METHOD OF PROTECTING AN OBJECT AGAINST FIRE AND FIRE PROTECTIVE COVERING FOR AN OBJECT

Abstract

The invention relates to a method of protecting an object (1) against fire. An endothermic material (2) is arranged around the object (1), and then an outer metal-containing cladding (5) is arranged so that it covers at least a part of the endothermic material (2). The endothermic material (2) is provided as a tape (3) which is applied by helically winding the tape (3) in an overlapping manner resulting in a stepped outer surface (6) facing towards the outer cladding (5). The outer cladding (5) comprises metal, in particular is made of metal. The stepped outer surface (6) results in air cavities (7) being formed underneath the outer cladding (5). When the object (1) is exposed to a fire, such small air cavities (7) will allow for a slight swelling of the endothermic material (2) that will, as a consequence of the fire, react and release water directly to the outer cladding (5) from underneath and thereby provide cooling thereof.

Claims

1. A method of protecting an object against fire, the method comprising: arranging an endothermic material around the object so that it covers at least a part of the object, and arranging an outer cladding covering at least a part of the endothermic material, wherein the endothermic material provided as a tape which is applied by helically winding the tape in an overlapping manner resulting in a stepped outer surface facing towards the outer cladding, and wherein the outer cladding comprises a metal, such as is made from metal.

2-13. (canceled)

14. The method according to claim 1, wherein the outer cladding is in direct contact with the endothermic material.

15. The method according to claim 1, wherein an overlap between subsequent windings of the tape is 20 to 80% of a width of the tape.

16. The method according to claim 1, wherein more than one layer of the endothermic material is applied.

17. The method according to claim 1, wherein the outer cladding is made from steel.

18. The method according to claim 1, wherein the outer cladding is dimensioned and shaped so that the outer diameter thereof remains substantially the same before and after the outer cladding has been exposed to temperatures above 1,100 C.

19. The method according to claim 1, wherein the endothermic material is a rubber-based or a polymer-based material.

20. The method according to claim 1, wherein the endothermic material is a material, which will, at a first elevated temperature, undergo a first endothermic process during which water is released and evaporated and, at a second elevated temperature higher than the first elevated temperature, undergo a second endothermic process during which a physically and thermally stable fire barrier is created.

21. The method according to claim 1, wherein the endothermic material comprises an inorganic filler in a binder.

22. The method according to claim 1, wherein the object has been installed before the endothermic material and the outer cladding are arranged thereon.

23. A fire protective covering for an object, the covering comprising: an endothermic material provided as a tape and configured to be helically wound around the object in an overlapping manner resulting in a stepped outer surface facing towards an outer cladding, wherein the outer cladding is configured so that it covers at least a part of the endothermic material, and wherein the outer cladding comprises a metal.

24. The fire protective covering according claim 23, wherein the outer cladding is made from steel.

25. The fire protective covering according to claim 23, wherein the outer cladding is dimensioned and shaped so that the outer diameter thereof remains substantially the same before and after the outer cladding has been exposed to temperatures above 1,100 C.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] The method of protecting an object against fire according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0039] FIG. 1 schematically shows an object to be protected against fire, the object having an endothermic material helically wound around it.

[0040] FIG. 2 schematically and in partial view shows how the helical winding of the tape of endothermic material results in air cavities being formed underneath the outer cladding.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0041] FIG. 1 schematically shows how an object 1 can be protected against fire by use of a method according to the present invention. The illustrated object 1 is in the form of a pipe, but the method can be used in relation to any geometry which is adapted to receive the wound material. The method comprises arranging an endothermic material 2 in the form of a tape 3 around the object 1 so that it covers at least a part of the object 1. In the embodiment in FIG. 1, the object 1 has two layers helically wound around it. The overlap between subsequent windings of the tape 3 is typically between 20 to 80% of a width of the tape, such as 25 to 50%. However, any amount of overlap is covered by the scope of the present invention. The outermost of the layers is an endothermic material. The innermost layer 4 may also be an endothermic material, such as the same in the outermost layer 3, but it may also be another material providing other types of protection to the object 1, such as thermal insulation or moisture protection. It can e.g. be a fibre-based material with fibres made from stone wool, Alcali Earth Silicates, or glass fibre impregnated aerogels. An outer cladding 5 is arranged to cover at least a part of the endothermic material 2. In FIG. 1, the outer cladding 5 covers only a small part of the endothermic material 2, but that is for illustrative purposes only; i.e. to more clearly illustrate the endothermic material. In a real use, the outer cladding 5 would typically cover all or most of the endothermic material 2.

[0042] As shown in FIG. 1, the endothermic material is provided as a tape 3 which is applied by helically winding the tape 3 in an overlapping manner resulting in a stepped outer surface 6 facing towards the outer cladding 5.

[0043] FIG. 2 schematically shows a part of the embodiment in FIG. 1. The figure illustrates how the helical winding of the tape 3 of endothermic material results in air cavities 7 being formed underneath the outer cladding 5 at the edges 8 of the tape 3. Preferably, the outer cladding 5 is arranged in direct contact with the endothermic material so that an efficient cooling of the outer cladding 5 can be ensured.

[0044] As explained above, such an arrangement means that when the object 1 is exposed to a fire, and the thermal load of the fire hits the outer cladding 5, such small air cavities 7 will allow for a slight swelling of the endothermic material 2 that will, as a consequence of the fire, absorb some of the heat and initiate an endothermic reaction. This particular reaction process will therefore prolong the time until failure and consequently breach of the outer cladding 5 itself.

[0045] The outer cladding 5 is typically made from a metal, such as steel. An example of a steel typically used for fire protective claddings is AISI 316 SS. However, other materials are also covered by the scope of protection.

[0046] The endothermic material 2 is preferably a rubber-based or a polymer-based material. In some embodiments of the invention, the endothermic material 2 is a material which will, at a first elevated temperature, undergo a first endothermic process during which water is released and evaporated and, at a second elevated temperature higher than the first elevated temperature, undergo a second endothermic process during which a physically and thermally stable fire barrier is created. Such a first endothermic process will cool down the outer cladding 5 from underneath and consequently prolong the time to failure. Such a second endothermic process typically results in the formation of a physically and thermally stable substance forming a fire barrier and will also, to some extent, cool off the outer cladding prolonging the time to failure. The resulting thermally stable substance may have a low thermal conductivity, and as a result, will delay the heat penetration considerably in time, and yield further protection against damage of the object 1.

[0047] An example of an endothermic polymer-based material which can be used in relation to the present invention is the product FAVUSEAL NKX-6174 available from Favuseal AS, Norway. FAVUSEAL NKX-6174 is a thermoplastic material containing inorganic fillers in a binder composed of an ethylene copolymer. It may e.g. be an ethylene vinyl acetate (EVA) based material which is highly filled with Alumina Tri-hydrate, which will lead to a very strong endothermic reaction process when exposed to temperatures in excess of 180 C. The second endothermic reaction process starts at 700-800 C. where a micro-porous steady state ceramic will be generated. This particular micro-porous state will have a very low thermal conductivity coefficient when, for instance, the invention is exposed to a standard 250 kW/m.sup.2 jet fire. The thermal conductivity coefficient has been identified by numerous jet fire tests conducted to be at 0.05 (W/m/K) at 1,000 C. and 0.04 at 1,300 C. for various jet fire scenarios.

[0048] During exposure to flame or heat, FAVUSEAL NKX-6174 goes through the following stages of transformation: [0049] 90 C. Softening [0050] 200 C. Evolution of water, swelling [0051] 300 C. Pyrolysis of the polymeric binders [0052] 800 C. Formation of rigid cellular ceramics stable up to 1,500 C.

[0053] When FAVUSEAL NKX-6174 is subjected to heat, for example in a fire, two phase transitions take place. The first phase transition takes place between 200 and 250 C. and the second phase transition takes place between 700 and 800 C. At the first phase transition, crystal water is generated from the OH groups in the fillers. The water evaporates and the reaction is strongly endothermic, i.e. heat absorbing. The temperature behind the barrier of FAVUSEAL NKX-6174 will not exceed approximately 300 C. as long as this reaction takes place because this process actually consumes energy which is used to release the water. The second phase transition is at 700-800 C. creating a solid micro-porous ceramic substance with extreme very low thermal conductivity which also is physically stable.

[0054] The method according to the present invention may be used to add fire protection properties to an object 1 which has already been installed before the endothermic material 2 and the outer cladding 5 is arranged thereon. Alternatively, the fire protection may be applied as part of the initial installation process.

[0055] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms comprising or comprises do not exclude other possible elements or steps. In addition, the mentioning of references such as a or an etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.