JP5446658B2 - Storage tank anchor - Google Patents

Description

  The present invention relates to a storage tank anchor.

  Conventionally, an anchor used for a storage tank such as an LNG tank is known. This anchor is attached to the lower part of the side plate of the inner tank of the storage tank at the required interval in the circumferential direction of the inner tank, and prevents the corner of the inner tank from floating due to the internal pressure of the inner tank or the response at the time of earthquake (For example, refer to Patent Document 1).

  The anchor of the storage tank includes a strap plate-like strap plate, for example, in order to moor the inner tank to the outer tank. A stopper plate for locking the strap plate is attached to the upper portion of the strap plate. A stopper for preventing the upper part of the strap plate from coming out downward is welded to the side plate of the inner tank. The stopper includes, for example, a pair of bottom plates welded to the side plate of the inner tub, a pair of brackets erected on the bottom plate, and a cover plate placed horizontally between the pair of opposing brackets.

  A storage tank in which a secondary barrier is provided between the inner tank and the outer tank is also known. The secondary barrier is provided, for example, to prevent the liquid from leaking outside the storage tank when the liquid such as LNG leaks from the inner tank, and to ensure the liquid tightness of the storage tank.

JP 2003-269698 A

  In the conventional anchor, when the secondary barrier is not provided, the length of the strap plate can be sufficiently secured. Therefore, even if the inner tank is displaced in the circumferential direction due to the response during an earthquake and the circumferential force of the inner tank acts on the upper part of the strap plate, the length of the strap plate is generally at the lower end of the strap plate. Acts as a longitudinal axial force. Therefore, the shearing force generated in the strap plate width direction (in the circumferential direction of the inner tub) at the lower end of the strap plate is slight. However, even such a slight shear force may adversely affect the anchor or storage tank.

  Moreover, when a secondary barrier is provided between the inner tank and outer tank of a storage tank, there exists a subject that a big shearing stress generate | occur | produces in the welding part of a strap plate and a secondary barrier. When the secondary barrier is provided, the strap plate is provided so as to penetrate the secondary barrier. In order to ensure the liquid tightness of the secondary barrier, the strap plate is welded to the secondary barrier. At this time, the length of the strap plate from the stopper plate to the welded portion is significantly shorter than the length of the strap plate when the secondary barrier is not provided.

  Therefore, if the inner tank is displaced in the circumferential direction due to the response at the time of an earthquake and the circumferential force of the inner tank acts on the upper part of the strap plate, a large shear stress is applied to the welded portion between the strap plate and the secondary barrier. It occurs in the circumferential direction. If this shear stress exceeds the allowable value, the secondary barrier may be damaged, and liquid tightness and soundness may not be ensured.

  In order to avoid such a problem, it is conceivable that the length of the strap plate from the side plate of the inner tank to the secondary barrier is made sufficiently long. However, when the length of the strap plate is increased, the attachment position of the stopper on the side plate moves upward. Then, from the viewpoint of ensuring strength, it is necessary to increase the thickness of the side plate from the bottom plate to the stopper mounting position, which leads to a significant increase in cost.

  Therefore, the present invention provides an anchor that can reduce the shear stress in the circumferential direction of the inner tank acting on the outer tank or the secondary barrier of the storage tank at a low cost.

  In order to solve the above problems, an anchor of a storage tank according to the present invention is an anchor of a storage tank in which the inner tank of a storage tank having an inner tank and an outer tank is moored to the outer tank by an anchor body. In addition, the side plate of the inner tub is provided with a locking portion that is disposed so as to face the anchor main body and locks the upper portion of the anchor main body, and the anchor main body has a locking protrusion on the upper portion. The locking projection is disposed such that the lower end surface thereof faces the upper end surface of the locking portion, the upper end surface of the locking portion, the lower end surface of the locking projection, A surface treatment for reducing a coefficient of friction is performed on at least one of a surface of the locking portion facing the anchor body and a region of the anchor body facing the locking portion.

By configuring in this way, when the corner of the inner tank is lifted due to the internal pressure of the inner tank or the response at the time of the earthquake, the lower end surface of the locking projection fixed to the upper part of the anchor body, and the inner tank The upper end surface of the locking portion provided on the side plate of the side plate comes into contact. Thereby, an inner tank receives the tensile force resisting the force which the corner | angular part of an inner tank floats up from an anchor main body through a latching | locking part.
When a tensile force acts on the anchor body, the lower end surface of the locking projection comes into contact with the upper end surface of the locking portion provided on the side plate of the inner tank and receives a reaction force according to the tensile force. In this state, when the inner tub is displaced in the circumferential direction relative to the outer tub, the locking projection and the anchor main body receive a frictional force in the circumferential direction of the inner tub from the locking portion.
However, according to the present invention, at least one of the upper end surface of the locking portion, the lower end surface of the locking projection, the surface of the locking portion that faces the anchor body, and the region where the locking portion of the anchor body faces. Since the surface treatment for reducing the friction coefficient is performed, the frictional force in the circumferential direction of the inner tub received by the locking projection from the locking portion is reduced. Therefore, the circumferential force of the inner tub acting on the upper part of the anchor main body can be reduced, and the circumferential shear stress of the inner tub acting on the outer tub from the anchor main body can be reduced.

  The anchor of the storage tank according to the present invention is characterized in that the lower end surface of the locking projection is formed in a curved surface having a vertex that contacts the upper end surface of the locking portion.

With this configuration, when a tensile force acts on the anchor body, the vicinity of the apex of the lower end surface of the locking projection comes into contact with the upper end surface of the locking portion. In this state, when the inner tub is relatively displaced in the circumferential direction with respect to the outer tub, the locking projection receives the frictional force in the circumferential direction of the inner tub from the locking portion.
At this time, since the lower end surface of the locking projection is formed in a curved surface, it is possible to prevent the locking projection from being caught in the locking portion. For this reason, the locking projection easily slides on the upper end surface of the locking portion, and the anchor body and the inner tank are relatively easily displaced.
Therefore, the force acting on the upper part of the anchor body can be reduced, and the shear stress in the circumferential direction of the inner tank acting on the outer tank from the anchor body can be reduced.

  In the storage tank anchor according to the present invention, the lower end surface is a part of a spherical surface or an elliptical spherical surface.

By comprising in this way, the lower end surface of a latching convex part contact | abuts in the state of a substantially point contact with the upper end surface of a latching | locking part. Therefore, it is possible to more effectively prevent the locking convex portion from getting into the locking portion and being caught. For this reason, the locking projections are more likely to slide on the locking portions, and the anchor body and the inner tank are relatively more easily displaced.
Accordingly, the force acting on the upper portion of the anchor body can be reduced, and the shear stress in the circumferential direction of the inner tub acting on the outer tub by the anchor body can be reduced.

  The storage tank anchor according to the present invention is characterized in that the storage tank includes a secondary barrier between the inner tank and the outer tank, and the anchor body is fixed to the secondary barrier.

By configuring in this way, when the corner of the inner tank is lifted due to the internal pressure of the inner tank or the response at the time of the earthquake, the lower end surface of the locking projection fixed to the upper part of the anchor body, and the inner tank The upper end surface of the locking portion provided on the side plate of the side plate comes into contact. Thereby, an inner tank receives the tensile force resisting the force which the corner | angular part of an inner tank floats up from an anchor main body through a latching | locking part.
When a tensile force acts on the anchor body, the lower end surface of the locking projection comes into contact with the upper end surface of the locking portion provided on the side plate of the inner tank and receives a reaction force according to the tensile force. In this state, when the inner tub is displaced in the circumferential direction relative to the secondary barrier, the locking projection receives the frictional force in the circumferential direction of the inner tub from the locking portion.
However, according to the present invention, at least one of the upper end surface of the locking portion and the lower end surface of the locking projection is subjected to a surface treatment that reduces the friction coefficient. The frictional force in the circumferential direction of the inner tank to be received is reduced. Therefore, the circumferential force of the inner tank acting on the upper part of the anchor body can be reduced, and the circumferential shear stress of the inner tank acting on the secondary barrier from the anchor body can be reduced.

  The anchor of the storage tank according to the present invention is characterized in that the anchor body is formed in a band plate shape.

  By comprising in this way, the tensile strength of an anchor main body can be increased. Moreover, since a joining area with an outer tank or a secondary barrier increases, the shear stress of the circumferential direction of the inner tank which acts on an outer tank or a secondary barrier from an anchor main body can be reduced.

  The storage tank anchor according to the present invention is characterized in that the anchor body is formed in a rod shape.

  By comprising in this way, the force which acted on the upper part of an anchor main body acts mainly as an axial force of a tension | pulling direction. Therefore, the shear stress in the circumferential direction of the inner tank acting on the outer tank or the secondary barrier from the anchor body can be reduced.

  In the storage tank anchor according to the present invention, the anchor body slides between the secondary barrier and the locking portion to allow relative displacement in the circumferential direction between the inner tank and the secondary barrier. It comprises a part.

With this configuration, when the inner tank and the secondary barrier are relatively displaced in the circumferential direction, the sliding portion allows the displacement. Therefore, the circumferential force acting on the upper portion of the anchor body can be reduced.
Therefore, the shear stress in the circumferential direction of the inner tank acting on the secondary barrier from the anchor body can be reduced.

  The anchor of the storage tank of the present invention is characterized in that the surface treatment is formation of a solid lubricant film.

By comprising in this way, a solid lubricant film is formed in at least one of the upper end surface of a latching | locking part, and the lower end surface of a latching convex part, and a friction coefficient can be reduced. Thereby, the frictional force in the circumferential direction of the inner tub received by the locking projection from the locking portion is reduced, and the circumferential force acting on the upper portion of the anchor body can be reduced.
Therefore, the shear stress in the circumferential direction of the inner tank acting on the secondary barrier from the anchor body can be reduced.

  According to the present invention, when the inner tank and the outer tank or the secondary barrier are relatively displaced in the circumferential direction, the force acting on the upper part of the anchor body is reduced, and the inner tank acting on the outer tank or the secondary barrier is reduced. Circumferential shear stress can be reduced at low cost. Therefore, breakage of the outer tub or the secondary barrier can be prevented, and liquid tightness and soundness can be ensured.

It is sectional drawing which shows schematic structure of the storage tank which concerns on 1st embodiment of this invention. It is an enlarged front view of the anchor and stopper which concern on 1st embodiment of this invention. It is sectional drawing of the anchor and stopper which follow the AA line of FIG. It is an enlarged front view of the anchor and stopper which concern on 2nd embodiment of this invention. It is sectional drawing equivalent to FIG. 3 of the anchor and stopper which concern on 4th embodiment of this invention. It is sectional drawing equivalent to FIG. 3 of the anchor and stopper which concern on 4th embodiment of this invention.

<First embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the following drawings, the scale is appropriately changed for each member so that each member has a size that can be recognized on the drawing.

FIG. 1 is a cross-sectional view showing a schematic configuration of a storage tank 1 of the present embodiment.
As shown in FIG. 1, the storage tank 1 includes an inner tank 2 that stores a low-temperature liquid such as liquefied natural gas (LNG), and an outer tank 3 that surrounds the inner tank 2 and functions as a liquid barrier. I have. Further, when the liquid stored in the inner tank 2 leaks between the inner tank 2 and the outer tank 3 due to a response such as an earthquake, the secondary barrier 4 that accommodates the liquid and prevents it from leaking outside. Is provided.

  The inner tank 2 is formed of a low-temperature steel material such as 9% nickel steel or stainless steel. A cold insulation block 5 is installed below the bottom plate 2 b of the inner tank 2, and a cold insulation material 6 such as foam glass is filled outside the side plate 2 s of the inner tank 2. A secondary barrier 4 that surrounds the inner tank 2 via a cold insulating block 5 and a cold insulating material 6 is disposed outside the inner tank 2.

  The secondary barrier 4 is formed of, for example, a low-temperature steel material similar to that of the inner tank 2, and is provided in a liquid-tight manner to prevent liquid from leaking to the outside. Below the bottom plate 4 b of the secondary barrier 4, a cold insulation block 7 is disposed to form a cold insulation bottom portion. An outer tub 3 that surrounds the secondary barrier 4 is provided outside the secondary barrier 4.

  The outer tub 3 is formed of, for example, prestressed concrete (PC). An anchor box 8 is embedded in the bottom plate 3 b of the outer tub 3. Fixed to the anchor box 8 is a lower end portion 11e of a strap plate (anchor body) 11 of an anchor 10 that anchors the inner tank 2 to the outer tank 3.

  A stopper 20 for locking the upper portion 11t of the strap plate 11 is provided below the side plate 2s of the inner tank 2. A plurality of anchors 10 and stoppers 20 are installed at predetermined intervals in the circumferential direction of the inner tank 2. When the diameter of the inner tank 2 is about 80 m, for example, about 120 to 180 sets of anchors 10 and stoppers 20 are installed around the inner tank 2.

  The strap plate 11 is formed of, for example, a low-temperature steel material similar to the inner tub 2, and the upper portion 11 t is locked by the stopper 20. Moreover, between the inner tank 2 and the secondary barrier 4, it installs in the state inclined so that it might separate from the inner tank 2 in the downward side. The strap plate 11 passes through the secondary barrier 4, and a lower end portion 11 e is fixed to the anchor box 8 embedded in the bottom plate 3 b of the outer tub 3. Further, the strap plate 11 is welded and fixed to the secondary barrier 4 in order to maintain the liquid tightness of the secondary barrier 4 at the portion where the strap plate 11 penetrates the secondary barrier 4.

FIG. 2 is an enlarged front view of the anchor 10 and the stopper 20. FIG. 3 is a cross-sectional view of the anchor 10 and the stopper 20 taken along the line AA of FIG.
As shown in FIG. 2, the stopper 20 spans between a pair of seat plates 21 fixed to the side plate 2 s of the inner tank 2, a pair of brackets 22 erected on the seat plate 21, and the pair of brackets 22. The cover plate (locking part) 23 is provided. The seat plate 21, the bracket 22, and the cover plate 23 are each formed of a low-temperature steel material such as 9% nickel steel. The seat plate 21 is welded to the side wall 2 s of the inner tank 2, the bracket 22 is welded to the seat plate 21, and the cover plate 23 is welded to the bracket 22.

  As shown in FIGS. 2 and 3, the strap plate 11 is formed in a band plate shape extending downward, and is inserted between the cover plate 23 and the side plate 2s, and is disposed closer to the inner tub 2 than the cover plate 23 is. Has been. A stopper plate (locking convex portion) 12 for locking the upper portion 11 t of the strap plate 11 to the stopper 20 is fixed to the upper portion 11 t of the strap plate 11.

  The stopper plate 12 is formed of, for example, a low-temperature steel material similar to the strap plate 11 and is welded to the strap plate 11. The stopper plate 12 is disposed such that its lower end surface 12b faces the upper end surface 23t of the cover plate 23 of the stopper 20. Further, the lower end surface 12b of the stopper plate 12 and the upper end surface 23t of the cover plate 23 are formed to be substantially parallel.

At least one of the upper end surface 23t of the cover plate 23 and the lower end surface 12b of the stopper plate 12 is previously subjected to a surface treatment for reducing the friction coefficient. In the present embodiment, as this surface treatment, a solid lubricant film made of molybdenum disulfide is formed on both the upper end surface 23 t of the cover plate 23 and the lower end surface 12 b of the stopper plate 12. Therefore, the friction coefficient between the upper end surface 23t of the cover plate 23 and the lower end surface 12b of the stopper plate 12 is about 0.1, for example.
The solid lubricant film is formed by applying a solid lubricant in the form of a paint, followed by drying and heat-curing, after undergoing preliminary steps such as degreasing cleaning, surface treatment, preheating, and the like.

As shown in FIG. 3, the strap plate 11 is installed so as to spread outward in the radial direction of the inner tub 2 toward the lower side, and is arranged at an inclination angle θ <b> 1 that is separated from the inner tub 2 toward the lower side. The inclination angle θ1 is, for example, about 10 ° with respect to the side wall 2s of the inner tank 2.
Further, the cover plate 23 laid horizontally between the pair of brackets 22 is provided to be inclined with respect to the side plate 2s. The cover plate 23 is inclined such that the inclination angle θ2 of the facing surface 23i facing the strap plate 11 is equal to or larger than the inclination angle θ1 of the strap plate 11. In the present embodiment, the inclination angle θ2 of the facing surface 23i of the cover plate 23 is substantially equal to the inclination angle θ1 of the strap plate 11, and the facing surface 23i of the cover plate 23 and the strap plate 11 are substantially parallel.

Next, the operation of this embodiment will be described.
For example, when the corner portion 2c of the inner tank 2 shown in FIG. Ten tensile forces F act on the ten strap plates 11. At this time, as shown in FIGS. 2 and 3, the stopper plate 12 is fixed to the upper portion 11 t of the strap plate 11, and the lower end surface 12 b is disposed so as to face the upper end surface 23 t of the cover plate 23 of the stopper 20. ing.

  Therefore, when the tensile force F acts on the strap plate 11, the lower end surface 12b of the stopper plate 12 comes into contact with the upper end surface 23t of the cover plate 23 of the stopper 20, as shown in FIG. The lower end surface 12 b of the stopper plate 12 receives a reaction force corresponding to the tensile force F from the upper end surface 23 t of the cover plate 23. Thereby, the upper part 11t of the strap plate 11 is locked by the stopper 20 and is prevented from falling off from the stopper 20 provided on the side plate 2s of the inner tank 2. Therefore, the corner portion 2 c of the inner tank 2 can be prevented from being lifted by the tensile force F of the strap plate 11.

  For example, in response to an earthquake, the corner portion 2 c of the inner tank 2 tends to float and the inner tank 2 may be displaced relative to the secondary barrier 4 in the circumferential direction. At this time, the lower end surface 12b of the stopper plate 12 and the upper end surface 23t of the cover plate 23 are brought into contact with the lower end surface 12b of the stopper plate 12 in a state where a drag force corresponding to the tensile force F is applied from the upper end surface 23t of the cover plate 23. It slides relatively in the circumferential direction of the inner tank 2. The strap plate 11 is relatively displaced in the circumferential direction of the inner tank 2 between the pair of brackets 22 and 22 of the stopper 20 shown in FIG. Thereby, relative displacement in the circumferential direction of the inner tank 2, the secondary barrier 4, and the outer tank 3 can be allowed while preventing the corner portion 2 c of the inner tank 2 from being lifted.

Here, in the present embodiment, as shown in FIG. 3, the inclination angle θ2 of the facing surface 23i of the cover plate 23 is substantially equal to the inclination angle θ1 of the strap plate 11, and the opposing surface 23i of the cover plate 23 and the strap plate 11 Are almost parallel.
Therefore, when the tensile force F acts on the strap plate 11, the facing surface 23 i of the cover plate 23 and the facing surface 11 i of the strap plate 11 facing the cover plate 23 become parallel. Thereby, it is possible to prevent the facing surface 11 i of the strap plate 11 from being pressed against the facing surface 23 i of the cover plate 23. Therefore, the surface pressure does not act between the facing surface 11 i of the strap plate 11 and the facing surface 23 i of the cover plate 23.

  Therefore, even if the inner tub 2 is displaced relative to the secondary barrier 4 in the circumferential direction in a state where the tensile force F is applied to the strap plate 11, the opposing surface 11 i of the upper portion 11 t of the strap plate 11 and the cover plate 23. It is possible to prevent a frictional force from acting between the opposite surface 23i. Thereby, the shear stress which acts on the welding part WP with the secondary barrier 4 shown in FIG. 1 from the strap plate 11 can be reduced. Moreover, since the lower end surface 12b of the stopper plate 12 and the upper end surface 23t of the cover plate 23 are formed substantially in parallel, appropriate slip can be generated by the solid lubricant film.

  In the present embodiment, surface treatment is performed on both the upper end surface 23 t of the cover plate 23 of the stopper 20 provided on the side plate 2 s of the inner tank 2 and the lower end surface 12 b of the stopper plate 12 fixed to the strap plate 11. It is applied to form a solid lubricant film. Therefore, the friction coefficient between the upper end surface 23t of the cover plate 23 and the lower end surface 12b of the stopper plate 12 can be reduced to, for example, about one third when the solid lubricant film is not formed.

Therefore, when the inner tub 2 is displaced in the circumferential direction relative to the secondary barrier 4 with the tensile force F acting on the strap plate 11, the lower end surface 12 b of the stopper plate 12 becomes the upper end surface of the cover plate 23. The frictional force in the circumferential direction of the inner tank 2 received from 23t can be reduced to, for example, about one third.
Therefore, the circumferential force of the inner tub 2 acting on the upper portion 11t of the strap plate 11 can be reduced, and the shear stress acting on the welded portion WP of the secondary barrier 4 from the strap plate 11 can be reduced.

  In addition, as shown in FIG. 2, the strap plate 11 is formed in the shape of a strip having a wide width W, so that the strap plate 11 can be compared with the case of using a rod-like or linear strap (anchor body). Tensile strength can be increased. Moreover, since the joining area in the welding part WP with the secondary barrier 4 increases, the shear stress which acts on the welding part WP of the secondary barrier 4 from the strap plate 11 can be reduced.

As described above, according to the anchor 10 of the present embodiment, when the inner tub 2 and the secondary barrier 4 are relatively displaced in the circumferential direction, the circumference of the inner tub 2 that acts on the upper portion 11t of the strap plate 11 is obtained. Directional force is reduced. Thereby, the shear stress which acts on the welding part WP with the secondary barrier 4 can be reduced.
Therefore, it is possible to prevent the secondary barrier 4 from being damaged due to the internal pressure of the inner tank 2 or the response at the time of an earthquake, and to secure the liquid tightness and soundness of the secondary barrier 4.

Further, it is not necessary to make the length of the strap plate 11 longer than necessary in order to reduce the shear stress acting on the welded portion WP.
Therefore, an increase in cost due to an increase in the thickness of the side plate 2s of the inner tank 2 can be prevented, and a reduction in shear stress can be realized at a low cost.

<Second embodiment>
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the anchor 10 described in the first embodiment is used in that the rod-shaped strap bar 13 is used as the anchor body, and the stopper plate 14 having the lower end surface 14b formed in a curved surface is used as the locking projection. Is different. Since the other points are the same as in the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

FIG. 4 is an enlarged front view of the anchor 10 and the stopper 20 of the present embodiment.
As shown in FIG. 4, the anchor 10 </ b> B of the present embodiment includes a rod-shaped strap bar (anchor main body) 13 and a stopper plate (locking protrusion) 14 having a lower end surface 14 b formed in a curved shape. . The strap bar 13 and the stopper plate 14 are formed of a low-temperature steel material similar to the strap plate 11 and the stopper plate 12 of the first embodiment.
The stopper plate 14 is welded and fixed to the upper portion 13t of the strap bar 13.

  The lower end surface 14 b of the stopper plate 14 is formed in a downwardly convex curved shape, and has a vertex P that contacts the upper end surface 23 t of the cover plate 23 when a tensile force F acts on the strap bar 13. In the present embodiment, the lower end surface 14b of the stopper plate 14 is a part of a spherical surface.

Next, the operation of the present embodiment will be described.
As in the first embodiment, for example, when the corner 2c of the inner tank 2 shown in FIG. A tensile force F acts on the strap bar 13 of the anchor 10B of FIG.

  When the tensile force F acts on the strap bar 13, the vicinity of the apex P of the lower end surface 14 b of the stopper plate 14 comes into contact with the upper end surface 23 t of the cover plate 23. In this state, when the inner tub 2 is displaced in the circumferential direction relative to the secondary barrier 4, the lower end surface 14 b of the stopper plate 14 receives a frictional force in the circumferential direction of the inner tub 2 from the upper end surface 23 t of the cover plate 23. .

  At this time, in this embodiment, since the lower end surface 14b of the stopper plate 14 is formed in a curved surface shape, it is possible to prevent the lower end portion of the stopper plate 14 from getting into the cover plate 23 and being caught. Therefore, the stopper plate 14 is easily slid on the upper end surface 23t of the cover plate 23, and the strap bar 13 and the inner tank 2 are relatively easily displaced.

Further, in the present embodiment, since the curved surface of the lower end surface 14b of the stopper plate 14 is formed as a part of a spherical surface, the lower end surface 14b of the stopper plate 14 is in substantially point contact with the upper end surface 23t of the cover plate 23. Abut. Therefore, it is more effectively prevented that the stopper plate 14 gets into the cover plate 23 and gets caught. Therefore, the stopper plate 14 becomes easier to slide on the upper end surface 23t of the cover plate 23, and the strap bar 13 and the inner tank 2 are relatively easily displaced.
Therefore, the circumferential force of the inner tub 2 acting on the upper portion 13t of the strap bar 13 can be reduced, and the shear stress acting on the welded portion WP of the secondary barrier 4 from the strap bar 13 can be reduced.

  Furthermore, in this embodiment, since the rod-shaped strap bar 13 is used, the circumferential force of the inner tub 2 acting on the upper portion 13t of the strap bar 13 is mainly pulled in the welded portion WP with the secondary barrier 4. Acts as a direction axial force. Therefore, the shear stress acting on the secondary barrier 4 from the strap bar 13 can be reduced.

  As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained. In addition, the stopper plate 14 makes the cover plate 23 more slippery, and the force acting on the upper portion of the strap bar 13 is caused to act as an axial force in the tensile direction at the welded portion WP, so that the shear stress acting on the secondary barrier 4 is increased. Can be reduced.

<Third embodiment>
Next, a third embodiment of the present invention will be described with reference to FIGS. 5 and 6 with reference to FIGS. This embodiment is different from the anchor 10 described in the first embodiment in that sliding portions 40 and 50 are formed between the upper portion 11t of the strap plate 11 and the secondary barrier 4. Since the other points are the same as in the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

5 and 6 are cross-sectional views of the stopper and the strap plate corresponding to FIG. 3 of the first embodiment.
As shown in FIG. 5 and FIG. 6, the anchor 10 </ b> D of the present embodiment has a relative displacement in the circumferential direction between the inner tank 2 and the secondary barrier 4 between the upper portion 11 t of the strap plate 11 and the secondary barrier 4. Allowable sliding portions 40 and 50 are formed.

  As shown in FIG. 5, when the sliding part 40 is provided on the cover plate 23 side, the strap plate 11 is constituted by the upper plate 11A and the lower plate 11B. Then, the lower portion of the upper plate 11 </ b> A and the upper portion of the lower plate 11 </ b> B are slidably engaged in the circumferential direction of the inner tank 2 to form the sliding portion 40. At this time, at least one of the mutually opposing sliding surfaces 11a and 11b of the upper plate 11A and the lower plate 11B is subjected to the same surface treatment as in the first embodiment to reduce the friction coefficient of the sliding surfaces 11a and 11b. Is preferred.

As shown in FIG. 6, when providing the sliding part 50 in the secondary barrier 4 side, the sliding part 50 is comprised by the rail part 11R and the sliding plate 11P, for example.
The rail portion 11R is formed on the secondary barrier 4 at the upper end portion of the strap plate 11 penetrating the secondary barrier 4 so as to extend in the width W direction of the strap plate 11 (the circumferential direction of the inner tank 2).
The sliding plate 11P is inserted into the rail portion 11R and coupled to the strap plate 11 extending downward from the stopper 20 in a state in which the sliding plate 11P can slide in the width W direction of the strap plate 11 (the circumferential direction of the inner tank 2). ing.
Further, the same surface treatment as that of the first embodiment is applied to at least one of the mutually opposing sliding surfaces 11r and 11p of the rail portion 11R and the sliding plate 11P to reduce the friction coefficient of the sliding surfaces 11r and 11p. Is preferred.

Thus, in this embodiment, the sliding parts 40 and 50 as shown in FIG.5 and FIG.6 are formed between the upper part 11t of the strap plate 11, and the secondary barrier 4. FIG. Therefore, when the inner tub 2 and the secondary barrier 4 are relatively displaced in the circumferential direction, the sliding surfaces 11a and 11b and the sliding surfaces 11r and 11p of the sliding portions 40 and 50 slide to allow the displacement. To do. Thereby, the force of the circumferential direction of the inner tank 2 which acts on the upper part 11t of the strap plate 11 can be reduced.
Therefore, the shear stress acting on the secondary barrier 4 from the strap plate 11 can be reduced.

  As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained. In addition, the sliding portions 40 and 50 allow relative displacement in the circumferential direction of the inner tub 2 and the secondary barrier 4 to further reduce the shear stress acting on the welded portion WP of the secondary barrier 4 from the strap plate 11. be able to.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the storage tank provided with the secondary barrier has been described, but it goes without saying that the anchor of the present invention can be applied to a storage tank not provided with the secondary barrier. By applying the anchor of the present invention to a storage tank not provided with a secondary barrier, for example, the circumferential shearing force of the inner tank acting on the anchor box of the outer tank can be reduced. Thereby, even if it is a case where an inner tank is displaced in the circumferential direction by the response at the time of an earthquake, etc., it can prevent that an anchor, an outer tank, etc. have a bad influence, such as a breakage and a deformation.
Moreover, as long as the latching convex part has a lower end surface facing the upper end surface of the latching part, it may be integrally formed with the anchor main body. That is, instead of welding the stopper plate to the strap plate described in the above embodiment, for example, the strap plate may be directly processed to form the locking projection.

  Moreover, you may form a latching | locking part integrally with the side wall of an inner tank. Further, the locking portion does not have to be plate-shaped as long as the inclination angle of the opposing surface is equal to or larger than the inclination angle of the anchor body. For example, a columnar material may be cut and formed so that the thickness becomes thinner toward the bottom. Thereby, the intensity | strength of a latching | locking part can be improved.

  Further, the opposing surface of the locking portion may have an inclination angle larger than the inclination angle of the anchor body. For example, you may arrange | position so that the opposing surface of the cover plate demonstrated by the above-mentioned embodiment may be spaced apart from a strap plate so that the downward side of a cover plate may be sufficient. As a result, the cover plate and the strap plate are less likely to contact each other, and the frictional force is less likely to act.

  In the above-described embodiment, a solid lubricant other than molybdenum disulfide may be used. For example, use graphite, graphite, polytetrafluoroethylene resin (PTFE: Teflon (registered trademark) resin), etc. that have a low surface hardness, a high melting point, hardly burn-in, and good chemical stability. Can do.

In the above-described embodiment, the solid lubricant film may be formed on either the lower end surface of the stopper plate or the upper end surface of the cover plate. Thereby, the usage-amount of a solid lubricant can be reduced, a manufacturing process can be simplified, and cost can be reduced.
In addition to the formation of the solid lubricant film, the surface treatment may be performed by application of a liquid lubricant such as lubricating oil or polishing treatment. Thereby, the manufacturing process of an anchor can be simplified and manufacturing cost can be reduced.

In the above-described embodiment, the surface of the solid lubricant film facing the strap plate (or strap bar) of the cover plate (the above-described facing surface 23i) and the cover plate of the strap plate (or strap bar) are opposed. It may be formed in a region. Thereby, when the inner tank is displaced in the circumferential direction relative to the secondary barrier, the frictional force in the circumferential direction of the inner tank that the strap plate receives from the cover plate can be reduced.
Therefore, the circumferential force of the inner tub acting on the strap plate can be further reduced, and the shear stress acting on the welded portion of the secondary barrier from the strap plate can be further reduced.
In the present invention, the solid lubricant film is applied to at least one of the lower end surface of the stopper plate, the upper end surface of the cover plate, the opposing surface of the cover plate, and the region of the strap plate (or strap bar) facing the opposing surface. Should just be provided. As a result, the shear stress acting on the welded portion of the secondary barrier from the strap plate can be further reduced.

In the above-described embodiment, the shape of the lower end surface of the stopper plate may be a part of an ellipse or a part of a cylindrical surface instead of a part of a spherical surface.
Further, the sliding portion is not limited to the configuration described in the above embodiment as long as it allows relative displacement in the circumferential direction between the inner tank and the cover plate.

1 storage tank, 2 inner tank, 2s side plate, 3 outer tank, 4 secondary barrier, 10, 10B, 10C, 10D anchor, 11 strap plate (anchor body), 11t upper part, 11A upper plate (anchor body), 11B lower plate (Anchor body), 12 stopper plate (locking projection), 12b lower end surface, 13 strap bar (anchor body), 13t upper part, 14 stopper plate (locking projection), 14b lower end surface, 23 cover plate (locking) Portion), 23i facing surface (surface facing the anchor body), 23t upper end surface, 40 sliding portion, 50 sliding portion, θ1 inclination angle, θ2 inclination angle, P apex

Claims (4)

The storage tank provided with an inner tank and an outer tank is an anchor of the storage tank that is anchored to the outer tank by an anchor body,
The side plate of the inner tub is provided with a locking portion that is arranged to face the anchor main body and locks the upper portion of the anchor main body,
The anchor body is provided with a locking projection on the top,
The locking projection is disposed such that the lower end surface thereof faces the upper end surface of the locking portion,
At least one of the upper end surface of the locking portion, the lower end surface of the locking projection, a surface of the locking portion that faces the anchor body, and a region where the locking portion of the anchor body faces. , Surface treatment to reduce the coefficient of friction has been applied ,
The storage tank includes a secondary barrier between the inner tank and the outer tank,
The anchor body is fixed to the secondary barrier and formed in a strip shape, and allows a relative displacement in the circumferential direction between the inner tank and the secondary barrier between the upper portion and the secondary barrier. A storage tank anchor comprising a moving part .   The anchor of the storage tank according to claim 1, wherein the lower end surface of the locking projection is formed in a curved shape having a vertex that contacts the upper end surface of the locking portion.   3. The storage tank anchor according to claim 2, wherein the lower end surface is a part of a spherical surface or an elliptical spherical surface. The storage tank anchor according to any one of claims 1 to 3 , wherein the surface treatment is formation of a solid lubricant film.

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