisting of studs 22 welded to the panel and washers 23 pushed on to the studs to a uniform extent, ready to space from the steel panel a structural wire mesh 24 as shown in Figure 2, which mesh can be secured to the panel by welding of the mesh to the spacing means.

In Figures 2 to 13 inclusive the structural wire mesh

is represented very diagrammatically, but should be understood to consist of wires in parallel planes connected together by further wires extending between those planes and secured to the wires therein. The further wires could be individual lengths, or elongate lengths bent into simple zig-zag form or into the form of the wires 25 in Figure 14.

Figure 3 shows fire-resisting material 26 being sprayed, initially through the mesh 24 to cause the material to adhere to the basic structure 20, and continuing until a coating is built up reinforced by the mesh 24.

The spraying can be terminated before all the mesh is completely enveloped by the fire-resisting material and, as shown in Figure 4, decorative panels 27 can be secured to the structural wire mesh, e.g., by spring clips (not shown) or, as shown in Figure 5, a rendering 28 can be applied to cover the otherwise exposed wires.

Preferably, however, spraying is continued until the thickness of the coating 26 exceeds the overall thickness of the mesh 24 (i.e., including the spacing means 21, or taken from the basic structure 20), so that the mesh 24 is completely enveloped in the fire-resisting material 26, as shown in Figure 6.

Alternatively, the fire-resisting matrial 26 can be applied, as shown in Figure 7, by pumping in behind shuttering 29 spaced from the mesh 24, whereby the coating of fire-resisting material 26 will be thicker than and will inevitably completely envelope the mesh 24.

In Figures 8 and 9 square steel ducting 30 has a bolting flange 31 at each end of each length, only one end

being shown, and the flanges are provided with spacing means

21 in the form of lugs for spaced location of portions 24 of structural wire mesh which are secured together round the ducting to form a cage whereby the mesh is effectively secured to the ducting, and fire-resisting material 26 has been applied (as by spraying, or by pumping in behind shuttering) until the mesh is enveloped by the material 26, corner reinforcements 32 being included additionally, either before application of the material 26 commences or - if sprayed - as application progresses towards the outer planes of the mesh. When two lengths of ducting have been bolted together, as in Figure 9, the bolting flanges (and the nuts and bolts) can be coated with some of the fire-resisting material 26, as is also shown in Figure 9.

In Figures 10 and 11 rectangular steel ducting 40 also has a bolting flange 31 at each end of each length, again only one end being shown, and spacing means 21 comprises channel-sections extending longitudinally with their bases 41 against the ducting to present the flanges 42 as ribs for location of portions 24 of structural wire mesh which are secured together to form a cage round the ducting. In all other respects the cladded ducting of Figures 10 and 11 is similar to that of Figures 8 and 9.

Figures 12 and 13 show each channel-section spacing means 21 disposed with one flange 42 abutting the ducting so that the other flange 42 is disposed at a distance determined by the width of the base 41 and which is greater than that determined by the height of the flanges 42 in the disposition shown in Figures 10 and 11.