GB2335481A

GB2335481A - Fire protective system

Info

Publication number: GB2335481A
Application number: GB9913202A
Authority: GB
Inventors: Anthony Snowdon
Original assignee: Darchem Engineering Ltd
Current assignee: Darchem Engineering Ltd
Priority date: 1995-05-16
Filing date: 1996-05-15
Publication date: 1999-09-22
Anticipated expiration: 2016-05-15
Also published as: GB9913203D0; GB9913202D0; GB2335482A; GB2335482B; GB2335481B

Abstract

A fire protective system for fire proofing a device, comprises layers 16,20,24 of compressible non-combustible material, fasteners 28 for holding the layer in a compressed state at ambient temperatures but allowing the layer to expand at elevated temperatures, and an outer protective layer comprising heat-resistant and erosion-resistant wire mesh 32 having a melting temperature above 1000‹C. The outer protective layer of erosion resistant mesh is operably positioned outwardly from the fasteners 28 with respect to the device being protected.

Description

1 FIRE PROTECTIVE SYSTEM 2335481 The invention relates to a system for

providing fire protection of devices such as p es, pipeline equipment, electrical conductors, control systems and electrical ip 1 motors. Systems of this type provide thermal insulation for the enclosed item, protecting, it from the extreme temperatures of a fire.

C Known systems for providing fire proofing comprise several layers of resilient compressible material which are non-combustible and held in a compressed configuration, in use, by fasteners having a low heat resistance. In the event of fire, the fasteners break or otherwise disintegrate thereby allowing the compressed material to expand to its normal state. The compressible insulating material can, for example, be a blanket of inorganic fibre such as ceramic fibre, aluminium silicate fibre, or glass fibre. The layers of compessed material are supported by an outer scrim layer which is positioned on the outside and inside face of the layers of compressible material and held against the faces by the ends of the fasteners. The fasteners comprise end plates which abut the scrim layers, and a spindle which extends between the plates to maintain the compressible material in a compressed configuration.

It is known to use nylon or glass fibre for example as a scrim layer. Also, it is known to provide outermost layers above both the fastener and scrim which are 2 reflective, beinú, made of aluminium or silver thereby to reflect radiant heat, andlor weatherproof. However, it is found that this type of fire protective system cannot provide adequate protection against directionally applied heat, for example from a jet of fire. In these conditions it is possible for the temperature at the protective layers to be held in the order of 120TC, for example due to a propane fire jet, over an extended period of time. Under these conditions, known systems of insulating materials are found to disintegrate relatively quickly thereby failing to provide fire proofing over an extended period of time such as two hours.

c Objects of the invention are to avoid or at least mitigate problems of the prior art to provide improved fire proofing against jet fires and, for example, to provide a fire protective system which can withstand a jet fire of 1200C for a period of about two hours.

L According to one aspect of the invention, there is provided a fire protective System for fire proofing a device, comprising a layer of compressible, non-combustible matenal such as cerajlu'c fibres, means for holding the layer in a compressed state at ambient temperatures, an outer protective layer comprising heat-resistant and erosion-resistant wire mesh having a melting temperature above 1000'C, and preferably above 1200'C and wherein the holding means is independent of the outer protective layer. A suitable wire mesh is made of stainless steel, such as SS316, which can comprise of 0.2 min.

3 Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fiaure 1 is a cross-sectional view of part of a layered fire protection system 0 according to the invention; and Figure 2 is a cross-sectional view of part of a second fire protection system according to the invention.

Referring to Figure 1, there is shown a fire protection system (10) comprising an innermost layer (12) which can be made of silicone-coated glass cloth for example.

0 This layer is used to abut the device, such as a pipe or electrical conductor for example, which is being protected.

:0 A scrim layer is then provided which can be a glass cloth. The smim abuts a first layer (16) of compressible non-combustible material such as an inorganic fibre blanket, organic fibre blanket, organic foam, ceramic fibre, aluminium silicate fibre, or glass fibre for example. In the case of ceramic fibre, aluminium silicate fibre, or glass fibre, a polymeric binder such as phenolic can be used to help restore the fibres to their original density after release of a compressive force.

4 A layer (18) such as alurniinium foil is used to separate layer (16) from a second compressible layer (20). Layer (20) can be made of any of the materials just described in relation to layer (16). A further thin layer (22) is used to separate compressible layer (20) from a sirluilar layer (24) which again can be made of any of the materials described in relation to layer (16). An outer scri'm layer (26) made of glass cloth is also provided.

The compressible layers (16,20,24) are held in a compressed state, in use, using a fastener (28) having end plates and a central spindle which act together with the scrim layers (14,16). Of course, a pluraliry of fasteners is provided as is known in the art in order to construct large sheets of fire insulating material. As is also known, part of fastener (29) has a relatively low heat resistance such that, in the event of a fire near a device insulated using system (10), fastener (28) breaks, thus allowing layers (16,20,24) to expand thereby to provide greater heat insulation to the protected device.

However, additional protective layers are provided in Figure 1 compared to the known art, and these comprise a layer (30) which can be made of carbon fibre cloth and a layer (32) of heat resistant and erosion resistant material such as wire mesh. For example, the wire mesh can be made of stainless steel such as Grade 316 for applications in corrosive environments such as on an offshore oil rig. The mesh preferably comprises 0.2= diameter wire formed into a mesh having 0.3= square or 0.2mm by 0.4mm rectangular openings. Variations of plus or M. 1nus 10% on these dimensions are tolerable.

An outermost layer (34) can be provided in order to effect weatherproofing of the system. For example, the outer skin can be made of a silicone-coated glass cloth.

In a second embodiment accordina to the.invention, a system (36) is provided as 0 shown in Figure 2. In this embodiment only a heat-resistant and mechanically strong layer (32) is used since layer (30) is dispensed with.

Of course, any number of layers of compressible non-combustible materials can be used. However, in the preferred form, the number is three and they are made of ceramic fibre of 25mm, thickness at 96kg per in' density. Also, in the preferred embodiment, the silicone-coated glass cloth used for layers (12,34) is of the 3200-2-SS type whilst layers (18,22,26,38) are preferably made of 0.002 inch (0.05 mm) thick alurninium. foil. Layers (14,26), the scrim layers, are preferably made of alass fibre such as Marglass 400 having a weave lock finish. Fasteners (28) can be made from a retention pin and washer made of plastic wherein the pin has a 0. 5mrn diameter and is 45mrn long.

The overall system can be formed into blankets which are fastened along their edges and ends, preferably using stainless steel wire. A simple hoop stitching can be used 6 in one or more rows along the edges. The stitching usefully provides means for attaching the mechanically strong layer (32) such as mesh to the compressible layers. Blankets and collars of layered system (10,36) can be fitted to electrical devices or piping which it is desired to protect using known techniques and connections.

Accordingly, in use, the compressed layers are wrapped about a system in a known manner. However, using the system (10,36) according to the invention, much greater heat resistance is provided than from known systems in the event of a directional fire, such as from a jet of propane gas for exarnple. In these circumstances, a high temperature can be experienced at the surface of the system, for example in the order of 120TC, and additionally, it has been found that a jet creates considerable physical forces on the system which have the effect of creating mechanical and erosive stresses which might break down the system, removing the insulation for example, thus rendering its thermal insulation properties useless. However, the system (10,36) can withstand such highly directional fires, since an outer layer (32) such as steel mesh which is mechanically strong and erosion-resistant at high temperatures acts to prevent damage to the outside of the system - other than the disintegration of weatherproof layer (34) which is in any event enfirely sacrificial. Layer (32) of course, allows some heat to pass to pins (28) thereby to allow layers (16,20,24,40) to expand but it provides mechanical resistance to stabilize the system against the disruptive force of a jet of fire.

7 The action of layer (30) is also found to be useful in this regard in preventing breakdown of inner layers (24) and (26) or layers (40) and (26) for example.

b 8 CLANS 1. A fire protective system for fire proofing a device. comprising a layer of compressible, non-combustible material, means for holding the layer in a compressed state at ambient temperatures but allowing the layer to expand at elevated temperatures, and an outer protective layer comprising heat-resistant and erosion-resistant wire mesh having a melting temperature above 1000T, and wherein the outer protective layer of erosion resistant material is operably positioned outwardly from the fasteners with respect to the device being protected.

A fire protective system according to claim 1 wherein the melting temperature of the outer layer is above 120WC.

3. A fire protective system according to claim 1 or 2 wherein the outer protective layer is a wire mesh which does,not erode by more than 0.05 mm an hour when impacted upon by a jet of fire such as a propane fire jet at sonic velocities and at 12000C.

4. A fire protective system according to claim 1, 2 or 3 wherein the wire mesh is made of stainless steel, such as SS316.

5. A fire protective systern according to claim 1, 2, 3 or 4 wherein the wire diameter is about 0.2 mm.

9 6. A fire protective system according to any preceding claim comprising a scrim c layer.

7. A fire protective system according to claim 6 wherein the scri'm layer comprises glass cloth.

8. A fire protective system according to any preceding claim comprising two or more layers of compressible non-combustible matenial--- 9. A fire protective system according to claim 8 wherein each layer of compressible non-combustible matexial is separated from an adjacent layer by a separating layer such as aluminium foil.

a 10. A fire protective system according to any preceding claim wherein the holding means comprises heat breakable fasteners for compressing the layer, or layers, of compressible non-combustible material.

11. A fire protective system according to any preceding claim comprising an inner layer for abutting the device to be protected, comprising silicone-coated glass cloth.

12. A fire protective system according to any preceding claim comprising an outermost sacrificial layer of physically durable but relatively combustible material such as silicone-coated glass cloth.

13. A fire protective system substantially as described herein with reference to Fiaure 1.

c 14. A fire protective system substantially as described herein with reference to Figure 2.