OA19906A - Method of protecting an object against fire and fire protective covering for an object. - Google Patents

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 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.

Description

METHOD OF PROTECTING AN OBJECT AGAINST PIRE

FIELD OF THE INVENTION

The présent invention relates to a method of protecting an object against fire. In particular, it relates to a method by which it is possible to prolong the time for which an outer cladding covering the object remains intact in case of exposure to fire, such as hydrocarbon fire or jet fire. The invention also relates to a method by which the outer dimension of the outer cladding remains substantially unchanged before and after being exposed to fire.

BACKGROUND OF THE INVENTION

Passive fire protection is used to protect objects against fire to retard the spreading of the fire and avoid loss of integrity of the object being protected. In general, such objects include electric cables, pipes and tanks conducting or containing hydrocarbons or other flammable materials, ventilation ducts, safety deposit boxes, pénétration seals for cables and pipes in walls etc. Heat sources causing hazardous risks to an object include cellulosic fire, hydrocarbon fire, jet fire, hot gases, infrared radiated heat etc. According to ISO 834-3, hydrocarbon fire results in heat exposure up to 200 kW/m², and jet fire results in heat exposure exceeding 200 kW/m².

Known passive fire protection methods comprise the use of structural components, such as fire-resistant walls, floors, and doors. It may also be in the form of e.g. an insulating layer of minerai fibres which will delay the heat from the fire in reaching the protected object on the cold side of the insulating layer. Other known technologies use intumescent materials which upon heating will expand and increase in volume. An example of such a type of material is known from CN201812530 U.

Still other technologies use materials which upon heating will go through one or more phases in which the material will react chemically and/or physically with one or more endothermie reactions, e.g. where hydrates are spent and water vapour is released, which has a cooling effect. Materials with such endothermie properties include polymer-based materials and rubber-based materials which can be applied to the surface of the object to be protected.

For some applications, fire protection of an object is provided in the form of the mentioned fire protection technologies, but with a metal-based outer cladding providing mechanical integrity to the technology used for the passive fire protection. Such a metal-based cladding also provides mechanical protection e.g. against wear and tear, and influence from the weather, and it removes any érosion issues related especially to any jet fire curves. However, at high températures in case of fire, and in particular hydrocarbon fire and jet fire, there is a risk that the métal cladding will erode and melt away resulting in failure of the adopted fire protection technology.

Oil installations around the world are becoming more and more complex. Consequently, more equipment is placed on them and they are now very condensed and may e.g. hâve several pipes arranged adjacent to each other. If such pipes are fire protected with an intumescent paint based System, the intumescent paint will be designed to expand by upto 500-900% from its original State in case of exposure to fire. This expansion is required for the paint to build up a thermal barrier against the heat and, consequently, delay the time it takes for the heat to penetrate the reacted paint. If such expansion is interrupted, e.g. due to iack of free space, the technology does not work as intended and it will fail in providing the desired protection.

Hence, an improved method of protecting an object against fire would be advantageous, and in particular a more efficient and/or reliable method would be advantageous.

OBJECT OF THE INVENTION

It is an object of the présent invention to provide a method of protecting an object against fire which results in a longer time to failure of an outer cladding covering the object for a given fire scénario.

It is another object of the présent invention to provide a method of protecting an object against fire that can be applied to an already installed object.

It is an object of at least some embodiments of the invention to provide a method of protecting an object against fire with which the outer diameter of an outer cladding remains substantially the same before and after being exposed to fire.

It is a further object of the présent invention to provide an alternative to the prior art.

In particular, it may be seen as an object of the présent invention to provide a method of protecting an object against fire that solves the above mentioned problems of the prior art.

SUMMARY OF THE INVENTION

Thus, the above-described object and several other objects are intended to be obtained in a first aspect of the invention by providing a method of protecting an object against fire, the method comprising:

arranging an endothermie 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 endothermie material, wherein the endothermie material is 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 meta!, such as is made from métal.

By endothermie material is preferably meant a material which when subjected to heat undergoes a phase-changing State incorporating one or more endothermie reaction processes. As this is an energy-demanding reaction, some of the heat from the fire will be consumed by the endothermie process and thereby delay the increase in température of the object to be protected. More importantly, it will also increase the time to failure of the outer cladding covering the endothermie material, as it will, in effect, cool down the cladding from the inside and consequently prolong the time to failure of the outer cladding.

By tape is preferably meant in the form of a band having a width and being long 5 enough to be wound several times around the object. The spécifie length for a given application dépends on the size of the object to be protected and the amount of overlap between subséquent windings. The term a band does not exclude that the endothermie material can be in the form of successively arranged separate tapes of material.

The stepped outer surface results in air cavities being formed underneath the outer cladding; this will be shown in relation to the figures. When the object is exposed to a fire and the thermal ioad of the fire hits the outer cladding, such small air cavities will allow for a slight swelling of the endothermie material that 15 will, as a conséquence of the fire, react and release water directly to the outer cladding from underneath. As mentioned, this particular reaction process will cool down the outer cladding from underneath and prolong the time until failure and consequently breach of the cladding itself. Thus, arranging the components of the fire protection as described above will inherently increase the integrity of the 20 outer cladding by preventing or delaying e.g. métal melt down, or deformation of the outer cladding itself.

In presently preferred embodiments of the invention, the outer cladding is arranged in direct contact with the endothermie material. Hereby the cooling 25 effect of the endothermie material can be directly applied to the outer cladding so that the cooling is as efficient as possible. Due to the stepped outer surface of the endothermie material, the direct contact will be where the diameter of the wound endothermie material is largest; this will be shown in the figures. Alternatively, a layer of intermediate material may be arranged between the endothermie material 30 and the outer cladding to provide further protection. Such a material may e.g. be used to provide protection against moisture. However, such an intermediate layer should not limit the cooling effect by any significant amount.

An overlap between subséquent windings of the tape of endothermie material may 35 be 20 to 80% of a width of the tape, such as 25 to 50%.

In some embodiments of the invention, more than one layer of the endothermie material is applied. This may e.g. be necessary to fulfil the requirements in a given fire class.

The outer cladding may be made Steel. An example of a Steel typicaliy used for fire protective claddings is AISI 316 SS. Such a métal cladding has been found useful in relation to hydrocarbon fire scénarios (1,100 °C) or jet fire scénarios (1,200 - 1,500 °C). Thus, the outer cladding may be dimensioned and shaped so that the outer diameter thereof remains substantially the same before and after the outer cladding has been exposed to températures above l,100°C, such as températures between 1,200 and l,500°C. Keeping the outer dimension constant in a fire is regarded advantageous as land-terminals, oil rigs, Floating Production Storage and Offloading vessels, and Floating Liquified Naturel Gas vessels are becoming more complex and condensed with respect to e.g. pipework. Traditionally used expandable fire protection technologies require free space in order to work as they might expand by upto 500-900% from their Virgin State. As described above, if such an expandable technology is not allowed to fully expand freely, it will loose its inhérent fire protection properties, and the technology will not work as intended. Therefore, with traditionally used fire protection technologies based on expanding materials, it is very important to make sure that the material is free to expand. However, there is not always room for this. It is therefore an advantage of the présent invention that with such a method, the outer dimension of the outer cladding remains substantially unchanged before and after being exposed to fire.

Exampies of other materials which may also be used for the outer cladding are aluminium covering, silica tape reinforced with Steel wiring, Zink-based covering, stainless Steel métal covering, and glass fibre reinforced poiymer (GRP) covering reinforced with Steel wiring.

The endothermie material may be a rubber-based or a polymer-based material. In some embodiments of the invention, the endothermie material may be a material which will, at a first elevated température, undergo a first endothermie process during which water is released and evaporated and, at a second elevated température higher than the first elevated température, undergo a second endothermie process during which a physically and thermally stable fire barrier is created. An example of such a material will be presented in the detailed description.

The endothermie material may contain inorganic fiilers in a binder. It may e.g. be a thermoplastic material composed of a co-polymer, such as an ethylene copolymer. Such a technology has proven to be robust to weathering conditions over time and fluctuations in température.

In some embodiments of the invention, the object to be protected has already been installed before the endothermie material and the outer cladding are arranged thereon. Thus, the method can be used to up-grade the fire résistance of an object and thereby possibly of a whole installation of which it forms part.

In a second aspect, the présent invention relates to a fire protective covering for an object, the covering comprising:

- an endothermie material provided as a tape and adapted to be helically wound around the object in an overlapping manner resulting in a stepped 20 outer surface facing towards an outer cladding, and

- the outer cladding adapted to be arranged so that it covers at least a part of the endothermie material, and wherein the outer cladding comprises métal, such as is made from métal.

The outer cladding may made from Steel, such as AISI 316 SS.

The outer cladding may dimensioned and shaped so that the outer diameter thereof remains substantially the same before and after the outer cladding has been exposed to températures above l,100°C, such as températures between

1,200 to l,500°C.

The first and second aspects of the présent invention may each be combined with any of the other aspects. This means that the features now described in relation to the first aspect is also possible features of the second aspect of the invention.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

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 présent invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

Figure 1 schematically shows an object to be protected against fire, the object having an endothermie m.aterial helically wound around it.

Figure 2 schematically and in partial view shows how the helical winding of the tape of endothermie material results in air cavities being formed underneath the outer cladding.

DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 schematically shows how an object 1 can be protected against fire by use of a method according to the présent invention. The iiiustrated 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 endothermie 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 figure 1, the object 1 has two layers helically wound around it. The overlap between subséquent 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 présent invention. The outermost of the layers is an endothermie material. The innermost layer 4 may also be an endothermie 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 endothermie material 2. In figure 1, the outer cladding 5 covers only a small part of the endothermie material 2, but that is for illustrative purposes only; i.e. to more clearly illustrate the endothermie material. In a real use, the outer cladding 5 would typically cover ail or most of the endothermie 5 material 2.

As shown in figure 1, the endothermie 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.

Figure 2 schematically shows a part of the embodiment in figure 1. The figure illustrâtes how the heiicai winding of the tape 3 of endothermie material results in air cavities 7 being formed underneath the outer cladding 5 at the edges 8 of the tape 3. Preferabiy, the outer cladding 5 is arranged in direct contact with the 15 endothermie material so that an efficient cooling of the outer cladding 5 can be ensured.

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 20 small air cavities 7 will aliow for a slight swelling of the endothermie material 2 that will, as a conséquence of the fire, absorb some of the heat and initiate an endothermie reaction. This particular reaction process will therefore prolong the time until failure and consequently breach of the outer cladding 5 itself.

The outer cladding 5 is typically made from a métal, 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.

The endothermie material 2 is preferabiy a rubber-based or a polymer-based 30 material. In some embodiments of the invention, the endothermie material 2 is a material which will, at a first elevated température, undergo a first endothermie process during which water is released and evaporated and, at a second elevated température higher than the first elevated température, undergo a second endothermie process during which a physically and thermally stable fire barrier is 35 created. Such a first endothermie process will cool down the outer cladding 5 from underneath and consequently prolong the time to failure. Such a second endothermie 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 hâve a low thermal conductivity, and as a resuit, will delay the heat pénétration considerably in time, and yield further protection against damage of the object 1.

An example of an endothermie polymer-based material which can be used in relation to the présent invention is the product FAVUSEAL® NKX-6174 available from Favuseal AS, Norway. F.AVUSEAL® NKX-6174 is a thermoplastic material containing inorganic fiilers 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 endothermie reaction process when exposed to températures in excess of 180 °C. The second endothermie reaction process starts at 700-800 °C where a micro-porous steady State ceramic will be generated. This particular micro-porous State will hâve a very low thermal conductivity coefficient when, for instance, the invention is exposed to a standard 250 kW/m² 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 scénarios.

During exposure to flame or heat, FAVUSEAL® NKX-6174 goes through the following stages of transformation:

· 90 °C Softening • 200 °C Evolution of water, swelling « 300 °C Pyrolysis of the polymeric binders • 800 °C Formation of rigid cellular ceramics stable up to 1,500 °C

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 O-H groups in the fiilers. The water evaporates and the reaction is strongly endothermie, i.e. heat absorbing. The température 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.

Tne method according to the présent invention may be used to add fire protection properties to an object 1 which has already been installed before the endothermie materiai 2 and the outer cladding 5 is arranged thereon. Alternatively, the fire protection may be applied as part of the initial installation process.

Although the présent 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 présent invention is set out by the accompanying claim set. In the context of the daims, the terms comprising or 15 comprises do not exclude other possible éléments 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 daims with respect to éléments indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different daims, 20 may possibly be advantageously combined, and the mentioning of these features in different daims does not exclude that a combination of features is not possible and advantageous.

The invention is not limited to the embodiment/s illustrated in the drawings. 25 Accordingly it should be understood that where features mentioned in the appended daims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the daims and are in no way limiting on the scope of the daims.

Claims (15)

1. Method of protecting an object (1) against fire, the method comprising: arranging an endothermie materiai (2) around the object (1) so that it

5 covers at least a part of the object (1), and

- arranging an outer cladding (5) covering at least a part of the endothermie materiai (2), wherein the endothermie materiai (2) is provided as a tape (3) which is applied by helically winding the tape (3) in an overlapping manner resulting in a stepped

10 outer surface (6) facing towards the outer cladding (5), and wherein the outer cladding (5) comprises métal.

2. Method according to claim 1, wherein the outer cladding is made from métal.

15

3. Method according to claim 1 or 2, wherein the outer cladding (5) is arranged in direct contact with the endothermie materiai (2).

4. Method according to any one of the preceding daims, wherein an overlap between subséquent windings of the tape (3) is 20 to 80% of a width of the tape.

5. Method according to any of the preceding daims, wherein more than one layer (3, 4) of the endothermie materiai (2) is applied.

6. Method according to any of the preceding daims, wherein the outer cladding

25 (5) is made from Steel.

7. Method according to any of the preceding daims, 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 températures

30 above l,100°C.

8. Method according to any of the preceding daims, wherein the endothermie materiai (2) is a rubber-based or a poiymer-based materiai.

9. Method according to any of the preceding claims, wherein the endothermie material (2) is a material which will, at a first elevated température, undergo a first endothermie process during which water is released and evaporated and, at a second elevated température higher than the first elevated température, undergo

5 a second endothermie process during which a physically and thermally stable fire barrier is created.

10. Method according to any of the preceding claims, wherein the endothermie material (2) contains inorganic fillers in a binder.

11. Method according to any of the preceding claims, wherein the object (1) has already been installed before the endothermie material (2) and the outer cladding (5) are arranged thereon.

15

12. Fire protective covering for an object (1), the covering comprising:

an endothermie material (2) provided as a tape (3) and adapted to be helically wound around the object (1) in an overlapping manner resulting in a stepped outer surface (6) facing towards an outer cladding (5), and

- the outer cladding (5) adapted to be arranged so that it covers at least a

20 part of the endothermie material (2), and wherein the outer cladding (5) comprises métal.

13. Fire protective covering according to claim 12, wherein the outer cladding is made from métal.

14. Fire protective covering according claim 12 or 13, wherein the outer cladding (5) is made from Steel.

15. Fire protective covering according to any one of claims 12 to 14, wherein the 30 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 températures above l,100°C.