Loop Test Equipment For Slow Strain Rate Test

Abstract

This document relates to a loop test device for a Slow Strain Rate Test (hereinafter 'SSRT'). The proposed loop test device comprises: a test chamber having an internal space for receiving ammonia; piping providing an inflow and outflow path for the ammonia in the test chamber; and a pump providing an output for the inflow and outflow of the ammonia through the piping, wherein the device is configured to adjust the ammonia flow rate in the test chamber or the piping by adjusting the output of the pump.

Description

Technology Field

[0001] The following description relates to a loop test apparatus for a Slow Strain Rate Test (hereinafter 'SSRT'), specifically to a test apparatus configured to perform SSRT in a test apparatus simulating an ammonia cargo tank environment. Background Technology

[0002] With the recent rise in demand for measures against global warming, ammonia, which does not emit carbon dioxide during combustion, is attracting attention as a next-generation energy source. Furthermore, as ammonia can function as a carrier for hydrogen, which is difficult to transport and store, demand for it is increasing. Accordingly, research and development on ammonia storage and transport technologies, particularly regarding the construction of large ammonia tanks made of high-strength steel, is being continuously conducted.

[0003] Meanwhile, ammonia is corrosive to steel, and stress corrosion cracking (SCC) can occur in steel exposed to liquid or gaseous ammonia. Therefore, it is essential to verify the SCC resistance characteristics of steel in which ammonia is stored.

[0004] Figure 1 is a diagram illustrating a device used in the evaluation method for determining the suitability of metal materials in an ammonia environment by the IMO.

[0005] The International Maritime Organization (IMO) specifies the Four-Point Bending Test (FPBT) as an evaluation method for determining the suitability of metal materials in an ammonia environment. Figure 110 of Fig. 1 shows a bender to provide bending force in ammonia, and Figure 110 of Fig. 1 shows a jig to fix the specimen.

[0006] Specifically, the FPBT stipulated by the IMO specifies the following conditions.

[0007] 1) Specimen type: Base material and weldment

[0008] 2) Applied stress: Applied at 100% of the material's yield strength

[0009] 3) Environment: Liquid / gaseous ammonia conditions

[0010] 4) Evaluation period: 30 days

[0011] 5) Check for the occurrence of SCC after the above test

[0012] type temperature Ammonia composition Liquid -33.5℃ 0.1 wt.% H2O + 2.5 ppm O2+ NH3bal. 2.5 ppm O2+ NH3bal. Gas Ambient Pure NH3(≥ 99.99 %) (7N) 0.9 % volume O2+ NH3bal.

[0013] However, the evaluation method under the IMO is not considered an evaluation method capable of determining material conformity because SCC does not occur even when IGC standards are exceeded.

[0014] Specifically, as a result of research conducted by the applicant in 2023, it was confirmed that no SCC occurred in steels of Act. YS 388 to 835 MPa under IMO test conditions. Although the test was evaluated based on IMO regulations, it was confirmed that no ammonia SCC occurred in any of the specimens, even though the yield strengths of E500 and PFS700 in [Table 2] below showed a significant difference from IGC regulations.

[0015] [ Table 2 ]

[0016]

[0017] Accordingly, there is a need for an evaluation method capable of simulating the actual cargo hold environment.

[0019] In addition, to prevent SCC in ammonia cargo tanks, restrictions are placed not only on the ammonia composition (oxygen, hydrogen) but also on the yield strength (YS) and Ni content of the cargo tank steel; however, the technical basis for these restriction regulations appears to be insufficient.

[0020] Due to the upper limit of steel yield strength and restrictions on Ni content, only a very limited range of steel can be applied when selecting cargo tank materials, which has the disadvantage of incurring additional purchasing costs and making it impossible to handle various fuels. The problem to be solved

[0021] In one aspect of the present invention for solving the problem described above, a loop test device configured to perform SSRT in a test device simulating an actual ammonia cargo tank environment is proposed.

[0022] In addition, according to the embodiments, we intend to describe in detail the configuration for applying dynamic stress simulating actual cargo tank conditions using such a loop test device, the conditions for applying dynamic stress, and the configuration for controlling the temperature conditions of ammonia.

[0023] The problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0024] In one aspect of the present invention for solving the problem described above, a loop test device for a Slow Strain Rate Test (SSRT) is proposed, comprising: a test chamber having an internal space for receiving ammonia; a pipe providing an inflow and outflow path for the ammonia in the test chamber; and a pump providing an output for the inflow and outflow of the ammonia through the pipe, wherein the output of the pump is adjusted to adjust the flow rate of the ammonia in the test chamber or the pipe.

[0025] At this time, it is preferable to additionally include a stress application module for applying dynamic stress to a specimen immersed in ammonia within the test chamber.

[0026] In addition, the pump can control the circulation of the ammonia through the piping to correspond to the environment of the ammonia cargo tank.

[0027] In addition, it is preferable that the piping be formed in a loop structure that allows the ammonia discharged from the test chamber to flow back into the test chamber.

[0028] In addition, a temperature measuring device for measuring the temperature of the ammonia within the test chamber may be additionally included, and the temperature of the ammonia may be configured to be maintained within a predetermined range using the temperature measuring device.

[0029] Preferably, the temperature of the ammonia can be controlled to have a range of -33°C or higher and 45°C or lower.

[0030] The above ammonia may include liquid ammonia and gaseous ammonia. Effects of the invention

[0031] According to the embodiments of the present invention as described above, the evaluation method under current IMO regulations can be supplemented or replaced by using a loop test device configured to perform SSRT in a test device simulating an actual ammonia cargo tank environment.

[0032] In addition, according to the embodiment, the configuration for applying dynamic stress simulating actual cargo tank conditions using this loop test device, the conditions for applying dynamic stress, and the configuration for controlling the temperature conditions of ammonia are also specified in detail, so that the SCC of metal materials due to ammonia can be tested more accurately.

[0033] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0034] Figure 1 is a diagram illustrating a device used in the evaluation method for determining the suitability of metal materials in an ammonia environment by the IMO. FIG. 2 is a diagram illustrating the configuration of a loop test device for SSRT according to one embodiment of the present invention. FIG. 3 is a drawing showing an example of a specimen immersed in ammonia in a test chamber according to one embodiment of the present invention. FIGS. 4 and FIGS. 5 are drawings for explaining the temperature setting conditions of ammonia according to one embodiment of the present invention. Specific details for implementing the invention

[0035] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0036] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0038] FIG. 2 is a diagram illustrating the configuration of a loop test device for SSRT according to one embodiment of the present invention.

[0039] As mentioned above, the IMO presents a method for evaluating metal materials in an ammonia environment; however, this can be viewed as a test verification method that does not consider actual cargo tank environments, and it has been confirmed that SCC does not occur even when there are significant differences from IGC regulations.

[0040] Therefore, in one embodiment of the present invention, when selecting a metal material, it is necessary to test and verify the metal material through the application of dynamic stress that considers the stress corrosion cracking mechanism, and to simulate a test environment in which ammonia flow occurs in an actual cargo tank, and thus a loop test device as shown in FIG. 1 is proposed.

[0041] A loop test device for this purpose may include: a test chamber (210) having an internal space for receiving ammonia; a pipe (220) providing an inflow and outflow path for ammonia to the test chamber (210); and a pump (230) providing an output for the inflow and outflow of ammonia through the pipe (220).

[0042] It is preferable that such a loop test device be configured to adjust the ammonia flow rate in the test chamber (210) or the piping (220) by adjusting the output of the pump (230). That is, the ammonia flow rate can be controlled by adjusting the output of the circulation pump (230), thereby allowing the ammonia to be circulated to correspond to the actual cargo tank environment. That is, in one embodiment of the present invention, it is preferable that the piping (220) be formed in a loop structure such that the ammonia discharged from the test chamber (210) can be re-introduced into the test chamber (210), as shown in FIG. 2.

[0043] In addition, according to the embodiment, as shown in FIG. 2, the inflow / outflow of ammonia from the chamber (210) can be controlled through one or more valves (240).

[0044] In addition, as shown in FIG. 2 according to the embodiment, various measuring instruments (250) may be provided, and, for example, a temperature measuring instrument (250) for measuring the temperature of ammonia within the test chamber (210) may be additionally included. It is preferable to configure the temperature of ammonia to be maintained within a predetermined range using such a temperature measuring instrument (250), and specific temperature control will be described later.

[0046] Meanwhile, a loop test device according to one embodiment of the present invention may additionally include a stress application module for applying dynamic stress to a specimen (260) immersed in ammonia within a test chamber (210).

[0047] FIG. 3 is a drawing showing an example of a specimen immersed in ammonia in a test chamber according to one embodiment of the present invention.

[0048] As shown in Fig. 3, since the test is performed by immersing the specimen in ammonia while it is sealed, the test can be performed using both liquid ammonia and gaseous ammonia.

[0049] In addition, by utilizing this structure and applying flow conditions within the cargo tank, the occurrence of SCC can be tested more accurately.

[0050] Flow conditions within the cargo tank are parameters involved in the adsorption and desorption of oxygen film and affect the occurrence of SCC. If the oxygen film is desorbed due to strong impacts such as sloshing, it can affect the occurrence of SCC; conversely, an appropriate flow environment can accelerate the adsorption of the oxygen film and affect the prevention of SCC.

[0051] However, since the internal flow environment of the cargo tank changes depending on design conditions, it is difficult to provide specific figures. Currently, the IMO ammonia SCC test evaluation regulations do not take into account the flow conditions inside the cargo tank.

[0052] Accordingly, in one embodiment of the present invention, the condition of reciprocating motion at least once every 3 seconds, as proposed in the IMO PSPC evaluation method, is presented as a flow condition. However, the flow condition according to the present invention is not limited thereto.

[0054] FIGS. 4 and FIGS. 5 are drawings for explaining the temperature setting conditions of ammonia according to one embodiment of the present invention.

[0055] Temperature is a parameter involved in corrosion rate and ammonia condensation, and it affects the occurrence of SCC.

[0056] During the operation of an ammonia carrier, the boiling point at atmospheric pressure (-33.5 o C) Although managed below this level, the specific temperature conditions of the ammonia carrier are as shown in Fig. 4, and especially during cargo loading and unloading, the maximum is 45 o The temperature can rise up to C. At this time, ammonia may re-condense in the cargo tank at a lower temperature, causing SCC. Figure 5 is a diagram showing whether SCC occurs due to the temperature difference between the specimen and gaseous ammonia.

[0058] Under the current IMO ammonia SCC test evaluation regulations, -33.5, -20 o The ammonia temperature is set to C, Ambient, and three other values; accordingly, in one embodiment of the present invention, the temperature condition of the ammonia evaluation method is set to -33.5 considering actual operating conditions. o C or higher 45 o It is suggested to set it to C or lower.

[0060] The detailed description of the preferred embodiments of the present invention disclosed above is provided to enable those skilled in the art to implement and practice the present invention. Although the present invention has been described with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the invention. For example, those skilled in the art may utilize each configuration described in the above embodiments in a manner that combines with one another.

[0061] Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but to be given the broadest scope consistent with the principles and novel features disclosed herein. Explanation of the symbols

[0062] 110: Vendor 120: Jig 210: Test chamber 220: Piping 230: Pump 240: Valve 250: Measuring instrument (temperature measuring instrument) 260: Psalm

Claims

Claim 1 A loop test device for a Slow Strain Rate Test (SSRT), comprising: a test chamber having an internal space for receiving ammonia; piping providing an inflow and outflow path for the ammonia in the test chamber; and a pump providing an output for the inflow and outflow of the ammonia through the piping, wherein the output of the pump is adjusted to adjust the flow rate of the ammonia in the test chamber or the piping. Claim 2 A loop test device for SSRT according to claim 1, further comprising a stress application module for applying dynamic stress to a specimen immersed in ammonia within the test chamber. Claim 3 A loop test device for SSRT according to claim 1, wherein the pump controls the circulation of the ammonia through the piping to correspond to the environment of the ammonia cargo tank. Claim 4 A loop test device for SSRT according to claim 1, wherein the piping is formed in a loop structure that allows the ammonia discharged from the test chamber to flow back into the test chamber. Claim 5 A loop test device for SSRT according to claim 1, further comprising a temperature measuring device for measuring the temperature of the ammonia within the test chamber, and configured to maintain the temperature of the ammonia within a predetermined range using the temperature measuring device. Claim 6 A loop test device for SSRT according to claim 5, wherein the temperature of the ammonia is controlled to have a range of -33°C or higher and 45°C or lower. Claim 7 A loop test device for SSRT according to claim 1, wherein the ammonia comprises liquid ammonia and gaseous ammonia.

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