EP2694164B1 - Protective fire-resistant coating and application method - Google Patents

Description

The present invention relates to techniques for protecting installations against fire.

A distinction is made between active protection techniques, in which detectors are used to detect fire conditions in order to trigger a response by active elements, and passive protection techniques to which the present invention relates more particularly.

Fire-resistant coatings are used to implement passive protection techniques. A remarkable coating was the subject of the patent EP 0 612 540 . It is a flexible coating comprising a complex of fibrous and / or textile elements, in particular based on mineral wool, assembled by gluing. The glue used is an active refractory glue having a temperature resistance up to about 1300 ° C and incorporating active components or additives containing chemically bound water, and stable at temperatures below about 80 ° C. Aluminosilicates are typically used in glues of this type.

Another coating of the prior art is known from the document US 2008/0166937 A , it relates to a laminate comprising several layers of material bonded to each other by refractory glue comprising active elements capable of releasing water during a rise in temperature, one of the layers of glue also incorporating a layer vapor permeable backing.

The passive coating retards the propagation of heat between a hot side, through which it is susceptible to being reached by an accidental fire, and a cold side towards the protected installation. The delay effect is largely due to the release of water molecules from the glue when the temperature rises. Water absorbs heat as it vaporizes, resulting in a plateau at 100 ° C in the temperature increase curve of the cold side as a function of time.

• densifier la colle. Mais celle-ci risque alors de devenir trop épaisse et très difficile à mettre en œuvre pour l'application d'un revêtement souple. Cette difficulté est encore accrue par le temps de séchage réduit résultant de l'épaississement de la colle. En outre, la colle trop dense peut endommager la laine minérale lorsqu'elle est étalée;
• augmenter la quantité de colle entre deux couches fibreuses. Dans ce cas, la colle tend à couler lorsqu'elle est appliquée et avant séchage. Cette solution ne permet pas de garantir une bonne répartition spatiale de la protection anti-feu;
• augmenter le nombre de couches de laine minérale et de colle entre elles. L'inconvénient est alors de voir augmenter notablement l'encombrement du revêtement.

Naturally, it is desirable to increase the duration of this plateau at 100 ° C. by increasing the quantity of adhesive incorporated in the passive coating. Several methods are possible for this purpose:

• densify the glue. But this then risks becoming too thick and very difficult to implement for the application of a flexible coating. This difficulty is further increased by the reduced drying time resulting from the thickening of the glue. In addition, glue that is too dense can damage the mineral wool when it is spread;
• increase the amount of glue between two fibrous layers. In this case, the glue tends to flow when applied and before drying. This solution does not make it possible to guarantee a good spatial distribution of the fire protection;
• increase the number of layers of mineral wool and glue between them. The disadvantage is then to see a marked increase in the size of the coating.

An important, although not exclusive, field of application of passive coatings of this type is in the fire protection of industrial installations requiring a high level of safety. In particular, they are commonly used to protect cable trays or other electrical equipment in nuclear power plants. In view of the ever-increasing safety requirements, in particular in these plants, there is a need to improve the performance of fire-resistant coatings.

Due to the increasing level of safety, there is more and more redundancy in electrical equipment, in particular in cables. Up to four levels of redundancy can be seen in the cable trains, instead of just two levels in earlier generations of power plants. It is therefore necessary to protect a greater number of cable trays, which can make solutions where the coating is too bulky unacceptable. Rather, it would be desirable for the best performance of the coating to be obtained while being accompanied by greater compactness thereof.

One aim of the invention is to meet at least some of the needs set out above.

• plusieurs couches fibreuses superposées; et
• au moins une couche de colle réfractaire placée entre deux des couches fibreuses, la colle comprenant des éléments actifs capables de libérer de l'eau lors d'une élévation de température; et
• dans au moins une couche de colle réfractaire, un support perméable à la vapeur s'étendant parallèlement aux couches fibreuses et imprégné par la colle réfractaire.

A fire protection coating is offered, comprising:

• several superimposed fibrous layers; and
• at least one layer of refractory adhesive placed between two of the fibrous layers, the adhesive comprising active elements capable of releasing water during a rise in temperature; and
• in at least one layer of refractory glue, a vapor-permeable support extending parallel to the fibrous layers and impregnated with the refractory glue.

The vapor-permeable backing retains the refractory glue by preventing it from flowing during the application phase. In the event of a fire, it does not disturb the diffusion of the vaporized water, which improves the effectiveness of the coating by achieving better penetration into the fibrous layers regardless of their density.

It is then conceivable to increase the density of the fibrous layers, in particular by making it greater than 140 kg / m ³ . A preferred density value is substantially 150 kg / m ³ .

These fibrous layers made more dense can have reduced thickness, down to values of less than 30 mm, the thicknesses commonly used up to now being rather of the order of 38 mm. These arrangements advantageously make it possible to reduce the size of the fire protection coating without sacrificing the performance thereof.

The vapor-permeable backing promotes adhesive impregnation which prevents damage to the fibrous layers. It is preferably made of an incombustible material (Euroclass A1), which may include a web of refractory fibers, typically a glass cloth.

• disposer une première couche fibreuse, éventuellement encollée de colle réfractaire, sur un élément à protéger;
• appliquer une couche de colle réfractaire sur la première couche fibreuse, la couche de colle réfractaire comprenant des éléments actifs capables de libérer de l'eau lors d'une élévation de température et incorporant un support perméable à la vapeur s'étendant parallèlement à la première couche fibreuse et imprégné par la colle réfractaire; et
• disposer au moins une deuxième couche fibreuse par-dessus la couche de colle réfractaire.

Another aspect of the present invention relates to a method of applying a fire protection coating, comprising the following steps:

• placing a first fibrous layer, optionally glued with refractory adhesive, on an element to be protected;
• applying a layer of refractory glue on the first fibrous layer, the layer of refractory glue comprising active elements capable of releasing water upon a rise in temperature and incorporating a vapor-permeable support extending parallel to the first fibrous layer and impregnated with refractory glue; and
• have at least a second fibrous layer over the refractory adhesive layer.

In a convenient implementation, the vapor permeable backing is glued to the first fibrous layer before placing the first fibrous layer on the element to be protected. The support then contributes to the cohesion of the first fibrous layer when the latter is placed on the element to be protected. This reduces the risk of the fibrous layer tearing, especially in areas where it must follow a relatively strong curvature.

Other features and advantages of the present invention will emerge from the following description of a non-limiting example embodiment, with reference to the appended drawing comprising a single figure which shows a cross section of a fire protection coating according to one embodiment of the invention.

In the embodiment shown in the figure, the fire protection coating comprises two superimposed fibrous layers 1, 2, made from needled mineral wool or other suitable fibrous refractory material. In a manner known per se, the fibrous layers 1, 2 may optionally contain, in their thickness, particles which help to slow down the propagation of heat.

These fibrous layers 1, 2 cover an element 3 to be protected against the risk of fire, such as, for example, a cable or pipe tray, an electrical cabinet or cabinet, control or transmission members, etc.

A refractory glue is incorporated into the fire-resistant coating, in particular in the form of a layer 4 placed between the two fibrous layers 1, 2. As is customary in this type of coating, the glue used comprises active elements which release water when the temperature rises, for example above 80 ° C. By vaporizing at 100 ° C, this water slows down the propagation of heat from the exterior (hot) side of the coating to its interior (cold) side. One can in particular use an adhesive called F.active, based on hydrates of metal oxides.

In the refractory glue layer 4 there is a two-dimensional vapor-permeable backing 5. A suitable material for this backing 5 is a glass fiber cloth since such a cloth is relatively inexpensive while having the desired properties, in particular a good capacity to be impregnated by the refractory adhesive and a good capacity to diffuse the water vapor released when the temperature of the coating rises. It is also an incombustible material (Euroclass A1), which therefore does not contribute to the fire in the event of a fire.

The fabric 5 impregnates and retains the refractory adhesive during its application, which ensures a satisfactory distribution of the adhesive over the extent of the coating. It thus makes it possible to increase the quantity of adhesive placed between the fibrous layers 1, 2, and therefore to improve the performance of the fire-resistant coating.

The vapor-permeable support 5 tends to avoid inhomogeneities in the distribution of the refractory glue, in particular where the layer 4 extends vertically. This function is performed during the installation of the coating, but also subsequently once the adhesive has set, the coating being able to be subjected to vibrations.

Conventionally, the fire-resistant coating may include on its external face a casing 6 ensuring its tightness. This envelope 6 is for example made from a fabric of mineral fibers impregnated with a fire-retardant elastomer.

For the installation of the fire-resistant coating on an element to be protected 3, one can for example proceed as follows.

First, the first fibrous layer 1 is spread on the floor or another work surface, and F.active glue is applied to its outer face, then the glass cloth 5 which is left to impregnate with the glue.

Element 3 is glued with F.active glue or another suitable glue 7, then the first fibrous layer 1 is placed therein.

After the installation of this first fibrous layer 1, we spread again F. active glue on its outer face to complete layer 4, then the second fibrous layer 2 is placed on top of the refractory glue layer 4. If necessary, ropes can be put in place around the fibrous layer to maintain the assembly.

Finally, the sealing envelope 6 is glued to the second fibrous layer 2 using an appropriate adhesive 8.

If it is necessary to provide more than two fibrous layers 1, 2, the layers can be placed successively with, for each layer except the last, a glass fabric 5 pre-glued on its external face.

It is also possible to place the glass cloth 5 on the fibrous layer 1 after gluing the latter on the element to be protected 3. However, it is preferable to apply the cloth 5 to the fibrous layer 1 beforehand. the installation thereof, because the risk of tearing the fibrous layer 1 is then reduced by virtue of the pre-glued fabric.

Another aspect of the invention, which the presence of the vapor-permeable support 5 makes it possible to promote, relates to an increase in the density of the fibrous layers 1, 2. This density can in particular exceed the value of 140 kg / m ³ . The density value is for example 160 kg / m ³ or, in an interesting compromise, about 150 kg / m ³ .

By thus increasing the density of the mineral wool used, it is possible to reduce the thickness of the layers 1, 2 with comparable performance, and therefore to limit the size of the coating.

In particular, the thickness of the fibrous layers 1, 2 can be made less than 30 mm. A possible value for this thickness is 25 mm. If we compare the use of fibrous layers 1, 2 with a density of 150 kg / m ³ and a thickness of 25 mm with that of conventional layers with a density of 125 kg / m ³ and a thickness of 38 mm, we see that the thickness of each layer is reduced by 34.2%, while the overall weight of mineral wool in the fireproof coating and reduced by 21.1%. The dimensioning envisaged is also advantageous in terms of weight, which is of course desirable, including from the point of view of requirements to be met in the event of an earthquake.

The embodiments described or mentioned above are illustrations of the present invention. Various modifications can be made to them without departing from the scope of the invention which emerges from the appended claims.

Claims (11)

1. Protective fire-resistant coating, comprising:

   - a plurality of stacked fibrous layers (1, 2); and

   - at least one refractory glue layer (4) placed between two of the fibrous layers, the glue comprising active elements capable of releasing water upon a temperature increase;

   characterized in that in at least one refractory glue layer, a vapor-permeable support (5) extends parallel to the fibrous layers and is impregnated with the refractory glue.
2. Protective fire-resistant coating according to claim 1, wherein the vapor-permeable support (5) is of non-combustible material.
3. Protective fire-resistant coating according to claim 2, wherein the vapor-permeable support (5) comprises a cloth of refractory fibers.
4. Protective fire-resistant coating according to claim 3, wherein the cloth of refractory fibers (5) is a fiberglass cloth.
5. Protective fire-resistant coating according to any one of the preceding claims, wherein at least some of the fibrous layers (1, 2) have a density greater than 140 kg/m³
6. Protective fire-resistant coating according to claim 5, wherein the density of said fibrous layers (1, 2) is substantially 150 kg/m³.
7. Protective fire-resistant coating according to claim 5 or 6, wherein the fibrous layers (1, 2) of a density greater than 140 kg/m³ have a thickness of less than 30 mm.
8. Method for forming a protective fire-resistant coating, comprising:

   - placing a first fibrous layer (1) onto an element to be protected (3);

   - applying the refractory glue layer (4) onto the first fibrous layer, the refractory glue layer comprising active elements capable of releasing water upon a temperature increase and incorporating the vapor-permeable support (5) extending parallel to the first fibrous layer and impregnated with the refractory glue; and

   - placing at least a second fibrous layer (2) over the refractory glue layer.
9. Method according to claim 8, wherein the vapor-permeable support (5) is glued onto the first fibrous layer (1) before the first fibrous layer is placed onto the element to be protected (3).
10. Method according to claim 8 or 9, wherein the vapor-permeable support (5) comprises a fiberglass cloth.
11. Method according to any one of claims 8 to 10, wherein the first and second fibrous layers (1, 2) each have a density greater than 140 kg/m³ and a thickness of less than 30 mm.

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