Method of testing thermal performance of an object

Abstract

The invention relates to the testing of the thermal performance of at least one object (6), such as a cable. First, at least one initial temperature curve is obtained by subjecting at least one first enclosure (1) having side walls lined with a thermal insulation material to a predetermined test profile inside a first furnace (3), while monitoring the temperature inside each of the at least one first enclosure. The at least one initial temperature curve is stored in a database (5). Then, at least one object is placed inside a second furnace (7) which is heated according to one of the at least one initial temperature curve, while determining a result test parameter for each of the at least one object, the test parameter being an indicator of the thermal performance. The method can for example be used in the process of selecting the necessary amount and type of thermal insulation material for a given application of the object.

Description

Technical Field

[0001] This invention relates to a method for testing the thermal properties of an object. In particular, the invention relates to a two-step method, wherein the first step includes obtaining at least one initial temperature profile, and the second step includes testing the thermal properties of the object by exposing it to a heating process based on the at least one initial temperature profile obtained in the first step. Background Technology

[0002] This invention relates to the field of fire-resistant technology for cables used in the oil and gas industry, such as large floating production facilities or storage and offloading vessels (FPSOs). For this purpose, cables are typically arranged in cable trays protected by surrounding fire-resistant boxes with sidewalls lined with thermally insulating material to protect the cables from the high temperatures generated during a potential fire. The actual cables selected for a specific project require very expensive fire-resistant testing in a fire laboratory to test their compliance with relevant specifications. Currently, no known cable can withstand a potential fire alone, thus requiring the application of passive fire protection, typically in the form of fire-resistant boxes arranged around the cable trays, containing the specified cables, or as fire-resistant sheaths or intumescent coatings applied to the cables. Following the application of fire protection, fire-resistant testing is performed, resulting in very high project-specific costs for verifying cable functionality due to the high cost of such high-temperature testing.

[0003] When building the next FPSO or any other installation, different cable assemblies are typically used. Therefore, due to the different cables, or the different associated fire scenarios or failure times, the project again incurs the same fire testing costs to verify the functionality of these cables. This results in very high project-specific fire testing costs for each project.

[0004] Similar considerations apply to other components that must withstand high temperatures, such as high-temperature resistant materials used in pipes, buildings, vehicles, or aircraft. Therefore, improved methods for testing the thermal properties of objects would be beneficial.

[0005] The purpose of this invention

[0006] The purpose of this invention is to provide a method for testing the thermal properties of an object that is more effective than known methods.

[0007] Another object of the present invention is to provide a method for testing the thermal properties of an object, which avoids the need to repeatedly perform expensive high-temperature tests.

[0008] The purpose of at least some embodiments of the present invention is to provide a method for simultaneously testing the thermal properties of multiple objects.

[0009] Another object of at least some embodiments of the present invention is to provide an efficient method for performing quality control on the thermal performance of a new product under consideration when replacing a known product.

[0010] Another object of the present invention is to provide an alternative to the prior art.

[0011] In particular, one object of the present invention is to provide a method for testing the thermal properties of an object to solve the above-mentioned problems of the prior art. Summary of the Invention

[0012] In a first aspect of the invention, the above-mentioned and several other objectives are intended to be achieved by providing a method for testing the thermal properties of at least one object, the method comprising the steps of:

[0013] - Provide at least one initial temperature profile, which has been obtained through the following means:

[0014] - Provide at least one first housing having sidewalls lined with thermally insulating material,

[0015] - Arrange temperature sensors, which are configured to monitor the temperature inside at least one of the first housings.

[0016] - Arrange at least one first shell inside the first furnace.

[0017] - The temperature of the first furnace is increased according to a predetermined test curve, while the temperature inside at least one first shell is monitored, thereby obtaining an initial temperature curve for each of the at least one first shell, and

[0018] - Store at least one initial temperature profile in the database for later use.

[0019] - If subsequent steps require more initial temperature profiles, the above steps may need to be repeated.

[0020] - Place at least one object inside the second furnace to test the thermal properties of at least one object.

[0021] - Heat a second furnace according to one of at least one initial temperature curves, and simultaneously determine a result test parameter for each of at least one object, which is an indicator of thermal performance.

[0022] As described above, this invention has been developed in the field of electrical cable technology. However, the method can be used for any kind of object that requires fire protection. It can be, for example, a steel pipe or part of a building.

[0023] The predetermined test profiles used to obtain at least one initial temperature profile are typically high-temperature test conditions determined by different fire scenario standards; see further details below. Since the temperature conditions to which the test object is exposed in the second furnace have already been obtained inside the thermally insulating shell, the temperature of the second furnace will typically be significantly lower than the temperatures used during the acquisition of at least one initial temperature profile.

[0024] As will be described in further detail below, the concept of the present invention is that at least one initial temperature profile stored can be reused, enabling testing of actual objects without having to repeat costly high-temperature tests.

[0025] A method for testing the thermal properties of at least one object can be considered a two-step process, wherein the first step includes using a first furnace and the second step includes using a second furnace. In some embodiments of the invention, both steps are performed by the same party, while in other embodiments, the first and second steps are performed by two different parties, with the first party providing at least one initial test curve to be used by the other party in the second step.

[0026] In some embodiments of the present invention, the method further includes the step of obtaining at least one initial temperature profile.

[0027] In such embodiments, the present invention may alternatively be described as a method for testing the thermal properties of at least one object, the method comprising the following steps:

[0028] - Obtain at least one initial temperature profile using the following methods:

[0029] - Provide at least one first housing having sidewalls lined with thermally insulating material,

[0030] - Arrange temperature sensors, which are configured to monitor the temperature inside at least one of the first housings.

[0031] - Arrange at least one first shell inside the first furnace.

[0032] - The temperature of the first furnace is increased according to a predetermined test curve, while the temperature inside at least one first shell is monitored, thereby obtaining an initial temperature curve for each of the at least one first shell, and

[0033] - Store at least one initial temperature profile in the database for later use.

[0034] - If subsequent steps require more initial temperature profiles, the above steps may need to be repeated.

[0035] - After obtaining at least one initial temperature profile, at least one object is placed inside a second furnace to test the thermal properties of at least one object.

[0036] - Heat a second furnace according to one of at least one initial temperature curve, while determining the result test parameters for each of at least one object, which are indicators of thermal performance.

[0037] By “arranging temperature sensors, which are configured to monitor the temperature inside each of at least one first housing,” it means that at least the parts of the temperature sensors necessary for the measurement are arranged as described. Some parts, such as, for example, extensions of shafts or wires, may extend to the outside of the first housing.

[0038] As described above, the present invention has been developed in the field of fire protection technology for cables used in the oil and gas industry, such as large floating production facilities or storage and unloading vessels. For this application, cables are typically arranged in cable trays protected by surrounding fireproof enclosures having sidewalls lined with thermally insulating material to protect the cables from the high temperatures generated during a potential fire. "Fireproof enclosure" refers to a protective cover arranged around parts such as cables to prevent exposure to high temperatures. While the following detailed description will focus on this application, the invention can also be used for testing other objects whose thermal properties require knowledge.

[0039] The method according to the invention can be considered a two-step process, namely, a first step of obtaining at least one initial temperature profile and a second step of using this at least one initial temperature profile for testing an object. The first step typically involves preparing multiple, such as a large number, initial temperature profiles and storing them in a database.

[0040] The predetermined test curve used in this first step typically corresponds to the high-temperature conditions that the tested object must be able to withstand during subsequent actual use of the same or similar objects. This would be, for example, a fire scenario, commonly referred to in the field of fire testing as, for example, an HC pool fire, a jet fire, or a high-heat-flux jet fire. Typically, multiple initial temperature curves are prepared using thermal insulation materials with different configurations, such as thermal insulation materials of different thicknesses and / or types. Different thicknesses can be obtained, for example, by using different numbers of layers of a given material. For each configuration, initial temperature curves can be obtained for different predetermined test curves, so that a large compilation of different combinations can be obtained and stored for later use. These test curves can be based on international or national standards required for a given application (such as applications within the oil and gas industry). Such high-temperature testing requires specialized equipment and is very expensive to perform. Therefore, an advantage of the present invention is that, once these initial temperature curves have been obtained, they can be used multiple times as needed in the second step of the method, including at locations other than where the initial temperature curves were obtained.

[0041] The second step of the method involves subjecting the object to be tested to an initial temperature profile measured at a location surrounded by thermal insulation material, i.e., at a temperature significantly lower than the temperature reached during the first furnace heating. Therefore, the measurements performed in the second furnace (i.e., the second step) can typically be completed at such low temperatures that conventional furnaces can be used. Consequently, these measurements of the object are significantly cheaper and can be repeated at a lower cost until a satisfactory combination of object and fire-resistant material for a given fire scenario has been found. More examples of the tests will be given below in conjunction with the accompanying drawings.

[0042] Another advantage of performing measurements in the first furnace without any object present is that this produces an initial temperature profile representing the worst-case scenario, since a portion of the heat will be spent heating the object during subsequent use under similar conditions. Therefore, if the object can withstand the temperature rise corresponding to the initial temperature profile, it can also withstand the actual and slightly lower or slower temperature rise after installation. Thus, this method has an inherent safety margin, making the design process based on the obtained results safe.

[0043] In some embodiments of the invention, multiple first shells lined with thermal insulation materials of different thicknesses and / or types are simultaneously arranged inside a first furnace. This allows for more efficient determination of the initial temperature profile.

[0044] The method may further include, prior to the step of increasing the temperature of the first furnace, arranging a second housing inside each of at least one first housing, the second housing having a corresponding temperature sensor disposed within the second housing, such that during the step of increasing the temperature of the first furnace according to a predetermined test curve, the temperature inside the second housing is monitored, thereby obtaining an initial temperature curve for each of the at least one first housing. "Corresponding temperature sensor" means the temperature sensor mentioned above disposed within the first housing. Such a second housing may, for example, be in the form of an empty cable tray, similar to those used for installing cables, for example, on a ship. Therefore, the test can simulate the actual use of the cable under test, as some heat will be dissipated by heating the cable tray. Using a cable tray also makes it easier to arrange the temperature sensor in a suitable manner, for example, without direct contact with thermal insulation material.

[0045] During the execution of the method described above, multiple objects can be simultaneously placed in a second furnace to test their respective thermal properties concurrently. Therefore, time- and cost-effective testing can be ensured.

[0046] The determination of the result test parameters for each of at least one object can be performed by monitoring the test parameters as a function of time. For example, this can be used as guidance to perform further testing when the actual test does not yield satisfactory results. It can also be used to confirm test results to obtain more information than simply whether a given test is a "failure" or a "pass."

[0047] In some embodiments of the invention, a database containing at least one initial temperature profile can be directly accessed by the control unit of the second furnace. This access can be wireless, for example, or it can be achieved by storing the database on a transferable medium such as a USB drive.

[0048] In some embodiments of the present invention, the object is a conductive material or comprises a conductive material, and the test parameter is its resistivity.

[0049] Typically, the choice of which parameter to use as the test parameter will depend, for example, on the type of object being tested and on what criteria are used as the basis for determining the necessary fire protection.

[0050] As mentioned above, at least one object can be at least one electrical cable. In this case, the test parameter will typically be resistivity, as its variation has been found to be a good measure of any potential negative effects of exposure to excessively high temperatures. An example of how resistivity can be monitored during the heating of the second furnace will be given with reference to the accompanying figures.

[0051] The first batch can be heated according to a predetermined test curve, which includes heating to temperatures of at least 800 degrees Celsius, such as at least 1000 degrees Celsius. Different examples of test curves will be shown in the figure.

[0052] In any of the embodiments described above, the method may further include a step of preparing for the certification of at least one test combination of the object and a first housing having sidewalls lined with thermally insulating material, the certification including verification to ensure predetermined thermal performance. Therefore, this method can be used not only to obtain the correct product for a given application, but also to obtain the necessary documentation.

[0053] In a second aspect, the present invention relates to the use of the methods described in any of the embodiments above in the process of selecting the necessary amount and type of thermal insulation material for a given application of an object. Or in other words, its use during the development process.

[0054] Alternatively, a second aspect of the invention relates to the use of the method described in any of the embodiments above for quality testing of an object to be used under predetermined conditions, which correspond to at least one first housing to be tested lined with thermal insulation material and at least one corresponding initial temperature profile. This would be a method for testing whether an object meets given requirements, for example when an alternative supplier of a product (such as a cable) offers a cheaper solution. In this case, the invention provides an efficient method for checking whether changing suppliers is safe.

[0055] The first and second aspects of the invention can be combined. These and other aspects of the invention will be apparent from and described with reference to the embodiments described below. Attached Figure Description

[0056] The method for testing the thermal properties of an object according to the invention will now be described in more detail with reference to the accompanying drawings. The drawings illustrate one mode of carrying out the invention and should not be construed as limiting for other possible embodiments falling within the scope of the appended claims.

[0057] Figure 1 The diagram schematically shows the first shell lined with thermal insulation material and arranged in the first furnace. Figure 1 .a and Figure 1 .b shows the first housing with and without additional cable trays.

[0058] Figure 2 An example of a first housing with different configurations of thermal insulation material is shown schematically.

[0059] Figure 3 An example of how three first shells can be arranged simultaneously in a first furnace is illustrated schematically.

[0060] Figure 4 Examples of different predetermined test curves to be used for heating the first furnace are shown.

[0061] Figure 5 This illustration demonstrates how to store multiple initial temperature profiles in a database for later use.

[0062] Figure 6 The steps for testing the thermal performance of multiple cables in a second furnace are illustrated schematically. Detailed Implementation

[0063] The following description of the invention is based on the technical application for which it was developed, namely, testing electrical cables and their necessary fire resistance using a surrounding fireproof enclosure lined with thermal insulation material. However, as stated above, the scope of protection also covers other applications.

[0064] As explained, the method for testing the thermal properties of at least one object (hereinafter referred to as an electrical cable) is a two-step process. In some embodiments of the invention, both steps are performed by the same party, while in other embodiments, the first and second steps are performed by two different parties, with the first party providing at least one initial test curve used by the other party in the second step. Figures 1 to 4 The first step of obtaining at least one initial temperature profile and storing it in a database for later use is described.

[0065] First, as schematically shown, prepare at least one first housing 1 having sidewalls lined with thermally insulating material, such as Figure 1 The first housing 1 in .a. For testing of electrical cables, the first housing 1 will typically be a fireproof box. The thermal insulation material can be any type of material considered for a given application. It will typically be selected as part of the design process for a given installation, such as by the supplier of materials and / or electrical cables. An example of a type of thermal insulation material that has been used during the development of this invention is listed under the trade name. The following is known. A temperature sensor 2, configured to monitor the temperature inside the first housing 1, is arranged within the first housing 1. The temperature signal obtained by the temperature sensor can be transmitted to a data acquisition unit (not shown), such as a computer, in any known manner (e.g., via wire or wirelessly). Figure 1 As shown in Figure 1a, the first shell 1 is arranged inside the first furnace 3. Figure 1 Figure .b shows an alternative test setup in which a second housing 4 is arranged inside a first housing 1 as an empty cable tray. The second housing 4 has a corresponding temperature sensor 2 disposed therein. In these figures, the first housing 1 and the second housing 4 are shown as box-shaped with closed ends. However, other shapes are also possible; see further examples. Figure 3 .

[0066] For most applications, a large number of initial temperature profiles are obtained and stored in a database for later use. Therefore, to make the process as efficient as possible, multiple first shells 1 lined with thermal insulation materials of different thicknesses and / or types are typically arranged simultaneously inside the first furnace 3. Figure 2 Examples of this different configuration are illustrated schematically in the form of two different types of materials, each of which was tested at different thicknesses. Figure 3 An example of three first shells 1 arranged inside the first furnace 3 is shown schematically. In this example, they are suspended from the ceiling of the furnace, but any suitable arrangement can be used.

[0067] The temperature of the first furnace 3 is then increased according to a predetermined test curve, while the temperature inside at least one first shell 1 is monitored. This typically involves heating to a temperature of at least 800 degrees Celsius, such as at least 1000 degrees Celsius. Figure 4 Examples of such test curves used to simulate different types of fire scenarios are shown. Each combination of the applied heating process and the configuration of the first shell lined with thermal insulation material results in an initial temperature curve. These initial temperature curves are stored in database 5 for later use, such as... Figure 5 This is illustrated schematically. If subsequent steps require more initial temperature profiles, the above steps are repeated. For example, this might be relevant if more fire scenarios need to be tested. Similarly, more initial temperature profiles can be added at later points in time, such as after the development of a new type of thermal insulation material or if fire scenarios that have not yet been tested become relevant.

[0068] Once the required number of initial temperature profiles have been obtained, they can be used in the second step of the method, where at least one object 6 (here, a cable) is arranged inside the second furnace 7 for testing the thermal properties of at least one object 6. This is in Figure 6 The diagram is schematically shown in cross-sectional view, in which multiple cables 6 are shown being tested simultaneously. In this embodiment, the cables are arranged in cable trays 8 that extend through the second furnace 7. Thermal insulation elements 9 are typically provided at the points where the cable trays 8 pass through the wall of the second furnace 7.

[0069] The second furnace 7 is heated according to one of the initial temperature curves, while simultaneously determining the resulting test parameters for each of the cables 6. The test parameters are indicators of the thermal performance of the cables 6. The temperature of the second furnace 7 is typically controlled by a control unit 10 with direct access to a database 5, where the initial temperature curves are stored. For electrical cables, the test parameter may be, for example, resistivity, which can be measured continuously or at specified intervals using any suitable type of instrument (such as a megohmmeter). How the test results are evaluated will depend on the specific application and is therefore not shown in the figures. Evaluation may, for example, include monitoring whether the test parameters used actually fall below predetermined thresholds during the testing process.

[0070] The method described above can be used, for example, in the process of selecting the necessary amount and type of thermal insulation material for a given application of an object. In that case, the method may include steps of preparing for the certification of the tested assembly of the object and a first housing having sidewalls lined with thermal insulation material, the certification including verification of predetermined thermal properties. For some applications, certifying one assembly is sufficient, while for others, certifying a series of assemblies would be advantageous.

[0071] The method described above can also be used to perform quality tests on objects to be used under predetermined conditions, corresponding to at least one first shell to be tested lined with thermal insulation material and at least one corresponding initial temperature profile. This would be relevant, for example, when obtaining a quote from an alternative supplier other than the previously used supplier. For some types of objects, it may be difficult to directly determine from the product whether a given performance is met, but this can be easily tested using the method according to the invention without having to repeat costly high-temperature measurements in the first furnace.

[0072] Although the invention has been described in conjunction with specific embodiments, it should not be construed as limiting it in any way to the presented embodiments. The scope of the invention is set forth in the appended set of claims. In the context of the claims, the terms "comprising" or "including" do not exclude other possible elements or steps. Furthermore, references such as "a" or "an" should not be construed as excluding multiple. The use of reference numerals in the claims relating to elements indicated in the drawings should also not be construed as limiting the scope of the invention. Moreover, individual features mentioned in different claims may be advantageously combined, and references to these features in different claims do not preclude the possibility and advantage of combining features.

Claims

1. A method for testing the thermal properties of at least one object (6), the method comprising the following steps: - Provide at least one initial temperature profile, which has been obtained by: - Provide at least one first housing (1) having sidewalls lined with thermally insulating material. - A temperature sensor (2) is arranged, which is configured to monitor the temperature inside each of the at least one first housing (1). - The at least one first shell (1) is arranged inside the first furnace (3), - Increase the temperature of the first furnace (3) according to a predetermined test curve, while monitoring the temperature inside the at least one first shell (1), thereby obtaining an initial temperature curve for each of the at least one first shell (1), and - Store at least one initial temperature profile in the database (5) for later use. - If more initial temperature profiles are needed for subsequent steps, the above steps may be repeated. - The at least one object (6) is placed inside the second furnace (7) for testing the thermal properties of the at least one object (6). - The second furnace (7) is heated according to one of at least one initial temperature curves, while determining the result test parameters for each of the at least one object (6), the test parameters being indicators of thermal performance.

2. The method according to claim 1, wherein, Multiple first shells (1) lined with thermal insulation materials of different thicknesses and / or types are simultaneously arranged inside the first furnace (3).

3. The method according to claim 1 or 2, further comprising, prior to the step of increasing the temperature of the first furnace (3), arranging a second housing (4) inside each of the at least one first housing (1), the second housing (4) having a corresponding temperature sensor (2) arranged inside the second housing (4), such that during the step of increasing the temperature of the first furnace (3) according to the predetermined test curve, the temperature inside the second housing (4) is monitored, thereby obtaining an initial temperature curve for each of the at least one first housing (1).

4. The method according to claim 1 or 2, wherein, Multiple objects (6) are placed in the second furnace (7) at the same time, so that their respective thermal properties are tested simultaneously.

5. The method according to claim 1 or 2, wherein, The determination of the result test parameters for each of the at least one object (6) is performed by monitoring the test parameters as a function of time.

6. The method according to claim 1 or 2, wherein, The database (5) storing the at least one initial temperature curve can be directly accessed by the control unit (10) of the second furnace (7).

7. The method according to claim 1 or 2, wherein, The object (6) is a conductive material or comprises a conductive material, and wherein the test parameter is its resistivity.

8. The method according to claim 1 or 2, wherein, The at least one object (6) is at least one electrical cable.

9. The method according to claim 1 or 2, wherein, The first furnace (3) is heated according to a predetermined test curve, which includes heating to a temperature of at least 800 degrees Celsius.

10. The method according to claim 1 or 2, wherein, The first furnace (3) is heated according to a predetermined test curve, which includes heating to a temperature of at least 1000 degrees Celsius.

11. The method according to claim 1 or 2, further comprising the step of certifying the combination of the object (6) and the first housing (1) having sidewalls lined with thermal insulation material, the certification including verification to ensure predetermined thermal performance.

12. Use of the method according to any one of the preceding claims in the process of selecting the necessary amount and the necessary type of thermal insulation material for a given application of the object (6).

13. The method according to any one of claims 1 to 11 is used for quality testing of an object (6) to be used under predetermined conditions, said predetermined conditions corresponding to at least one first housing (1) to be tested lined with thermal insulation material and at least one corresponding initial temperature profile.

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