Fire protection of steelwork

Abstract: The fire protection of steelwork requires insulation material to be fitted around any exposed steelwork. Typical steelwork comprises I-section rolled steel members, but the flange thickness can vary considerably in thickness. The present invention aims to provide a single push-on clip which can be fitted to the most commonly used flange sizes providing a simple but effective means of attaching fire protection material to steelwork. Accordingly, the clip according to the present invention comprises a length of wire which is bent to form a first abutment (limbs 3, 5) disposed immediate the ends of the length of the wire and which is further provided with a pair of second abutments (limbs 15, 22; 13, 28) connected to the first abutment by respective connecting limb portions (9, 11). The first and second abutments are adapted to engage opposite sides of a side flange of the steelwork. Twisting and/or bending of the wire allows the spacing between the first and second abutments to be adjusted to suit a particular flange dimension. Each second abutment is disposed between the first abutment and a respective free end (24, 32) of said length of wire, and wherein the wire beyond said second abutments is returned by one or more bends (20, 29) to provide two free ends which extend in two substantially perpendicular directions. When the clip is fitted to steelwork at least one of the free ends will project from the steelwork and provide a mounting post on which fire protection material can be impaled.

Description: The present invention relates to the fire protection of steelwork and in particular to a clip for fixing sheets of mineral fibre insulation board to steelwork. There is a requirement to fire protect steelwork in buildings using a fire resistant material. Typically, the steelwork to be protected comprises lengths of I-section steel which are typically vertical or horizontal, but not limited to same. The exposed surfaces of the steelwork has to be boxed in and one typical material is a soft mineral fibre board. Currently this is secured in place by one of two methods. In the first method mild steel pins (say 50mm long and 2mm diameter) are welded to the steelwork so as to project normal to the longitudinal axis of the steelwork. Pre-cut pieces of fibre board can then be pushed onto the pins, which pierce their way through the material thereby positioning the sheet of insulation along the sides of the steelwork. A spring retaining washer is applied to the projecting pin to hold the insulation in place. In order to weld the pins in place any protective paint applied to the steelwork has to be cleaned off and then replaced after welding in of the pins. The procedure is time consuming as the fitter has to work his way along the steelwork cleaning off and welding any pins before the insulation can be fixed in place. In the second method, fixing pieces of mineral fibre board are cut to fit between the flanges of the I-beam and glued in place. Then sheets of mineral fibre board to box in the steelwork are glued to the fixing pieces and further pieces secured to these to cover the flanges. Clearly this is particularly time consuming. US-A- 4043092 discloses a push fit clip for securing fire protection materials to steekwork. The clip is formed from a length of wire and has portions of wire which abut opposite sides of the flange. The opposite side abutting portion lead to a respective free end. A push-fit clip system of this general type using a spring steel clip to secure the insulation in place can only be fitted to a fairly small range of flange thicknesses (making several sizes obligatory to suit the application), and furthermore the clip could not be utilised where the beam was used to carry so-called "dovetail roof decking", since the limbs of the clip which would engage the upper surface of the beam was too wide to fit in the available space. This lead to the belief that a practical clip design was not possible and hence the adoption of the above-described fixing methods. The present invention aims to provide a solution to the above-mentioned problems. Accordingly, the present invention provides a clip for use in securing fire protection material to steelwork, the clip comprising a length of wire which has first and second free ends, at least one of which, in use, receives the material to be secured, and which length of wire is bent to form a first abutment disposed intermediate the said free ends of the length of wire, and wherein, in use, the first abutment engages one side of a flange of the steelwork, characterised in that the length of the wire is further bent to form a pair of second abutments connected to the first abutment by respective connecting limb portions, which second abutments, in use, engage the other side of said flange, a respective one of the pair of second abutments being disposed intermediate said first abutment and a respective one of said free ends of said length of wire, and wherein the wire beyond at least one of said second abutments has one or more bends so that, in use at least one of said free ends projects from the steelwork into a position to receive the material to be secured. In a preferred embodiment of the present invention, the wire beyond each second abutment is returned by one or more bends to dispose respective end limbs of the clip in substantially perpendicular planes whereby when clipped onto a flange one end limb is disposed in a plane generally parallel to the plane of the flange on which the clip is received and the other end limb is disposed generally perpendicularly thereto. More particularly, the first abutment comprises two limbs being joined by a common continuous bend, and preferably with an included angle in the range 5°-25°. This allows the first abutment to fit onto the flange within the space available with dovetail floor/roof decking. Alternatively, the two limbs may be formed by two discrete bends. The connection of the respective limbs of the first abutment with respective limbs of the second abutment is by way of two bends in the wire. Preferably the respective second abutments are disposed laterally outwardly of the first abutment. Conveniently as made, the limbs of the first and second abutment are disposed in the same plane. The angle of the respective bends is approximately 90°. Some variation is possible and may be a desirable option. The limbs of the first abutment and those of the second abutment extend in the same general direction from the respective connecting limbs therebetween. A hard drawn mild steel wire is preferred and the respective bends accommodate subsequent twisting without exceeding the plastic limit of the material. Thus, the number of bends and/or limbs and their length contributes to the range of flange thickness which can be accommodated. With the preferred construction the clip can be used with a flange thickness in the range 5-35mm, for example. The opposite outer surfaces of I-section steelwork as defined by the respective flanges are planar and normal to the central longitudinal web of the beam. However, the flanges may be tapered in cross-section and so their inner surfaces may lie in a plane which is inclined to the normal. This inclination is accommodated by twisting along the wire between the first and second abutments and especially at the bends themselves. The bends in the wire are advantageous in facilitating adjustment of the angle of the limbs on installation since the resultant angle of these prior to adjustment will be determined by the starting angle and the size of the flange to which the clip is fitted. Thus the fitter can adjust the orientation of the end limbs of the clip to be in the required perpendicular orientation after fitting onto the steelwork. In the case of the clip fitting onto the upper flange, the end limb is advantageously positioned offset downwardly from the plane of the flange and in a parallel plane. Covering material, for example fire protecting insulation, is fitted to structural steelwork using the aforesaid clips by pushing clips onto flanges of the steelwork at spaced positions along the length thereof so that at least one end limb of the clip projects beyond the widthwise extremity of the steelwork, and thereafter applying a precut sheet of soft material fibre board to the projecting end limbs hold the material in position. The preferred application of the invention is in respect of the fire protection of steelwork in which case the covering material is a fire protecting insulation material. Where the fire protecting insulation material is a soft mineral fibre board it can be simply pushed onto the projecting end limbs which pierce the material. It is not essential for the end limbs to project through the insulation, but where they do advantageously the projecting end limbs are bent over to positively retain the insulation. Alternatively spring washers may be fitted onto the projecting end limbs and pushed up to the insulation material. More particularly for a horizontal beam, having flanges disposed uppermost and lowermost, where only the two sides and the underside have to be fire protected, the same clips are employed for both flanges. The clips of the upper and lower flanges are applied in the same orientation, but this means that only one of the end limbs is used in the case of the clip attaching to the uppermost flange, whilst both end limbs are used for the clip attaching to the lowermost flange. Where the steelwork is to be completely encased, for example in the case of a vertical beam, the clips are applied to the flanges in opposite orientations so that both projecting end limbs are employed. Thus where both end limbs are to project for use the first abutment engages the inwardly facing surfaces of the flange, but where only one end limb is to project it engages the outer planar surface. The present invention will now be described further, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a plan view of a clip according to one aspect of the present invention, Figure 2 is a side view of the clip of Figure 1 viewed on arrow A, Figure 3 is an end view of the clip of Figure 1 viewed on arrow B, Figure 4 is a perspective view showing the clip of Figure 1 fitted on a flange of a steel beam, Figure 5 is a section through a steel beam showing an example of the clip in use, and Figure 6 is a perspective view of an alternative embodiment of clip according to the present invention. Referring to Figures 1, 2 and 3, a clip according to the present invention comprises a length of malleable hard drawn mild steel wire, typically about 450mm long and 3mm diameter although other lengths and diameters are feasible. The wire is bent in several places to form the desired shape and comprises a first bend 1 through say 165° to define the two limbs 3, 5 which are divergent with an included angle on the range 5°-25° and preferably of the order of 15°. The two limbs 3, 5 define a first abutment 7. From the ends of the two limbs the wire is bent through approximately 90° (see bends 16 and 18). This forms respective connecting limbs 9, 11 which connect the first abutment with respective second abutments defined by a respective second limbs 13, 15. Each second limb is formed by bending the wire through approximately 90° at the end of the connecting limbs 9, 11 and in the same direction from the connecting limbs as the limbs 3, 5. Thus bends 16, 17 and 18, 19 are formed. For convenience of manufacture the limbs 3, 5, 9, 11 and 13, 15 are in a common plane at this stage. At the end of the limb 15, the wire bends through 90° at 21, extends for a short distance to form an intermediate limb 22 and them bends through a further 90° at 20 to form a limb 23 which leads to one free end 24 of the length of wire. Limbs 22 and 23 are in substantially the same plane and limbs 15 and 23 are substantially parallel to one another. Limb 22 is inclined downwardly with respect to limb 11. Limb 23 extends to project beyond a plane accommodating the limbs 9, 11. At the end of limb 13, the wire bends through 90° at 27, extends a short distance to form an intermediate limb 28 and then bends through 90° at 29 in a perpendicular direction to extend in a direction away from the first abutment to form end limb 31 which leads to the other free end 32 of the wire. Thus, free ends 23 and 32 are disposed generally perpendicular to one another. Malleable hard drawn wire is preferred for the clip material because it allows the adjustment range to be accommodated, but more particularly it allows the limbs 23, 32 to be adjusted by the fixer. Limbs 15 and 22 may be replaced by one straight limb, with a corresponding alteration to the angle of bends, and similarly for limbs 13 and 28. Figure 4 shows the above clip received onto the flange F of a steel beam (not further illustrated) and it will be seen how limb 23 projects beyond the edge of the flange in a plane parallel to the plane of the flange and perpendicular to the plane of the web I. This is primarily achieved by twisting along limb 15 after the clip has been pushed home and more specifically at bend 19. Limb 31 extends perpendicularly to the plane of the flange, which orientation may be arrived at by physical bending after installation of the clip, principally at bend 29. Figure 5 shows how several clips are applied to an I-section steel beam I in order to apply fibre board insulation FB (shown in dotted outline) to two opposite sides and the underside. Thus, clips are applied to the opposed upper flanges 50, 52 and to the opposed lower flanges 54, 56, in the same relative orientation for each side for the illustrated example whereby the limb 23 comes into play for the clips located on the upper flanges, and the limbs 23 and 31 came into play for the lower flanges. The fibre board insulation is applied to the projecting free ends, and pierces same. Retention can be further ensured either by bending over the projecting ends of limbs 23, 31 or applying a spring fixing washer. For our preferred embodiment of clip to cover flange thickness of up to 35mm, we envisage the limbs being dimensioned as follows: Limbs 3, 5 40mm Limbs 9, 11 60mm Limbs 13, 15 30mm Limbs 22, 28 35mm Limb 23 80mm Limb 32 50mm Referring now to Figure 6. Here a modified clip is employed in which like reference numerals have been used to denote points corresponding to those described above and therefore not described further hereinafter. The differences arise at the end of the respective second abutments 13, 15. Thus, in the case of limb 13, the wire bends downwardly through 90° relative to the plane of limbs 3, 9, 13 at bend 29' to give end limb 31 with free end 32. Thus intermediate limb 28 is omitted. In the case of limb 15, bend 21' is in the opposite direction to bend 21 so that limb 22' is directed away from the first abutment rather than toward it. Limb 22' is bent at 20 as before to provide end limb 23 leading to free end 24. The clip functions in the same manner as that described above. Whilst the invention has been described with particular reference to installation of a soft fibre mineral board, the clips may also be used for a rigid insulation board, although for such an application holes will have to be drilled through the boards to receive the projecting ends of the clips. Indeed the clips may have more general application as it can be used wherever a material is to be secured to a flange, especially where the clip is required to provide fixing pins to project either perpendicular and/or parallel to the plane of the flanges.

Claims: A clip for use in securing fire protection material to steelwork, the clip comprising a length of wire which has first and second free ends (24, 32), at least one of which, in use, receives the material to be secured, and which length of wire is bent to form a first abutment (3, 5) disposed intermediate said free ends of the length of wire, and wherein, in use, the first abutment engages one side of a flange of the steelwork, and which length of wire is further bent to form a pair of second abutments (15, 22; 13, 28) connected to the first abutment by respective connecting limb portions (9, 11) which second abutments, in use, engage the other side of said flange, and wherein the wire beyond at least one of said second abutments has one or more bends (20; 29) so that, in use at least one of said free ends projects from the steelwork into a position to receive the material to be secured, characterized in that each one of the pair of second abutments being disposed intermediate said first abutment and a respective one of said free ends (24, 32) of said length of wire . A clip as claimed in claim 1, in which the wire beyond each second abutment (15, 22; 13, 28) has one or more bends (20; 29) to dispose respective end limbs of the clip in substantially perpendicular planes. A clip as claimed in claim 2, in which, when disposed on said flange, one end limb (23) is disposed in a plane generally parallel to the plane of the flange on which the clip is received and the other end limb (31) is disposed generally perpendicularly thereto. A clip as claimed in any one of the preceding claims, in which the first abutment (7) comprises two limbs (3,5) joined by a connecting portion (1) of the wire. A clip as claimed in claim 4, in which connection of a respective one of the respective limbs (3, 5) of the first abutment (7) with a respective limbs (15, 22; 13, 28) of the second abutments is by way of two bends (18, 19; 16, 17) of the wire. A clip as claim in claim 5, in which there is a said connecting limb (9, 11) portion between each of said two bends (18, 19; 10, 17) and wherein the limbs (3, 5; 13, 15) of the first and second abutments extend away from the connecting limbs. A clip as claimed in anyone of claims 1 to 3 or claim 4 when appendent to any one of claims 1 to 3, in which the second abutments are disposed laterally outwardly of the first abutment. A clip as claimed in claim 7, in which, as made, the limbs (3, 5, 13, 15) of the first and second abutments are disposed in the same plane. A clip as claimed in anyone of claims 2 to 8, in which the angle of the respective bends (19, 20, 21; 17, 27, 29) is approximately 90°. A clip as claimed in claim 2 or any one of claims 3 to 8 when the appendent to claim 2 in which one end limb (31) is connected to the second abutment by a single bend (29) to position it at substantially 90° to the second abutment from which it depends, and the other end limb (23) is returned outwardly from the second abutment from which it depends so that the second abutment and at least part of the other end limb lie in a substantially common plane. A clip as claimed in anyone of the preceding claims when made from a hard drawn mild steel wire.

Inventors: DISON JOHN MICHAEL, DISON JULIAN MARK, DISON, JOHN MICHAEL, DISON, JULIAN MARK
Applicants: CAFCO EUROP GROUP S A, GORDON & CO LTD H, CAFCO EUROPE GROUP S.A., H. GORDON & CO. LIMITED
Application year: 1996
Main classification: E04B1
IPC codes: E04B1, F16B2