Heat insulation lining, heat insulation lining construction method, skid pipe and heated slab production method

Abstract

To provide a heat insulation lining which suppresses condensation while reducing a heat removal amount from a cooling member, increasing the durability of a heat insulation sheet, a heat insulation lining construction method, a skid pipe having the heat insulation lining, and a heated slab production method for heating a steel slab using the skid pipe to a heating furnace.SOLUTION: Disclosed is a heat insulation lining comprising: a heat insulation sheet provided at the outside of a cooling member; an inner layer provided between the cooling member and the heat insulation sheet and suppressing the condensation of the heat insulation sheet; an outer layer provided at the outside of the heat insulation sheet and made of a moisture-free member; and an additional layer optionally provided between the outer layer and the heat insulation sheet. Also, disclosed is a heat insulation lining construction method in which the inner layer is provided at the outside of the cooling member, the heat insulation sheet is provided at the outside of the inner layer, the outer layer is provided at the outside of the heat insulation sheet, and the additional layer is optionally provided between the outer layer and the heat insulation sheet. Also, disclosed is a skid pipe in which the heat insulation lining is formed around a water-cooling pipe in a cyclic structure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an insulating lining for covering a cooling member, a method for applying the insulating lining, a skid pipe having the insulating lining, and a method for manufacturing a heated slab in which a skid pipe is used in a heating furnace to heat a steel slab. [Background technology]

[0002] In the hot rolling process in steelworks, a heating furnace is used to heat steel slabs, which are then rolled to produce thin plates. In such heating furnaces, a platform called a skid is installed on which the steel slabs are placed to transport them from the charging side to the discharging side.

[0003] The skid is equipped with skid pipes called beams or posts, and the steel slab is placed on the top of the skid pipe, and the skid moves up and down and left and right to transport the steel slab. The skid pipe has a water-cooled pipe as a cooling member. The water-cooled pipe is a piping-like member through which cooling water flows, and part of the energy input to the heating furnace when the steel slab is heated is also transmitted to the cooling water flowing inside the water-cooled pipe. For this reason, a heat-insulating lining with high thermal insulation properties is installed around the water-cooled pipe. If the heating furnace is used for a long period of time, the heat-insulating lining installed around the water-cooled pipe will fall off due to cracks or the like. If the heat-insulating lining falls off, the exposed part of the water-cooled pipe will lose thickness and water will leak. Therefore, the heat-insulating lining that constitutes the skid pipe is required to have both high durability and high thermal insulation properties.

[0004] In order to solve these problems, various types of thermal insulation linings have been proposed. For example, Patent Document 1 discloses a thermal insulation lining for such a skid pipe, which is provided on the outer periphery of a water-cooled pipe and is composed of a thermal insulation layer part consisting of an inner layer and an outer layer, and a laminated structure provided on the outer periphery of the thermal insulation layer part.

[0005] Patent Document 2 discloses an insulating lining for molten metal containers such as ladles, converters, and torpedo cars used in the steelmaking process, which aims to prevent a decrease in the insulating effect of microporous insulation material and prevents condensation that occurs on the inner surface of the steel shell from coming into contact with the microporous insulation material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-173089 A [Patent Document 2] JP 2013-044510 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when attempting to apply the above-mentioned conventional technology to a skid pipe used in a heating furnace, the following problems arise. In Patent Document 1, a highly insulating fumed silica or microporous material is used as the inner layer of the insulation layer, and a highly heat-resistant ceramic fiber is used as the outer layer. However, the microporous insulation sheet deteriorates due to condensation. When a microporous insulation sheet is provided at a location in contact with a water-cooled pipe, the inner surface of the insulation sheet is condensed due to cooling by the cooling water, and the insulation sheet deteriorates and peels off, resulting in a problem of reduced durability of the insulation lining.

[0008] In Patent Document 2, the microporous insulation sheet is placed between a water-absorbent insulation material having heat resistance and water absorption properties and a permanent refractory so that the microporous insulation sheet does not come into contact with condensation, and an unshaped refractory is used as the wear refractory that directly contacts the molten metal. However, when the molten metal container is in operation, the moisture contained in the unshaped refractory moves to the steel shell side, which has a lower temperature, so even if the microporous insulation sheet is placed between the water-absorbent insulation material and the permanent refractory, the microporous insulation sheet becomes wet. Therefore, the deterioration of the insulation properties of the microporous material is unavoidable.

[0009] The present invention has been made to solve the above problems of the prior art, and its object is to provide an insulating lining and an application method thereof that can reduce the amount of heat dissipated from the cooling member while suppressing condensation and increasing the durability of the insulating sheet. In addition, the present invention provides a skid pipe having the insulating lining, and a manufacturing method for a heated slab in which the skid pipe is used in a heating furnace to heat a steel slab. [Means for solving the problem]

[0010] The present invention, which advantageously solves the above problems, is configured as follows. [1] An insulating lining that covers the outer periphery of a cooling member, comprising: a microporous insulating sheet provided on the outside of the cooling member; an inner layer made of a material having insulating properties and provided between the cooling member and the insulating sheet to suppress condensation of the insulating sheet; an outer layer made of a material that is insulating and fire-resistant and does not contain moisture and provided on the outside of the insulating sheet; and optionally an additional layer provided between the outer layer and the insulating sheet. [2] In the above [1], the insulating lining satisfies at least one of the following: the insulating sheet is microporous; the inner layer is a fiber blanket or fiber paper; and the outer layer is an insulating board, a fiber blanket or a fiber paper. [3] In the above [1] or [2], the ambient temperature outside the outer layer is in an environment of 800°C or higher and 2000°C or lower, the outer layer is provided so that the temperature of the outer surface of the insulation sheet is 750°C or lower, and the inner layer is provided so that the temperature of the inner surface of the insulation sheet is higher than 80°C. [4] The heat insulating lining according to any one of the above [1] to [3], wherein the outer layer has a thickness of 50 mm or more. [5] The heat insulating lining according to any one of the above [1] to [4], wherein the heat insulating sheet has a thickness of 10 mm or less. [6] A method for applying an insulating lining to cover the outer periphery of a cooling member, comprising providing an inner layer made of an insulating material on the outside of the cooling member, providing a microporous insulating sheet on the outside of the inner layer, providing an outer layer made of an insulating and fire-resistant material on the outside of the insulating sheet, and optionally providing an additional layer between the outer layer and the insulating sheet. [7] A skid pipe in which the insulating lining described in any one of [1] to [5] above is formed in an annular structure around a water-cooled pipe as a cooling member. [8] A method for manufacturing a heated slab, comprising using the skid pipe described in [7] above in a heating furnace to heat a steel slab. Effect of the Invention

[0011] According to the present invention, by providing the insulating lining of the cooling member from the inside out in the order of an inner layer, a microporous insulating sheet, optionally an additional layer, and an outer layer, it is possible to reduce the amount of heat dissipated from the cooling member while increasing the durability of the insulating sheet by suppressing condensation. [Brief description of the drawings]

[0012] [Figure 1] 1 is a configuration diagram showing a cross-sectional structure of a thermal insulating lining according to one embodiment of the present invention. [Diagram 2] FIG. 4 is a schematic diagram showing a cross-sectional structure of a heat insulating lining according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The heat insulating lining according to the present embodiment will be described below with reference to the drawings. Note that the drawings are schematic and may differ from the actual ones. Furthermore, the following embodiments are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and are not intended to limit the configuration to the following. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0014] <Thermal insulation lining> The insulating lining according to this embodiment comprises, in order from the cooling member side, an inner layer, a microporous insulating sheet, and an outer layer in layers. The inner layer is made of a material having thermal insulation properties and is provided between the cooling member and the insulating sheet to suppress condensation on the insulating sheet. The outer layer is made of a material having thermal insulation properties and fire resistance and does not contain moisture and is provided on the outside of the insulating sheet. Optionally, an additional layer may be provided between the outer layer and the insulating sheet.

[0015] The heat insulating lining according to this embodiment is suitable for protecting a cooling member (hereinafter, referred to as a water-cooled pipe) installed in a heating furnace. Cooling water with a temperature of about 30 to 70° C. flows in the water-cooled pipe as a cooling medium.

[0016] 1, the insulating lining 10 according to this embodiment is provided so as to cover the outer periphery of a water-cooled pipe P, and from the inside (the water-cooled pipe side) an inner layer 1, an insulating sheet 2, and an outer layer 3 are arranged in this order so as to have an annular structure in the radial direction of the water-cooled pipe P. The water-cooled pipe P and the insulating lining 10 form a skid pipe.

[0017] The inner layer 1 is made of a material having heat insulating properties. Specifically, as an example, the inner layer 1 is preferably made of a fiber blanket or fiber paper.

[0018] The heat insulating sheet 2 is made of a fine pore, and is preferably constituted by, for example, a microporous sheet having heat insulating properties.

[0019] The outer layer 3 is made of a material having heat insulation and fire resistance. The outer layer 3 does not use a material that contains moisture during the manufacturing process, such as castable. Specifically, the outer layer is preferably made of an oxide-based material, such as an Al2O3-SiO2 insulation board, fiber blanket, or fiber paper that does not contain moisture.

[0020] In this embodiment, a finely porous, for example, microporous, insulating sheet 2 is provided on the outside of the water-cooled pipe P to ensure high thermal insulation of the insulating lining 10. At the same time, an inner layer 1 is provided on the inside (water-cooled pipe side) of the insulating sheet 2, and an outer layer 3 is provided on the outside (furnace atmosphere side) of the insulating sheet 2, thereby protecting the microporous insulating sheet 2 from both sides and maintaining the high thermal insulation of the insulating sheet 2.

[0021] When the insulating lining 10 according to this embodiment is used in a heating furnace, that is, during operation, the atmospheric temperature in the heating furnace outside the outer layer 3 is 800°C or higher and 2000°C or lower. In addition, when cooling water is flowing in the water-cooled pipe P, it is preferable to provide the outer layer 3 and the inner layer 1 so that the temperature of the outer surface of the insulating sheet 2 is 750°C or lower and the temperature of the inner surface of the insulating sheet 2 is higher than 80°C.

[0022] When the insulating lining is applied under the above conditions, the temperature of the outer surface of the insulating sheet will be 750°C or lower, and the temperature of the inner surface will be above 80°C. In this way, by keeping the temperature of the outer surface of the insulating sheet at 750°C or lower, the insulating sheet can be protected from heat, and by keeping the temperature of the inner surface above 80°C, condensation on the insulating sheet can be prevented. In other words, the insulating sheet will not deteriorate and can continue to exert its insulating effect while maintaining the condition it had before the heating furnace started operating, and the amount of heat dissipated from the water-cooled pipe can be significantly reduced, while significantly extending the period from the start of operation of the heating furnace to repair (hereinafter referred to as the continuous operating period).

[0023] On the other hand, if the heat insulating sheet 2 is arranged radially inward of the inner layer 1 having a predetermined thickness that satisfies the above conditions, that is, too close to the water-cooled pipe P, the temperature of the inner surface of the heat insulating sheet 2 will be cooled to 80°C or less by the cooling water flowing through the water-cooled pipe P. This may cause condensation on the heat insulating sheet 2 during operation of the heating furnace, leading to deterioration and peeling off. If the heat insulating sheet peels off due to condensation, the continuous operating period of the heating furnace will be significantly shortened.

[0024] Even if the insulating lining 10 has a two-layer structure consisting of the outer layer 3 and the insulating sheet 2 without providing the inner layer 1, the temperature of the inner surface of the insulating sheet 2 will be below 80°C as described above, causing condensation in the insulating sheet 2 during operation, which will deteriorate and peel off.

[0025] Furthermore, if the insulating lining 10 has a two-layer structure of the inner layer 1 and the outer layer 3 without providing the microporous insulating sheet 2, the insulating properties are insufficient. Therefore, the heat of the furnace is transferred to the water-cooled pipe P, the surface temperature of the water-cooled pipe P increases, and the amount of heat dissipated from the water-cooled pipe P increases. In other words, the energy loss becomes too large.

[0026] In the above environment of the ambient temperature and water cooling temperature of the heating furnace, when the temperature of the outer surface of the heat insulating sheet 2 is 750°C or less and the temperature of the inner surface of the heat insulating sheet 2 drops to 80°C or less, it is considered that the water vapor on the inner surface of the heat insulating sheet will turn to water and condensation will occur, according to the amount of saturated water vapor at 80°C on the saturated water vapor pressure curve. Therefore, it is preferable that the temperature of the outer surface of the heat insulating sheet is 750°C or less and the temperature of the inner surface of the heat insulating sheet is above 80°C.

[0027] The radial thickness of the outer layer 3 that satisfies the above conditions is preferably 50 mm or more. The radial thickness of the inner layer 1 that satisfies the above conditions is preferably 0.5 mm or more. In this case, the radial thickness of the heat insulating sheet 2 is preferably 10 mm or less.

[0028] When the radial thickness (layer thickness) of the outer layer 3 is 50 mm or more, the amount of erosion of the iron oxide film (hereinafter referred to as scale) into the outer layer 3 due to the surface oxidation of the steel slab during operation is relatively small, and a continuous operation period can be ensured. Therefore, the radial thickness (layer thickness) of the outer layer 3 is preferably 50 mm or more. There is no upper limit to the radial thickness of the outer layer 3, but in consideration of the equipment connection, the radial thickness of the outer layer 3 is preferably 100 mm or less.

[0029] Furthermore, when the radial thickness of the inner layer 1 is 0.5 mm or more, the thickness of the inner layer 1 is sufficient for thermal insulation performance, the amount of heat removed from the water-cooled pipe P can be reduced, and the temperature of the inner surface side of the thermal insulation sheet can be ensured. Therefore, the radial thickness of the inner layer 1 is preferably 0.5 mm or more. If the radial thickness of the inner layer 1 is too large, there is a risk that the temperature of the thermal insulation sheet will become too high, so the radial thickness of the inner layer 1 is preferably 50 mm or less. The radial thickness of the inner layer 1 is more preferably 5 mm or more, and more preferably 20 mm or less.

[0030] Furthermore, when the radial thickness (layer thickness) of the heat insulating sheet 2 is 10 mm or less, the heat insulating sheet 2 conforms well to the curved shape of the surface of the water-cooled pipe P, and the heat insulating sheet 2 is easy to wrap and highly workable. As a result, gaps are less likely to form between the inner layer 1 and the outer layer 3. This further reduces the amount of heat dissipated from the water-cooled pipe P. Therefore, the radial thickness of the heat insulating sheet 2 is preferably 10 mm or less. In consideration of ensuring heat insulation, the radial thickness of the heat insulating sheet 2 is preferably 3 mm or more, and more preferably 5 mm or more.

[0031] In the above embodiment, the insulating lining 10 is exemplified as having a three-layer structure consisting of an inner layer 1, an insulating sheet 2, and an outer layer 3. However, in other embodiments of the present invention, the insulating lining is not limited to a three-layer structure, and may have a structure of four or more layers.

[0032] Specifically, as shown in FIG. 2, for example, in another embodiment, an additional layer 4 may be provided on the outside of the heat insulating sheet 2 and on the inside of the outer layer 3. As an example, the additional layer 4 is made of a fiber blanket or fiber paper, similar to the inner layer 1. By making the heat insulating lining 10 have a four-layer structure in this way, the amount of heat dissipated from the water-cooled pipe P can be further reduced, and the durability of the heat insulating sheet 2 can be further improved. This not only reduces the amount of heat dissipated from the water-cooled pipe P, but also suppresses peeling or falling off of the heat insulating lining 10 due to cracks or fissures in the heat insulating sheet 2. EXAMPLES

[0033] The effects of this embodiment will be specifically described below based on examples, but the present invention is not limited to these examples.

[0034] As an example of this embodiment, different insulating linings with a total thickness of 100 mm were applied to the water-cooled pipe of a heating furnace, and the insulating effect of each insulating lining was quantitatively evaluated. The temperature of the boundary between each insulating layer constituting the insulating lining and the iron shell temperature of the water-cooled pipe were continuously measured during operation by installing a thermocouple when the insulating lining was applied. The amount of heat removed from the water-cooled pipe was calculated from the following formula (1). Q = h × ΔT × A (1) In the formula, Q: amount of heat removed [W], h: Heat transfer coefficient [W / (m 2 ·°C)], ΔT: Difference between the surface temperature of the water-cooled pipe and the outside air temperature [℃] A: Surface area of ​​water-cooled pipe [m 2 ] It is.

[0035] Regarding the amount of scale erosion, the insulation lining was collected after the operation was finished, and a sample of 50 mm x 50 mm x 50 mm was cut from the surface exposed to the furnace atmosphere. The distribution of Fe elements was evaluated by EPMA mapping analysis in the radial direction from the furnace atmosphere side to the water-cooled pipe for the sample.

[0036] The evaluation results of the insulation effect are shown in Tables 1 to 6. In the tables, the insulation linings are indicated as the 1st, 2nd, 3rd, and 4th layers in order from the outside (furnace atmosphere side). Also shown are the results of No. 1, an insulation lining made of a single layer of fire-resistant insulating castable, as a conventional insulation lining.

[0037] [Table 1]

[0038] In No. 2 and 3 in Table 1, an 80 mm thick Al2O3-SiO2 insulation board and fiber blanket were used as the outer layer (first layer), and a 15 mm thick fiber blanket was used as the inner layer (third layer). A 5 mm thick microporous insulation sheet was placed between the inner and outer layers (second layer) to create a three-layer insulation lining. Note that CaO·6Al2O3 insulation boards can also be used instead of Al2O3-SiO2.

[0039] In No. 4 and 5, an 80 mm thick Al2O3-SiO2 insulation board and fiber blanket were used as the outer layer (first layer), and a 5 mm thick fiber paper was used as the inner layer (fourth layer). A 5 mm thick microporous insulation sheet was placed on the outside of the inner layer (third layer), and an additional layer of 10 mm thick fiber paper was placed between the insulation sheet and the outer layer (second layer), creating a four-layer insulation lining.

[0040] As shown in Table 1, in No. 2 and No. 3, the temperature of the outer surface of the insulation sheet was between 630°C and 640°C, and the temperature of the inner surface was 198°C. As a result, the insulation sheet did not condense and maximized its inherent insulation effect. Compared to the insulation lining of the conventional example (No. 1), the amount of heat dissipated from the water-cooled pipe was reduced by 85%, and the continuous operation period of the heating furnace was significantly extended to about three years.

[0041] In No. 4 and 5, the temperature of the outer surface of the insulation sheet was 610°C, and the temperature of the inner surface was 197°C. As a result, the insulation sheet did not condense, and it maximized its inherent insulation effect. Compared to the conventional insulation lining (No. 1), the amount of heat dissipated from the water-cooled pipes was reduced by 90% to 92%, and the continuous operation period was significantly extended to about three years.

[0042] On the other hand, in No.6 and No.7, 80mm thick CaO·6Al2O3 and Al2O3-SiO2 castables were used as the outer layer (first layer), and 15mm thick fiber blanket was used as the inner layer (third layer).A 5mm thick microporous insulation sheet was placed between the inner and outer layers (second layer), forming a three-layer insulation lining.

[0043] In No. 8, a four-layer insulation lining was installed, consisting of an 80 mm thick CaO·6Al2O3 castable as the outer layer (1st layer), a 5 mm thick fiber paper as the inner layer (4th layer), a 5 mm thick microporous insulation sheet on the outside of the inner layer (3rd layer), and an additional layer of 10 mm thick fiber paper between the insulation sheet and the outer layer (2nd layer).

[0044] As shown in Table 1, in Nos. 6 to 8, the temperature of the outer surface of the insulation sheet was 640°C, the temperature of the inner surface was between 230°C and 240°C, and the surface temperature of the steel shell of the skid pipe was 68°C to 70°C. During the operation period, the moisture contained in the castable moved to the steel shell side and wetted the microporous insulation sheet, which meant that the microporous insulation sheet was unable to maximize its inherent insulation effect. As a result, the reduction rate of the heat extraction from the water-cooled pipe was only 23% to 28% compared to the conventional insulation lining (No. 1), and the continuous operation period was about 0.5 years, which was half the continuous operation period compared to the conventional insulation lining (No. 1).

[0045] [Table 2]

[0046] In Comparative Examples 9 and 10 in Table 2, a heat insulating sheet was provided inside the inner layer, that is, in the area in contact with the water-cooled pipe. Specifically, in Comparative Examples 9 and 10, an Al2O3-SiO2 heat insulating board and fiber blanket with a thickness of 80 mm were provided as the outer layer (first layer), and a fiber blanket with a thickness of 15 mm was provided as the inner layer (second layer). A microporous heat insulating sheet with a thickness of 5 mm was then placed radially inward from the inner layer (third layer).

[0047] In this case, the temperature of the outer surface of the heat insulation sheet was between 460℃ and 470℃, but the temperature of the inner surface was less than 50℃, and the heat insulation sheet condensed during the operation of the heating furnace, deteriorated, and peeled off. As a result, the continuous operation period was about 0.5 years, which was half the continuous operation period compared to the conventional heat insulation lining (No.1).

[0048] [Table 3]

[0049] In addition, in No. 11 in Table 3, the insulation lining has a two-layer structure consisting of an outer layer and an insulation sheet. Specifically, an Al2O3-SiO2 insulation board with a thickness of 95 mm was installed as the outer layer (first layer), and a microporous insulation sheet with a thickness of 5 mm was installed on the inside of the outer layer (second layer).

[0050] In this case, the temperature of the outer surface of the heat insulation sheet was between 570℃ and 580℃, but the temperature of the inner surface was less than 50℃, and the heat insulation sheet condensed during the operation of the heating furnace, deteriorated, and peeled off. As a result, the continuous operation period was about 0.5 years, which was half the continuous operation period compared to the conventional heat insulation lining (No.1).

[0051] [Table 4]

[0052] In addition, in No. 12 in Table 4, the thermal insulation lining has a two-layer structure consisting of an outer layer and an inner layer. Specifically, the outer layer (first layer) is an 85 mm thick Al2O3-SiO2 thermal insulation board, and the inner layer (second layer) is a 15 mm thick fiber blanket.

[0053] In this case, since no insulation sheet was installed, the reduction rate of heat extraction from the water-cooled pipes was only 33% to 36%, and the insulation effect was significantly reduced.

[0054] [Table 5]

[0055] Next, in No. 13 in Table 5, the radial thickness (layer thickness) of the outer layer was set to less than 50 mm. Specifically, an Al2O3-SiO2 insulation board with a layer thickness of 45 mm was used as the outer layer (first layer), and a fiber blanket with a layer thickness of 50 mm was provided as the inner layer (third layer). A microporous insulation sheet with a layer thickness of 5 mm was provided between the outer layer and the inner layer (second layer).

[0056] In this case, the reduction rate of heat extraction was 59% to 62%, and the continuous operation period was about one year because the amount of scale erosion increased due to the surface oxidation of the steel slab during operation.

[0057] [Table 6]

[0058] In No. 14 in Table 6, the radial thickness of the insulation sheet was set to more than 10 mm. Specifically, an Al2O3-SiO2 insulation board with a thickness of 70 mm was installed as the outer layer (first layer), and a fiber blanket with a thickness of 15 mm was installed as the inner layer (third layer). A microporous insulation sheet with a thickness of 15 mm was installed between the outer layer and the inner layer (second layer).

[0059] In this case, the insulation sheet did not conform well to the curved surface of the water-cooled pipe, making it difficult to wrap, and gaps formed between the outer and inner layers.As a result, the reduction in the amount of heat removed from the water-cooled pipe was 62% to 64% compared to the conventional insulation lining (No. 1). [Explanation of symbols]

[0060] P Water cooling pipe 1 inner layer 2. Heat insulation sheet 3 outer layer 4 additional layers 10. Insulating lining

Claims

1. A heat insulating lining that covers the outer periphery of a cooling member, a microporous heat insulating sheet provided on the outside of the cooling member; an inner layer made of a material having thermal insulation properties and disposed between the cooling member and the heat insulating sheet to suppress condensation on the heat insulating sheet; an outer layer made of a material having heat insulating properties, fire resistance, and not containing moisture and provided on the outer side of the heat insulating sheet; Optionally, an additional layer disposed between the outer layer and the insulating sheet; A thermal insulating lining.

2. The heat insulating sheet is microporous; the inner layer being a fiber blanket or fiber paper; and, 2. The insulating lining according to claim 1, wherein the outer layer is at least one of an insulation board, a fiber blanket, and a fiber paper.

3. The atmosphere outside the outer layer has a temperature of 800° C. or higher and 2000° C. or lower. The outer layer is provided so that the temperature of the outer surface of the heat insulating sheet is 750° C. or less, 2. The insulating lining of claim 1, wherein the inner layer is provided such that the temperature of the inner surface of the insulating sheet is greater than 80°C.

4. 2. The insulating lining according to claim 1, wherein the thickness of the outer layer is at least 50 mm.

5. The insulating lining according to claim 1 , wherein the insulating sheet has a thickness of 10 mm or less.

6. A method for applying a heat insulating lining to cover an outer periphery of a cooling member, comprising the steps of: an inner layer made of a material having thermal insulation properties is provided on the outside of the cooling member; a microporous insulating sheet disposed on the outside of the inner layer; an outer layer made of a material having heat insulating properties and fire resistance is provided on the outer side of the heat insulating sheet; Optionally, a further layer is provided between said outer layer and said insulating sheet.

7. A skid pipe, comprising a water-cooled pipe as the cooling member and a heat insulating lining according to any one of claims 1 to 5 formed in an annular structure around the water-cooled pipe.

8. A method for producing a heated slab, comprising using the skid pipe according to claim 7 in a heating furnace to heat a steel slab.

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