Method for diagnosing deterioration of fiber-reinforced plastic liquid storage tanks

Abstract

To easily and accurately diagnose the deterioration of liquid storage tanks. [Solution] The liquid storage tank made of fiber-reinforced plastic has a liquid storage tank body 10 and a manhole 20 that communicates with the inside of the liquid storage tank body 10. The manhole 20 has a cylindrical portion 21 that protrudes outward from the liquid storage tank body 10 and a lid 30 that is provided to open and close the opening at the end of the cylindrical portion 21. The lid 30 has a lid body 30A and a plate portion 40 that protrudes from the inner surface of the lid body 30A. The thickness of the plate portion 40 is greater than the thickness of the wall portion 11 of the liquid storage tank body 10.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a liquid storage tank made of fiber - reinforced plastic and a method for diagnosing the deterioration of a liquid storage tank made of fiber - reinforced plastic.

Background Art

[0006] According to this configuration, it becomes possible to diagnose the deterioration of the liquid storage tank body in the following manner. First, the plate portion is separated from the lid body. Next, a test piece is formed by cutting the plate portion so that the thickness is the same as the thickness of the wall portion of the liquid storage tank body, while leaving one side of the plate portion in the thickness direction. The test piece formed in this way can be considered to have approximately the same mechanical properties as the wall portion of the liquid storage tank body after deterioration. Furthermore, the mechanical properties of the wall portion of the liquid storage tank body after deterioration change according to the degree of deterioration of the wall portion. From these points, by measuring the mechanical properties of the test piece and determining the deterioration state of the liquid storage tank body based on these mechanical properties, it is possible to diagnose the deterioration of the liquid storage tank without cutting off a part of the liquid storage tank body.

[0007] Furthermore, with the above configuration, since the plate portion that serves as the test piece for deterioration diagnosis is provided on the manhole cover, it is not necessary to change the configuration of the liquid storage tank body, unlike when the plate portion that serves as the test piece is placed separately inside the liquid storage tank body.

[0008] Therefore, deterioration of the liquid storage tank can be diagnosed easily and accurately. [Aspect 2] The lid has a plurality of plate portions, A fiber-reinforced plastic liquid storage tank according to Embodiment 1.

[0009] With this configuration, since the lid has multiple plate sections, when repeatedly diagnosing the deterioration of the liquid storage tank at time intervals, such as every few years, it is possible to use the multiple plate sections sequentially as test pieces. Therefore, it is easy to repeatedly diagnosing the deterioration of the liquid storage tank at time intervals while reusing the lid.

[0010] [Aspect 3] A method for diagnosing the deterioration state of a fiber-reinforced plastic liquid storage tank according to Embodiment 1 or Embodiment 2, A separation step of separating the plate portion from the lid body, A test piece forming step involves cutting the plate portion so that the plate portion has the same thickness as the wall portion of the liquid storage tank body, while leaving one side of the plate portion in the thickness direction; A measurement step for measuring the mechanical properties of the test specimen, The system includes a determination step for determining the deterioration state of the liquid storage tank body based on the aforementioned mechanical property values. A method for diagnosing the deterioration of fiber-reinforced plastic liquid storage tanks.

[0011] According to this method, the same effects and advantages as those of the fiber-reinforced plastic liquid storage tank described in Embodiment 1 can be achieved. [Aspect 4] The lid has a plurality of plate portions, The deterioration diagnosis of the liquid storage tank body is performed repeatedly at time intervals, and a different plate section is used for each deterioration diagnosis. A method for diagnosing the deterioration of a fiber-reinforced plastic liquid storage tank as described in Embodiment 3.

[0012] According to this method, the same effects and advantages as those of the fiber-reinforced plastic liquid storage tank described in Embodiment 2 can be achieved. [Effects of the Invention]

[0013] According to the present invention, deterioration diagnosis of a liquid storage tank can be performed easily and accurately. [Brief explanation of the drawing]

[0014] [Figure 1] FIG. 1 is a cross-sectional view centered on the wall of the liquid storage tank body and the manhole in the fiber-reinforced plastic liquid storage tank of one embodiment. [Figure 2] FIG. 2 is a rear view of the lid of the manhole in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view of the wall of the liquid storage tank body in FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view of the plate portion. [Figure 5] FIG. 5 is a flowchart showing the procedure of a method for diagnosing deterioration of a fiber-reinforced plastic liquid storage tank of one embodiment. [Figure 6] FIG. 6 is a cross-sectional view of the lid and is a view for explaining the separation step. [Figure 7] FIG. 7 is a cross-sectional view of the plate portion in a state separated from the lid and is a view for explaining the test piece forming step. [Figure 8] FIG. 8 is a cross-sectional view of the test piece. [Figure 9] FIG. 9 is a cross-sectional view of the wall of the deteriorated liquid storage tank body.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, referring to FIGS. 1 to 9, an embodiment of a fiber-reinforced plastic (hereinafter, FRP) liquid storage tank and a method for diagnosing deterioration of the FRP liquid storage tank will be described. <Configuration of FRP Liquid Storage Tank> As shown in FIG. 1, the FRP liquid storage tank stores a chemical solution such as hydrochloric acid, and has a liquid storage tank body 10 and a manhole 20 communicating with the inside of the liquid storage tank body 10.

[0016] The liquid storage tank of this embodiment is, for example, a so-called round tank and has a cylindrical liquid storage tank body 10. Note that the liquid storage tank is not limited to a round tank, and may be a square tank having a square cylindrical liquid storage tank body 10.

[0017] The manhole 20 has a cylindrical portion 21 that protrudes outward from the liquid storage tank body 10, and a lid 30 provided to open and close the opening at the tip of the cylindrical portion 21. The cylindrical portion 21 is cylindrical in shape. An annular flange 22 is integrally formed at the tip of the cylindrical portion 21.

[0018] As shown in Figures 1 and 2, the flange 22 has a plurality of bolt holes 23 provided in the circumferential direction of the flange 22, spaced apart from each other. The lid 30 has a lid body 30A and a plate portion 40 that protrudes from the inner surface of the lid body 30A.

[0019] As shown in Figure 2, the lid body 30A is disc-shaped. Multiple bolt holes 31 are provided on the outer circumference of the lid body 30A, spaced apart from each other in the circumferential direction of the lid 30. As shown in Figure 1, the lid 30 is fastened and fixed to the flange 22 by inserting bolts 61 through the bolt holes 31 of the lid 30 and the bolt holes 23 of the flange 22, and by screwing nuts 62 onto the bolts 61.

[0020] As shown in Figures 1 and 2, the plate portion 40 is, for example, rectangular in shape. Preferably, multiple plate portions 40 are provided protruding from the inner surface of the lid 30. In this embodiment, three plate portions 40 are arranged in a row with spacing between them in the thickness direction of the plate portion 40.

[0021] The walls 11 of the liquid storage tank body 10, the cylindrical portion 21 of the manhole 20, and the lid 30 (including the plate portion 40) are all made of corrosion-resistant FRP. As shown in Figure 3, the FRP that constitutes the wall portion 11 of the liquid storage tank body 10 has a reinforcing layer 12 and a corrosion-resistant layer 13 that is fixed to the inner surface of the reinforcing layer 12 and constitutes the liquid-contacting surface.

[0022] The reinforcing layer 12 has a well-known configuration, for example, it is composed of a thermosetting resin and glass fibers. The corrosion-resistant layer 13 has a well-known configuration, for example, consisting of a thermosetting resin and glass fibers.

[0023] The thickness Tw of the wall portion 11 is, for example, 7 mm. In this case, the thickness Tw1 of the reinforcing layer 12 is, for example, 5 mm. Also, the thickness Tw2 of the corrosion-resistant layer 13 is, for example, 2 mm. As shown in FIG. 4, the FRP constituting the plate portion 40 has a reinforcing layer 43 and a corrosion-resistant layer 44 that is fixed to the entire surface of the reinforcing layer 43 and forms the liquid contact surface.

[0024] The reinforcing layer 43 is made of the same material as the reinforcing layer 12 that constitutes the wall portion 11. The corrosion-resistant layer 44 is made of the same material as the corrosion-resistant layer 13 that constitutes the wall portion 11. The thickness Tp of the plate portion 40 is greater than the thickness Tw of the wall portion 11 (Tp > Tw). It is preferable that the thickness Tp of the plate portion 40 is twice or more the thickness Tw of the wall portion 11 of the liquid storage tank body 10. In this embodiment, the thickness Tp of the plate portion 40 is twice the thickness Tw of the wall portion 11 of the liquid storage tank body 10.

[0025] The thickness Tp of the plate portion 40 is, for example, 14 mm. In this case, the thickness Tp1 of the reinforcing layer 43 is, for example, 10 mm. Also, the thickness Tp2 of the corrosion-resistant layer 44 is, for example, 2 mm.

[0026] <Method for diagnosing deterioration of FRP liquid storage tank> As shown in FIG. 5, the method for diagnosing deterioration of an FRP liquid storage tank includes a separation step, a test piece formation step, a measurement step, and a determination step.

[0027] As shown by the two-dot chain line in FIG. 6, in the separation step, after being removed from the cylindrical portion 21 of the manhole 20 and washed, the plate portion 40 is separated from the lid body 30A of the lid 30. Here, the plate portion 40 is separated from the lid body 30A by cutting the plate portion 40 at the base end portion 45 with a tool.

[0028] As shown in Figures 7 and 8, in the specimen formation process, the plate portion 40 is formed by cutting the side 42 of the plate portion 40 opposite to the side 41 in the thickness direction of the plate portion 40 so that the thickness is the same as the thickness Tw of the wall portion 11, while leaving one side 41 of the plate portion 40.

[0029] In the measurement process, the mechanical properties of the test specimen 50 are measured. Examples of mechanical properties of the test specimen 50 include the tensile strength and bending strength of the test specimen 50. In the determination process, the deterioration state of the liquid storage tank body 10 is determined based on its mechanical properties.

[0030] In this embodiment, the deterioration diagnosis of the liquid storage tank described above is performed repeatedly at time intervals, and a different plate section 40 is used for each deterioration diagnosis. Here, the above time interval is not particularly limited, but for example, intervals of 5 years, 10 years, 15 years, etc. can be adopted.

[0031] <Effects of this embodiment> (1) The cover 30 of the manhole 20 has a cover body 30A and a plate portion 40 that protrudes from the inner surface of the cover body 30A. The thickness of the plate portion 40 is greater than the thickness of the wall portion 11 of the liquid storage tank body 10.

[0032] With this configuration, the test piece 50 formed as described above can be considered to have approximately the same mechanical properties as the wall portion 11 of the deteriorated liquid storage tank body 10. Furthermore, the mechanical properties of the deteriorated wall portion 11 change according to the degree of deterioration of the wall portion 11. For example, the tensile strength and bending strength of the wall portion 11 decrease as the degree of deterioration of the wall portion 11 increases. Therefore, by measuring the mechanical properties of the test piece 50 and determining the deterioration state of the liquid storage tank body 10 based on these mechanical properties, it is possible to diagnose the deterioration of the liquid storage tank without cutting off a part of the liquid storage tank body 10.

[0033] Furthermore, since the plate portion 40, which will serve as the test piece 50 for deterioration diagnosis, is provided on the lid 30 of the manhole 20, unlike the case where the plate portion that will serve as the test piece is separately placed inside the liquid storage tank body 10, the configuration of the liquid storage tank body 10 does not need to be changed.

[0034] Therefore, deterioration of the liquid storage tank can be diagnosed easily and accurately. (2) Since the lid 30 has multiple plate sections 40, when repeatedly diagnosing the deterioration of the liquid storage tank at time intervals, such as every few years, it is possible to use the multiple plate sections 40 sequentially as test pieces 50. Therefore, it is easy to repeatedly diagnosing the deterioration of the liquid storage tank at time intervals while reusing the lid 30.

[0035] (3) The method for diagnosing deterioration of an FRP liquid storage tank comprises a separation step, a test piece formation step, a measurement step, and a determination step. This method can produce the same effects as (1).

[0036] (4) The method for diagnosing the deterioration of an FRP liquid storage tank involves repeatedly diagnosing the deterioration of the liquid storage tank at time intervals, and using a different plate section 40 for each deterioration diagnosis. This method can produce the same effects as (2).

[0037] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically. The cylindrical portion 21 of the manhole 20 is not limited to a cylindrical shape, but may also be a rectangular tube with a rectangular cross-section. In this case, the lid portion 30 may be a rectangular plate.

[0038] The number of plate portions 40 provided on the lid 30 is not limited to three; it may be two or fewer, or four or more. In the above embodiment, the three plate portions 40 are arranged in a row with spacing between them in the thickness direction of the plate portions 40, but the arrangement of the plate portions 40 can be changed as appropriate.

[0039] The thickness Tp of the plate portion 40 may be less than twice the thickness Tw of the wall portion 11 of the liquid storage tank body 10. Even in this case, if the degree of deterioration of the liquid storage tank is relatively small, a test piece 50 having approximately the same mechanical properties as the wall portion 11 of the liquid storage tank body 10 can be formed by cutting the side surface 42 of the plate portion 40. [Explanation of Symbols]

[0040] 10…Liquid storage tank body 11...Wall part 12…Reinforcement Layers 13…Corrosion-resistant layer 20... Manhole 21...Cylinder part 22…Flange 23… Bolt holes 30…Lid 30A... Lid body 31… Bolt holes 40...Plate section 41, 42… side view 43…Reinforcement 44...Corrosion-resistant layer 45...Proximal end 50... Test piece 61... Bolts 62... Nut

Claims

1. A liquid storage tank made of fiber-reinforced plastic, comprising a liquid storage tank body and a manhole communicating with the inside of the liquid storage tank body, The manhole has a cylindrical portion that protrudes outward from the liquid storage tank body, and a lid provided to open and close the opening at the tip of the cylindrical portion. The lid comprises a lid body and a plate portion that protrudes from the inner surface of the lid body. The thickness of the plate portion is greater than the thickness of the wall portion of the liquid storage tank body. A liquid storage tank made of fiber-reinforced plastic.

2. The lid has a plurality of plate portions, A fiber-reinforced plastic liquid storage tank according to claim 1.

3. A method for diagnosing deterioration of a fiber-reinforced plastic liquid storage tank according to claim 1 or claim 2, A separation step of separating the plate portion from the lid body, A test piece forming step involves cutting the plate portion so that the plate portion has the same thickness as the wall portion of the liquid storage tank body, while leaving one side of the plate portion in the thickness direction; A measurement step for measuring the mechanical properties of the test specimen, The system includes a determination step for determining the deterioration state of the liquid storage tank body based on the aforementioned mechanical property values. A method for diagnosing the deterioration of fiber-reinforced plastic liquid storage tanks.

4. The lid has a plurality of plate portions, The deterioration diagnosis of the liquid storage tank is performed repeatedly at time intervals, and a different plate section is used for each deterioration diagnosis. A method for diagnosing the deterioration of a fiber-reinforced plastic liquid storage tank according to claim 3.

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