Method for repairing existing insulation material

Abstract

To provide a method for repairing existing insulation material that reduces the effort and time required through simple repair work and prevents increases in material costs.SOLUTION: The repair portion is cut out in a stepped manner so that the notch width decreases from the outer periphery side, which is the ignition side when viewed in cross section, to the inner periphery side. The fire-resistant wrapping material includes a first insulation layer provided on the outermost periphery of the repair portion and which reduces heat transferred from the ignition source to a first temperature range; a second insulation layer provided on the inner periphery side of the first insulation layer and which reduces heat transferred from the first insulation layer to a second temperature range; a heat absorption layer provided on the inner periphery side of the second insulation layer and formed from a heat absorption material that maintains heat in the second temperature range at the second temperature range based on an endothermic reaction; and an inner periphery insulation layer provided on the inner periphery side of the heat absorption layer to which heat is transferred, which is formed from the same material as the second insulation layer and has a fire-resistant protection object provided on its inner periphery side. The step portion at the inner periphery end of the heat absorption layer is provided in a state where it is covered from the inner periphery side by the existing insulation material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for repairing existing insulation. [Background technology]

[0002] In nuclear power plants, the fire protection inspection standards stipulate that cables of equipment related to hot shutdown or cold shutdown of the reactor between different safety zones must be separated by partitions or other devices with a fire resistance capacity of at least three hours. For this reason, the conduits and cable trays in which the cables are stored are wrapped and covered with insulating and heat absorbing materials, and fire-resistant wrapping is applied to prevent the loss of necessary electrical properties in the event of a fire (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-171176 A Summary of the Invention [Problem to be solved by the invention]

[0004] The fire-resistant wrapping material is required to have fire resistance performance that maintains the protected object for a certain period of time until the fire is extinguished in the event of a fire outside the cable facility. Furthermore, when partial repairs or replacement are required after the fire-resistant wrapping material is installed, if it is difficult to procure the same materials as the existing fire-resistant wrapping material due to a production stoppage of the existing fire-resistant wrapping material, it is necessary to remove the existing fire-resistant wrapping material and replace it with a new fire-resistant wrapping material. Therefore, the construction requires time and effort, and the cost of the materials increases, so there is room for improvement in this regard.

[0005] The present invention aims to provide a method for repairing existing insulation material, which can reduce the labor and time required for repair work by a simple method and also suppresses an increase in the cost of materials. [Means for solving the problem]

[0006] One aspect of the present invention is a method for repairing existing insulation formed in layers on a fire-resistant protection object, the method comprising the steps of cutting out the existing insulation of the object to be repaired to form a repair section, and installing a new fire-resistant repair wrapping material on the repair section, the repair section being cut out in a stepped manner such that the notch width becomes smaller from the outer periphery side, which is the ignition side when viewed in cross section, toward the inner periphery side, the repair fire-resistant wrapping material being provided on the outermost periphery of the repair section, the first insulation layer being made of a first insulation material having a first thermal conductivity that reduces heat transferred from an ignition source to a first temperature range, and a second insulation layer being provided on the inner periphery side of the first insulation layer, the second insulation layer being provided on the inner periphery side of the first insulation layer, A method for repairing existing insulation comprising: a second insulation layer made of a second insulation material having a second thermal conductivity that reduces heat transferred from a first insulation layer to a second temperature range; a heat absorption layer arranged on the inner side of the second insulation layer and formed from a heat absorption material that maintains heat in the second temperature range at the second temperature range based on an endothermic reaction; and an inner insulation layer arranged on the inner side of the heat absorption layer to which heat from the heat absorption layer is transferred, formed from the same material as the second insulation layer, and on whose inner side the fire-resistant protected object is arranged, wherein a step at the inner end of the heat absorption layer is arranged in a state where it is covered from the inner side by the existing insulation material.

[0007] According to the present invention, when an existing insulation needs to be partially repaired or replaced, the part that needs to be replaced is cut out in a stepped shape from the outer periphery of the ignition side toward the inner periphery so that the notch width becomes smaller, and a new fireproof wrapping material for repair made of a different material from the existing insulation is placed in the cut-out part, thereby repairing the existing insulation. In this way, the repair method for an existing insulation according to the present invention is a method of partially repairing an existing insulation by partially cutting out a part of the existing insulation, so that the labor and time can be reduced by a simple repair work, and the increase in the cost of the parts can be suppressed. In addition, in the present invention, the step part of the inner periphery end part of the heat absorption layer located in the center of the thickness direction of the repair fireproof wrapping material is arranged in a state covered from the inner periphery by the existing insulation material, so that the heat transfer from the heat absorption layer to the non-heated surface side can be suppressed, and the temperature rise can be reduced, and the fire resistance can be improved by repair using the fireproof wrapping material for repair. Furthermore, according to the present invention, since the first insulating layer having a first thermal conductivity lower than that of the second insulating layer is provided on the heating side of the second insulating layer, the second layer thickness of the second insulating layer can be made thinner than when the heating side is formed only with the second insulating layer so as to have the same level of fire resistance. Furthermore, according to the present invention, since the first layer thickness of the first insulating layer and the second layer thickness of the second insulating layer are formed so that the heat absorption layer has a heat absorption effect, fire resistance can be guaranteed.

[0008] In the present invention, the heat absorption layer may be formed in a plurality of steps, and each step may be covered from the inner periphery side by the existing heat insulating material.

[0009] According to the present invention, multiple steps are formed in the heat absorption layer, and each step is arranged so that it is covered from the inner periphery by existing insulation material, thereby more effectively suppressing heat transfer from the heat absorption layer to the non-heated surface side and reducing temperature rise.

[0010] In the present invention, the first and second insulating layers may be formed from the same material.

[0011] According to the present invention, by making the second insulation layer from the same material as the first insulation layer, the second layer thickness of the second insulation layer can be made thinner than when it is formed from the second insulation material.

[0012] The present invention may also be characterized in that the first layer thickness of the first insulation layer and the second layer thickness of the second insulation layer are adjusted so that the second insulation layer transfers heat in the second temperature range to the heat absorption layer within a predetermined fire resistance time after ignition, and uses up the heat absorption performance of the heat absorption layer.

[0013] According to the present invention, the heat absorbing layer uses up its heat absorbing effect during the fire resistance period, so that the excess heat absorbing material in the heat absorbing layer can be reduced, resulting in a reduction in weight.

[0014] In addition, in the present invention, the existing insulation material is wrapped circumferentially around the fire-resistant object to be protected, and the repair portion is formed around the entire circumference of the existing insulation material.

[0015] According to the present invention, a repair refractory wrapping material can be used to uniformly repair a repair portion in a circumferential direction, the repair portion being obtained by cutting out an existing insulation material all around the circumference.

[0016] In the present invention, the heat absorbing material of the heat absorbing layer may be formed of a powder material that separates water based on a chemical reaction when heated and exhibits an endothermic reaction.

[0017] According to the present invention, since the heat absorbing material does not normally contain moisture, performance degradation due to drying does not occur, and performance can be continuously maintained over time. Effect of the Invention

[0018] According to the method for repairing existing insulation material of the present invention, the repair work can be simplified, reducing the labor and time required, and also preventing an increase in the cost of materials. [Brief description of the drawings]

[0019] [Figure 1]FIG. 2 is a cross-sectional view showing a repair structure of a repair method for an existing insulation material according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross section taken along line II shown in FIG. 1, showing a longitudinal cross section of a repair structure for a repair method for an existing thermal insulation material. [Diagram 3] 1(a) to 1(c) are diagrams showing a construction procedure for a repair method for an existing thermal insulation material. [Figure 4] FIG. 2 is a diagram showing the configuration of a test specimen according to an embodiment. [Diagram 5] FIG. 1 is a diagram showing test results of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a method for repairing an existing insulation material according to an embodiment of the present invention will be described with reference to the drawings.

[0021] Facilities such as nuclear power plants are provided with cable equipment such as cables for power and communication, and cable trays for storing and supporting the cables. In the event of an external fire, the cable equipment is required to have fire-resistance measures to protect the cable equipment, which is the object of protection inside, from fire during a predetermined time (for example, about 3 hours) until fire-fighting work is carried out. This is also stipulated in, for example, the fire protection inspection standards for nuclear power plants. In addition, it is desirable for the fire-resistance measures to be lightweight in order to ensure the earthquake resistance of the cable equipment. The existing insulation material 2 of the embodiment shown in Figs. 1 and 2 has a lightweight configuration while ensuring fire resistance performance that protects the object of protection. The repair method of this embodiment is a method for repairing the existing existing insulation material 2 formed in layers on the fire-resistant protection object K.

[0022] As shown in Figures 1 and 2, the existing thermal insulation material 2 has a layered structure formed of multiple sheets. It is configured to lower the temperature based on the heat generated on the heated surface on the ignition side to a temperature that can protect the fire-resistant protection object K on the non-heated surface side. The fire-resistant protection object K is, for example, a cable facility.

[0023] Here, in the existing insulation material 2 and the fireproof wrapping material for repair 1 described later, the fireproof protection target K is the cable axis O. In a plan view seen from the direction of the cable axis O, the direction perpendicular to the cable axis O is defined as the radial direction, and the direction going around the cable axis O is defined as the circumferential direction. In addition, in the radial direction, the heating surface side is defined as the outer circumferential side, and the cable axis O side is defined as the inner circumferential side.

[0024] The existing insulation material 2 is, for example, arranged in multiple layers of the same sheet-shaped insulation material in the entire radial direction.

[0025] Next, the fireproof repair wrapping material 1 will be described with reference to FIGS. The repair fireproof wrapping material 1 is newly installed on the repair part 2A formed by cutting out the existing insulation material 2 to be repaired. The repair part 2A (see FIG. 3(b)) is cut out in a stepped shape so that the notch width (direction along the cable axis O) becomes smaller from the outer periphery, which is the ignition side, to the inner periphery in cross-sectional view.

[0026] The repair fireproof wrapping material 1 comprises, in order from the outer periphery side to the inner periphery side, an outer periphery insulating layer 3, a heat absorption layer 4, and an inner periphery insulating layer 5. The outer periphery insulating layer 3 and the inner periphery insulating layer 5 are each a sheet-like member.

[0027] The peripheral insulation layer 3 includes a first insulation layer 31 and a second insulation layer 32. The first insulation layer 31 is provided on the outermost periphery of the repaired portion 2A, and is made of a first insulation material with a first thermal conductivity that reduces heat transferred from an ignition source to a first temperature range. The second insulation layer 32 is adjacent to the inner surface 31a of the first insulation layer 31, and is made of a second insulation material with a second thermal conductivity higher than that of the first insulation material. The second insulation layer 32 is interposed between the first insulation layer 31 and the heat absorption layer 4.

[0028] The outer surface 31b side of the first insulating layer 31 is arranged to face the ignition source. The first insulating material of the first insulating layer 31 is, for example, WDS (registered trademark). The first insulating material is, for example, a material with a low first thermal conductivity. The thermal conductivity of WDS is, for example, about 0.04 W / m·K at 800°C. WDS is a high insulating material with low thermal conductivity even in high temperature regions. The first insulating material is, for example, formed of fine fumed silica and a substance that does not transmit infrared rays. The first insulating material has, for example, a micropore structure in which countless fine holes with a diameter of 100 nm or less are formed, which regulates the movement of air molecules. The first insulating material has lower elasticity and poorer workability than the second insulating material (AES) of the second insulating layer 32.

[0029] The heat absorption layer 4 is provided on the inner surface 32a side of the second insulating layer 32. The second insulating layer 32 is formed to a thickness that allows the heat transferred in the first temperature range by the first insulating layer 31 to be lowered to a second temperature range in which the heat absorption material of the heat absorption layer 4 exerts a heat absorption effect and transferred to the heat absorption layer 4.

[0030] The second insulating material of the second insulating layer 32 is formed in a sheet shape, for example, AES (alkaline earth silicate) wool. The second insulating material is, for example, a mineral fiber insulating material having a chemical composition mainly composed of high-purity silica, calcia, and magnesia. The second insulating material may be formed of bioabsorbable fibers that can be decomposed or absorbed in the body. The second thermal conductivity of the second insulating material is higher than the first thermal conductivity of the first insulating material of the first insulating layer 31. The second insulating material transfers heat faster than the first insulating material. The thermal conductivity of AES is higher than that of the above-mentioned WDS, particularly in the high temperature range (800°C) compared to the low temperature range (400°C).

[0031] The heat absorption layer 4 is disposed on the inner periphery of the outer peripheral insulation layer 3, and is formed of a heat absorption material that maintains heat in the second temperature range within the second temperature range based on an endothermic reaction. A step portion 4A formed at the inner periphery end portion 4c of the heat absorption layer 4 is disposed in a state where it is covered from the inner periphery side by the existing insulation material 2. The outer surface 4b side of the heat absorption layer 4 faces the inner surface 32a of the second insulation layer 32.

[0032] The heat absorption layer 4 exerts a heat absorption effect by absorbing heat in the second temperature range transferred from the second insulating layer 32 based on a chemical reaction. The heat absorption layer 4 suppresses a temperature rise, maintains the second temperature range, and transfers the heat to the inner circumferential side.

[0033] In this embodiment, the heat absorption layer 4 is made of two stepped heat absorption layers 41 and 42. The two-layer heat absorption layer 4 is a first heat absorption layer 41 on the outer periphery side and a second heat absorption layer 42 on the inner periphery side. The second heat absorption layer 42 on the inner periphery side has a smaller width dimension than the first heat absorption layer 41 on the outer periphery side in cross section. The step portions 41A and 42A of the first heat absorption layer 41 and the second heat absorption layer 42 are covered by the existing thermal insulation material 2 from the inner periphery side.

[0034] The first heat absorption layer 41 and the second heat absorption layer 42 are formed by arranging a plurality of bag-shaped heat absorption materials (not shown) in layers. The heat absorption material (not shown) is formed by accommodating a heat absorption material in an accommodation space formed in a bag shape by a heat insulation sheet material. The heat insulation sheet is formed, for example, by a woven fabric made of fire-resistant fibers such as aluminum glass cloth. The pair of heat insulation sheets are provided with perforations, for example, at predetermined rectangular units, and the heat absorption material is arranged in a matrix of a plurality of rectangular small bags.

[0035] The heat absorbing material is formed of a powder material that does not contain moisture in order to prevent the heat absorbing effect from decreasing due to drying over time. The heat absorbing material is, for example, a powder material that separates water based on a chemical reaction when heated and exhibits an endothermic reaction. The heat absorbing material is, for example, formed of aluminum hydroxide (Al(OH)3) powder particles. The heat absorbing material is, for example, a powder crystal with a median particle size of about 10 μm to 100 μm.

[0036] Aluminum hydroxide is stable below 200°C, but in the temperature range of 200°C to 350°C, water molecules H2O are violently separated and decomposed to become Al2O3, and an endothermic reaction occurs at that time. The first heat absorption layer 41 and the second heat absorption layer 42 are formed to a layer thickness of, for example, 10 mm. Therefore, the layer thickness of the heat absorption layer 4 is, for example, 20 mm. An inner circumferential heat insulating layer 5 is provided adjacent to the inner surface 4a side of the heat absorption layer 4. The heat absorption layer 4 transfers heat in the second temperature range to the inner circumferential heat insulating layer 5.

[0037] The inner insulating layer 5 is disposed facing the inner surface 4a of the heat absorption layer 4, and the heat of the heat absorption layer 4 is transferred thereto. The inner insulating layer 5 is formed from the same material (second insulating material) as the second insulating layer 32 of the outer insulating layer 3. A fire-resistant protection object K is disposed on the inner surface 5a side of the inner insulating layer 5. That is, the second insulating material of the inner insulating layer 5 is the same as the second insulating material of the second insulating layer 32 described above. In this embodiment, the inner insulating layer 5 (51, 52) is formed by stacking two layers of the second insulating material.

[0038] Next, a method for repairing an existing thermal insulation material 2 using the above-mentioned fireproof repair wrapping material 1 will be described with reference to Figures 3(a) to (c). Here, in Figures 3(a) to (c), the lower side of the paper surface is the outer periphery side, and the upper side of the paper surface is the inner periphery side.

[0039] Fig. 3(a) shows a state where there is a damaged area P on part of the outer periphery (heating side) of the existing insulation material 2. As shown in Fig. 3(a), when there is a damaged area P on the outer periphery of the existing insulation material 2 and it is necessary to carry out partial repairs on the existing insulation material 2, as shown in Fig. 3(b), the damaged area P that requires replacement of the insulation is entirely removed and a repair area 2A is provided. In this case, the repair area 2A is cut out across the entire thickness of the existing insulation material 2 to reach the fire-resistant protection target K, and is cut out in a stepped shape so that the notch width becomes smaller from the outer periphery on the ignition side toward the inner periphery.

[0040] Next, as shown in Figures 2 and 3(c), a new fireproof repair wrapping material 1 made of a different material from the existing insulation material 2 is placed on the cut-out portion (repair portion 2A). The fireproof repair wrapping material 1 is placed by wrapping it from the inner circumference side to the outer circumference side. That is, first, two inner circumference insulation layers 5 (51, 52) are placed in a position that will be the non-heated surface facing the fireproof protection object K (see Figure 2).

[0041] Thereafter, the heat absorption layer 4 (second heat absorption layer 42, first heat absorption layer 41) and the outer peripheral insulation layer 3 (second insulation layer 32, first insulation layer 31) are arranged in this order on the outer peripheral side of the inner peripheral insulation layer 5. At this time, the step portion 4A at the inner peripheral end portion 4c formed in the heat absorption layer 4 is covered from the inner peripheral side by the existing insulation material 2. This makes it possible to repair the existing insulation material 2 using the repair fire-resistant wrapping material 1.

[0042] Next, the operation of the method for repairing an existing thermal insulation material will be described in detail with reference to Figs. 1, 2 and 3(a) to (c). The method for repairing an existing thermal insulation material according to this embodiment includes a step of cutting out the existing thermal insulation material 2 to be repaired to form a repair portion 2A, and a step of installing a new repair fireproof wrapping material 1 in the repair portion 2A. The repair portion 2A is cut out in a stepped shape so that the notch width becomes smaller from the outer periphery side, which is the ignition side, toward the inner periphery side in a cross-sectional view. The fireproof wrapping material for repair 1 includes a first insulating layer 31 provided on the outermost periphery of the repair part 2A and made of a first insulating material having a first thermal conductivity that reduces the heat transferred from the ignition source to a first temperature range, a second insulating layer 32 arranged on the inner periphery side of the first insulating layer 31 and made of a second insulating material having a second thermal conductivity that reduces the heat transferred from the first insulating layer 31 to a second temperature range, a heat absorption layer 4 formed of a heat absorption material that maintains the heat in the second temperature range at the second temperature range based on an endothermic reaction, and an inner periphery insulating layer 5 arranged on the inner periphery side of the heat absorption layer 4 to which the heat of the heat absorption layer 4 is transferred, formed of the same material as the first insulating layer 31, and having a fireproof protection target K arranged on the inner periphery side. The step portion 4A of the inner periphery end portion 4c of the heat absorption layer 4 is arranged in a state of being covered from the inner periphery side by the existing insulating material 2.

[0043] According to the method for repairing an existing insulation material of this embodiment, when replacement such as partial repair is required in the existing insulation material 2, the portion requiring replacement is cut out and removed in a stepped manner so that the notch width decreases from the outer periphery of the ignition side toward the inner periphery, and a new fireproof repair wrapping material 1 made of a different material from the existing insulation material 2 is placed in the removed portion, thereby repairing the existing insulation material 2. In this way, the method for repairing an existing insulation material 2 of this embodiment is a method in which a part of the existing insulation material 2 is partially cut out and repaired partially, so that the labor and time can be reduced by the simple repair work, and an increase in the cost of parts can be suppressed.

[0044] In addition, in this embodiment, the step portion 4A of the inner end portion 4c of the heat absorption layer 4 located in the center of the thickness direction of the repair fire-resistant wrapping material 1 is arranged in a state where it is covered from the inner side by the existing insulation material 2, so that heat transfer from the heat absorption layer 4 to the non-heated surface side is suppressed and the temperature rise can be reduced, and the fire resistance performance can be improved by repairs using the repair fire-resistant wrapping material 1.

[0045] Furthermore, in this embodiment, multiple step portions 4A are formed in the heat absorption layer 4, and each of these is arranged in a state where it is covered by the existing insulation material 2, so that heat transfer from the heat absorption layer 4 to the non-heated surface side is more effectively suppressed and the temperature rise can be reduced.

[0046] In this embodiment, the second insulating layer 32 made of a second insulating material having a second thermal conductivity higher than that of the first insulating material is interposed between the first insulating layer 31 and the heat absorbing layer 4. As a result, the first insulating layer 31 having a first thermal conductivity lower than that of the second insulating layer is provided on the heating side of the second insulating layer 32, so that the second layer thickness of the second insulating layer 32 can be formed thinner than when the heating side is formed only with the second insulating layer 32 so as to have the same level of fire resistance, and the weight can be reduced. In addition, according to this embodiment, the first layer thickness of the first insulating layer 31 and the second layer thickness of the second insulating layer 32 are formed so that the heat absorbing layer 4 has a heat absorbing effect, so that the fire resistance can be guaranteed.

[0047] In this embodiment, the first layer thickness of the first insulating layer 31 and the second layer thickness of the second insulating layer 32 of the peripheral insulating layer 3 are adjusted so that the second insulating layer 32 transmits heat in the second temperature range to the heat absorption layer 4 during a predetermined fire resistance performance time after ignition, and uses up the heat absorption performance of the heat absorption layer 4. With this configuration, the heat absorption layer 4 uses up its heat absorption effect during the fire resistance performance time, so that excess heat absorption material in the heat absorption layer 4 can be reduced, making it possible to reduce weight.

[0048] In this embodiment, the existing insulation material 2 is wrapped around the fire-resistant protection object K in the circumferential direction. The repair portion 2A is formed around the entire circumference of the existing insulation material 2. Therefore, the repair fire-resistant wrapping material 1 can be used to uniformly repair the repair portion 2A, which is obtained by cutting out the existing insulation material 2 around the entire circumference in the circumferential direction.

[0049] In this embodiment, the heat absorbing material of the heat absorbing layer 4 is made of a powder material that separates water based on a chemical reaction when heated and exhibits an endothermic reaction. Therefore, since the heat absorbing material does not contain moisture under normal conditions, performance degradation due to drying does not occur, and performance can be continuously maintained over time.

[0050] Next, examples conducted to verify the effectiveness of the method for repairing existing insulation according to the above-described embodiment will be described below.

[0051] (Example) In the examples, a repair performance test was conducted on a repair fire-resistant wrapping material that was repaired using a repair method in a non-stepped shape without any steps in the existing insulation material of the above-mentioned embodiment, and the effect of the stepped repair fire-resistant wrapping material was confirmed.

[0052] In the following performance test, a practical test was conducted to examine the effect of the repair fireproof wrapping material on the repair performance, in which a repair fireproof wrapping material 60 was provided in a non-stepped shape from the outer periphery side to the inner periphery side as shown in Fig. 4. In the practical test, a test piece 100 was prepared, and a fire resistance test was performed to measure the temperature of the non-heated surface. The repair fireproof wrapping material 60 shown in Fig. 4 is a non-stepped shape that does not have steps in each layer in the repair fireproof wrapping material 1 of the above-mentioned embodiment.

[0053] The test specimen 100 shown in FIG. 4 includes an existing insulation material 20 and a repair fireproof wrapping material 60. The boundary between the existing insulation material 20 and the repair fireproof wrapping material 60 is non-step-shaped, simulating a surface perpendicular to the cable axial direction. The existing insulation material 20 is made up of six layers. The repair fireproof wrapping material 60 is laminated in a total of six layers (in the order of a first layer 61, a second layer 62, a third layer 63, a fourth layer 64, a fifth layer 65, and a sixth layer 66 from the lower heating surface side). Reference numeral 10 denotes a heat source provided on the heating surface side located on the lower side of the test specimen 100.

[0054] The first layer 61 is made of the same material as the first insulating material of the first insulating layer 31 of the peripheral insulating layer 3 in the above-mentioned embodiment, and WDS (registered trademark) is used. The second layer 62, the fifth layer 65 and the sixth layer 66 are made of the same material as the second insulating material of the second insulating layer 32 of the peripheral insulating layer 3 in the above-mentioned embodiment, and AES (alkaline earth silicate) wool is used. The third layer 63 and the fourth layer 64 are made of the same material as the heat absorbing material of the heat absorbing layer 4 in the above-mentioned embodiment, and ALGC (aluminum glass cloth) is used here.

[0055] In the test specimen 100 shown in FIG. 4, the reference numerals 1 to 9 indicate temperature measurement points. Among them, the measurement points 1 to 3 are temperature measurement points on the non-heated surface. The measurement points 4 to 6 are temperature measurement points between the second and third layers from the inner periphery side (upper side of the paper). And the measurement points 7 to 9 are temperature measurement points between the second and third layers from the outer periphery side (lower side of the paper). The measurement points 3, 6, and 9 are temperature measurement points in the existing insulation material 20. The measurement points 2, 5, and 8 are temperature measurement points in the repair refractory wrapping material 60. Furthermore, the measurement points 1, 4, and 7 are temperature measurement points in the boundary portion between the existing insulation material 20 and the repair refractory wrapping material 60. That is, the measurement points 4 and 5 are temperature measurement points located on the inner periphery side of the fourth layer 64 of the heat absorbing material. The measurement points 7 and 8 are temperature measurement points located on the outer periphery side of the third layer 63 of the heat absorbing material.

[0056] Fig. 5 is a graph showing the test results of the implemented experiment, with the horizontal axis representing time (min) and the vertical axis representing temperature (°C), showing the temperature transition over time at each of the measurement points 1 to 9 and the heat source 10.

[0057] As a result of the fire resistance test, when the temperatures of measurement points 7, 8, and 9 on the heated side at the end of the test are compared, it is found that measurement point 8 located on the repair fireproof wrapping material 60 has a lower temperature rise than measurement points 7 and 9 located on the existing insulation material 20 side. Also, when measurement points 4, 5, and 6 located in the center part in the thickness direction (inner and outer periphery direction) are compared, it is found that measurement point 5 located on the repair fireproof wrapping material 60 has a lower temperature rise than measurement points 4 and 6 located on the existing insulation material 20 side, as in the case of the heated side. On the other hand, when measurement points 1, 2, and 3 on the non-heated side are compared, it is found that measurement point 2 located on the repair fireproof wrapping material 60 has a higher temperature rise than measurement points 1 and 3 located on the existing insulation material 20 side.

[0058] 5, it can be seen that heat leaks from measurement point 4 in the direction of measurement point 2. In order to prevent this heat leakage, it is effective to cover the non-heated surface side (inner circumference side) of the fourth layer 64, which is a heat absorbing material, on the existing insulation material 20 side with the existing insulation material 20, that is, to have a stepped configuration in which the fourth layer 64 (including the third layer 63), which is a heat absorbing material of the repair fire-resistant wrapping material 60 on the non-heated side, becomes smaller.

[0059] For this reason, as in the embodiment shown in Figures 3(a) to (c) above, by cutting the existing insulation material 2 into a stepped shape and wrapping the cut repair portion 2A with repair fire-resistant wrapping material 1, and further arranging the existing insulation material 2 so as to cover the non-heated surface of the heat absorption layer 4 (corresponding to the third layer 63 and the fourth layer 64 of test specimen 100) using a heat absorption material from the inner periphery, heat transfer to the non-heated surface side is suppressed more than in the case of a non-stepped shape such as test specimen 100, thereby reducing the temperature rise, and it can be confirmed that the structure repaired with the repair fire-resistant wrapping material meets the fire resistance standards.

[0060] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention.

[0061] For example, the thickness of each layer of the repair fireproof wrapping material 1 can be appropriately set depending on the material of each layer. In the present embodiment, the peripheral insulation layer 3 is configured to have two layers, the first insulation layer 31 and the second insulation layer 32, but is not limited thereto, and may be, for example, only the first insulation layer 31, or the peripheral insulation layer 3 may have three or more layers. Moreover, the number and thickness of the heat absorbing layer 4 and the inner peripheral heat insulating layer 5 can also be changed as appropriate. [Explanation of symbols]

[0062] 1 repair fireproof wrapping material, 2 existing insulation material, 2A repair part, 3 outer peripheral insulation layer, 31 first insulation layer, 32 second insulation layer, 4 heat absorption layer, 4A step part, 4a inner surface, 4b outer surface, 4c inner peripheral end part, 41 first heat absorption layer, 42 second heat absorption layer, 5 inner peripheral insulation layer, K fireproof protection object

Claims

1. A method for repairing an existing insulation material formed in a layer on an object to be protected from fire, comprising the steps of: A step of cutting out the existing insulation material to be repaired to form a repair portion; and installing a new repair refractory wrapping material on the repaired portion. The repair portion is cut out in a stepped shape so that the cutout width becomes smaller from the outer circumferential side, which is the ignition side, toward the inner circumferential side in a cross-sectional view, The repair fireproof wrapping material is a first insulating layer provided on the outermost periphery of the repair portion and made of a first insulating material having a first thermal conductivity that reduces heat transferred from an ignition source to a first temperature range; a second insulating layer disposed on the inner periphery side of the first insulating layer and made of a second insulating material having a second thermal conductivity that reduces the heat transferred from the first insulating layer to a second temperature range; a heat absorption layer disposed on the inner circumferential side of the second heat insulating layer and formed of a heat absorption material that maintains the second temperature range in the second temperature range based on an endothermic reaction of heat in the second temperature range; an inner periphery insulation layer that is disposed on the inner periphery side of the heat absorption layer, to which heat from the heat absorption layer is transferred, and that is formed of the same material as the second insulation layer and to which the fire-resistant protected object is disposed on the inner periphery side; A method for repairing existing insulation, in which a step portion at an inner circumferential end portion of the heat absorption layer is positioned in a state in which it is covered from the inner circumferential side by the existing insulation material.

2. The heat absorption layer is formed in a plurality of steps, and each step is covered from the inner circumferential side by the existing insulation material. A method for repairing existing insulation according to claim 1.

3. The first insulation layer and the second insulation layer are formed of the same material. A method for repairing existing insulation according to claim 1.

4. The first thickness of the first insulating layer and the second thickness of the second insulating layer are adjusted so that the second insulating layer transfers heat in the second temperature range to the heat absorption layer during a predetermined fire resistance time after ignition, and uses up the heat absorption performance of the heat absorption layer. The method for repairing existing insulation according to claim 3.

5. The existing insulation material is wrapped around the fire-resistant protected object in a circumferential direction, The repair portion is formed around the entire periphery of the existing insulation material. A method for repairing an existing insulation material according to any one of claims 1 to 4.

6. The heat absorbing material of the heat absorbing layer is formed of a powder material that separates water based on a chemical reaction when heated and exhibits an endothermic reaction. A method for repairing an existing insulation material according to any one of claims 1 to 4.

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